geologic fractures: Topics by WorldWideScience.org

Sample records for geologic fractures

Simulation of Anisotropic Rock Damage for Geologic Fracturing

Science.gov (United States)

Busetti, S.; Xu, H.; Arson, C. F.

2014-12-01

A continuum damage model for differential stress-induced anisotropic crack formation and stiffness degradation is used to study geologic fracturing in rocks. The finite element-based model solves for deformation in the quasi-linear elastic domain and determines the six component damage tensor at each deformation increment. The model permits an isotropic or anisotropic intact or pre-damaged reference state, and the elasticity tensor evolves depending on the stress path. The damage variable, similar to Oda's fabric tensor, grows when the surface energy dissipated by three-dimensional opened cracks exceeds a threshold defined at the appropriate scale of the representative elementary volume (REV). At the laboratory or wellbore scale (1000m) scales the damaged REV reflects early natural fracturing (background or tectonic fracturing) or shear strain localization (fault process zone, fault-tip damage, etc.). The numerical model was recently benchmarked against triaxial stress-strain data from laboratory rock mechanics tests. However, the utility of the model to predict geologic fabric such as natural fracturing in hydrocarbon reservoirs was not fully explored. To test the ability of the model to predict geological fracturing, finite element simulations (Abaqus) of common geologic scenarios with known fracture patterns (borehole pressurization, folding, faulting) are simulated and the modeled damage tensor is compared against physical fracture observations. Simulated damage anisotropy is similar to that derived using fractured rock-mass upscaling techniques for pre-determined fracture patterns. This suggests that if model parameters are constrained with local data (e.g., lab, wellbore, or reservoir domain), forward modeling could be used to predict mechanical fabric at the relevant REV scale. This reference fabric also can be used as the starting material property to pre-condition subsequent deformation or fluid flow. Continuing efforts are to expand the present damage
Statistical geological discrete fracture network model. Forsmark modelling stage 2.2

Energy Technology Data Exchange (ETDEWEB)

Fox, Aaron; La Pointe, Paul [Golder Associates Inc (United States); Simeonov, Assen [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden); Hermanson, Jan; Oehman, Johan [Golder Associates AB, Stockholm (Sweden)

2007-11-15

The Swedish Nuclear Fuel and Waste Management Company (SKB) is performing site characterization at two different locations, Forsmark and Laxemar, in order to locate a site for a final geologic repository for spent nuclear fuel. The program is built upon the development of Site Descriptive Models (SDMs) at specific timed data freezes. Each SDM is formed from discipline-specific reports from across the scientific spectrum. This report describes the methods, analyses, and conclusions of the geological modeling team with respect to a geological and statistical model of fractures and minor deformation zones (henceforth referred to as the geological DFN), version 2.2, at the Forsmark site. The geological DFN builds upon the work of other geological modelers, including the deformation zone (DZ), rock domain (RD), and fracture domain (FD) models. The geological DFN is a statistical model for stochastically simulating rock fractures and minor deformation zones as a scale of less than 1,000 m (the lower cut-off of the DZ models). The geological DFN is valid within four specific fracture domains inside the local model region, and encompassing the candidate volume at Forsmark: FFM01, FFM02, FFM03, and FFM06. The models are build using data from detailed surface outcrop maps and the cored borehole record at Forsmark. The conceptual model for the Forsmark 2.2 geological revolves around the concept of orientation sets; for each fracture domain, other model parameters such as size and intensity are tied to the orientation sets. Two classes of orientation sets were described; Global sets, which are encountered everywhere in the model region, and Local sets, which represent highly localized stress environments. Orientation sets were described in terms of their general cardinal direction (NE, NW, etc). Two alternatives are presented for fracture size modeling: - the tectonic continuum approach (TCM, TCMF) described by coupled size-intensity scaling following power law distributions
Statistical geological discrete fracture network model. Forsmark modelling stage 2.2

International Nuclear Information System (INIS)

Fox, Aaron; La Pointe, Paul; Simeonov, Assen; Hermanson, Jan; Oehman, Johan

2007-11-01

The Swedish Nuclear Fuel and Waste Management Company (SKB) is performing site characterization at two different locations, Forsmark and Laxemar, in order to locate a site for a final geologic repository for spent nuclear fuel. The program is built upon the development of Site Descriptive Models (SDMs) at specific timed data freezes. Each SDM is formed from discipline-specific reports from across the scientific spectrum. This report describes the methods, analyses, and conclusions of the geological modeling team with respect to a geological and statistical model of fractures and minor deformation zones (henceforth referred to as the geological DFN), version 2.2, at the Forsmark site. The geological DFN builds upon the work of other geological modelers, including the deformation zone (DZ), rock domain (RD), and fracture domain (FD) models. The geological DFN is a statistical model for stochastically simulating rock fractures and minor deformation zones as a scale of less than 1,000 m (the lower cut-off of the DZ models). The geological DFN is valid within four specific fracture domains inside the local model region, and encompassing the candidate volume at Forsmark: FFM01, FFM02, FFM03, and FFM06. The models are build using data from detailed surface outcrop maps and the cored borehole record at Forsmark. The conceptual model for the Forsmark 2.2 geological revolves around the concept of orientation sets; for each fracture domain, other model parameters such as size and intensity are tied to the orientation sets. Two classes of orientation sets were described; Global sets, which are encountered everywhere in the model region, and Local sets, which represent highly localized stress environments. Orientation sets were described in terms of their general cardinal direction (NE, NW, etc). Two alternatives are presented for fracture size modeling: - the tectonic continuum approach (TCM, TCMF) described by coupled size-intensity scaling following power law distributions
Geological discrete-fracture network model (version 1) for the Olkiluoto site, Finland

International Nuclear Information System (INIS)

Fox, A.; Buoro, A.; Dahlbo, K.; Wiren, L.

2009-10-01

This report describes the methods, analyses, and conclusions of the modelling team in the production of a discrete-fracture network (DFN) model for the Olkiluoto Site in Finland. The geological DFN is a statistical model for stochastically simulating rock fractures and minor faults at a scale ranging from approximately 0.05 m to approximately 500 m; an upper scale limit is not expressly defined, but the DFN model explicitly excludes structures at deformation-zone scales (∼ 500 m) and larger. The DFN model is presented as a series of tables summarizing probability distributions for several parameters necessary for fracture modelling: fracture orientation, fracture size, fracture intensity, and associated spatial constraints. The geological DFN is built from data collected during site characterization (SC) activities at Olkiluoto, which is currently planned to function as a final deep geological repository for spent fuel and nuclear waste from the Finnish nuclear power program. Data used in the DFN analyses include fracture maps from surface outcrops and trenches (as of July 2007), geological and structural data from cored boreholes (as of July 2007), and fracture information collected during the construction of the main tunnels and shafts at the ONKALO laboratory (January 2008). The modelling results suggest that the rock volume at Olkiluoto surrounding the ONKALO tunnel can be separated into three distinct volumes (fracture domains): an upper block, an intermediate block, and a lower block. The three fracture domains are bounded horizontally and vertically by large deformation zones. Fracture properties, such as fracture orientation and relative orientation set intensity, vary between fracture domains. The rock volume at Olkiluoto is dominated by three distinct fracture sets: subhorizontally-dipping fractures striking north-northeast and dipping to the east, a subvertically-dipping fracture set striking roughly north-south, and a subverticallydipping fracture set
Geological discrete fracture network model for the Olkiluoto site, Eurajoki, Finland. Version 2.0

International Nuclear Information System (INIS)

Fox, A.; Forchhammer, K.; Pettersson, A.; La Pointe, P.; Lim, D-H.

2012-06-01

This report describes the methods, analyses, and conclusions of the modeling team in the production of the 2010 revision to the geological discrete fracture network (DFN) model for the Olkiluoto Site in Finland. The geological DFN is a statistical model for stochastically simulating rock fractures and minor faults at a scale ranging from approximately 0.05 m to approximately 565m; deformation zones are expressly excluded from the DFN model. The DFN model is presented as a series of tables summarizing probability distributions for several parameters necessary for fracture modeling: fracture orientation, fracture size, fracture intensity, and associated spatial constraints. The geological DFN is built from data collected during site characterization (SC) activities at Olkiluoto, which is selected to function as a final deep geological repository for spent fuel and nuclear waste from the Finnish nuclear power program. Data used in the DFN analyses include fracture maps from surface outcrops and trenches, geological and structural data from cored drillholes, and fracture information collected during the construction of the main tunnels and shafts at the ONKALO laboratory. Unlike the initial geological DFN, which was focused on the vicinity of the ONKALO tunnel, the 2010 revisions present a model parameterization for the entire island. Fracture domains are based on the tectonic subdivisions at the site (northern, central, and southern tectonic units) presented in the Geological Site Model (GSM), and are further subdivided along the intersection of major brittle-ductile zones. The rock volume at Olkiluoto is dominated by three distinct fracture sets: subhorizontally-dipping fractures striking north-northeast and dipping to the east that is subparallel to the mean bedrock foliation direction, a subvertically-dipping fracture set striking roughly north-south, and a subvertically-dipping fracture set striking approximately east-west. The subhorizontally-dipping fractures
Geological discrete fracture network model for the Olkiluoto site, Eurajoki, Finland. Version 2.0

Energy Technology Data Exchange (ETDEWEB)

Fox, A.; Forchhammer, K.; Pettersson, A. [Golder Associates AB, Stockholm (Sweden); La Pointe, P.; Lim, D-H. [Golder Associates Inc. (Finland)

2012-06-15

This report describes the methods, analyses, and conclusions of the modeling team in the production of the 2010 revision to the geological discrete fracture network (DFN) model for the Olkiluoto Site in Finland. The geological DFN is a statistical model for stochastically simulating rock fractures and minor faults at a scale ranging from approximately 0.05 m to approximately 565m; deformation zones are expressly excluded from the DFN model. The DFN model is presented as a series of tables summarizing probability distributions for several parameters necessary for fracture modeling: fracture orientation, fracture size, fracture intensity, and associated spatial constraints. The geological DFN is built from data collected during site characterization (SC) activities at Olkiluoto, which is selected to function as a final deep geological repository for spent fuel and nuclear waste from the Finnish nuclear power program. Data used in the DFN analyses include fracture maps from surface outcrops and trenches, geological and structural data from cored drillholes, and fracture information collected during the construction of the main tunnels and shafts at the ONKALO laboratory. Unlike the initial geological DFN, which was focused on the vicinity of the ONKALO tunnel, the 2010 revisions present a model parameterization for the entire island. Fracture domains are based on the tectonic subdivisions at the site (northern, central, and southern tectonic units) presented in the Geological Site Model (GSM), and are further subdivided along the intersection of major brittle-ductile zones. The rock volume at Olkiluoto is dominated by three distinct fracture sets: subhorizontally-dipping fractures striking north-northeast and dipping to the east that is subparallel to the mean bedrock foliation direction, a subvertically-dipping fracture set striking roughly north-south, and a subvertically-dipping fracture set striking approximately east-west. The subhorizontally-dipping fractures
Geological discrete fracture network model for the Laxemar site. Site Descriptive Modelling. SDM-Site Laxemar

Energy Technology Data Exchange (ETDEWEB)

La Pointe, Paul; Fox, Aaron (Golder Associates Inc (United States)); Hermanson, Jan; Oehman, Johan (Golder Associates AB, Stockholm (Sweden))

2008-12-15

The Swedish Nuclear Fuel and Waste Management Company (SKB) is performing site characterization at two different locations, Forsmark and Laxemar, in order to locate a site for a final geologic repository for spent nuclear fuel. The program is built upon the development of Site Descriptive Models (SDMs) at specific timed data freezes. Each SDM is formed from discipline-specific reports from across the scientific spectrum. This report describes the methods, analyses, and conclusions of the modelling team in the production of the SDM-Site Laxemar geological discrete-fracture network (DFN) model. The DFN builds upon the work of other geological models, including the deformation zone and rock domain models. The geological DFN is a statistical model for stochastically simulating rock fractures and minor deformation zones at a scale of less than 1,000 m (the lower cut-off of the DZ models). The geological DFN is valid within six distinct fracture domains inside the Laxemar local model subarea: FSM{sub C}, FSM{sub E}W007, FSM{sub N}, FSM{sub N}E005, FSM{sub S}, and FSM{sub W}. The models are built using data from detailed surface outcrop maps, geophysical lineament maps, and the cored borehole record at Laxemar. The conceptual model for the SDM-Site Laxemar geological DFN model revolves around the identification of fracture domains based on relative fracture set intensities, orientation clustering, and the regional tectonic framework (including deformation zones). A single coupled fracture size/fracture intensity concept (the Base Model) based on a Pareto (power-law) distribution for fracture sizes was chosen as the recommended parameterisation. A slew of alternative size-intensity models were also carried through the fracture analyses and into the uncertainty and model verification analyses. Uncertainty is modelled by analysing the effects on fracture intensity (P32) that alternative model cases can have. Uncertainty is parameterised as a ratio between the P32 of the
Geological discrete fracture network model for the Laxemar site. Site Descriptive Modelling. SDM-Site Laxemar

International Nuclear Information System (INIS)

La Pointe, Paul; Fox, Aaron; Hermanson, Jan; Oehman, Johan

2008-10-01

The Swedish Nuclear Fuel and Waste Management Company (SKB) is performing site characterization at two different locations, Forsmark and Laxemar, in order to locate a site for a final geologic repository for spent nuclear fuel. The program is built upon the development of Site Descriptive Models (SDMs) at specific timed data freezes. Each SDM is formed from discipline-specific reports from across the scientific spectrum. This report describes the methods, analyses, and conclusions of the modelling team in the production of the SDM-Site Laxemar geological discrete-fracture network (DFN) model. The DFN builds upon the work of other geological models, including the deformation zone and rock domain models. The geological DFN is a statistical model for stochastically simulating rock fractures and minor deformation zones at a scale of less than 1,000 m (the lower cut-off of the DZ models). The geological DFN is valid within six distinct fracture domains inside the Laxemar local model subarea: FSM C , FSM E W007, FSM N , FSM N E005, FSM S , and FSM W . The models are built using data from detailed surface outcrop maps, geophysical lineament maps, and the cored borehole record at Laxemar. The conceptual model for the SDM-Site Laxemar geological DFN model revolves around the identification of fracture domains based on relative fracture set intensities, orientation clustering, and the regional tectonic framework (including deformation zones). A single coupled fracture size/fracture intensity concept (the Base Model) based on a Pareto (power-law) distribution for fracture sizes was chosen as the recommended parameterisation. A slew of alternative size-intensity models were also carried through the fracture analyses and into the uncertainty and model verification analyses. Uncertainty is modelled by analysing the effects on fracture intensity (P32) that alternative model cases can have. Uncertainty is parameterised as a ratio between the P32 of the alternative model and the P
Modelling of 3D fractured geological systems - technique and application

Science.gov (United States)

Cacace, M.; Scheck-Wenderoth, M.; Cherubini, Y.; Kaiser, B. O.; Bloecher, G.

2011-12-01

All rocks in the earth's crust are fractured to some extent. Faults and fractures are important in different scientific and industry fields comprising engineering, geotechnical and hydrogeological applications. Many petroleum, gas and geothermal and water supply reservoirs form in faulted and fractured geological systems. Additionally, faults and fractures may control the transport of chemical contaminants into and through the subsurface. Depending on their origin and orientation with respect to the recent and palaeo stress field as well as on the overall kinematics of chemical processes occurring within them, faults and fractures can act either as hydraulic conductors providing preferential pathways for fluid to flow or as barriers preventing flow across them. The main challenge in modelling processes occurring in fractured rocks is related to the way of describing the heterogeneities of such geological systems. Flow paths are controlled by the geometry of faults and their open void space. To correctly simulate these processes an adequate 3D mesh is a basic requirement. Unfortunately, the representation of realistic 3D geological environments is limited by the complexity of embedded fracture networks often resulting in oversimplified models of the natural system. A technical description of an improved method to integrate generic dipping structures (representing faults and fractures) into a 3D porous medium is out forward. The automated mesh generation algorithm is composed of various existing routines from computational geometry (e.g. 2D-3D projection, interpolation, intersection, convex hull calculation) and meshing (e.g. triangulation in 2D and tetrahedralization in 3D). All routines have been combined in an automated software framework and the robustness of the approach has been tested and verified. These techniques and methods can be applied for fractured porous media including fault systems and therefore found wide applications in different geo-energy related
Primary drainage in geological fractures: Effects of aperture variability and wettability

Science.gov (United States)

Yang, Z.; Méheust, Y.; Neuweiler, I.

2017-12-01

Understanding and controlling fluid-fluid displacement in porous and fractured media is a key asset for many practical applications, such as the geological storage of CO2, hydrocarbon recovery, groundwater remediation, etc. We numerically investigate fluid-fluid displacement in rough-walled fractures with a focus on the combined effect of wettability, the viscous contrast between the two fluids, and fracture surface topography on drainage patterns and interface growth. A model has been developed to simulate the dynamic displacement of one fluid by another immiscible one in a rough geological fracture; the model takes both capillary and viscous forces into account. Capillary pressures at the fluid-fluid interface are calculated based on the Young-Laplace equation using the two principal curvatures (aperture-induced curvature and in-plane curvature) [1], while viscous forces are calculated by continuously solving the fluid pressure field in the fracture. The aperture field of a fracture is represented by a spatially correlated random field, with a power spectral density of the fracture wall topographies scaling as a power law, and a cutoff wave-length above which the Fourier modes of the two walls are identical [2]. We consider flow scenarios with both rectangular and radial configurations. Results show that the model is able to produce displacement patterns of compact displacement, capillary fingering, and viscous fingering, as well as the transitions between them. Both reducing the aperture variability and increasing the contact angle (from drainage to weak imbibition) can stabilize the displacement due to the influence of the in-plane curvature, an effect analogous to that of the cooperative pore filling in porous media. These results suggest that for geometries typical of geological fractures we can extend the phase diagram in the parameter space of capillary number and mobility ratio by another dimension to take into account the combined effect of wettability
Fracture Sealing in Shales: Geological and Geochemical Factors

International Nuclear Information System (INIS)

Cathelineau, Michel

2001-01-01

The so-called self-sealing processes can be re-examined at the light of geological and geochemical consideration about the past history of the rocks. The concept of 'self sealing' needs to consider the formation and the sealing of fractures, especially three main stages: (i) the initiation of the fracture (development of micro-cracks initiated from previous heterogeneities up to fracturing), ii) the fracturing processes which occur generally at depth in presence of a fluid phase, iii) the healing or sealing of the fractures which corresponds basically to two main processes: a restoration of the initial permeability of the rock block by reducing the transmissivity of the discontinuity down to values equivalent to that of the homogeneous medium before fracturing, or the sealing of the open discontinuity by precipitation of newly formed minerals. In the latter case, the evolution of the open fracture is driven by re-arrangement of particles or precipitation of newly formed material, either by dissolution/crystallisation processes or by crystallisation from the percolating fluids (advective processes). Such processes are governed by chemical processes, especially the rate of precipitation of minerals which depends of the degree of saturation with respect to the mineral, and the kinetics of precipitation. (author)
The use of geological data from pilot holes for predicting FPI (full perimeter intersection) fractures

International Nuclear Information System (INIS)

Joutsen, A.

2012-02-01

Posiva Oy is responsible for preparation of final disposal of spent nuclear fuel in Olkiluoto. The knowledge about existing network of fractures is important for the safety and feasibility of the final repository. The bedrock properties essential for safety case are analyzed in investigations of Rock Suitability Criteria (RSC). One subtask in RSC is avoidance of large (long) fractures adjacent to disposal holes. The long fractures have been defined in tunnel mapping to indicate tunnel cross-cutting fractures (TCF) or full perimeter intersections (FPI). The purpose for this study was to evaluate the possibility of recognizing FPIs from drill cores by their geological properties. The study was carried out by correlating FPIs mapped from the ONKALO tunnel to the pilot holes logging data with a view of finding out which fracture in the pilot hole corresponds to the FPI in the tunnel. It was also estimated what kind of geological properties does FPIs commonly have in the tunnel and how does these properties differ from the FPI correlated pilot hole fractures. The data sources for this study are the pilot holes from ONK-PH8 to ONK-PH14 and the systematic geological mapping data. The FPIs used in this study usually follow the general trends of the fracturing in the Olkiluoto bedrock. The fracture surface profiles are principally undulating and a striation can be often seen on the fracture surfaces. The FPIs are frequently moderately to intensely altered with diverse filling mineralogy and thick fracture fillings in comparison to the regular fractures. The FPI correlated pilot hole fractures have slightly different properties in comparison to the FPIs. These fractures have wider range of different fracture surface profiles and are slightly less altered than the FPIs. Filling mineralogy follows the trends of the FPIs but filling thicknesses are thinner. These differences probably occur because of the variable uncertainties related to the correlation and to the fact that the
The use of geological data from pilot holes for predicting FPI (full perimeter intersection) fractures

Energy Technology Data Exchange (ETDEWEB)

Joutsen, A.

2012-02-15

Posiva Oy is responsible for preparation of final disposal of spent nuclear fuel in Olkiluoto. The knowledge about existing network of fractures is important for the safety and feasibility of the final repository. The bedrock properties essential for safety case are analyzed in investigations of Rock Suitability Criteria (RSC). One subtask in RSC is avoidance of large (long) fractures adjacent to disposal holes. The long fractures have been defined in tunnel mapping to indicate tunnel cross-cutting fractures (TCF) or full perimeter intersections (FPI). The purpose for this study was to evaluate the possibility of recognizing FPIs from drill cores by their geological properties. The study was carried out by correlating FPIs mapped from the ONKALO tunnel to the pilot holes logging data with a view of finding out which fracture in the pilot hole corresponds to the FPI in the tunnel. It was also estimated what kind of geological properties does FPIs commonly have in the tunnel and how does these properties differ from the FPI correlated pilot hole fractures. The data sources for this study are the pilot holes from ONK-PH8 to ONK-PH14 and the systematic geological mapping data. The FPIs used in this study usually follow the general trends of the fracturing in the Olkiluoto bedrock. The fracture surface profiles are principally undulating and a striation can be often seen on the fracture surfaces. The FPIs are frequently moderately to intensely altered with diverse filling mineralogy and thick fracture fillings in comparison to the regular fractures. The FPI correlated pilot hole fractures have slightly different properties in comparison to the FPIs. These fractures have wider range of different fracture surface profiles and are slightly less altered than the FPIs. Filling mineralogy follows the trends of the FPIs but filling thicknesses are thinner. These differences probably occur because of the variable uncertainties related to the correlation and to the fact that the
The influence of open fracture anisotropy on CO2 movement within geological storage complexes

Science.gov (United States)

Bond, C. E.; Wightman, R.; Ringrose, P. S.

2012-12-01

Carbon mitigation through the geological storage of carbon dioxide is dependent on the ability of geological formations to store CO2 trapping it within a geological storage complex. Secure long-term containment needs to be demonstrated, due to both political and social drivers, meaning that this containment must be verifiable over periods of 100-105 years. The effectiveness of sub-surface geological storage systems is dependent on trapping CO2 within a volume of rock and is reliant on the integrity of the surrounding rocks, including their chemical and physical properties, to inhibit migration to the surface. Oil and gas reservoir production data, and field evidence show that fracture networks have the potential to act as focused pathways for fluid movement. Fracture networks can allow large volumes of fluid to migrate to the surface within the time scales of interest. In this paper we demonstrate the importance of predicting the effects of fracture networks in storage, using a case study from the In Salah CO2 storage site, and show how the fracture permeability is closely controlled by the stress regime that determines the open fracture network. Our workflow combines well data of imaged fractures, with a discrete fracture network (DFN) model of tectonically induced fractures, within the horizon of interest. The modelled and observed fractures have been compared and combined with present day stress data to predict the open fracture network and its implications for anisotropic movement of CO2 in the sub-surface. The created fracture network model has been used to calculate the 2D permeability tensor for the reservoir for two scenarios: 1) a model in which all fractures are permeable, based on the whole DFN model and 2) those fractures determined to be in dilatational failure under the present day stress regime, a sub-set of the DFN. The resulting permeability anisotropy tensors show distinct anisotropies for the predicted CO2 movement within the reservoir. These
Use of integrated geologic and geophysical information for characterizing the structure of fracture systems at the US/BK Site, Grimsel Laboratory, Switzerland

International Nuclear Information System (INIS)

Martel, S.J.; Peterson, J.E. Jr.

1990-05-01

Fracture systems form the primary fluid flow paths in a number of rock types, including some of those being considered for high level nuclear waste repositories. In some cases, flow along fractures must be modeled explicitly as part of a site characterization effort. Fractures commonly are concentrated in fracture zones, and even where fractures are seemingly ubiquitous, the hydrology of a site can be dominated by a few discrete fracture zones. We have implemented a site characterization methodology that combines information gained from geophysical and geologic investigations. The general philosophy is to identify and locate the major fracture zones, and then to characterize their systematics. Characterizing the systematics means establishing the essential and recurring patterns in which fractures are organized within the zones. We make a concerted effort to use information on the systematics of the fracture systems to link the site-specific geologic, borehole and geophysical information. This report illustrates how geologic and geophysical information on geologic heterogeneities can be integrated to guide the development of hydrologic models. The report focuses on fractures, a particularly common type of geologic heterogeneity. However, many aspects of the methodology we present can be applied to other geologic heterogeneities as well. 57 refs., 40 figs., 1 tab
Monte Carlo simulation of radioactive contaminant transport in fractured geologic media: Disorder and long-range correlations

International Nuclear Information System (INIS)

Mukhopadhyay, S.; Cushman, J.H.

1997-01-01

The geologic media near Yucca mountain site consist of fractured welded tuffs along with less fractured unwelded tuff. Numerical simulation of flow and transport in such media poses a number of challenging problems, due mainly to the heterogeneities and disorder in the media. In addition, because of different dominant transport mechanisms in different regions of the media, investigations need to be carried out at different time-scales. Time-marching will pose a considerable problem in analyzing such multi-scale transient problems. The authors develop a field-scale network model of fractures and study transport of radionuclides through geologic media as a function of disorder and correlated fracture-permeabilities
Correlation Between Fracture Network Properties and Stress Variability in Geological Media

Science.gov (United States)

Lei, Qinghua; Gao, Ke

2018-05-01

We quantitatively investigate the stress variability in fractured geological media under tectonic stresses. The fracture systems studied include synthetic fracture networks following power law length scaling and natural fracture patterns based on outcrop mapping. The stress field is derived from a finite-discrete element model, and its variability is analyzed using a set of mathematical formulations that honor the tensorial nature of stress data. We show that local stress perturbation, quantified by the Euclidean distance of a local stress tensor to the mean stress tensor, has a positive, linear correlation with local fracture intensity, defined as the total fracture length per unit area within a local sampling window. We also evaluate the stress dispersion of the entire stress field using the effective variance, that is, a scalar-valued measure of the overall stress variability. The results show that a well-connected fracture system under a critically stressed state exhibits strong local and global stress variabilities.
Behavior of rare earth elements in fractured aquifers: an application to geological disposal criteria for radioactive waste

International Nuclear Information System (INIS)

Lee, Seung Gu; Kim, Yong Je; Lee, Kil Yong; Kim, Kun Han

2003-01-01

An understanding of the geochemistry of potential host rocks is very important in the site evaluation for construction of an underground geologic repository for radioactive waste. Because of similar valence and ionic radii and high similarity in electronic structure with trivalent actinides (such as Am 3+ and Cm 3+ ), the rare earth elements (REEs) have been used to predict the behavior of actinide-series elements in solution (Runde et al., 1992). For Am and Cm, which occur only in the trivalent states in most waste-disposal repository environments, the analogy with the REEs is particularly relevant. In order to discuss the behavior of REEs in geological media and to deduce the behavior of actinides in geological environments based on the REE abundance, and to provide an useful tool in deciding an optimum geological condition for radioactive disposal, we estimated the REE abundance from various kinds of fractured rock type. In fractured granitic aquifer, chondrite-normalized REE pattern show Eu positive anomaly due to fracture-filling calcite precipitation. However, in fractured meta-basaltic and volcanic tuffaceous aquifer, REE pattern do not show the change of Eu anomaly due to fracture-filling calcite precipitation. Eu shows very similar properties such as cohesive energy, ionic radii with coordination number compared to Am. Therefore, if we consider the Eu behavior in fractured rocks and the similar physical/chemical properties of Eu and Am, together, our results strongly suggest that Eu is a very useful analogue for predicting the behavior of Am in geological environment
Wellbore cement fracture evolution at the cement–basalt caprock interface during geologic carbon sequestration

Energy Technology Data Exchange (ETDEWEB)

Jung, Hun Bok; Kabilan, Senthil; Carson, James P.; Kuprat, Andrew P.; Um, Wooyong; Martin, Paul F.; Dahl, Michael E.; Kafentzis, Tyler A.; Varga, Tamas; Stephens, Sean A.; Arey, Bruce W.; Carroll, KC; Bonneville, Alain; Fernandez, Carlos A.

2014-08-07

Composite Portland cement-basalt caprock cores with fractures, as well as neat Portland cement columns, were prepared to understand the geochemical and geomechanical effects on the integrity of wellbores with defects during geologic carbon sequestration. The samples were reacted with CO2-saturated groundwater at 50 ºC and 10 MPa for 3 months under static conditions, while one cement-basalt core was subjected to mechanical stress at 2.7 MPa before the CO2 reaction. Micro-XRD and SEM-EDS data collected along the cement-basalt interface after 3-month reaction with CO2-saturated groundwater indicate that carbonation of cement matrix was extensive with the precipitation of calcite, aragonite, and vaterite, whereas the alteration of basalt caprock was minor. X-ray microtomography (XMT) provided three-dimensional (3-D) visualization of the opening and interconnection of cement fractures due to mechanical stress. Computational fluid dynamics (CFD) modeling further revealed that this stress led to the increase in fluid flow and hence permeability. After the CO2-reaction, XMT images displayed that calcium carbonate precipitation occurred extensively within the fractures in the cement matrix, but only partially along the fracture located at the cement-basalt interface. The 3-D visualization and CFD modeling also showed that the precipitation of calcium carbonate within the cement fractures after the CO2-reaction resulted in the disconnection of cement fractures and permeability decrease. The permeability calculated based on CFD modeling was in agreement with the experimentally determined permeability. This study demonstrates that XMT imaging coupled with CFD modeling represent a powerful tool to visualize and quantify fracture evolution and permeability change in geologic materials and to predict their behavior during geologic carbon sequestration or hydraulic fracturing for shale gas production and enhanced geothermal systems.
Self-sealing of Fractures in Argillaceous Formations in the Context of Geological Disposal of Radioactive Waste

International Nuclear Information System (INIS)

2010-01-01

Disposal of high-level radioactive waste and spent nuclear fuel in engineered facilities, or repositories, located deep underground in suitable geological formations is being developed worldwide as the reference solution to protect humans and the environment both now and in the future. Assessing the long-term safety of geological disposal requires developing a comprehensive understanding of the geological environment. The transport pathways are key to this understanding. Of particular interest are fractures in the host rock, which may be either naturally occurring or induced, for example, during the construction of engineered portions of a repository. Such fractures could provide pathways for migration of contaminants. In argillaceous (clay) formations, there is evidence that, over time, fractures can become less conductive and eventually hydraulically insignificant. This process is commonly termed 'self-sealing'. The capacity for self-sealing relates directly to the function of clay host rocks as migration barriers and, consequently, to the safety of deep repositories in those geological settings. This report - conducted under the auspices of the NEA Clay Club - reviews the evidence and mechanisms for self-sealing properties of clays and evaluates their relevance to geological disposal. Results from laboratory tests, field investigations and geological analogues are considered. The evidence shows that, for many types of argillaceous formations, the understanding of self-sealing has progressed to a level that could justify its inclusion in performance assessments for geological repositories. (authors)

A preliminary study on the regional fracture systems for deep geological disposal of high level radioactive waste in Korea

Energy Technology Data Exchange (ETDEWEB)

Kim, Chun Soo; Bae, Dae Seok; Kim, Kyung Su; Koh, Young Kown; Park, Byoung Yoon [Korea Atomic Energy Research Institute, Taejeon (Korea)

2000-03-01

For the deep geological disposal of high-level radioactive waste, it is essential to characterize the fracture system in rock mass which has a potential pathways of nuclide. Currently, none of research results are in classification and detailed properties for the fracture system in Korea. This study aims to classify and describe the regional fracture system in lithological and geotectonical point of view using literature review, shaded relief map, and aeromagnetic survey data. This report contains the following: - Theoretical review of the fracture development mechanism. - Overall fault and fracture map. - Geological description on the distributional characteristics of faults and fractures(zone) in terms of lithological domain and tectonical province. 122 refs., 22 figs., 4 tabs. (Author)
A Rock Mechanics and Coupled Hydro mechanical Analysis of Geological Repository of High Level Nuclear Waste in Fractured Rocks

International Nuclear Information System (INIS)

Min, Kibok

2011-01-01

This paper introduces a few case studies on fractured hard rock based on geological data from Sweden, Korea is one of a few countries where crystalline rock is the most promising rock formation as a candidate site of geological repository of high level nuclear waste. Despite the progress made in the area of rock mechanics and coupled hydro mechanics, extensive site specific study on multiple candidate sites is essential in order to choose the optimal site. For many countries concerned about the safe isolation of nuclear wastes from the biosphere, disposal in a deep geological formation is considered an attractive option. In geological repository, thermal loading continuously disturbs the repository system in addition to disturbances a recent development in rock mechanics and coupled hydro mechanical study using DFN(Discrete Fracture Network) - DEM(Discrete Element Method) approach mainly applied in hard, crystalline rock containing numerous fracture which are main sources of deformation and groundwater flow
Geomass: geological modelling analysis and simulation software for the characterisation of fractured hard rock environments

International Nuclear Information System (INIS)

White, M.J.; Humm, J.P.; Todaka, N.; Takeuchi, S.

1998-01-01

This paper presents the development and functionality of a suite of applications which are being developed to support the geological investigations in the Tono URL. GEOMASS will include 3D geological modelling, 3D fluid flow and solute transport and 3D visualisation capabilities. The 3D geological modelling in GEOMASS will be undertaken using a commercially available 3D geological modelling system, EarthVision. EarthVision provides 3D mapping, interpolation, analysis and well planning software. It is being used in the GEOMASS system to provide the geological framework (structure of the tectonic faults and stratigraphic and lithological contacts) to the 3D flow code. It is also being used to gather the geological data into a standard format for use throughout the investigation programme. The 3D flow solver to be used in GEOMASS is called Frac-Affinity. Frac-Affinity models the 3D geometry of the flow system as a hybrid medium, in which the rock contains both permeable, intact rock and fractures. Frac-Affinity also performs interpolation of heterogeneous rock mass property data using a fractal based approach and the generation of stochastic fracture networks. The code solves for transient flow over a user defined sub-region of the geological framework supplied by EarthVision. The results from Frac-Affinity are passed back to EarthVision so that the flow simulation can be visualized alongside the geological structure. This work-flow allows rapid assessment of the role of geological features in controlling flow. This paper will present the concepts and approach of GEOMASS and illustrate the practical application of GEOMASS using data from Tono
Approaches to large scale unsaturated flow in heterogeneous, stratified, and fractured geologic media

International Nuclear Information System (INIS)

Ababou, R.

1991-08-01

This report develops a broad review and assessment of quantitative modeling approaches and data requirements for large-scale subsurface flow in radioactive waste geologic repository. The data review includes discussions of controlled field experiments, existing contamination sites, and site-specific hydrogeologic conditions at Yucca Mountain. Local-scale constitutive models for the unsaturated hydrodynamic properties of geologic media are analyzed, with particular emphasis on the effect of structural characteristics of the medium. The report further reviews and analyzes large-scale hydrogeologic spatial variability from aquifer data, unsaturated soil data, and fracture network data gathered from the literature. Finally, various modeling strategies toward large-scale flow simulations are assessed, including direct high-resolution simulation, and coarse-scale simulation based on auxiliary hydrodynamic models such as single equivalent continuum and dual-porosity continuum. The roles of anisotropy, fracturing, and broad-band spatial variability are emphasized. 252 refs
Solute transport in a single fracture involving an arbitrary length decay chain with rock matrix comprising different geological layers.

Science.gov (United States)

Mahmoudzadeh, Batoul; Liu, Longcheng; Moreno, Luis; Neretnieks, Ivars

2014-08-01

A model is developed to describe solute transport and retention in fractured rocks. It accounts for advection along the fracture, molecular diffusion from the fracture to the rock matrix composed of several geological layers, adsorption on the fracture surface, adsorption in the rock matrix layers and radioactive decay-chains. The analytical solution, obtained for the Laplace-transformed concentration at the outlet of the flowing channel, can conveniently be transformed back to the time domain by the use of the de Hoog algorithm. This allows one to readily include it into a fracture network model or a channel network model to predict nuclide transport through channels in heterogeneous fractured media consisting of an arbitrary number of rock units with piecewise constant properties. More importantly, the simulations made in this study recommend that it is necessary to account for decay-chains and also rock matrix comprising at least two different geological layers, if justified, in safety and performance assessment of the repositories for spent nuclear fuel. Copyright © 2014 Elsevier B.V. All rights reserved.
Characterizing fractured plutonic rocks of the Canadian shield for deep geological disposal of Canada's radioactive wastes

International Nuclear Information System (INIS)

Lodha, G.S.; Davison, C.C.; Gascoyne, M.

1998-01-01

Since 1978 AECL has been investigating plutonic rocks of the Canadian Shield as a potential medium for the disposal of Canada's nuclear fuel waste. During the last two years this study has been continued as part of Ontario Hydro's used fuel disposal program. Methods have been developed for characterizing the geotechnical conditions at the regional scale of the Canadian Shield as well as for characterizing conditions at the site scale and the very near-field scale needed for locating and designing disposal vault rooms and waste emplacement areas. The Whiteshell Research Area (WRA) and the Underground Research Laboratory (URL) in southeastern Manitoba have been extensively used to develop and demonstrate the different scales of characterization methods. At the regional scale, airborne magnetic and electromagnetic surveys combined with LANDSAT 5 and surface gravity survey data have been helpful in identifying boundaries of the plutonic rocks , overburden thicknesses, major lineaments that might be geological structures, lithological contacts and depths of the batholiths. Surface geological mapping of exposed rock outcrops, combined with surface VLF/EM, radar and seismic reflection surveys were useful in identifying the orientation and depth continuity of low-dipping fracture zones beneath rock outcrops to a depth of 500 to 1000 m. The surface time-domain EM method has provided encouraging results for identifying the depth of highly saline pore waters. The regional site scale investigations at the WRA included the drilling of twenty deep boreholes (> 500 m) at seven separate study areas. Geological core logging combined with borehole geophysical logging, TV/ATV logging, flowmeter logging and full waveform sonic logging in these boreholes helped to confirm the location of hydro geologically important fractures, orient cores and infer the relative permeability of some fracture zones. Single-hole radar and crosshole seismic tomography surveys were useful to establish the
Diffusion Dominant Solute Transport Modelling in Fractured Media Under Deep Geological Environment - 12211

Energy Technology Data Exchange (ETDEWEB)

Kwong, S. [National Nuclear Laboratory (United Kingdom); Jivkov, A.P. [Research Centre for Radwaste and Decommissioning and Modelling and Simulation Centre, University of Manchester (United Kingdom)

2012-07-01

Deep geologic disposal of high activity and long-lived radioactive waste is gaining increasing support in many countries, where suitable low permeability geological formation in combination with engineered barriers are used to provide long term waste contaminant and minimise the impacts to the environment and risk to the biosphere. This modelling study examines the solute transport in fractured media under low flow velocities that are relevant to a deep geological environment. In particular, reactive solute transport through fractured media is studied using a 2-D model, that considers advection and diffusion, to explore the coupled effects of kinetic and equilibrium chemical processes. The effects of water velocity in the fracture, matrix porosity and diffusion on solute transport are investigated and discussed. Some illustrative modelled results are presented to demonstrate the use of the model to examine the effects of media degradation on solute transport, under the influences of hydrogeological (diffusion dominant) and microbially mediated chemical processes. The challenges facing the prediction of long term degradation such as cracks evolution, interaction and coalescence are highlighted. The potential of a novel microstructure informed modelling approach to account for these effects is discussed, particularly with respect to investigating multiple phenomena impact on material performance. The GRM code is used to examine the effects of media degradation for a geological waste disposal package, under the combined hydrogeological (diffusion dominant) and chemical effects in low groundwater flow conditions that are typical of deep geological disposal systems. An illustrative reactive transport modelling application demonstrates the use of the code to examine the interplay of kinetic controlled biogeochemical reactive processes with advective and diffusive transport, under the influence of media degradation. The initial model results are encouraging which show the
Geometry-coupled reactive fluid transport at the fracture scale -Application to CO 2 geologic storage

KAUST Repository

Kim, Seunghee

2015-08-19

Water acidification follows CO2 injection and leads to reactive fluid transport through pores and rock fractures, with potential implications to reservoirs and wells in CO2 geologic storage and enhanced oil recovery. Kinetic rate laws for dissolution reactions in calcite and anorthite are combined with Navier-Stokes law and advection-diffusion transport to perform geometry-coupled numerical simulations in order to study the evolution of chemical reactions, species concentration and fracture morphology. Results are summarized as a function of two dimensionless parameters: the Damköhler number Da which is the ratio between advection and reaction times, and the transverse Peclet number Pe defined as the ratio between the time for diffusion across the fracture and the time for advection along the fracture. Reactant species are readily consumed near the inlet in a carbonate reservoir when the flow velocity is low (low transverse Peclet number and Da>10-1). At high flow velocities, diffusion fails to homogenize the concentration field across the fracture (high transverse Peclet number Pe>10-1). When the reaction rate is low as in anorthite reservoirs (Da<10-1) reactant species are more readily transported towards the outlet. At a given Peclet number, a lower Damköhler number causes the flow channel to experience a more uniform aperture enlargement along the length of the fracture. When the length-to-aperture ratio is sufficiently large, say l/d>30, the system response resembles the solution for 1-D reactive fluid transport. A decreased length-to-aperture ratio slows the diffusive transport of reactant species to the mineral fracture surface, and analyses of fracture networks must take into consideration both the length and slenderness of individual fractures in addition to Pe and Da numbers.
Geometry-coupled reactive fluid transport at the fracture scale -Application to CO 2 geologic storage

KAUST Repository

Kim, Seunghee; Santamarina, Carlos

2015-01-01

Water acidification follows CO2 injection and leads to reactive fluid transport through pores and rock fractures, with potential implications to reservoirs and wells in CO2 geologic storage and enhanced oil recovery. Kinetic rate laws for dissolution reactions in calcite and anorthite are combined with Navier-Stokes law and advection-diffusion transport to perform geometry-coupled numerical simulations in order to study the evolution of chemical reactions, species concentration and fracture morphology. Results are summarized as a function of two dimensionless parameters: the Damköhler number Da which is the ratio between advection and reaction times, and the transverse Peclet number Pe defined as the ratio between the time for diffusion across the fracture and the time for advection along the fracture. Reactant species are readily consumed near the inlet in a carbonate reservoir when the flow velocity is low (low transverse Peclet number and Da>10-1). At high flow velocities, diffusion fails to homogenize the concentration field across the fracture (high transverse Peclet number Pe>10-1). When the reaction rate is low as in anorthite reservoirs (Da<10-1) reactant species are more readily transported towards the outlet. At a given Peclet number, a lower Damköhler number causes the flow channel to experience a more uniform aperture enlargement along the length of the fracture. When the length-to-aperture ratio is sufficiently large, say l/d>30, the system response resembles the solution for 1-D reactive fluid transport. A decreased length-to-aperture ratio slows the diffusive transport of reactant species to the mineral fracture surface, and analyses of fracture networks must take into consideration both the length and slenderness of individual fractures in addition to Pe and Da numbers.
Mapping and analysis of geological fractures extracted by remote sensing on Landsat TM images, example of the Imilchil-Tounfite area (Central High Atlas, Morocco)

Energy Technology Data Exchange (ETDEWEB)

Alaoui, H. El; Moujahid, El; Ibouh, H.; Bachnou, A.; Babram, M. Ait; Harti, A. EI

2016-07-01

The use of remote sensing, in this research, can be summarized in mapping and statistical studies of lineaments on the satellites images of the Jurassic outcrops in the Imilchil-Tounfite area, Central High Atlas of Morocco. This is to apply various manual techniques for extracting lineaments from Landsat TM image. Analytical techniques used in this work are: the principal component analysis (PCA) applied to selective bands of the visible and infrared, which allows creating new images with better visual interpretation. Directional filters N0°, N45°, N90°, and N135° with a 5×5 matrix were used to enhance lineaments in the corresponding perpendicular directions, and therefore to obtain a good discrimination of those structures. Preliminary results highlight a dominant geological fracturing trending ENE/WSW with 52% of the total lineaments, a second fracture trending is WNW/ESE at 23%, a third fracture series trending NE/SW with 20% and finally, a minor series of fractures trending NW/SE with 5% of the total lineaments. Distribution and statistical relationship, between fractures and the affected surface on the one hand and the fracture length on the other hand, shows a network of well-structured fractures. The final lineament map constitutes a contribution to complete the geology and assisting the mining and hydrogeological prospection, in the Imilchil-Tounfite area. (Author)
The study of fracture mineralization and relationship with high level radioactive waste of deep geological repository

International Nuclear Information System (INIS)

Reyes, Cristina N.

2003-01-01

Extensive investigations of the Ordovician, Dinantian and Permo-Triassic rocks of the Sellafield area of northwest England were undertaken by United Kingdom Nirex Ltd. as a possible national site for geological disposal of intermediate and low-level radioactive waste. Very detailed studies of fracture mineralisation at Sellafield were thus put in hand by Nirex Ltd. and the results summarised by the British Geological Survey. Deep (up to 2 km) boreholes were put down with excellent core recovery. It is generally agreed that the most significant pathway for the escape of all but a very few radionuclides is by solution in and advection of groundwater. In this context, rock fracture systems are particularly important because they offer a potentially rapid pathway to the surface and the biosphere. One striking aspect of this work is that the fracture mineralisation seemingly records major and rapid fluctuations in redox conditions -sometimes during apparently continuous precipitation of cements (ferroan and non-ferroan calcites, dolomite). Carbonate cements record variations in Fe 2+ availability. Fe(III) precipitates also as oxide (hematite) and Fe(II) as sulphide (pyrite). This study focuses on these elements and valence states and also on Mn; another element susceptible to redox controls but known to respond differently from Fe. Shallow sub-surface stores or repositories would be more likely to have oxidising or fluctuating redox conditions. The mineralisation sequences documented at Sellafield are potentially promising in this context. Ferroan carbonate cements are sensitive indicators of later movement of oxidising ground waters. (author)
Geologic characterization of fractures as an aid to hydrologic modeling of the SCV block at the Stripa mine

International Nuclear Information System (INIS)

Martel, S.

1992-04-01

A series of hydrologic tests have been conducted at the Stripa research mine in Sweden to develop hydrologic characterization techniques for rock masses in which fractures form the primary flow paths. The structural studies reported here were conducted to aid in the hydrologic examination of a cubic block of granite with dimensions of 150 m on a side. This block (the SCV block) is located between the 310- and 460-m depth levels at the Stripa mine. This report describes and interprets the fracture system geology at Stripa as revealed in drift exposures, checks the interpretive model against borehole records and discusses the hydrologic implication of the model, and examines the likely effects of stress redistribution around a drift (the Validation drift) on inflow to the drift along a prominent fracture zone. (72 refs.) (au)
Improving Geologic and Engineering Models of Midcontinent Fracture and Karst-Modified Reservoirs Using New 3-D Seismic Attributes

Energy Technology Data Exchange (ETDEWEB)

Susan Nissen; Saibal Bhattacharya; W. Lynn Watney; John Doveton

2009-03-31

Our project goal was to develop innovative seismic-based workflows for the incremental recovery of oil from karst-modified reservoirs within the onshore continental United States. Specific project objectives were: (1) to calibrate new multi-trace seismic attributes (volumetric curvature, in particular) for improved imaging of karst-modified reservoirs, (2) to develop attribute-based, cost-effective workflows to better characterize karst-modified carbonate reservoirs and fracture systems, and (3) to improve accuracy and predictiveness of resulting geomodels and reservoir simulations. In order to develop our workflows and validate our techniques, we conducted integrated studies of five karst-modified reservoirs in west Texas, Colorado, and Kansas. Our studies show that 3-D seismic volumetric curvature attributes have the ability to re-veal previously unknown features or provide enhanced visibility of karst and fracture features compared with other seismic analysis methods. Using these attributes, we recognize collapse features, solution-enlarged fractures, and geomorphologies that appear to be related to mature, cockpit landscapes. In four of our reservoir studies, volumetric curvature attributes appear to delineate reservoir compartment boundaries that impact production. The presence of these compartment boundaries was corroborated by reservoir simulations in two of the study areas. Based on our study results, we conclude that volumetric curvature attributes are valuable tools for mapping compartment boundaries in fracture- and karst-modified reservoirs, and we propose a best practices workflow for incorporating these attributes into reservoir characterization. When properly calibrated with geological and production data, these attributes can be used to predict the locations and sizes of undrained reservoir compartments. Technology transfer of our project work has been accomplished through presentations at professional society meetings, peer-reviewed publications
Geology Forsmark. Site descriptive modelling Forsmark - stage 2.2

Energy Technology Data Exchange (ETDEWEB)

Stephens, Michael B. [Geological Survey of Sweden, Uppsala (Sweden); Fox, Aaron; La Pointe, Paul [Golder Associates Inc (United States); Simeonov, Assen [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden); Isaksson, Hans [GeoVista AB, Luleaa (Sweden); Hermanson, Jan; Oehman, Johan [Golder Associates AB, Stockholm (Sweden)

2007-10-15

The geological work during stage 2.2 has involved the development of deterministic models for rock domains (RFM) and deformation zones (ZFM), the identification and deterministic modelling of fracture domains (FFM) inside the candidate volume, i.e. the parts of rock domains that are not affected by deformation zones, and the development of statistical models for fractures and minor deformation zones (geological discrete fracture network modelling or geological DFN modelling). The geological DFN model addresses brittle structures at a scale of less than 1 km, which is the lower cut-off in the deterministic modelling of deformation zones. In order to take account of variability in data resolution, deterministic models for rock domains and deformation zones are presented in both regional and local model volumes, while the geological DFN model is valid within specific fracture domains inside the north-western part of the candidate volume, including the target volume. The geological modelling work has evaluated and made use of: A revised bedrock geological map at the ground surface. Geological and geophysical data from 21 cored boreholes and 33 percussion boreholes. Detailed mapping of fractures and rock units along nine excavations or large surface outcrops. Data bearing on the characterisation (including kinematics) of deformation zones. Complementary geochronological and other rock and fracture analytical data. Lineaments identified on the basis of airborne and high-resolution ground magnetic data. A reprocessing of both surface and borehole reflection seismic data. Seismic refraction data. The outputs of the deterministic modelling work are geometric models in RVS format and detailed property tables for rock domains and deformation zones, and a description of fracture domains. The outputs of the geological DFN modelling process are recommended parameters or statistical distributions that describe fracture set orientations, radius sizes, volumetric intensities
Geology Forsmark. Site descriptive modelling Forsmark - stage 2.2

International Nuclear Information System (INIS)

Stephens, Michael B.; Fox, Aaron; La Pointe, Paul; Simeonov, Assen; Isaksson, Hans; Hermanson, Jan; Oehman, Johan

2007-10-01

The geological work during stage 2.2 has involved the development of deterministic models for rock domains (RFM) and deformation zones (ZFM), the identification and deterministic modelling of fracture domains (FFM) inside the candidate volume, i.e. the parts of rock domains that are not affected by deformation zones, and the development of statistical models for fractures and minor deformation zones (geological discrete fracture network modelling or geological DFN modelling). The geological DFN model addresses brittle structures at a scale of less than 1 km, which is the lower cut-off in the deterministic modelling of deformation zones. In order to take account of variability in data resolution, deterministic models for rock domains and deformation zones are presented in both regional and local model volumes, while the geological DFN model is valid within specific fracture domains inside the north-western part of the candidate volume, including the target volume. The geological modelling work has evaluated and made use of: A revised bedrock geological map at the ground surface. Geological and geophysical data from 21 cored boreholes and 33 percussion boreholes. Detailed mapping of fractures and rock units along nine excavations or large surface outcrops. Data bearing on the characterisation (including kinematics) of deformation zones. Complementary geochronological and other rock and fracture analytical data. Lineaments identified on the basis of airborne and high-resolution ground magnetic data. A reprocessing of both surface and borehole reflection seismic data. Seismic refraction data. The outputs of the deterministic modelling work are geometric models in RVS format and detailed property tables for rock domains and deformation zones, and a description of fracture domains. The outputs of the geological DFN modelling process are recommended parameters or statistical distributions that describe fracture set orientations, radius sizes, volumetric intensities
Geological signatures of drillhole radar reflectors in ONKALO

International Nuclear Information System (INIS)

Doese, C.; Gustafsson, J.

2011-12-01

The geological signatures of radar reflectors in ONKALO have been evaluated as a subactivity within the Joint Work Programme 'Rock Suitability Criteria' strategies and methodology' between Svensk Kaernbraenslehantering AB and Posiva Oy. In addition to the geological signature, the usage of geophysical data to predict large fractures was evaluated. Pilot hole radar loggings were carried out using a RAMAC GPR-250 MHz dipole antenna. The radar data were evaluated and reflectors with known position and intersection angle to the pilot hole were correlated with fractures or foliation in the pilot hole and with Tunnel Crosscutting Fractures in the tunnel. This data served as in-data for the evaluation of the geological signatures of radar reflectors. The result of the evaluation is not univocal. Half of the reflectors could be explained by fractures in the pilot hole, but only about 10 % of the reflectors can be explained by Tunnel Crosscutting Fractures. Of these 10 %, 2/3 can also be explained by foliation, leaving only some 3 % of the total reflectors more unambiguously correlated with Tunnel Crosscutting Fractures. The fractures correlated with radar reflectors do not diverge much from other fractures. Fractures having intersection angles of 30 deg- 60 deg are more likely to be detected by radar relative to other. Other properties that seem to be overrepresented in fractures correlated with radar reflectors are quartz and/or graphite content, width ≥0.8 mm and higher alteration (J a ≥3), but the data is not unambiguous. (orig.)
Geological investigations for geological model of deep underground geoenvironment at the Mizunami Underground Research Laboratory (MIU)

International Nuclear Information System (INIS)

Tsuruta, Tadahiko; Tagami, Masahiko; Amano, Kenji; Matsuoka, Toshiyuki; Kurihara, Arata; Yamada, Yasuhiro; Koike, Katsuaki

2013-01-01

Japan Atomic Energy Agency (JAEA) is performing a geoscientific research project, the Mizunami Underground Research Laboratory (MIU) project, in order to establish scientific and technological basis for geological disposal of high-level radioactive wastes. The MIU is located in crystalline rock environment, in Mizunami City, central Japan. Field investigations include geological mapping, reflection seismic surveys, several borehole investigations and geological investigations in the research galleries to identify the distribution and heterogeneity of fractures and faults that are potential major flowpaths for groundwater. The results of these field investigations are synthesized and compiled for the purpose of geological modeling. The field investigations indicate that the Main Shaft at the MIU intersected low permeability NNW oriented faults. A high permeability fracture zone in the granite, a significant water inflow point, was observed in the Ventilation Shaft. Development of the geological model focusing 3D spatial relationships at different scales and evolution of the geoenvironment are underway. This paper describes geological investigations applied in the MIU project, focusing on the evaluation of their effectiveness to understand for deep underground geoenvironment. (author)
Effect of hydro mechanical coupling on natural fracture network formation in sedimentary basins

Science.gov (United States)

Ouraga, Zady; Guy, Nicolas; Pouya, Amade

2018-05-01

In sedimentary basin context, numerous phenomena, depending on the geological time span, can result in natural fracture network formation. In this paper, fracture network and dynamic fracture spacing triggered by significant sedimentation rate are studied considering mode I fracture propagation using a coupled hydro-mechanical numerical methods. The focus is put on synthetic geological structure under a constant sedimentation rate on its top. This model contains vertical fracture network initially closed and homogeneously distributed. The fractures are modelled with cohesive zone model undergoing damage and the flow is described by Poiseuille's law. The effect of the behaviour of the rock is studied and the analysis leads to a pattern of fracture network and fracture spacing in the geological layer.
History matching of large scale fractures to production data; Calage de la geometrie des reseaux de fractures aux donnees hydrodynamiques de production d'un champ petrolier

Energy Technology Data Exchange (ETDEWEB)

Jenni, S.

2005-01-01

Object based models are very helpful to represent complex geological media such as fractured reservoirs. For building realistic fracture networks, these models have to be constrained to both static (seismic, geomechanics, geology) and dynamic data (well tests and production history). In this report we present a procedure for the calibration of large-scale fracture networks to production history. The history matching procedure includes a realistic geological modeling, a parameterization method coherent with the geological model and allowing an efficient optimization. Fluid flow modeling is based on a double medium approach. The calibration procedure was applied to a semi-synthetic case based on a real fractured reservoir. The calibration to water-cut data was performed. (author)
Geological and petrological considerations relevant to the disposal of radioactive wastes by hydraulic fracturing: an example at the US Department of Energy's Oak Ridge National Laboratory

International Nuclear Information System (INIS)

Haase, C.S.

1982-01-01

At Oak Ridge National Laboratory the Pumpkin Valley Shale is used as a host formation for hydraulic-fracturing waste disposal. Determination of the relationships between the distribution of different lithologies and porosity-permeability trends within this host formation allows these properties, important to hydraulic-fracturing operations, to be related to measurable and mappable geological and petrological parameters. It also permits extrapolation of such patterns to little-studied portions of the Pumpkin Valley Shale. Such knowledge better allows for the satisfactory operation and assessment of the hydraulic fracturing at Oak Ridge National Laboratory

Geological and petrological considerations relevant to the disposal of radioactive wastes by hydraulic fracturing: an example at the US Department of Energy's Oak Ridge National Laboratory

International Nuclear Information System (INIS)

Haase, C.S.

1983-01-01

At Oak Ridge National Laboratory the Pumpkin Valley Shale is used as a host formation for hydraulic fracturing waste disposal. Determination of the relationships between the distribution of different lithologies and porosity-permeability trends within this host formation allows these properties, important to hydraulic fracturing operations, to be related to measurable and mappable geological and petrological parameters. It also permits extrapolation of such patterns to little-studied portions of the Pumpkin Valley Shale. Such knowledge better allows for the satisfactory operation and assessment of the hydraulic fracturing at Oak Ridge National Laboratory
An Efficient Upscaling Procedure Based on Stokes-Brinkman Model and Discrete Fracture Network Method for Naturally Fractured Carbonate Karst Reservoirs

KAUST Repository

Qin, Guan

2010-01-01

Naturally-fractured carbonate karst reservoirs are characterized by various-sized solution caves that are connected via fracture networks at multiple scales. These complex geologic features can not be fully resolved in reservoir simulations due to the underlying uncertainty in geologic models and the large computational resource requirement. They also bring in multiple flow physics which adds to the modeling difficulties. It is thus necessary to develop a method to accurately represent the effect of caves, fractures and their interconnectivities in coarse-scale simulation models. In this paper, we present a procedure based on our previously proposed Stokes-Brinkman model (SPE 125593) and the discrete fracture network method for accurate and efficient upscaling of naturally fractured carbonate karst reservoirs.
A study on site characterization of the deep geological environment around KURT

International Nuclear Information System (INIS)

Park, Kw; Kim, Gy; Koh, Yk; Kim, Ks; Choi, Jw

2009-01-01

KURT (KAERI Underground Research Tunnel) is a small scale research tunnel which was constructed from 2005 to 2006 at Korea Atomic Energy Research Institute (KAERI). To understand the deep geological environment around KURT area, the surface geological surveys such as lineaments analysis and geophysical survey and borehole investigation were performed. For this study, a 3 dimensional geological model has been constructed using the surface and borehole geological data. The regional lineaments were determined using a topographical map and the surface geophysical survey data were collected for the geological model. In addition, statistical methods were applied to fracture data from borehole televiewer loggings to identify fracture zones in boreholes. For a hydro geological modeling, fixed interval hydraulic tests were carried out for all boreholes. The results of the hydraulic tests were analyzed and classified by the fracture zone data of geological model. At result, the hydrogeological elements were decided and the properties of each element were assessed around the KURT area
Flow characteristics through a single fracture of artificial fracture system

International Nuclear Information System (INIS)

Park, Byoung Yoon; Bae, Dae Seok; Kim, Chun Soo; Kim, Kyung Su; Koh, Young Kwon; Jeon, Seok Won

2001-04-01

Fracture flow in rock masses is one of the most important issues in petroleum engineering, geology, and hydrogeology. Especially, in case of the HLW disposal, groundwater flow in fractures is an important factor in the performance assessment of the repository because the radionuclides move along the flowing groundwater through fractures. Recently, the characterization of fractures and the modeling of fluid flow in fractures are studied by a great number of researchers. Among those studies, the hydraulic behavior in a single fracture is one of the basic issues for understanding of fracture flow in rockmass. In this study, a fluid flow test in the single fracture made of transparent epoxy replica was carried out to obtain the practical exponent values proposed from the Cubic law and to estimate the flow rates through a single fracture. Not only the relationship between flow rates and the geometry of fracture was studied, but also the various statistical parameters of fracture geometry were compared to the effective transmissivity data obtained from computer simulation.
Effects of fracture distribution and length scale on the equivalent continuum elastic compliance of fractured rock masses

Directory of Open Access Journals (Sweden)

Marte Gutierrez

2015-12-01

Full Text Available Fracture systems have strong influence on the overall mechanical behavior of fractured rock masses due to their relatively lower stiffness and shear strength than those of the rock matrix. Understanding the effects of fracture geometrical distribution, such as length, spacing, persistence and orientation, is important for quantifying the mechanical behavior of fractured rock masses. The relation between fracture geometry and the mechanical characteristics of the fractured rock mass is complicated due to the fact that the fracture geometry and mechanical behaviors of fractured rock mass are strongly dependent on the length scale. In this paper, a comprehensive study was conducted to determine the effects of fracture distribution on the equivalent continuum elastic compliance of fractured rock masses over a wide range of fracture lengths. To account for the stochastic nature of fracture distributions, three different simulation techniques involving Oda's elastic compliance tensor, Monte Carlo simulation (MCS, and suitable probability density functions (PDFs were employed to represent the elastic compliance of fractured rock masses. To yield geologically realistic results, parameters for defining fracture distributions were obtained from different geological fields. The influence of the key fracture parameters and their relations to the overall elastic behavior of the fractured rock mass were studied and discussed. A detailed study was also carried out to investigate the validity of the use of a representative element volume (REV in the equivalent continuum representation of fractured rock masses. A criterion was also proposed to determine the appropriate REV given the fracture distribution of the rock mass.
Geology Laxemar. Site descriptive modelling SDM-Site Laxemar

Energy Technology Data Exchange (ETDEWEB)

Wahlgren, Carl-Henric (Geological Survey of Sweden, Uppsala (Sweden)); Curtis, Philip; Hermanson, Jan; Forssberg, Ola; Oehman, Johan (Golder Associates AB (Sweden)); Fox, Aaron; La Pointe, Paul (Golder Associates Inc (United States)); Drake, Henrik (Dept. of Earth Sciences, Univ. of Goeteborg, Goeteborg (Sweden)); Triumf, Carl-Axel; Mattsson, Haakan; Thunehed, Hans (GeoVista AB, Luleaa (Sweden)); Juhlin, Christopher (Dept. of Earth Sciences, Uppsala Univ., Uppsala (Sweden))

2008-11-15

The geological work during the SDM Site Laxemar modelling stage has involved the continued development of deterministic models for rock domains (RSM) and deformation zones (ZSM), the identification and deterministic modelling of fracture domains (FSM), and the development of statistical models for fractures and minor deformation zones (geological discrete fracture network (DFN) modelling). The geological DFN model addresses fractures/structures with a size of less than 1 km, which is the lower cut-off of structures included in the deterministic modelling of deformation zones. In order to take account of variability in data resolution, deterministic models for rock domains and deformation zones are presented in both regional and local scale model volumes, while the geological DFN model is valid only within specific fracture domains inside the Laxemar local model volume. The geological and geophysical data that constitute the basis for the SDM-Site Laxemar modelling work comprise all data that have been acquired from Laxemar, i.e. all data that were available at the data freeze for SDM-Site Laxemar at August 31, 2007. Selected quality controlled data from the complementary cored borehole KLX27A have also been utilised in the modelling work. Data from the following investigations were acquired during the complete site investigation between the data freezes for Laxemar 1.2 and SDM-Site Laxemar as defined above: A revised bedrock geological map at the ground surface. Geological and geophysical data from 40 new cored boreholes and 14 percussion boreholes. Sampling and subsequent modal and geochemical analytical work of bedrock samples taken in connection with excavations in southern Laxemar. Detailed mapping of fractures and rock units along 10 trench excavations and 2 large surface exposures (drill sites for KLX09 and KLX11A/KLX20A). Special studies involving more detailed characterisation of deformation zones identified in the geological single-hole interpretation
Geology Laxemar. Site descriptive modelling SDM-Site Laxemar

International Nuclear Information System (INIS)

Wahlgren, Carl-Henric; Curtis, Philip; Hermanson, Jan; Forssberg, Ola; Oehman, Johan; Fox, Aaron; La Pointe, Paul; Drake, Henrik; Triumf, Carl-Axel; Mattsson, Haakan; Thunehed, Hans; Juhlin, Christopher

2008-11-01

The geological work during the SDM Site Laxemar modelling stage has involved the continued development of deterministic models for rock domains (RSM) and deformation zones (ZSM), the identification and deterministic modelling of fracture domains (FSM), and the development of statistical models for fractures and minor deformation zones (geological discrete fracture network (DFN) modelling). The geological DFN model addresses fractures/structures with a size of less than 1 km, which is the lower cut-off of structures included in the deterministic modelling of deformation zones. In order to take account of variability in data resolution, deterministic models for rock domains and deformation zones are presented in both regional and local scale model volumes, while the geological DFN model is valid only within specific fracture domains inside the Laxemar local model volume. The geological and geophysical data that constitute the basis for the SDM-Site Laxemar modelling work comprise all data that have been acquired from Laxemar, i.e. all data that were available at the data freeze for SDM-Site Laxemar at August 31, 2007. Selected quality controlled data from the complementary cored borehole KLX27A have also been utilised in the modelling work. Data from the following investigations were acquired during the complete site investigation between the data freezes for Laxemar 1.2 and SDM-Site Laxemar as defined above: A revised bedrock geological map at the ground surface. Geological and geophysical data from 40 new cored boreholes and 14 percussion boreholes. Sampling and subsequent modal and geochemical analytical work of bedrock samples taken in connection with excavations in southern Laxemar. Detailed mapping of fractures and rock units along 10 trench excavations and 2 large surface exposures (drill sites for KLX09 and KLX11A/KLX20A). Special studies involving more detailed characterisation of deformation zones identified in the geological single-hole interpretation
Effects of simplifying fracture network representation on inert chemical migration in fracture-controlled aquifers

Science.gov (United States)

Wellman, Tristan; Shapiro, Allen M.; Hill, Mary C.

2009-01-01

While it is widely recognized that highly permeable 'large-scale' fractures dominate chemical migration in many fractured aquifers, recent studies suggest that the pervasive 'small-scale' fracturing once considered of less significance can be equally important for characterizing the spatial extent and residence time associated with transport processes. A detailed examination of chemical migration through fracture-controlled aquifers is used to advance this conceptual understanding. The influence of fracture structure is evaluated by quantifying the effects to transport caused by a systematic removal of fractures from three-dimensional discrete fracture models whose attributes are derived from geologic and hydrologic conditions at multiple field sites. Results indicate that the effects to transport caused by network simplification are sensitive to the fracture network characteristics, degree of network simplification, and plume travel distance, but primarily in an indirect sense since correlation to individual attributes is limited. Transport processes can be 'enhanced' or 'restricted' from network simplification meaning that the elimination of fractures may increase or decrease mass migration, mean travel time, dispersion, and tailing of the concentration plume. The results demonstrate why, for instance, chemical migration may not follow the classic advection-dispersion equation where dispersion approximates the effect of the ignored geologic structure as a strictly additive process to the mean flow. The analyses further reveal that the prediction error caused by fracture network simplification is reduced by at least 50% using the median estimate from an ensemble of simplified fracture network models, and that the error from network simplification is at least 70% less than the stochastic variability from multiple realizations. Copyright 2009 by the American Geophysical Union.
On-line Optimization-Based Simulators for Fractured and Non-fractured Reservoirs

Energy Technology Data Exchange (ETDEWEB)

Milind D. Deo

2005-08-31

Oil field development is a multi-million dollar business. Reservoir simulation is often used to guide the field management and development process. Reservoir characterization and geologic modeling tools have become increasingly sophisticated. As a result the geologic models produced are complex. Most reservoirs are fractured to a certain extent. The new geologic characterization methods are making it possible to map features such as faults and fractures, field-wide. Significant progress has been made in being able to predict properties of the faults and of the fractured zones. Traditionally, finite difference methods have been employed in discretizing the domains created by geologic means. For complex geometries, finite-element methods of discretization may be more suitable. Since reservoir simulation is a mature science, some of the advances in numerical methods (linear, nonlinear solvers and parallel computing) have not been fully realized in the implementation of most of the simulators. The purpose of this project was to address some of these issues. {sm_bullet} One of the goals of this project was to develop a series of finite-element simulators to handle problems of complex geometry, including systems containing faults and fractures. {sm_bullet} The idea was to incorporate the most modern computing tools; use of modular object-oriented computer languages, the most sophisticated linear and nonlinear solvers, parallel computing methods and good visualization tools. {sm_bullet} One of the tasks of the project was also to demonstrate the construction of fractures and faults in a reservoir using the available data and to assign properties to these features. {sm_bullet} Once the reservoir model is in place, it is desirable to find the operating conditions, which would provide the best reservoir performance. This can be accomplished by utilization optimization tools and coupling them with reservoir simulation. Optimization-based reservoir simulation was one of the
3D Geological Model for "LUSI" - a Deep Geothermal System

Science.gov (United States)

Sohrabi, Reza; Jansen, Gunnar; Mazzini, Adriano; Galvan, Boris; Miller, Stephen A.

2016-04-01

Geothermal applications require the correct simulation of flow and heat transport processes in porous media, and many of these media, like deep volcanic hydrothermal systems, host a certain degree of fracturing. This work aims to understand the heat and fluid transport within a new-born sedimentary hosted geothermal system, termed Lusi, that began erupting in 2006 in East Java, Indonesia. Our goal is to develop conceptual and numerical models capable of simulating multiphase flow within large-scale fractured reservoirs such as the Lusi region, with fractures of arbitrary size, orientation and shape. Additionally, these models can also address a number of other applications, including Enhanced Geothermal Systems (EGS), CO2 sequestration (Carbon Capture and Storage CCS), and nuclear waste isolation. Fractured systems are ubiquitous, with a wide-range of lengths and scales, making difficult the development of a general model that can easily handle this complexity. We are developing a flexible continuum approach with an efficient, accurate numerical simulator based on an appropriate 3D geological model representing the structure of the deep geothermal reservoir. Using previous studies, borehole information and seismic data obtained in the framework of the Lusi Lab project (ERC grant n°308126), we present here the first 3D geological model of Lusi. This model is calculated using implicit 3D potential field or multi-potential fields, depending on the geological context and complexity. This method is based on geological pile containing the geological history of the area and relationship between geological bodies allowing automatic computation of intersections and volume reconstruction. Based on the 3D geological model, we developed a new mesh algorithm to create hexahedral octree meshes to transfer the structural geological information for 3D numerical simulations to quantify Thermal-Hydraulic-Mechanical-Chemical (THMC) physical processes.
Research on fracture analysis, groundwater flow and sorption processes in fractured rocks

Energy Technology Data Exchange (ETDEWEB)

Lee, Dae Ha [Korea Institute of Geology Mining and Materials, Taejon (Korea)

1998-12-01

Due to increasing demand for numerous industrial facilities including nuclear power plants and waste repositories, the feasibility of rocks masses as sites for the facilities has been a geological issue of concern. Rock masses, in general, comprises systems of fractures which can provide pathways for groundwater flow and may also affect the stability of engineered structures. such properties of fractures stimulate a synthetic study on (1) analyses of fracture systems, and (2) characterization of groundwater flow and sorption processes in fractured rocks to establish a preliminary model for assessing suitable sites for industrial facilities. The analyses of fracture systems cover (1) reconstruction of the Cenozoic tectonic movements and estimation of frequency indices for the Holocene tectonic movements, (2) determination of distributions and block movements of the Quaternary marine terraces, (3) investigation of lithologic and geotechnical nature of study area, and (4) examination of the Cenozoic volcanic activities and determination of age of the dike swarms. Using data obtained from above mentioned analyses along with data related to earthquakes and active faults, probabilistic approach is performed to determine various potential hazards which may result from the Quaternary or the Holocene tectonic movements. In addition, stepwise and careful integration of various data obtained from field works and laboratory experiments are carried out to analyze groundwater flow in fractures rocks as follows; (1) investigation of geological feature of the site, (2) identification and characterization of fracture systems using core and televiewer logs, (3) determination of conductive fractures using electrical conductivity, temperature, and flow logs, (4) identification of hydraulic connections between fractures using televiewer logs with tracer tests within specific zones. The results obtained from these processes allow a qualitative interpretation of groundwater flow patterns
Anomalous Transport in Natural Fracture Networks Induced by Tectonic Stress

Science.gov (United States)

Kang, P. K.; Lei, Q.; Lee, S.; Dentz, M.; Juanes, R.

2017-12-01

Fluid flow and transport in fractured rock controls many natural and engineered processes in the subsurface. However, characterizing flow and transport through fractured media is challenging due to the high uncertainty and large heterogeneity associated with fractured rock properties. In addition to these "static" challenges, geologic fractures are always under significant overburden stress, and changes in the stress state can lead to changes in the fracture's ability to conduct fluids. While confining stress has been shown to impact fluid flow through fractures in a fundamental way, the impact of confining stress on transportthrough fractured rock remains poorly understood. The link between anomalous (non-Fickian) transport and confining stress has been shown, only recently, at the level of a single rough fracture [1]. Here, we investigate the impact of geologic (tectonic) stress on flow and tracer transport through natural fracture networks. We model geomechanical effects in 2D fractured rock by means of a finite-discrete element method (FEMDEM) [2], which can capture the deformation of matrix blocks, reactivation of pre-existing fractures, and propagation of new cracks, upon changes in the stress field. We apply the model to a fracture network extracted from the geological map of an actual rock outcrop to obtain the aperture field at different stress conditions. We then simulate fluid flow and particle transport through the stressed fracture networks. We observe that anomalous transport emerges in response to confining stress on the fracture network, and show that the stress state is a powerful determinant of transport behavior: (1) An anisotropic stress state induces preferential flow paths through shear dilation; (2) An increase in geologic stress increases aperture heterogeneity that induces late-time tailing of particle breakthrough curves. Finally, we develop an effective transport model that captures the anomalous transport through the stressed fracture
Geological Structures Mapping of Bukit Bunuh using 2-D Resistivity Imaging Method

Science.gov (United States)

Nur Amalina, M. K. A.; Nordiana, M. M.; Rahman, Nazrin; Saidin, Mokhtar; Masnan, S. S. K.

2018-04-01

The geological area of Bukit Bunuh is very complex due to the meteorite impact that has occurred millions years ago at Lenggong, Perak. The lithology of the study area consists of alluvium, tephra dust, and granitic rock. The geological contact, fault and fracture zone were found at the study area may indicate the geological process that undergoes at a place locally or regionally. These important features have led to the further research on 2-D resistivity imaging method (2-D RIM) to study the geological features. This method can provide the subsurface image that will delineate the geological structures. The surveys include three separate lines of different length which depend on the accessibility. The surveys were done by using Pole-Dipole array and 10 m of electrodes spacing. The objectives of this research are to determine the subsurface geological contact and to determine the existence of fault/fracture zones at the contact zone. The results from 2-D inversion profiles have successfully signified the types of geological structural such as fault, contact, and fractures. Hence, the results from 2-D RIM were used to draw the geological lineaments of Bukit Bunuh. The discontinuity of the lineaments may indicate the structures present.
Connection between tectonic stresses and well fracturing data

Energy Technology Data Exchange (ETDEWEB)

Scheidegger, A E [Imperial Oil Res. Lab., Calgary, CA

1961-01-01

Theoretical considerations of hydraulic well fracturing normally utilize a model in which the borehole is assumed to be a cylinder of infinite length. This leads to treatment of the induced stress state in two dimensions. The two-dimensional model is obviously an oversimplification. Therefore, a three-dimensional model is proposed in which the well pressure is assumed to be equivalent to a spherical pressure center. The bottom hole pressure during fracturing is determined by 4 variables; i.e., the 3 principal geological stresses and the rock strength. The response to fracturing is determined primarily by the prevailing stress state and to a lesser degree by the rock strength. The fracture condition is formulated and the model is used in the calculation of geological stresses from well data.
Geosciences research: development of techniques and instruments for investigation geological environments

International Nuclear Information System (INIS)

1993-01-01

In order to understand the geological environment in Japan, new investigation techniques have been developed. These include: 1) Geological techniques for fracture characterization, 2) Nondestructive investigation techniques for detailed geological structure, 3) Instruments for hydraulic characterization, 4) Instruments for hydrochemical characterization. Results so far obtained are: 1) Fractures can be classified by their patterns, 2) The applicability and limitations of conventional geophysical methods were defined, 3) Instruments for measuring very low permeability were successfully developed, 4) Instruments for sampling formation water without changing in-situ conditions were developed. (author)
Synthetic Study on the Geological and Hydrogeological Model around KURT

International Nuclear Information System (INIS)

Park, Kyung Woo; Kim, Kyung Su; Koh, Yong Kwon; Choi, Jong Won

2011-01-01

To characterize the site specific properties of a study area for high-level radioactive waste disposal research in KAERI, the several geological investigations such as surface geological surveys and borehole drillings were carried out since 1997. Especially, KURT (KAERI Underground Research Tunnel) was constructed to understand the further study of geological environments in 2006. As a result, the first geological model of a study area was constructed by using the results of geological investigation. The objective of this research is to construct a hydrogeological model around KURT area on the basis of the geological model. Hydrogeological data which were obtained from in-situ hydraulic tests in the 9 boreholes were estimated to accomplish the objective. And, the hydrogeological properties of the 4 geological elements in the geological model, which were the subsurface weathering zone, the log angle fracture zone, the fracture zones and the bedrock were suggested. The hydrogeological model suggested in this study will be used as input parameters to carry out the groundwater flow modeling as a next step of the site characterization around KURT area
Fractured reservoir discrete feature network technologies. Annual report, March 7, 1996--February 28, 1997

Energy Technology Data Exchange (ETDEWEB)

Dershowitz, W.S.; La Pointe, P.R.; Einstein, H.H.; Ivanova, V.

1998-01-01

This report describes progress on the project, {open_quotes}Fractured Reservoir Discrete Feature Network Technologies{close_quotes} during the period March 7, 1996 to February 28, 1997. The report presents summaries of technology development for the following research areas: (1) development of hierarchical fracture models, (2) fractured reservoir compartmentalization and tributary volume, (3) fractured reservoir data analysis, and (4) integration of fractured reservoir data and production technologies. In addition, the report provides information on project status, publications submitted, data collection activities, and technology transfer through the world wide web (WWW). Research on hierarchical fracture models included geological, mathematical, and computer code development. The project built a foundation of quantitative, geological and geometrical information about the regional geology of the Permian Basin, including detailed information on the lithology, stratigraphy, and fracturing of Permian rocks in the project study area (Tracts 17 and 49 in the Yates field). Based on the accumulated knowledge of regional and local geology, project team members started the interpretation of fracture genesis mechanisms and the conceptual modeling of the fracture system in the study area. Research on fractured reservoir compartmentalization included basic research, technology development, and application of compartmentalized reservoir analyses for the project study site. Procedures were developed to analyze compartmentalization, tributary drainage volume, and reservoir matrix block size. These algorithms were implemented as a Windows 95 compartmentalization code, FraCluster.
Training and Research on Probabilistic Hydro-Thermo-Mechanical Modeling of Carbon Dioxide Geological Sequestration in Fractured Porous Rocks

Energy Technology Data Exchange (ETDEWEB)

Gutierrez, Marte

2013-05-31

Colorado School of Mines conducted research and training in the development and validation of an advanced CO{sub 2} GS (Geological Sequestration) probabilistic simulation and risk assessment model. CO{sub 2} GS simulation and risk assessment is used to develop advanced numerical simulation models of the subsurface to forecast CO2 behavior and transport; optimize site operational practices; ensure site safety; and refine site monitoring, verification, and accounting efforts. As simulation models are refined with new data, the uncertainty surrounding the identified risks decrease, thereby providing more accurate risk assessment. The models considered the full coupling of multiple physical processes (geomechanical and fluid flow) and describe the effects of stochastic hydro-mechanical (H-M) parameters on the modeling of CO{sub 2} flow and transport in fractured porous rocks. Graduate students were involved in the development and validation of the model that can be used to predict the fate, movement, and storage of CO{sub 2} in subsurface formations, and to evaluate the risk of potential leakage to the atmosphere and underground aquifers. The main major contributions from the project include the development of: 1) an improved procedure to rigorously couple the simulations of hydro-thermomechanical (H-M) processes involved in CO{sub 2} GS; 2) models for the hydro-mechanical behavior of fractured porous rocks with random fracture patterns; and 3) probabilistic methods to account for the effects of stochastic fluid flow and geomechanical properties on flow, transport, storage and leakage associated with CO{sub 2} GS. The research project provided the means to educate and train graduate students in the science and technology of CO{sub 2} GS, with a focus on geologic storage. Specifically, the training included the investigation of an advanced CO{sub 2} GS simulation and risk assessment model that can be used to predict the fate, movement, and storage of CO{sub 2} in
Use of Geological Lineaments Results in Groundwater Exploration ...

African Journals Online (AJOL)

Locating aquifiers in Precambrian crystalline rocks offers major problems unless areas of intense weathering or fracturing are targeted. These normally occur along geological lineaments which can be identified during groundwater exploration. Major geological lineaments were identified in the Zomba area, southern Malawi ...
Fractures and Rock Mechanics, Phase 1

DEFF Research Database (Denmark)

Krogsbøll, Anette; Jakobsen, Finn; Madsen, Lena

1997-01-01

The main objective of the project is to combine geological descriptions of fractures, chalk types and rock mechanical properties in order to investigate whether the chosen outcrops can be used as analogues to reservoir chalks. This report deals with 1) geological descriptions of outcrop locality...

Surface analogue outcrops of deep fractured basement reservoirs in extensional geological settings. Examples within active rift system (Uganda) and proximal passive margin (Morocco).

Science.gov (United States)

Walter, Bastien; Géraud, Yves; Diraison, Marc

2014-05-01

The important role of extensive brittle faults and related structures in the development of reservoirs has already been demonstrated, notably in initially low-porosity rocks such as basement rocks. Large varieties of deep-seated resources (e.g. water, hydrocarbons, geothermal energy) are recognized in fractured basement reservoirs. Brittle faults and fracture networks can develop sufficient volumes to allow storage and transfer of large amounts of fluids. Development of hydraulic model with dual-porosity implies the structural and petrophysical characterization of the basement. Drain porosity is located within the larger fault zones, which are the main fluid transfer channels. The storage porosity corresponds both to the matrix porosity and to the volume produced by the different fractures networks (e.g. tectonic, primary), which affect the whole reservoir rocks. Multi-scale genetic and geometric relationships between these deformation features support different orders of structural domains in a reservoir, from several tens of kilometers to few tens of meters. In subsurface, 3D seismic data in basement can be sufficient to characterize the largest first order of structural domains and bounding fault zones (thickness, main orientation, internal architecture, …). However, lower order structural blocks and fracture networks are harder to define. The only available data are 1D borehole electric imaging and are used to characterize the lowest order. Analog outcrop studies of basement rocks fill up this resolution gap and help the understanding of brittle deformation, definition of reservoir geometries and acquirement of reservoir properties. These geological outcrop studies give information about structural blocks of second and third order, getting close to the field scale. This allows to understand relationships between brittle structures geometry and factors controlling their development, such as the structural inheritance or the lithology (e.g. schistosity, primary
Geology of the host formation for the new hydraulic fracturing facility at Oak Ridge National Laboratory

International Nuclear Information System (INIS)

Haase, C.S.; Stow, S.H.; Zucker, C.L.; University of Tennessee, Knoxville)

1985-01-01

Liquid low-level radioactive wastes are disposed of at Oak Ridge National Laboratory (ORNL) by the hydrofracture process. Wastes are mixed with cement and other additives to form a slurry that is injected into a low permeability shale at 300-m depth. Important properties for a host shale formation at a hydrofracture facility include: (1) predictable fracture behavior; (2) hydrologic isolation; and (3) favorable mineralogy and geochemistry to retard radionuclide migration and enhance grout stability. The stratigraphy, petrology, diagenesis, structural geology, and hydrology of the Pumpkin Valley Shale host formation at the ORNL site are summarized and discussed in light of these three properties. Empirical data from hydrofracture operations at ORNL over the past 25 years suggest that many aspects of the Pumpkin Valley Shale make it favorable for use as a host. This observation agrees with analysis of several aspects of the Pumpkin Valley Shale geology at the ORNL site. Although presently available data suggest that the permeability of the Pumpkin Valley Shale is low and that it should provide sufficient hydrologic isolation, more data are needed to properly evaluate this aspect of host formation performance
Shear-induced Fracture Slip and Permeability Change. Implications for Long-term Performance of a Deep Geological Repository

International Nuclear Information System (INIS)

Min, Ki-Bok; Stephansson, Ove

2009-03-01

Opening of fractures induced by shear dilation or normal deformation can be a significant source of fracture permeability change in jointed rock, which is important for the performance assessment of geological repositories for spent nuclear fuel. As the repository generates heat and later cools the fluid-carrying ability of the rocks becomes a dynamic variable during the lifespan of the repository. Heating causes expansion of the rock close to the repository and, at the same time, contraction close to the surface. During the cooling phase of the repository, the opposite takes place. Heating and cooling together with the virgin stress can induce shear dilation of fractures and deformation zones and change the flow field around the repository. The objectives of this project are to examine the contribution of thermal stress to the shear slip of fracture in mid- and far-field around a KBS-3 type of repository and to investigate the effect of evolution of stress on the rock mass permeability. The first part of the study is about the evolution of thermal stresses in the rock during the lifetime of the repository. Critical sections of heat generated stresses around the repository are selected and classified. Fracture data from Forsmark is used to establish fracture network models (DFN) and the models are subjected to the sum of virgin stress and thermal stresses and the shear slip and related permeability change are studied. In the first part of this study, zones of fracture shear slip were examined by conducting a three-dimensional, thermo-mechanical analysis of a spent fuel repository model. Stress evolutions of importance for fracture shear slip are: (1) comparatively high horizontal compressive thermal stress at the repository level, (2) generation of vertical tensile thermal stress right above the repository, (3) horizontal tensile stress near the surface, which can induce tensile failure, and generation of shear stresses at the corners of the repository. In the
Shear-induced Fracture Slip and Permeability Change. Implications for Long-term Performance of a Deep Geological Repository

Energy Technology Data Exchange (ETDEWEB)

Min, Ki-Bok (School of Civil, Environmental and Mining Engineering, Univ. of Adelaide, Adelaide (Australia)); Stephansson, Ove (Steph Rock Consulting AB, Berlin (Germany))

2009-03-15

Opening of fractures induced by shear dilation or normal deformation can be a significant source of fracture permeability change in jointed rock, which is important for the performance assessment of geological repositories for spent nuclear fuel. As the repository generates heat and later cools the fluid-carrying ability of the rocks becomes a dynamic variable during the lifespan of the repository. Heating causes expansion of the rock close to the repository and, at the same time, contraction close to the surface. During the cooling phase of the repository, the opposite takes place. Heating and cooling together with the virgin stress can induce shear dilation of fractures and deformation zones and change the flow field around the repository. The objectives of this project are to examine the contribution of thermal stress to the shear slip of fracture in mid- and far-field around a KBS-3 type of repository and to investigate the effect of evolution of stress on the rock mass permeability. The first part of the study is about the evolution of thermal stresses in the rock during the lifetime of the repository. Critical sections of heat generated stresses around the repository are selected and classified. Fracture data from Forsmark is used to establish fracture network models (DFN) and the models are subjected to the sum of virgin stress and thermal stresses and the shear slip and related permeability change are studied. In the first part of this study, zones of fracture shear slip were examined by conducting a three-dimensional, thermo-mechanical analysis of a spent fuel repository model. Stress evolutions of importance for fracture shear slip are: (1) comparatively high horizontal compressive thermal stress at the repository level, (2) generation of vertical tensile thermal stress right above the repository, (3) horizontal tensile stress near the surface, which can induce tensile failure, and generation of shear stresses at the corners of the repository. In the
Bedrock geology Forsmark. Modelling stage 2.3. Implications for and verification of the deterministic geological models based on complementary data

Energy Technology Data Exchange (ETDEWEB)

Stephens, Michael B. (Geological Survey of Sweden, Uppsala (Sweden)); Simeonov, Assen (Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)); Isaksson, Hans (GeoVista AB, Luleaa (Sweden))

2008-12-15

The Swedish Nuclear Fuel and Waste Management Company is in the process of completing site descriptive modelling at two locations in Sweden, with the objective to site a deep geological repository for spent nuclear fuel. At Forsmark, the results of the stage 2.2 geological modelling formed the input for downstream users. Since complementary ground and borehole geological and geophysical data, acquired after model stage 2.2, were not planned to be included in the deterministic rock domain, fracture domain and deformation zone models supplied to the users, it was deemed necessary to evaluate the implications of these stage 2.3 data for the stage 2.2 deterministic geological models and, if possible, to make use of these data to verify the models. This report presents the results of the analysis of the complementary stage 2.3 geological and geophysical data. Model verification from borehole data has been implemented in the form of a prediction-outcome test. The stage 2.3 geological and geophysical data at Forsmark mostly provide information on the bedrock outside the target volume. Additional high-resolution ground magnetic data and the data from the boreholes KFM02B, KFM11A, KFM12A and HFM33 to HFM37 can be included in this category. Other data complement older information of identical character, both inside and outside this volume. These include the character and kinematics of deformation zones and fracture mineralogy. In general terms, it can be stated that all these new data either confirm the geological modelling work completed during stage 2.2 or are in good agreement with the data that were used in this work. In particular, although the new high-resolution ground magnetic data modify slightly the position and trace length of some stage 2.2 deformation zones at the ground surface, no new or modified deformation zones with a trace length longer than 3,000 m at the ground surface have emerged. It is also apparent that the revision of fracture orientation data
Bedrock geology Forsmark. Modelling stage 2.3. Implications for and verification of the deterministic geological models based on complementary data

International Nuclear Information System (INIS)

Stephens, Michael B.; Simeonov, Assen; Isaksson, Hans

2008-12-01

The Swedish Nuclear Fuel and Waste Management Company is in the process of completing site descriptive modelling at two locations in Sweden, with the objective to site a deep geological repository for spent nuclear fuel. At Forsmark, the results of the stage 2.2 geological modelling formed the input for downstream users. Since complementary ground and borehole geological and geophysical data, acquired after model stage 2.2, were not planned to be included in the deterministic rock domain, fracture domain and deformation zone models supplied to the users, it was deemed necessary to evaluate the implications of these stage 2.3 data for the stage 2.2 deterministic geological models and, if possible, to make use of these data to verify the models. This report presents the results of the analysis of the complementary stage 2.3 geological and geophysical data. Model verification from borehole data has been implemented in the form of a prediction-outcome test. The stage 2.3 geological and geophysical data at Forsmark mostly provide information on the bedrock outside the target volume. Additional high-resolution ground magnetic data and the data from the boreholes KFM02B, KFM11A, KFM12A and HFM33 to HFM37 can be included in this category. Other data complement older information of identical character, both inside and outside this volume. These include the character and kinematics of deformation zones and fracture mineralogy. In general terms, it can be stated that all these new data either confirm the geological modelling work completed during stage 2.2 or are in good agreement with the data that were used in this work. In particular, although the new high-resolution ground magnetic data modify slightly the position and trace length of some stage 2.2 deformation zones at the ground surface, no new or modified deformation zones with a trace length longer than 3,000 m at the ground surface have emerged. It is also apparent that the revision of fracture orientation data
Geology and fracture system at Stripa. Technical information report No. 21

International Nuclear Information System (INIS)

Olkiewicz, A.; Gale, J.E.; Thorpe, R.; Paulsson, B.

1979-02-01

The Stripa test site has been excavated in granitic rock between 338 m and 360 m below the ground surface, and is located under the north limb of an ENE-plunging synclinal structure. The granitic rocks, in the areas mapped, are of Archean age and are dominated by a reddish, medium-grained, massive monzogranite that shows varying degrees of deformation. The granitic rocks have been intruded by diabase (dolerite) and pegmatite dikes. Surface and subsurface mapping shows that the Stripa granite is highly fractured and that there are at least four joint sets in the area of the test excavations. In addition to the joints, the rock mass contains fissures, fracture zones, and small-scale shear zones, representing the complete spectrum of the fracture family. Most of the fractures are lined with chlorite, occasionally with calcite. Many of the small-scale shear fractures are filled or coated with epidote. Offsets of pegmatite dikes formed by these fractures are usually limited to one to two meters. Water seepage is observed only as drops from fractures or moist fracture surfaces. It was found that reconstruction of the local three-dimensional fracture system is the heater-experiment sites was difficult, and in some cases subjective. Such reconstruction is a prerequisite to accurate interpretation of thermal and mechanical data from such sites
Role of geomechanically grown fractures on dispersive transport in heterogeneous geological formations

KAUST Repository

Nick, H. M.

2011-11-04

A second order in space accurate implicit scheme for time-dependent advection-dispersion equations and a discrete fracture propagation model are employed to model solute transport in porous media. We study the impact of the fractures on mass transport and dispersion. To model flow and transport, pressure and transport equations are integrated using a finite-element, node-centered finite-volume approach. Fracture geometries are incrementally developed from a random distributions of material flaws using an adoptive geomechanical finite-element model that also produces fracture aperture distributions. This quasistatic propagation assumes a linear elastic rock matrix, and crack propagation is governed by a subcritical crack growth failure criterion. Fracture propagation, intersection, and closure are handled geometrically. The flow and transport simulations are separately conducted for a range of fracture densities that are generated by the geomechanical finite-element model. These computations show that the most influential parameters for solute transport in fractured porous media are as follows: fracture density and fracture-matrix flux ratio that is influenced by matrix permeability. Using an equivalent fracture aperture size, computed on the basis of equivalent permeability of the system, we also obtain an acceptable prediction of the macrodispersion of poorly interconnected fracture networks. The results hold for fractures at relatively low density. © 2011 American Physical Society.
Role of geomechanically grown fractures on dispersive transport in heterogeneous geological formations

KAUST Repository

Nick, H. M.; Paluszny, A.; Blunt, M. J.; Matthai, S. K.

2011-01-01

A second order in space accurate implicit scheme for time-dependent advection-dispersion equations and a discrete fracture propagation model are employed to model solute transport in porous media. We study the impact of the fractures on mass transport and dispersion. To model flow and transport, pressure and transport equations are integrated using a finite-element, node-centered finite-volume approach. Fracture geometries are incrementally developed from a random distributions of material flaws using an adoptive geomechanical finite-element model that also produces fracture aperture distributions. This quasistatic propagation assumes a linear elastic rock matrix, and crack propagation is governed by a subcritical crack growth failure criterion. Fracture propagation, intersection, and closure are handled geometrically. The flow and transport simulations are separately conducted for a range of fracture densities that are generated by the geomechanical finite-element model. These computations show that the most influential parameters for solute transport in fractured porous media are as follows: fracture density and fracture-matrix flux ratio that is influenced by matrix permeability. Using an equivalent fracture aperture size, computed on the basis of equivalent permeability of the system, we also obtain an acceptable prediction of the macrodispersion of poorly interconnected fracture networks. The results hold for fractures at relatively low density. © 2011 American Physical Society.
Process for structural geologic analysis of topography and point data

Science.gov (United States)

Eliason, Jay R.; Eliason, Valerie L. C.

1987-01-01

A quantitative method of geologic structural analysis of digital terrain data is described for implementation on a computer. Assuming selected valley segments are controlled by the underlying geologic structure, topographic lows in the terrain data, defining valley bottoms, are detected, filtered and accumulated into a series line segments defining contiguous valleys. The line segments are then vectorized to produce vector segments, defining valley segments, which may be indicative of the underlying geologic structure. Coplanar analysis is performed on vector segment pairs to determine which vectors produce planes which represent underlying geologic structure. Point data such as fracture phenomena which can be related to fracture planes in 3-dimensional space can be analyzed to define common plane orientation and locations. The vectors, points, and planes are displayed in various formats for interpretation.
Assessment of deep geological environment condition

International Nuclear Information System (INIS)

Bae, Dae Seok; Han, Kyung Won; Joen, Kwan Sik

2003-05-01

The main tasks of geoscientific study in the 2nd stage was characterized focusing mainly on a near-field condition of deep geologic environment, and aimed to generate the geologic input data for a Korean reference disposal system for high level radioactive wastes and to establish site characterization methodology, including neotectonic features, fracture systems and mechanical properties of plutonic rocks, and hydrogeochemical characteristics. The preliminary assessment of neotectonics in the Korean peninsula was performed on the basis of seismicity recorded, Quarternary faults investigated, uplift characteristics studied on limited areas, distribution of the major regional faults and their characteristics. The local fracture system was studied in detail from the data obtained from deep boreholes in granitic terrain. Through this deep drilling project, the geometrical and hydraulic properties of different fracture sets are statistically analysed on a block scale. The mechanical properties of intact rocks were evaluated from the core samples by laboratory testing and the in-situ stress conditions were estimated by a hydro fracturing test in the boreholes. The hydrogeochemical conditions in the deep boreholes were characterized based on hydrochemical composition and isotopic signatures and were attempted to assess the interrelation with a major fracture system. The residence time of deep groundwater was estimated by C-14 dating. For the travel time of groundwater between the boreholes, the methodology and equipment for tracer test were established
Optimizing Fracture Treatments in a Mississippian "Chat" Reservoir, South-Central Kansas

Energy Technology Data Exchange (ETDEWEB)

K. David Newell; Saibal Bhattacharya; Alan Byrnes; W. Lynn Watney; Willard Guy

2005-10-01

This project is a collaboration of Woolsey Petroleum Corporation (a small independent operator) and the Kansas Geological Survey. The project will investigate geologic and engineering factors critical for designing hydraulic fracture treatments in Mississippian ''chat'' reservoirs. Mississippian reservoirs, including the chat, account for 159 million m3 (1 billion barrels) of the cumulative oil produced in Kansas. Mississippian reservoirs presently represent {approx}40% of the state's 5.6*106m3 (35 million barrels) annual production. Although geographically widespread, the ''chat'' is a heterogeneous reservoir composed of chert, cherty dolomite, and argillaceous limestone. Fractured chert with micro-moldic porosity is the best reservoir in this 18- to 30-m-thick (60- to 100-ft) unit. The chat will be cored in an infill well in the Medicine Lodge North field (417,638 m3 [2,626,858 bbls] oil; 217,811,000 m3 [7,692,010 mcf] gas cumulative production; discovered 1954). The core and modern wireline logs will provide geological and petrophysical data for designing a fracture treatment. Optimum hydraulic fracturing design is poorly defined in the chat, with poor correlation of treatment size to production increase. To establish new geologic and petrophysical guidelines for these treatments, data from core petrophysics, wireline logs, and oil-field maps will be input to a fracture-treatment simulation program. Parameters will be established for optimal size of the treatment and geologic characteristics of the predicted fracturing. The fracturing will be performed and subsequent wellsite tests will ascertain the results for comparison to predictions. A reservoir simulation program will then predict the rate and volumetric increase in production. Comparison of the predicted increase in production with that of reality, and the hypothetical fracturing behavior of the reservoir with that of its actual behavior, will serve as tests of
Fracture mapping at the Spent Fuel Test-Climax

International Nuclear Information System (INIS)

Wilder, D.G.; Yow, J.L. Jr.

1981-05-01

Mapping of geologic discontinuities has been done in several phases at the Spent Fuel Test-Climax (SFT-C) in the granitic Climax stock at the Nevada Test Site. Mapping was carried out in the tail drift, access drift, canister drift, heater drifts, instrumentation alcove, and receiving room. The fractures mapped as intersecting a horizontal datum in the canister and heater drifts are shown on one figure. Fracture sketch maps have been compiled as additional figures. Geologic mapping efforts were scheduled around and significantly impacted by the excavation and construction schedules. Several people were involved in the mapping, and over 2500 geologic discontinuities were mapped, including joints, shears, and faults. Some variance between individuals' mapping efforts was noticed, and the effects of various magnetic influences upon a compass were examined. The examination of compass errors improved the credibility of the data. The compass analysis work is explained in Appendix A. Analysis of the fracture data will be presented in a future report
Lattice Boltzmann simulation of CO2 reactive transport in network fractured media

Science.gov (United States)

Tian, Zhiwei; Wang, Junye

2017-08-01

Carbon dioxide (CO2) geological sequestration plays an important role in mitigating CO2 emissions for climate change. Understanding interactions of the injected CO2 with network fractures and hydrocarbons is key for optimizing and controlling CO2 geological sequestration and evaluating its risks to ground water. However, there is a well-known, difficult process in simulating the dynamic interaction of fracture-matrix, such as dynamic change of matrix porosity, unsaturated processes in rock matrix, and effect of rock mineral properties. In this paper, we develop an explicit model of the fracture-matrix interactions using multilayer bounce-back treatment as a first attempt to simulate CO2 reactive transport in network fractured media through coupling the Dardis's LBM porous model for a new interface treatment. Two kinds of typical fracture networks in porous media are simulated: straight cross network fractures and interleaving network fractures. The reaction rate and porosity distribution are illustrated and well-matched patterns are found. The species concentration distribution and evolution with time steps are also analyzed and compared with different transport properties. The results demonstrate the capability of this model to investigate the complex processes of CO2 geological injection and reactive transport in network fractured media, such as dynamic change of matrix porosity.
Mapping Fractures in KAERI Underground Research Tunnel using Ground Penetrating Radar

Science.gov (United States)

Baek, Seung-Ho; Kim, Seung-Sep; Kwon, Jang-Soon

2016-04-01

The proportion of nuclear power in the Republic of Korea occupies about 40 percent of the entire electricity production. Processing or disposing nuclear wastes, however, remains one of biggest social issues. Although low- and intermediate-level nuclear wastes are stored temporarily inside nuclear power plants, these temporary storages can last only up to 2020. Among various proposed methods for nuclear waste disposal, a long-term storage using geologic disposal facilities appears to be most highly feasible. Geological disposal of nuclear wastes requires a nuclear waste repository situated deep within a stable geologic environment. However, the presence of small-scale fractures in bedrocks can cause serious damage to durability of such disposal facilities because fractures can become efficient pathways for underground waters and radioactive wastes. Thus, it is important to find and characterize multi-scale fractures in bedrocks hosting geologic disposal facilities. In this study, we aim to map small-scale fractures inside the KAERI Underground Research Tunnel (KURT) using ground penetrating radar (GPR). The KURT is situated in the Korea Atomic Energy Research Institute (KAERI). The survey target is a section of wall cut by a diamond grinder, which preserves diverse geologic features such as dykes. We conducted grid surveys on the wall using 500 MHz and 1000 MHz pulseEKKO PRO sensors. The observed GPR signals in both frequencies show strong reflections, which are consistent to form sloping planes. We interpret such planar features as fractures present in the wall. Such fractures were also mapped visually during the development of the KURT. We confirmed their continuity into the wall from the 3D GPR images. In addition, the spatial distribution and connectivity of these fractures are identified from 3D subsurface images. Thus, we can utilize GPR to detect multi-scale fractures in bedrocks, during and after developing underground disposal facilities. This study was
Research on fracture analysis, groundwater flow and sorption processes in fractured rocks

Energy Technology Data Exchange (ETDEWEB)

Lee, Dae-Ha; Kim, Won-Young; Lee, Seung-Gu [Korea Institute of Geology Mining and Materials, Taejon (KR)] (and others)

1999-12-01

Due to increasing demand for numerous industrial facilities including nuclear power plants and waste repositories, the feasibility of rocks masses as sites for the facilities has been a geological issue of concern. Rock masses, in general, comprises systems of fractures which can provide pathways for groundwater flow and may also affect the stability of engineered structures. For the study of groundwater flow and sorption processes in fractured rocks, five boreholes were drilled. A stepwise and careful integration of various data obtained from field works and laboratory experiments were carried out to analyze groundwater flow in fractured rocks as follows; (1) investigation of geological feature of the site, (2) identification and characterization of fracture systems using core and televiewer logs, (3) determination of hydrogeological properties of fractured aquifers using geophysical borehole logging, pumping and slug tests, and continuous monitoring of groundwater level and quality, (4) evaluation of groundwater flow patterns using fluid flow modeling. The results obtained from these processes allow a qualitative interpretation of fractured aquifers in the study area. Column experiments of some reactive radionuclides were also performed to examine sorption processes of the radionuclides including retardation coefficients. In addition, analyses of fracture systems covered (1) reconstruction of the Cenozoic tectonic movements and estimation of frequency indices for the Holocene tectonic movements, (2) determination of distributions and block movements of the Quaternary marine terraces, (3) investigation of lithologic and geotechnical nature of study area, and (4) examination of the Cenozoic volcanic activities and determination of age of the dike swarms. Using data obtained from above mentioned analyses along with data related to earthquakes and active faults, probabilistic approach was performed to determine various potential hazards which may result from the
Using outcrop data for geological well test modelling in fractured reservoirs

NARCIS (Netherlands)

Aljuboori, F.; Corbett, P.; Bisdom, K.; Bertotti, G.; Geiger, S.

2015-01-01

Outcrop fracture data sets can now be acquired with ever more accuracy using drone technology augmented by field observations. These models can be used to form realistic, deterministic models of fractured reservoirs. Fractured well test models are traditionally seen to be finite or infinite
The impact of episodic nonequilibrium fracture-matrix flow on geological repository performance

International Nuclear Information System (INIS)

Buscheck, T.A.; Nitao, J.J.; Chestnut, D.A.

1991-01-01

Adequate representation of fracture-matrix interaction during episodic infiltration events is crucial in making valid hydrological predictions of repository performance at Yucca Mountain. Various approximations have been applied to represent fracture-matrix flow interaction, including the Equivalent Continuum Model (ECM), which assumes capillary equilibrium between fractures and matrix, and the Fracture-Matrix Model (FMM), which accounts for nonequilibrium fracture-matrix flow. We analyze the relative impact of matrix imbibition on episodic nonequilibrium fracture-matrix flow for the eight major hydrostratigraphic units in the unsaturated zone at Yucca Mountain. Comparisons are made between ECM and FMM predictions to determine the applicability of the ECM. The implications of nonequilibrium fracture-matrix flow on radionuclide transport are also discussed
Canadian geologic isolation program

International Nuclear Information System (INIS)

Dyne, P.J.

1976-01-01

The Canadian geologic isolation program is directed at examining the potential of (1) salt deposits and (2) hard rock as repositories for radioactive wastes. It was felt essential from the inception that alternative host rocks be evaluated over a fairly large geographical area. The studies on salt deposits to date are based on existing geological information and have identified the areas that show some potential and merit further study. The factors considered include depth, thickness and purity of the deposit, overlying aquifers, and the potential for gas and oil exploration as well as potash recovery. The studies on hard rock are restricted to plutonic igneous rocks in the Ontario part of the Canadian Shield. Because geological information on their nature and extent is sparse, the study is limited to bodies that are well exposed and for which information is available.for which information is available. Field studies in the next two seasons are aimed at mapping the fault and joint patterns and defining the geologic controls on their development. In 1977 and 1978, two or three of the more favorable sites will be mapped in greater detail, and an exploratory drilling program will be established to determine the extent of fracturing at depth and the hydrology of these fractures. Conceptual designs of mined repositories in hard rock are also being made with the hope of identifying, at an early stage in this program, special problems in hard-rock repositories that may require development and study
Study on the Geological Structure around KURT Using a Deep Borehole Investigation

International Nuclear Information System (INIS)

Park, Kyung Woo; Kim, Kyung Su; Koh, Yong Kwon; Choi, Jong Won

2010-01-01

To characterize geological features in study area for high-level radioactive waste disposal research, KAERI (Korea Atomic Energy Research Institute) has been performing the several geological investigations such as geophysical surveys and borehole drilling since 1997. Especially, the KURT (KAERI Underground Research Tunnel) constructed to understand the deep geological environments in 2006. Recently, the deep borehole of 500 m depths was drilled to confirm and validate the geological model at the left research module of the KURT. The objective of this research was to identify the geological structures around KURT using the data obtained from the deep borehole investigation. To achieve the purpose, several geological investigations such as geophysical and borehole fracture surveys were carried out simultaneously. As a result, 7 fracture zones were identified in deep borehole located in the KURT. As one of important parts of site characterization on KURT area, the results will be used to revise the geological model of the study area

Tracer transport in fractured rocks

International Nuclear Information System (INIS)

Tsang, C.F.; Tsang, Y.W.; Hale, F.V.

1988-07-01

Recent interest in the safety of toxic waste underground disposal and nuclear waste geologic repositories has motivated many studies of tracer transport in fractured media. Fractures occur in most geologic formations and introduce a high degree of heterogeneity. Within each fracture, the aperture is not constant in value but strongly varying. Thus for such media, tracer tends to flow through preferred flowpaths or channels within the fractures. Along each of these channels, the aperture is also strongly varying. A detailed analysis is carried out on a 2D single fracture with variable apertures and the flow through channels is demonstrated. The channels defined this way are not rigidly set pathways for tracer transport, but are the preferred flow paths in the sense of stream-tubes in the potential theory. It is shown that such variable-aperture channels can be characterized by an aperture probability distribution function, and not by the exact deterministic geometric locations. We also demonstrate that the 2D tracer transport in a fracture can be calculated by a model of a system of 1D channels characterized by this distribution function only. Due to the channeling character of tracer transport in fractured rock, random point measurements of tracer breakthrough curves may give results with a wide spread in value due to statistical fluctuations. The present paper suggests that such a wide spread can probably be greatly reduced by making line/areal (or multiple) measurements covering a few spatial correlation lengths. 13 refs., 11 figs., 1 tab
FROMS3D: New Software for 3-D Visualization of Fracture Network System in Fractured Rock Masses

Science.gov (United States)

Noh, Y. H.; Um, J. G.; Choi, Y.

2014-12-01

A new software (FROMS3D) is presented to visualize fracture network system in 3-D. The software consists of several modules that play roles in management of borehole and field fracture data, fracture network modelling, visualization of fracture geometry in 3-D and calculation and visualization of intersections and equivalent pipes between fractures. Intel Parallel Studio XE 2013, Visual Studio.NET 2010 and the open source VTK library were utilized as development tools to efficiently implement the modules and the graphical user interface of the software. The results have suggested that the developed software is effective in visualizing 3-D fracture network system, and can provide useful information to tackle the engineering geological problems related to strength, deformability and hydraulic behaviors of the fractured rock masses.
Influence of Subjectivity in Geological Mapping on the Net Penetration Rate Prediction for a Hard Rock TBM

Science.gov (United States)

Seo, Yongbeom; Macias, Francisco Javier; Jakobsen, Pål Drevland; Bruland, Amund

2018-05-01

The net penetration rate of hard rock tunnel boring machines (TBM) is influenced by rock mass degree of fracturing. This influence is taken into account in the NTNU prediction model by the rock mass fracturing factor ( k s). k s is evaluated by geological mapping, the measurement of the orientation of fractures and the spacing of fractures and fracture type. Geological mapping is a subjective procedure. Mapping results can therefore contain considerable uncertainty. The mapping data of a tunnel mapped by three researchers were compared, and the influence of the variation in geological mapping was estimated to assess the influence of subjectivity in geological mapping. This study compares predicted net penetration rates and actual net penetration rates for TBM tunneling (from field data) and suggests mapping methods that can reduce the error related to subjectivity. The main findings of this paper are as follows: (1) variation of mapping data between individuals; (2) effect of observed variation on uncertainty in predicted net penetration rates; (3) influence of mapping methods on the difference between predicted and actual net penetration rate.
geological mapping of the Onkalo open cut

Energy Technology Data Exchange (ETDEWEB)

Talikka, M. [Geological Survey of Finland, Espoo (Finland)

2005-11-15

Posiva Oy and Geological Survey of Finland carried out geological mapping of the ONKALO open cut in the latter half of the year 2004. The study area is located on the Olkiluoto Island in Eurajoki, SW Finland. The study included geological mapping, stereo-photography, and interpretation of 3D images. Fieldwork was carried out during the construction work. The main rock types are vein migmatite and grey gneiss with variation to granitic grey gneiss. The contacts of the rock types are gradual. The vein migmatite consists of fine- to medium-grained mica gneiss paleosome and granite or granite pegmatite neosome. The proportion of the neosome material varies between 15 and 35 percent and the neosome occurs as veins and bands up to ten centimetres in thickness. The granite I granite pegmatite is medium- to coarse-grained and not orientated. Main minerals in the mica gneiss are plagioclase, biotite, quartz, and in the granite / granite pegmatite potassium feldspar, plagioclase, and quartz. The grey gneiss is medium grained and fairly homogenous comprising mainly plagioclase, biotite, and quartz. The granitic grey gneiss contains also potassium feldspar crystals up to five cm in length. The rocks within the study area are generally well preserved. There is, however, a zone of strongly weathered rocks east of the ONKALO open cut. The main structural feature in the study area is S{sub 2} foliation, which is seen in the orientation of biotite grains. The degree of the foliation is weak to medium in the vein migmatite and weak to non-existence in the grey gneiss. The foliation (S{sub 2}) dips 20-70 deg to southeast with an average direction of 150/45 deg. The migmatisation took place during the second deformation phase and possibly proceeded along the lithologic layers. The neosome veins bend irregularly and folding is present in places. The fold axis of the small scale, isoclinal folds dip 50-70 deg to northeast. In fracture mapping a total of 231 fractures were measured
geological mapping of the Onkalo open cut

International Nuclear Information System (INIS)

Talikka, M.

2005-11-01

Posiva Oy and Geological Survey of Finland carried out geological mapping of the ONKALO open cut in the latter half of the year 2004. The study area is located on the Olkiluoto Island in Eurajoki, SW Finland. The study included geological mapping, stereo-photography, and interpretation of 3D images. Fieldwork was carried out during the construction work. The main rock types are vein migmatite and grey gneiss with variation to granitic grey gneiss. The contacts of the rock types are gradual. The vein migmatite consists of fine- to medium-grained mica gneiss paleosome and granite or granite pegmatite neosome. The proportion of the neosome material varies between 15 and 35 percent and the neosome occurs as veins and bands up to ten centimetres in thickness. The granite I granite pegmatite is medium- to coarse-grained and not orientated. Main minerals in the mica gneiss are plagioclase, biotite, quartz, and in the granite / granite pegmatite potassium feldspar, plagioclase, and quartz. The grey gneiss is medium grained and fairly homogenous comprising mainly plagioclase, biotite, and quartz. The granitic grey gneiss contains also potassium feldspar crystals up to five cm in length. The rocks within the study area are generally well preserved. There is, however, a zone of strongly weathered rocks east of the ONKALO open cut. The main structural feature in the study area is S 2 foliation, which is seen in the orientation of biotite grains. The degree of the foliation is weak to medium in the vein migmatite and weak to non-existence in the grey gneiss. The foliation (S 2 ) dips 20-70 deg to southeast with an average direction of 150/45 deg. The migmatisation took place during the second deformation phase and possibly proceeded along the lithologic layers. The neosome veins bend irregularly and folding is present in places. The fold axis of the small scale, isoclinal folds dip 50-70 deg to northeast. In fracture mapping a total of 231 fractures were measured. Field
Regional and site geological frameworks : proposed Deep Geologic Repository, Bruce County, Ontario

Energy Technology Data Exchange (ETDEWEB)

Raven, K.; Sterling, S.; Gaines, S.; Wigston, A. [Intera Engineering Ltd., Ottawa, ON (Canada); Frizzell, R. [Nuclear Waste Management Organization, Toronto, ON (Canada)

2009-07-01

The Nuclear Waste Management Organization is conducting geoscientific studies on behalf of Ontario Power Generation into the proposed development of a Deep Geologic Repository (DGR) for low and intermediate level radioactive waste (L and ILW) at the Bruce site, near Tiverton, Ontario. This paper presented a regional geological framework for the site that was based on a review of regional drilling; structural geology; paleozoic stratigraphy and sedimentology; a 3D geological framework model; a DGR geological site characterization model; bedrock stratigraphy and marker beds; natural fracture frequency data; and formation predictability. The studies have shown that the depth, thickness, orientation and rock quality of the 34 rock formations, members or units that comprise the 840 m thick Paleozoic bedrock sequence at the Bruce site are very uniform and predictable over distances of several kilometres. The proposed DGR will be constructed as an engineered facility comprising a series of underground emplacement rooms at a depth of 680 metres below ground within argillaceous limestones. The geoscientific studies are meant to provide a basis for the development of descriptive geological, hydrogeological and geomechanical models of the DGR site that will facilitate environmental and safety assessments. 11 refs., 3 tabs., 9 figs.
The disposal of intermediate-level radioactive liquid waste by hydraulic fracturing process

International Nuclear Information System (INIS)

Chen Ruilin; Zhou Hanchen; Gao Yuzhu; Qiao Wen; Wang Wentao

1993-01-01

The hydraulic fracturing process is characterized by combination of the treatment with the disposal of ILLW (intermediate-level liquid waste). It is of cement solidification in deep geology stratum. First of all, it is necessary to select a suitable disposal site with detailed information on geology and hydrogeology. The process has such advantages as simple, low cost, large capacity of disposal, safe and reliable in technology. It is an attractive process of ILLW. Since 1980's, the research and the concept design of the hydraulic fracturing process have been initiated for disposal of ILLW. It is demonstrated by the field tests. The authors considered that the geological structure near Sichuan Nuclear Fuel Plant fits the disposal of ILLW by the hydraulic fracturing process
The disposal of intermediate-level radioactive liquid waste by hydraulic fracturing process

Energy Technology Data Exchange (ETDEWEB)

Ruilin, Chen; Hanchen, Zhou; Yuzhu, Gao; Wen, Qiao; Wentao, Wang [Beijing Inst. of Nuclear Engineering (China)

1994-12-31

The hydraulic fracturing process is characterized by combination of the treatment with the disposal of ILLW (intermediate-level liquid waste). It is of cement solidification in deep geology stratum. First of all, it is necessary to select a suitable disposal site with detailed information on geology and hydrogeology. The process has such advantages as simple, low cost, large capacity of disposal, safe and reliable in technology. It is an attractive process of ILLW. Since 1980`s, the research and the concept design of the hydraulic fracturing process have been initiated for disposal of ILLW. It is demonstrated by the field tests. The authors considered that the geological structure near Sichuan Nuclear Fuel Plant fits the disposal of ILLW by the hydraulic fracturing process.
Dating fractures and fracture movement in the Lac du Bonnet Batholith

International Nuclear Information System (INIS)

Gascoyne, M.; Brown, A.; Ejeckam, R.B.; Everitt, R.A.

1997-04-01

This report examines and summarizes all work that has been done from 1980 to the present in determining the age of rock crystallization, fracture initiation, fracture reactivation and rates of fracture movement in the Lac du Bonnet Batholith to provide information for Atomic Energy of Canada Limited's (AECL) Canadian Nuclear Fuel Waste Management Program. Geological and petrographical indicators of relative age (e.g. cross-cutting relationships, sequences of fracture infilling minerals, P-T characteristics of primary and secondary minerals) are calibrated with radiometric age determinations on minerals and whole rock samples, using 87 Rb- 87 Sr, 40 K- 39 Ar, 40 Ar- 39 Ar and fission track methods. Most fractures and fracture zones inclined at low angles are found to be ancient features, first formed in the Early Proterozoic under conditions of deuteric alteration. Following some movement on fractures in the Late Proterozoic and Early Paleozoic, reactivation of fractures during the Pleistocene is established from uranium-series dating methods and use of stable isotopic contents of fracture infilling minerals (mainly calcite). Some indication of movement on fracture zones during the Pleistocene is given by electron spin resonance dating techniques on fault gouge. The slow rate of propagation of fractures is indicated by mineral infillings, their P-T characteristics and U-series calcite ages in a fracture in sparsely fractured rock, accessible from AECL's Underground Research Laboratory. These results collectively indicate that deep fractures observed in the batholith are ancient features and the fracturing and jointing in the upper 200 m is relatively recent (< 1 Ma) and largely a result of stress release. (author)
Addresing environmental challenges to shale gas and hydraulic fracturing

Energy Technology Data Exchange (ETDEWEB)

Vadillo Fernandez, L.; Rodriguez Gomez, V.; Fernadez Naranjo, F.J.

2016-07-01

This article reviews the main issues of unconventional gas extracted by hydraulic fracturing techniques. Topics such as technology, fracturing stages, flowback characterization and alternatives of disposal and reuse, water consumption, physicochemical features of the geological formations, development of the fractures performed by hydraulic fracturing, well flow decline, land use and occupation and induced seismicity are presented, as well as the scientific debate: the potential steps of methane gas and groundwater contamination. (Author)
The Influence of Hydraulic Fracturing on Carbon Storage Performance

Science.gov (United States)

Fu, Pengcheng; Settgast, Randolph R.; Hao, Yue; Morris, Joseph P.; Ryerson, Frederick J.

2017-12-01

Conventional principles of the design and operation of geologic carbon storage (GCS) require injecting CO2 below the caprock fracturing pressure to ensure the integrity of the storage complex. In nonideal storage reservoirs with relatively low permeability, pressure buildup can lead to hydraulic fracturing of the reservoir and caprock. While the GCS community has generally viewed hydraulic fractures as a key risk to storage integrity, a carefully designed stimulation treatment under appropriate geologic conditions could provide improved injectivity while maintaining overall seal integrity. A vertically contained hydraulic fracture, either in the reservoir rock or extending a limited height into the caprock, provides an effective means to access reservoir volume far from the injection well. Employing a fully coupled numerical model of hydraulic fracturing, solid deformation, and matrix fluid flow, we study the enabling conditions, processes, and mechanisms of hydraulic fracturing during CO2 injection. A hydraulic fracture's pressure-limiting behavior dictates that the near-well fluid pressure is only slightly higher than the fracturing pressure of the rock and is insensitive to injection rate and mechanical properties of the formation. Although a fracture contained solely within the reservoir rock with no caprock penetration, would be an ideal scenario, poroelastic principles dictate that sustaining such a fracture could lead to continuously increasing pressure until the caprock fractures. We also investigate the propagation pattern and injection pressure responses of a hydraulic fracture propagating in a caprock subjected to heterogeneous in situ stress. The results have important implications for the use of hydraulic fracturing as a tool for managing storage performance.
A New Method for Fracturing Wells Reservoir Evaluation in Fractured Gas Reservoir

Directory of Open Access Journals (Sweden)

Jianchun Guo

2014-01-01

Full Text Available Natural fracture is a geological phenomenon widely distributed in tight formation, and fractured gas reservoir stimulation effect mainly depends on the communication of natural fractures. Therefore it is necessary to carry out the evaluation of this reservoir and to find out the optimal natural fractures development wells. By analyzing the interactions and nonlinear relationships of the parameters, it establishes three-level index system of reservoir evaluation and proposes a new method for gas well reservoir evaluation model in fractured gas reservoir on the basis of fuzzy logic theory and multilevel gray correlation. For this method, the Gaussian membership functions to quantify the degree of every factor in the decision-making system and the multilevel gray relation to determine the weight of each parameter on stimulation effect. Finally through fuzzy arithmetic operator between multilevel weights and fuzzy evaluation matrix, score, rank, the reservoir quality, and predicted production will be gotten. Result of this new method shows that the evaluation of the production coincidence rate reaches 80%, which provides a new way for fractured gas reservoir evaluation.
Research on geological disposal

Energy Technology Data Exchange (ETDEWEB)

NONE

2013-08-15

The aims of this research are to develop criteria for reviewing reliability and suitability of the result from Preliminary Investigations to be submitted by the implementer, and to establish a basic policy for safety review. For development of reliability and suitability criteria for reviewing the result of Preliminary Investigations, we evaluated the uncertainties and their influence from limited amount of investigations, as well as we identified important procedures during investigations and constructions of models, as follows: (1) uncertainties after limited amount of geological exploration and drilling, (2) influence of uncertainties in regional groundwater flow model, (3) uncertainties of DFN (Discrete Fracture Network) models in the fractured rock, (4) analyzed investigation methods described in implementer's report, and (5) identified important aspects in investigation which need to be reviewed and follow QA (Quality Assurance). For development of reliability and suitability criteria for reviewing the result of Detailed Investigations, we analyzed important aspects in investigation which supplies data to design and safety assessment, as well as studied the applicability of pressure interference data during excavation to verify hydrogeological model. Regarding the research for safety review, uncertainties of geologic process in long time-scale was studied. In FY2012, we started to evaluate the structural stabilities of concrete and bentonite in disposal environment. Finally, we continued to accumulate the knowledge on geological disposal into the database system. (author)
Facilitating the exploitation of ERTS-1 imagery using snow enhancement techniques. [geological fault maps of Massachusetts and Connecticut

Science.gov (United States)

Wobber, F. J. (Principal Investigator); Martin, K. R.; Amato, R. V.; Leshendok, T.

1973-01-01

The author has identified the following significant results. The applications of ERTS-1 imagery for geological fracture mapping regardless of season has been repeatedly confirmed. The enhancement provided by a differential cover of snow increases the number and length of fracture-lineaments which can be detected with ERTS-1 data and accelerates the fracture mapping process for a variety of practical applications. The geological mapping benefits of the program will be realized in geographic areas where data are most needed - complex glaciated terrain and areas of deep residual soils. ERTS-1 derived fracture-lineament maps which provide detail well in excess of existing geological maps are not available in the Massachusetts-Connecticut area. The large quantity of new data provided by ERTS-1 may accelerate and improve field mapping now in progress in the area. Numerous other user groups have requested data on the techniques. This represents a major change in operating philosophy for groups who to data judged that snow obscured geological detail.
Construction of the Geological Model around KURT area based on the surface investigations

International Nuclear Information System (INIS)

Park, Kyung Woo; Koh, Yong Kwon; Kim, Kyung Su; Choi, Jong Won

2009-01-01

To characterize the geological features in the study area for high-level radioactive waste disposal research, KAERI (Korea Atomic Energy Research Institute) has been performing several geological investigations such as geophysical surveys and borehole drillings since 1997. Especially, the KURT (KAERI Underground Research Tunnel) constructed to understand the deep geological environments in 2006. Recently, the deep boreholes, which have 500 m depth inside the left research module of the KURT and 1,000 m depth outside the KURT, were drilled to confirm and validate the results from a geological model. The objective of this research was to investigate hydrogeological conditions using a 3-D geological model around the KURT. The geological analysis from the surface and borehole investigations determined four important geological elements including subsurface weathered zone, low-angled fractures zone, fracture zones and bedrock for the geological model. In addition, the geometries of these elements were also calculated for the three-dimensional model. The results from 3-D geological model in this study will be beneficial to understand hydrogeological environment in the study area as an important part of high-level radioactive waste disposal technology.
Multi-Attribute Seismic/Rock Physics Approach to Characterizing Fractured Reservoirs

Energy Technology Data Exchange (ETDEWEB)

Gary Mavko

2004-11-30

Most current seismic methods to seismically characterize fractures in tight reservoirs depend on a few anisotropic wave propagation signatures that can arise from aligned fractures. While seismic anisotropy can be a powerful fracture diagnostic, a number of situations can lessen its usefulness or introduce interpretation ambiguities. Fortunately, laboratory and theoretical work in rock physics indicates that a much broader spectrum of fracture seismic signatures can occur, including a decrease in P- and S-wave velocities, a change in Poisson's ratio, an increase in velocity dispersion and wave attenuation, as well as well as indirect images of structural features that can control fracture occurrence. The goal of this project was to demonstrate a practical interpretation and integration strategy for detecting and characterizing natural fractures in rocks. The approach was to exploit as many sources of information as possible, and to use the principles of rock physics as the link among seismic, geologic, and log data. Since no single seismic attribute is a reliable fracture indicator in all situations, the focus was to develop a quantitative scheme for integrating the diverse sources of information. The integrated study incorporated three key elements: The first element was establishing prior constraints on fracture occurrence, based on laboratory data, previous field observations, and geologic patterns of fracturing. The geologic aspects include analysis of the stratigraphic, structural, and tectonic environments of the field sites. Field observations and geomechanical analysis indicates that fractures tend to occur in the more brittle facies, for example, in tight sands and carbonates. In contrast, strain in shale is more likely to be accommodated by ductile flow. Hence, prior knowledge of bed thickness and facies architecture, calibrated to outcrops, are powerful constraints on the interpreted fracture distribution. Another important constraint is that
Editorial: Spatial arrangement of faults and opening-mode fractures

Science.gov (United States)

Laubach, Stephen E.; Lamarche, Juliette; Gauthier, Bertand D. M.; Dunne, William M.

2018-03-01

This issue of the Journal of Structural Geology titled Spatial arrangement of faults and opening-mode fractures explores a fundamental characteristic of fault and fracture arrays. The pattern of fault and opening-mode fracture positions in space defines structural heterogeneity and anisotropy in a rock volume, governs how faults and fractures affect fluid flow, and impacts our understanding of the initiation, propagation and interactions during the formation of fracture patterns. This special issue highlights recent progress with respect to characterizing and understanding the spatial arrangements of fault and fracture patterns, providing examples over a wide range of scales and structural settings.
Multi-Site Application of the Geomechanical Approach for Natural Fracture Exploration

Energy Technology Data Exchange (ETDEWEB)

R. L. Billingsley; V. Kuuskraa

2006-03-31

In order to predict the nature and distribution of natural fracturing, Advanced Resources Inc. (ARI) incorporated concepts of rock mechanics, geologic history, and local geology into a geomechanical approach for natural fracture prediction within mildly deformed, tight (low-permeability) gas reservoirs. Under the auspices of this project, ARI utilized and refined this approach in tight gas reservoir characterization and exploratory activities in three basins: the Piceance, Wind River and the Anadarko. The primary focus of this report is the knowledge gained on natural fractural prediction along with practical applications for enhancing gas recovery and commerciality. Of importance to tight formation gas production are two broad categories of natural fractures: (1) shear related natural fractures and (2) extensional (opening mode) natural fractures. While arising from different origins this natural fracture type differentiation based on morphology is sometimes inter related. Predicting fracture distribution successfully is largely a function of collecting and understanding the available relevant data in conjunction with a methodology appropriate to the fracture origin. Initially ARI envisioned the geomechanical approach to natural fracture prediction as the use of elastic rock mechanics methods to project the nature and distribution of natural fracturing within mildly deformed, tight (low permeability) gas reservoirs. Technical issues and inconsistencies during the project prompted re-evaluation of these initial assumptions. ARI's philosophy for the geomechanical tools was one of heuristic development through field site testing and iterative enhancements to make it a better tool. The technology and underlying concepts were refined considerably during the course of the project. As with any new tool, there was a substantial learning curve. Through a heuristic approach, addressing these discoveries with additional software and concepts resulted in a stronger set
Example of fracture characterization in granitic rock

International Nuclear Information System (INIS)

Thorpe, R.K.

1981-03-01

A detailed study of geologic discontinuities for an underground heater test in highly fractured granitic rock is reported. Several prominent shear fractures were delineated within a 6 x 30 x 15 m rock mass by correlating surface mapping and borehole fracture logs. Oblique-reverse faulting is suspected on at least one of the surfaces, and its inferred borehole intercepts appear to be collinear in the direction of slickensiding observed in the field. Four distinct joint sets were identified, one of which coincides with the shear fractures. Another lies nearly horizontal, and two others are steeply inclined and orthogonal. Fracture lengths and spacings for the four joint sets are represented by lognormal probability distributions
Quantifying Discrete Fracture Network Connectivity in Hydraulic Fracturing Stimulation

Science.gov (United States)

Urbancic, T.; Ardakani, E. P.; Baig, A.

2017-12-01

Hydraulic fracture stimulations generally result in microseismicity that is associated with the activation or extension of pre-existing microfractures and discontinuities. Microseismic events acquired under 3D downhole sensor coverage provide accurate event locations outlining hydraulic fracture growth. Combined with source characteristics, these events provide a high quality input for seismic moment tensor inversion and eventually constructing the representative discrete fracture network (DFN). In this study, we investigate the strain and stress state, identified fracture orientation, and DFN connectivity and performance for example stages in a multistage perf and plug completion in a North American shale play. We use topology, the familiar concept in many areas of structural geology, to further describe the relationships between the activated fractures and their effectiveness in enhancing permeability. We explore how local perturbations of stress state lead to the activation of different fractures sets and how that effects the DFN interaction and complexity. In particular, we observe that a more heterogeneous stress state shows a higher percentage of sub-horizontal fractures or bedding plane slips. Based on topology, the fractures are evenly distributed from the injection point, with decreasing numbers of connections by distance. The dimensionless measure of connection per branch and connection per line are used for quantifying the DFN connectivity. In order to connect the concept of connectivity back to productive volume and stimulation efficiency, the connectivity is compared with the character of deformation in the reservoir as deduced from the collective behavior of microseismicity using robustly determined source parameters.

Experience in North America Tight Oil Reserves Development. Horizontal Wells and Multistage Hydraulic Fracturing

Directory of Open Access Journals (Sweden)

R.R. Ibatullin

2017-09-01

Full Text Available The accelerated development of horizontal drilling technology in combination with the multistage hydraulic fracturing of the reservoir has expanded the geological conditions for commercial oil production from tight reservoirs in North America. Geological and physical characteristics of tight reservoirs in North America are presented, as well as a comparison of the geological and physical properties of the reservoirs of the Western Canadian Sedimentary Basin and the Volga-Ural oil and gas province, in particular, in the territory of Tatarstan. The similarity of these basins is shown in terms of formation and deposition. New drilling technologies for horizontal wells (HW and multistage hydraulic fracturing are considered. The drilling in tight reservoirs is carried out exclusively on hydrocarbon-based muds The multi-stage fracturing technology with the use of sliding sleeves, and also slick water – a low-viscous carrier for proppant is the most effective solution for conditions similar to tight reservoirs in the Devonian formation of Tatarstan. Tax incentives which are actively used for the development of HW and multistage fracturing technologies in Canada are described. wells, multistage fracturing
Geological data summary for a borehole drilled between 1991 September 16 and 1991 October 1 for the Transport Properties in Highly Fractured Rock Experiment at the Underground Research Laboratory

Energy Technology Data Exchange (ETDEWEB)

Woodcock, D. R.; Everitt, R. A.

1992-08-01

Borehole 101-013-HG4 was drilled between 1991 September 16 and October 1 from the 130 Level station, as part of the Transport Properties in Highly Fractured Rock Experiment, to explore the geological, hydrogeological and geochemical conditions of the rock mass in an area northwest of the Underground Research Laboratory (URL) shaft. The borehole was drilled to provide information at an intersection with Fracture Zone 2.0, 100 m to the west of boreholes collared from Room 211 of the 240 Level for future solute transport experiments within Fracture Zone 2.0, and to further our understanding of the rock mass in the area. Fracture Zones 2.5, 2.0, 1.9 and a subvertical joint zone in the footwall were all intersected in the borehole. Preliminary results from detailed core logging show that the lithostructural domains intersected in the borehole correlate with those previously identified in the URL shaft, and in nearby exploration boreholes drilled from the 130 Level. The domains are shallow-dipping toward the southeast and are parallel to the three main fracture zones intersected in the borehole.
A review on hydraulic fracturing of unconventional reservoir

Directory of Open Access Journals (Sweden)

Quanshu Li

2015-03-01

Full Text Available Hydraulic fracturing is widely accepted and applied to improve the gas recovery in unconventional reservoirs. Unconventional reservoirs to be addressed here are with very low permeability, complicated geological settings and in-situ stress field etc. All of these make the hydraulic fracturing process a challenging task. In order to effectively and economically recover gas from such reservoirs, the initiation and propagation of hydraulic fracturing in the heterogeneous fractured/porous media under such complicated conditions should be mastered. In this paper, some issues related to hydraulic fracturing have been reviewed, including the experimental study, field study and numerical simulation. Finally the existing problems that need to be solved on the subject of hydraulic fracturing have been proposed.
Geological study of radioactive waste repositories

International Nuclear Information System (INIS)

Oyama, Takahiro; Kitano, Koichi

1987-01-01

The investigation of the stability and the barrier efficiency of the deep underground radioactive waste repositories become a subject of great concern. The purpose of this paper is to gather informations on the geology, engineering geology and hydrogeology in deep galleries in Japan. Conclusion can be summarised as follows: (1) The geological structure of deep underground is complicated. (2) Stress in deep underground is greatly affected by crustal movement. (3) Rock-burst phenomena occur in the deep underground excavations. (4) In spite of deep underground, water occasionally gush out from the fractured zone of rock mass. These conclusion will be useful for feasibility study of underground waste disposal and repositories in Japan. (author)
Evaluation of Different Modeling Approaches to Simulate Contaminant Transport in a Fractured Limestone Aquifer

Science.gov (United States)

Mosthaf, K.; Rosenberg, L.; Balbarini, N.; Broholm, M. M.; Bjerg, P. L.; Binning, P. J.

2014-12-01

It is important to understand the fate and transport of contaminants in limestone aquifers because they are a major drinking water resource. This is challenging because they are highly heterogeneous; with micro-porous grains, flint inclusions, and being heavily fractured. Several modeling approaches have been developed to describe contaminant transport in fractured media, such as the discrete fracture (with various fracture geometries), equivalent porous media (with and without anisotropy), and dual porosity models. However, these modeling concepts are not well tested for limestone geologies. Given available field data and model purpose, this paper therefore aims to develop, examine and compare modeling approaches for transport of contaminants in fractured limestone aquifers. The model comparison was conducted for a contaminated site in Denmark, where a plume of a dissolved contaminant (PCE) has migrated through a fractured limestone aquifer. Multilevel monitoring wells have been installed at the site and available data includes information on spill history, extent of contamination, geology and hydrogeology. To describe the geology and fracture network, data from borehole logs was combined with an analysis of heterogeneities and fractures from a nearby excavation (analog site). Methods for translating the geological information and fracture mapping into each of the model concepts were examined. Each model was compared with available field data, considering both model fit and measures of model suitability. An analysis of model parameter identifiability and sensitivity is presented. Results show that there is considerable difference between modeling approaches, and that it is important to identify the right one for the actual scale and model purpose. A challenge in the use of field data is the determination of relevant hydraulic properties and interpretation of aqueous and solid phase contaminant concentration sampling data. Traditional water sampling has a bias
Gan-Hang tectonic belt and its geologic significance

International Nuclear Information System (INIS)

Deng Jiarui; Zhang Zhiping.

1989-01-01

Gan-Hang tectonic belt is predominantly controlled by Gan-Hang fracture zone. It is mainly composed of Yongfeng-Zhuji downwarping zone, Gan-Hang volcanic activity structural belt and Gan-Hang red basin downfaulted zone. Gan-Hang fracture zone is derived from evolution and development of Shaoxing-Jiangshan deep fracture. It is mainly composed of three deep and large fracture and Fuzhou-Yongfeng large fracture. The fracture zone is a long active belt, but in each active period the geologic structural patterns intensity, depth and forming time were not same. Gan-Hang tectonic belt possesses obvious inheritance. It has always maintained the character of the relative depression or low land since the Caledonian movement. This specific structural environment is favourable for uranium mineralization. At any rate, the formation of this uranium minerogenetic zone has been experiencing a long and complicated processes which were closely associated with long activity of Gan-Hang fracture zone
A geologic analysis of the Side-Looking Airborne Radar imagery of southern New England

Science.gov (United States)

Banks, Paul T.

1975-01-01

Analysis of the side looking airborn radar imagery of Massachusetts, Connecticut and Rhode Island indicates that radar shows the topography in great detail. Since bedrock geologic features are frequently expressed in the topography the radar lends itself to geologic interpretation. The radar was studied by comparisons with field mapped geologic data first at a scale of approximately 1:125,000 and then at a scale of 1:500,000. The larger scale comparison revealed that faults, minor faults, joint sets, bedding and foliation attitudes, lithology and lithologic contacts all have a topographic expression interpretable on the imagery. Surficial geologic features were far less visible on the imagery over most of the area studied. The smaller scale comparisons revealed a pervasive, near orthogonal fracture set cutting all types and ages of rock and trending roughly N40?E and N30?W. In certain places the strike of bedding and foliation attitudes and some lithologic Contacts were visible in addition to the fractures. Fracturing in southern New England is apparently far more important than has been previously recognized. This new information, together with the visibility of many bedding and foliation attitudes and lithologic contacts, indicates the importance of radar imagery in improving the geologic interpretation of an area.
Borehole imaging tool detects well bore fractures

International Nuclear Information System (INIS)

Ma, T.A.; Bigelow, E.L.

1993-01-01

This paper reports on borehole imaging data which can provide high quality geological and petrophysical information to improve fracture identification, dip computations, and lithology determinations in a well bore. The ability to visually quantify the area of a borehole wall occupied by fractures and vugs enhances reservoir characterization and well completion operations. The circumferential borehole imaging log (CBIL) instrument is an acoustic logging device designed to produce a map of the entire borehole wall. The visual images can confirm computed dips and the geological features related to dip. Borehole geometry, including breakout, are accurately described by complete circumferential caliper measurements, which is important information for drilling and completion engineers. In may reservoirs, the images can identify porosity type, bedding characteristics, and petrophysical parameters
The influence of geological loading on the structural integrity of an underground nuclear waste repository

International Nuclear Information System (INIS)

Jakeman, N.

1985-08-01

Stresses are developed in underground nuclear waste repositories as a result of applied loads from geological movements caused by the encroachment of ice sheets or seismic activity for example. These stresses may induce fracturing of the waste matrix, repository vault and nearfield host geology. This fracturing will enhance the advective flow and allow more-rapid transfer of radionuclides from their encapsulation through the repository barriers and nearfield host rock. Geological loads may be applied either gradually as in crustal folding or encroachment of ice sheets, or rapidly as in the case of seismic movements. The analysis outlined in this report is conducted with a view to including the effects of geological loading in a probabilistic repository site assessment computer code such as SYVAC. (author)
Site descriptive modelling Forsmark, stage 2.2. A fracture domain concept as a basis for the statistical modelling of fractures and minor deformation zones, and interdisciplinary coordination

Energy Technology Data Exchange (ETDEWEB)

Olofsson, Isabelle; Simeonov, Assen [Swedish Nuclear Fuel and Waste Manageme nt Co., Stockholm (Sweden); Stephens, Michael [Geological Survey of Sweden (SGU), U ppsala (Sweden); Follin, Sven [SF GeoLogic AB, Taeby (Sweden); Nilsson, Ann-Chatrin [G eosigma AB, Uppsala (Sweden); Roeshoff, Kennert; Lindberg, Ulrika; Lanaro, Flavio [Bergbygg konsult AB, Haesselby (Sweden); Fredriksson, Anders; Persson, Lars [Golder Associat es AB (Sweden)

2007-04-15

The Swedish Nuclear Fuel and Waste Management Company (SKB) is undertaking site characterization at two different locations, Forsmark and Simpevarp/Laxemar, with the objective of siting a final waste repository at depth for spent nuclear fuel. The programme is built upon the development of site descriptive models after each data freeze. This report describes the first attempt to define fracture domains for the Forsmark site modelling in stage 2.2. Already during model version 1.2 at Forsmark, significant spatial variability in the fracture pattern was observed. The variability appeared to be so significant that it provoked the need for a subdivision of the model volume for the treatment of geological and hydrogeological data into sub-volumes. Subsequent analyses of data collected up to data freeze 2.1 led to a better understanding of the site and a concept for the definition of fracture domains based on geological characteristics matured. The main objectives of this report are to identify and describe fracture domains at the site on the basis of geological data and to compile hydrogeological, hydrogeochemical and rock mechanics data within each fracture domain and address the implications of this integration activity. On the basis of borehole data, six fracture domains (FFM01-FFM06) have been recognized inside and immediately around the candidate volume. Three of these domains (FFM01, FFM02 and FFM06) lie inside the target volume for a potential repository in the northwestern part of the candidate area, and need to be addressed in the geological DFN modelling work. The hydrogeological data support the subdivision of the bedrock into fracture domains FFM01, FFM02 and FFM03. Few or no data are available for the other three domains. The hydrogeochemical data also support the subdivision into fracture domains FFM01 and FFM02. Since few data are available from the bedrock between deformation zones inside FFM03, there is little information on the hydrogeochemical
Design philosophy and practice of asymmetrical 3D fracturing and random fracturing: A case study of tight sand gas reservoirs in western Sichuan Basin

Directory of Open Access Journals (Sweden)

Jianchun Guo

2015-03-01

Full Text Available At present two technical models are commonly taken in tight gas reservoir stimulation: conventional massive fracturing and SRV fracturing, but how to select a suitable fracturing model suitable for reservoir characteristics is still a question waiting to be answered. In this paper, based on the analysis of geological characteristics and seepage mechanism of tight gas and shale gas reservoirs, the differences between stimulation philosophy of tight gas reservoirs and shale reservoirs are elucidated, and the concept that a suitable stimulation model should be selected based on reservoir geological characteristics and seepage mechanism aiming at maximally improving the seepage capability of a reservoir. Based on this concept, two fracturing design methods were proposed for two tight gas reservoirs in western Sichuan Basin: asymmetrical 3D fracturing design (A3DF for the middle-shallow Upper Jurassic Penglaizhen Fm stacked reservoirs in which the hydraulic fractures can well match the sand spatial distribution and seepage capability of the reservoirs; SRV fracturing design which can increase fracture randomness in the sandstone and shale laminated reservoirs for the 5th Member of middle-deep Upper Triassic Xujiahe Fm. Compared with that by conventional fracturing, the average production of horizontal wells fractured by A3DF increased by 41%, indicating that A3DF is appropriate for gas reservoir development in the Penglaizhen Fm; meanwhile, the average production per well of the 5th Member of the Xujiahe Fm was 2.25 × 104 m3/d after SRV fracturing, showing that the SRV fracturing is a robust technical means for the development of this reservoir.
Attenuation-difference radar tomography: results of a multiple-plane experiment at the U.S. Geological Survey Fractured-Rock Research Site, Mirror Lake, New Hampshire

Science.gov (United States)

Lane, J.W.; Day-Lewis, F. D.; Harris, J.M.; Haeni, F.P.; Gorelick, S.M.

2000-01-01

Attenuation-difference, borehole-radar tomography was used to monitor a series of sodium chloride tracer injection tests conducted within the FSE, wellfield at the U.S. Geological Survey Fractured-Rock Hydrology Research Site in Grafton County, New Hampshire, USA. Borehole-radar tomography surveys were conducted using the sequential-scanning and injection method in three boreholes that form a triangular prism of adjoining tomographic image planes. Results indicate that time-lapse tomography methods provide high-resolution images of tracer distribution in permeable zones.
US Geological Survey Committee for the Advancement of Science in the Yucca Mountain Project symposium on open-quotes Fractures, Hydrology, and Yucca Mountainclose quotes: Abstracts and summary

International Nuclear Information System (INIS)

Gomberg, J.

1991-01-01

The principal objective of this symposium is to review the available information on fractured/faulted terrains in terms of a coherent hydrogeologic model of ground-water fluid flow and transport, particularly as it pertains to the Yucca Mountain region. This review addresses the influence and significance of fractures on ground-water flow and the transport of conservative-species solutes within the context of the hydrogeologic setting of the Yucca Mountain area. The relations between fluid flow and fractured or faulted host rock are examined integrally from information on geologic, seismologic, hydrologic, and geomechanical properties of the system. The development of new hydrogeologic approaches that incorporate information from this integrated database are contrasted with more standard approaches toward understanding flow in fractured reservoirs. Ground-water flow in both the unsaturated zone and the saturated zone are considered. The application of various models of flow is addressed, examples include porous-media equivalent and discontinuum fracture-network models. Data and interpretations from the Yucca Mountain area are presented to establish a context for information exchange. The symposium includes discussions relevant to technical considerations for characterizing the Yucca Mountain area hydrogeology. On the basis of these discussions, CASY has compiled this document in order to formally summarize the proceedings and communicate recommendations for future directions of research and investigation
An Efficient Mesh Generation Method for Fractured Network System Based on Dynamic Grid Deformation

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Shuli Sun

2013-01-01

Full Text Available Meshing quality of the discrete model influences the accuracy, convergence, and efficiency of the solution for fractured network system in geological problem. However, modeling and meshing of such a fractured network system are usually tedious and difficult due to geometric complexity of the computational domain induced by existence and extension of fractures. The traditional meshing method to deal with fractures usually involves boundary recovery operation based on topological transformation, which relies on many complicated techniques and skills. This paper presents an alternative and efficient approach for meshing fractured network system. The method firstly presets points on fractures and then performs Delaunay triangulation to obtain preliminary mesh by point-by-point centroid insertion algorithm. Then the fractures are exactly recovered by local correction with revised dynamic grid deformation approach. Smoothing algorithm is finally applied to improve the quality of mesh. The proposed approach is efficient, easy to implement, and applicable to the cases of initial existing fractures and extension of fractures. The method is successfully applied to modeling of two- and three-dimensional discrete fractured network (DFN system in geological problems to demonstrate its effectiveness and high efficiency.
Geological Geophysical and structural studies in Mina Ratones (Pluton de Albala)

International Nuclear Information System (INIS)

Perez-Estaun, A.; Carbonell, R.; Marti, D.; Flecha, I.; Escuder Viruete, J.

2002-01-01

Mina Ratones environmental restoration project included petrological, structural,geophysical, hydrogeological and hydrogeochemical studies. The main objective of the geologic-structural and geophysical studies was the Albala granite structural characterization around the Mina Ratones uranium mine. The location of facies, fault zones (faults and dykes) as well as the distribution of some physical properties inside the rock massif was obtained for a granitic black of 900, 500, and 500 m. The geologic-structural and geophysical techniques applied to Mina Ratones provided a multidisciplinary approach for high resolution characterization of rock massif, and the structures potentially containing fluids,able to be applied to the hydrogeological modelling to a particular area. Geological studies included a detailed structural mapping of the area surrounding the mine (1:5,000 scale), the geometric, kinematics, and dynamics analysis of fractures of all scales, the petrology and geochemistry of fault rocks and altered areas surrounding fractures, and the microstructural studies of samples from surface and core lags. The construction of geostatistical models in two and three dimensions had helped to characterize the Mina Ratones rock massif showing the spatial distribution of fault zones, fracture intensity, granite composition heterogeneities, fluid-rock interaction zones, and physical properties. (Author)
Preliminary Geological Survey on the Proposed Sites for the New Research Reactor

International Nuclear Information System (INIS)

Lim, In Cheol; Ha, J. J.; Oh, K. B.

2010-12-01

· Performing the preliminary geological survey on the proposed sites for the new research reactor through the technical service · Ordering a technical service from The Geological Society of Korea · Contents of the geological survey - Confirmation of active fault - Confirmation of a large-scale fracture zone or weak zone - Confirmation of inappropriate items related to the underground water - Confirmation of historical seismicity and instrumental earthquakes data · Synthesized analysis and holding a report meeting · Results of the geological survey - Confirmation of the geological characteristics of the sites and drawing the requirements for the precise geological survey in the future
Evaluation of Fractured Basement Complex Rock Porosity by ...

African Journals Online (AJOL)

current resistivity sounding as complementary geophysical technique to Schlumberger vertical electrical sounding in characterizing fractured geologic systems. Previously, Schlumberger vertical electrical sounding was used to collect data.
Internal fracture heterogeneity in discrete fracture network modelling: Effect of correlation length and textures with connected and disconnected permeability field

Science.gov (United States)

Frampton, A.; Hyman, J.; Zou, L.

2017-12-01

Analysing flow and transport in sparsely fractured media is important for understanding how crystalline bedrock environments function as barriers to transport of contaminants, with important applications towards subsurface repositories for storage of spent nuclear fuel. Crystalline bedrocks are particularly favourable due to their geological stability, low advective flow and strong hydrogeochemical retention properties, which can delay transport of radionuclides, allowing decay to limit release to the biosphere. There are however many challenges involved in quantifying and modelling subsurface flow and transport in fractured media, largely due to geological complexity and heterogeneity, where the interplay between advective and dispersive flow strongly impacts both inert and reactive transport. A key to modelling transport in a Lagrangian framework involves quantifying pathway travel times and the hydrodynamic control of retention, and both these quantities strongly depend on heterogeneity of the fracture network at different scales. In this contribution, we present recent analysis of flow and transport considering fracture networks with single-fracture heterogeneity described by different multivariate normal distributions. A coherent triad of fields with identical correlation length and variance are created but which greatly differ in structure, corresponding to textures with well-connected low, medium and high permeability structures. Through numerical modelling of multiple scales in a stochastic setting we quantify the relative impact of texture type and correlation length against network topological measures, and identify key thresholds for cases where flow dispersion is controlled by single-fracture heterogeneity versus network-scale heterogeneity. This is achieved by using a recently developed novel numerical discrete fracture network model. Furthermore, we highlight enhanced flow channelling for cases where correlation structure continues across
Safety aspects of geological studies around nuclear installations sites

International Nuclear Information System (INIS)

Faure, J.

1988-01-01

The experience of geological studies of about forty french nuclear sites allows to set out the objectives, the phases and the geographic extensions of workings to be realized for confirming a site. The data to be collected for the safety analysis are specified; they concern the local and regional geology, the geotechnical characteristics and the essential elements for evaluating the hazards related to the soil liquefaction, the surface fracturing and in some cases the volcanic risks. It is necessary to follow up the geology during the installation construction and life. 8 refs. (F.M.)
Mass transport in fracture media: impact of the random function model assumed for fractures conductivity

International Nuclear Information System (INIS)

Capilla, J. E.; Rodrigo, J.; Gomez Hernandez, J. J.

2003-01-01

Characterizing the uncertainty of flow and mass transport models requires the definition of stochastic models to describe hydrodynamic parameters. Porosity and hydraulic conductivity (K) are two of these parameters that exhibit a high degree of spatial variability. K is usually the parameter whose variability influence to a more extended degree solutes movement. In fracture media, it is critical to properly characterize K in the most altered zones where flow and solutes migration tends to be concentrated. However, K measurements use to be scarce and sparse. This fact calls to consider stochastic models that allow quantifying the uncertainty of flow and mass transport predictions. This paper presents a convective transport problem solved in a 3D block of fractured crystalline rock. the case study is defined based on data from a real geological formation. As the scarcity of K data in fractures does not allow supporting classical multi Gaussian assumptions for K in fractures, the non multi Gaussian hypothesis has been explored, comparing mass transport results for alternative Gaussian and non-Gaussian assumptions. The latter hypothesis allows reproducing high spatial connectivity for extreme values of K. This feature is present in nature, might lead to reproduce faster solute pathways, and therefore should be modeled in order to obtain reasonably safe prediction of contaminants migration in a geological formation. The results obtained for the two alternative hypotheses show a remarkable impact of the K random function model in solutes movement. (Author) 9 refs

Preliminary Bedrock Geologic Map of the Old Lyme Quadrangle, New London and Middlesex Counties, Connecticut

Science.gov (United States)

Walsh, Gregory J.; Scott, Robert B.; Aleinikoff, John N.; Armstrong, Thomas R.

2006-01-01

This report presents a preliminary map of the bedrock geology of the Old Lyme quadrangle, New London and Middlesex Counties, Connecticut. The map depicts contacts of bedrock geologic units, faults, outcrops, and structural geologic information. The map was published as part of a study of fractured bedrock aquifers and regional tectonics.
Analysis of radionuclide migration through fractures using the stream tube approach

International Nuclear Information System (INIS)

Jong Soon Song; Kun Jai Lee

1988-01-01

An analytical solution for the radionuclide migration in the heterogeneous geologic media is developed by using the Green's function techniques. To take into account the non-homogeneous geologic formation and non-uniform groundwater flow field effectively, a combined fracture/porous media model (in series network) is introduced. The stream tube approach is suggested as an efficient method to analyze groundwater hydrology occurring primarily along the fractures. With this approach, three-dimensional heterogeneous media may be approximated as a network of one-dimensional flow paths (fractures) and the corresponding subsurface transport equations can be solved more easily and efficiently by using the Green's function technique within each unit stream tubes. Also a method of combining the corresponding separate Green's functions to derive an overall Green's function for the flow path network is developed. Analytical solutions with various time-dependent radionuclide release modes for heterogeneous geologic media are obtained and sample calculations are performed for the parametric studies. Comparison with other model shows the validity of the present model. 22 refs.; 11 figs.; 5 tabs
A constrained Delaunay discretization method for adaptively meshing highly discontinuous geological media

Science.gov (United States)

Wang, Yang; Ma, Guowei; Ren, Feng; Li, Tuo

2017-12-01

A constrained Delaunay discretization method is developed to generate high-quality doubly adaptive meshes of highly discontinuous geological media. Complex features such as three-dimensional discrete fracture networks (DFNs), tunnels, shafts, slopes, boreholes, water curtains, and drainage systems are taken into account in the mesh generation. The constrained Delaunay triangulation method is used to create adaptive triangular elements on planar fractures. Persson's algorithm (Persson, 2005), based on an analogy between triangular elements and spring networks, is enriched to automatically discretize a planar fracture into mesh points with varying density and smooth-quality gradient. The triangulated planar fractures are treated as planar straight-line graphs (PSLGs) to construct piecewise-linear complex (PLC) for constrained Delaunay tetrahedralization. This guarantees the doubly adaptive characteristic of the resulted mesh: the mesh is adaptive not only along fractures but also in space. The quality of elements is compared with the results from an existing method. It is verified that the present method can generate smoother elements and a better distribution of element aspect ratios. Two numerical simulations are implemented to demonstrate that the present method can be applied to various simulations of complex geological media that contain a large number of discontinuities.
On the possibility of magnetic nano-markers use for hydraulic fracturing in shale gas mining

Science.gov (United States)

Zawadzki, Jaroslaw; Bogacki, Jan

2016-04-01

Recently shale gas production became essential for the global economy, thanks to fast advances in shale fracturing technology. Shale gas extraction can be achieved by drilling techniques coupled with hydraulic fracturing. Further increasing of shale gas production is possible by improving the efficiency of hydraulic fracturing and assessing the spatial distribution of fractures in shale deposits. The latter can be achieved by adding magnetic markers to fracturing fluid or directly to proppant, which keeps the fracture pathways open. After that, the range of hydraulic fracturing can be assessed by measurement of vertical and horizontal component of earth's magnetic field before and after fracturing. The difference in these components caused by the presence of magnetic marker particles may allow to delineate spatial distribution of fractures. Due to the fact, that subterranean geological formations may contain minerals with significant magnetic properties, it is important to provide to the markers excellent magnetic properties which should be also, independent of harsh chemical and geological conditions. On the other hand it is of great significance to produce magnetic markers at an affordable price because of the large quantities of fracturing fluids or proppants used during shale fracturing. Examining the properties of nano-materials, it was found, that they possess clearly superior magnetic properties, as compared to the same structure but having a larger particle size. It should be then possible, to use lower amount of magnetic marker, to obtain the same effect. Although a research on properties of new magnetic nano-materials is very intensive, cheap magnetic nano-materials are not yet produced on a scale appropriate for shale gas mining. In this work we overview, in detail, geological, technological and economic aspects of using magnetic nano-markers in shale gas mining. Acknowledgment This work was supported by the NCBiR under Grant "Electromagnetic method to
Buoyancy flow in fractures intersecting a nuclear waste repository

International Nuclear Information System (INIS)

Wang, J.S.Y.; Tsang, C.F.

1980-07-01

The thermally induced buoyancy flow in fractured rocks around a nuclear waste repository is of major concern in the evaluation of the regional, long-term impact of nuclear waste disposal in geological formation. In this study, buoyancy flow and the development of convective cells are calculated in vertical fractures passing through or positioned near a repository. Interaction between buoyancy flow and regional hydraulic gradient is studied as a function of time, and the interference of intersecting fractures with each other is also discussed
Fractures and Rock Mechanics, Phase 1

DEFF Research Database (Denmark)

Havmøller, Ole; Krogsbøll, Anette

1997-01-01

The main objectives of the project are to combine geological description of fractures, chalk types and rock mechanical properties, and to investigate whether the chosen outcrops can be used as analogues to reservoir chalks. Five chalk types, representing two outcrop localities: Stevns...
Stress generation and hierarchical fracturing in reactive systems

Science.gov (United States)

Jamtveit, B.; Iyer, K.; Royne, A.; Malthe-Sorenssen, A.; Mathiesen, J.; Feder, J.

2007-12-01

continuous domain division that effectively regenerates fresh surfaces. This process produces the characteristic weathering patterns seen both in Karoo and a wide-range of other geological environments. In summary, hierarchical fracturing leads to a continuous production of fresh reactive surface area during hydration processes such as serpentinization and weathering, and provides first-order rate control during both serptinization and weathering. It thus has wide ranging implications for global geochemical budgets, landscape evolution, and a number of other important geological features.
MULTI-ATTRIBUTE SEISMIC/ROCK PHYSICS APPROACH TO CHARACTERIZING FRACTURED RESERVOIRS

Energy Technology Data Exchange (ETDEWEB)

Gary Mavko

2000-10-01

This project consists of three key interrelated Phases, each focusing on the central issue of imaging and quantifying fractured reservoirs, through improved integration of the principles of rock physics, geology, and seismic wave propagation. This report summarizes the results of Phase I of the project. The key to successful development of low permeability reservoirs lies in reliably characterizing fractures. Fractures play a crucial role in controlling almost all of the fluid transport in tight reservoirs. Current seismic methods to characterize fractures depend on various anisotropic wave propagation signatures that can arise from aligned fractures. We are pursuing an integrated study that relates to high-resolution seismic images of natural fractures to the rock parameters that control the storage and mobility of fluids. Our goal is to go beyond the current state-of-the art to develop and demonstrate next generation methodologies for detecting and quantitatively characterizing fracture zones using seismic measurements. Our study incorporates 3 key elements: (1) Theoretical rock physics studies of the anisotropic viscoelastic signatures of fractured rocks, including up scaling analysis and rock-fluid interactions to define the factors relating fractures in the lab and in the field. (2) Modeling of optimal seismic attributes, including offset and azimuth dependence of travel time, amplitude, impedance and spectral signatures of anisotropic fractured rocks. We will quantify the information content of combinations of seismic attributes, and the impact of multi-attribute analyses in reducing uncertainty in fracture interpretations. (3) Integration and interpretation of seismic, well log, and laboratory data, incorporating field geologic fracture characterization and the theoretical results of items 1 and 2 above. The focal point for this project is the demonstration of these methodologies in the Marathon Oil Company Yates Field in West Texas.
Role of geomechanically grown fractures on dispersive transport in heterogeneous geological formations

NARCIS (Netherlands)

Nick, H.M.; Paluszny, A.; Blunt, M.J.; Matthai, S.K.

2011-01-01

A second order in space accurate implicit scheme for time-dependent advection-dispersion equations and a discrete fracture propagation model are employed to model solute transport in porous media.We study the impact of the fractures on mass transport and dispersion. To model flowand transport,
Do geological field survey and remote sensing record the same fractures? The case of the corallian Loyalty Islands (SW Pacific)

Science.gov (United States)

Thovert, J.; Huaman, D.; Genthon, P.; Adler, P. M.

2010-12-01

The Loyalty Islands are a series of corallian islands uplifted on the elastic bulge of the Australian lithosphere before its subduction at the Vanuatu (formerly New Hebrides) Trench. They are located on the non seismic Loyalty Ridge, which is starting colliding the Vanuatu Trench. The interiors of the islands are covered with dense forests and devoid of outcrops. Lineaments seen on remote sensing data (aerial photos, SPOT 3 and 4, Envisat) are compared with fractures and joints measured on a geological survey near the coasts, where corallian limestones outcrop. Lineaments observed by remote sensing in the inner Islands correspond to one main N110 direction with a large variance of nearly 15° in rms, two minor directions nearly 45° apart (N150 and N60) and no systematic evolution with distance to coasts. The three lineament families are seen near coasts as centimetric to decimetric aperture cracks without evidence of any displacement. However, an extensive geological survey of the fractures near the coast of the islands reveals a clear N135 direction and possibly an EW direction in the Lifou Island, while in the Maré island fractures present a large variance with a single N70 direction. The directions N 135, N110 and N60 are also observed regionally on the seafloor and are presumably present in the basement of the islands. It is shown that lineaments longer than 2000 m are close to the N110 direction and that the mean orientation shifts progressively to reach the N125 direction for L<400 m. Therefore, it is likely that the progressive shift in orientation continues up to the N135 direction observed in the field at the 10-50 m scale. The origin of this apparent difference between field data and remote sensing lineaments is discussed, considering (i) the intense karstification of these islands, where dissolution occurs during infiltration of rainwater, but also due to corrosion mixing at the top and the bottom of the freshwater lens and at its tips near coast. This
Evaluation of modeling approaches to simulate contaminant transport in a fractured limestone aquifer

DEFF Research Database (Denmark)

Mosthaf, Klaus; Fjordbøge, Annika Sidelmann; Broholm, Mette Martina

in fractured limestone aquifers. The model comparison is conducted for a contaminated site in Denmark, where a plume of dissolved PCE has migrated through a fractured limestone aquifer. Field data includes information on spill history, distribution of the contaminant (multilevel sampling), geology...... and hydrogeology. To describe the geology and fracture system, data from borehole logs and cores was combined with an analysis of heterogeneities and fractures from a nearby excavation and pump test data. We present how field data is integrated into the different model concepts. A challenge in the use of field...... and remediation strategies. Each model is compared with field data, considering both model fit and model suitability. Results show a considerable difference between the approaches, and that it is important to select the right one for the actual modeling purpose. The comparison with data showed how much...
Safety Characterization of the Technological Development Plant at Hontomín. Risk Structures: 1. Faults and Fractures

International Nuclear Information System (INIS)

Recreo, F.; Hurtado, A.; Eguilior, S.

2015-01-01

The safe storage of CO2 requires ensuring seal integrity during the time the CO2 will remain in a supercritical state before dissolving as an aqueous phase, CO2-aq. Geological structures such as faults and fractures that affect storage and seal formations can play an important role in the behaviour of the CO2 plume depending on whether the fracture acts as a barrier to the movement of CO2 or as a preferent conduit. As a consequence, a CO2 geological storage affected by faults or fractures represents a higher degree of uncertainty and its complexity will also be greater for the estimation of the dynamic properties of the flow of CO2 than a not fractured reservoir, increasing uncertainties in assessing both performance and safety In this report an analysis is made on the role that faults and fractures can play on the storage formation flow conditions and on the effects on the behaviour of injected CO2, considering different types of fractures in relation to the fracture inclination angle with the plume flow direction and the fracture conductivity, and presents a simplified model of fracture behaviour in a CO2 storage formation which could be mplemented in the safety assessment probabilistic model that CIUDEN is developing in the framework of the ALM/10/017 project. Finally, an application at the Hontomín site is tested based on the current available geological and geophysical information
Fire passage on geomorphic fractures in Cerrado: effect on vegetation

OpenAIRE

Otacílio Antunes Santana; José Marcelo Imaña Encinas; Flávio Luiz de Souza Silveira

2017-01-01

Geomorphic fracture is a natural geologic formation that sometimes forms a deep fissure in the rock with the establishment of soil and vegetation. The objective of this work was to analyze vegetation within geomorphic fractures under the effect of wildfire passage. The biometric variables evaluated before and after fire passage were: diameter, height, leaf area index, timber volume, grass biomass, number of trees and shrubs and of species. Results (in fractures) were compared to adjacent area...
Results from the geological surveys carried out in the Bure laboratory's drifts

International Nuclear Information System (INIS)

Rebours, Herve; Righini, Celine

2010-01-01

Document available in extended abstract form only. After the government's authorization to build and operate an underground laboratory, Andra started the investigation works in November 99 on the Meuse/Haute-Marne URL site. The Meuse/Haute-Marne URL is located at the border of the Champagne-Ardenne and Lorraine regions, on the township of Bure in the Callovo-Oxfordian clay-rich rock. At this place, the layer is about 135 m-thick and lies at a depth of 417 m to 552 m. The construction of the underground installations started in August 2000 with the sinking of the main shaft and the first phase of diggings was completed on the 27 April 2006 when it linked up with the south drift of the laboratory. The laboratory consists in two vertical shafts crossing the 505-m thick sedimentary cover and two levels of experimental drifts dug in Callovo-Oxfordian formation. The first experimental drift dug at -445 m with a drill-and-blast method with steps of 2.4 m. The technical and experimental drifts at the main level (-490 m of depth) were dug with a hydraulic stone crusher. The aims of the geological surveys carried out during the drifts digging are to observe the lateral variation of the lithology, if there is one, to confirm the absence of fault and the geometry of the argillites formation. These works should also allow to characterize the natural or inducted fracturing (EDZ - Excavation Damaged Zone) induced by the digging by a sedimentary and structural follow-up. The EDZ characterization has been established from the geological survey of the drift face and sidewalls carried out from 1 to 5 meters in the drifts, and completed by the structural analysis of the cores of the boreholes drilled for the experimentations' equipments. After the safe keeping of the front, the geological team goes down to carry out the survey which consists in a lithologic and sedimentary mapping, a structural survey for the understanding of joints distribution and EDZ characterization, and
Gas-driven fracture propagation

International Nuclear Information System (INIS)

Nilson, R.H.

1981-10-01

A one-dimensional gas-flow drives a wedge-shaped fracture into a linearly elastic, impermeable half-space which is in uniform compression, sigma/sub infinity/, at infinity. Under a constant driving pressure, p 0 , the fracture/flow system accelerates through a sequence of three self-similar asymptotic regimes (laminar, turbulent, inviscid) in which the fracture grows like an elementary function of time (exponential, near-unity power, and linear; respectively). In each regime, the transport equations are reducible under a separation-of-variables transformation. The integro-differential equations which describe the viscous flows are solved by iterative shooting-methods using expansion techniques to accommodate a zero-pressure singularity at the leading edge of the flow. These numerical results are complemented by an asymptotic analysis for large pressure ratio (N = p 0 /sigma/sub infinity/ → infinity) which exploits the disparity between the fracture-length and penetration-length of the flow. The considered prototypic problem has geologic applications: containment evaluation of underground nuclear tests, explosive stimulation of oil and gas wells, and explosive permeability-enhancement prior to in-situ combustion of coal or oil-shale
Vibrational modes of hydraulic fractures: Inference of fracture geometry from resonant frequencies and attenuation

Science.gov (United States)

Lipovsky, Bradley P.; Dunham, Eric M.

2015-02-01

Oscillatory seismic signals arising from resonant vibrations of hydraulic fractures are observed in many geologic systems, including volcanoes, glaciers and ice sheets, and hydrocarbon and geothermal reservoirs. To better quantify the physical dimensions of fluid-filled cracks and properties of the fluids within them, we study wave motion along a thin hydraulic fracture waveguide. We present a linearized analysis, valid at wavelengths greater than the fracture aperture, that accounts for quasi-static elastic deformation of the fracture walls, as well as fluid viscosity, inertia, and compressibility. In the long-wavelength limit, anomalously dispersed guided waves known as crack or Krauklis waves propagate with restoring force from fracture wall elasticity. At shorter wavelengths, the waves become sound waves within the fluid channel. Wave attenuation in our model is due to fluid viscosity, rather than seismic radiation from crack tips or fracture wall roughness. We characterize viscous damping at both low frequencies, where the flow is always fully developed, and at high frequencies, where the flow has a nearly constant velocity profile away from viscous boundary layers near the fracture walls. Most observable seismic signals from resonating fractures likely arise in the boundary layer crack wave limit, where fluid-solid coupling is pronounced and attenuation is minimal. We present a method to estimate the aperture and length of a resonating hydraulic fracture using both the seismically observed quality factor and characteristic frequency. Finally, we develop scaling relations between seismic moment and characteristic frequency that might be useful when interpreting the statistics of hydraulic fracture events.
Fracture network modelling: an integrated approach for realisation of complex fracture network geometries

International Nuclear Information System (INIS)

Srivastava, R.M.

2007-01-01

In its efforts to improve geological support of the safety case, Ontario Power Generation's Deep Geologic Repository Technology Programme (DGRTP) has developed a procedure (Srivastava, 2002) for creating realistic 3-D fracture network models (FNMs) that honor information typically available at the time of preliminary site characterisation: By accommodating all of the these various pieces of 'hard' and 'soft' data, these FNMs provide a single, coherent and consistent model that can serve the needs of many preliminary site characterisation studies. The detailed, complex and realistic models of 3-D fracture geometry produced by this method can serve as the basis for developing rock property models to be used in flow and transport studies. They can also be used for exploring the suitability of a proposed site by providing quantitative assessments of the probability that a proposed repository with a specified geometry will be intersected by fractures. When integrated with state-of-the-art scientific visualisation, these models can also help in the planning of additional data gathering activities by identifying critical fractures that merit further detailed investigation. Finally, these FNMs can serve as one of the central elements of the presentation and explanation of the Descriptive Conceptual Geosphere Model (DCM) to other interested parties, including non-technical audiences. In addition to being ideally suited to preliminary site characterisation, the approach also readily incorporates field data that may become available during subsequent site investigations, including ground reconnaissance, borehole programmes and other subsurface studies. A single approach can therefore serve the needs of the site characterisation from its inception through several years of data collection and more detailed site-specific investigations, accommodating new data as they become available and updating the FNMs accordingly. The FNMs from this method are probabilistic in the sense that
Fractures on curved surfaces: A classic problem solved

Science.gov (United States)

Balcerak, Ernie

2011-11-01

Sheeting joints—large fractures parallel to a curved rock surface—are common in many locations on Earth, such as the iconic Half Dome in Yosemite National Park in California. Explaining how these fractures form has been a classic unsolved problem in geology. Martel solved the problem by reformulating the static equilibrium equations in a curvilinear reference frame. His analysis shows that compression along a curved surface can induce tension perpendicular to the surface, which can cause subsurface cracks to open. He found that the curvature of a rock surface plays a key role in the formation of fractures.
Aespoe Hard Rock Laboratory. The TASS-tunnel. Geological mapping

Energy Technology Data Exchange (ETDEWEB)

Hardenby, Carljohan (Vattenfall Power Consultant AB (Sweden)); Sigurdsson, Oskar (HAskGeokonsult AB (Sweden))

2010-12-15

The project entitled 'Sealing of tunnel at great depth' (Fintaetning av tunnel paa stort djup) needed a new tunnel in an area as undisturbed as possible and with cross-cutting water-bearing structures. The new tunnel, which was given the name TASS, was excavated on the -450 m level of SKB's Aespoe Hard Rock Laboratory (Aespoe HRL). The length of the tunnel is approximately 80 m and the theoretical tunnel area 19 m2. As is the case with all the other tunnels of the Aespoe HRL, the new tunnel has been geologically mapped. In addition, laser scanning combined with digital photography has been carried out. The tunnel was also used to test various types of explosives, borehole layouts and drilling techniques. The geological mapping of tunnel floor, walls and roof took place on four major occasions when a halt was made in tunnel excavation to allow for various tests. Before the mapping started on these occasions, laser scanning took place. The tunnel faces were mapped after each round (drilling, blasting and unloading). The present report describes the geological features of the tunnel and briefly how the laser scanning was performed. Water-bearing structures have been compared to similar structures in the neighbouring tunnels. The rock type names used here follow the old established Aespoe HRL nomenclature. Narrow (<0.1 m wide) dykes are normally mapped as fracture fillings. The dominating rock type is Aespoe diorite, which constitutes some 90 % of the rock mass. It is mostly mapped as fresh rock. . Minor constituents of the rock mass are fine-grained granite, hybrid rock, pegmatite, quartz veins/lenses and undifferentiated mafic rock. The mapping of fractures and deformation zones considers a number of parameters such as number of fractures, open/healed, width, length, description of fracture surfaces (roughness, planarity, etc), fracture filling, alteration and water. The deformation zones are discriminated into two main categories (&apos
Aespoe Hard Rock Laboratory. The TASS-tunnel. Geological mapping

International Nuclear Information System (INIS)

Hardenby, Carljohan; Sigurdsson, Oskar

2010-12-01

The project entitled 'Sealing of tunnel at great depth' (Fintaetning av tunnel paa stort djup) needed a new tunnel in an area as undisturbed as possible and with cross-cutting water-bearing structures. The new tunnel, which was given the name TASS, was excavated on the -450 m level of SKB's Aespoe Hard Rock Laboratory (Aespoe HRL). The length of the tunnel is approximately 80 m and the theoretical tunnel area 19 m 2 . As is the case with all the other tunnels of the Aespoe HRL, the new tunnel has been geologically mapped. In addition, laser scanning combined with digital photography has been carried out. The tunnel was also used to test various types of explosives, borehole layouts and drilling techniques. The geological mapping of tunnel floor, walls and roof took place on four major occasions when a halt was made in tunnel excavation to allow for various tests. Before the mapping started on these occasions, laser scanning took place. The tunnel faces were mapped after each round (drilling, blasting and unloading). The present report describes the geological features of the tunnel and briefly how the laser scanning was performed. Water-bearing structures have been compared to similar structures in the neighbouring tunnels. The rock type names used here follow the old established Aespoe HRL nomenclature. Narrow (<0.1 m wide) dykes are normally mapped as fracture fillings. The dominating rock type is Aespoe diorite, which constitutes some 90 % of the rock mass. It is mostly mapped as fresh rock. . Minor constituents of the rock mass are fine-grained granite, hybrid rock, pegmatite, quartz veins/lenses and undifferentiated mafic rock. The mapping of fractures and deformation zones considers a number of parameters such as number of fractures, open/healed, width, length, description of fracture surfaces (roughness, planarity, etc), fracture filling, alteration and water. The deformation zones are discriminated into two main categories ('increased fracturing' and

Studies of fracture network geometry of reservoir outcrop analogues from terrestrial lidar data: attempts to quantify spatial variations of fracture characteristics

Science.gov (United States)

Vsemirnova, E. A.; Jones, R. R.; McCaffrey, K. J. W.

2012-04-01

We describe studies analysing terrestrial lidar datasets of fracture systems from a range of reservoir analogues in clastic and carbonate lithologies that represent geological analogues of offshore hydrocarbon reservoirs for the UK continental shelf. As fracture networks (observed here from centimetre to kilometre scale) can significantly affect the permeability of a fractured reservoir, the definition of fracture network geometry at various scales has become an important goal of structural analysis. The main aim of the study has been to extend the investigation of fracture networks in order to quantify spatial variations in fracture parameters in a variety of lithologies. The datasets were pre-processed using RiSCAN PRO software, and then re-sampled and filtered to derive characteristics which are traditionally measured from outcrops, including size distributions, fracture spacing and clustering statistics. This type of analysis can significantly reduce the uncertainty associated with some field fracture network measurements. The digitised fracture networks datasets are then used to investigate various aspects of spatial heterogeneity. A series of fracture maps (joints and faults) were generated at different scales, and fracture trends were studied to test scale dependency of fracture orientations. Multiscale trend analysis was then applied to describe the trend structure of the fracture networks.
Application of artificial intelligence to characterize naturally fractured zones in Hassi Messaoud Oil Field, Algeria

Energy Technology Data Exchange (ETDEWEB)

El Ouahed, Abdelkader Kouider; Mazouzi, Amine [Sonatrach, Rue Djenane Malik, Hydra, Algiers (Algeria); Tiab, Djebbar [Mewbourne School of Petroleum and Geological Engineering, The University of Oklahoma, 100 East Boyd Street, SEC T310, Norman, OK, 73019 (United States)

2005-12-15

In highly heterogeneous reservoirs classical characterization methods often fail to detect the location and orientation of the fractures. Recent applications of Artificial Intelligence to the area of reservoir characterization have made this challenge a possible practice. Such a practice consists of seeking the complex relationship between the fracture index and some geological and geomechanical drivers (facies, porosity, permeability, bed thickness, proximity to faults, slopes and curvatures of the structure) in order to obtain a fracture intensity map using Fuzzy Logic and Neural Network. This paper shows the successful application of Artificial Intelligence tools such as Artificial Neural Network and Fuzzy Logic to characterize naturally fractured reservoirs. A 2D fracture intensity map and fracture network map in a large block of Hassi Messaoud field have been developed using Artificial Neural Network and Fuzzy Logic. This was achieved by first building the geological model of the permeability, porosity and shale volume using stochastic conditional simulation. Then by applying some geomechanical concepts first and second structure directional derivatives, distance to the nearest fault, and bed thickness were calculated throughout the entire area of interest. Two methods were then used to select the appropriate fracture intensity index. In the first method well performance was used as a fracture index. In the second method a Fuzzy Inference System (FIS) was built. Using this FIS, static and dynamic data were coupled to reduce the uncertainty, which resulted in a more reliable Fracture Index. The different geological and geomechanical drivers were ranked with the corresponding fracture index for both methods using a Fuzzy Ranking algorithm. Only important and measurable data were selected to be mapped with the appropriate fracture index using a feed forward Back Propagation Neural Network (BPNN). The neural network was then used to obtain a fracture intensity
Friction of Shear-Fracture Zones

Science.gov (United States)

Riikilä, T. I.; Pylväinen, J. I.; Åström, J.

2017-12-01

A shear fracture of brittle solids under compression undergoes a substantial evolution from the initial microcracking to a fully formed powder-filled shear zone. Experiments covering the entire process are relatively easy to conduct, but they are very difficult to investigate in detail. Numerically, the large strain limit has remained a challenge. An efficient simulation model and a custom-made experimental device are employed to test to what extent a shear fracture alone is sufficient to drive material to spontaneous self-lubrication. A "weak shear zone" is an important concept in geology, and a large number of explanations, specific for tectonic conditions, have been proposed. We demonstrate here that weak shear zones are far more general, and that their emergence only demands that a microscopic, i.e., fragment-scale, stress relaxation mechanism develops during the fracture process.
Acoustic Resonance Characteristics of Rock and Concrete Containing Fractures

Energy Technology Data Exchange (ETDEWEB)

Nakagawa, Seiji [Univ. of California, Berkeley, CA (United States)

1998-08-01

In recent years, acoustic resonance has drawn great attention as a quantitative tool for characterizing properties of materials and detecting defects in both engineering and geological materials. In quasi-brittle materials such as rock and concrete, inherent fractures have a significant influence on their mechanical and hydraulic properties. Most of these fractures are partially open, providing internal boundaries that are visible to propagating seismic waves. Acoustic resonance occurs as a result of constructive and destructive interferences of propagating waves. Therefore the geometrical and mechanical properties of the fracture are also interrogated by the acoustic resonance characteristics of materials. The objective of this dissertation is to understand the acoustic resonance characteristics of fractured rock and concrete.
In-situ fracture mapping using geotomography and brine tracers

International Nuclear Information System (INIS)

Deadrick, F.J.; Ramirez, A.L.; Lytle, R.J.

1981-01-01

The Lawrence Livermore National Laboratory is currently assessing the capabilities of high resolution geophysical methods to characterize geologic sites for the disposal of high level nuclear waste. A successful experiment has recently been performed in which salt water tracers and high frequency electromagnetic waves were utilized to map rock mass fracture zones in-situ. Multiple cross-borehole EM transmissions were used to generate a tomographic image of the fractured rock region between two boreholes. The tomographs obtained correlate well with conventional wireline geophysical logs which can be used to infer the location of fractured zones in the rock mass. This indirect data suggests that the geotomography and brine tracer technique may have merit in mapping fractured zones between boreholes
The Folding and Fracturing of Rocks: A milestone publication in Structural Geology research

Science.gov (United States)

Lisle, Richard; Bastida, Fernando

2017-04-01

In the field of structural geology, the textbook written by John G Ramsay in 1967, reprinted in 2004 and translated into Spanish and Chinese, is the one that has made the greatest research impact. With citations exceeding 4000 (Google Scholar) it far surpasses books by other authors on the subject, with this figure only being approached by his later book Modern Structural Geology (Ramsay and Huber 1983). In this paper we consider the factors that account for the book's success despite the fact that it is a research-level text beyond the comfort zone of most undergraduates. We also take stock of other measures of the book's success; the way it influenced the direction subsequent research effort. We summarize the major advances in structural geology that were prompted by Ramsay's book. Finally we consider the book's legacy. Before the publication of the book in 1967 structural geology had been an activity that had concentrated almost exclusively on geological mapping aimed at establishing the geometrical configuration of rock units. In fact, Ramsay himself has produced beautiful examples of such maps. However, the book made us aware that the geometrical pattern is controlled by the spatial variation of material properties, the boundary conditions, the deformation environment and the temporal variation of stresses. With the arrival of the book Structural Geology came of age as a modern scientific discipline that employed a range of tools such as those of physics, maths and engineering as well as those of geology.
Maximizing Storage Rate and Capacity and Insuring the Environmental Integrity of Carbon Dioxide Sequestration in Geological Reservoirs

Energy Technology Data Exchange (ETDEWEB)

L.A. Davis; A.L. Graham; H.W. Parker; J.R. Abbott; M.S. Ingber; A.A. Mammoli; L.A. Mondy; Quanxin Guo; Ahmed Abou-Sayed

2005-12-07

Maximizing Storage Rate and Capacity and Insuring the Environmental Integrity of Carbon Dioxide Sequestration in Geological Formations The U.S. and other countries may enter into an agreement that will require a significant reduction in CO2 emissions in the medium to long term. In order to achieve such goals without drastic reductions in fossil fuel usage, CO2 must be removed from the atmosphere and be stored in acceptable reservoirs. The research outlined in this proposal deals with developing a methodology to determine the suitability of a particular geologic formation for the long-term storage of CO2 and technologies for the economical transfer and storage of CO2 in these formations. A novel well-logging technique using nuclear-magnetic resonance (NMR) will be developed to characterize the geologic formation including the integrity and quality of the reservoir seal (cap rock). Well-logging using NMR does not require coring, and hence, can be performed much more quickly and efficiently. The key element in the economical transfer and storage of the CO2 is hydraulic fracturing the formation to achieve greater lateral spreads and higher throughputs of CO2. Transport, compression, and drilling represent the main costs in CO2 sequestration. The combination of well-logging and hydraulic fracturing has the potential of minimizing these costs. It is possible through hydraulic fracturing to reduce the number of injection wells by an order of magnitude. Many issues will be addressed as part of the proposed research to maximize the storage rate and capacity and insure the environmental integrity of CO2 sequestration in geological formations. First, correlations between formation properties and NMR relaxation times will be firmly established. A detailed experimental program will be conducted to determine these correlations. Second, improved hydraulic fracturing models will be developed which are suitable for CO2 sequestration as opposed to enhanced oil recovery (EOR
Determination of static moduli in fractured rocks by T-matrix model

Czech Academy of Sciences Publication Activity Database

Chalupa, F.; Vilhelm, J.; Petružálek, Matěj; Bukovská, Z.

2017-01-01

Roč. 22, č. 1 (2017), s. 22-31 ISSN 1335-1788 Institutional support: RVO:67985831 Keywords : fractured rocks * dynamic and static moduli * T-matrix model * elastic wave velocity * well logging Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Geology Impact factor: 0.769, year: 2016 http://actamont.tuke.sk/pdf/2017/n1/3chalupa.pdf
Study of deep fracturation of granitic rock mass. Documentary study

International Nuclear Information System (INIS)

Bles, J.L.; Landry, J.

1984-01-01

This documentary study realized with the financial support of the European Communities and the CEA aims at the utilization of available data for the understanding of the evolution of natural fractures in granitic rocks from the surface to deep underground. The Mt Blanc road tunnel, the EDF's Arc-Isere gallerie, the Auriat deep borehole and the Pyrenean rock mass of Bassies are studied because detailed structural and geological studies have been realized these last 20 years. In this study are more particularly analyzed the relationship between small fractures and large faults, evolution with depth of fracture density and direction, consequences of rock decompression and relationship between fracturation and groundwater
Hot and Steamy Fractures in the Philippines: The Geological Characterization and Permeability Evaluation of Fractures in the Southern Negros Geothermal Field, Philippines

Science.gov (United States)

Pastoriza, L. R.; Holdsworth, R.; McCaffrey, K. J. W.; Dempsey, E. D.; Walker, R. J.; Gluyas, J.; Reyes, J. K.

2016-12-01

Fluid flow pathway characterization is critical to geothermal exploration and exploitation. It requires a good understanding of the structural evolution, fault distribution and fluid flow properties. A dominantly fieldwork-based approach has been used to evaluate the potential fracture permeability characteristics of a typical high-temperature geothermal reservoir in the Southern Negros Geothermal Field, Philippines. This is a liquid-dominated geothermal resource hosted in the andesitic to dacitic Quaternary Cuernos de Negros Volcano in Negros Island. Fieldwork reveals two main fracture groups based on fault rock characteristics, alteration type, relative age of deformation, and associated thermal manifestation, with the younger fractures mainly related to the development of the modern geothermal system. Palaeostress analyses of cross-cutting fault and fracture arrays reveal a progressive counterclockwise rotation of stress axes from the (?)Pliocene up to the present-day, which is consistent with the regional tectonic models. A combined slip and dilation tendency analysis of the mapped faults indicates that NW-SE structures should be particularly promising drilling targets. Frequency versus length and aperture plots of fractures across six to eight orders of magnitude show power-law relationships with a change in scaling exponent in the region of 100 to 500m length-scales. Finally, evaluation of the topology of the fracture branches shows the dominance of Y-nodes that are mostly doubly connected suggesting good connectivity and permeability within the fracture networks. The results obtained in this study illustrate the value of methods that can be globally applied during exploration to better characterize fracture systems in geothermal reservoirs using multiscale datasets.
Geology, geophysics and engineering: a case for synergism

Energy Technology Data Exchange (ETDEWEB)

Gretener, P.E.

1984-06-01

This article uses the example of artificial well fracturing to show how geologists, geophysicists and engineers can benefit from establishing an interdisciplinary dialogue. The term ''Ultimate Recovery'' is shown to be equally applicable to oil production and hard rock mining. While geology and geophysics schools gear their curricula toward the exploration for natural resources, engineers consider exploitation as their exclusive domain. It is proposed that geologists and geophysicists close ranks with the engineers and abolish the current state of separation which is being perpetuated by both sides. It is shown how geological considerations have helped to unravel the process of artificial well stimulation, while well stimulation in turn has provided valuable insights into the present stress conditions in various geological provinces.
The Taavinunnanen gabbro massif. A compilation of results from geological, geophysical and hydrogeological investigations

International Nuclear Information System (INIS)

Gentzschein, B.; Tullborg, E.L.

1985-01-01

The gabbro massif at Taavinunnanen, northern Sweden, is one of the study sites which has been investigated by the Swedish Nuclear Fuel and Waste Management Co (SKB) in order to study different geological environments within the scope of the long-range program for final disposal of spent nuclear fuel. A 700 metres long borehole was drilled within the gabbro. Regional geophysics, geological mapping, petrographical studies, mineralogical studies of rock-forming materials and of fracture fillings as well as hydrogeological tests were carried out. The gabbro shows primary differentiation. Thus, the composition varies from gabbroic to ultrabasic. The gabbro body is intersected by severeal granite dikes. These dikes exhibit a higher hydraulic conductivity and a higher fracture frequency than the gabbro. Comparison of hydraulic conductivity and fracture frequency in the gabbro itself indicates a high degree of sealing of the fractures mainly caused by smectites. Calcite is almost lacking down to a depth of 75 metres, indicating a relatively rapid transport of surface waters down to this depth. With 27 refs. (author)
The fracture zone project - final report

International Nuclear Information System (INIS)

Andersson, Peter

1993-09-01

This report summarizes the work and the experiences gained during the fracture zone project at the Finnsjoen study site. The project is probably the biggest effort, so far, to characterize a major fracture zone in crystalline bedrock. The project was running between 1984-1990 involving a large number of geological, geohydrological, geochemical, and geomechanical investigation. The methods used for identification and characterization are reviewed and discussed in terms of applicability and possible improvements for future investigations. The discussion is exemplified with results from the investigation within the project. Flow and transport properties of the zone determined from hydraulic tests and tracer tests are discussed. A large number of numerical modelling efforts performed within the fracture zone project, the INTRAVAL project, and the SKB91-study are summarized and reviewed. Finally, occurrence of similar zones and the relevance of major low angle fracture zones in connection to the siting of an underground repository is addressed
Dynamic characterisation of the specific surface area for fracture networks

Science.gov (United States)

Cvetkovic, V.

2017-12-01

One important application of chemical transport is geological disposal of high-level nuclear waste for which crystalline rock is a prime candidate for instance in Scandinavia. Interconnected heterogeneous fractures of sparsely fractured rock such as granite, act as conduits for transport of dissolved tracers. Fluid flow is known to be highly channelized in such rocks. Channels imply narrow flow paths, adjacent to essentially stagnant water in the fracture and/or the rock matrix. Tracers are transported along channelised flow paths and retained by minerals and/or stagnant water, depending on their sorption properties; this mechanism is critical for rocks to act as a barrier and ultimately provide safety for a geological repository. The sorbing tracers are retained by diffusion and sorption on mineral surfaces, whereas non-sorbing tracers can be retained only by diffusion into stagnant water of fractures. The retention and transport properties of a sparsely fractured rock will primarily depend on the specific surface area (SSA) of the fracture network which is determined by the heterogeneous structure and flow. The main challenge when characterising SSA on the field-scale is its dependence on the flow dynamics. We first define SSA as a physical quantity and clarify its importance for chemical transport. A methodology for dynamic characterisation of SSA in fracture networks is proposed that relies on three sets of data: i) Flow rate data as obtained by a flow logging procedure; ii) transmissivity data as obtained by pumping tests; iii) fracture network data as obtained from outcrop and geophysical observations. The proposed methodology utilises these data directly as well as indirectly through flow and particle tracking simulations in three-dimensional discrete fracture networks. The methodology is exemplified using specific data from the Swedish site Laxemar. The potential impact of uncertainties is of particular significance and is illustrated for radionuclide
Characterization and evaluation of sites for deep geological disposal of radioactive waste in fractured rocks. Proceedings

Energy Technology Data Exchange (ETDEWEB)

NONE

1998-09-01

The third Aespoe International Seminar was organised by SKB to assess the state of the art in characterisation and evaluation of sites for deep geological disposal of radioactive waste in fractured rocks. Site characterisation and evaluation are important elements for determining the site suitability and long-term safety of a geological repository for radioactive waste disposal. Characterisation work also provides vital information for the design of the underground facility and the engineered barrier system that will contain the waste. The aim of the seminar was to provide a comprehensive assessment of the current know-how on this topic based on world-wide experience from more than 20 years of characterisation and evaluation work. The seminar, which was held at the Aespoe Hard Rock Laboratory was attended by 72 scientists from 10 different countries. The program was divided into four sessions of which two were run in parallel. A total of 38 oral and 5 poster presentations were given at the seminar. The presentations gave a comprehensive summary of recently completed and current work on site characterisation, modelling and application in performance assessments. The results presented at the seminar generally show that significant progress has been made in this field during the last decade. New characterisation techniques have become available, strategies for site investigations have developed further, and model concepts and codes have reached new levels of refinement. Data obtained from site characterisation have also successfully been applied in several site specific performance assessments. The seminar clearly showed that there is a solid scientific basis for assessing the suitability of sites for actual repositories based on currently available site characterisation technology and modelling capabilities. Separate abstracts have been prepared for 38 of the presentations
Advanced hydraulic fracturing methods to create in situ reactive barriers

International Nuclear Information System (INIS)

Murdoch, L.

1997-01-01

This article describes the use of hydraulic fracturing to increase permeability in geologic formations where in-situ remedial action of contaminant plumes will be performed. Several in-situ treatment strategies are discussed including the use of hydraulic fracturing to create in situ redox zones for treatment of organics and inorganics. Hydraulic fracturing methods offer a mechanism for the in-situ treatment of gently dipping layers of reactive compounds. Specialized methods using real-time monitoring and a high-energy jet during fracturing allow the form of the fracture to be influenced, such as creation of assymmetric fractures beneath potential sources (i.e. tanks, pits, buildings) that should not be penetrated by boring. Some examples of field applications of this technique such as creating fractures filled with zero-valent iron to reductively dechlorinate halogenated hydrocarbons, and the use of granular activated carbon to adsorb compounds are discussed
Application of borehole geophysics to fracture identification and characterization in low porosity limestones and dolostones

International Nuclear Information System (INIS)

Haase, C.S.; King, H.L.

1986-01-01

Geophysical logging was conducted in exploratory core holes drilled for geohydrological investigations at three sites used for waste disposal on the US Department of Energy's Oak Ridge Reservation. Geophysical log response was calibrated to borehole geology using the drill core. Subsequently, the logs were used to identify fractures and fractured zones and to characterize the hydrologic activity of such zones. Results of the study were used to identify zones of ground water movement and to select targets for subsequent piezometer and monitoring well installation. Neutron porosity, long- and short-normal resistivity, and density logs exhibit anomalies only adjacent to pervasively fractured zones and rarely exhibit anomalies adjacent to individual fractures, suggesting that such logs have insufficient resolution to detect individual fractures. Spontaneous potential, single point resistance, acoustic velocity, and acoustic variable density logs, however, typically exhibit anomalies adjacent to both individual fractures and fracture zones. Correlation is excellent between fracture density logs prepared from the examination of drill core and fractures identified by the analysis of a suite of geophysical logs that have differing spatial resolution characteristics. Results of the study demonstrate the importance of (1) calibrating geophysical log response to drill core from a site, and (2) running a comprehensive suite of geophysical logs that can evaluate both large- and small-scale rock features. Once geophysical log responses to site-specific geological features have been established, logs provide a means of identifying fracture zones and discriminating between hydrologically active and inactive fracture zones. 9 figs
Mathematical Modeling of Non-Fickian Diffusional Mass Exchange of Radioactive Contaminants in Geological Disposal Formations

Directory of Open Access Journals (Sweden)

Anna Suzuki

2018-01-01

Full Text Available Deep geological repositories for nuclear wastes consist of both engineered and natural geologic barriers to isolate the radioactive material from the human environment. Inappropriate repositories of nuclear waste would cause severe contamination to nearby aquifers. In this complex environment, mass transport of radioactive contaminants displays anomalous behaviors and often produces power-law tails in breakthrough curves due to spatial heterogeneities in fractured rocks, velocity dispersion, adsorption, and decay of contaminants, which requires more sophisticated models beyond the typical advection-dispersion equation. In this paper, accounting for the mass exchange between a fracture and a porous matrix of complex geometry, the universal equation of mass transport within a fracture is derived. This equation represents the generalization of the previously used models and accounts for anomalous mass exchange between a fracture and porous blocks through the introduction of the integral term of convolution type and fractional derivatives. This equation can be applied for the variety of processes taking place in the complex fractured porous medium, including the transport of radioactive elements. The Laplace transform method was used to obtain the solution of the fractional diffusion equation with a time-dependent source of radioactive contaminant.
Performance monitoring of an improved disposal trench in a humid environment in a fractured geology

International Nuclear Information System (INIS)

Mills, D.; Razor, J.

1988-01-01

An engineering evaluation of an improved disposal trench at the Maxey Flats Waste Disposal Site is being conducted in order to demonstrate the feasibility of a burial trench suitable for use at a site in a humid environment and underlain by complex and fractured geologic media. This demonstration is one of several proposed final site stabilization alternatives which will have to be evaluated prior to final site closure. Due to requirements in the Central Midwest Compact Commission, no waste generated as a result of the site closure may be disposed in the Commission's disposal site. Hence, the waste will be disposed on-site. The demonstration trench was constructed and filled with waste during the fall of 1985 with final trench capping being completed in July 1986. Since that time the trench has been evaluated utilizing trench settlement monument elevations, leachate production measurements, leachate radionuclide analysis, chemical tracer analysis and trench water balance. Measurements performed to date indicated that the trench lower infiltration barrier has a permeability of about 1E-7 cm/sec. Water balance measurements indicated that less than one percent of the total rainfall crossed the trench capillary barrier. No settlement of the trench cap has been observed. No liquid has appeared in the leachate collection and monitoring sumps
Preliminary assessment of the healing of fractures in salt

International Nuclear Information System (INIS)

1983-07-01

Natural fractures in salt are not common but have been observed. An assessment is made of whether and under what conditions such fractures regain cohesion (heal). Evidence comes from observations in mines, commercial processing, and laboratory testing of both fractured and granular salt. Healing can take the form of chemical precipitation, ductile injection, and creep closure. Of these, creep closure is of principal interest. Healing is measured in terms of recovered strength and reduced permeability. It is found to increase with increased confining pressure and is greatly enhanced when the salt is in contact with brine. Research at Sandia National Laboratories has demonstrated salt fracture healing in relatively short time periods under conditions consistent with the environment of a geologic repository. 45 references

Preliminary hydrogeological evaluation of geological units from the Mesa de los Santos, Santander

International Nuclear Information System (INIS)

Diaz, Eliana Jimena; Contreras, Nathalia Maria; Pinto, Jorge Eduardo; Velandia, Francisco; Morales, Carlos Julio; Hincapie, Gloria

2009-01-01

This paper present a preliminary hydrogeological evaluation of La Mesa de Los Santos' lithostratigraphic formations, based on the geological mapping, stratigraphy and inventory of water points. All this is supplemented with the analysis of primary porosity by means of the petrographic study and the secondary porosity related statistically with the quantity of fractures of each formation, as well as opening, interconnection and dip. It is made an approach to hydrogeological potential of the geologic outcropping formations in La Mesa de Los Santos, Department of Santander, from the stratigraphic and petrographic analysis and the structural features of these formations. The Upper Member of Los Santos Formation presents the highest potential because of rock's fracturing, continued by the Lower Member with low primary porosity and half fracturing. Silgara Formation, Granito de Pescadero, Jordan Formation and some sections of the sandy levels of the Rosablanca Formation presents a lowest potential due to its low porosity and low grade of fracturing. Low permeability is presented in the Middle Member of the Los Santos Formation, Paja and Tablazo formations, as well as in sectors of the fore mentioned formations and in the Quaternary deposits.
Approach to the fracture hydrology at Stripa: preliminary results

International Nuclear Information System (INIS)

Gale, J.E.; Witherspoon, P.A.

1979-05-01

There are two main problems associated with the concept of geologic storage of radioactive waste in fractured crystalline rock: (1) the thermo-mechanical effects of the heat generated by the waste, and (2) the potential for transport of radioactive materials by the groundwater system. In both problems, fractures play a dominant role. An assessment of the hydraulic and mechanical characteristics of fractued rock requires a careful series of laboratory and field investigations. The complexity of the problem is illustrated by the field studies in a fractured granite that are currently underway in an abandoned iron-ore mine at Stripa, Sweden. Much information is being gathered from an extensive series of boreholes and fracture maps. The approach being taken to integrate these data into an analysis of the fracture hydrology is reviewed and preliminary results from the hydrology program are presented. 13 figures
Tuning Fractures With Dynamic Data

Science.gov (United States)

Yao, Mengbi; Chang, Haibin; Li, Xiang; Zhang, Dongxiao

2018-02-01

Flow in fractured porous media is crucial for production of oil/gas reservoirs and exploitation of geothermal energy. Flow behaviors in such media are mainly dictated by the distribution of fractures. Measuring and inferring the distribution of fractures is subject to large uncertainty, which, in turn, leads to great uncertainty in the prediction of flow behaviors. Inverse modeling with dynamic data may assist to constrain fracture distributions, thus reducing the uncertainty of flow prediction. However, inverse modeling for flow in fractured reservoirs is challenging, owing to the discrete and non-Gaussian distribution of fractures, as well as strong nonlinearity in the relationship between flow responses and model parameters. In this work, building upon a series of recent advances, an inverse modeling approach is proposed to efficiently update the flow model to match the dynamic data while retaining geological realism in the distribution of fractures. In the approach, the Hough-transform method is employed to parameterize non-Gaussian fracture fields with continuous parameter fields, thus rendering desirable properties required by many inverse modeling methods. In addition, a recently developed forward simulation method, the embedded discrete fracture method (EDFM), is utilized to model the fractures. The EDFM maintains computational efficiency while preserving the ability to capture the geometrical details of fractures because the matrix is discretized as structured grid, while the fractures being handled as planes are inserted into the matrix grids. The combination of Hough representation of fractures with the EDFM makes it possible to tune the fractures (through updating their existence, location, orientation, length, and other properties) without requiring either unstructured grids or regridding during updating. Such a treatment is amenable to numerous inverse modeling approaches, such as the iterative inverse modeling method employed in this study, which is
Comparison of pressure transient response in intensely and sparsely fractured reservoirs

Energy Technology Data Exchange (ETDEWEB)

Johns, R.T.

1989-04-01

A comprehensive analytical model is presented to study the pressure transient behavior of a naturally fractured reservoir with a continuous matrix block size distribution. Geologically realistic probability density functions of matrix block size are used to represent reservoirs of varying fracture intensity and uniformity. Transient interporosity flow is assumed and interporosity skin is incorporated. Drawdown and interference pressure transient tests are investigated. The results show distinctions in the pressure response from intensely and sparsely fractured reservoirs in the absence of interporosity skin. Also, uniformly and nonuniformly fractured reservoirs exhibit distinct responses, irrespective of the degree of fracture intensity. The pressure response in a nonuniformly fractured reservoir with large block size variability, approaches a nonfractured (homogeneous) reservoir response. Type curves are developed to estimate matrix block size variability and the degree of fracture intensity from drawdown and interference well tests.
Determination of Fracture System Geometry from Well Testing

International Nuclear Information System (INIS)

Doe, T.W.

1994-01-01

In this paper, the research and development for the description of the hydraulic geometry of fracture networks are discussed. The studies on fracture networks have developed on the premise that the structural geological information on fracture geometries could be used to develop the realistic models of flow. It has been widely recognized that a relatively small portion of natural fracture networks controls a major portion of groundwater flow. The key to efficient network modeling is to identify that portion of networks. It is the main purpose of this paper to discuss the methods for characterizing the hydraulic geometry of fracture flow systems. The methods described in this paper cover three approaches for defining the hydraulic geometry of fracture networks, that is, the determination of conductive fracture frequency in boreholes, the use of transient pressure and flow responses in single holes, and the use of cross hole test to assess connectivity. The information which can be obtained by each test is shown. Flow logging, well test distribution and conductive fracture frequency are discussed. The transient analysis of single hole well test and the cross hole analysis of well test for fracture network geometry are reported. The data taken by various methods together can provide network characterization. (K.I.)
Origin of Permeability and Structure of Flows in Fractured Media

Science.gov (United States)

De Dreuzy, J.; Darcel, C.; Davy, P.; Erhel, J.; Le Goc, R.; Maillot, J.; Meheust, Y.; Pichot, G.; Poirriez, B.

2013-12-01

After more than three decades of research, flows in fractured media have been shown to result from multi-scale geological structures. Flows result non-exclusively from the damage zone of the large faults, from the percolation within denser networks of smaller fractures, from the aperture heterogeneity within the fracture planes and from some remaining permeability within the matrix. While the effect of each of these causes has been studied independently, global assessments of the main determinisms is still needed. We propose a general approach to determine the geological structures responsible for flows, their permeability and their organization based on field data and numerical modeling [de Dreuzy et al., 2012b]. Multi-scale synthetic networks are reconstructed from field data and simplified mechanical modeling [Davy et al., 2010]. High-performance numerical methods are developed to comply with the specificities of the geometry and physical properties of the fractured media [Pichot et al., 2010; Pichot et al., 2012]. And, based on a large Monte-Carlo sampling, we determine the key determinisms of fractured permeability and flows (Figure). We illustrate our approach on the respective influence of fracture apertures and fracture correlation patterns at large scale. We show the potential role of fracture intersections, so far overlooked between the fracture and the network scales. We also demonstrate how fracture correlations reduce the bulk fracture permeability. Using this analysis, we highlight the need for more specific in-situ characterization of fracture flow structures. Fracture modeling and characterization are necessary to meet the new requirements of a growing number of applications where fractures appear both as potential advantages to enhance permeability and drawbacks for safety, e.g. in energy storage, stimulated geothermal energy and non-conventional gas productions. References Davy, P., et al. (2010), A likely universal model of fracture scaling and
Stress dependence of permeability of intact and fractured shale cores.

Science.gov (United States)

van Noort, Reinier; Yarushina, Viktoriya

2016-04-01

Whether a shale acts as a caprock, source rock, or reservoir, understanding fluid flow through shale is of major importance for understanding fluid flow in geological systems. Because of the low permeability of shale, flow is thought to be largely confined to fractures and similar features. In fracking operations, fractures are induced specifically to allow for hydrocarbon exploration. We have constructed an experimental setup to measure core permeabilities, using constant flow or a transient pulse. In this setup, we have measured the permeability of intact and fractured shale core samples, using either water or supercritical CO2 as the transporting fluid. Our measurements show decreasing permeability with increasing confining pressure, mainly due to time-dependent creep. Furthermore, our measurements show that for a simple splitting fracture, time-dependent creep will also eliminate any significant effect of this fracture on permeability. This effect of confinement on fracture permeability can have important implications regarding the effects of fracturing on shale permeability, and hence for operations depending on that.
Fire passage on geomorphic fractures in Cerrado: effect on vegetation

Directory of Open Access Journals (Sweden)

Otacílio Antunes Santana

2017-01-01

Full Text Available Geomorphic fracture is a natural geologic formation that sometimes forms a deep fissure in the rock with the establishment of soil and vegetation. The objective of this work was to analyze vegetation within geomorphic fractures under the effect of wildfire passage. The biometric variables evaluated before and after fire passage were: diameter, height, leaf area index, timber volume, grass biomass, number of trees and shrubs and of species. Results (in fractures were compared to adjacent areas (control. The effect of wildfire passage on vegetation within geomorphic fractures was not significant because fire followed plant biomass bed and when it met the fracture (wetter, it changed from soil surface to canopy surface (jump fire effect, affecting without significance the number of plants or species; so, fracture could be plants refuge against fire passage. We could infer in our experimental model that quality of plant biomass bed could be more significant than quantity, and microclimate variability recruits plants to the refuge (geomorphic fracture.
Geological evolution and uranium mineralisation of Chhinjra area, Kulu district, Himachal Pradesh

Energy Technology Data Exchange (ETDEWEB)

Sen, D B; Kumar, Suresh; Gangadharan, G R [Department of Atomic Energy, New Delhi (India). Atomic Minerals Div.

1995-08-01

Several shear-controlled and fracture-filled/disseminated type uranium occurrences are known in the Rampur window. This paper presents the geology and genetic aspects of fracture-filled type of mineralisation in Chhinjra area on the basis of recent stratigraphical, geochronological and tectonic data. Based on the angular unconformity between Manikaran quartzites and overlying chlorite phyllites, the geological evolution of Chhinjra area has been reconstructed in two stages: pre-unconformity and post-unconformity. Each stage is characterised by different phases of deformation with typical structural style and accompanying mineralisation processes. Four major tectonic events can be recognised here, namely 2500 Ma, 1200 Ma, 700 Ma and 55 Ma. Each event has left its imprint on the rocks as well as uranium mineralisation of Chhinjra area. (author). 14 refs., 4 figs.
Reflection of block neotectonics in geological structure of paleogene strata of Chornobyl exclusion zone

International Nuclear Information System (INIS)

Skvortsov, V.V.; Oleksandrova, N.V.; Khodorovs'kij, A.Ya.

2014-01-01

Neotectonic block differentiation of Chernobyl Exclusion zone area was fixed by the results of the geological and structure analysis of paleogene strata in complex with the space survey data interpretation. Structural plan of the latest tectonic movements had a block character; it was shown by the fracture systems, which represent the components of known regional tectonic zones of various trends and are found in the features of phanerozoic rock mass structure. The territory under study is divided into two parts - the northern one, where in the neotectonic movements are generally more intensive with manifestation practically all over the fracture zones, and the southern part, where in the newest breaks belong mainly to submeridional also to south-western regional fracture zones. The southern part of the Exclusion zone, as a whole, holds the greatest promise by comparison with the northern one in the view of neotectonic criteria regarding the geological repository siting for radioactive waste disposal
Fracture detection, mapping, and analysis of naturally fractured gas reservoirs using seismic technology. Final report, November 1995

Energy Technology Data Exchange (ETDEWEB)

NONE

1995-10-01

Many basins in the Rocky Mountains contain naturally fractured gas reservoirs. Production from these reservoirs is controlled primarily by the shape, orientation and concentration of the natural fractures. The detection of gas filled fractures prior to drilling can, therefore, greatly benefit the field development of the reservoirs. The objective of this project was to test and verify specific seismic methods to detect and characterize fractures in a naturally fractured reservoir. The Upper Green River tight gas reservoir in the Uinta Basin, Northeast Utah was chosen for the project as a suitable reservoir to test the seismic technologies. Knowledge of the structural and stratigraphic geologic setting, the fracture azimuths, and estimates of the local in-situ stress field, were used to guide the acquisition and processing of approximately ten miles of nine-component seismic reflection data and a nine-component Vertical Seismic Profile (VSP). Three sources (compressional P-wave, inline shear S-wave, and cross-line, shear S-wave) were each recorded by 3-component (3C) geophones, to yield a nine-component data set. Evidence of fractures from cores, borehole image logs, outcrop studies, and production data, were integrated with the geophysical data to develop an understanding of how the seismic data relate to the fracture network, individual well production, and ultimately the preferred flow direction in the reservoir. The multi-disciplinary approach employed in this project is viewed as essential to the overall reservoir characterization, due to the interdependency of the above factors.
Geology of the Southern Utopia Planitia Highland-Lowland Boundary Plain: First Year Results and Second Year Plan

Science.gov (United States)

Skinner, J. A., Jr.; Tanaka, K. L.; Hare, T. M.

2008-01-01

The southern Utopia highland-lowland boundary (HLB) extends >1500 km westward from northern Nepenthes Mensae to the topographic saddle that separates Isidis and Utopia Planitiae. It contains bench-like platforms that contain depressions, pitted cones (some organized into arcuate chains and thumbprint terrain), isolated domes, lineated depressions, buried circular depressions, ring fractures, polygonal fractures, and other locally- to regionally-dispersed landforms [1]. The objective of our mapping project is to clarify the geologic evolution of the southern Utopia Planitia HLB by identifying the geologic, structural, and stratigraphic relationships of surface materials in MTMs 10237, 15237, 20237, 10242, 15242, 20242, 10247, 15247, and 20247.
Modeling contaminant plumes in fractured limestone aquifers

DEFF Research Database (Denmark)

Mosthaf, Klaus; Brauns, Bentje; Fjordbøge, Annika Sidelmann

Determining the fate and transport of contaminant plumes from contaminated sites in limestone aquifers is important because they are a major drinking water resource. This is challenging because they are often heavily fractured and contain chert layers and nodules, resulting in a complex transport...... model. The paper concludes with recommendations on how to identify and employ suitable models to advance the conceptual understanding and as decision support tools for risk assessment and the planning of remedial actions....... behavior. Improved conceptual models are needed for this type of site. Here conceptual models are developed by combining numerical models with field data. Several types of fracture flow and transport models are available for the modeling of contaminant transport in fractured media. These include...... the established approaches of the equivalent porous medium, discrete fracture and dual continuum models. However, these modeling concepts are not well tested for contaminant plume migration in limestone geologies. Our goal was to develop and evaluate approaches for modeling the transport of dissolved contaminant...
Seismological and geological investigation for earthquake hazard in the Greater Accra Metropolitan Area

International Nuclear Information System (INIS)

Doku, M. S.

2013-07-01

A seismological and geological investigation for earthquake hazard in the Greater Accra Metropolitan Area was undertaken. The research was aimed at employing a methematical model to estimate the seismic stress for the study area by generating a complete, unified and harmonized earthquake catalogue spanning 1615 to 2012. Seismic events were souced from Leydecker, G. and P. Amponsah, (1986), Ambraseys and Adams, (1986), Amponsah (2008), Geological Survey Department, Accra, Ghana, Amponsah (2002), National Earthquake Information Service, United States Geological Survey, Denver, Colorado 80225, USA, the International Seismological Centre and the National Data Centre of the Ghana Atomic Energy Commission. Events occurring in the study area were used to create and Epicentral Intensity Map and a seismicity map of the study area after interpolation of missing seismic magnitudes. The least square method and the maximum likelihood estimation method were employed to evaluate b-values of 0.6 and 0.9 respectively for the study area. A thematic map of epicentral intensity superimposed on the geology of the study area was also developed to help understand the relationship between the virtually fractured, jointed and sheared geology and the seismic events. The results obtained are indicative of the fact that the stress level of GAMA has a telling effect on its seismicity and also the events are prevalents at fractured, jointed and sheared zones. (au)
Seismic Fracture Characterization Methodologies for Enhanced Geothermal Systems

Energy Technology Data Exchange (ETDEWEB)

Queen, John H. [Hi-Geophysical, Inc., Ponca, OK (United States)

2016-05-09

Executive Summary The overall objective of this work was the development of surface and borehole seismic methodologies using both compressional and shear waves for characterizing faults and fractures in Enhanced Geothermal Systems. We used both surface seismic and vertical seismic profile (VSP) methods. We adapted these methods to the unique conditions encountered in Enhanced Geothermal Systems (EGS) creation. These conditions include geological environments with volcanic cover, highly altered rocks, severe structure, extreme near surface velocity contrasts and lack of distinct velocity contrasts at depth. One of the objectives was the development of methods for identifying more appropriate seismic acquisition parameters for overcoming problems associated with these geological factors. Because temperatures up to 300º C are often encountered in these systems, another objective was the testing of VSP borehole tools capable of operating at depths in excess of 1,000 m and at temperatures in excess of 200º C. A final objective was the development of new processing and interpretation techniques based on scattering and time-frequency analysis, as well as the application of modern seismic migration imaging algorithms to seismic data acquired over geothermal areas. The use of surface seismic reflection data at Brady's Hot Springs was found useful in building a geological model, but only when combined with other extensive geological and geophysical data. The use of fine source and geophone spacing was critical in producing useful images. The surface seismic reflection data gave no information about the internal structure (extent, thickness and filling) of faults and fractures, and modeling suggests that they are unlikely to do so. Time-frequency analysis was applied to these data, but was not found to be significantly useful in their interpretation. Modeling does indicate that VSP and other seismic methods with sensors located at depth in wells will be the most
Evaluation of geologic and geophysical techniques for surface-to-subsurface projections of geologic characteristics in crystalline rock

International Nuclear Information System (INIS)

1985-07-01

Granitic and gneissic rock complexes are being considered for their potential to contain and permanently isolate high-level nuclear waste in a deep geologic repository. The use of surface geologic and geophysical techniques has several advantages over drilling and testing methods for geologic site characterization in that the techniques are typically less costly, provide data over a wider area, and do not jeopardize the physical integrity of a potential repository. For this reason, an extensive literature review was conducted to identify appropriate surface geologic and geophysical techniques that can be used to characterize geologic conditions in crystalline rock at proposed repository depths of 460 to 1,220 m. Characterization parameters such as rock quality; fracture orientation, spacing; and aperture; depths to anomalies; degree of saturation; rock body dimensions; and petrology are considered to be of primary importance. Techniques reviewed include remote sensing, geologic mapping, petrographic analysis, structural analysis, gravity and magnetic methods, electrical methods, and seismic methods. Each technique was reviewed with regard to its theoretical basis and field application; geologic parameters that can be evaluated; advantages and limitations, and, where available, case history applications in crystalline rock. Available information indicates that individual techniques provide reliable information on characteristics at the surface, but have limited success in projections to depths greater that approximately 100 m. A combination of integrated techniques combines with data from a limited number of boreholes would significantly improve the reliability and confidence of early characterization studies to provide qualitative rock body characteristics for region-to-area and area-to-site selection evaluations. 458 refs., 32 figs., 14 tabs
Wetting phase permeability in a partially saturated horizontal fracture

International Nuclear Information System (INIS)

Nicholl, M.J.; Glass, R.J.

1994-01-01

Fractures within geologic media can dominate the hydraulic properties of the system. Therefore, conceptual models used to assess the potential for radio-nuclide migration in unsaturated fractured rock such as that composing Yucca Mountain, Nevada, must be consistent with flow processes in individual fractures. A major obstacle to the understanding and simulation of unsaturated fracture flow is the paucity of physical data on both fracture aperture structure and relative permeability. An experimental procedure is developed for collecting detailed data on aperture and phase structure from a transparent analog fracture. To facilitate understanding of basic processes and provide a basis for development of effective property models, the simplest possible rough-walled fracture is used. Stable phase structures of varying complexity are created within the horizontal analog fracture. Wetting phase permeability is measured under steady-state conditions. A process based model for wetting phase relative permeability is then explored. Contributions of the following processes to reduced wetting phase permeability under unsaturated conditions are considered: reduction in cross-sectional flow area, increased path length, localized flow restriction, and preferential occupation of large apertures by the non-wetting phase
Geologic and radiometric study in the Picacho, Arizpe's Municipality, Sorora (Mexico) area

International Nuclear Information System (INIS)

Garcia y Barragan, J.C.

1975-01-01

This research work was aimed chiefly at studying the geology and radiometry of the El Picacho area in order to establish its uranium mineralization potential. Another purpose was to ascertain the factors favouring deposition of radioactive material in areas bordering on the Sierra del Manzanal, where the work was carried out. Detailed geological-radiometric surveys were made, both inside the El Picacho mine and at the surface. The geological surveys were carried out by means of compass bearings and stadia, while scintillometers and spectrometers were used for the radiometric studies. The work was supported by a general geological exploration of the central part of the Serra del Manzanal. To ascertain the radiometric anomalies, the distribution of the population of values was determined by statistical methods, the frequency, cumulative frequency and frequency percentage being evaluated for that purpose. The geological survey at the El Picacho mine revealed a group of fractures enclosing the following minerals: torbernite, iriginite and autunite. These fractures are no thicker than 5 cm and tend to wedge out after 3 meters. Primary uraniferous ore is likely to be found in this zone, so surveys based on (a) radon gas emanometry and (b) sediment geochemistry in the Siera del Manzanal are recommended. The basic data relating to this area could be supplemented by mineragraphic and X-ray studies, which would provide a fuller picture of the class of mineralogical species and of the paragenesis of radioactive material presnent in the zone. (author)
Tectonics of ridge-transform intersections at the Kane fracture zone

Science.gov (United States)

Karson, J. A.; Dick, H. J. B.

1983-03-01

The Kane Transform offsets spreading-center segments of the Mid-Atlantic Ridge by about 150 km at 24° N latitude. In terms of its first-order morphological, geological, and geophysical characteristics it appears to be typical of long-offset (>100 km), slow-slipping (2 cm yr-1) ridge-ridge transform faults. High-resolution geological observations were made from deep-towed ANGUS photographs and the manned submersible ALVIN at the ridge-transform intersections and indicate similar relationships in these two regions. These data indicate that over a distance of about 20 km as the spreading axes approach the fracture zone, the two flanks of each ridge axis behave in very different ways. Along the flanks that intersect the active transform zone the rift valley floor deepens and the surface expression of volcanism becomes increasingly narrow and eventually absent at the intersection where only a sediment-covered ‘nodal basin’ exists. The adjacent median valley walls have structural trends that are oblique to both the ridge and the transform and have as much as 4 km of relief. These are tectonically active regions that have only a thin (young volcanics passes laterally into median valley walls with a simple block-faulted character where only volcanic rocks have been found. Along strike toward the fracture zone, the youngest volcanics form linear constructional volcanic ridges that transect the entire width of the fracture zone valley. These volcanics are continuous with the older-looking, slightly faulted volcanic terrain that floors the non-transform fracture zone valleys. These observations document the asymmetric nature of seafloor spreading near ridge-transform intersections. An important implication is that the crust and lithosphere across different portions of the fracture zone will have different geological characteristics. Across the active transform zone two lithosphere plate edges formed at ridge-transform corners are faulted against one another. In the non
Universal Linear Scaling of Permeability and Time for Heterogeneous Fracture Dissolution

Science.gov (United States)

Wang, L.; Cardenas, M. B.

2017-12-01

Fractures are dynamically changing over geological time scale due to mechanical deformation and chemical reactions. However, the latter mechanism remains poorly understood with respect to the expanding fracture, which leads to a positively coupled flow and reactive transport processes, i.e., as a fracture expands, so does its permeability (k) and thus flow and reactive transport processes. To unravel this coupling, we consider a self-enhancing process that leads to fracture expansion caused by acidic fluid, i.e., CO2-saturated brine dissolving calcite fracture. We rigorously derive a theory, for the first time, showing that fracture permeability increases linearly with time [Wang and Cardenas, 2017]. To validate this theory, we resort to the direct simulation that solves the Navier-Stokes and Advection-Diffusion equations with a moving mesh according to the dynamic dissolution process in two-dimensional (2D) fractures. We find that k slowly increases first until the dissolution front breakthrough the outbound when we observe a rapid k increase, i.e., the linear time-dependence of k occurs. The theory agrees well with numerical observations across a broad range of Peclet and Damkohler numbers through homogeneous and heterogeneous 2D fractures. Moreover, the theory of linear scaling relationship between k and time matches well with experimental observations of three-dimensional (3D) fractures' dissolution. To further attest to our theory's universality for 3D heterogeneous fractures across a broad range of roughness and correlation length of aperture field, we develop a depth-averaged model that simulates the process-based reactive transport. The simulation results show that, regardless of a wide variety of dissolution patterns such as the presence of dissolution fingers and preferential dissolution paths, the linear scaling relationship between k and time holds. Our theory sheds light on predicting permeability evolution in many geological settings when the self

Geological site selection studies in Precambrian crystalline rocks in Finland

International Nuclear Information System (INIS)

Vuorela, P.

1988-01-01

In general geological investigations made since 1977 the Finnish crystalline bedrock has been determined to be suitable for the final disposal of the spent nuclear fuel. Regional investigations have been mainly based on already existing geological studies. Special attention has been paid on the international geological Finland as the Baltic Shield is stiff and stable and situated far outside the zones of volcanic and seismic activity. The present day crustal movements in Finland are related to landuplift process. Movements and possible faults in the bedrock follow fracture zones which devide the bedrock into mosaiclike blocks. As compared to small scale geological maps the bedrock blocks are often indicated as large granite rock formations which are less broken than the surrounding rocks, though the age of granite formations is at least 1500 millions of years. The large bedrock blocks (20-300 km 2 ) are divided to smaller units by different magnitudes of fractures and these smaller bedrock units (5-20 km 2 ) have been selected for further site selection investigations. At the first stage of investigations 327 suitable regional bedrock blocks have been identified on the basis of Landsat-1 winter and summer mosaics of Finland. After two years of investigations 134 investigation areas were selected inside 61 bedrock blocks and classified to four priority classes, the three first of which were redommended for further investigations. Geological criteries used in classification indicated clear differences between the classes one and three, however all classified areas are situated in large rather homogenous bedrock blocks and more exact three dimensional suitability errors may not be observed until deep bore holes have been made
Employing Eigenvalue Ratios to Generate Prior Fracture-like Features for Stochastic Hydrogeophysical Characterization of a Fractured Aquifer System

Science.gov (United States)

Brewster, J.; Oware, E. K.

2017-12-01

Groundwater hosted in fractured rocks constitutes almost 65% of the principal aquifers in the US. The exploitation and contaminant management of fractured aquifers require fracture flow and transport modeling, which in turn requires a detailed understanding of the structure of the aquifer. The widely used equivalent porous medium approach to modeling fractured aquifer systems is inadequate to accurately predict fracture transport processes due to the averaging of the sharp lithological contrast between the matrix and the fractures. The potential of geophysical imaging (GI) to estimate spatially continuous subsurface profiles in a minimally invasive fashion is well proven. Conventional deterministic GI strategies, however, produce geologically unrealistic, smoothed-out results due to commonly enforced smoothing constraints. Stochastic GI of fractured aquifers is becoming increasing appealing due to its ability to recover realistic fracture features while providing multiple likely realizations that enable uncertainty assessment. Generating prior spatial features consistent with the expected target structures is crucial in stochastic imaging. We propose to utilize eigenvalue ratios to resolve the elongated fracture features expected in a fractured aquifer system. Eigenvalues capture the major and minor directions of variability in a region, which can be employed to evaluate shape descriptors, such as eccentricity (elongation) and orientation of features in the region. Eccentricity ranges from zero to one, representing a circularly sharped to a line feature, respectively. Here, we apply eigenvalue ratios to define a joint objective parameter consisting of eccentricity (shape) and direction terms to guide the generation of prior fracture-like features in some predefined principal directions for stochastic GI. Preliminary unconditional, synthetic experiments reveal the potential of the algorithm to simulate prior fracture-like features. We illustrate the strategy with a
Formation evaluation of fractured basement, Cambay Basin, India

International Nuclear Information System (INIS)

Gupta, Saurabh Datta; Farooqui, M Y; Chatterjee, Rima

2012-01-01

Unconventional reservoirs such as fractured basalts, shale gas and tight sand are currently playing an important role in producing a significant amount of hydrocarbon. The Deccan Trap basaltic rocks form the basement of the Cambay Basin, India, and hold commercially producible hydrocarbon. In this study two wells drilled through fractured basalts are chosen for evaluating the lithology, porosity and oil saturation of the reservoir sections. Well logs, such as gamma ray, high resolution resistivity, litho density, compensated neutron and elemental capture spectroscopy, have been used in cross-plotting techniques for lithology and mineral identification. Formation micro imagery log data have been analysed to quantify the fractures and porosity in the fractured reservoirs for a well in the south Ahmedabad block of the Cambay Basin. The results of the analysis of two wells are presented and discussed and they are found to be in good agreement with geological and production data. (paper)
The Influence of Fractures on Radionuclide Transport in Granite Formations

International Nuclear Information System (INIS)

Guarracino, Luis; Quintana, Fernando; Bevilacqua, Arturo

2003-01-01

Simulation of radionuclide transport in fractured hard rocks is of interest to many research areas like geological disposal of high-level nuclear wastes.The objective of this study is to present a numerical simulation of water flow and radionuclide transport near a hypothetical repository in deep geological formations.The water flow is assumed to obey the highly nonlinear Richards' equation, which is approximated using a finite element method for the spatial discretization combined with a third order accurate Crank-Nicholson scheme in time.A Picard iteration scheme is used to treat the non-linear terms of the equation.Contaminant transport is described by the advection-diffusion-reaction equation, assuming linear adsorption and first order decay.This equation is solved using a Sub Grid Scale algorithm.Illustrative examples showing the influence of fractures in the contaminant process for different radioisotopes are presented
Toward physical aspects affecting a possible leakage of geologically stored CO₂ into the shallow subsurface

DEFF Research Database (Denmark)

Singh, Ashok; Delfs, Jens Olaf; Görke, Uwe Jens

2014-01-01

In geological formations, migration of CO2 plume is very complex and irregular. To make CO2 capture and storage technology feasible, it is important to quantify CO2 amount associated with possible leakage through natural occurring faults and fractures in geologic medium. Present work examines the...
Analysis of fracture patterns and local stress field variations in fractured reservoirs

Science.gov (United States)

Deckert, Hagen; Drews, Michael; Fremgen, Dominik; Wellmann, J. Florian

2010-05-01

A meaningful qualitative evaluation of permeabilities in fractured reservoirs in geothermal or hydrocarbon industry requires the spatial description of the existing discontinuity pattern within the area of interest and an analysis how these fractures might behave under given stress fields. This combined information can then be used for better estimating preferred fluid pathway directions within the reservoir, which is of particular interest for defining potential drilling sites. A description of the spatial fracture pattern mainly includes the orientation of rock discontinuities, spacing relationships between single fractures and their lateral extent. We have examined and quantified fracture patterns in several outcrops of granite at the Costa Brava, Spain, and in the Black Forest, Germany, for describing reservoir characteristics. For our analysis of fracture patterns we have used photogrammetric methods to create high-resolution georeferenced digital 3D images of outcrop walls. The advantage of this approach, compared to conventional methods for fracture analysis, is that it provides a better 3D description of the fracture geometry as the entity of position, extent and orientation of single fractures with respect to their surrounding neighbors is conserved. Hence for instance, the method allows generating fracture density maps, which can be used for a better description of the spatial distribution of discontinuities in a given outcrop. Using photogrammetric techniques also has the advantage to acquire very large data sets providing statistically sound results. To assess whether the recorded discontinuities might act as fluid pathways information on the stress field is needed. A 3D model of the regional tectonic structure was created and the geometry of the faults was put into a mechanical 3D Boundary Element (BE) Model. The model takes into account the elastic material properties of the geological units and the orientation of single fault segments. The
Joint seismic, hydrogeological, and geomechanical investigations of a fracture zone in the Grimsel Rock Laboratory, Switzerland

International Nuclear Information System (INIS)

Majer, E.L.; Myer, L.R.; Peterson, J.E. Jr.; Karasaki, K.; Long, J.C.S.; Martel, S.J.; Bluemling, P.; Vomvoris, S.

1990-06-01

This report is one of a series documenting the results of the Nagra-DOE Cooperative (NDC-I) research program in which the cooperating scientists explore the geological, geophysical, hydrological, geochemical, and structural effects anticipated from the use of a rock mass as a geologic repository for nuclear waste. From 1987 to 1989 the United States Department of Energy (DOE) and the Swiss Cooperative for the Storage of Nuclear Waste (Nagra) participated in an agreement to carryout experiments for understanding the effect of fractures in the storage and disposal of nuclear waste. As part of this joint work field and laboratory experiments were conducted at a controlled site in the Nagra underground Grimsel test site in Switzerland. The primary goal of these experiments in this fractured granite was to determine the fundamental nature of the propagation of seismic waves in fractured media, and to relate the seismological parameters to the hydrological parameters. The work is ultimately aimed at the characterization and monitoring of subsurface sites for the storage of nuclear waste. The seismic experiments utilizes high frequency (1000 to 10,000 Hertz) signals in a cross-hole configuration at scales of several tens of meters. Two-, three-, and four-sided tomographic images of the fractures and geologic structure were produced from over 60,000 raypaths through a 10 by 21 meter region bounded by two nearly horizontal boreholes and two tunnels. Intersecting this region was a dominant fracture zone which was the target of the investigations. In addition to these controlled seismic imaging experiments, laboratory work using core from this region were studied for the relation between fracture content, saturation, and seismic velocity and attenuation. In-situ geomechanical and hydrologic tests were carried out to determine the mechanical stiffness and conductivity of the fractures. 20 refs., 90 figs., 6 tabs
Geological and Seismic Data Mining For The Development of An Interpretation System Within The Alptransit Project

Science.gov (United States)

Klose, C. D.; Giese, R.; Löw, S.; Borm, G.

Especially for deep underground excavations, the prediction of the locations of small- scale hazardous geotechnical structures is nearly impossible when exploration is re- stricted to surface based methods. Hence, for the AlpTransit base tunnels, exploration ahead has become an essential component of the excavation plan. The project de- scribed in this talk aims at improving the technology for the geological interpretation of reflection seismic data. The discovered geological-seismic relations will be used to develop an interpretation system based on artificial intelligence to predict hazardous geotechnical structures of the advancing tunnel face. This talk gives, at first, an overview about the data mining of geological and seismic properties of metamorphic rocks within the Penninic gneiss zone in Southern Switzer- land. The data results from measurements of a specific geophysical prediction system developed by the GFZ Potsdam, Germany, along the 2600 m long and 1400 m deep Faido access tunnel. The goal is to find those seismic features (i.e. compression and shear wave velocities, velocity ratios and velocity gradients) which show a significant relation to geological properties (i.e. fracturing and fabric features). The seismic properties were acquired from different tomograms, whereas the geolog- ical features derive from tunnel face maps. The features are statistically compared with the seismic rock properties taking into account the different methods used for the tunnel excavation (TBM and Drill/Blast). Fracturing and the mica content stay in a positive relation to the velocity values. Both, P- and S-wave velocities near the tunnel surface describe the petrology better, whereas in the interior of the rock mass they correlate to natural micro- and macro-scopic fractures surrounding tectonites, i.e. cataclasites. The latter lie outside of the excavation damage zone and the tunnel loos- ening zone. The shear wave velocities are better indicators for rock
Research on comprehensive gas permeability improvement technology by hydraulic fracturing and slotting in coal seam with complex geological conditions and low permeability%复杂地质低渗煤层水力压裂-割缝综合瓦斯增透技术研究

Institute of Scientific and Technical Information of China (English)

贾同千; 饶孜; 何庆兵; 宋润权; 白鑫

2017-01-01

Aiming at the problem of gas drainage in the coal seam with complex geological conditions and low permeability in Baijiao Coal Mine,the hydraulic fracturing technology was applied to carry out the regional gas permeability improvement,and its application effect was analyzed according to the situation of field gas drainage.Aiming at the blind area of regional gas permeability improvement by hydraulic fracturing,the technical measure of localized gas permeability improvement by hydraulic slotting was put forward,then the comprehensive gas permeability improvement technology by hydraulic fracturing and slotting in coal seam with complex geological conditions and low permeability was formed,and the field verification was conducted.The results showed that the average pure flow rate of gas drainage for three fracturing boreholes in the hydraulic fracturing zone increased by 15.8 times than that of regular single borehole gas drainage in 238 floor laneway,and the gas drainage concentration increased by 4％.The pure flow rate of gas drainage in the fractured area increased by 2.1 times than that of the comparison zone,but there existed the blind area by the regional measures of hydraulic fracturing due to the restriction of geological conditions such as fault and coal seam hardness.The gas concentration of drainage borehole in the hydraulic slotting permeability improvement zone increased by 4.9 times on the average,and the pure flow rate of gas increased by 3.3 times on the average.It has strong adaptability to different geological conditions,but the influence range of slotting is small,and the drainage time is short.The comprehensive gas permeability improvement technology by hydraulic fracturing and slotting in coal seam with complex geological conditions and low permeability integrates the advantages of hydraulic fracturing and slotting,and it has strong adaptability to coal seam with complex geological conditions,which improves the gas control level greatly.The field
Venus: Preliminary geologic mapping of northern Atla Regio

Science.gov (United States)

Nikishin, A. M.; Burba, G. A.

1992-01-01

A preliminary geologic map of C1 sheet 15N197 was compiled according to Magellan data. Northern Atla Regio is dominantly a volcanic plain with numerous volcanic features: radar-bright and -dark flows and spots, shield volcanos, volcanic domes and hills with varied morphology, and coronalike constructions. Tesserae are the oldest terrains semiflooded by plain materials. There are many lineated terrains on this territory. They are interpreted as old, partly buried ridge belts. Lineated terrains have intermediate age between young plains and old tesserae. Ozza Mons and Sapas Mons are the high shield volcanos. The prominent structure of northern Atla Regio is Ganis Chasma rift. The rift dissected the volcanic plain and evolved nearly contemporaneously with Ozza Mons shield volcano. Ganis Chasma rift valley is highly fractured and bounded by fault scarps. There are a few relatively young volcanic features in the rift valley. The rift originated due to 5-10 percent crustal extension and crustal subsidence according to analysis of fracturing and rift valley geometry. Ganis Chasma is characterized by rift shoulder uplifts. Geological structures of Alta Regio and Beta Regio are very similar as assumed earlier.
Assessing the fracture strength of geological and related materials via an atomistically based J-integral

Science.gov (United States)

Jones, R. E.; Criscenti, L. J.; Rimsza, J.

2016-12-01

Predicting fracture initiation and propagation in low-permeability geomaterials is a critical yet un- solved problem crucial to assessing shale caprocks at carbon dioxide sequestration sites, and controlling fracturing for gas and oil extraction. Experiments indicate that chemical reactions at fluid-geomaterial interfaces play a major role in subcritical crack growth by weakening the material and altering crack nu- cleation and growth rates. Engineering the subsurface fracture environment, however, has been hindered by a lack of understanding of the mechanisms relating chemical environment to mechanical outcome, and a lack of capability directly linking atomistic insight to macroscale observables. We have developed a fundamental atomic-level understanding of the chemical-mechanical mecha- nisms that control subcritical cracks through coarse-graining data from reactive molecular simulations. Previous studies of fracture at the atomic level have typically been limited to producing stress-strain curves, quantifying either the system-level stress or energy at which fracture propagation occurs. As such, these curves are neither characteristic of nor insightful regarding fracture features local to the crack tip. In contrast, configurational forces, such as the J-integral, are specific to the crack in that they measure the energy available to move the crack and truly quantify fracture resistance. By development and use of field estimators consistent with the continuum conservation properties we are able to connect the data produced by atomistic simulation to the continuum-level theory of fracture mechanics and thus inform engineering decisions. In order to trust this connection we have performed theoretical consistency tests and validation with experimental data. Although we have targeted geomaterials, this capability can have direct impact on other unsolved technological problems such as predicting the corrosion and embrittlement of metals and ceramics. Sandia National
Statistical methodology for discrete fracture model - including fracture size, orientation uncertainty together with intensity uncertainty and variability

International Nuclear Information System (INIS)

Darcel, C.; Davy, P.; Le Goc, R.; Dreuzy, J.R. de; Bour, O.

2009-11-01

Investigations led for several years at Laxemar and Forsmark reveal the large heterogeneity of geological formations and associated fracturing. This project aims at reinforcing the statistical DFN modeling framework adapted to a site scale. This leads therefore to develop quantitative methods of characterization adapted to the nature of fracturing and data availability. We start with the hypothesis that the maximum likelihood DFN model is a power-law model with a density term depending on orientations. This is supported both by literature and specifically here by former analyses of the SKB data. This assumption is nevertheless thoroughly tested by analyzing the fracture trace and lineament maps. Fracture traces range roughly between 0.5 m and 10 m - i e the usual extension of the sample outcrops. Between the raw data and final data used to compute the fracture size distribution from which the size distribution model will arise, several steps are necessary, in order to correct data from finite-size, topographical and sampling effects. More precisely, a particular attention is paid to fracture segmentation status and fracture linkage consistent with the DFN model expected. The fracture scaling trend observed over both sites displays finally a shape parameter k t close to 1.2 with a density term (α 2d ) between 1.4 and 1.8. Only two outcrops clearly display a different trend with k t close to 3 and a density term (α 2d ) between 2 and 3.5. The fracture lineaments spread over the range between 100 meters and a few kilometers. When compared with fracture trace maps, these datasets are already interpreted and the linkage process developed previously has not to be done. Except for the subregional lineament map from Forsmark, lineaments display a clear power-law trend with a shape parameter k t equal to 3 and a density term between 2 and 4.5. The apparent variation in scaling exponent, from the outcrop scale (k t = 1.2) on one side, to the lineament scale (k t = 2) on
Modeling of flow in faulted and fractured media

Energy Technology Data Exchange (ETDEWEB)

Oeian, Erlend

2004-03-01

The work on this thesis has been done as part of a collaborative and inter disciplinary effort to improve the understanding of oil recovery mechanisms in fractured reservoirs. This project has been organized as a Strategic University Program (SUP) at the University of Bergen, Norway. The complex geometries of fractured reservoirs combined with flow of several fluid phases lead to difficult mathematical and numerical problems. In an effort to try to decrease the gap between the geological description and numerical modeling capabilities, new techniques are required. Thus, the main objective has been to improve the ATHENA flow simulator and utilize it within a fault modeling context. Specifically, an implicit treatment of the advection dominated mass transport equations within a domain decomposition based local grid refinement framework has been implemented. Since large computational tasks may arise, the implicit formulation has also been included in a parallel version of the code. Within the current limits of the simulator, appropriate up scaling techniques has also been considered. Part I of this thesis includes background material covering the basic geology of fractured porous media, the mathematical model behind the in-house flow simulator ATHENA and the additions implemented to approach simulation of flow through fractured and faulted porous media. In Part II, a set of research papers stemming from Part I is presented. A brief outline of the thesis follows below. In Chapt. 1 important aspects of the geological description and physical parameters of fractured and faulted porous media is presented. Based on this the scope of this thesis is specified having numerical issues and consequences in mind. Then, in Chapt. 2, the mathematical model and discretizations in the flow simulator is given followed by the derivation of the implicit mass transport formulation. In order to be fairly self-contained, most of the papers in Part II also includes the mathematical model
Modeling of flow in faulted and fractured media

Energy Technology Data Exchange (ETDEWEB)

Oeian, Erlend

2004-03-01

The work on this thesis has been done as part of a collaborative and inter disciplinary effort to improve the understanding of oil recovery mechanisms in fractured reservoirs. This project has been organized as a Strategic University Program (SUP) at the University of Bergen, Norway. The complex geometries of fractured reservoirs combined with flow of several fluid phases lead to difficult mathematical and numerical problems. In an effort to try to decrease the gap between the geological description and numerical modeling capabilities, new techniques are required. Thus, the main objective has been to improve the ATHENA flow simulator and utilize it within a fault modeling context. Specifically, an implicit treatment of the advection dominated mass transport equations within a domain decomposition based local grid refinement framework has been implemented. Since large computational tasks may arise, the implicit formulation has also been included in a parallel version of the code. Within the current limits of the simulator, appropriate up scaling techniques has also been considered. Part I of this thesis includes background material covering the basic geology of fractured porous media, the mathematical model behind the in-house flow simulator ATHENA and the additions implemented to approach simulation of flow through fractured and faulted porous media. In Part II, a set of research papers stemming from Part I is presented. A brief outline of the thesis follows below. In Chapt. 1 important aspects of the geological description and physical parameters of fractured and faulted porous media is presented. Based on this the scope of this thesis is specified having numerical issues and consequences in mind. Then, in Chapt. 2, the mathematical model and discretizations in the flow simulator is given followed by the derivation of the implicit mass transport formulation. In order to be fairly self-contained, most of the papers in Part II also includes the mathematical model
Fracture characterization and discrimination criteria for karst and tectonic fractures in the Ellenburger Group, West Texas: Implications for reservoir and exploration models

Energy Technology Data Exchange (ETDEWEB)

Hoak, T.E. [Science Applications International Corp., Germantown, MD (United States)]|[Kestrel Geoscience, Littleton, CO (United States); Sundberg, K.R. [Phillips Petroleum Co., Bartlesville, OK (United States); Deyhim, P. [Oklahoma State Univ., Stillwater, OK (United States); Ortoleva, P. [Indiana Univ., Bloomington, IN (United States). Lab. for Computational Geodynamics

1998-12-31

In the Ellenburger Group fractured dolomite reservoirs of West Texas, it is extremely difficult to distinguish between multiple phases of karst-related fracturing, modifications to the karst system during burial, and overprinting tectonic fractures. From the analyses of drill core, the authors developed criteria to distinguish between karst and tectonic fractures. In addition, they have applied these criteria within the context of a detailed diagenetic cement history that allows them to further refine the fracture genesis and chronology. In these analyses, the authors evaluated the relationships between fracture intensity, morphologic attributes, host lithology, fracture cement, and oil-staining. From this analysis, they have been able to characterize variations in Ellenburger tectonic fracture intensity by separating these fractures from karst-related features. In general, the majority of fracturing in the Ellenburger is caused by karst-related fracturing although a considerable percentage is caused by tectonism. These findings underscore the importance of considering the complete geologic evolution of a karst reservoir during exploration and field development programs. The authors have been able to more precisely define the spatial significance of the fracture data sets by use of oriented core from Andector Field. They have also demonstrated the importance of these results for exploration and reservoir development programs in West Texas, and the potential to extrapolate these results around the globe. Given the historic interest in the large hydrocarbon reserves in West Texas carbonate reservoirs, results of this study will have tremendous implications for exploration and production strategies targeting vuggy, fractured carbonate systems not only in West Texas, but throughout the globe.
Self-sealing of fractures in argillaceous formations - Evidence, mechanisms and implications for performance assesment (an NEA Clay Club project)

International Nuclear Information System (INIS)

Bock, H.; Dehandschutter, B.; Martin, C.D.; Mazurek, M.; Haller, A. de; Skoczylas, F.; Davy, C.

2010-01-01

Document available in extended abstract form only. After some earlier attempts dating back to the year 1999, the Self-Sealing Project of the Clay Club of the NEA/OECD was re-launched in 2007 and recently completed with the publication of NEA monograph No. 6184 (Bock et al., 2010). The project aimed at providing an overview and synthesis of the current understanding of, and conceptual approaches to, the processes that lead to self-sealing of natural and man-induced fractures in argillaceous formations at typical repository depths. The term 'self-sealing' relates to a phenomenon that fractured argillaceous formations tend to become, with the passage of time, less conductive to groundwater and finally hydraulically insignificant. It directly addresses the long-term functionality of the host rock as a migration barrier to radio-nuclides and it is often considered as one of the decisive factors favouring the choice of argillaceous formations as host rocks for deep disposals. In its outcome the project has significantly consolidated the evidence on self-sealing in argillaceous formations. It reconfirmed that self-sealing is a common phenomenon in a wide variety of argillaceous formations which are currently considered in context with deep geological repositories; from plastic clays (Boom Clay in the HADES URF) to moderately indurated clays (Opalinus Clay at Mont Terri and Callovo- Oxfordian argillites at the Meuse-Haute Marne URL). One of the most compelling evidence stems from the fact that self-sealing is observed over a large spread of scales in terms of length and time: At the millimetre to metre scale in laboratory testing, at the repository scale (10 m to 100 m range) in URL field tests and at the kilometre scale in geologic and geotechnical analogues such as traffic tunnels and hydrocarbon reservoirs. Over geological time scales, it is, for example, evidenced in the existence of hydraulically and geochemically inactive geological faults, in the existence
Overview of geologic and geohydrologic conditions at the Finnsjoen site and its surroundings

International Nuclear Information System (INIS)

Ahlbom, K.; Tiren, S.

1991-01-01

The geologic and tectonic conditions of the Finnsjoen site and its surroundings have been studied on several scales ranging from regional to site scale. The Finnsjoen study is situated within a 50 square km shear lens. This lens is a part of a regional, c.20-30 km wide, WNW trending shear belt that was developed 1600-1800 million years ago. The final repository for reactor waste at Forsmark is also situated within this shear belt. The Finnsjoen Rock Block, bounded by regional and semi-regional fracture zones, constitute the main part of the Finnsjoen site. The size of the block is about 6 square km. A northeasterly trending fracture zone, Zone 1, divides this block into two lower order blocks, the northern and the southern block. In general, interpreted fracture zones, as well as the rock mass in general, are far better known in the northern Finnsjoen block compared to the southern block. This is due to extensive and detailed investigations of a gently dipping fracture zone, Zone 2, in the northern block. A tectonic model including 14 fracture zones is suggested for the Finnsjoen site and its surroundings. These zones have mainly been interpreted from lineament maps and to some extent from borehole measurements. The lack of borehole data implies that many of interpreted fracture zones, especially in the southern block outside the Finnsjoen site, should be regarded as tentative. The good general knowledge of the geologic and geohydrologic conditions in the northern Finnsjoen block, and possible stagnant groundwater conditions below Zone 2, makes the northern block the most suitable location for the generic repository at the Finnsjoen site. (authors)
Wave Propagation in Jointed Geologic Media

Energy Technology Data Exchange (ETDEWEB)

Antoun, T

2009-12-17

Predictive modeling capabilities for wave propagation in a jointed geologic media remain a modern day scientific frontier. In part this is due to a lack of comprehensive understanding of the complex physical processes associated with the transient response of geologic material, and in part it is due to numerical challenges that prohibit accurate representation of the heterogeneities that influence the material response. Constitutive models whose properties are determined from laboratory experiments on intact samples have been shown to over-predict the free field environment in large scale field experiments. Current methodologies for deriving in situ properties from laboratory measured properties are based on empirical equations derived for static geomechanical applications involving loads of lower intensity and much longer durations than those encountered in applications of interest involving wave propagation. These methodologies are not validated for dynamic applications, and they do not account for anisotropic behavior stemming from direcitonal effects associated with the orientation of joint sets in realistic geologies. Recent advances in modeling capabilities coupled with modern high performance computing platforms enable physics-based simulations of jointed geologic media with unprecedented details, offering a prospect for significant advances in the state of the art. This report provides a brief overview of these modern computational approaches, discusses their advantages and limitations, and attempts to formulate an integrated framework leading to the development of predictive modeling capabilities for wave propagation in jointed and fractured geologic materials.
Three dimensional fracture aperture and porosity distribution using computerized tomography

Science.gov (United States)

Wenning, Q.; Madonna, C.; Joss, L.; Pini, R.

2017-12-01

A wide range of geologic processes and geo-engineered applications are governed by coupled hydromechanical properties in the subsurface. In geothermal energy reservoirs, quantifying the rate of heat transfer is directly linked with the transport properties of fractures, underscoring the importance of fracture aperture characterization for achieving optimal heat production. In this context, coupled core-flooding experiments with non-invasive imaging techniques (e.g., X-Ray Computed Tomography - X-Ray CT) provide a powerful method to make observations of these properties under representative geologic conditions. This study focuses on quantifying fracture aperture distribution in a fractured westerly granite core by using a recently developed calibration-free method [Huo et al., 2016]. Porosity is also estimated with the X-ray saturation technique using helium and krypton gases as saturating fluids, chosen for their high transmissibility and high CT contrast [e.g., Vega et al., 2014]. The westerly granite sample (diameter: 5 cm, length: 10 cm) with a single through-going rough-walled fracture was mounted in a high-pressure aluminum core-holder and placed inside a medical CT scanner for imaging. During scanning the pore fluid pressure was undrained and constant, and the confining pressure was regulated to have the desired effective pressure (0.5, 5, 7 and 10 MPa) under loading and unloading conditions. 3D reconstructions of the sample have been prepared in terms of fracture aperture and porosity at a maximum resolution of (0.24×0.24×1) mm3. Fracture aperture maps obtained independently using helium and krypton for the whole core depict a similar heterogeneous aperture field, which is also dependent on confining pressure. Estimates of the average hydraulic aperture from CT scans are in quantitative agreement with results from fluid flow experiments. However, the latter lack of the level of observational detail achieved through imaging, which further evidence the
Geological 3D model of the investigation niche in ONKALO, Olkiluoto, southwestern Finland

Energy Technology Data Exchange (ETDEWEB)

Koittola, N.

2014-07-15

The main goal of this Master of Science Thesis was to create a geological 3D-model of the investigation niche 3 and its surroundings. The model were created for the needs of the rock mechanical back analysis. This study is a part of Posiva's regional studies for characterization of the bedrock. Totally 4 models were created: lithological model, foliation model, fracture model, and physical rock property model. Besides the modeling, there was also made a study of the migmatite structures in the niche. Used geological and geophysical methods were drill core loggings, tunnel mapping, ground penetration radar, mise-a-la-masse and drill hole geophysics. Four rock types exist at the niche area: veined gneiss, pegmatite granite, diatexitic gneiss and quartz gneiss. The lithological units were modeled primary with the drill core loggings, tunnel mapping and ground penetrating radar. The major lithological units followed the main foliation direction (south dipping). So the continuations were fairly easy to model in the walls and roof, where the data was lacking. Foliation and fractures were modeled as discs, with mid-points at the measurement points of the structure. There were two main foliation directions 164/46 and 62/39. Fractures were more scattered but three fracture sets can be separated: 156/34, 270/85 and 342/83. The first set is mainly from the drill core loggings, second and third from tunnel mapping. Used methods in foliation model were drill core loggings, tunnel mapping and drill hole geophysics. In fracture model used data was from drill core loggings, tunnel mapping, mise-a-la-masse measurements and drill core geophysic. Four anomalous zones were detected with the drill hole geophysics. Three of these zones were associated with intensely fractured zones and one was connected to exceptionally high mica content in the gneiss. Rocks of Olkiluoto are divided into gneisses and magmatic rocks in the geological mapping. Actually almost all Olkiluoto

Geological 3D model of the investigation niche in ONKALO, Olkiluoto, southwestern Finland

International Nuclear Information System (INIS)

Koittola, N.

2014-07-01

The main goal of this Master of Science Thesis was to create a geological 3D-model of the investigation niche 3 and its surroundings. The model were created for the needs of the rock mechanical back analysis. This study is a part of Posiva's regional studies for characterization of the bedrock. Totally 4 models were created: lithological model, foliation model, fracture model, and physical rock property model. Besides the modeling, there was also made a study of the migmatite structures in the niche. Used geological and geophysical methods were drill core loggings, tunnel mapping, ground penetration radar, mise-a-la-masse and drill hole geophysics. Four rock types exist at the niche area: veined gneiss, pegmatite granite, diatexitic gneiss and quartz gneiss. The lithological units were modeled primary with the drill core loggings, tunnel mapping and ground penetrating radar. The major lithological units followed the main foliation direction (south dipping). So the continuations were fairly easy to model in the walls and roof, where the data was lacking. Foliation and fractures were modeled as discs, with mid-points at the measurement points of the structure. There were two main foliation directions 164/46 and 62/39. Fractures were more scattered but three fracture sets can be separated: 156/34, 270/85 and 342/83. The first set is mainly from the drill core loggings, second and third from tunnel mapping. Used methods in foliation model were drill core loggings, tunnel mapping and drill hole geophysics. In fracture model used data was from drill core loggings, tunnel mapping, mise-a-la-masse measurements and drill core geophysic. Four anomalous zones were detected with the drill hole geophysics. Three of these zones were associated with intensely fractured zones and one was connected to exceptionally high mica content in the gneiss. Rocks of Olkiluoto are divided into gneisses and magmatic rocks in the geological mapping. Actually almost all Olkiluoto's rocks are
Integration of 3D geological modeling and gravity surveys for geothermal prospection in an Alpine region

Science.gov (United States)

Guglielmetti, L.; Comina, C.; Abdelfettah, Y.; Schill, E.; Mandrone, G.

2013-11-01

Thermal sources are common manifestations of geothermal energy resources in Alpine regions. The up-flow of the fluid is well-known to be often linked to cross-cutting fault zones providing a significant volume of fractures. Since conventional exploration methods are challenging in such areas of high topography and complicated logistics, 3D geological modeling based on structural investigation becomes a useful tool for assessing the overall geology of the investigated sites. Geological modeling alone is, however, less effective if not integrated with deep subsurface investigations that could provide a first order information on geological boundaries and an imaging of geological structures. With this aim, in the present paper the combined use of 3D geological modeling and gravity surveys for geothermal prospection of a hydrothermal area in the western Alps was carried out on two sites located in the Argentera Massif (NW Italy). The geothermal activity of the area is revealed by thermal anomalies with surface evidences, such as hot springs, at temperatures up to 70 °C. Integration of gravity measurements and 3D modeling investigates the potential of this approach in the context of geothermal exploration in Alpine regions where a very complex geological and structural setting is expected. The approach used in the present work is based on the comparison between the observed gravity and the gravity effect of the 3D geological models, in order to enhance local effects related to the geothermal system. It is shown that a correct integration of 3D modeling and detailed geophysical survey could allow a better characterization of geological structures involved in geothermal fluids circulation. Particularly, gravity inversions have successfully delineated the continuity in depth of low density structures, such as faults and fractured bands observed at the surface, and have been of great help in improving the overall geological model.
Study on flow and mass transport through fractured sedimentary rocks (2)

International Nuclear Information System (INIS)

Shimo, Michito; Kumamoto, Sou; Karasaki, Kenzi; Sato, Hisashi; Sawada, Atsushi

2009-03-01

It is important for safety assessment of HLW geological disposal to understand hydro-geological conditions at the investigation area, and to evaluate groundwater flow and mass transport model and parameters, at each investigation phase. Traditionally, for Neogene sedimentary rock, the grain spacing of sediments has been considered as the dominant migration path. However, fractures of sedimentary rock could act as dominant paths, although they were soft sedimentary rocks. In this study, as part of developing groundwater flow and mass transport evaluation methodologies of such a fractured sedimentary rock' distributed area, we conducted two different scale of studies; 1) core rock sample scale and 2) several kilometer scale. For the core rock sample scale, some of laboratory hydraulic and tracer experiments have conducted using the rock cores with tailored parallel fracture, obtained at pilot borehole drilled in the vicinity of ventilation shaft. From the test results, hydraulic conductivity, diffusion coefficient, transport aperture, dispersion length and etc. was evaluated. Based on these test results, the influence of these parameters onto mass transport behavior of fractures sedimentary rocks was examined. For larger scale, such as several kilometer scale, the regional scale groundwater flow was examined using temperature data observed along the boreholes at Horonobe site. The results show that the low permeable zone between the boreholes might be estimated. (author)
Challenges and Solutions for the Integration of Structural and Hydrogeological Understanding of Fracture Systems - Insights from the Olkiluoto Site, Finland

Science.gov (United States)

Hartley, L. J.; Aaltonen, I.; Baxter, S. J.; Cottrell, M.; Fox, A. L.; Hoek, J.; Koskinen, L.; Mattila, J.; Mosley, K.; Selroos, J. O.; Suikkanen, J.; Vanhanarkaus, O.; Williams, T. R. N.

2017-12-01

A field site at Olkiluoto in SW Finland has undergone extensive investigations as a location for a deep geological repository for spent nuclear fuel, which is expected to become operational in the early 2020s. Characterisation data comes from 58 deep cored drillholes, a wide variety of geophysical investigations, many outcrops, kilometres of underground mapping and testing in the ONKALO research facility, and groundwater pressure monitoring and sampling in both deep and shallow holes. A primary focus is on the properties of natural fractures and brittle fault zones in the low permeability crystalline rocks at Olkiluoto; an understanding of the flow and transport processes in these features are an essential part of assessing long-term safety of the repository. This presentation will illustrate how different types of source data and cross-disciplinary interpretations are integrated to develop conceptual and numerical models of the fracture system. A model of the brittle fault zones developed from geological and geophysical data provides the hydrostructural backbone controlling the most intense fracturing and dynamic conduits for fluids. Models of ductile deformation and lithology form a tectonic framework for the description of fracture heterogeneity in the background rock, revealing correlations between the intensity and orientation of fractures with geological and spatial properties. The sizes of brittle features are found to be best defined on two scales relating to individual fractures and zones. Inferred fracture-specific from flow logging are correlated with fracture geometric and mechanical properties along with in situ stress measurements to create a hydromechanical description of fracture hydraulic properties. The insights and understandings gained from these efforts help define a discrete fracture network (DFN) model for the Olkiluoto site, with hydrogeological characteristics consistent with monitoring data of hydraulic heads and their disturbances to
On the theory of transport in fractured media for the safety analysis of a nuclear waste repository

International Nuclear Information System (INIS)

Mukhopadhyay, N.C.

1982-10-01

This paper aims at developing a systematic theory of the role of fractures in the transport of radionuclides in the fractured rocks by groundwater, from the nuclear waste repository to be built in the deep geological formations, to the biosphere. Fractures are grouped into four 'irreducible' types: joints, nodes, shear zones and fracture zones, and their physical characteristics, having bearings on radionuclide transport, are expressed in mathematical terms. The question of radioactivity retention is then carefully studied for various fracture types, using idealized geometries to mimic natural forms. Fundamental transport equations are derived for the fracture-pore complex, taking into consideration the special physical characteristics of fractures and the effects of sorption therein
Compilation of data used for the analysis of the geological and hydrogeological DFN models. Site descriptive modelling SDM-Site Laxemar

International Nuclear Information System (INIS)

Hermanson, Jan; Fox, Aaron; Oehman, Johan; Rhen, Ingvar

2008-08-01

This report provides an overview and compilation of the various data that constitutes the basis for construction of the geological and hydrogeological discrete feature network (DFN) models as part of model version SDM-Site Laxemar. This includes a review of fracture data in boreholes and in outcrop. Furthermore, the basis for the construction of lineament maps is given as well as a review of the hydraulic test data from cored and percussion-drilled boreholes. An emphasis is put on graphical representation of borehole logs in the form of composites of geological, hydrogeological and even hydrogeochemical data in the case of cored boreholes. One major contribution is a compilation of characteristics of minor local deformation zones (MDZs) identified in cored boreholes. Basic orientation data and fracture intensity data are presented as a function of depth for individual boreholes. The coupling between hydrogeological data and geological data is further refined in plots of Posiva flow log (PFL) data vs. geological single hole interpretation data
Fractured Reservoir Simulation: a Challenging and Rewarding Issue Simulation des réservoirs fracturés : un défi et un enjeu

Directory of Open Access Journals (Sweden)

Bourbiaux B.

2010-03-01

Full Text Available The recent years have seen a growing awareness of the role played by fractures in petroleum reservoirs production and recovery. Hence, much effort was devoted to the diagnosis of fracture presence and impact on production. However, turning that diagnosis into field development decisions goes through reservoir simulation. This paper addresses some of the specificities of fractured reservoirs that make that their simulation is both challenging and rewarding. Indeed, the integration of fractures into a flow simulation model is not straightforward because of the existing gap between the geological fault/fracture network and the fingerprint of that network on often-complex recovery mechanisms. Considering that fractures may impede or enhance production, fractured reservoir simulation may be seen as a technical challenge with potentially-high reward. This paper underlines that specific framework as an introduction to two technical articles dedicated to dual-porosity reservoir simulation. Although it constitutes another major aspect of any fractured reservoir study, the geological characterization of fractures is not discussed herein, but only evoked because of more and more integration of static and dynamic aspects. Au cours des années récentes, la prise de conscience du rôle des fractures sur la production et la récupération des champs est devenue de plus en plus forte au sein de la communauté pétrolière. Aussi beaucoup d’efforts ont-ils été consacrés à la détection des fractures et à l’analyse de leur impact sur la production. Toutefois, la prise en considération de ces observations dans les choix de développement des champs passe par la simulation de réservoir. Cet article traite des spécificités propres aux réservoirs fracturés et qui font de leur simulation à la fois un défi et un enjeu. En effet, l’intégration des fractures dans un modèle de simulation des écoulements n’est pas immédiate en raison du difficile
The measurement of density distribution of bentonite buffer extruded into fractures

International Nuclear Information System (INIS)

Matsumoto, Kazuhiro; Tanai, Kenji

2008-01-01

For the geological disposal of the high-level radioactive waste, it is important to develop the model to evaluate the long-term stability of the engineered barrier system. The increase in the reliability of the evaluation model may reduce the uncertainty of the safety assessment. In this study, the density distribution of the bentonite buffer extruded into the artificial fractures was measured by using a X-ray CT scanner to promote understanding of the extrusion phenomenon of the bentonite into fractures. (author)
Natural Fractures Characterization and In Situ Stresses Inference in a Carbonate Reservoir—An Integrated Approach

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Ali Shafiei

2018-02-01

Full Text Available In this paper, we characterized the natural fracture systems and inferred the state of in situ stress field through an integrated study in a very complex and heterogeneous fractured carbonate reservoir. Relative magnitudes and orientations of the in-situ principal stresses in a naturally fractured carbonate heavy oil field were estimated with a combination of available data (World Stress Map, geological and geotectonic evidence, outcrop studies and techniques (core analysis, borehole image logs and Side View Seismic Location. The estimates made here using various tools and data including routine core analysis and image logs are confirmatory to estimates made by the World Stress Map and geotectonic facts. NE-SW and NW-SE found to be the dominant orientations for maximum and minimum horizontal stresses in the study area. In addition, three dominant orientations were identified for vertical and sub-vertical fractures atop the crestal region of the anticlinal structure. Image logs found useful in recognition and delineation of natural fractures. The results implemented in a real field development and proved practical in optimal well placement, drilling and production practices. Such integrated studies can be instrumental in any E&P projects and related projects such as geological CO2 sequestration site characterization.
Geological and geophysical evaluation of the Ajana area’s groundwater potential, southwestern Nigeria

Directory of Open Access Journals (Sweden)

O.M Ajibade

2011-06-01

Full Text Available Acombined geological and geophysical evaluation was madeof the groundwater potential of the Ajana, RemoNorth area in south-western Nigeria; the geology and other structural features of the rocks there strongly influenced and correlated the aquifers' storability and transmissivity. Geological mapping revealed that the area was made up of granite, quartzite and varieties of gneiss, some of which have good secondary porosity and permeability. Ten vertical electric soundings (VES stations were established using a Schlumberger electrode array. Five geoelectric layers consisting of topsoil, sand,
clayey-sandy, fractured / weathered basement and fresh bedrock were delineated. The aquifer layers were the 38.3m thick 283 ?m resistivity sand/sandy clay and 55 - 518 ?m resistivity fractured/weathered basement. Other geoelectric parameters used in evaluating the area's hydrogeological potential included curve type, anisotropy coefficient and reflection coefficient - The QH curve type was predominant in the area. The anisotropy Coefficients suggested VES stations having high groundwater potential ranging from 1.4 - 1.56; while the reflection coefficients for the area ranged from 0.21 - 0.99. The overall results showed that VES stations 8, 9 and 10 could be possible groundwater sources having high expected yield.
Possible origin, nature, extent and tectomic position of joints and fracture in salt formations

International Nuclear Information System (INIS)

Weiss, H.M.

1984-01-01

The evaluation of about 500 bibliographic references for the safe ultimate storage in salt leds to the following results: fractures in rock salt and potash salt are formed in all types of storage, fractures are less numerous in a vertical storage than in a horizontal storage, nevertheless fissures are found in salt fomations containing liquids or gas undergoing rock pressures, fractures can be created during salt formation. Datation of formations by geologic methods and K-Ar method are considered. Deep formations (about 300m) are liquid and gas-tight, if homogenous and non perturbated. In all German permian formations are found indications of brine accumulation along fractures and tectonic zones
Origins and nature of non-Fickian transport through fractures

Science.gov (United States)

Wang, L.; Cardenas, M. B.

2014-12-01

Non-Fickian transport occurs across all scales within fractured and porous geological media. Fundamental understanding and appropriate characterization of non-Fickian transport through fractures is critical for understanding and prediction of the fate of solutes and other scalars. We use both analytical and numerical modeling, including direct numerical simulation and particle tracking random walk, to investigate the origin of non-Fickian transport through both homogeneous and heterogeneous fractures. For the simple homogenous fracture case, i.e., parallel plates, we theoretically derived a formula for dynamic longitudinal dispersion (D) within Poiseuille flow. Using the closed-form expression for the theoretical D, we quantified the time (T) and length (L) scales separating preasymptotic and asymptotic dispersive transport, with T and L proportional to aperture (b) of parallel plates to second and fourth orders, respectively. As for heterogeneous fractures, the fracture roughness and correlation length are closely associated with the T and L, and thus indicate the origin for non-Fickian transport. Modeling solute transport through 2D rough-walled fractures with continuous time random walk with truncated power shows that the degree of deviation from Fickian transport is proportional to fracture roughness. The estimated L for 2D rough-walled fractures is significantly longer than that derived from the formula within Poiseuille flow with equivalent b. Moreover, we artificially generated normally distributed 3D fractures with fixed correlation length but different fracture dimensions. Solute transport through 3D fractures was modeled with a particle tracking random walk algorithm. We found that transport transitions from non-Fickian to Fickian with increasing fracture dimensions, where the estimated L for the studied 3D fractures is related to the correlation length.
Frictional stability-permeability relationships for fractures in shales

Science.gov (United States)

Fang, Yi; Elsworth, Derek; Wang, Chaoyi; Ishibashi, Takuya; Fitts, Jeffrey P.

2017-03-01

There is wide concern that fluid injection in the subsurface, such as for the stimulation of shale reservoirs or for geological CO2 sequestration (GCS), has the potential to induce seismicity that may change reservoir permeability due to fault slip. However, the impact of induced seismicity on fracture permeability evolution remains unclear due to the spectrum of modes of fault reactivation (e.g., stable versus unstable). As seismicity is controlled by the frictional response of fractures, we explore friction-stability-permeability relationships through the concurrent measurement of frictional and hydraulic properties of artificial fractures in Green River shale (GRS) and Opalinus shale (OPS). We observe that carbonate-rich GRS shows higher frictional strength but weak neutral frictional stability. The GRS fracture permeability declines during shearing while an increased sliding velocity reduces the rate of permeability decline. By comparison, the phyllosilicate-rich OPS has lower friction and strong stability while the fracture permeability is reduced due to the swelling behavior that dominates over the shearing induced permeability reduction. Hence, we conclude that the friction-stability-permeability relationship of a fracture is largely controlled by mineral composition and that shale mineral compositions with strong frictional stability may be particularly subject to permanent permeability reduction during fluid infiltration.
Modeling study on geological environment at Horonobe URL site

International Nuclear Information System (INIS)

Shimo, Michito; Yamamoto, Hajime; Kumamoto, Sou; Fujiwara, Yasushi; Ono, Makoto

2005-02-01

The Horonobe underground research project has been operated by Japan Nuclear Cycle Development Institute to study the geological environment of sedimentary rocks in deep underground. The objectives of this study are to develop a geological environment model, which incorporate the current findings and the data obtained through the geological, geophysical, and borehole investigations at Horonobe site, and to predict the hydrological and geochemical impacts caused by the URL shaft excavation to the surrounding area. A three-dimensional geological structure model was constructed, integrating a large-scale model (25km x 15km) and a high-resolution site-scale model (4km x 4km) that have been developed by JNC. The constructed model includes surface topography, geologic formations (such as Yuchi, Koetoi, Wakkanai, and Masuporo Formations), and two major faults (Ohomagari fault and N1 fault). In hydrogeological modeling, water-conductive fractures identified in Wakkanai Formation are modeled stochastically using EHCM (Equivalent Heterogeneous Continuum Model) approach, to represent hydraulic heterogeneity and anisotropy in the fractured rock mass. Numerical code EQUIV FLO (Shimo et al., 1996), which is a 3D unsaturated-saturated groundwater simulator capable of EHCM, was used to simulate the regional groundwater flow. We used the same model and the code to predict the transient hydrological changes caused by the shaft excavations. Geochemical data in the Horonobe site such as water chemistries, mineral compositions of rocks were collected and summarized into digital datasets. M3 (Multivariate, Mixing and Mass-balance) method developed by SKB (Laaksoharju et al., 1999) was used to identify waters of different origins, and to infer the mixing ratio of these end-members to reproduce each sample's chemistry. Thermodynamic code such as RHREEQC, GWB, and EQ3/6 were used to model chemical reactions that explain the present minerals and aqueous concentrations observed in the site
Geologic Mapping Results for Ceres from NASA's Dawn Mission

Science.gov (United States)

Williams, D. A.; Mest, S. C.; Buczkowski, D.; Scully, J. E. C.; Raymond, C. A.; Russell, C. T.

2017-12-01

NASA's Dawn Mission included a geologic mapping campaign during its nominal mission at dwarf planet Ceres, including production of a global geologic map and a series of 15 quadrangle maps to determine the variety of process-related geologic materials and the geologic history of Ceres. Our mapping demonstrates that all major planetary geologic processes (impact cratering, volcanism, tectonism, and gradation (weathering-erosion-deposition)) have occurred on Ceres. Ceres crust, composed of altered and NH3-bearing silicates, carbonates, salts and 30-40% water ice, preserves impact craters and all sizes and degradation states, and may represent the remains of the bottom of an ancient ocean. Volcanism is manifested by cryovolcanic domes, such as Ahuna Mons and Cerealia Facula, and by explosive cryovolcanic plume deposits such as the Vinalia Faculae. Tectonism is represented by several catenae extending from Ceres impact basins Urvara and Yalode, terracing in many larger craters, and many localized fractures around smaller craters. Gradation is manifested in a variety of flow-like features caused by mass wasting (landslides), ground ice flows, as well as impact ejecta lobes and melts. We have constructed a chronostratigraphy and geologic timescale for Ceres that is centered around major impact events. Ceres geologic periods include Pre-Kerwanan, Kerwanan, Yalodean/Urvaran, and Azaccan (the time of rayed craters, similar to the lunar Copernican). The presence of geologically young cryovolcanic deposits on Ceres surface suggests that there could be warm melt pockets within Ceres shallow crust and the dwarf planet remain geologically active.
On the theory of transport of fluids in fractured media for the safety analysis of a nuclear waste repository

International Nuclear Information System (INIS)

Mukhopadhyay, N.C.

1983-01-01

A systematic theory is developed of the role of fractures in the transport of radionuclides by groundwater through fractured rocks from the nuclear waste repository to be built in deep geologic formations to the biosphere. Fractures are grouped into four ''irreducible'' types: joints, nodes, shear zones, and fracture zones, and their geometrical and sorption characteristics, having bearings on radionuclide transport, are expressed in mathematical terms. The question of radioactivity retention in various fracture types is then carefully studied using idealized geometries to mimic natural forms. Fundamental transport equations are derived for the fracture-pore complex, taking into consideration the special physical characteristics of fractures and the effects of sorption therein
Topographic attributes as a guide for automated detection or highlighting of geological features

Science.gov (United States)

Viseur, Sophie; Le Men, Thibaud; Guglielmi, Yves

2015-04-01

Photogrammetry or LIDAR technology combined with photography allow geoscientists to obtain 3D high-resolution numerical representations of outcrops, generally termed as Digital Outcrop Models (DOM). For over a decade, these 3D numerical outcrops serve as support for precise and accurate interpretations of geological features such as fracture traces or plans, strata, facies mapping, etc. These interpretations have the benefit to be directly georeferenced and embedded into the 3D space. They are then easily integrated into GIS or geomodeler softwares for modelling in 3D the subsurface geological structures. However, numerical outcrops generally represent huge data sets that are heavy to manipulate and hence to interpret. This may be particularly tedious as soon as several scales of geological features must be investigated or as geological features are very dense and imbricated. Automated tools for interpreting geological features from DOMs would be then a significant help to process these kinds of data. Such technologies are commonly used for interpreting seismic or medical data. However, it may be noticed that even if many efforts have been devoted to easily and accurately acquire 3D topographic point clouds and photos and to visualize accurate 3D textured DOMs, few attentions have been paid to the development of algorithms for automated detection of the geological structures from DOMs. The automatic detection of objects on numerical data generally assumes that signals or attributes computed from this data allows the recognition of the targeted object boundaries. The first step consists then in defining attributes that highlight the objects or their boundaries. For DOM interpretations, some authors proposed to use differential operators computed on the surface such as normal or curvatures. These methods generally extract polylines corresponding to fracture traces or bed limits. Other approaches rely on the PCA technology to segregate different topographic plans
Summary of discrete fracture network modelling as applied to hydrogeology of the Forsmark and Laxemar sites

International Nuclear Information System (INIS)

Hartley, Lee; Roberts, David

2013-04-01

The Swedish Nuclear Fuel and Waste Management Company (SKB) is responsible for the development of a deep geological repository for spent nuclear fuel. The permitting of such a repository is informed by assessment studies to estimate the risks of the disposal method. One of the potential risks involves the transport of radionuclides in groundwater from defective canisters in the repository to the accessible environment. The Swedish programme for geological disposal of spent nuclear fuel has involved undertaking detailed surface-based site characterisation studies at two different sites, Forsmark and Laxemar-Simpevarp. A key component of the hydrogeological modelling of these two sites has been the development of Discrete Fracture Network (DFN) concepts of groundwater flow through the fractures in the crystalline rocks present. A discrete fracture network model represents some of the characteristics of fractures explicitly, such as their, orientation, intensity, size, spatial distribution, shape and transmissivity. This report summarises how the discrete fracture network methodology has been applied to model groundwater flow and transport at Forsmark and Laxemar. The account has involved summarising reports previously published by SKB between 2001 and 2011. The report describes the conceptual framework and assumptions used in interpreting site data, and in particular how data has been used to calibrate the various parameters that define the discrete fracture network representation of bedrock hydrogeology against borehole geologic and hydraulic data. Steps taken to confirm whether the developed discrete fracture network models provide a description of regional-scale groundwater flow and solute transport consistent with wider hydraulic tests hydrochemical data from Forsmark and Laxemar are discussed. It illustrates the use of derived hydrogeological DFN models in the simulations of the temperate period hydrogeology that provided input to radionuclide transport
Summary of discrete fracture network modelling as applied to hydrogeology of the Forsmark and Laxemar sites

Energy Technology Data Exchange (ETDEWEB)

Hartley, Lee; Roberts, David

2013-04-15

The Swedish Nuclear Fuel and Waste Management Company (SKB) is responsible for the development of a deep geological repository for spent nuclear fuel. The permitting of such a repository is informed by assessment studies to estimate the risks of the disposal method. One of the potential risks involves the transport of radionuclides in groundwater from defective canisters in the repository to the accessible environment. The Swedish programme for geological disposal of spent nuclear fuel has involved undertaking detailed surface-based site characterisation studies at two different sites, Forsmark and Laxemar-Simpevarp. A key component of the hydrogeological modelling of these two sites has been the development of Discrete Fracture Network (DFN) concepts of groundwater flow through the fractures in the crystalline rocks present. A discrete fracture network model represents some of the characteristics of fractures explicitly, such as their, orientation, intensity, size, spatial distribution, shape and transmissivity. This report summarises how the discrete fracture network methodology has been applied to model groundwater flow and transport at Forsmark and Laxemar. The account has involved summarising reports previously published by SKB between 2001 and 2011. The report describes the conceptual framework and assumptions used in interpreting site data, and in particular how data has been used to calibrate the various parameters that define the discrete fracture network representation of bedrock hydrogeology against borehole geologic and hydraulic data. Steps taken to confirm whether the developed discrete fracture network models provide a description of regional-scale groundwater flow and solute transport consistent with wider hydraulic tests hydrochemical data from Forsmark and Laxemar are discussed. It illustrates the use of derived hydrogeological DFN models in the simulations of the temperate period hydrogeology that provided input to radionuclide transport
Fracture mineralogy of the Forsmark site. SDM-Site Forsmark

Energy Technology Data Exchange (ETDEWEB)

Sandstroem, Bjoern (Dept. of Earth Sciences, Univ. of Goeteborg (Sweden)); Tullborg, Eva-Lena (Terralogica AB, Graabo (Sweden)); Smellie, John (Conterra AB, Luleaa (Sweden)); MacKenzie, Angus B. (SUERC, Scottish Enterprise Technology Park, East Kilbride (United Kingdom)); Suksi, Juhani (Dept. of Chemistry, Univ. of Helsinki, Helsinki (Finland))

2008-08-15

Detailed investigations of the fracture mineralogy and altered wall rock have been carried out as part of the site characterisation programme between 2003 and 2007 at Forsmark. The results have been published in a number of P-reports and in contributions to scientific journals. This report summarises and evaluates the data obtained during the detailed fracture mineralogical studies. The report includes descriptions of the identified fracture minerals and their chemical composition. A sequence of fracture mineralisations has been distinguished and provides information of the low to moderate temperature (brittle) geological and hydrogeological evolution at the site. Special focus has been paid to the chemical and stable isotopic composition of calcite to obtain palaeohydrogeological information. Chemical analyses of bulk fracture filling material have been carried out to identify possible sinks for certain elements and also to reveal the presence of minor phases rich in certain elements which have not been possible to detect by X-ray diffraction (XRD). Statistical analysis of the mineralogy in fractures outside deformation zones (i.e. within fracture domains FFM01, FFM02, FFM03 and FFM06) have been carried out concerning variation of fracture mineral distribution at depth and in different fracture domains. Uranium contents and uranium-series isotopes have been analysed on fracture coating material from hydraulically conductive fractures. Such analyses are also available from the groundwaters and the results are combined in order to reveal recent (< 1 Ma) removal/deposition of uranium in the fracture system. The redox conditions in the fracture system have been evaluated based on mineralogical and chemical indicators as well as Moessbauer analyses

Numerical Study of Critical Role of Rock Heterogeneity in Hydraulic Fracture Propagation

Energy Technology Data Exchange (ETDEWEB)

J. Zhou; H. Huang; M. Deo

2016-03-01

Log and seismic data indicate that most shale formations have strong heterogeneity. Conventional analytical and semi-analytical fracture models are not enough to simulate the complex fracture propagation in these highly heterogeneous formation. Without considering the intrinsic heterogeneity, predicted morphology of hydraulic fracture may be biased and misleading in optimizing the completion strategy. In this paper, a fully coupling fluid flow and geomechanics hydraulic fracture simulator based on dual-lattice Discrete Element Method (DEM) is used to predict the hydraulic fracture propagation in heterogeneous reservoir. The heterogeneity of rock is simulated by assigning different material force constant and critical strain to different particles and is adjusted by conditioning to the measured data and observed geological features. Based on proposed model, the effects of heterogeneity at different scale on micromechanical behavior and induced macroscopic fractures are examined. From the numerical results, the microcrack will be more inclined to form at the grain weaker interface. The conventional simulator with homogeneous assumption is not applicable for highly heterogeneous shale formation.
Geostatistical description of geological heterogeneity in clayey till as input for improved characterization of contaminated sites

DEFF Research Database (Denmark)

Kessler, Timo Christian; Klint, K.E.S.; Renard, P.

2010-01-01

In low-permeability clay tills subsurface transport is governed by preferential flow in sand lenses and fractures. A proper geological model requires the integration of these features, i.e. the spatial distribution of the geological heterogeneities. Detailed mapping of sand lenses has been done...... at a clay till outcrop in Denmark to characterise the shapes and the spatial variability. Further, geostatistics were applied to simulate the distribution and to develop a heterogeneity model that can be incorporated into an existing geological model of, for example, a contaminated site....
Simulation of three-dimensional tectonic stress fields and quantitative prediction of tectonic fracture within the Damintun Depression, Liaohe Basin, northeast China

Science.gov (United States)

Guo, Peng; Yao, Leihua; Ren, Desheng

2016-05-01

Tectonic fractures are important factors that influence oil and natural gas migration and accumulation within "buried hill" reservoirs. To obtain a quantitative forecast of the development and distribution of reservoir fractures in the Damintun Depression, we analyzed the characteristics of regional structural evolution and paleotectonic stress field setting. A reasonable geological model of the research area was built based on an interpretation of the geological structure, a test for rock mechanics, and experiment on acoustic emission. Thereafter, a three-dimensional paleotectonic stress field during the Yanshan movement was simulated by the finite element method. Rock failure criterion and comprehensive evaluation coefficient of fractures were used to determine the quantitative development of fractures and predict zones that are prone to fracture development. Under an intense Yanshan movement, high stress strength is distributed in the south and northeast parts of the study area, where stress is extremely high. The fracture development zones are mainly controlled by the tectonic stress field and typically located in the same areas as those of high maximum principal and shear stresses. The predicted areas with developed fractures are consistent with the wells with high fracture linear density and in locations with high-producing oil and gas wells.
Geologic flow characterization using tracer techniques

International Nuclear Information System (INIS)

Klett, R.D.; Tyner, C.E.; Hertel, E.S. Jr.

1981-04-01

A new tracer flow-test system has been developed for in situ characterization of geologic formations. This report describes two sets of test equipment: one portable and one for testing in deep formations. Equations are derived for in situ detector calibration, raw data reduction, and flow logging. Data analysis techniques are presented for computing porosity and permeability in unconfined isotropic media, and porosity, permeability and fracture characteristics in media with confined or unconfined two-dimensional flow. The effects of tracer pulse spreading due to divergence, dispersion, and porous formations are also included
Core fracture analysis applied to ground water flow systems: Chickamauga Group, Oak Ridge, Tennessee

International Nuclear Information System (INIS)

Bittner, E.; Dreier, R.B.

1989-01-01

The objective of this study is to correlate hydrologic properties with detailed geologic fabrics and to investigate the influence of a complex geologic setting on ground water systems. The Chickamauga Group (CH) located in Bethel Valley on the DOE Oak Ridge Reservation is comprised of limestones and interbedded shales. Five core holes (CH 1-5), oriented across strike, provide a cross section of the CH and were mapped for fracture density, orientation and cross-cutting relationships as well as lithologic variations. Correlation of structural and lithologic features with downhole geophysical logs and hydraulic conductivity values shows a relationship between lithology, fracture density and increased permeability in an otherwise low-permeability environment. Structures identified as influential in enhancing hydraulic conductivity include contractional bedding plane and tectonic stylolites and extensional fractures. Three sets of extensional fractures are indicated by cross-cutting relationships and various degrees of veining. Hydraulic conductivity values (K) for the five wells indicate two ground water flow systems in the valley. A shallow system (up to 150 feet deep) shows a range in K from 10E-4 centimeters per second to 10E-6 centimeters per second. Shallow horizons show more open fractures than are observed at depth, and these fractures appear to control the enhanced K in the shallow system. A subhorizontal interface that is not defined by pre-existing structures or a stratigraphic horizon separates the two flow systems. The deeper system ranges in K values from 10E-9 centimeters per second to 10E-5 centimeters per second. The higher K values at depth correspond to increased fracture density at lithologic contacts, zones of tectonic stylolitization and partially veined extension fractures. 11 refs., 11 figs., 2 tabs
Dissolution along faults-fractures and hypogenic karst in carbonates: examples from Brazil

Science.gov (United States)

Ennes-Silva, Renata; Cazarin, Caroline; Bezerra, Francisco; Auler, Augusto; Klimchouk, Alexander

2015-04-01

Dissolution along faults-fractures and hypogenic karst in carbonates: examples from Brazil Ennes-Silva, R.A; Cazarin, C.L.; Bezerra, F.H.; Auler, A.S.; Klimchouk, A.B. Dissolution along zones of preferential flow enhances anisotropy in geological media and increases its complexity. Changes in parameters such as porosity and permeability due to diagenesis and presence of ascendant fluids along fractures and faults can be responsible for hypogenic karstic system. The present study investigates the relationship between lithofacies, tectonics and karstification in the Neoproterozoic Salitre Formation, located in the central-eastern Brazil. This unit comprises several systems of caves including the Toca da Boa Vista and da Barriguda hypogenic caves, the largests in South America, and focus of this study. We focused on cave mapping and morphogenetic analysis, determination of petrophysical properties, thin-section description, micro-tomography, and isotopic analysis. The Salitre Formation, deposited in an epicontinental sea, comprises mud/wakestones, grainstones, microbial facies, and fine siliciclastic rocks. Passages occur in several levels within ca. 60 m thick cave-forming section, limited at the top by lithofacies with low permeability and fractures. Cave development occurred in phreatic sluggish-flow environment with overall upwelling flow. Fluids rise via cross-formational fractures and were distributed laterally within the cave-forming section using geological heterogeneities to eventually discharge up through outlets breaching across the upper confining beds. Maps of conduits show preferred directions for development of conduits: NNE-SSW and E-W. These two directions represents a relation between structures and hypogenic morphology. Joints, axis fold and fractures allowed pathways to the fluid rises, and then development of channels of entrance (feeders), outputs (outlets) and some cupolas, which are clearly aligned to fractures. Our data indicate several events
Seismic fracture detection of shale gas reservoir in Longmaxi formation, Sichuan Basin, China

Science.gov (United States)

Lu, Yujia; Cao, Junxing; Jiang, Xudong

2017-11-01

In the shale reservoirs, fractures play an important role, which not only provide space for the oil and gas, but also offer favorable petroleum migration channel. Therefore, it is of great significance to study the fractures characteristics in shale reservoirs for the exploration and development of shale gas. In this paper, four analysis technologies involving coherence, curvature attribute, structural stress field simulation and pre-stack P-wave azimuthal anisotropy have been applied to predict the fractures distribution in the Longmaxi formation, Silurian, southeast of Sichuan Basin, China. By using the coherence and curvature attribute, we got the spatial distribution characteristics of fractures in the study area. Structural stress field simulation can help us obtain distribution characteristics of structural fractures. And using the azimuth P-wave fracture detection technology, we got the characteristics about the fracture orientation and density of this region. Application results show that there are NW and NE fractures in the study block, which is basically consistent with the result of log interpretation. The results also provide reliable geological basis for shale gas sweet spots prediction.
Underground disposal for radioactive wastes: study of the thermal impact in a fractured medium

International Nuclear Information System (INIS)

Coudrain, A.; Hosanski, J.M.; Ledoux, E.; Vouille, G.

1982-01-01

Radioactive waste storage in deep geologic formations, like granitic rocks, is one of the solutions studied for long-life radioactive wastes disposal. The study, presented in this document, has been developed in five stages: (1) theorical analysis of heat transfer in a fractured medium; bench-scale experiments (2) to study the convection in an artificial fracture with a punctual heat source, and, (3) in a real fracture with a spread heat source; (4) influence of the thermal stresses on the permeability of a fracture; (5) and finally, the mathematical model, validated in laboratory, used to simulate water and heat transfer, allows to discuss the radionuclides migration from an hydrodynamical point of view
Determining the REV for Fracture Rock Mass Based on Seepage Theory

Directory of Open Access Journals (Sweden)

Lili Zhang

2017-01-01

Full Text Available Seepage problems of the fractured rock mass have always been a heated topic within hydrogeology and engineering geology. The equivalent porous medium model method is the main method in the study of the seepage of the fractured rock mass and its engineering application. The key to the method is to determine a representative elementary volume (REV. The FractureToKarst software, that is, discrete element software, is a main analysis tool in this paper and developed by a number of authors. According to the standard of rock classification established by ISRM, this paper aims to discuss the existence and the size of REV of fractured rock masses with medium tractility and provide a general method to determine the existence of REV. It can be gleaned from the study that the existence condition of fractured rock mass with medium tractility features average fracture spacing smaller than 0.6 m. If average fracture spacing is larger than 0.6 m, there is no existence of REV. The rationality of the model is verified by a case study. The present research provides a method for the simulation of seepage field in fissured rocks.
Fracture mapping for radionuclide migration studies in the Climax granite

International Nuclear Information System (INIS)

Thorpe, R.; Springer, J.

1981-05-01

As part of LLNL's program on radionuclide migration through fractured rock, major geologic discontinuities have been mapped and characterized at the 420 m level in the Climax Stock, adjacent to LLNL's Spent Fuel Test. Persistence or continuity of features was the principal sampling criterion, and ninety major fractures and faults were mapped in the main access and tail drifts. Although the purpose and nature of this study was different from previous fracture surveys in the Climax Stock, the results are generally consistent in that three predominant fracture sets are identified: NW strike/vertical, NE strike/vertical, NW strike/subhorizontal. The frequency of major features in the main access drift is somewhat higher than in the tail drift. Those mapped in the main access drift are generally braided, stepped, or en echelon, while those in the tail drift appear to be more distinct and planar. Several of the fractures in the tail drift lie in the NE/vertical set, while most form an entirely different set oriented N5E/55NW. Subhorizontal fractures were common to both drifts. An area of seepage associated with some of these low-angle features was mapped in the main access drift
Permeability of Granite Including Macro-Fracture Naturally Filled with Fine-Grained Minerals

Science.gov (United States)

Nara, Yoshitaka; Kato, Masaji; Niri, Ryuhei; Kohno, Masanori; Sato, Toshinori; Fukuda, Daisuke; Sato, Tsutomu; Takahashi, Manabu

2018-03-01

Information on the permeability of rock is essential for various geoengineering projects, such as geological disposal of radioactive wastes, hydrocarbon extraction, and natural hazard risk mitigation. It is especially important to investigate how fractures and pores influence the physical and transport properties of rock. Infiltration of groundwater through the damage zone fills fractures in granite with fine-grained minerals. However, the permeability of rock possessing a fracture naturally filled with fine-grained mineral grains has yet to be investigated. In this study, the permeabilities of granite samples, including a macro-fracture filled with clay and a mineral vein, are investigated. The permeability of granite with a fine-grained mineral vein agrees well with that of the intact sample, whereas the permeability of granite possessing a macro-fracture filled with clay is lower than that of the macro-fractured sample. The decrease in the permeability is due to the filling of fine-grained minerals and clay in the macro-fracture. It is concluded that the permeability of granite increases due to the existence of the fractures, but decreases upon filling them with fine-grained minerals.
Recent Developments in Multiscale and Multiphase Modelling of the Hydraulic Fracturing Process

Directory of Open Access Journals (Sweden)

Yong Sheng

2015-01-01

Full Text Available Recently hydraulic fracturing of rocks has received much attention not only for its economic importance but also for its potential environmental impact. The hydraulically fracturing technique has been widely used in the oil (EOR and gas (EGR industries, especially in the USA, to extract more oil/gas through the deep rock formations. Also there have been increasing interests in utilising the hydraulic fracturing technique in geological storage of CO2 in recent years. In all cases, the design and implementation of the hydraulic fracturing process play a central role, highlighting the significance of research and development of this technique. However, the uncertainty behind the fracking mechanism has triggered public debates regarding the possible effect of this technique on human health and the environment. This has presented new challenges in the study of the hydraulic fracturing process. This paper describes the hydraulic fracturing mechanism and provides an overview of past and recent developments of the research performed towards better understandings of the hydraulic fracturing and its potential impacts, with particular emphasis on the development of modelling techniques and their implementation on the hydraulic fracturing.
Comparative study of geological, hydrological, and geophysical borehole investigations

International Nuclear Information System (INIS)

Magnusson, K.A.; Duran, O.

1984-09-01

The understanding of the permeability of the bedrock can be improved by supplementing the results of the water injection tests with information from core mapping, TB-inspection and borehole geophysics. The comparison between different borehole investigations encompasses core mapping, TV-inspection and various geophysical bore hole measurements. The study includes data from two different study areas, namely Kraakemaala and Finnsjoen. In these two areas, extensive geological, hydrological and geophysical investigation have been carried out. The fractures and microfractures in crystalline rock constitute the main transport paths for both groundwater and electric currents. They will therefore govern both the permeability and the resistivity of the rock. In order to get a better understanding of the influence of fractures on permeability and resistivity, a detailed comparison has been made between the hydraulic conductivity, respectively, and the character of fractures in the core and the borehole wall. The fractures show very large variations in hydraulic conductivity. Microfractures and most of the thin fractures have no measurable hydraulic conductivity (in this case -9 m s -1 ), while test sections which contain a single isloated fracture can have no measurable, to rather high hydraulic conductivities (> 10 -7 m s -1 ). Wide fracture zones often have hydraulic conductivities which vary from very low (less than 2 x 10 -9 m s -1 ) to high values (10 -5 m s -1 ). This indicates that the hydraulic conductivity is governed by a few discrete fractures. The resistivity shows a continous variation in the range 1,000- 100,000 ohm-m and a relatively poor correlation with hydraulic conductivities. The observed difference is considered to the effect of restriction of water flow on a few channels, while electric surface condition, i.e. current transport through thin water films, makes current transport possible through fractures with very small aperatures. (Author)
Exploration methods for granitic natural stones – geological and topographical aspects from case studies in Finland

Directory of Open Access Journals (Sweden)

Olavi Selonen

2014-06-01

Full Text Available Regional and local geological constraints for location of natural stone deposits in glaciated terrains of southern and central Finland have been studied and applied to practical exploration for natural stone. A list of geological and topographical aspects to be considered in exploration, is presented. Important aspects refer to: 1. Regional geology of the target area. 2. Magmatism (type and structure of intrusion, relative time of pluton emplacement. 3. Metamorphism (grade, mineral composition, parent material. 4. Deformation (lineaments, shear zones, folding, fault zones, fracture zones, shape preferred mineral orientations, and 5. Topography (relative elevation, micro topography. The proposed aspects can be used as geological guidelines in exploration for granitic natural stones.
Hydraulic Parameter Generation Technique Using a Discrete Fracture Network with Bedrock Heterogeneity in Korea

Directory of Open Access Journals (Sweden)

Jae-Yeol Cheong

2017-12-01

Full Text Available In instances of damage to engineered barriers containing nuclear waste material, surrounding bedrock is a natural barrier that retards radionuclide movement by way of adsorption and delay due to groundwater flow through highly tortuous fractured rock pathways. At the Gyeongju nuclear waste disposal site, groundwater mainly flows through granitic and sedimentary rock fractures. Therefore, to understand the nuclide migration path, it is necessary to understand discrete fracture networks based on heterogeneous fracture orientations, densities, and size characteristics. In this study, detailed heterogeneous fracture distribution, including the density and orientation of the fractures, was considered for a region that has undergone long periods of change from various geological activities at and around the Gyeongju site. A site-scale discrete fracture network (DFN model was constructed taking into account: (i regional fracture heterogeneity constrained by a multiple linear regression analysis of fracture intensity on faults and electrical resistivity; and (ii the connectivity of conductive fractures having fracture hydraulic parameters, using transient flow simulation. Geometric and hydraulic heterogeneity of the DFN was upscaled into equivalent porous media for flow and transport simulation for a large-scale model.
Geology of Reskajeage Farm Quarry (Nirex research site on Cornish slate)

International Nuclear Information System (INIS)

Hancock, P.L.; North, C.P.

1989-08-01

Convection with any water flow is the most likely way in which any radionuclides escaping from deep disposal of radioactive waste in hard fractured rock could return to the surface. Hence the interest in water flow and mass transport through fractures for establishing the safety of such disposal. Earlier work on this subject was carried out in granite at Troon in Cornwall. This work provided statistical data about individual fractures and helped with the development of realistic modelling of flow and transport (Bourke 1985 and 1988). Validation of this modelling was however impractical. Access was obtained to another site with a much smaller separation between fractures in slate to allow measurement of flow and transport through representative volumes of 10m dimensions. Individual fracture statistics are being determined so that modelling predictions can be theoretically made for experimental proving. The programme at the site was begun with a geological investigation. The main findings are that the somewhat heterogeneous hard rock consists mostly of siltstone with some sandstone layers, that it is not untypically broken by many fractures and that a comparatively major (3m wide) fault with slip of about a metre between its faces crossing part of the site. These findings are described in detail in the report. (author)
Chemical Signatures of and Precursors to Fractures Using Fluid Inclusion Stratigraphy

Energy Technology Data Exchange (ETDEWEB)

Lorie M. Dilley

2011-03-30

chemical signature of fluid inclusions between open and closed fractures as well as differences in the chemical signature of open fractures between geothermal systems. Our hypothesis is that open fracture systems can be identified by their FIS chemical signature; that there are differences based on the mineral assemblages and geology of the system; and that there are chemical precursors in the wall rock above open, large fractures. Specific goals for this project are: (1) To build on the preliminary results which indicate that there are differences in the FIS signatures between open and closed fractures by identifying which chemical species indicate open fractures in both active geothermal systems and in hot, dry rock; (2) To evaluate the FIS signatures based on the geology of the fields; (3) To evaluate the FIS signatures based on the mineral assemblages in the fracture; and (4) To determine if there are specific chemical signatures in the wall rock above open, large fractures. This method promises to lower the cost of geothermal energy production in several ways. Knowledge of productive fractures in the boreholes will allow engineers to optimize well production. This information can aid in well testing decisions, well completion strategies, and in resource calculations. It will assist in determining the areas for future fracture enhancement. This will develop into one of the techniques in the 'tool bag' for creating and managing Enhanced Geothermal Systems.
Predictive geology in nuclear-waste management

International Nuclear Information System (INIS)

Brotzen, O.

1982-01-01

The present situation at a specific site on the Baltic Shield is viewed in the light of its geologic history. Prediction, at a given level of confidence and from a limited number of drillholes of the minimum average spacing of conductive zones in subsurface rocks of low-hydraulic conductivity, is based on a combination of the binomial and Poisson distributions, regarding the holes as a profile sampling and assuming a cubic pattern of fractures. The data provide an empirical basis for linking the nature and frequency of past geologic events to their local effects. Special attention is given to the preservation of tectonic blocks of large rock volumes with low-hydraulic conductivity throughout the present cratonic stage, whereas intermittent movement can be traced in marked fault zones bordering the Shield and three different orogenies affected the surrounding regions. Rock mechanical, stochastic, and deterministic approaches are utilized to predict future effects from this basis. (author)
Predictive geology in nuclear waste management

International Nuclear Information System (INIS)

Brotzen, O.

1980-07-01

The present situation at a specific site in the Baltic Shield is viewed in the light of its geologic history. Prediction, at a given level of confidence and from a limited number of drillholes, of the minimum average spacing of conductive zones in subsurface rocks of low hydraulic conductivity is based on a combination of the binomial and Poisson distribution, regarding the holes as a profile sampling and assuming a cubic pattern of fractures. The data provide an empirical basis for linking the nature and frequency of past geologic events to their local effects. Special attenetion is given to the preservation of tectonic blocks of large rock-volumes with very low hydraulic conductivity throughout the present cratonic stage, during which intermittent movement took place in marked fault-zones bordering the Shield, and three different orogenies affected the surrounding regions. Rock-mechanical, stochastic and deterministic approaches are utilized to predict future effects from this basis. (Author)
Characterization on the Fracture system in jurassic granitic rocks: Kosung and Yusung areas

Energy Technology Data Exchange (ETDEWEB)

Kim, Kyung Su; Bae, Dae Seok; Kim, Chun Soo; Park, Byung Yoon; Koh, Yong Kweon

2001-03-01

The safety of waste disposal can be achieved by a complete isolation of radioactive wastes from biosphere or by a retardation of nuclide migration to reach an acceptable dose level. For the deep geological disposal of high-level radioactive waste, the potential pathways of nuclide primarily depend on the spatial distribution characteristics of conductive fractures in rock mass. Major key issues in the quantification of fracture system for a disposal site are involved in classification criteria, hydraulic parameters, geometry, field investigation methods etc. This research aims to characterize the spatial distribution characteristics of regional lineaments and background fractures in eastern and western-type granite rock mass.

Characterization on the Fracture system in jurassic granitic rocks: Kosung and Yusung areas

International Nuclear Information System (INIS)

Kim, Kyung Su; Bae, Dae Seok; Kim, Chun Soo; Park, Byung Yoon; Koh, Yong Kweon

2001-03-01

The safety of waste disposal can be achieved by a complete isolation of radioactive wastes from biosphere or by a retardation of nuclide migration to reach an acceptable dose level. For the deep geological disposal of high-level radioactive waste, the potential pathways of nuclide primarily depend on the spatial distribution characteristics of conductive fractures in rock mass. Major key issues in the quantification of fracture system for a disposal site are involved in classification criteria, hydraulic parameters, geometry, field investigation methods etc. This research aims to characterize the spatial distribution characteristics of regional lineaments and background fractures in eastern and western-type granite rock mass
Mineral resources, geologic structure, and landform surveys

Science.gov (United States)

Lattman, L. H.

1973-01-01

The use of ERTS-1 imagery for mineral resources, geologic structure, and landform surveys is discussed. Four categories of ERTS imagery application are defined and explained. The types of information obtained by the various multispectral band scanners are analyzed. Samples of land use maps and tectoning and metallogenic models are developed. It is stated that the most striking features visible on ERTS imagery are regional lineaments, or linear patterns in the topography, which reflect major fracture zones extending upward from the basement of the earth.
Site characterization and validation - validation drift fracture data, stage 4

International Nuclear Information System (INIS)

Bursey, G.; Gale, J.; MacLeod, R.; Straahle, A.; Tiren, S.

1991-08-01

This report describes the mapping procedures and the data collected during fracture mapping in the validation drift. Fracture characteristics examined include orientation, trace length, termination mode, and fracture minerals. These data have been compared and analysed together with fracture data from the D-boreholes to determine the adequacy of the borehole mapping procedures and to assess the nature and degree of orientation bias in the borehole data. The analysis of the validation drift data also includes a series of corrections to account for orientation, truncation, and censoring biases. This analysis has identified at least 4 geologically significant fracture sets in the rock mass defined by the validation drift. An analysis of the fracture orientations in both the good rock and the H-zone has defined groups of 7 clusters and 4 clusters, respectively. Subsequent analysis of the fracture patterns in five consecutive sections along the validation drift further identified heterogeneity through the rock mass, with respect to fracture orientations. These results are in stark contrast to the results form the D-borehole analysis, where a strong orientation bias resulted in a consistent pattern of measured fracture orientations through the rock. In the validation drift, fractures in the good rock also display a greater mean variance in length than those in the H-zone. These results provide strong support for a distinction being made between fractures in the good rock and the H-zone, and possibly between different areas of the good rock itself, for discrete modelling purposes. (au) (20 refs.)
Electrical Conductivity Distributions in Discrete Fluid-Filled Fractures

Science.gov (United States)

James, S. C.; Ahmmed, B.; Knox, H. A.; Johnson, T.; Dunbar, J. A.

2017-12-01

It is commonly asserted that hydraulic fracturing enhances permeability by generating new fractures in the reservoir. Furthermore, it is assumed that in the fractured system predominant flow occurs in these newly formed and pre-existing fractures. Among the phenomenology that remains enigmatic are fluid distributions inside fractures. Therefore, determining fluid distribution and their associated temporal and spatial evolution in fractures is critical for safe and efficient hydraulic fracturing. Previous studies have used both forward modeling and inversion of electrical data to show that a geologic system consisting of fluid filled fractures has a conductivity distribution, where fractures act as electrically conductive bodies when the fluids are more conductive than the host material. We will use electrical inversion for estimating electrical conductivity distribution within multiple fractures from synthetic and measured data. Specifically, we will use data and well geometries from an experiment performed at Blue Canyon Dome in Socorro, NM, which was used as a study site for subsurface technology, engineering, and research (SubTER) funded by DOE. This project used a central borehole for energetically stimulating the system and four monitoring boreholes, emplaced in the cardinal directions. The electrical data taken during this project used 16 temporary electrodes deployed in the stimulation borehole and 64 permanent electrodes in the monitoring wells (16 each). We present results derived using E4D from scenarios with two discrete fractures, thereby discovering the electric potential response of both spatially and temporarily variant fluid distribution and the resolution of fluid and fracture boundaries. These two fractures have dimensions of 3m × 0.01m × 7m and are separated by 1m. These results can be used to develop stimulation and flow tests at the meso-scale that will be important for model validation. Sandia National Laboratories is a multi
A comparison of fracture styles in two granite bodies of the Superior Province

International Nuclear Information System (INIS)

Stone, D.; Kamineni, D.C.; Brown, A.; Everitt, R.

1989-01-01

A quantitative comparison is made between fracture styles in two late Archean instrusions of the Superior Province - the Lac du Bonnet Batholith (LDBB) and Eye-Dashwa Pluton (EDP). These instrusions have a similar geological setting, similar mineral and chemical composition, and similar physical properties but vary markedly in volume (LDBB = 9060 km 3 ; EDP = 122 km 3 ). The fracture style of the LDBB consists of mainly low-angle thrust faults within otherwise poorly fractured granite. Subvertical fractures are restricted to within 200 m of surface or zones encompassing the thrust faults. The mineral assemblage chlorite - iron oxide - carbonate is widespread in fractures. In contrast, fractures of the EDP are closely spaced, variably oriented, pervasive to depth, and dominated by subvertical transcurrent faults. Epidote is an abundant fracture-filling material. Most fractures formed in response to Early Proterozoic compression under low-greenschist conditions in the LDBB and upper-greenschist conditions in the EDP. Fractures in both intrusions were subsequently rejuvenated (clay - iron oxide filling materials) without appreciable modification to fracture styles. The presence of a strong planar fabric at one site, variation in the intensity of Early Proterozoic tectonism, and prolonged plastic deformation in the large LDBB are cited as possible causes for the observed variation in fracture styles
A comparison of fracture styles in two granite bodies of the Superior Province

Energy Technology Data Exchange (ETDEWEB)

Stone, D; Kamineni, D C; Brown, A; Everitt, R [Atomic Energy of Canada Ltd., Pinawa, MB (Canada). Whiteshell Nuclear Research Establishment

1989-02-01

A quantitative comparison is made between fracture styles in two late Archean instrusions of the Superior Province - the Lac du Bonnet Batholith (LDBB) and Eye-Dashwa Pluton (EDP). These instrusions have a similar geological setting, similar mineral and chemical composition, and similar physical properties but vary markedly in volume (LDBB = 9060 km{sup 3}; EDP = 122 km{sup 3}). The fracture style of the LDBB consists of mainly low-angle thrust faults within otherwise poorly fractured granite. Subvertical fractures are restricted to within 200 m of surface or zones encompassing the thrust faults. The mineral assemblage chlorite - iron oxide - carbonate is widespread in fractures. In contrast, fractures of the EDP are closely spaced, variably oriented, pervasive to depth, and dominated by subvertical transcurrent faults. Epidote is an abundant fracture-filling material. Most fractures formed in response to Early Proterozoic compression under low-greenschist conditions in the LDBB and upper-greenschist conditions in the EDP. Fractures in both intrusions were subsequently rejuvenated (clay - iron oxide filling materials) without appreciable modification to fracture styles. The presence of a strong planar fabric at one site, variation in the intensity of Early Proterozoic tectonism, and prolonged plastic deformation in the large LDBB are cited as possible causes for the observed variation in fracture styles.
Evidence for the interior evolution of Ceres from geologic analysis of fractures

Science.gov (United States)

Scully, Jennifer E. C.; Buczkowski, Debra; Schmedemann, Nico; Raymond, Carol A.; Castillo-Rogez, Julie C.; Scott King,; Bland, Michael T.; Ermakov, Anton; O'Brien, D.P.; Marchi, S.; Longobardo, A.; Russell, C.T.; Fu, R.R.; Neveu, M.

2017-01-01

Ceres is the largest asteroid belt object, and the Dawn spacecraft observed Ceres since 2015. Dawn observed two morphologically distinct linear features on Ceres's surface: secondary crater chains and pit chains. Pit chains provide unique insights into Ceres's interior evolution. We interpret pit chains called the Samhain Catenae as the surface expression of subsurface fractures. Using the pit chains' spacings, we estimate that the localized thickness of Ceres's fractured, outer layer is approximately ≥58 km, at least ~14 km greater than the global average. We hypothesize that extensional stresses, induced by a region of upwelling material arising from convection/diapirism, formed the Samhain Catenae. We derive characteristics for this upwelling material, which can be used as constraints in future interior modeling studies. For example, its predicted location coincides with Hanami Planum, a high-elevation region with a negative residual gravity anomaly, which may be surficial evidence for this proposed region of upwelling material.
Defining the natural fracture network in a shale gas play and its cover succession: The case of the Utica Shale in eastern Canada

Science.gov (United States)

Ladevèze, P.; Séjourné, S.; Rivard, C.; Lavoie, D.; Lefebvre, R.; Rouleau, A.

2018-03-01

In the St. Lawrence sedimentary platform (eastern Canada), very little data are available between shallow fresh water aquifers and deep geological hydrocarbon reservoir units (here referred to as the intermediate zone). Characterization of this intermediate zone is crucial, as the latter controls aquifer vulnerability to operations carried out at depth. In this paper, the natural fracture networks in shallow aquifers and in the Utica shale gas reservoir are documented in an attempt to indirectly characterize the intermediate zone. This study used structural data from outcrops, shallow observation well logs and deep shale gas well logs to propose a conceptual model of the natural fracture network. Shallow and deep fractures were categorized into three sets of steeply-dipping fractures and into a set of bedding-parallel fractures. Some lithological and structural controls on fracture distribution were identified. The regional geologic history and similarities between the shallow and deep fracture datasets allowed the extrapolation of the fracture network characterization to the intermediate zone. This study thus highlights the benefits of using both datasets simultaneously, while they are generally interpreted separately. Recommendations are also proposed for future environmental assessment studies in which the existence of preferential flow pathways and potential upward fluid migration toward shallow aquifers need to be identified.
Characterization of subsurface geologic structure for potential water resources near the Villages of Moenkopi, Arizona, 2009--2010

Science.gov (United States)

Macy, Jamie P.

2012-01-01

The Hopi Tribe depends on groundwater as their primary drinking-water source in the area of the Villages of Moenkopi, in northeastern Arizona. Growing concerns of the potential for uranium contamination at the Moenkopi water supply wells from the Tuba City Landfill prompted the need for an improved understanding of subsurface geology and groundwater near Moenkopi. Information in this report provides the Hopi Tribe with new hydrogeologic information that provides a better understanding of groundwater resources near the Villages of Moenkopi. The U.S. Geological Survey in cooperation with the U.S. Bureau of Reclamation and the Hopi Tribe used the controlled source audio-frequency magnetotelluric (CSAMT) geophysical technique to characterize the subsurface near Moenkopi from December 2009 to September 2010. A total of six CSAMT profiles were surveyed to identify possible fracturing and faulting in the subsurface that provides information about the occurrence and movement of groundwater. Inversion results from the six CSAMT lines indicated that north to south trending fractures are more prevalent than east to west. CSAMT Lines A and C showed multiple areas in the Navajo Sandstone where fractures are present. Lines B, D, E, and F did not show the same fracturing as Lines A and C.
Extending Topological Approaches to Microseismic-Derived 3D Fracture Networks

Science.gov (United States)

Urbancic, T.; Bosman, K.; Baig, A.; Ardakani, E. P.

2017-12-01

Fracture topology is important for determining the fluid-flow characteristics of a fracture network. In most unconventional petroleum applications, flow through subsurface fracture networks is the primary source of production, as matrix permeability is often in the nanodarcy range. Typical models of reservoir discrete fracture networks (DFNs) are constructed using fracture orientation and average spacing, without consideration of how the connectivity of the fracture network aids the percolation of hydrocarbons back to the wellbore. Topological approaches to DFN characterization have been developed and extensively used in analysis of outcrop data and aerial photography. Such study of the surface expression of fracture networks is straight-forward, and the physical form of the observed fractures is directly reflected in the parameters used to describe the topology. However, this analysis largely ignores the three-dimensional nature of natural fracture networks, which is difficult to define accurately in geological studies. SMTI analysis of microseismic event distributions can produce DFNs, where each event is represented by a penny-shaped crack with radius and orientation determined from the frequency content of the waveforms and assessment of the slip instability of the potential fracture planes, respectively. Analysis of the geometric relationships between a set of fractures can provide details of intersections between fractures, and thus the topological characteristics of the fracture network. Extension of existing 2D topology approaches to 3D fracture networks is non-trivial. In the 2D case, a fracture intersection is a single point (node), and branches connect adjacent nodes along fractures. For the 3D case, intersection "nodes" become lines, and connecting nodes to find branches becomes more complicated. There are several parameters defined in 2D topology to quantify the connectivity of the fracture network. Equivalent quantities must be defined and calibrated
Statistical methodology for discrete fracture model - including fracture size, orientation uncertainty together with intensity uncertainty and variability

Energy Technology Data Exchange (ETDEWEB)

Darcel, C. (Itasca Consultants SAS (France)); Davy, P.; Le Goc, R.; Dreuzy, J.R. de; Bour, O. (Geosciences Rennes, UMR 6118 CNRS, Univ. def Rennes, Rennes (France))

2009-11-15

Investigations led for several years at Laxemar and Forsmark reveal the large heterogeneity of geological formations and associated fracturing. This project aims at reinforcing the statistical DFN modeling framework adapted to a site scale. This leads therefore to develop quantitative methods of characterization adapted to the nature of fracturing and data availability. We start with the hypothesis that the maximum likelihood DFN model is a power-law model with a density term depending on orientations. This is supported both by literature and specifically here by former analyses of the SKB data. This assumption is nevertheless thoroughly tested by analyzing the fracture trace and lineament maps. Fracture traces range roughly between 0.5 m and 10 m - i e the usual extension of the sample outcrops. Between the raw data and final data used to compute the fracture size distribution from which the size distribution model will arise, several steps are necessary, in order to correct data from finite-size, topographical and sampling effects. More precisely, a particular attention is paid to fracture segmentation status and fracture linkage consistent with the DFN model expected. The fracture scaling trend observed over both sites displays finally a shape parameter k{sub t} close to 1.2 with a density term (alpha{sub 2d}) between 1.4 and 1.8. Only two outcrops clearly display a different trend with k{sub t} close to 3 and a density term (alpha{sub 2d}) between 2 and 3.5. The fracture lineaments spread over the range between 100 meters and a few kilometers. When compared with fracture trace maps, these datasets are already interpreted and the linkage process developed previously has not to be done. Except for the subregional lineament map from Forsmark, lineaments display a clear power-law trend with a shape parameter k{sub t} equal to 3 and a density term between 2 and 4.5. The apparent variation in scaling exponent, from the outcrop scale (k{sub t} = 1.2) on one side, to
Block scale interpretation on the spatial distribution of the fracture system in the study sites

Energy Technology Data Exchange (ETDEWEB)

Kim, Kyung Su; Bae, Dae Seok; Kim, Chun Soo; Koh, Yong Kweon; Kim, Geon Young [Korea Atomic Energy Research Institute, Taejeon (Korea)

2002-05-01

The safety of waste disposal can be achieved by a complete isolation of radioactive wastes from biosphere or by a retardation of nuclide migration to reach an acceptable dose level. For the deep geological disposal of high-level radioactive waste, the potential pathways of nuclide primarily depend on the spatial distribution characteristics of conductive fractures in rock mass. This study aims to characterize the spatial distribution characteristics of regional lineaments and background fracture system in eastern and western-type granite rock mass. The spatial distribution characteristics of the fracture system around 500m depth has been estimated based on the homogeneous discontinuity domain except for the highly fractured upper zone. 6 refs., 16 figs., 7 tabs. (Author)
A geologic scenario for catastrophic failure of the Yucca Mountain Nuclear Waste Repository, Nevada

International Nuclear Information System (INIS)

McMackin, M.R.

1993-01-01

A plausible combination of geologic factors leading to failure can be hypothesized for the Yucca Mountain Nuclear Waste Repository. The scenarios is constructed using elementary fault mechanics combined with geologic observations of exhumed faults and published information describing the repository site. The proposed repository site is located in the Basin and Range Province, a region of active crustal deformation demonstrated by widespread seismicity. The Yucca Mountain area has been characterized as tectonically quiet, which in the context of active crustal deformation may indicate the accumulation of the stresses approaching the levels required for fault slip, essentially stick-slip faulting. Simultaneously, dissolution of carbonate rocks in underlying karst aquifers is lowering the bulk strength of the rock that supports the repository site. Rising levels of hydrostatic stress concurrent with a climatically-driven rise in the water table could trigger faulting by decreasing the effective normal stress that currently retards fault slip. Water expelled from collapsing caverns in the underlying carbonate aquifer could migrate upward with sufficient pressure to open existing fractures or create new fractures by hydrofracturing. Water migrating through fractures could reach the repository in sufficient volume to react with heated rock and waste perhaps creating steam explosions that would further enhance fracture permeability. Closure of conduits in the underlying carbonate aquifer could lead to the elevation of the saturated zone above the level of the repository resulting in sustained saturation of radioactive waste in the repository and contamination of through-flowing groundwater
Description of geological data in SKBs database GEOTAB

International Nuclear Information System (INIS)

Sehlstedt, S.; Stark, T.

1991-01-01

Since 1977 the Swedish Nuclear Fuel and Waste Management Co, SKB, has been performing a research and development programme for final disposal of spent nuclear fuel. The purpose of the programme is to acquire knowledge and data of radioactive waste. Measurement for the characterisation of geological, geophysical, hydrogeological and hydrochemical conditions are performed in specific site investigations as well as for geoscientific projects. Large data volumes have been produced since the start of the programme, both raw data and results. During the years these data were stored in various formats by the different institutions and companies that performed the investigations. It was therefore decided that all data from the research and development programme should be gathered in a database. The database, called GEOTAB, is a relational database. The database comprises six main groups of data volumes. These are: Background information, geological data, geophysical data, hydrological and meteorological data, hydrochemical data, and tracer tests. This report deals with geological data and described the dataflow from the measurements at the sites to the result tables in the database. The geological investigations have been divided into three categories, and each category is stored separately in the database. They are: Surface fractures, core mapping, and chemical analyses. (authors)
Polymer-cement interactions towards improved wellbore cement fracture sealants

Science.gov (United States)

Beckingham, B. S.; Iloejesi, C.; Minkler, M. J.; Schindler, A. K.; Beckingham, L. E.

2017-12-01

Carbon capture, utilization, and storage (CCUS) in deep geologic formations is a promising means of reducing point source emissions of CO2. In these systems, CO2 is captured at the source and then injected to be utilized (eg. in enhanced oil recovery or as a working fluid in enhanced geothermal energy plants) or stored in geologic formations such as depleted oil and gas reservoirs or saline aquifers. While CCUS in subsurface systems could aid in reducing atmospheric CO2 emissions, the potential for CO2 leakage from these systems to overlying formations remains a major limitation and poses a significant risk to the security of injected CO2. Thus, improved materials for both initial wellbore isolation and repairing leakage pathways that develop over time are sought. One approach for the repair of cement fractures in wellbore (and other) systems is the injection of polymer materials into the fracture with a subsequent environmentally dependent (temperature, pressure, pH, etc.) densification or solidification. Here, we aim to investigate novel polymer materials for use to repair leaking wellbores in the context of CCUS. We synthesize and fully characterize a series of novel polymer materials and utilize a suite of analysis techniques to examine polymer-cement interactions at a range of conditions (namely temperature, pressure and pH). Initial findings will be leveraged to design novel polymer materials for further evaluation in polymer-cement composite cores, cement fracture healing, and the aging behavior of healed cements.
Geology of the Southern Utopia Planitia Highland-Lowland Boundary Plain: Second Year Results and Third Year Plan

Science.gov (United States)

Skinner, J. A., Jr.; Tanaka, K. L.; Hare, T. M.

2009-01-01

The southern Utopia highland-lowland boundary (HLB) extends >1500 km westward from Hyblaeus Dorsa to the topographic saddle that separates Isidis and Utopia Planitiae. It contains bench-like platforms that contain depressions, pitted cones (some organized into arcuate chains and thumb-print terrain), isolated domes, buried circular depressions, ring fractures, polygonal fractures, and other locally- to regionally-dispersed landforms [1-2]. The objective of this map project is to clarify the geologic evolution of the southern Utopia Planitia HLB by identifying the geologic, structural, and stratigraphic relationships of surface materials in MTMs 10237, 15237, 20237, 10242, 15242, 20242, 10247, 15247, and 20247. The project was originally awarded in April, 2007 and is in its final year of support. Mapping is on-schedule and formal map submission will occur by December, 2009, with finalization anticipated by April, 2010. Herein, we (1) review specifics regarding mapping data and methods, (2) present nomenclature requests that we feel will assist with unit descriptions, (3) describe Year 2 mapping and science accomplishments, and (4) outline Year 3 technical and managerial approaches for finalizing the geologic map.
The Interior and Orbital Evolution of Charon as Preserved in Its Geologic Record

Science.gov (United States)

Rhoden, Alyssa Rose; Henning, Wade; Hurford, Terry A.; Hamilton, Douglas P.

2014-01-01

Pluto and its largest satellite, Charon, currently orbit in a mutually synchronous state; both bodies continuously show the same face to one another. This orbital configuration is a natural end-state for bodies that have undergone tidal dissipation. In order to achieve this state, both bodies would have experienced tidal heating and stress, with the extent of tidal activity controlled by the orbital evolution of Pluto and Charon and by the interior structure and rheology of each body. As the secondary, Charon would have experienced a larger tidal response than Pluto, which may have manifested as observable tectonism. Unfortunately, there are few constraints on the interiors of Pluto and Charon. In addition, the pathway by which Charon came to occupy its present orbital state is uncertain. If Charon's orbit experienced a high-eccentricity phase, as suggested by some orbital evolution models, tidal effects would have likely been more significant. Therefore, we determine the conditions under which Charon could have experienced tidally-driven geologic activity and the extent to which upcoming New Horizons spacecraft observations could be used to constrain Charon's internal structure and orbital evolution. Using plausible interior structure models that include an ocean layer, we find that tidally-driven tensile fractures would likely have formed on Charon if its eccentricity were on the order of 0.01, especially if Charon were orbiting closer to Pluto than at present. Such fractures could display a variety of azimuths near the equator and near the poles, with the range of azimuths in a given region dependent on longitude; east-west-trending fractures should dominate at mid-latitudes. The fracture patterns we predict indicate that Charon's surface geology could provide constraints on the thickness and viscosity of Charon's ice shell at the time of fracture formation.
Proceedings of the workshop on numerical modeling of thermohydrological flow in fractured rock masses

International Nuclear Information System (INIS)

1980-09-01

Nineteen papers were presented at the workshop on modeling thermohydrologic flow in fractured masses. This workshop was a result of the interest currently being given to the isolation of nuclear wastes in geologic formations. Included in these proceedings are eighteen of the presentations, one abstract and summaries of the panel discussions. The papers are listed under the following categories: introduction; overviews; fracture modelings; repository studies; geothermal models; and recent developments. Eighteen of the papers have been abstracted and indexed
An optimal design of cluster spacing intervals for staged fracturing in horizontal shale gas wells based on the optimal SRVs

Directory of Open Access Journals (Sweden)

Lan Ren

2017-09-01

Full Text Available When horizontal well staged cluster fracturing is applied in shale gas reservoirs, the cluster spacing is essential to fracturing performance. If the cluster spacing is too small, the stimulated area between major fractures will be overlapped, and the efficiency of fracturing stimulation will be decreased. If the cluster spacing is too large, the area between major fractures cannot be stimulated completely and reservoir recovery extent will be adversely impacted. At present, cluster spacing design is mainly based on the static model with the potential reservoir stimulation area as the target, and there is no cluster spacing design method in accordance with the actual fracturing process and targets dynamic stimulated reservoir volume (SRV. In this paper, a dynamic SRV calculation model for cluster fracture propagation was established by analyzing the coupling mechanisms among fracture propagation, fracturing fluid loss and stress. Then, the cluster spacing was optimized to reach the target of the optimal SRVs. This model was applied for validation on site in the Jiaoshiba shale gasfield in the Fuling area of the Sichuan Basin. The key geological engineering parameters influencing the optimal cluster spacing intervals were analyzed. The reference charts for the optimal cluster spacing design were prepared based on the geological characteristics of south and north blocks in the Jiaoshiba shale gasfield. It is concluded that the cluster spacing optimal design method proposed in this paper is of great significance in overcoming the blindness in current cluster perforation design and guiding the optimal design of volume fracturing in shale gas reservoirs. Keywords: Shale gas, Horizontal well, Staged fracturing, Cluster spacing, Reservoir, Stimulated reservoir volume (SRV, Mathematical model, Optimal method, Sichuan basin, Jiaoshiba shale gasfield
Numerical simulations of heat transfer through fractured rock for an enhanced geothermal system development in Seokmodo, Korea

Science.gov (United States)

Shin, Jiyoun; Kim, Kyung-Ho; Hyun, Yunjung; Lee, Kang-Keun

2010-05-01

Estimating the expected capacity and efficiency of energy is a crucial issue in the construction of geothermal plant. It is the lasting temperature of extracted geothermal water that determines the effectiveness of enhanced geothermal systems (EGS), so the heat transfer processes in geothermal reservoirs under site-specific geologic conditions should be understood first. The construction of the first geothermal plant in Korea is under planning in Seokmodo, where a few flowing artesian wells showing relatively high water temperature of around 70°C were discovered lately. The site of interest is a part of the island region, consisting of the reclaimed land surrounded by the sea and small mountains. Geothermal gradient measures approximately 45°C/km and the geothermal water is as saline as seawater. Geologic structure in this region is characterized by the fractured granite. In this study, thermo-hydrological (TH) numerical simulations for the temperature evolution in a fractured geothermal reservoir under the supposed injection-extraction operating conditions were carried out using TOUGH2. Multiple porosity model which is useful to calculate the transient interporosity flow in TH coupled heat transfer problem was used in simulations. Several fracture planes which had been investigated in the field were assigned to have highly permeable properties in order to avoid the averaging approximation and describe the dominant flow through the fractures. This heterogeneous model showed the rise of relatively hot geothermal water in the densely fractured region. The temperature of the extracted geothermal water also increased slowly for 50 years due to the rising flow through the fractures. The most sensitive factor which affects the underground thermal distribution and temperature of geothermal water was permeability of the medium. Change in permeabilities of rock and fracture within the range of 1 order might cause such an extreme change in the temperature of geothermal

A multi-packer technique for investigating resistance to flow through fractured rock and illustrative results

International Nuclear Information System (INIS)

Bourke, P.J.; Rae, J.

1981-01-01

A multi-packer technique was used to locate twelve discrete fractures in the lower half of a 200 m deep drill hole in Cornish granite. The resistances to water flows into these fractures both singly and together were measured. Geological explanations of the results obtained were sought by examination of core from the hole. Analysis of the results and the further data needed and now being sought to determine resistance to flow over long distances through the pattern of interconnected fractures are discussed. This information is required for the assessment of the safety of burial of radioactive wastes
Geological Geophysical and structural studies in Mina Ratones (Pluton de Albala); Estudios geologico-estructurales y geofisicos en Mina Ratones (Pluton de Albala)

Energy Technology Data Exchange (ETDEWEB)

Perez-Estaun, A; Carbonell, R; Marti, D; Flecha, I [Instituto de Ciencias de la Tierra Jaume Almera. Barcelona (Spain); Escuder Viruete, J [Universidad complutense de Madrid. Madrid (Spain)

2002-07-01

Mina Ratones environmental restoration project included petrological, structural,geophysical, hydrogeological and hydrogeochemical studies. The main objective of the geologic-structural and geophysical studies was the Albala granite structural characterization around the Mina Ratones uranium mine. The location of facies, fault zones (faults and dykes) as well as the distribution of some physical properties inside the rock massif was obtained for a granitic black of 900, 500, and 500 m. The geologic-structural and geophysical techniques applied to Mina Ratones provided a multidisciplinary approach for high resolution characterization of rock massif, and the structures potentially containing fluids,able to be applied to the hydrogeological modelling to a particular area. Geological studies included a detailed structural mapping of the area surrounding the mine (1:5,000 scale), the geometric, kinematics, and dynamics analysis of fractures of all scales, the petrology and geochemistry of fault rocks and altered areas surrounding fractures, and the microstructural studies of samples from surface and core lags. The construction of geostatistical models in two and three dimensions had helped to characterize the Mina Ratones rock massif showing the spatial distribution of fault zones, fracture intensity, granite composition heterogeneities, fluid-rock interaction zones, and physical properties. (Author)
Effects of different block size distributions in pressure transient response of naturally fractured reservoirs

Energy Technology Data Exchange (ETDEWEB)

Montazeri, G.H. [Islamic Azad University, Mahshahr (Iran, Islamic Republic of). Dept. of Chemical and Petroleum Engineering], E-mail: montazeri_gh@yahoo.com; Tahami, S.A. [Mad Daneshgostar Tabnak Co. (MDT),Tehran (Iran, Islamic Republic of); Moradi, B.; Safari, E. [Iranian Central Oil Fields Co, Tehran (Iran, Islamic Republic of)], E-mail: morady.babak@gmail.com

2011-07-15

This paper presents a model for pressure transient and derivative analysis for naturally fractured reservoirs by a formulation of inter porosity flow incorporating variations in matrix block size, which is inversely related to fracture intensity. Geologically realistic Probability Density Functions (PDFs) of matrix block size, such as uniform, bimodal, linear and exponential distributions, are examined and pseudo-steady-state and transient models for inter porosity flow are assumed. The results have been physically interpreted, and, despite results obtained by other authors, it was found that the shape of pressure derivative curves for different PDFs are basically identical within some ranges of block size variability, inter porosity skin, PDFs parameters and matrix storage capacity. This tool can give an insight on the distribution of block sizes and shapes, together with other sources of information such as Logs and geological observations. (author)
Microbially Induced Calcite Precipitation (MICP) - A Technology for Managing Flow and Transport in Porous and Fractured Media

Science.gov (United States)

Phillips, A. J.; Hiebert, R.; Kirksey, J.; Lauchnor, E. G.; Rothman, A.; Spangler, L.; Esposito, R.; Gerlach, R.; Cunningham, A. B.

2014-12-01

Certain microorganisms e.g., Sporosarcina pasteurii contribute enzymes that catalyze reactions which in the presence of calcium, can create saturation conditions favorable for calcium carbonate precipitation (microbially-induced calcium carbonate precipitation (MICP)). MICP can be used for a number of engineering applications including securing geologic storage of CO2 or other fluids by sealing fractures, improving wellbore integrity, and stabilizing fractured and unstable porous media. MICP treatment has the advantage of the use of small microorganisms, ~2μm, suggesting applicability to treatment of small aperture fractures not accessible to traditional treatments, for example the use of fine cement. The promotion of MICP in the subsurface is a complex reactive transport problem coupling microbial, abiotic (geochemical), geomechanical and hydrodynamic processes. In the laboratory, MICP has been demonstrated to cement together heavily fractured shale and reduce the permeability of fractures in shale and sandstone cores up to five orders of magnitude under both ambient and subsurface relevant pressure conditions (Figure 1). Most recently, a MICP fracture treatment field study was performed at a well at the Southern Company Gorgas Steam Generation Plant (Alabama) (Figure 1). The Fayetteville Sandstone at approximately 1120' below ground surface was hydraulically fractured prior to MICP treatment. After 4 days of injection of 24 calcium pulses and 6 microbial inoculations, injectivity of brine into the formation was significantly reduced. The experiment also resulted in a reduction in pressure decay which is a measure of improved wellbore integrity. These promising results suggest the potential for MICP treatment to seal fractured pathways at the field scale to improve the long-term security of geologically-stored carbon dioxide or prevent leakage of shale gas or hydraulic fracturing fluids into functional overlying aquifers, reducing environmental impacts.
An appraisal of the geologic structure beneath the Ikogosi warm spring in south-western Nigeria using integrated surface geophysical methods

Directory of Open Access Journals (Sweden)

J.S Ojo

2011-06-01

Full Text Available An integrated surface geophysical investigation involving resistivity and magnetic methods was carried out in the immediate vicinity of the Ikogosi warm spring situated in south-western Nigeria with a view to delineating its subsurface geological sequence and evaluating the structural setting beneath the warmspring. Total field magnetic measurements and vertical electrical sounding (VES data were acquired along five N-S traverses. Magnetic and VES data interpretation
involved inverse modelling. The inverse magnetic models delineated fractured quartzite/faulted areas within fresh massive quartzite at varying depths and beneath all traverses. The geoelectrical sections developed from VESinterpretation results also delineated a subsurface sequence consisting of a topsoil/weathered layer, fresh quartzite, fractured/faulted quartzite and fresh quartzite bedrock. It was deduced that the fractured/faulted quartzite may have acted as conduit for the
movement of warm groundwater from profound depths to the surface while the spring outlet was located on a geological interface (lineament.
Numerical modelling of coupled fluid, heat, and solute transport in deformable fractured rock

International Nuclear Information System (INIS)

Chan, T.; Reid, J.A.K.

1987-01-01

This paper reports on a three-dimensional (3D) finite-element code, MOTIF (model of transport in fractured/porous media), developed to model the coupled processes of groundwater flow, heat transport, brine transport, and one-species radionuclide transport in geological media. Three types of elements are available: a 3D continuum element, a planar fracture element that can be oriented in any arbitrary direction in 3D space or pipe flow in 3D space, and a line element for simulating fracture flow in 2D space or pipe flow in 3D space. As a quality-assurance measure, the MOTIF code was verified by comparison of its results with analytical solutions and other published numerical solutions
Data of fractures based on the deep borehole investigations in the Horonobe Underground Research Laboratory project. Phase 1

International Nuclear Information System (INIS)

Kusano, Tomohiro; Ishii, Eiichi

2016-02-01

Japan Atomic Energy Agency (JAEA) is performing the Horonobe Underground Research Laboratory Project, which includes a scientific study of the deep geological environment as a basis of research and development for geological disposal of high level radioactive wastes (HLW), in order to establish comprehensive techniques for the investigation, analysis and assessment of the deep geological environment in the sedimentary rock. This report aims at compiling fracture data of drill core obtained from the Horonobe Underground Research Laboratory Project (Phase 1). (author)
Localizing Fracture Hydromechanical Response using Fiber Optic Distributed Acoustic Sensing in a Fractured Bedock Aquifer

Science.gov (United States)

Ciervo, C.; Becker, M.; Cole, M. C.; Coleman, T.; Mondanos, M.

2017-12-01

Measuring fracture mechanical behavior in response to changes in fluid pressure is critical for understanding flow through petroleum reservoirs, predicting hydrothermal responses in geothermal fields, and monitoring geologic carbon sequestration injection. Distributed acoustic sensing (DAS) is new, but commercially available fiber optic technology that offers a novel approach to characterize fractured bedrock systems. DAS was originally designed to measure the amplitude, frequency, and phase of an acoustic wave, and is therefore capable of detecting strains at exceedingly small scales. Though normally used to measure frequencies in the Hz to kHz range, we adapted DAS to measure fracture displacements in response to periodic hydraulic pulses in the mHz frequency range. A field experiment was conducted in a fractured bedrock aquifer to test the ability of DAS to measure fracture mechanical response to oscillatory well tests. Fiber optic cable was deployed in a well, and coupled to the borehole wall using a flexible impermeable liner designed with an air coupled transducer to measure fluid pressure at the target fracture zone. Two types of cable were tested, a loose tube and tight buffered, to determine the effects of cable construction. Both strain and pressure were measured across the known fracture zone hydraulically connected to a well 30 m away. The companion well was subjected to alternating pumping and injection with periods between 2 and 18 minutes. Raw DAS data were collected as strain rate measured every 0.25 m along the fiber with a gauge length of 10 m, at a sampling rate of 1 kHz. Strain rate was converted to strain by integrating with respect to time. DAS measured periodic strains of less than 1 nm/m in response to periodic injection and pumping at the companion well. Strain was observed by DAS only at the depth of the hydraulically connected fracture zone. Thus, the magnitude and response of the strain could be both localized with depth and measured
Fracture analysis for engineering geological utilization

Energy Technology Data Exchange (ETDEWEB)

Choi, H I; Choi, P Y; Hong, S H; Chi, K H; Kim, J Y; Lee, S R; Lee, S G; Park, D W; Han, J G [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

1997-12-01

The problem of geological hazards (earthquakes) and water or thermal resources urges us to understand the regional tectonic setting or recent tectonics. The Uisong Subbasin is located in one of the seismicity zones in Korea. Because the reactivity of the Gaeum Fault System is an important problem focussing on these faults, we studied their whole extension and timing of faulting in terms of tectonics. Fault tectonic analysis is so effective as to easily reconstruct the tectonic sequence and each stress state at each site, eventually in a region. One can get insights for faulting timing in terms of the restored tectonic sequence, and discriminating the active faults or the faults active in the last (present) tectonics. Examining the filling materials in tension gashes, one can get raw knowledge regarding the thermal states at each site. For this study, we first analyzed the topographic textures (lineament, drainage and circular structures) on the relief map produced based on the topographic maps of 1:100,000 scale. Through investigations of susceptible area along the faults, their existence and movement modes were studied, and we can get information about movement history and whole extension of the faults belonging to the WNW-ESE trending Gaeum Fault System. In order to reconstruct the tectonic sequence, we measured fault slip data, tension gashes and dikes, from which fault populations were classified and stress (and thermal) states were determined. Seven compressional tectonic events and six extensional events were reconstructed. Because coaxial events partially coexisted, we bundled these events in one, finally we get seven tectonic events. Determining the types of minerals filling the tension gashes, we suggested the possibility of investigation of geothermal resources with less efforts. (author). 162 refs., 14 tabs., 51 figs.
The use of multifrequency and polarimetric SIR-C/X-SAR data in geologic studies of Bir Safsaf, Egypt

Science.gov (United States)

Schaber, G.G.; McCauley, J.F.; Breed, C.S.

1997-01-01

Bir Safsaf, within the hyperarid 'core' of the Sahara in the Western Desert of Egypt, was recognized following the SIR-A and SIR-B missions in the 1980s as one of the key localities in northeast Africa, where penetration of dry sand by radar signals delineates previously unknown, sand-buried paleodrainage valleys ('radar-rivers') of middle Tertiary to Quaternary age. The Bir Safsaf area was targeted as a focal point for further research in sand penetration and geologic mapping using the multifrequency and polarimetric SIR-C/X-SAR sensors. Analysis of the SIR-C/X-SAR data from Bir Safsaf provides important new information on the roles of multiple SAR frequency and polarimetry in portraying specific types of geologic units, materials, and structures mostly hidden from view on the ground and on Landsat TM images by a relatively thin, but extensive blanket of blow sand. Basement rock units (granitoids and gneisses) and the fractures associated with them at Bir Safsaf are shown here for the first time to be clearly delineated using C- and L-band SAR images. The detectability of most geologic features is dependent primarily on radar frequency, as shown for wind erosion patterns in bedrock at X-band (3 cm wavelength), and for geologic units and sand and clay-filled fractures in weathered crystal-line basement rocks at C-band (6 cm) and L-band (24 cm). By contrast, Quaternary paleodrainage channels are detectable at all three radar frequencies owing, among other things, to an usually thin cover of blow sand. The SIR-C/X-SAR data investigated to date enable us to make specific recommendations about the utility of certain radar sensor configurations for geologic and paleoenvironmental reconnaissance in desert regions.Analysis of the shuttle imaging radar-C/X-synthetic aperture radar (SIR-C/X-SAR) data from Bir Safsaf provides important new information on the roles of multiple SAR frequency and polarimetry in portraying specific types of geologic units, materials, and
Geological And Geotechnical Investigations Of Axum Dam Site Tigray Northern Ethiopia

Directory of Open Access Journals (Sweden)

Leulalem

2015-08-01

Full Text Available Geological and geotechnical study was conducted in concrete gravity dam which is planned to be constructed in the Maychew River 40 km south of Axum town for the purpose of water supply for the town. The objectives of this research were to map geology of the area to characterize geological defects within and around dam site to evaluate the water tightness of the dam site and to determine the bearing capacity of the dam foundation. The research involved review of different literatures lithological and structural mapping characterizing rock masses by using different rock mass classification methods interpretation of subsurface data geophysical core drilled data test pit data etc.. Results of the study indicate that the area is underlain by Quaternary sediments metasedimentary and metavolcanic rocks. The Quaternary sediments are characterized by low permeability low plasticity and are poorly graded nature. Metasedimentary rocks are found covering the right abutment of the dam whereas at reservoir area it is found intercalating with metavolcanic rocks. These rocks are moderately jointed and sheared with faulting and folding noticed due to these they have a relatively high permeability. Metavolcanic rocks which are found covering the left abutment are strong less permeable and fractured. Most of discontinuities such as fractures bedding and foliation in the study area are oriented E-W NNW-SSE and NNE-SSW. The VES tomography and drilled core result revealed that the potential problems seepageleakage could occur due to presence of faults joints karstified black limestone lithological variations groundwater depth and topography at right abutment. Differential settlements may also occur because empirically estimated moduli of deformation Ed of rock masses indicate that for right abutment much less than left abutment and different geological defects across the dam axis. To minimize these problems contact grouting and consolidation grouting are recommended
Naturally fractured tight gas reservoir detection optimization. Annual report, September 1993--September 1994

Energy Technology Data Exchange (ETDEWEB)

NONE

1994-10-01

This report is an annual summarization of an ongoing research in the field of modeling and detecting naturally fractured gas reservoirs. The current research is in the Piceance basin of Western Colorado. The aim is to use existing information to determine the most optimal zone or area of fracturing using a unique reaction-transport-mechanical (RTM) numerical basin model. The RTM model will then subsequently help map subsurface lateral and vertical fracture geometries. The base collection techniques include in-situ fracture data, remote sensing, aeromagnetics, 2-D seismic, and regional geologic interpretations. Once identified, high resolution airborne and spaceborne imagery will be used to verify the RTM model by comparing surficial fractures. If this imagery agrees with the model data, then a further investigation using a three-dimensional seismic survey component will be added. This report presents an overview of the Piceance Creek basin and then reviews work in the Parachute and Rulison fields and the results of the RTM models in these fields.
Fracture network created by 3D printer and its validation using CT images

Science.gov (United States)

Suzuki, A.; Watanabe, N.; Li, K.; Horne, R. N.

2017-12-01

Understanding flow mechanisms in fractured media is essential for geoscientific research and geological development industries. This study used 3D printed fracture networks in order to control the properties of fracture distributions inside the sample. The accuracy and appropriateness of creating samples by the 3D printer was investigated by using a X-ray CT scanner. The CT scan images suggest that the 3D printer is able to reproduce complex three-dimensional spatial distributions of fracture networks. Use of hexane after printing was found to be an effective way to remove wax for the post-treatment. Local permeability was obtained by the cubic law and used to calculate the global mean. The experimental value of the permeability was between the arithmetic and geometric means of the numerical results, which is consistent with conventional studies. This methodology based on 3D printed fracture networks can help validate existing flow modeling and numerical methods.
Fracture network created by 3-D printer and its validation using CT images

Science.gov (United States)

Suzuki, Anna; Watanabe, Noriaki; Li, Kewen; Horne, Roland N.

2017-07-01

Understanding flow mechanisms in fractured media is essential for geoscientific research and geological development industries. This study used 3-D printed fracture networks in order to control the properties of fracture distributions inside the sample. The accuracy and appropriateness of creating samples by the 3-D printer was investigated by using a X-ray CT scanner. The CT scan images suggest that the 3-D printer is able to reproduce complex three-dimensional spatial distributions of fracture networks. Use of hexane after printing was found to be an effective way to remove wax for the posttreatment. Local permeability was obtained by the cubic law and used to calculate the global mean. The experimental value of the permeability was between the arithmetic and geometric means of the numerical results, which is consistent with conventional studies. This methodology based on 3-D printed fracture networks can help validate existing flow modeling and numerical methods.
Geological mapping of investigation Trench OL-TK13 at the Olkiluoto study site, Eurajoki, SW Finland

International Nuclear Information System (INIS)

Talikka, M.

2007-04-01

Geological mapping of investigation trench OL-TK13 was carried out by the Geological Survey of Finland at the Olkiluoto study site, Eurajoki, as a part Posiva Oy's site investigation programme for the development of an underground repository for nuclear waste. The east-west striking, ca. 250 m long trench is located in the vicinity of boreholes OL-KR23 and OL-KR27, ca. 250 m east of the ONKALO research facility. The mapping was performed from washed bedrock surface and rock types were determined macroscopically. The main rock types in OL-TK13 are diatexitic gneiss, veined gneiss, pegmatitic granite and K-feldspar porphyry. Mica gneiss and granite/granitized mica gneiss exist to a lesser extent. The diatexitic gneiss is the dominant rock type in the western part and the veined gneiss in the eastern part of the trench. The veined gneiss consists of pelitic mica gneiss paleosome and pegmatitic granite leucosome veins that are parallel to the foliation. In the diatexitic gneiss, the proportion of the leucosome veins and patches is over 50 % and the rock has an ambiguous texture. The pegmatitic granite also occurs as wider sections in the western part of the trench. The K-feldspar porphyry is characterized by potassium feldspar phenocrysts (diameter 4 deformation phase. The migmatitic gneisses were folded during the D 3 deformation phase resulting in small scale, tight and asymmetrical F 3 folds plunging moderately to the NE. During the fracture mapping, all fractures longer than one metre and all fractures intersecting the central thread were investigated. Measurements including orientation, length, fillings, Jr-value, Ja-value and undulation were recorded for a total of 860 fractures. The mean fracture density is 3.5 fracture/m. From the orientation data, three fracture sets were identified: (1) fractures parallel to the foliation, (2) subvertical N-S trending factures and (3) fractures dipping steeply to the N. ∼45 % of all fractures are 0.5-1.5 m in length and �
Results from the geological surveys carried out in the Bure laboratory's shafts

International Nuclear Information System (INIS)

Rebours, Herve; Righini, Celine

2010-01-01

Document available in extended abstract form only. After the government's authorization to build and operate an underground laboratory, Andra started the investigation works in November 99 on the Meuse/Haute-Marne URL site. The Meuse/Haute-Marne URL is located at the border of the Champagne-Ardenne and Lorraine regions, on the township of Bure in the Callovo-Oxfordian clay-rich rock. On the URL site, the layer is about 135 m-thick and lies at a depth of 417 m to 552 m. The laboratory consists of two levels of experimental drifts at depths of 445 m and 490 m, respectively, with two vertical shafts crossing the 505 m-thick sedimentary cover of Kimeridgian (about 100 meters of marls and limestones), Oxfordian (about 300 meters of limestones) and Callovo-Oxfordian formations. The construction of the underground installations started in August 2000 with the sinking of the main shaft and was completed on the 27 April 2006 when it linked up with the southern drift of the laboratory. The two access shafts are sunk with a drill and blast method with steps of 2.4 to 3.1 m. A temporary support with grouted bolts and wire mesh is set immediately after the blasting and removal of the muck. The definitive concrete lining is installed about 12 to 20 m behind the face. The excavated diameter of the main shaft where the geological surveys and experiments have been undertaken is of 6 m (5 m after lining). The second shaft (auxiliary shaft for the ventilation of the URL) is sunk in a smaller diameter (5 m). The aims of the geological surveys carried out during the shaft sinking are to describe the vertical and lateral (between the two shafts) variations of the lithology, to confirm the absence of fault and the geometry of the argillaceous rocks formation. These surveys allow to characterize the natural or inducted fracturing by a sedimentary and structural follow-up of the excavation face. This follow-up was carried out every 2.4 to 3.0 meters in the shafts. During the shaft
Geologic environmental study

International Nuclear Information System (INIS)

Kim, Chun Soo; Bae, Dae Seok; Kim, Kyung Su; Park, Byung Yoon; Koh, Young Kown; Chun, Kwan Sik; Kim, Jhin Wung

2000-05-01

The geoscience research works are focused on the production of geologic basic data accompanying with the technical development of geology and hydrogeologic characterization. The lithology of the Korean peninsula consists of a complex structure of 29 rock types from Archean to Quaternary. The wide distribution of Mesozoic plutonic rock is an important consideration as a potential host rock allowing flexibility of siting. The recent tectonic activities are limited to localized particular area, which can be avoided by excluding in the early stage of siting. Three rock types such as plutonic rocks, crystalline gneisses and massive volcanic rocks were suggested as the preferred host rocks for the further study on HLW disposal system. This report contains grouping of regional faults, and on the distributional characteristics of faults and fractures(zones) in terms of lithological domain and tectonical provinces. The regional groundwater regime can be grouped into 3 regimes by tectonic setting and four groundwater regions based on an altitute. Groundwaters can be grouped by their chemistry and host rocks. The origin of groundwater was proposed by isotope ( 1 8O, 2 H, 1 3C, 3 4S, 8 7Sr, 1 5N) studies and the residence time of groundwater was inferred from their tritium contents. Based on the geochemical and isotope characteristics, the geochemical evolutions of each types of groundwater were simulated using SOLVEQ/CHILLER and PHREEQC programs
Selected visualizations and summaries of the contents of the fracture database, deformation zone intersection data, and deviation survey measurements regarding boreholes OL-KR1 - OL-KR33B

International Nuclear Information System (INIS)

Kuusisto, S.; Lehtokangas, M.

2007-02-01

Posiva Oy has acquired an extensive amount of data on the geology of the Olkiluoto Island. An important part of that data is the heterogeneous collection of fracture information, known as the fracture database. In this work, the fracture database was studied and analyzed using data mining techniques aiming to characterize the properties of the database itself, not the underlying geological and physical laws and phenomenona that are reflected through the data. The goal was to discover previously unknown correlations, patterns, and properties contained within the data. In addition to the fracture database, two supporting datasets were utilized in the analysis: deformation zone intersection data and deviation survey measurements. The following analyses were carried out: logical discrepancies and potential errors in data; statistics of alphanumeric strings, numeric values, and empty fields; visualizations of borehole locations and shapes; histograms, ranges, quantizations, 1- and 2- dimensional clustering of numeric quantities; core orientations; comparison between reported fracture orientations with those recalculated using the core orientations and fracture orientations with respect to core; fracture densities; fracture orientations at intersections of each deformation zone separately; statistics of zone intersection data; discovery of groups of valid fields in the database; discovery of quantities that predict the lithology or hydraulic conductivity of fractures; discovery of fracture fillings that have a tendency to appear together. The interpretation of the analysis results was beyond the scope of this work. The assessment of the novelty and the usefulness of the discovered patterns and relationships requires domain expertise and familiarity with the everyday practises on how the data is utilized, what assumptions are satisfied and which aspects are significant. Instead, this report gives numerous different viewpoints on the data and through them, brings up issues
Comparison of different modeling approaches to simulate contaminant transport in a fractured limestone aquifer

DEFF Research Database (Denmark)

Mosthaf, Klaus; Rosenberg, L.; Balbarini, Nicola

. Given available field data and model purpose, this paper therefore aims to develop, examine and compare modeling approaches for transport of contaminants in fractured limestone aquifers. The model comparison was conducted for a contaminated site in Denmark, where a plume of a dissolved contaminant (PCE...... was combined with an analysis of heterogeneities and fractures from a nearby excavation (analog site). Methods for translating the geological information and fracture mapping into each of the model concepts were examined. Each model was compared with available field data, considering both model fit...... of field data is the determination of relevant hydraulic properties and interpretation of aqueous and solid phase contaminant concentration sampling data. Traditional water sampling has a bias towards fracture sampling, however concentrations in the limestone matrix are needed for assessing contaminant...
Coupled Modeling of Flow, Transport, and Deformation during Hydrodynamically Unstable Displacement in Fractured Rocks

Science.gov (United States)

Jha, B.; Juanes, R.

2015-12-01

Coupled processes of flow, transport, and deformation are important during production of hydrocarbons from oil and gas reservoirs. Effective design and implementation of enhanced recovery techniques such as miscible gas flooding and hydraulic fracturing requires modeling and simulation of these coupled proceses in geologic porous media. We develop a computational framework to model the coupled processes of flow, transport, and deformation in heterogeneous fractured rock. We show that the hydrocarbon recovery efficiency during unstable displacement of a more viscous oil with a less viscous fluid in a fractured medium depends on the mechanical state of the medium, which evolves due to permeability alteration within and around fractures. We show that fully accounting for the coupling between the physical processes results in estimates of the recovery efficiency in agreement with observations in field and lab experiments.

To the question the unity of composition of fluids of heterogeneous geological objects.

Science.gov (United States)

Galant, Yuri

2017-04-01

Creation of Unit Theory Oil Generation based on a number of the provisions, one of which is the unity of the hydrocarbon composition in various geological objects. Studies conducted in various geological conditions and tectonic - magmatic environment. In studying the hydrocarbon composition of various geological objects, untraditional for petroleum geology (igneous rocks, metamorphic rocks, mineral deposits, etc.) progressively manifested that hydrocarbons are also distributed and have the following features. Studies have shown: 1. The composition of the hydrocarbon components presented by, light hydrocarbons, heavy hydrocarbons up to including hexane, normal forms, isoforms, saturated and unsaturated hydrocarbons. 2. Hydrocarbon composition and the ratio of methane to heavy hydrocarbons corresponds to the composition of gases gas fields. 3. The composition and the ratio of hydrocarbons do not depend on genetic types of heterogeneous geological objects. 4. Gas saturation meets the prevailing structure of rocks - pores or fractures. The foregoing allows us to speak of a single source of generating and delivering hydrocarbons in the Earth's Crust, regardless of the geological situation. I.e. the presence of hydrocarbons in the Earth's Crust is UNITED! 5. From a practical point of view - virtually unconventional for hydrocarbons rock can serve as unconventional hydrocarbon resources.
Analytical Modeling of the Pseudo-Colloid Migration with the Band release Boundary Condition in the Fractured Porous Media

International Nuclear Information System (INIS)

Jeong, Miseon; Kang, Chulhyung; Hwang, Yongsoo

2011-01-01

Many papers have already dealt with the problem of the radionuclide transport in various fractured porous systems, but without discussing daughter products. However, natural radionuclides may decay to radioactive daughter muscled, which may travel farther than the the parent nuclides. It is considered the multi-member decay chain of the actinide nuclide with the band release inlet boundary condition in a fractured porous rock. In this paper, it is developed the pseudo-colloid migration with the band release inlet boundary conditions with multi-member decay chains in a fractured porous matrix. It is obtained a semi-analytical solution for the multi-member decay chains as a canonical form. As one can expected, the colloid has significantly important influence to the radionuclide transport in the geologic system and the decay chain also isn't neglecting. The concept of deep geological disposal of high-level radioactive waste has been widely accepted at many countries. The repositories aim mainly to prevent the radionuclides form migrating to the biosphere through any one of many pathways. Fractures can act as main pathways for radionuclide transport because of their relatively high permeabilities
A Discrete Fracture Network Model with Stress-Driven Nucleation and Growth

Science.gov (United States)

Lavoine, E.; Darcel, C.; Munier, R.; Davy, P.

2017-12-01

The realism of Discrete Fracture Network (DFN) models, beyond the bulk statistical properties, relies on the spatial organization of fractures, which is not issued by purely stochastic DFN models. The realism can be improved by injecting prior information in DFN from a better knowledge of the geological fracturing processes. We first develop a model using simple kinematic rules for mimicking the growth of fractures from nucleation to arrest, in order to evaluate the consequences of the DFN structure on the network connectivity and flow properties. The model generates fracture networks with power-law scaling distributions and a percentage of T-intersections that are consistent with field observations. Nevertheless, a larger complexity relying on the spatial variability of natural fractures positions cannot be explained by the random nucleation process. We propose to introduce a stress-driven nucleation in the timewise process of this kinematic model to study the correlations between nucleation, growth and existing fracture patterns. The method uses the stress field generated by existing fractures and remote stress as an input for a Monte-Carlo sampling of nuclei centers at each time step. Networks so generated are found to have correlations over a large range of scales, with a correlation dimension that varies with time and with the function that relates the nucleation probability to stress. A sensibility analysis of input parameters has been performed in 3D to quantify the influence of fractures and remote stress field orientations.
The geological basis and the representation of spatial variability in fractured media

International Nuclear Information System (INIS)

Mazurek, M.; Gautschi, A.; Zuidema, P.

1998-01-01

Spatial variability of features and parameters relevant for contaminant transport modelling occurs on all scales of interest for the quantification of processes that govern solute migration, typically decimeters to hundreds of meters. Two types of spatial variability are distinguished, namely the internal heterogeneity of each individual water-conducting feature (e.g. the complex architecture of a fault) and the larger-scale heterogeneity that results from the groundwater flow through different types of water-conducting features along the flow-path from the repository to the discharge areas. An up-scaling procedure is required to obtain hydraulic parameters and the properties of the overall flow-path, whereas the heterogeneity of many other geologic features (geometry of flow and matrix porosity, mineralogy, etc.) can be fed directly into coupled codes that quantify radionuclide transport. The procedures needed to derive conceptual models integrating geological and hydraulic field measurements and observations at a given site are illustrated by examples from both crystalline and sedimentary rock formations. (author)
Suitability of ground penetrating radar for locating large fractures

Energy Technology Data Exchange (ETDEWEB)

Heikkinen, E. [Poeyry Finland Oy, Vantaa (Finland); Kantia, P. [Roadscanners Oy, Rovaniemi (Finland)

2011-12-15

Posiva Oy is responsible for preparation of final disposal of spent nuclear fuel in Olkiluoto. The knowledge about existing network of fractures is important for the safety and feasibility of the final repository. The bedrock properties essential for safety case are analysed in investigations of Rock Suitability Criteria (RSC). One subtask in RSC is avoidance of large (long) fractures adjacent to disposal holes. The long fractures have been defined in tunnel mapping to indicate tunnel cross-cutting features (TCF) or full perimeter intersections (FPI). Suitability of ground penetrating radar (GPR) method for locating large fractures was assessed. The assessment used data measured with 100 MHz and 270 MHz radar tool on ONKALO access tunnel right-hand wall, chainage 3344 - 3578 and on TKU-3 niche floor chainage 15 - 55 and 25 - 67 m. GPR images were processed to enhance reflections and suppress interference and diffractions. Images were placed on measurement position in 3D presentation software. The tunnel wall and floor mapping data was presented along with GPR images. A review of observed GPR reflections, and assessment of visibility of large fractures, was drawn on basis of 3D view examination. The GPR tool can detect reflections from cleaned and dry rock floor and wall. Depth of penetration is 8-12 m for 270 MHz antenna. The antenna has high resolution. Coupling on rock surface is good, which suppresses ringing and interference. Penetration is 20-24 m for 100 MHz antenna, which has a trade off of higher interference due to weaker contact to surface caused by large antenna. There are observed many kind of reflecting surfaces and diffractors in the images, like for example lithological contacts and high grade shearing, and also fractures. Proper manner to apply the method is to use raw and processed images during geological mapping to confirm the origin of reflections. Reflections deemed to be caused by fractures are useful to be compiled to 3D model objects. The
Suitability of ground penetrating radar for locating large fractures

International Nuclear Information System (INIS)

Heikkinen, E.; Kantia, P.

2011-12-01

Posiva Oy is responsible for preparation of final disposal of spent nuclear fuel in Olkiluoto. The knowledge about existing network of fractures is important for the safety and feasibility of the final repository. The bedrock properties essential for safety case are analysed in investigations of Rock Suitability Criteria (RSC). One subtask in RSC is avoidance of large (long) fractures adjacent to disposal holes. The long fractures have been defined in tunnel mapping to indicate tunnel cross-cutting features (TCF) or full perimeter intersections (FPI). Suitability of ground penetrating radar (GPR) method for locating large fractures was assessed. The assessment used data measured with 100 MHz and 270 MHz radar tool on ONKALO access tunnel right-hand wall, chainage 3344 - 3578 and on TKU-3 niche floor chainage 15 - 55 and 25 - 67 m. GPR images were processed to enhance reflections and suppress interference and diffractions. Images were placed on measurement position in 3D presentation software. The tunnel wall and floor mapping data was presented along with GPR images. A review of observed GPR reflections, and assessment of visibility of large fractures, was drawn on basis of 3D view examination. The GPR tool can detect reflections from cleaned and dry rock floor and wall. Depth of penetration is 8-12 m for 270 MHz antenna. The antenna has high resolution. Coupling on rock surface is good, which suppresses ringing and interference. Penetration is 20-24 m for 100 MHz antenna, which has a trade off of higher interference due to weaker contact to surface caused by large antenna. There are observed many kind of reflecting surfaces and diffractors in the images, like for example lithological contacts and high grade shearing, and also fractures. Proper manner to apply the method is to use raw and processed images during geological mapping to confirm the origin of reflections. Reflections deemed to be caused by fractures are useful to be compiled to 3D model objects. The
Geologic Map of the Diana Chasma Quadrangle (V-37), Venus

Science.gov (United States)

Hansen, V.L.; DeShon, H.R.

2002-01-01

Introduction The Diana Chasma quadrangle (V-37), an equatorial region between 0° to 25° S. and 150° to 180° E. that encompasses ~8,400,000 km2, is broadly divided into southern Rusalka Planitia in the north, eastern Aphrodite Terra in the central region, and unnamed regions to the south. Geologic mapping constrains the temporal and spatial relations of the major features, which include a tessera inlier, Markham crater, six large coronae (300-675 km diameter), four smaller coronae (150-225 km diameter), Diana and Dali chasmata, a large fracture zone, and southern Rusalka Planitia. Eastern Aphrodite Terra, marked here by large coronae, deep chasmata, and an extensive northeast-trending fracture zone, extends from Atla Regio to Thetis Regio. The large coronae are part of a chain of such features that includes Inari Corona to the west-southwest and Zemina Corona to the northeast. V-37 quadrangle is bounded on the north by Rusalka Planitia and on the south by Zhibek Planitia. International Astronomical Union (IAU) approved and provisional nomenclature and positions for geographic features within Diana Chasma quadrangle are shown on the geologic map. [Note: Atahensik Corona was referred to as Latona Corona in much previously published literature.
Spatial analysis of geologic and hydrologic features relating to sinkhole occurrence in Jefferson County, West Virginia

Science.gov (United States)

Doctor, Daniel H.; Doctor, Katarina Z.

2012-01-01

In this study the influence of geologic features related to sinkhole susceptibility was analyzed and the results were mapped for the region of Jefferson County, West Virginia. A model of sinkhole density was constructed using Geographically Weighted Regression (GWR) that estimated the relations among discrete geologic or hydrologic features and sinkhole density at each sinkhole location. Nine conditioning factors on sinkhole occurrence were considered as independent variables: distance to faults, fold axes, fracture traces oriented along bedrock strike, fracture traces oriented across bedrock strike, ponds, streams, springs, quarries, and interpolated depth to groundwater. GWR model parameter estimates for each variable were evaluated for significance, and the results were mapped. The results provide visual insight into the influence of these variables on localized sinkhole density, and can be used to provide an objective means of weighting conditioning factors in models of sinkhole susceptibility or hazard risk.
Proterozoic to Quaternary events of fracture mineralisation and oxidation in SE Sweden

International Nuclear Information System (INIS)

Drake, Henrik

2008-12-01

Fracture minerals and altered wall rock have been analysed to reveal the low-temperature evolution, especially regarding redox conditions, of the Simpevarp area, SE Sweden. This area is one of the two areas in Sweden investigated by the Swedish Nuclear fuel and Waste Management Co. in order to find a potential geological repository for spent nuclear fuel. The 1.8 Ga granitic to dioritic rocks in the area are generally un-metamorphosed and structurally well-preserved, although low-grade ductile shear zones and repeatedly reactivated fractures exist. Investigations of cross-cutting fractures along with a wide variety of fracture mineral analyses, such as stable isotopes and 40Ar/39Ar geochronology, have been used to distinguish a sequence of fracture filling generations. The characteristics of these generations indicate the low-temperature evolution of the area, including information of e.g. fluid origin, formation temperature, paleo stresses and relation to known geological events. Knowledge of the fracture mineral evolution is important for the conceptual geological and hydrogeochemical understanding of the site and supports predictions of future scenarios in the safety assessment. The fracture mineral generations identified have been formed at widely varying conditions starting in the Proterozoic with formation from inorganic hydrothermal fluids, continuing in the Paleozoic with formation from lower temperature brine type fluids with organic influence, and ranging into minerals formed from waters of varying salinity and with significant organic influence at conditions similar to the present conditions. However, the amount of potentially recent precipitates is very small compared to Proterozoic and Paleozoic precipitates. The fracture mineral parageneses have been associated, with varying confidence, to far-field effects of at least four different orogenies; the Svecokarelian orogeny (>1.75 Ga), the Danapolonian orogeny (∼1.47-1.44 Ga), the Sveconorwegian orogeny
Geological data acquisition for site characterisation at Olkiluoto: a framework for the phase of underground investigations

International Nuclear Information System (INIS)

Milnes, A.G.; Aaltonen, I.; Kemppainen, K.; Mattila, J.; Wikstroem, L.; Front, K.; Kaerki, A.; Gehoer, S.; Paulamaeki, S.; Paananen, M.; Ahokas, T.

2007-05-01

'Geological data acquisition' is a general term for the collection of observations and measurements by direct observation of exposed bedrock in the field (i.e. in natural outcrops and trenches, in drillholes, and in tunnels and other underground excavations). Only field-based data acquisition is included in this report: laboratory-based investigations will be continued, based on the field data and sampling, and all the data will be subject to discipline-specific processing, as the project proceeds. The ultimate aim of geological data acquisition is to provide the necessary data base for geological models of the bedrock of the Olkiluoto site, in connection with the construction of an underground rock characterisation facility, ONKALO, and a repository for spent nuclear fuel, at about 500m depth. Geological data acquisition plays a central role in site characterisation and modelling, and is intended to provide a solid platform on which the other disciplines (rock mechanics, hydrogeology, seismic risk assessment, etc.) can base their investigations. Based on consideration of a series of guidelines (e.g. modelling scale, source of data, level of investigation, national and international experience, special conditions at Olkiluoto, need for process understanding), a project-oriented 'framework' has been developed as a background to the different projects within the geological data acquisition programme. Each project will require its own system of data acquisition (methodology, spreadsheets, protocols, etc.), as described in the corresponding reports; the present report concentrates on the general principles which lie behind the different methodologies and data sheets. These principles are treated under three main headings: characterization of intact rock, characterization of deformation zone intersections, and characterization of individual fractures. Geological mapping of natural outcrops and trenches at Olkiluoto, and lithological logging of more than 40 rock cores
Advanced Hydraulic Fracturing Technology for Unconventional Tight Gas Reservoirs

Energy Technology Data Exchange (ETDEWEB)

Stephen Holditch; A. Daniel Hill; D. Zhu

2007-06-19

The objectives of this project are to develop and test new techniques for creating extensive, conductive hydraulic fractures in unconventional tight gas reservoirs by statistically assessing the productivity achieved in hundreds of field treatments with a variety of current fracturing practices ranging from 'water fracs' to conventional gel fracture treatments; by laboratory measurements of the conductivity created with high rate proppant fracturing using an entirely new conductivity test - the 'dynamic fracture conductivity test'; and by developing design models to implement the optimal fracture treatments determined from the field assessment and the laboratory measurements. One of the tasks of this project is to create an 'advisor' or expert system for completion, production and stimulation of tight gas reservoirs. A central part of this study is an extensive survey of the productivity of hundreds of tight gas wells that have been hydraulically fractured. We have been doing an extensive literature search of the SPE eLibrary, DOE, Gas Technology Institute (GTI), Bureau of Economic Geology and IHS Energy, for publicly available technical reports about procedures of drilling, completion and production of the tight gas wells. We have downloaded numerous papers and read and summarized the information to build a database that will contain field treatment data, organized by geographic location, and hydraulic fracture treatment design data, organized by the treatment type. We have conducted experimental study on 'dynamic fracture conductivity' created when proppant slurries are pumped into hydraulic fractures in tight gas sands. Unlike conventional fracture conductivity tests in which proppant is loaded into the fracture artificially; we pump proppant/frac fluid slurries into a fracture cell, dynamically placing the proppant just as it occurs in the field. From such tests, we expect to gain new insights into some of the critical
Flow channeling in a single fracture as a two-dimensional strongly heterogeneous permeable medium

International Nuclear Information System (INIS)

Tsang, Y.W.; Tsang, C.F.

1990-01-01

Recent interest in the evaluation of contaminant transport in bedrock aquifers and in the performance assessment of geologic nuclear waste repositories has motivated many studies of fluid flow and tracer transport in fractured rocks. Until recently, numerical modeling of fluid flow in the fractured medium commonly makes the assumption that each fracture may be idealized as a pair of parallel plates separated by a constant distance which represents the aperture of the fracture. More recent theoretical work has taken into account that the aperture in a real rock fracture in fact takes on a range of values. Evidence that flow in fractures tends to coalesce in preferred paths has been found in the field. Current studies of flow channeling in a fracture as a result of the variable apertures may also be applicable to flow and transport in a strongly heterogenous porous medium. This report includes the methodology used to study the flow channelling and tracer transport in a single fracture consisting of variable apertures. Relevant parameters that control flow channeling are then identified and the relationship of results to the general problem of flow in a heterogenous porous medium are discussed
Hydraulic conductivity of rock fractures

International Nuclear Information System (INIS)

Zimmerman, R.W.; Bodvarsson, G.S.

1994-10-01

Yucca Mountain, Nevada contains numerous geological units that are highly fractured. A clear understanding of the hydraulic conductivity of fractures has been identified as an important scientific problem that must be addressed during the site characterization process. The problem of the flow of a single-phase fluid through a rough-walled rock fracture is discussed within the context of rigorous fluid mechanics. The derivation of the cubic law is given as the solution to the Navier-Stokes equations for flow between smooth, parallel plates, the only fracture geometry that is amenable to exact treatment. The various geometric and kinetic conditions that are necessary in order for the Navier-Stokes equations to be replaced by the more tractable lubrication or Hele-Shaw equations are studied and quantified. Various analytical and numerical results are reviewed pertaining to the problem of relating the effective hydraulic aperture to the statistics of the aperture distribution. These studies all lead to the conclusion that the effective hydraulic aperture is always less than the mean aperture, by a factor that depends on the ratio of the mean value of the aperture to its standard deviation. The tortuosity effect caused by regions where the rock walls are in contact with each other is studied using the Hele-Shaw equations, leading to a simple correction factor that depends on the area fraction occupied by the contact regions. Finally, the predicted hydraulic apertures are compared to measured values for eight data sets from the literature for which aperture and conductivity data were available on the same fracture. It is found that reasonably accurate predictions of hydraulic conductivity can be made based solely on the first two moments of the aperture distribution function, and the proportion of contact area. 68 refs
Electromagnetic characterization of fractured rock for geological disposal studies of spent nuclear fuel

International Nuclear Information System (INIS)

Eloranta, E.; Ermutlu, M.; Flykt, M.; Lindell, I.; Nikoskinen, K.; Sihvola, A.

1998-04-01

In the report, the results of a joint research project carried out in 1991-1997 by the Finnish Radiation and Nuclear Safety Authority (STUK) and the Electromagnetics Laboratory of the Helsinki University of Technology are presented. The main purpose was to create computational models for electric potential responses when the medium is anisotropic and is bounded by a perfect magnetic conductor, a perfect electric conductor, and an anisotropic impedance surface. Furthermore, the geometry of two anisotropic half spaces and a layered medium were considered. The solutions of the problems were made using image theory. For modeling the electric potential in anisotropic medium with inhomogeneities, an integral equation was formulated. Also a wedge structure was treated as an extension to the traditional two parallel plate model of fracture geometry. The equivalentization of fracturing with anisotropy is a research area that still continues that still continues
A study on the characteristics of site-scale fracture system in granite and volcanic rock

Energy Technology Data Exchange (ETDEWEB)

Kim, Kyung Su; Kim, Chun Soo; Bae, Dae Seok; Park, Byoung Yoon; Koh, Young Kown [Korea Atomic Energy Research Institute, Taejeon (Korea)

2000-03-01

The safety of waste disposal can be achieved by a complete isolation of radioactive wastes from biosphere or by a retardation of nuclide migration to reach an acceptable dose level. For the deep geological disposal of high-level radioactive waste, the potential pathways of nuclide primarily depend on the spatial distribution characteristics of conductive fractures. Major key issues in the quantification of fracture system for a disposal site are involved in classification criteria, hydraulic parameters, geometry, field investigation methods etc. This research aims to characterize the spatial distribution characteristics of conductive fractures in granite and volcanic rock mass. 10 refs., 32 figs., 13 tabs. (Author)
Discrete Dual Porosity Modeling of Electrical Current Flow in Fractured Media

Science.gov (United States)

Roubinet, D.; Irving, J.

2013-12-01

The study of fractured rocks is highly important in a variety of research fields and applications such as hydrogeology, geothermal energy, hydrocarbon extraction, and the long-term storage of toxic waste. Fractured media are characterized by a large contrast in permeability between the fractures and the rock matrix. For hydrocarbon extraction, the presence of highly conductive fractures is an advantage as they allow for quick and easy access to the resource. For toxic waste storage, however, the fractures represent a significant drawback as there is an increased risk of leakage and migration of pollutants deep into the subsurface. In both cases, the identification of fracture network characteristics is a critical, challenging, and required step. A number of previous studies have indicated that the presence of fractures in geological materials can have a significant impact on geophysical electrical resistivity measurements. It thus appears that, in some cases, geoelectrical surveys might be used to obtain useful information regarding fracture network characteristics. However, existing geoelectrical modeling tools and inversion methods are not properly adapted to deal with the specific challenges of fractured media. This prevents us from fully exploring the potential of the method to characterize fracture network properties. We thus require, as a first step, the development of accurate and efficient numerical modeling tools specifically designed for fractured domains. Building on the discrete fracture network (DFN) approach that has been widely used for modeling groundwater flow in fractured rocks, we have developed a discrete dual-porosity model for electrical current flow in fractured media. Our novel approach combines an explicit representation of the fractures with fracture-matrix electrical flow exchange at the block-scale. Tests in two dimensions show the ability of our method to deal with highly heterogeneous fracture networks in a highly computationally
The Parabolic Variational Inequalities for Variably Saturated Water Flow in Heterogeneous Fracture Networks

Directory of Open Access Journals (Sweden)

Zuyang Ye

2018-01-01

Full Text Available Fractures are ubiquitous in geological formations and have a substantial influence on water seepage flow in unsaturated fractured rocks. While the matrix permeability is small enough to be ignored during the partially saturated flow process, water seepage in heterogeneous fracture systems may occur in a non-volume-average manner as distinguished from a macroscale continuum model. This paper presents a systematic numerical method which aims to provide a better understanding of the effect of fracture distribution on the water seepage behavior in such media. Based on the partial differential equation (PDE formulations with a Signorini-type complementary condition on the variably saturated water flow in heterogeneous fracture networks, the equivalent parabolic variational inequality (PVI formulations are proposed and the related numerical algorithm in the context of the finite element scheme is established. With the application to the continuum porous media, the results of the numerical simulation for one-dimensional infiltration fracture are compared to the analytical solutions and good agreements are obtained. From the application to intricate fracture systems, it is found that water seepage flow can move rapidly along preferential pathways in a nonuniform fashion and the variably saturated seepage behavior is intimately related to the geometrical characteristics orientation of fractures.
Analog site for fractured rock characterization. Annual report FY 1995

International Nuclear Information System (INIS)

Long, J.C.S.; Loughty, C.; Faybishenko, B.

1995-10-01

This report describes the accomplishments of the Analog Site for Fracture Rock Characterization Project during fiscal year 1995. This project is designed to address the problem of characterizing contaminated fractured rock. In order to locate contaminant plumes, develop monitoring schemes, and predict future fate and transport, the project will address the following questions: What parts of the system control flow-geometry of a fracture network? What physical processes control flow and transport? What are the limits on measurements to determine the above? What instrumentation should be used? How should it be designed and implemented? How can field tests be designed to provide information for predicting behavior? What numerical models are good predictors of the behavior of the system? The answers to these question can be used to help plan drilling programs that are likely to intersect plumes and provide effective monitoring of plume movement. The work is done at an open-quotes analogueclose quotes site, i.e., a site that is not contaminated, but has similar geology to sites that are contaminated, in order to develop tools and techniques without the financial, time and legal burdens of a contaminated site. The idea is to develop conceptual models and investigations tools and methodology that will apply to the contaminated sites in the same geologic regimes. The Box Canyon site, chosen for most of this work represents a unique opportunity because the Canyon walls allow us to see a vertical plane through the rock. The work represents a collaboration between the Lawrence Berkeley National Laboratory (LBL), Stanford University (Stanford), Idaho National Engineering Laboratory (INEL) and Parsons Environmental Engineering (Parsons). LBL and Stanford bring extensive experience in research in fractured rock systems. INEL and Parsons bring significant experience with the contamination problem at INEL
Rock fracture dynamics research at AECL's Underground Research Laboratory: applications to geological disposal of radioactive waste

Energy Technology Data Exchange (ETDEWEB)

Young, R.P. [Univ. of Toronto, Toronto, ON (Canada); Haycox, J.R. [Applied Seismology Consultants Limited, Shrewsbury, Shropshire (United Kingdom); Martino, J. [Atomic Energy of Canada Limited, Pinawa, MB (Canada)

2011-07-01

Studies of rock fracture dynamics at AECL's Underground Research Laboratory (URL) have helped to provide a fundamental understanding of how crystalline rock responds to stresses induced from excavation, pressurization and temperature changes. The data acquired continue to provide insights into how a facility for the future geological disposal of radioactive waste could be engineered. Research into microseismic (MS), acoustic emission (AE), and ultrasonic velocity measurements has been performed on the full-scale sealed, pressurized, and heated horizontal elliptical tunnel at the Tunnel Sealing Experiment (TSX). The continuous monitoring of the experiment for 8 years provides a unique dataset for the understanding of the medium-term performance of an engineered disposal facility. This paper summarizes the results, interpretations and key findings of the experiment paying particular focus to the heating and cooling/depressurization of the chamber. Initial drilling of the tunnel and bulkheads causes microfracturing around the tunnel, mapped by MS and AEs, and is used as a benchmark for fracturing representing the excavated damaged zone (EDZ). There is no further extension to the volume during pressurization or heating of the tunnel suggesting an increase in crack density and coalescence of cracks rather than extension into unfractured rock. The dominant structure within the seismic cloud has been investigated using a statistical approach applying the three-point method. MS events in the roof exhibit a dominant pattern of sub-horizontal and shallow-dipping well defined planar features, but during cooling and depressurization a 45 degree dip normal to the tunnel axis is observed, which may be caused by movement in the rock-concrete interface due to differential cooling of the bulkhead and host rock. Cooling and depressurization of the TSX have not led to a significant increase in the number of MS or AE events. Ultrasonic results suggest the rock gets even stiffer
Statistical analysis of the geological-hydrological conditions within part of the Eye-Dashwa pluton, Atikokan, northwestern Ontario

International Nuclear Information System (INIS)

Brown, P.A.; Rey, N.A.C.

1989-01-01

The occurrence and distribution of fracture-filling material within the Eye-Dashwa granite indicate that the dominant fracture system formed shortly after emplacement and cooling of the pluton at 2678 ± 67 Ma. Subsequent reactivation of these ancient fractures was accompanied by sequentially younger and lower temperature filling materials. These reopened ancient fractures are best developed in the upper 300-400 m of the rock mass and are commonly conduits for present-day groundwater flow. Multiple linear regression analysis performed on the geological variables identified a highly significant correlation between a number of these variable and hydraulic conductivity values measured in 25 m test sections of the boreholes. The predictive capability of the regression design was tested with seven new test data and found to be a valid estimator of the hydrogeological conditions

Fracturing across the multi-scales of diverse materials

Science.gov (United States)

Armstrong, R. W.; Antolovich, S. D.; Griffiths, J. R.; Knott, J. F.

2015-01-01

Everyone has to deal with fracturing of materials at one level or another, beginning from normal household chores and extending to the largest scale of observations reported for catastrophic events occurring on a geological level or even expanded to events in outer space. Such wide perspective is introduced in the current introduction of this theme issue. The follow-on organization of technical articles provides a flavour of the range in size scales at which fracturing occurs in a wide diversity of materials—from ‘fracking’ oil extraction and earth moving to laboratory testing of rock material and extending to the cracking of tooth enamel. Of important scientific interest are observations made and analysed at the smallest dimensions corresponding to the mechanisms by which fracture is either enhanced or hindered by permanent deformation or other processes. Such events are irrevocably linked to the atomic structure in all engineering materials, a sampling of which is presented, including results for crystalline and amorphous materials. Hooray for the broad subject description that is hoped to be appealing to the interested reader. PMID:25713460
Polyaxial stress-dependent permeability of a three-dimensional fractured rock layer

Science.gov (United States)

Lei, Qinghua; Wang, Xiaoguang; Xiang, Jiansheng; Latham, John-Paul

2017-12-01

A study about the influence of polyaxial (true-triaxial) stresses on the permeability of a three-dimensional (3D) fractured rock layer is presented. The 3D fracture system is constructed by extruding a two-dimensional (2D) outcrop pattern of a limestone bed that exhibits a ladder structure consisting of a "through-going" joint set abutted by later-stage short fractures. Geomechanical behaviour of the 3D fractured rock in response to in-situ stresses is modelled by the finite-discrete element method, which can capture the deformation of matrix blocks, variation of stress fields, reactivation of pre-existing rough fractures and propagation of new cracks. A series of numerical simulations is designed to load the fractured rock using various polyaxial in-situ stresses and the stress-dependent flow properties are further calculated. The fractured layer tends to exhibit stronger flow localisation and higher equivalent permeability as the far-field stress ratio is increased and the stress field is rotated such that fractures are preferentially oriented for shearing. The shear dilation of pre-existing fractures has dominant effects on flow localisation in the system, while the propagation of new fractures has minor impacts. The role of the overburden stress suggests that the conventional 2D analysis that neglects the effect of the out-of-plane stress (perpendicular to the bedding interface) may provide indicative approximations but not fully capture the polyaxial stress-dependent fracture network behaviour. The results of this study have important implications for understanding the heterogeneous flow of geological fluids (e.g. groundwater, petroleum) in subsurface and upscaling permeability for large-scale assessments.
Numerical modelling of single-phase flow in rough fractures with contacts

Science.gov (United States)

Olkiewicz, Piotr; Dabrowski, Marcin

2017-04-01

Fracture flow may dominate in rocks with low porosity and it can accompany both industrial and natural processes. Typical examples of such processes are natural flows in crystalline rocks and industrial flows in oil and gas production systems or hydraulic fracturing. Fracture flow provides an important mechanism for transporting mass and energy. The distribution of the apertures of fracture and contact area are the key parameters with regard to the fracture transmissivity. We use the method of correlated random fields [Mourzenko, 1996] to generate synthetic fracture geometry in 3D. The flow of an incompressible Newtonian viscous fluid in geological formation can be approximated by the Stokes, the Stokes-Brinkman or the Reynolds models. We use our own implementation of the finite element method based on MILAMIN [Dabrowski, 2008] to solve governing partial differential equation over domain. We compare the Stokes, the Stokes-Brinkamn and the Reynolds models for fracture flow based on systematic numerical simulations for a wide range of geometric parameters. Mismatch between the Reynolds and the Stokes models becomes significant with increasing fracture roughness or contact area. The Stokes-Brinkman model is more accurate than Reynolds models due to additional Laplacian term, which allows to fulfil no-slip boundary condition. We present condition when the Reynolds and the Stokes-Brinkman models are valid. In the last three decades many authors used the Reynolds equation for studying fracture flow because of its simplicity. We recommend using the Stokes-Brinkman model for fracture flow, which allows to fulfil no-slip boundary condition on asperities boundary and is more accurate for rough fractures than the Reynolds model.
Geology of the Tono area with focus on the Toki granite

International Nuclear Information System (INIS)

Lanaro, Flavio

2008-01-01

This chapter offers an overview of the petrography, fracturing and large-scale structures occurring in Toki granite at the Tono area (Gifu Pref., Japan). Geological descriptions of the investigated Shobasama and MIU Underground Laboratory Construction Site are also given together with the layout of the facility. The overview provides the starting point for the analyses related to the strength of the Toki granite treated in the rest of this report. (author)
The moderately fractured rock experiment: Background and overview

International Nuclear Information System (INIS)

Jensen, M.R.

2001-01-01

The Moderately Fractured Rock (MFR) experiment is conducted at Atomic Energy of Canada Limited's Underground Research Laboratory (URL) as part of Ontario Power Generation's Deep Geologic Repository Technology Program. The MFR experiment was initiated in the mid-1990s with the purpose of advancing the understanding of mass transport in MFR (fractures 1-5/m, k ≅ 10 -15 m 2 ) in which groundwater flow and solute migration occurs through a network of interconnected fractures. The experimental program has involved a series of multi-well forced gradient tracer tests at scales of 10-50 m within a ≅ 100,000 m 3 volume of MFR accessed from the 240 m level of the URL. The tracer tests conducted with non-reactive, reactive and colloidal tracers have served to explore the applicability of continuum models for prediction of groundwater flow and mass transport. Recently, a Modeling Task Force was created to re-examine tracer test experimental methodologies, MFR flow and transport conceptual models and provide a broader forum in which to apply alternative dual-permeability, discrete fracture and hybrid mathematical codes for flow system analysis. This paper provides a description of the MFR experiment, preliminary research findings and plans for the future
Comparison of 3-D geological and geophysical investigation methods in boreholes KI-KR1 at Aeaenekoski Kivetty site and RO-KR3 at Kuhmo Romuvaara site

International Nuclear Information System (INIS)

Labbas, K.

1997-01-01

The study is a part of the radioactive waste disposal investigations in Finland with the aim to compare three-dimensional geological and geophysical methods providing information on geologic fractures. Compared and described are the methods: core analysis, borehole television, dipmeter, borehole televiewer and differential flow measurements. (35 refs.)
Electromagnetic characterization of fractured rock for geological disposal studies of spent nuclear fuel

Energy Technology Data Exchange (ETDEWEB)

Eloranta, E. [Radiation and Nuclear Safety Authority, Helsinki (Finland); Ermutlu, M. [Nokia Research Center, Helsinki (Finland); Flykt, M.; Lindell, I.; Nikoskinen, K.; Sihvola, A. [Helsinki Univ. of Technology, Espoo (Finland). Electromagnetics Lab.

1998-04-01

In the report, the results of a joint research project carried out in 1991-1997 by the Finnish Radiation and Nuclear Safety Authority (STUK) and the Electromagnetics Laboratory of the Helsinki University of Technology are presented. The main purpose was to create computational models for electric potential responses when the medium is anisotropic and is bounded by a perfect magnetic conductor, a perfect electric conductor, and an anisotropic impedance surface. Furthermore, the geometry of two anisotropic half spaces and a layered medium were considered. The solutions of the problems were made using image theory. For modeling the electric potential in anisotropic medium with inhomogeneities, an integral equation was formulated. Also a wedge structure was treated as an extension to the traditional two parallel plate model of fracture geometry. The equivalentization of fracturing with anisotropy is a research area that still continues that still continues 46 refs. The publication contains also fourteen previous publications by authors
Geological history and its impact on the rock mechanics properties of the Olkiluoto site

International Nuclear Information System (INIS)

Hudson, J.A.; Cosgrove, J.W.

2006-03-01

This report is one of three documents with background information for supporting the development of Posiva's future rock mechanics programme. The other two reports are a summary of all the rock mechanics work completed for Posiva before 2005 (Posiva Working Report) and a technical audit of the numerical modeling work that has been conducted previously for Posiva (REC Memo). The purpose of this report is to establish the extent to which the mechanical properties of the rocks at the Olkiluoto site can be estimated from a knowledge of the geological environment. The main information required for rock mechanics studies of the site is a knowledge of the prevailing stress state, the properties of the intact rock, and the properties of the fractures at all scales - from sizes that could form blocks in the tunnel roof up to the major brittle deformation zones that could be influence the location of the ONKALO and the subsequent repository. Thus, the summary of the geological history in Chapter 2 concentrates on these features and we summarise the ductile and brittle deformational tectonic history of the site, with emphasis on the inferred stress states causing the deformations. Then, in Chapter 3, the rock stress, the hierarchy of brittle fracturing, the fracture properties and the mechanical properties of the rock mass are considered in the light of the geological environment. These features provide the baseline knowledge of the host rock from which the logic of the future rock mechanics programme can be developed, based on: the bedrock model; the site investigation results; the requirements for generating the site descriptive model; the prediction-outcome ONKALO studies; and numerically modeling the effects of excavation for design and safety analysis. The implications of this study for the future rock mechanics work are outlined in Chapter 4 with emphasis on the key features for modeling. (orig.)
10 CFR Appendix A to Part 100 - Seismic and Geologic Siting Criteria for Nuclear Power Plants

Science.gov (United States)

2010-01-01

... materials has occurred parallel to the fracture plane. It is distinct from other types of ground disruptions... history; (2) Identification and evaluation of tectonic structures underlying the site and the region... in order to permit appropriate consideration of the geologic history of such faults in establishing...
Evidence of Hierarchy in the Complex Fractured System of Geropotamos (Crete, Greece), as Extracted from Transient Electromagnetic Responses

Science.gov (United States)

Vallianatos, Filippos; Kouli, Maria; Kalisperi, Despina

2018-03-01

The essential goals of this paper are to test the transient electromagnetic (TEM) response in a fractured geological complex medium and to better understand the physics introduced by associating a roughness parameter β to the geological formation. An anomalous fractional diffusion approach is incorporated to describe the electromagnetic induction in rough multi-scaled geological structures. The multi-scaling characteristics of Geropotamos basin in Crete are revealed through the analysis of transient step-off response of an EM loop antenna. The semi-empirical parameters derived from late-time TEM measurements are correlated with the multi-scale heterogeneities of the medium. Certain interesting properties of the late-time slope γ(β) and the power law of near surface resistivity distribution, as extracted from TEM inversion for different depth, are presented. The analysis of the parameter γ(β) which scales the induced voltage in the loop in the late stage of the electromagnetic response leads to a different view of the EM geophysical data interpretation. We show that it is strongly correlated with areas of high fracture density within the geological formations of the Geropotamos area. For that reason, it is proposed as a local multi-scaling empirical index. The results of this paper suggest that anomalous diffusion could be a viable physical mechanism for the fractal transport of charge carriers, explaining observed late-time TEM responses across a variety of natural geological settings.
Poromechanical response of naturally fractured sorbing media

Science.gov (United States)

Kumar, Hemant

The injection of CO2 in coal seams has been utilized for enhanced gas recovery and potential CO2 sequestration in unmineable coal seams. It is advantageous because as it enhances the production and significant volumes of CO2 may be stored simultaneously. The key issues for enhanced gas recovery and geologic sequestration of CO2 include (1) Injectivity prediction: The chemical and physical processes initiated by the injection of CO2 in the coal seam leads to permeability/porosity changes (2) Up scaling: Development of full scale coupled reservoir model which may predict the enhanced production, associated permeability changes and quantity of sequestered CO2. (3) Reservoir Stimulation: The coalbeds are often fractured and proppants are placed into the fractures to prevent the permeability reduction but the permeability evolution in such cases is poorly understood. These issues are largely governed by dynamic coupling of adsorption, fluid exchange, transport, water content, stress regime, fracture geometry and physiomechanical changes in coals which are triggered by CO 2 injection. The understanding of complex interactions in coal has been investigated through laboratory experiments and full reservoir scale models are developed to answer key issues. (Abstract shortened by ProQuest.).
Legal aspects of the hydraulic fracturing method

Directory of Open Access Journals (Sweden)

Marta Duraj

2011-12-01

Full Text Available In recent months the possibility of extracting shale gas by way of the hydraulic fracturing method in Poland as well as across EU territory has been widely discussed. The European Parliament is to decide whether to ban this method. There are various legal, ecological and economical aspects influencing European legislators. It is hard not to notice how strongly the anti- and pro- hydraulic fracturing lobbies are connected with business. At the moment there are no specific regulations that relate directly to this extraction method, neither in the EU as a whole nor in Poland. However, in Poland a new Geological and Mining Act is supposed to come into force on 1st January 2012, which will regulate natural gas extraction with a view to ensure proper extraction of shale gas in the near future. This article is aimed at showing Polish regulations, both planned and currently in force, as well as the relevant EU law in respect of shale gas extraction. The author would like to emphasize the need to create one coherent legislative regime which would enable entrepreneurs to commence extraction by way of hydraulic fracturing without creating a danger for the environment.
Regional economic impacts of the unconventional promotion of natural gas (Hydraulic Fracturing). Preliminary study; Regionaloekonomische Auswirkungen der unkonventionellen Erdgasfoerderung (Hydraulic Fracturing). Vorstudie

Energy Technology Data Exchange (ETDEWEB)

Bizer, Kilian; Bossmeyer, Christoph

2012-07-01

Actually, there is a controversial public discussion on the exploitation of conventional natural gas by means of hydraulic fracturing (Fracking). The contribution under consideration examines the geologic, toxicological or technical as well as legal points of contact with respect to the different effects for the actor groups. Based on the existing scientific realizations, the regional economic effects of the fracking technology and the subsequent promotion of unconventional natural gas deposits have to be worked out.
Hypogeal geological survey in the "Grotta del Re Tiberio" natural cave (Apennines, Italy): a valid tool for reconstructing the structural setting

Science.gov (United States)

Ghiselli, Alice; Merazzi, Marzio; Strini, Andrea; Margutti, Roberto; Mercuriali, Michele

2011-06-01

As karst systems are natural windows to the underground, speleology, combined with geological surveys, can be useful tools for helping understand the geological evolution of karst areas. In order to enhance the reconstruction of the structural setting in a gypsum karst area (Vena del Gesso, Romagna Apennines), a detailed analysis has been carried out on hypogeal data. Structural features (faults, fractures, tectonic foliations, bedding) have been mapped in the "Grotta del Re Tiberio" cave, in the nearby gypsum quarry tunnels and open pit benches. Five fracture systems and six fault systems have been identified. The fault systems have been further analyzed through stereographic projections and geometric-kinematic evaluations in order to reconstruct the relative chronology of these structures. This analysis led to the detection of two deformation phases. The results permitted linking of the hypogeal data with the surface data both at a local and regional scale. At the local scale, fracture data collected in the underground have been compared with previous authors' surface data coming from the quarry area. The two data sets show a very good correspondence, as every underground fracture system matches with one of the surface fracture system. Moreover, in the cave, a larger number of fractures belonging to each system could be mapped. At the regional scale, the two deformation phases detected can be integrated in the structural setting of the study area, thereby enhancing the tectonic interpretation of the area ( e.g., structures belonging to a new deformation phase, not reported before, have been identified underground). The structural detailed hypogeal survey has, thus, provided very useful data, both by integrating the existing information and revealing new data not detected at the surface. In particular, some small structures ( e.g., displacement markers and short fractures) are better preserved in the hypogeal environment than on the surface where the outcropping
Prediction of geological and mechanical processes while disposing of high-level waste (HLW) into the earth crust

International Nuclear Information System (INIS)

Kedrovsky, O.L.; Morozov, V.N.

1992-01-01

Prediction of geological and mechanical processes while disposing of high-level waste of atomic industry into the earth crust is the fundamental base for ecological risk assessment (possible consequences) while developing repository designs. The subject of this paper is the analytical estimate of possibilities of rock fracturing mechanisms to predict isolation properties loss by massif beginning from crystal lattice of minerals up to large fracture disturbances under conditions of long-term influence of pressure, temperature, and radiation. To solve the problem possibilities of kinetic
Toughness-Dominated Regime of Hydraulic Fracturing in Cohesionless Materials

Science.gov (United States)

Germanovich, L. N.; Hurt, R. S.; Ayoub, J.; Norman, W. D.

2011-12-01

This work examines the mechanisms of hydraulic fracturing in cohesionless particulate materials with geotechnical, geological, and petroleum applications. For this purpose, experimental techniques have been developed, and used to quantify the initiation and propagation of hydraulic fractures in saturated particulate materials. The fracturing liquid is injected into particulate materials, which are practically cohesionless. The liquid flow is localized in thin self-propagating crack-like conduits. By analogy we call them 'cracks' or 'hydraulic fractures.' When a fracture propagates in a solid, new surfaces are created by breaking material bonds. Consequently, the material is in tension at the fracture tip. Because the particulate material is already 'fractured,' no new surface is created and no fracturing process per se is involved. Therefore, the conventional fracture mechanics principles cannot be directly applied. Based on the laboratory observations, performed on three particulate materials (Georgia Red Clay, silica flour, and fine sand, and their mixtures), this work offers physical concepts to explain the observed phenomena. The goal is to determine the controlling parameters of fracture behavior and to quantify their effects. An important conclusion of our work is that all parts of the cohesionless particulate material (including the tip zone of hydraulic fracture) are likely to be in compression. The compressive stress state is an important characteristic of hydraulic fracturing in particulate materials with low, or no, cohesion (such as were used in our experiments). At present, two kinematic mechanisms of fracture propagation, consistent with the compressive stress regime, can be offered. The first mechanism is based on shear bands propagating ahead of the tip of an open fracture. The second is based on the tensile strain ahead of the fracture tip and reduction of the effective stresses to zero within the leak-off zone. Scaling indicates that in our
Geologic and preliminary reservoir data on the Los Humeros Geothermal System, Puebla, Mexico

Energy Technology Data Exchange (ETDEWEB)

Ferriz, H.

1982-01-01

Exploratory drilling has confirmed the existence of a geothermal system in the Los Humeros volcanic center, located 180 km east of Mexico City. Volcanic activity in the area began with the eruption of andesites, followed by two major caldera-forming pyroclastic eruptions. The younger Los Potreros caldera is nested inside the older Los Humeros caldera. At later stages, basaltic andesite, dacite, and olivine basalt lavas erupted along the ring-fracture zones of both calderas. Geologic interpretation of structural, geophysical, and drilling data suggests that: (1) the water-dominated geothermal reservoir is hosted by the earliest andesitic volcanic pile, is bounded by the ring-fracture zone of the Los Potreros caldera, and is capped by the products of the oldest caldera-forming eruption; (2) permeability within the andesitic pile is provided by faults and fractures related to intracaldera uplift; (3) the geothermal system has potential for a large influx of meteoric water through portions of the ring-fracture zones of both calderas; and (4) volcanic centers with similar magmatic and structural conditions can be found in the eastern Cascades, USA.
Geophysical characterization of the role of fault and fracture systems for recharging groundwater aquifers from surface water of Lake Nasser

Directory of Open Access Journals (Sweden)

Khamis Mansour

2018-06-01

Full Text Available The role of the fracture system is important for enhancing the recharge or discharge of fluids in the subsurface reservoir. The Lake Nasser is consider one of the largest artificial lakes all over the world and contains huge bulk of storage water. In this study, the influence of fracture zones on subsurface fluid flow in groundwater reservoirs is investigated using geophysical techniques including seismicity, geoelectric and gravity data. These data have been utilized for exploring structural structure in south west Lake Nasser, and subsurface discontinuities (joints or faults notwithstanding its related fracture systems. Seismicity investigation gave us the comprehension of the dynamic geological structure sets and proposing the main recharging paths for the Nubian aquifer from Lake Nasser surface water. Processing and modelling of aerogravity data show that the greater thickness of sedimentary cover (700 m is located eastward and northward while basement outcrops occur at Umm Shaghir and Al Asr areas. Sixty-nine vertical electrical soundings (VES’s were used to delineate the subsurface geoelectric layers along eight profiles that help to realize the subsurface geological structure behind the hydrogeological conditions of the studied area. Keywords: Fracture system, Seismicity, Groundwater reservoir, Gravity, VES
2005 dossier: clay. Tome: phenomenological evolution of the geologic disposal

International Nuclear Information System (INIS)

2005-01-01

This document makes a status of the researches carried out by the French national agency of radioactive wastes (ANDRA) about the phenomenological processes taking place in an argilite-type geologic disposal facility for high-level and long-lived (HLLL) radioactive wastes. Content: 1 - introduction: goal, input data, time and space scales, long-time forecasting of the phenomenological evolution; 2 - the Meuse/Haute-Marne site, the HLLL wastes and the disposal concepts: impact of the repository architecture; 3 - initial state of the geologic environment prior to the building up of the repository: general framework, geologic formations, tectonics and fractures, surface environment, geologic synthesis; 4 - phenomenological processes: storage-related processes, geodynamics-related processes, time scales of processes and of radionuclides migration, independence and evolution similarities of the repository and of the geologic environment; 5 - heat loads: heat transfers between containers and geologic formations, spatial organization of the thermal load, for C-type wastes and spent fuels, for B-type wastes, synthesis of the repository thermal load; 6 - flows and liquid solution and gas transfers: hydraulic behaviour of surrounding Jurassic formations (Tithonian, Kimmeridgian, Callovian, Oxfordian); 7 - chemical phenomena: chemical evolution of ventilated facilities (alveoles, galleries, boreholes), chemical evolution of B-type waste alveoles and of gallery and borehole sealing after closure, far field chemical evolution of Callovo-Oxfordian argilites and of other surrounding formations; 8 - mechanical evolution of the disposal and of the surrounding geologic environment: creation of an initial excavated damaged zone (EDZ), mechanical evolution of ventilated galleries, alveoles and sealing before and after closure, large-scale mechanical evolution; 9 - geodynamical evolution of the Callovo-Oxfordian and other surrounding formations and of the surface environment: internal
Carbon dioxide sequestration induced mineral precipitation healing of fractured reservoir seals

Science.gov (United States)

Welch, N.; Crawshaw, J.

2017-12-01

Initial experiments and the thermodynaic basis for carbon dioxide sequestration induced mineral precipitation healing of fractures through reservoir seals will be presented. The basis of this work is the potential exists for the dissolution of reservoir host rock formation carbonate minerals in the acidified injection front of CO2 during sequestration or EOR. This enriched brine and the bulk CO2 phase will then flow through the reservoir until contact with the reservoir seal. At this point any fractures present in the reservoir seal will be the preferential flow path for the bulk CO2 phase as well as the acidified brine front. These fractures would currently be filled with non-acidified brine saturated in seal formation brine. When the acidifeid brine from the host formation and the cap rock brine mix there is the potential for minerals to fall out of solution, and for these precipitated minerals to decrease or entirely cut off the fluid flow through the fractures present in a reservoir seal. Initial equilibrium simulations performed using the PHREEQC1 database drived from the PHREEQE2 database are used to show the favorable conditions under which this mineral precipitation can occurs. Bench scale fluid mixing experiments were then performed to determine the kinetics of the mineral precipitation process, and determine the progress of future experiemnts involving fluid flow within fractured anhydrite reservoir seal samples. 1Parkhurst, D.L., and Appelo, C.A.J., 2013, Description of input and examples for PHREEQC version 3—A computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations: U.S. Geological Survey Techniques and Methods, book 6, chap. A43, 497 p., available only at https://pubs.usgs.gov/tm/06/a43/. 2Parkhurst, David L., Donald C. Thorstenson, and L. Niel Plummer. PHREEQE: a computer program for geochemical calculations. No. 80-96. US Geological Survey, Water Resources Division,, 1980.

Seismic signatures of the Lodgepole fractured reservoir in Utah-Wyoming overthrust belt

Energy Technology Data Exchange (ETDEWEB)

Parra, J.; Collier, H.; Angstman, B.

1997-08-01

In low porosity, low permeability zones, natural fractures are the primary source of permeability which affect both production and injection of fluids. The open fractures do not contribute much to porosity, but they provide an increased drainage network to any porosity. An important approach to characterizing the fracture orientation and fracture permeability of reservoir formations is one based upon the effects of such conditions on the propagation of acoustic and seismic waves in the rock. We present the feasibility of using seismic measurement techniques to map the fracture zones between wells spaced 2400 ft at depths of about 1000 ft. For this purpose we constructed computer models (which include azimuthal anisotropy) using Lodgepole reservoir parameters to predict seismic signatures recorded at the borehole scale, crosswell scale, and 3 D seismic scale. We have integrated well logs with existing 2D surfaces seismic to produce petrophysical and geological cross sections to determine the reservoir parameters and geometry for the computer models. In particular, the model responses are used to evaluate if surface seismic and crosswell seismic measurements can capture the anisotropy due to vertical fractures. Preliminary results suggested that seismic waves transmitted between two wells will propagate in carbonate fracture reservoirs, and the signal can be received above the noise level at the distance of 2400 ft. In addition, the large velocities contrast between the main fracture zone and the underlying unfractured Boundary Ridge Member, suggested that borehole reflection imaging may be appropriate to map and fracture zone thickness variation and fracture distributions in the reservoir.
Geologic environmental study

Energy Technology Data Exchange (ETDEWEB)

Kim, Chun Soo; Bae, Dae Seok; Kim, Kyung Su; Park, Byung Yoon; Koh, Young Kown; Chun, Kwan Sik; Kim, Jhin Wung

2000-05-01

The geoscience research works are focused on the production of geologic basic data accompanying with the technical development of geology and hydrogeologic characterization. The lithology of the Korean peninsula consists of a complex structure of 29 rock types from Archean to Quaternary. The wide distribution of Mesozoic plutonic rock is an important consideration as a potential host rock allowing flexibility of siting. The recent tectonic activities are limited to localized particular area, which can be avoided by excluding in the early stage of siting. Three rock types such as plutonic rocks, crystalline gneisses and massive volcanic rocks were suggested as the preferred host rocks for the further study on HLW disposal system. This report contains grouping of regional faults, and on the distributional characteristics of faults and fractures(zones) in terms of lithological domain and tectonical provinces. The regional groundwater regime can be grouped into 3 regimes by tectonic setting and four groundwater regions based on an altitute. Groundwaters can be grouped by their chemistry and host rocks. The origin of groundwater was proposed by isotope ({sup 1}8O, {sup 2}H, {sup 1}3C, {sup 3}4S, {sup 8}7Sr, {sup 1}5N) studies and the residence time of groundwater was inferred from their tritium contents. Based on the geochemical and isotope characteristics, the geochemical evolutions of each types of groundwater were simulated using SOLVEQ/CHILLER and PHREEQC programs.
A numerical study of water percolation through an unsaturated variable aperture fracture under coupled thermomechanical effects

International Nuclear Information System (INIS)

Tsang, C.F.; Noorishad, J.; Hale, F.V.

1991-12-01

In calculation of ground water travel times associated with performance assessment of a nuclear waste repository, the role of fractures may turn out to be very important. There are two aspects related to fracture flow that have not been fully resolved. The first is the effect of coupled thermomechanical impact on fracture apertures due to the thermal output of the nuclear waste repository. The second is the effect of the variable aperture nature of the fractures. The present paper is an exploratory study of the impact of these two effects on water percolation through unsaturated fractures. The paper is divided into two main sections. the first section describes a calculation of the thermomechanical behavior of the geologic formation around a waste repository. In this exploratory study we assume two major fractures, one vertical and one horizontal through the repository center. Temperatures and thermally induced stress fields are calculated. The second part of the paper considers the unsaturated case and describes a study of water infiltration from the land surface through the vertical fracture to the repository
Study on the methodology for hydrogeological site descriptive modelling by discrete fracture networks

International Nuclear Information System (INIS)

Tanaka, Tatsuya; Ando, Kenichi; Hashimoto, Shuuji; Saegusa, Hiromitsu; Takeuchi, Shinji; Amano, Kenji

2007-01-01

This study aims to establish comprehensive techniques for site descriptive modelling considering the hydraulic heterogeneity due to the Water Conducting Features in fractured rocks. The WCFs was defined by the interpretation and integration of geological and hydrogeological data obtained from the deep borehole investigation campaign in the Mizunami URL project and Regional Hydrogeological Study. As a result of surface based investigation phase, the block-scale hydrogeological descriptive model was generated using hydraulic discrete fracture networks. Uncertainties and remaining issues associated with the assumption in interpreting the data and its modelling were addressed in a systematic way. (author)
Evaluation of geological structure and uranium mineralization model in West Lemajung Sector, Kalan Basin, West Kalimantan

International Nuclear Information System (INIS)

Ngadenin; Sularto, P.

2000-01-01

The fieldwork is based on the data of strike (S0) and schistosity (S1) of cores that could not penetrate the geological structure model and result of observation on some cores has shown that U mineralization veins are not always parallel to S1. The problems were encountered in core drill data to improve the estimation of U resources from indication category to measured category. The purpose of the evaluation is to establish the advisability of geological structure model and U mineralization model which was applied by this time. The research used remapping of geological structure with surface method in the scale of 1:1000. The result of remapping shows the difference of the dipping between new geological structure model and the old model. The dipping of the new model is to South East until vertical and the old model is to North West until vertical and to South East until vertical. Despite the difference between both of them, the substantive of folding system is identical so that the new and old models can be applied in drilling in West Lemajung sector. U mineralization model of remapping result consists of 3 types : type 1 U mineralization lens form with West-East direction and vertical dipping which is associated with tourmaline, type 2 U mineralization filling in the open fractures with West-East direction and 70 o to North dipping and parallel with S1, and type 3 U mineralization fill in opening fractures with N 110 o - 130 o E the direction and 60 o to North East until subvertical dipping while the old model is only one type. It is U mineralization filling in the open fractures with West-East the direction and 70 o to North the dipping and parallel with S1. Because of this significant difference, data collection of drill core must follow the new mineralization model. (author)
Numerical Modeling and Investigation of Fluid-Driven Fracture Propagation in Reservoirs Based on a Modified Fluid-Mechanically Coupled Model in Two-Dimensional Particle Flow Code

Directory of Open Access Journals (Sweden)

Jian Zhou

2016-09-01

Full Text Available Hydraulic fracturing is a useful tool for enhancing rock mass permeability for shale gas development, enhanced geothermal systems, and geological carbon sequestration by the high-pressure injection of a fracturing fluid into tight reservoir rocks. Although significant advances have been made in hydraulic fracturing theory, experiments, and numerical modeling, when it comes to the complexity of geological conditions knowledge is still limited. Mechanisms of fluid injection-induced fracture initiation and propagation should be better understood to take full advantage of hydraulic fracturing. This paper presents the development and application of discrete particle modeling based on two-dimensional particle flow code (PFC2D. Firstly, it is shown that the modeled value of the breakdown pressure for the hydraulic fracturing process is approximately equal to analytically calculated values under varied in situ stress conditions. Furthermore, a series of simulations for hydraulic fracturing in competent rock was performed to examine the influence of the in situ stress ratio, fluid injection rate, and fluid viscosity on the borehole pressure history, the geometry of hydraulic fractures, and the pore-pressure field, respectively. It was found that the hydraulic fractures in an isotropic medium always propagate parallel to the orientation of the maximum principal stress. When a high fluid injection rate is used, higher breakdown pressure is needed for fracture propagation and complex geometries of fractures can develop. When a low viscosity fluid is used, fluid can more easily penetrate from the borehole into the surrounding rock, which causes a reduction of the effective stress and leads to a lower breakdown pressure. Moreover, the geometry of the fractures is not particularly sensitive to the fluid viscosity in the approximate isotropic model.
A study on deep geological environment for the radwaste disposal - Estimation of roughness for the quantitative analysis of fracture transmissivity

Energy Technology Data Exchange (ETDEWEB)

Kim, Jung Yul; Kim, J. Y.; Kim, Y. S.; Hyun, H. J. [Korea Institute of Geology, Mining and Materials, Taejon (Korea)

2000-03-01

Estimation of fracture roughness-as one of the basic hydraulic fracture parameters - is very important in assessing ground water flow described by using discrete fracture network modeling. Former manual estimation of the roughness for each fracture surface of drill cores is above all a tedious, time-consuming work and will often cause some ambiguities of roughness interpretation partly due to the subjective judgements of observers, and partly due to the measuring procedure itself. However, recently, indebt to the highly reliable Televiewer data for the fracture discrimination, it has led to a guess to develop a relationship between the traditional roughness method based on a linear profiles and the method from the Televiewer image based on a ellipsoidal profile. Hence, the aim of this work is to develop an automatic evaluation algorithm for measuring the roughness from the Televiewer images. A highly reliable software named 'RAF' has been developed and realized to the extent that its utility merits. In the developing procedure, various problems - such as the examination of a new base line(ellipsoidal) for measuring the unevenness of fracture, the elimination of overlapping fracture signatures or noise, the wavelet estimation according to the type of fractures and the digitalization of roughness etc. - were considered. With these consideration in mind, the newly devised algorithm for the estimation of roughness curves showed a great potential not only for avoiding ambiguities of roughness interpretation but also for the judgement of roughness classification. 12 refs., 23 figs. (Author)
Geological remote sensing-evaluation of image data

Energy Technology Data Exchange (ETDEWEB)

Nagatani, H

1977-01-01

During the nationwide geothermal investigation program (Japan) begun in 1973, five districts were chosen for evaluation of the effectiveness and limitations of aerial thermography. Using thermal images of Ibusuki City and Yamakawa-cho, geothermal resource areas were detected and related fracture zones were established by combining the thermal imagery and geological maps. At Ibusuki City, it was determined that the heat source was the Ata caldera, and that a fracture system connecting it to Lake Ikeda provides a conduit for geothermal fluids. Image plotting of thermal anomalies in the Hachimantai geothermal field was found to be an effective method for monitoring variation in thermal activity. LANDSAT imagery was anlayzed and lineament systems were detected in the mountains of the Kanto district. Followup of LANDSAT data by mapping teams confirmed a fault which intersects the major Kamitsuna fault in that district. This successful use of remote sensing data is encouraging but it is possible to draw only limited conclusions from it at present. Further refinement of analytical techniques is required.
Radionuclide Transport in Fractured Rock: Numerical Assessment for High Level Waste Repository

Directory of Open Access Journals (Sweden)

Claudia Siqueira da Silveira

2013-01-01

Full Text Available Deep and stable geological formations with low permeability have been considered for high level waste definitive repository. A common problem is the modeling of radionuclide migration in a fractured medium. Initially, we considered a system consisting of a rock matrix with a single planar fracture in water saturated porous rock. Transport in the fracture is assumed to obey an advection-diffusion equation, while molecular diffusion is considered the dominant mechanism of transport in porous matrix. The partial differential equations describing the movement of radionuclides were discretized by finite difference methods, namely, fully explicit, fully implicit, and Crank-Nicolson schemes. The convective term was discretized by the following numerical schemes: backward differences, centered differences, and forward differences. The model was validated using an analytical solution found in the literature. Finally, we carried out a simulation with relevant spent fuel nuclide data with a system consisting of a horizontal fracture and a vertical fracture for assessing the performance of a hypothetical repository inserted into the host rock. We have analysed the bentonite expanded performance at the beginning of fracture, the quantified radionuclide released from a borehole, and an estimated effective dose to an adult, obtained from ingestion of well water during one year.
Hydrological and thermal issues concerning a nuclear waste repository in fractured rocks

International Nuclear Information System (INIS)

Wang, J.S.Y.

1991-12-01

The characterization of the ambient conditions of a potential site and the assessment of the perturbations induced by a nuclear waste repository require hydrological and thermal investigations of the geological formations at different spatial and temporal scales. For high-level wastes, the near-field impacts depend on the heat power of waste packages and the far-field long-term perturbations depend on the cumulative heat released by the emplaced wastes. Surface interim storage of wastes for several decades could lower the near-field impacts but would have relatively small long-term effects if spent fuels were the waste forms for the repository. One major uncertainty in the assessment of repository impacts is from the variation of hydrological properties in heterogeneous media, including the effects of fractures as high-permeability flow paths for containment migration. Under stress, a natural fracture cannot be represented by the parallel plate model. The rock surface roughness, the contact area, and the saturation state in the rock matrix could significantly change the fracture flow. In recent years, the concern of fast flow through fractures in saturated media has extended to the unsaturated zones. The interactions at different scales between fractures and matrix, between fractured matrix unites and porous units, and between formations and faults are discussed
Testing Novel CR-39 Detector Deployment System For Identification of Subsurface Fractures, Soda Springs, ID

Energy Technology Data Exchange (ETDEWEB)

McLing, Travis [Idaho National Lab. (INL), Idaho Falls, ID (United States); Carpenter, Michael [Idaho National Lab. (INL), Idaho Falls, ID (United States); Brandon, William [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zavala, Bernie [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2015-06-01

The Environmental Protection Agency (EPA) has teamed with Battelle Energy Alliance, LLC (BEA) at Idaho National Laboratory (INL) to facilitate further testing of geologic-fracture-identification methodology at a field site near the Monsanto Superfund Site located in Soda Springs, Idaho. INL has the necessary testing and technological expertise to perform this work. Battelle Memorial Institute (BMI) has engaged INL to perform this work through a Work for Others (WFO) Agreement. This study continues a multi-year collaborative effort between INL and EPA to test the efficacy of using field deployed Cr-39 radon in soil portals. This research enables identification of active fractures capable of transporting contaminants at sites where fractures are suspected pathways into the subsurface. Current state of the art methods for mapping fracture networks are exceedingly expensive and notoriously inaccurate. The proposed WFO will evaluate the applicability of using cheap, readily available, passive radon detectors to identify conductive geologic structures (i.e. fractures, and fracture networks) in the subsurface that control the transport of contaminants at fracture-dominated sites. The proposed WFO utilizes proven off-the-shelf technology in the form of CR-39 radon detectors, which have been widely deployed to detect radon levels in homes and businesses. In an existing collaborative EPA/INL study outside of this workscope,. CR-39 detectors are being utilized to determine the location of active transport fractures in a fractured granitic upland adjacent to a landfill site at the Fort Devens, MA that EPA-designated as National Priorities List (NPL) site. The innovative concept of using an easily deployed port that allows the CR-39 to measure the Rn-222 in the soil or alluvium above the fractured rock, while restricting atmospheric Rn-222 and soil sourced Ra from contaminating the detector is unique to INL and EPA approach previously developed. By deploying a series of these
Characterization of Fractured Reservoirs Using a Combination of Downhole Pressure and Self-Potential Transient Data

Directory of Open Access Journals (Sweden)

Yuji Nishi

2012-01-01

Full Text Available In order to appraise the utility of self-potential (SP measurements to characterize fractured reservoirs, we carried out continuous SP monitoring using multi Ag-AgCl electrodes installed within two open holes at the Kamaishi Mine, Japan. The observed ratio of SP change to pressure change associated with fluid flow showed different behaviors between intact host rock and fractured rock regions. Characteristic behavior peculiar to fractured reservoirs, which is predicted from numerical simulations of electrokinetic phenomena in MINC (multiple interacting continua double-porosity media, was observed near the fractures. Semilog plots of the ratio of SP change to pressure change observed in one of the two wells show obvious transition from intermediate time increasing to late time stable trends, which indicate that the time required for pressure equilibration between the fracture and matrix regions is about 800 seconds. Fracture spacing was estimated to be a few meters assuming several micro-darcies (10-18 m2 of the matrix region permeability, which is consistent with geological and hydrological observations.
Characterization of the fracturation of rock masses for determining flow

International Nuclear Information System (INIS)

Derlich, S.

1984-02-01

Flow in a rock mass is the consequence of the permeability of the rock, which can be roughly separated into matrix permeability and fissure permeability. In crystalline rocks fissure permeability is dominant, especially where the rocks are extensively fractured. It is thus essential, by means of studies either at the surface or underground, to characterize the volume fracturation in the mass considered. The purpose of this paper is to illustrate the methodology for analysing fracturation at a site by the studies performed on the granite mass of Auriat in the French Massif Central. A number of geology laboratories have participated in this study and a broad spectrum of observations has been made which can be used for determining the various stages of a study with a view to selection of a site, the advantages and limitations of each method or study plan and additional methods which need to be used for gaining as complete a picture as possible of the fracturation. A brief examination of the results obtained at Auriat enables the relative advantages of using these various methods at a particular site to be compared
FracPaQ: a MATLAB™ toolbox for the quantification of fracture patterns

Science.gov (United States)

Healy, David; Rizzo, Roberto; Farrell, Natalie; Watkins, Hannah; Cornwell, David; Gomez-Rivas, Enrique; Timms, Nick

2017-04-01

The patterns of fractures in deformed rocks are rarely uniform or random. Fracture orientations, sizes, shapes and spatial distributions often exhibit some kind of order. In detail, there may be relationships among the different fracture attributes e.g. small fractures dominated by one orientation, larger fractures by another. These relationships are important because the mechanical (e.g. strength, anisotropy) and transport (e.g. fluids, heat) properties of rock depend on these fracture patterns and fracture attributes. This presentation describes an open source toolbox to quantify fracture patterns, including distributions in fracture attributes and their spatial variation. Software has been developed to quantify fracture patterns from 2-D digital images, such as thin section micrographs, geological maps, outcrop or aerial photographs or satellite images. The toolbox comprises a suite of MATLAB™ scripts based on published quantitative methods for the analysis of fracture attributes: orientations, lengths, intensity, density and connectivity. An estimate of permeability in 2-D is made using a parallel plate model. The software provides an objective and consistent methodology for quantifying fracture patterns and their variations in 2-D across a wide range of length scales. Our current focus for the application of the software is on quantifying crack and fracture patterns in and around fault zones. There is a large body of published work on the quantification of relatively simple joint patterns, but fault zones present a bigger, and arguably more important, challenge. The methods presented are inherently scale independent, and a key task will be to analyse and integrate quantitative fracture pattern data from micro- to macro-scales. New features in this release include multi-scale analyses based on a wavelet method to look for scale transitions, support for multi-colour traces in the input file processed as separate fracture sets, and combining fracture traces
Transport of synthetic colloids through single saturated fractures: A literature review

International Nuclear Information System (INIS)

Reimus, P.W.

1995-07-01

Colloids having the same surface charge sign as the bulk of the geologic media in a groundwater system may be able to travel through the system faster than soluble species because they will follow fluid streamlines more closely and they should have less tendency to diffuse into pores or dead spaces in the media than soluble species. Synthetic colloids with uniform, controlled properties may be ideal for serving as open-quotes worst-caseclose quotes tracers that provide lower-bound estimates of contaminant travel times in hydrologic systems. This report discusses a review of the literature pertaining to colloid transport in single saturated natural fractures. After a brief background discussion to put the literature review in perspective, the phenomenon of colloid transport in saturated fractures is divided into three major topics, each of which is reviewed in detail: (1) saturated fluid flow through fractures; (2) colloid transport by convection, diffusion, and force fields; and (3) colloid interactions with surfaces. It is suggested that these phenomena be accounted for in colloid transport models by using (1) lubrication theory to describe water flow through fractures, (2) particle tracking methods to describe colloid transport in fractures, and (3) a kinetic boundary layer approximation to describe colloid interactions with fracture walls. These methods offer better computational efficiency and better experimental accessibility to model parameters than rigorously solving the complete governing equations
Geology and ground water in north-central Santa Cruz County, California

Science.gov (United States)

Johnson, Michael J.

1980-01-01

North-central Santa Cruz County is underlain mainly by folded sedimentary rocks of Tertiary and Cretaceous age that have been highly fractured by movements in the San Andreas fault system. Ground water is stored in fractures within shale and mudstone formations and in intergranular pore spaces within fine- to very fine-grained sandstone and siltstone formations. Fewer than 10% of the wells yield more than 15 gallons of water per minute. The water in most wells is moderately hard to very hard, is generally of a sodium bicarbonate or calcium bicarbonate type, and commonly has excessive concentrations of iron or manganese. Of the many geologic units in the study area, only the Purisima Formation of Pliocene age has the potential to sustain well yields greater than 100 gallons per minute. (USGS)
Uncertainty in forecasting breakthrough of fluid transported through fractures

International Nuclear Information System (INIS)

Horne, R.N.

1989-01-01

Tracer experiments in geothermal reservoirs emphasize the very great variability in rates of fluid movement through fractured rocks. This variability extends from the 10-meter to the kilometer-length scale. Thus tracer returns have been observed at some locations within hours at distances of up to 1 kilometer from the injection point, while other much nearer locations in the same formation do not observe the tracer until much later. In addition, transport rates have sometimes been extremely fast (up to 100 m/hr) even over such distances. This paper discusses the conclusions reached after compiling the results of a large number of tracer tests in several different fractured reservoirs. It is evident in some cases that large-scale geological features, such as faults, are responsible for the variations in tracer return time. In other cases, there is no clear physical description that explains the differences. These results suggest that there will be no a priori way of forecasting transport rates in fractured systems without performing a tracer test
Characterising rock fracture aperture-spacing relationships using power-law relationships: some considerations

Science.gov (United States)

Brook, Martin; Hebblewhite, Bruce; Mitra, Rudrajit

2016-04-01

The size-scaling of rock fractures is a well-studied problem in geology, especially for permeability quantification. The intensity of fractures may control the economic exploitation of fractured reservoirs because fracture intensity describes the abundance of fractures potentially available for fluid flow. Moreover, in geotechnical engineering, fractures are important for parameterisation of stress models and excavation design. As fracture data is often collected from widely-spaced boreholes where core recovery is often incomplete, accurate interpretation and representation of fracture aperture-frequency relationships from sparse datasets is important. Fracture intensity is the number of fractures encountered per unit length along a sample scanline oriented perpendicular to the fractures in a set. Cumulative frequency of fractures (F) is commonly related to fracture aperture (A) in the form of a power-law (F = aA-b), with variations in the size of the a coefficient between sites interpreted to equate to fracture frequency for a given aperture (A). However, a common flaw in this approach is that even a small change in b can have a large effect on the response of the fracture frequency (F) parameter. We compare fracture data from the Late Permian Rangal Coal Measures from Australia's Bowen Basin, with fracture data from Jurassic carbonates from the Sierra Madre Oriental, northeastern Mexico. Both power-law coefficient a and exponent b control the fracture aperture-frequency relationship in conjunction with each other; that is, power-laws with relatively low a coefficients have relatively high b exponents and vice versa. Hence, any comparison of different power-laws must take both a and b into consideration. The corollary is that different sedimentary beds in the Sierra Madre carbonates do not show ˜8× the fracture frequency for a given fracture aperture, as based solely on the comparison of coefficient a. Rather, power-law "sensitivity factors" developed from both
ROCK-CAD - computer aided geological modelling system

International Nuclear Information System (INIS)

Saksa, P.

1995-12-01

The study discusses surface and solid modelling methods, their use and interfacing with geodata. Application software named ROCK-CAD suitable for geological bedrock modelling has been developed with support from Teollisuuden Voima Oy (TVO). It has been utilized in the Finnish site characterization programme for spent nuclear fuel waste disposal during the 1980s and 1990s. The system is based on the solid modelling technique. It comprises also rich functionality for the particular geological modelling scheme. The ROCK-CAD system provides, among other things, varying graphical vertical and horizontal intersections and perspective illustrations. The specially developed features are the application of the boundary representation modelling method, parametric object generation language and the discipline approach. The ROCK-CAD system has been utilized in modelling spatial distribution of rock types and fracturing structures in TVO's site characterization. The Olkiluoto site at Eurajoki serves as an example case. The study comprises the description of the modelling process, models and illustration examples. The utilization of bedrock models in site characterization, in tentative repository siting as well as in groundwater flow simulation is depicted. The application software has improved the assessment of the sites studied, given a new basis for the documentation of interpretation and modelling work, substituted hand-drawing and enabled digital transfer to numerical analysis. Finally, aspects of presentation graphics in geological modelling are considered. (84 refs., 30 figs., 11 tabs.)
Effect of Random Natural Fractures on Hydraulic Fracture Propagation Geometry in Fractured Carbonate Rocks

Science.gov (United States)

Liu, Zhiyuan; Wang, Shijie; Zhao, Haiyang; Wang, Lei; Li, Wei; Geng, Yudi; Tao, Shan; Zhang, Guangqing; Chen, Mian

2018-02-01

Natural fractures have a significant influence on the propagation geometry of hydraulic fractures in fractured reservoirs. True triaxial volumetric fracturing experiments, in which random natural fractures are created by placing cement blocks of different dimensions in a cuboid mold and filling the mold with additional cement to create the final test specimen, were used to study the factors that influence the hydraulic fracture propagation geometry. These factors include the presence of natural fractures around the wellbore, the dimension and volumetric density of random natural fractures and the horizontal differential stress. The results show that volumetric fractures preferentially formed when natural fractures occurred around the wellbore, the natural fractures are medium to long and have a volumetric density of 6-9%, and the stress difference is less than 11 MPa. The volumetric fracture geometries are mainly major multi-branch fractures with fracture networks or major multi-branch fractures (2-4 fractures). The angles between the major fractures and the maximum horizontal in situ stress are 30°-45°, and fracture networks are located at the intersections of major multi-branch fractures. Short natural fractures rarely led to the formation of fracture networks. Thus, the interaction between hydraulic fractures and short natural fractures has little engineering significance. The conclusions are important for field applications and for gaining a deeper understanding of the formation process of volumetric fractures.

Hydromechanical and Thermomechanical Behaviour of Elastic Fractures during Thermal Stimulation of Naturally Fractured Reservoirs

Science.gov (United States)

Jalali, Mohammadreza; Valley, Benoît

2015-04-01

During the last two decades, incentives were put in place in order to feed our societies in energy with reduced CO2 emissions. Various policies have been considered to fulfill this strategy such as replacing coal by natural gas in power plants, producing electricity using CO2 free resources, and CO2 sequestration as a remediation for large point-source emitters (e.g. oil sands facilities, coal-fired power plants, and cement kilns). Naturally fractured reservoirs (NFRs) are among those geological structures which play a crucial role in the mentioned energy revolution. The behavior of fractured reservoirs during production processes is completely different than conventional reservoirs because of the dominant effects of fractures on fluid flux, with attendant issues of fracture fabric complexity and lithological heterogeneity. The level of complexity increases when thermal effects are taking place - as during the thermal stimulation of these stress-sensitive reservoirs in order to enhance the gas production in tight shales and/or increase the local conductivity of the fractures during the development of enhanced geothermal systems - where temperature is introduced as another degree of freedom in addition to pressure and displacement (or effective stress). Study of these stress-pressure-temperature effects requires a thermo-hydro-mechanical (THM) coupling approach, which considers the simultaneous variation of effective stress, pore pressure, and temperature and their interactions. In this study, thermal, hydraulic and mechanical behavior of partially open and elastic fractures in a homogeneous, isotropic and low permeable porous rock is studied. In order to compare the hydromechanical (HM) and thermomechanical (TM) characteristics of these fractures, three different injection scenarios, i.e. constant isothermal fluid injection rate, constant cooling without any fluid injection and constant cold fluid injection, are considered. Both thermomechanical and hydromechanical
Study of geologic-structural situation around Semipalatinsk test site test - holes using space images automated decoding method

International Nuclear Information System (INIS)

Gorbunova, Eh.M.; Ivanchenko, G.N.

2004-01-01

Performance of underground nuclear explosions (UNE) leads to irreversible changes in geological environment around the boreholes. In natural environment it was detected inhomogeneity of rock massif condition changes, which depended on characteristics of the underground nuclear explosion, anisotropy of medium and presence of faulting. Application of automated selection and statistic analysis of unstretched lineaments in high resolution space images using special software pack LESSA allows specifying the geologic-structural features of Semipalatinsk Test Site (STS), ranging selected fracture zones, outlining and analyzing post-explosion zone surface deformations. (author)
Geology of the Lachesis Tessera Quadrangle (V-18), Venus

Science.gov (United States)

McGowan, Eileen M.; McGill, George G.

2010-01-01

The Lachesis Tessera Quadrangle (V-18) lies between 25deg and 50deg north, 300deg and 330deg east. Most of the quadrangle consists of "regional plains" (1) of Sedna and Guinevere Planitiae. A first draft of the geology has been completed, and the tentative number of mapped units by terrain type is: tesserae - 2; plains - 4; ridge belts - 1; fracture belts - 1 (plus embayed fragments of possible additional belts); coronae - 5; central volcanoes - 2; shield flows - 2; paterae - 1; impact craters - 13; undifferentiated flows - 1; bright materials - 1.
Importance of the study on recharge for the evaluation of potential impact of uranium mining on fractured aquifers. Case study: URA/INB (Caetite, Bahia, Brazil)

International Nuclear Information System (INIS)

Silva, Liliane Ferreira da; Matos, Evando Carele de

2007-01-01

The domain of the crystalline rocks, that predominant at the brazilian semiarid, presents fractured type aquifers systems, and their spatial distribution is done in very heterogeneous way, since the underground water depends upon the underground geological characteristics and the climate conditions. So, it is very important to study the geologic structure of the area, observing the depth and distribution of the fractures and failure, their relationship with the topography and with water wells productivity, and it is possible to obtain information explaining the fact that frequently producer and dry wells are placed near to each other, and where are positioned the fractures in the space and how they are connected to each other. Those data will be used in the near future to predict also the fluid mobility, through the use of transport numerical models. In the present study case, the fractured aquifer represents the main water source for the mine industrial complex and for the rural community near the enterprise as well. In this case, the study presents the description of the fractures obtained on tubular wells, relating with topography and physic-chemical parameters of the water. (author)
Hydraulic fracturing in shales: the spark that created an oil and gas boom

Science.gov (United States)

Olson, J. E.

2017-12-01

In the oil and gas business, one of the valued properties of a shale was its lack of flow capacity (its sealing integrity) and its propensity to provide mechanical barriers to hydraulic fracture height growth when exploiting oil and gas bearing sandstones. The other important property was the high organic content that made shale a potential source rock for oil and gas, commodities which migrated elsewhere to be produced. Technological advancements in horizontal drilling and hydraulic fracturing have turned this perspective on its head, making shale (or other ultra-low permeability rocks that are described with this catch-all term) the most prized reservoir rock in US onshore operations. Field and laboratory results have changed our view of how hydraulic fracturing works, suggesting heterogeneities like bedding planes and natural fractures can cause significant complexity in hydraulic fracture growth, resulting in induced networks of fractures whose details are controlled by factors including in situ stress contrasts, ductility contrasts in the stratigraphy, the orientation and strength of pre-existing natural fractures, injection fluid viscosity, perforation cluster spacing and effective mechanical layer thickness. The stress shadowing and stress relief concepts that structural geologists have long used to explain joint spacing and orthogonal fracture pattern development in stratified sequences are key to understanding optimal injection point spacing and promotion of more uniform length development in induced hydraulic fractures. Also, fracture interaction criterion to interpret abutting vs crossing natural fracture relationships in natural fracture systems are key to modeling hydraulic fracture propagation within natural fractured reservoirs such as shale. Scaled physical experiments provide constraints on models where the physics is uncertain. Numerous interesting technical questions remain to be answered, and the field is particularly appealing in that better
Evaluation of geophysical techniques for identifying fractures in program wells in Deaf Smith County, Texas: Revision 1, Topical report

International Nuclear Information System (INIS)

Gillespie, R.P.; Siminitz, P.C.

1987-08-01

Quantitative information about the presence and orientation of fractures is essential for the understanding of the geomechanical and geohydrological behavior of rocks. This report evaluates various borehole geophysical techniques for characterizing fractures in three Civilian Radioactive Waste Management (CRWM) Program test wells in the Palo Duro Basin in Deaf Smith County, Texas. Emphasis has been placed on the Schlumberger Fracture Identification Log (FIL) which detects vertical fractures and provides data for calculation of orientation. Depths of FIL anomalies were compared to available core. It was found that the application of FIL results to characterize fracture frequency or orientation is inappropriate at this time. The uncertainties associated with the FIL information render the information unreliable. No geophysical logging tool appears to unequivocally determine the location and orientation of fractures in a borehole. Geologic mapping of the exploratory shafts will ultimately provide the best data on fracture frequency and orientation at the proposed repository site. 22 refs., 6 figs., 3 tabs
Ultramafic-derived arsenic in a fractured bedrock aquifer

International Nuclear Information System (INIS)

Ryan, Peter C.; Kim, Jonathan; Wall, Andrew J.; Moen, Jonathan C.; Corenthal, Lilly G.; Chow, Daniel R.; Sullivan, Colleen M.; Bright, Kevin S.

2011-01-01

Highlights: → Arsenic is elevated in groundwater from a fractured bedrock aquifer system in northern Vermont, USA. → The arsenic source is serpentinized ultramafic rock. → Antigorite, magnetite (MgCO 3 ) and magnetite (Fe 3 O 4 ) appear to be the main mineralogical hosts of arsenic in the ultramafic rock. → Arsenic appears to be introduced to the ultramafic rock when As-bearing fluids are driven out of sediments during subduction. → The occurrence of serpentinized ultramafic rocks in many orogenic belts suggests that similar arsenic anomalies may occur in geologically-similar terranes globally. - Abstract: In the fractured bedrock aquifer of northern Vermont, USA, As concentrations in groundwater range from 3 ) with lesser amounts in magnetite (Fe 3 O 4 ). Hydrochemistry of monitoring wells drilled into fractured ultramafic rock in a groundwater recharge area with no anthropogenic As source reveals above background As (2-9 μg/L) and an Mg-HCO 3 hydrochemical signature that reflects dissolution of antigorite and magnesite, confirming that As in groundwater can be derived from ultramafic rock dissolution. Arsenic mobility in groundwater affected by ultramafic rock dissolution may be enhanced by alkaline pH values and relatively high HCO 3 - concentrations.
Oil recovery enhancement from fractured, low permeability reservoirs. [Carbonated Water

Energy Technology Data Exchange (ETDEWEB)

Poston, S.W.

1991-01-01

The results of the investigative efforts for this jointly funded DOE-State of Texas research project achieved during the 1990-1991 year may be summarized as follows: Geological Characterization - Detailed maps of the development and hierarchical nature the fracture system exhibited by Austin Chalk outcrops were prepared. The results of these efforts were directly applied to the development of production decline type curves applicable to a dual-fracture-matrix flow system. Analysis of production records obtained from Austin Chalk operators illustrated the utility of these type curves to determine relative fracture/matrix contributions and extent. Well-log response in Austin Chalk wells has been shown to be a reliable indicator of organic maturity. Shear-wave splitting concepts were used to estimate fracture orientations from Vertical Seismic Profile, VSP data. Several programs were written to facilitate analysis of the data. The results of these efforts indicated fractures could be detected with VSP seismic methods.Development of the EOR Imbibition Process - Laboratory displacement as well as Magnetic Resonance Imaging, MRI and Computed Tomography, CT imaging studies have shown the carbonated water-imbibition displacement process significantly accelerates and increases recovery from oil saturated, low permeability rocks.Field Tests - Two operators amenable to conducting a carbonated water flood test on an Austin Chalk well have been identified. Feasibility studies are presently underway.
Oil Recovery Enhancement from Fractured, Low Permeability Reservoirs. [Carbonated Water

Science.gov (United States)

Poston, S. W.

1991-01-01

The results of the investigative efforts for this jointly funded DOE-State of Texas research project achieved during the 1990-1991 year may be summarized as follows: Geological Characterization - Detailed maps of the development and hierarchical nature the fracture system exhibited by Austin Chalk outcrops were prepared. The results of these efforts were directly applied to the development of production decline type curves applicable to a dual-fracture-matrix flow system. Analysis of production records obtained from Austin Chalk operators illustrated the utility of these type curves to determine relative fracture/matrix contributions and extent. Well-log response in Austin Chalk wells has been shown to be a reliable indicator of organic maturity. Shear-wave splitting concepts were used to estimate fracture orientations from Vertical Seismic Profile, VSP data. Several programs were written to facilitate analysis of the data. The results of these efforts indicated fractures could be detected with VSP seismic methods. Development of the EOR Imbibition Process - Laboratory displacement as well as Magnetic Resonance Imaging, MRI and Computed Tomography, CT imaging studies have shown the carbonated water-imbibition displacement process significantly accelerates and increases recovery from oil saturated, low permeability rocks. Field Tests - Two operators amenable to conducting a carbonated water flood test on an Austin Chalk well have been identified. Feasibility studies are presently underway.
Focused modelling. Fracture identification in Olkiluoto borehole OL-KR04

International Nuclear Information System (INIS)

Jokinen, J.; Jakobsson, K.

2004-10-01

An extensive set of measured borehole data has been obtained from geological repository investigations in the bedrock of Olkiluoto. Our hypothesis is that geophysical data may be used more efficiently to identify and classify fracture zones. It is known that several geophysical logging methods yield useful information outside the borehole walls that cannot be reached otherwise. At present, this data is used for additional fracture characterization but not for identification purposes. The study focuses on the application of 14 different geophysical data measured in the borehole OL-KR04. The whole data set is divided into main groups using the Principal Component Analysis (PCA). Each group is composed mainly of sensitive methods detecting specific physical characteristics. The main groups from the geophysical point of view are open fractures, reduced density, increased electrical conductivity, and increased natural radiation. The Varimax optimization method is used to maximize the importance of supporting data as well as to emphasize differences between the discovered principal components. In fracture zone analysis, drilling core samples and the hydrological measurement results form an indispensable data set. For practical reasons, and in order to fulfill the requirements of the PCA analysis, S-wave velocity and electrical resistivity measurements are also performed. A combination of these methods, simultaneously applied using suitable 'trigger limits', identifies penetrated extensive fracture sections in a borehole cost-effectively and unambiguously. (orig.)
Geology of the Source Physics Experiment Site, Climax Stock, Nevada National Security Site

Energy Technology Data Exchange (ETDEWEB)

Townsend, M., Prothro, L. B., Obi, C.

2012-03-15

A test bed for a series of chemical explosives tests known as Source Physics Experiments (SPE) was constructed in granitic rock of the Climax stock, in northern Yucca Flat at the Nevada National Security Site in 2010-2011. These tests are sponsored by the U.S. Department of Energy, National Nuclear Security Administration's National Center for Nuclear Security. The test series is designed to study the generation and propagation of seismic waves, and will provide data that will improve the predictive capability of calculational models for detecting and characterizing underground explosions. Abundant geologic data are available for the area, primarily as a result of studies performed in conjunction with the three underground nuclear tests conducted in the Climax granite in the 1960s and a few later studies of various types. The SPE test bed was constructed at an elevation of approximately 1,524 meters (m), and consists of a 91.4-centimeter (cm) diameter source hole at its center, surrounded by two rings of three 20.3-cm diameter instrument holes. The inner ring of holes is positioned 10 m away from the source hole, and the outer ring of holes is positioned 20 m from the source hole. An initial 160-m deep core hole was drilled at the location of the source hole that provided information on the geology of the site and rock samples for later laboratory testing. A suite of geophysical logs was run in the core hole and all six instruments holes to obtain matrix and fracture properties. Detailed information on the character and density of fractures encountered was obtained from the borehole image logs run in the holes. A total of 2,488 fractures were identified in the seven boreholes, and these were ranked into six categories (0 through 5) on the basis of their degree of openness and continuity. The analysis presented here considered only the higher-ranked fractures (ranks 2 through 5), of which there were 1,215 (approximately 49 percent of all fractures identified
Preliminary geologic and geophysical data of the UE25a-3 exploratory drill hole, Nevada Test Site, Nevada

International Nuclear Information System (INIS)

Maldonado, F.; Muller, D.C.; Morrison, J.N.

1979-09-01

The UE25a-3 drill hole, located in the Calico Hills area, was drilled as part of an effort to evaluate the Calico Hills area as a possible nuclear waste repository site. The purpose of the drill hole was to verify the existence of an intrusive crystalline body in the subsurface and to determine the stratigraphy, structure, and nature of fractures of the cored rocks. Cored samples were obtained for mineral, chemical, and material property analyses. Numerous high-angle faults and brecciated zones were intersected by the drill hole. The units cored were intensely fractured with fracture analysis of the core consisting of frequency of fractures, dips of fractures, open and closed (sealed) fractures and types of fracture sealing or coating material. Twenty-four hundred and thirty fractures, representing approximately 30 percent of the fractures present, indicate an average fracture frequency of 13.2 fractures per meter, predominantly high-angle dips with 66 percent of the fractures closed. Fractures in the argillite interval are sealed or coated predominantly with kaolinite, nacrite, and dickite. Calcite, chlorite, and magnetite are present in fractures in the altered argillite interval. Fractures in the marble interval are sealed or coated with calcite, dolomite, and ferruginous clay. The core index indicates that the lower half of the drilled interval is more competent than the upper half. Borehole geophysical logs were run by the Birdwell Division of Seismograph Service Corporation for geologic correlations and lithologic characterizations. The logs include: caliper, density, resistivity, spontaneous potential, Vibroseis, 3-D velocity, neutron, and gamma-ray logs
Role of MRI in hip fractures, including stress fractures, occult fractures, avulsion fractures

International Nuclear Information System (INIS)

Nachtrab, O.; Cassar-Pullicino, V.N.; Lalam, R.; Tins, B.; Tyrrell, P.N.M.; Singh, J.

2012-01-01

MR imaging plays a vital role in the diagnosis and management of hip fractures in all age groups, in a large spectrum of patient groups spanning the elderly and sporting population. It allows a confident exclusion of fracture, differentiation of bony from soft tissue injury and an early confident detection of fractures. There is a spectrum of MR findings which in part is dictated by the type and cause of the fracture which the radiologist needs to be familiar with. Judicious but prompt utilisation of MR in patients with suspected hip fractures has a positive therapeutic impact with healthcare cost benefits as well as social care benefits.
Paratrooper's ankle fracture: posterior malleolar fracture.

Science.gov (United States)

Young, Ki Won; Kim, Jin-su; Cho, Jae Ho; Kim, Hyung Seuk; Cho, Hun Ki; Lee, Kyung Tai

2015-03-01

We assessed the frequency and types of ankle fractures that frequently occur during parachute landings of special operation unit personnel and analyzed the causes. Fifty-six members of the special force brigade of the military who had sustained ankle fractures during parachute landings between January 2005 and April 2010 were retrospectively analyzed. The injury sites and fracture sites were identified and the fracture types were categorized by the Lauge-Hansen and Weber classifications. Follow-up surveys were performed with respect to the American Orthopedic Foot and Ankle Society ankle-hindfoot score, patient satisfaction, and return to preinjury activity. The patients were all males with a mean age of 23.6 years. There were 28 right and 28 left ankle fractures. Twenty-two patients had simple fractures and 34 patients had comminuted fractures. The average number of injury and fractures sites per person was 2.07 (116 injuries including a syndesmosis injury and a deltoid injury) and 1.75 (98 fracture sites), respectively. Twenty-three cases (41.07%) were accompanied by posterior malleolar fractures. Fifty-five patients underwent surgery; of these, 30 had plate internal fixations. Weber type A, B, and C fractures were found in 4, 38, and 14 cases, respectively. Based on the Lauge-Hansen classification, supination-external rotation injuries were found in 20 cases, supination-adduction injuries in 22 cases, pronation-external rotation injuries in 11 cases, tibiofibular fractures in 2 cases, and simple medial malleolar fractures in 2 cases. The mean follow-up period was 23.8 months, and the average follow-up American Orthopedic Foot and Ankle Society ankle-hindfoot score was 85.42. Forty-five patients (80.36%) reported excellent or good satisfaction with the outcome. Posterior malleolar fractures occurred in 41.07% of ankle fractures sustained in parachute landings. Because most of the ankle fractures in parachute injuries were compound fractures, most cases had to
Investigated conductive fracture in the granitic rocks by flow-meter logging

International Nuclear Information System (INIS)

Ogata, Nobuhisa; Koide, Kaoru; Takeichi, Atsushi

1997-01-01

Test of the use of a measurement technique for the hydraulic conductivity of geological structures which act as flow paths or are impermeable to groundwater flow. In order to prove the value of flow-meter logging as an in-situ technique for detecting conductive fractures in granitic rocks, the method has been applied to a borehole near the Tono uranium mine, Gifu, Japan. This study in involved with detecting a conductive fracture and calculating the hydraulic conductivities. The results were as follows: (1) In a zone of groundwater inflow into the borehole, the hydraulic conductivity was calculated to be of the order of the 10 -3 - 10 -4 (cm/sec) from flow-meter logging. This value agreed with the results of a in-situ borehole permeability test carried out with a similar depth interval. (2) The study showed that flow-meter logging is effective for detecting the distribution of high conductivity fractures and calculating the hydraulic conductivity. (author)
Measuring the initial earth pressure of granite using hydraulic fracturing test; Goseong and Yuseong areas

Energy Technology Data Exchange (ETDEWEB)

Park, Byoung Yoon; Bae, Dae Seok; Kim, Chun Soo; Kim, Kyung Su; Koh, Young Kwon; Won, Kyung Sik [Korea Atomic Energy Research Institute, Taejeon (Korea)

2002-02-01

This report provides the initial earth pressure of granitic rocks obtained from Deep Core Drilling Program which is carried out as part of the assessment of deep geological environmental condition. These data are obtained by hydraulic fracturing test in three boreholes drilled up to 350{approx}500 m depth at the Yuseong and Goseong sites. These sites were selected based on the result of preliminary site evaluation study. The boreholes are NX-size (76 mm) and vertical. The procedure of hydraulic fracturing test is as follows: - Selecting the testing positions by preliminary investigation using BHTV logging. - Performing the hydraulic fracturing test at each selected position with depth.- Estimating the shut-in pressure by the bilinear pressure-decay-rate method. - Estimating the fracture reopening pressure from the pressure-time curves.- Estimating the horizontal principal stresses and the direction of principal stresses. 65 refs., 39 figs., 12 tabs. (Author)
Pressure grouting of fractured basalt flows

International Nuclear Information System (INIS)

Shaw, P.; Weidner, J.; Phillips, S.; Alexander, J.

1996-04-01

This report describes a field trial of pressure grouting in basalt and the results of subsequent coring and permeability measurement activities. The objective was to show that the hydraulic conductivity of fractured basalt bedrock can be significantly reduced by pressure injection of cementitious materials. The effectiveness of the pressure grout procedure was evaluated by measuring the change in the hydraulic conductivity of the bedrock. The extent of grout penetration was established by analyzing postgrout injection drilling chips for the presence of a tracer in the grout and also by examining cores of the treated basalt. Downhole radar mapping was used to establish major lava flow patterns and follow water movement during a surface infiltration test. A site called Box Canyon, which is located northwest of the INEL, was chosen for this study due to the similarity of this surface outcrop geology to that of the underlying bedrock fracture system found at the Radioactive Waste Management Complex. This study showed that hydraulic conductivity of basalt can be reduced through pressure grouting of cementitious material
Pressure grouting of fractured basalt flows

Energy Technology Data Exchange (ETDEWEB)

Shaw, P.; Weidner, J.; Phillips, S.; Alexander, J.

1996-04-01

This report describes a field trial of pressure grouting in basalt and the results of subsequent coring and permeability measurement activities. The objective was to show that the hydraulic conductivity of fractured basalt bedrock can be significantly reduced by pressure injection of cementitious materials. The effectiveness of the pressure grout procedure was evaluated by measuring the change in the hydraulic conductivity of the bedrock. The extent of grout penetration was established by analyzing postgrout injection drilling chips for the presence of a tracer in the grout and also by examining cores of the treated basalt. Downhole radar mapping was used to establish major lava flow patterns and follow water movement during a surface infiltration test. A site called Box Canyon, which is located northwest of the INEL, was chosen for this study due to the similarity of this surface outcrop geology to that of the underlying bedrock fracture system found at the Radioactive Waste Management Complex. This study showed that hydraulic conductivity of basalt can be reduced through pressure grouting of cementitious material.
Understanding brittle deformation at the Olkiluoto site. Literature compilation for site characterization and geological modelling

International Nuclear Information System (INIS)

Millnes, A.G.

2006-07-01

The present report arose from the belief that geological modelling at Olkiluoto, Finland, where an underground repository for spent nuclear fuel is at present under construction, could be significantly improved by an increased understanding of the phenomena being modelled, in conjunction with the more sophisticated data acquisition and processing methods which are now being introduced. Since the geological model is the necessary basis for the rock engineering and hydrological models, which in turn provide the foundation for identifying suitable rock volumes underground and for demonstrating longterm safety, its scientific basis is of critical importance. As a contribution to improving this scientific basis, the literature on brittle deformation in the Earth's crust has been reviewed, and key references chosen and arranged, with the particular geology of the Olkiluoto site in mind. The result is a compilation of scientific articles, reports and books on some of the key topics, which are of significance for an improved understanding of brittle deformation of hard, crystalline rocks, such as those typical for Olkiluoto. The report is subdivided into six Chapters, covering (1) background information, (2) important aspects of the fabric of intact rock, (3) fracture mechanics and brittle microtectonics, (4) fracture data acquisition and processing, for the statistical characterisation and modelling of fracture systems, (5) the characterisation of brittle deformation zones for deterministic modelling, and (6) the regional geological framework of the Olkiluoto site. The Chapters are subdivided into a number of Sections, and each Section into a number of Topics. The citations are mainly collected under each Topic, embedded in a short explanatory text or listed chronologically without comment. The systematic arrangement of Chapters, Sections and Topics is such that the Table of Contents can be used to focus quickly on the theme of interest without the necessity of looking
Geologic fracturing method and resulting fractured geologic structure

Science.gov (United States)

Mace, Jonathan L.; Bradley, Christopher R.; Greening, Doran R.; Steedman, David W.

2016-11-08

Detonation control modules and detonation control circuits are provided herein. A trigger input signal can cause a detonation control module to trigger a detonator. A detonation control module can include a timing circuit, a light-producing diode such as a laser diode, an optically triggered diode, and a high-voltage capacitor. The trigger input signal can activate the timing circuit. The timing circuit can control activation of the light-producing diode. Activation of the light-producing diode illuminates and activates the optically triggered diode. The optically triggered diode can be coupled between the high-voltage capacitor and the detonator. Activation of the optically triggered diode causes a power pulse to be released from the high-voltage capacitor that triggers the detonator.

The use of synthetic colloids in tracer transport experiments in saturated rock fractures

International Nuclear Information System (INIS)

Reimus, P.W.

1995-08-01

Studies of groundwater flow and contaminant transport in saturated, fractured geologic media are of great interest to researchers studying the potential long-term storage of hazardous wastes in or near such media. A popular technique for conducting such studies is to introduce tracers having different chemical and physical properties into a system and then observe the tracers at one or more downstream locations, inferring flow and transport mechanisms from the breakthrough characteristics of the different tracers. Many tracer studies have been conducted in saturated, fractured media to help develop and/or refine models capable of predicting contaminant transport over large scales in such media
Engineering Geology | Alaska Division of Geological & Geophysical Surveys

Science.gov (United States)

Alaska's Mineral Industry Reports AKGeology.info Rare Earth Elements WebGeochem Engineering Geology Alaska content Engineering Geology Additional information Engineering Geology Posters and Presentations Alaska Alaska MAPTEACH Tsunami Inundation Mapping Engineering Geology Staff Projects The Engineering Geology
Solute transport in fractured rock - applications to radionuclide waste repositories

International Nuclear Information System (INIS)

Neretnieks, I.

1990-12-01

Flow and solute transport in fractured rocks has been intensively studied in the last decade. The increased interest is mainly due to the plans in many countries to site repositories for high level nuclear waste in deep geologic formations. All investigated crystalline rocks have been found to be fractured and most of the water flows in the fractures and fracture zones. The water transports dissolved species and radionuclides. It is thus of interest to be able to understand and to do predictive modelling of the flowrate of water, the flowpaths and the residence times of the water and of the nuclides. The dissolved species including the nuclides will interact with the surrounding rock in different ways and will in many cases be strongly retarded relative to the water velocity. Ionic species may be ion exchanged or sorbed in the mineral surfaces. Charges and neutral species may diffuse into the stagnant waters in the rock matrix and thus be withdrawn from the mobile water. These effects will be strongly dependent on how much rock surface is in contact with the flowing water. It has been found in a set of field experiments and by other observations that not all fractures conduct water. Furthermore it is found that conductive fractures only conduct the water in a small part of the fracture in what is called channels or preferential flowpaths. This report summarizes the present concepts of water flow and solute transport in fractured rocks. The data needs for predictive modelling are discussed and both field and laboratory measurement which have been used to obtain data are described. Several large scale field experiments which have been specially designed to study flow and tracer transport in crystalline rocks are described. In many of the field experients new techniques have been developed and used. (81 refs.) (author)
Study to optimize a disposal tunnel layout taking into account heterogeneous characteristics of the geological environment

International Nuclear Information System (INIS)

Suyama, Yasuhiro; Toida, Masaru; Yanagizawa, Koichi

2007-01-01

The geological environment has spatially heterogeneous characteristics with varied host rock types, fractures and so on. In this case the generic disposal tunnel layout, which has been designed by JNC, is not the most suitable for HLW disposal in Japan. The existence of spatially heterogeneous characteristics means that in the repository region there exist sub-regions that are more favorable from the perspective of long-term safety and ones that are less favorable. In order that the spatially heterogeneous environment itself may be utilized most effectively as an NBS, an alternative design of disposal tunnel layout is required. Focusing on the geological environment with spatially heterogeneous characteristics, the authors have developed an alternative design of disposal tunnel layout. The alternative design adopts an optimization approach using a 'variable disposal tunnel layout'. The optimization approach minimizes the number of locations where major water conducting fractures are intersected, and maximizes the number of emplacement locations for waste packages. This paper will outline the variable disposal tunnel layout and its applicability. (author)
Fracture Mechanics

International Nuclear Information System (INIS)

Jang, Dong Il; Jeong, Gyeong Seop; Han, Min Gu

1992-08-01

This book introduces basic theory and analytical solution of fracture mechanics, linear fracture mechanics, non-linear fracture mechanics, dynamic fracture mechanics, environmental fracture and fatigue fracture, application on design fracture mechanics, application on analysis of structural safety, engineering approach method on fracture mechanics, stochastic fracture mechanics, numerical analysis code and fracture toughness test and fracture toughness data. It gives descriptions of fracture mechanics to theory and analysis from application of engineering.
An integrated structural and geochemical study of fracture aperture growth in the Campito Formation of eastern California

Science.gov (United States)

Doungkaew, N.; Eichhubl, P.

2015-12-01

Processes of fracture formation control flow of fluid in the subsurface and the mechanical properties of the brittle crust. Understanding of fundamental fracture growth mechanisms is essential for understanding fracture formation and cementation in chemically reactive systems with implications for seismic and aseismic fault and fracture processes, migration of hydrocarbons, long-term CO2 storage, and geothermal energy production. A recent study on crack-seal veins in deeply buried sandstone of east Texas provided evidence for non-linear fracture growth, which is indicated by non-elliptical kinematic fracture aperture profiles. We hypothesize that similar non-linear fracture growth also occurs in other geologic settings, including under higher temperature where solution-precipitation reactions are kinetically favored. To test this hypothesis, we investigate processes of fracture growth in quartzitic sandstone of the Campito Formation, eastern California, by combining field structural observations, thin section petrography, and fluid inclusion microthermometry. Fracture aperture profile measurements of cemented opening-mode fractures show both elliptical and non-elliptical kinematic aperture profiles. In general, fractures that contain fibrous crack-seal cement have elliptical aperture profiles. Fractures filled with blocky cement have linear aperture profiles. Elliptical fracture aperture profiles are consistent with linear-elastic or plastic fracture mechanics. Linear aperture profiles may reflect aperture growth controlled by solution-precipitation creep, with the aperture distribution controlled by solution-precipitation kinetics. We hypothesize that synkinematic crack-seal cement preserves the elliptical aperture profiles of elastic fracture opening increments. Blocky cement, on the other hand, may form postkinematically relative to fracture opening, with fracture opening accommodated by continuous solution-precipitation creep.
Geologic framework and Cenozoic evolution of the Yucca Mountain area, Nevada

International Nuclear Information System (INIS)

Fox, K.F. Jr.; Spengler, R.W.; Myers, W.B.

1990-01-01

Yucca Mountain, Nevada, has been proposed as the site of a high-level nuclear waste repository. The purpose of this paper is to outline aspects of the geology and tectonics of the area which bear on its suitability as a waste repository. The repository is to be excavated from a non-lithophysal zone within the lower part of the Paintbrush Tuff. Revised estimates of the thickness of this zone indicate that the lower, down-dip extremity of the planned repository could be raised by as much as 130 m, thus reducing the grade within the repository and increasing the distance to the water table below. We note that because of the closely spaced fracturing and low in-situ stresses within the repository block, lateral support of fractured rock is likely to be poor. 30 refs., 5 figs
Contamination in fractured-rock aquifers: Research at the former Naval Air Warfare Center, West Trenton, New Jersey

Science.gov (United States)

Goode, Daniel J.; Tiedeman, Claire; Lacombe, Pierre J.; Imbrigiotta, Thomas E.; Shapiro, Allen M.; Chapelle, Francis H.

2007-01-01

The U.S. Geological Survey and cooperators are studying chlorinated solvents in a fractured sedimentary rock aquifer underlying the former Naval Air Warfare Center (NAWC), West Trenton, New Jersey. Fractured-rock aquifers are common in many parts of the United States and are highly susceptible to contamination, particularly at industrial sites. Compared to 'unconsolidated' aquifers, there can be much more uncertainty about the direction and rate of contaminant migration and about the processes and factors that control chemical and microbial transformations of contaminants. Research at the NAWC is improving understanding of the transport and fate of chlorinated solvents in fractured-rock aquifers and will compare the effectiveness of different strategies for contaminant remediation.
Parallel, Multigrid Finite Element Simulator for Fractured/Faulted and Other Complex Reservoirs based on Common Component Architecture (CCA)

Energy Technology Data Exchange (ETDEWEB)

Milind Deo; Chung-Kan Huang; Huabing Wang

2008-08-31

Black-oil, compositional and thermal simulators have been developed to address different physical processes in reservoir simulation. A number of different types of discretization methods have also been proposed to address issues related to representing the complex reservoir geometry. These methods are more significant for fractured reservoirs where the geometry can be particularly challenging. In this project, a general modular framework for reservoir simulation was developed, wherein the physical models were efficiently decoupled from the discretization methods. This made it possible to couple any discretization method with different physical models. Oil characterization methods are becoming increasingly sophisticated, and it is possible to construct geologically constrained models of faulted/fractured reservoirs. Discrete Fracture Network (DFN) simulation provides the option of performing multiphase calculations on spatially explicit, geologically feasible fracture sets. Multiphase DFN simulations of and sensitivity studies on a wide variety of fracture networks created using fracture creation/simulation programs was undertaken in the first part of this project. This involved creating interfaces to seamlessly convert the fracture characterization information into simulator input, grid the complex geometry, perform the simulations, and analyze and visualize results. Benchmarking and comparison with conventional simulators was also a component of this work. After demonstration of the fact that multiphase simulations can be carried out on complex fracture networks, quantitative effects of the heterogeneity of fracture properties were evaluated. Reservoirs are populated with fractures of several different scales and properties. A multiscale fracture modeling study was undertaken and the effects of heterogeneity and storage on water displacement dynamics in fractured basements were investigated. In gravity-dominated systems, more oil could be recovered at a given pore
Characterizing and modelling the radionuclide transport properties of fracture zones in plutonic rocks of the Canadian Shield

International Nuclear Information System (INIS)

Davison, C.C.; Kozak, E.T.; Frost, L.H.; Everitt, R.A.; Brown, A.; Gascoyne, M.; Scheier, N.W.

1999-01-01

Plutonic rocks of the Canadian Shield were investigated as a potential host medium for nuclear fuel waste disposal of used CANDU nuclear fuel. Field investigations at several geologic research areas on the Shield have shown that major fracture zones are the dominant pathways for the large scale movement of groundwater and solutes through plutonic rock bodies. Because of this, a significant amount of the geoscience work has focused on methods to identify, characterize and model the radionuclide transport properties of major fracture zones in the fractured plutonic rocks of the Shield. In order to quantify the transport properties of such fracture zones a series of, groundwater tracer tests were performed over a period of several years in several major, low dipping fracture zones. Sixteen tracer tests were performed using dipole recirculation methods to evaluate transport over distance scales ranging from 17 m to 700 m. It was concluded that only tracer tests can provide useful estimates of the effective porosity and dispersivity characteristics of these large fracture zones in plutonic rocks of the Canadian Shield. (author)
Geologic setting of diverse volcanic materials in northern Elysium Planitia, Mars

International Nuclear Information System (INIS)

Mouginis-Mark, P.J.

1990-01-01

Geologic mapping of high-resolution (30-50 m/pixel) Viking Orbiter images of northern Elysium Planitia has identified seven sites where current problems in martian volcanology, chronology, and stratigraphy can be resolved. These sites, which are discussed in the context of a potential Mars rover/sample return mission, would permit the following investigations: (1) the dating of Lower Amazonian lava flows from Elysium Mons (thereby providing absolute calibration for global crater size/frequency relative chronologies), (2) the petrologic investigation of long run-out lava flows, (3) the geologic interpretation of materials that may either be lava flows or lahar deposits, (4) the analysis of materials believed to be ash deposits produced by explosive eruptions of Hecates Tholus, and (5) the investigation of the stratigraphy of fractured terrain along the boundary between northern Elysium Planitia and southern Utopia Planitia. 63 refs
Hydrothermal fluid flow within a tectonically active rift-ridge transform junction: Tjörnes Fracture Zone, Iceland

Science.gov (United States)

Lupi, M.; Geiger, S.; Graham, C. M.

2010-05-01

We investigate the regional fluid flow dynamics in a highly faulted transform area, the Tjörnes Fracture Zone in northern Iceland which is characterized by steep geothermal gradients, hydrothermal activity, and strong seismicity. We simulate fluid flow within the Tjörnes Fracture Zone using a high-resolution model that was based on the available geological and geophysical data and has the aim to represent the complex geological structures and the thermodynamical processes that drive the regional fluid flow in a physically realistic way. Our results show that convective heat flow and mixing of cold and saline seawater with deep hydrothermal fluids controls the large-scale fluid flow. The distribution of faults has a strong influence on the local hydrodynamics by focusing flow around clusters of faults. This explains the nature of isolated upflow zones of hot hydrothermal fluids which are observed in the Tjörnes Fracture Zone. An important emergent characteristic of the regional fluid flow in the Tjörnes Fracture Zone are two separate flow systems: one in the sedimentary basins, comprising more vigorous convection, and one in the crystalline basement, which is dominated by conduction. These two flow systems yield fundamental insight into the connection between regional hydrothermal fluid flow and seismicity because they form the basis of a toggle switch mechanism that is thought to have caused the hydrogeochemical anomalies recorded at Húsavik before and after the 5.8 M earthquake in September 2002.
A state geological survey commitment to environmental geology - the Texas Bureau of Economic Geology

International Nuclear Information System (INIS)

Wermund, E.G.

1990-01-01

In several Texas environmental laws, the Bureau of Economic Geology is designated as a planning participant and review agency in the process of fulfilling environmental laws. Two examples are legislation on reclamation of surface mines and regulation of processing low level radioactive wastes. Also, the Bureau is the principal geological reviewer of all Environmental Assessments and Environmental Impact Statements which the Office of the Governor circulates for state review on all major developmental activities in Texas. The BEG continues its strong interest in environmental geology. In February 1988, it recommitted its Land Resources Laboratory, initiated in 1974, toward fulfilling needs of state, county, and city governments for consultation and research on environmental geologic problems. An editorial from another state geological survey would resemble the about description of texas work in environmental geology. State geological surveys have led federal agencies into many developments of environmental geology, complemented federal efforts in their evolution, and continued a strong commitment to the maintenance of a quality environment through innovative geologic studies
Groundwater flow and sorption processes in fractured rocks (I)

Energy Technology Data Exchange (ETDEWEB)

Kim, Won Young; Woo, Nam Chul; Yum, Byoung Woo; Choi, Young Sub; Chae, Byoung Kon; Kim, Jung Yul; Kim, Yoo Sung; Hyun, Hye Ja; Lee, Kil Yong; Lee, Seung Gu; Youn, Youn Yul; Choon, Sang Ki [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

1996-12-01

This study is objected to characterize groundwater flow and sorption processes of the contaminants (ground-water solutes) along the fractured crystalline rocks in Korea. Considering that crystalline rock mass is an essential condition for using underground space cannot be overemphasized the significance of the characterizing fractured crystalline rocks. the behavior of the groundwater contaminants is studied in related to the subsurface structure, and eventually a quantitative technique will be developed to evaluate the impacts of the contaminants on the subsurface environments. The study has been carried at the Samkwang mine area in the Chung-Nam Province. The site has Pre-Cambrian crystalline gneiss as a bedrock and the groundwater flow system through the bedrock fractures seemed to be understandable with the study on the subsurface geologic structure through the mining tunnels. Borehole tests included core logging, televiewer logging, constant pressure fixed interval length tests and tracer tests. The results is summarized as follows; 1) To determine the hydraulic parameters of the fractured rock, the transient flow analysis produce better results than the steady - state flow analysis. 2) Based on the relationship between fracture distribution and transmissivities measured, the shallow part of the system could be considered as a porous and continuous medium due to the well developed fractures and weathering. However, the deeper part shows flow characteristics of the fracture dominant system, satisfying the assumptions of the Cubic law. 3) Transmissivities from the FIL test were averaged to be 6.12 x 10{sup -7}{sub m}{sup 2}{sub /s}. 4) Tracer tests result indicates groundwater flow in the study area is controlled by the connection, extension and geometry of fractures in the bedrock. 5) Hydraulic conductivity of the tracer-test interval was in maximum of 7.2 x 10{sup -6}{sub m/sec}, and the effective porosity of 1.8 %. 6) Composition of the groundwater varies
Modeling reactive transport processes in fractured rock using the time domain random walk approach within a dual-porosity framework

Science.gov (United States)

Roubinet, D.; Russian, A.; Dentz, M.; Gouze, P.

2017-12-01

Characterizing and modeling hydrodynamic reactive transport in fractured rock are critical challenges for various research fields and applications including environmental remediation, geological storage, and energy production. To this end, we consider a recently developed time domain random walk (TDRW) approach, which is adapted to reproduce anomalous transport behaviors and capture heterogeneous structural and physical properties. This method is also very well suited to optimize numerical simulations by memory-shared massive parallelization and provide numerical results at various scales. So far, the TDRW approach has been applied for modeling advective-diffusive transport with mass transfer between mobile and immobile regions and simple (theoretical) reactions in heterogeneous porous media represented as single continuum domains. We extend this approach to dual-continuum representations considering a highly permeable fracture network embedded into a poorly permeable rock matrix with heterogeneous geochemical reactions occurring in both geological structures. The resulting numerical model enables us to extend the range of the modeled heterogeneity scales with an accurate representation of solute transport processes and no assumption on the Fickianity of these processes. The proposed model is compared to existing particle-based methods that are usually used to model reactive transport in fractured rocks assuming a homogeneous surrounding matrix, and is used to evaluate the impact of the matrix heterogeneity on the apparent reaction rates for different 2D and 3D simple-to-complex fracture network configurations.
Upscaling solute transport in naturally fractured porous media with the continuous time random walk method

Energy Technology Data Exchange (ETDEWEB)

Geiger, S.; Cortis, A.; Birkholzer, J.T.

2010-04-01

Solute transport in fractured porous media is typically 'non-Fickian'; that is, it is characterized by early breakthrough and long tailing and by nonlinear growth of the Green function-centered second moment. This behavior is due to the effects of (1) multirate diffusion occurring between the highly permeable fracture network and the low-permeability rock matrix, (2) a wide range of advection rates in the fractures and, possibly, the matrix as well, and (3) a range of path lengths. As a consequence, prediction of solute transport processes at the macroscale represents a formidable challenge. Classical dual-porosity (or mobile-immobile) approaches in conjunction with an advection-dispersion equation and macroscopic dispersivity commonly fail to predict breakthrough of fractured porous media accurately. It was recently demonstrated that the continuous time random walk (CTRW) method can be used as a generalized upscaling approach. Here we extend this work and use results from high-resolution finite element-finite volume-based simulations of solute transport in an outcrop analogue of a naturally fractured reservoir to calibrate the CTRW method by extracting a distribution of retention times. This procedure allows us to predict breakthrough at other model locations accurately and to gain significant insight into the nature of the fracture-matrix interaction in naturally fractured porous reservoirs with geologically realistic fracture geometries.
The Effect of Boiling on Seismic Properties of Water-Saturated Fractured Rock

Science.gov (United States)

Grab, Melchior; Quintal, Beatriz; Caspari, Eva; Deuber, Claudia; Maurer, Hansruedi; Greenhalgh, Stewart

2017-11-01

Seismic campaigns for exploring geothermal systems aim at detecting permeable formations in the subsurface and evaluating the energy state of the pore fluids. High-enthalpy geothermal resources are known to contain fluids ranging from liquid water up to liquid-vapor mixtures in regions where boiling occurs and, ultimately, to vapor-dominated fluids, for instance, if hot parts of the reservoir get depressurized during production. In this study, we implement the properties of single- and two-phase fluids into a numerical poroelastic model to compute frequency-dependent seismic velocities and attenuation factors of a fractured rock as a function of fluid state. Fluid properties are computed while considering that thermodynamic interaction between the fluid phases takes place. This leads to frequency-dependent fluid properties and fluid internal attenuation. As shown in a first example, if the fluid contains very small amounts of vapor, fluid internal attenuation is of similar magnitude as attenuation in fractured rock due to other mechanisms. In a second example, seismic properties of a fractured geothermal reservoir with spatially varying fluid properties are calculated. Using the resulting seismic properties as an input model, the seismic response of the reservoir is then computed while the hydrothermal structure is assumed to vary over time. The resulting seismograms demonstrate that anomalies in the seismic response due to fluid state variability are small compared to variations caused by geological background heterogeneity. However, the hydrothermal structure in the reservoir can be delineated from amplitude anomalies when the variations due to geology can be ruled out such as in time-lapse experiments.
Spatial pattern of groundwater arsenic occurrence and association with bedrock geology in greater augusta, maine

Science.gov (United States)

Yang, Q.; Jung, H.B.; Culbertson, C.W.; Marvinney, R.G.; Loiselle, M.C.; Locke, D.B.; Cheek, H.; Thibodeau, H.; Zheng, Yen

2009-01-01

In New England, groundwater arsenic occurrence has been linked to bedrock geology on regional scales. To ascertain and quantify this linkage at intermediate (100-101 km) scales, 790 groundwater samples from fractured bedrock aquifers in the greater Augusta, Maine area are analyzed, and 31% of the sampled wells have arsenic concentrations >10 ??g/L. The probability of [As] exceeding 10 ??g/L mapped by indicator kriging is highest in Silurian pelite-sandstone and pelite-limestone units (???40%). This probability differs significantly (p bedrock map. Thus, bedrock geology is associated with arsenic occurrence in fractured bedrock aquifers of the study area at intermediate scales relevant to water resources planning. The arsenic exceedance rate for each rock unit is considered robust because low, medium, and high arsenic occurrences in four cluster areas (3-20 km2) with a low sampling density of 1-6 wells per km2 are comparable to those with a greater density of 5-42 wells per km2. About 12,000 people (21% of the population) in the greater Augusta area (???1135 km2) are at risk of exposure to >10 ??g/L arsenic in groundwater. ?? 2009 American Chemical Society.
Facilitating the exploitation of ERTS imagery using snow enhancement techniques. [geological mapping of New England test area

Science.gov (United States)

Wobber, F. J.; Martin, K. R. (Principal Investigator); Amato, R. V.; Leshendok, T.

1974-01-01

The author has identified the following significant results. The procedure for conducting a regional geological mapping program utilizing snow-enhanced ERTS-1 imagery has been summarized. While it is recognized that mapping procedures in geological programs will vary from area to area and from geologist to geologist, it is believed that the procedure tested in this project is applicable over a wide range of mapping programs. The procedure is designed to maximize the utility and value of ERTS-1 imagery and aerial photography within the initial phase of geological mapping programs. Sample products which represent interim steps in the mapping formula (e.g. the ERTS Fracture-Lineament Map) have been prepared. A full account of these procedures and products will be included within the Snow Enhancement Users Manual.
Experiments and Simulations of Fluid Flow in Heterogeneous Reservoir Models - Emphasis on Impacts from Crossbeds and Fractures

Energy Technology Data Exchange (ETDEWEB)

Boerresen, Knut Arne

1996-12-31

Hydrocarbon recovery from subsurface reservoirs has become increasingly dependent on advanced recovery techniques that require improved understanding of the physics of fluid flow within and across geological units including small-scale heterogeneities and fractures. In this thesis, impacts from heterogeneities on local fluid flow are studied experimentally by means of imaging techniques to visualize fluid flow in two dimensions during flooding of larger reservoir models. Part 1 reflects the multi-disciplinary collaboration, by briefly introducing the relevant geology, the literature on experiments on fluid flow in bedded structures, and outlining the applied numerical simulator and imaging techniques applied to visualize fluid flow. The second part contains a synopsis of displacement experiments in naturally laminated sandstones and in crossbed laboratory models, and of the impact from incipient shear fractures on oil recovery. The detailed results obtained from the experiments and simulations are described in six papers, all included. 215 refs., 108 figs., 16 tabs.

Experiments and Simulations of Fluid Flow in Heterogeneous Reservoir Models - Emphasis on Impacts from Crossbeds and Fractures

Energy Technology Data Exchange (ETDEWEB)

Boerresen, Knut Arne

1997-12-31

Hydrocarbon recovery from subsurface reservoirs has become increasingly dependent on advanced recovery techniques that require improved understanding of the physics of fluid flow within and across geological units including small-scale heterogeneities and fractures. In this thesis, impacts from heterogeneities on local fluid flow are studied experimentally by means of imaging techniques to visualize fluid flow in two dimensions during flooding of larger reservoir models. Part 1 reflects the multi-disciplinary collaboration, by briefly introducing the relevant geology, the literature on experiments on fluid flow in bedded structures, and outlining the applied numerical simulator and imaging techniques applied to visualize fluid flow. The second part contains a synopsis of displacement experiments in naturally laminated sandstones and in crossbed laboratory models, and of the impact from incipient shear fractures on oil recovery. The detailed results obtained from the experiments and simulations are described in six papers, all included. 215 refs., 108 figs., 16 tabs.
Semianalytical Solutions of Radioactive or Reactive Transport in Variably-Fractured Layered Media: 1. Solutes

International Nuclear Information System (INIS)

George J. Moridis

2001-01-01

In this paper, semianalytical solutions are developed for the problem of transport of radioactive or reactive solute tracers through a layered system of heterogeneous fractured media with misaligned fractures. The tracer transport equations in the non-flowing matrix account for (a) diffusion, (b) surface diffusion, (c) mass transfer between the mobile and immobile water fractions, (d) linear kinetic or equilibrium physical, chemical, or combined solute sorption or colloid filtration, and (e) radioactive decay or first-order chemical reactions. The tracer-transport equations in the fractures account for the same processes, in addition to advection and hydrodynamic dispersion. Any number of radioactive decay daughter products (or products of a linear, first-order reaction chain) can be tracked. The solutions, which are analytical in the Laplace space, are numerically inverted to provide the solution in time and can accommodate any number of fractured and/or porous layers. The solutions are verified using analytical solutions for limiting cases of solute and colloid transport through fractured and porous media. The effect of important parameters on the transport of 3 H, 237 Np and 239 Pu (and its daughters) is investigated in several test problems involving layered geological systems of varying complexity
Joint location and source mechanism inversion of microseismic events: benchmarking on seismicity induced by hydraulic fracturing

Czech Academy of Sciences Publication Activity Database

Anikiev, D.; Valenta, Jan; Staněk, František; Eisner, Leo

2014-01-01

Roč. 198, č. 1 (2014), s. 249-258 ISSN 0956-540X R&D Projects: GA ČR GAP210/12/2451 Institutional support: RVO:67985891 Keywords : inverse theory * probability distributions * wave scattering and diffraction * fractures and faults Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.724, year: 2013
Hydrogeologic framework of fractured sedimentary rock, Newark Basin, New Jersey

Science.gov (United States)

Lacombe, Pierre J.; Burton, William C.

2010-01-01

The hydrogeologic framework of fractured sedimentary bedrock at the former Naval Air Warfare Center (NAWC), Trenton, New Jersey, a trichloroethylene (TCE)-contaminated site in the Newark Basin, is developed using an understanding of the geologic history of the strata, gamma-ray logs, and rock cores. NAWC is the newest field research site established as part of the U.S. Geological Survey Toxic Substances Hydrology Program, Department of Defense (DoD) Strategic Environmental Research and Development Program, and DoD Environmental Security Technology Certification Program to investigate contaminant remediation in fractured rock. Sedimentary bedrock at the NAWC research site comprises the Skunk Hollow, Byram, and Ewing Creek Members of the Lockatong Formation and Raven Rock Member of the Stockton Formation. Muds of the Lockatong Formation that were deposited in Van Houten cycles during the Triassic have lithified to form the bedrock that is typical of much of the Newark Basin. Four lithotypes formed from the sediments include black, carbon-rich laminated mudstone, dark-gray laminated mudstone, light-gray massive mudstone, and red massive mudstone. Diagenesis, tectonic compression, off-loading, and weathering have altered the rocks to give some strata greater hydraulic conductivity than other strata. Each stratum in the Lockatong Formation is 0.3 to 8 m thick, strikes N65 degrees E, and dips 25 degrees to 70 degrees NW. The black, carbon-rich laminated mudstone tends to fracture easily, has a relatively high hydraulic conductivity and is associated with high natural gamma-ray count rates. The dark-gray laminated mudstone is less fractured and has a lower hydraulic conductivity than the black carbon-rich laminated mudstone. The light-gray and the red massive mudstones are highly indurated and tend to have the least fractures and a low hydraulic conductivity. The differences in gamma-ray count rates for different mudstones allow gamma-ray logs to be used to correlate and
WIPP site and vicinity geological field trip

International Nuclear Information System (INIS)

Chaturvedi, L.

1980-10-01

The Environmental Evaluation Group is conducting an assessment of the radiological health risks to people from the Waste Isolation Pilot Plant. As a part of this work, EEG is making an effort to improve the understanding of those geological issues concerning the WIPP site which may affect the radiological consequences of the proposed repository. One of the important geological issues to be resolved is the timing and the nature of the dissolution processes which may have affected the WIPP site. EEG organized a two-day conference of geological scientists, on January 17-18, 1980. On the basis of the January conference and the June field trip, EEG has formed the following conclusions: (1) it has not been clearly established that the site or the surrounding area has been attacked by deep dissolution to render it unsuitable for the nuclear waste pilot repository; (2) the existence of an isolated breccia pipe at the site unaccompanied by a deep dissolution wedge, is a very remote possibility; (3) more specific information about the origin and the nature of the brine reservoirs is needed. An important question that should be resolved is whether each encounter with artesian brine represents a separate pocket or whether these occurrences are interconnected; (4) Anderson has postulated a major tectonic fault or a fracture system at the Basin margin along the San Simon Swale; (5) the area in the northern part of the WIPP site, identified from geophysical and bore hole data as the disturbed zone, should be further investigated to cleary understand the nature and significance of this structural anomaly; and (6) a major drawback encountered during the discussions of geological issues related to the WIPP site is the absence of published material that brings together all the known information related to a particular issue
Model of T-Type Fracture in Coal Fracturing and Analysis of Influence Factors of Fracture Morphology

Directory of Open Access Journals (Sweden)

Yuwei Li

2018-05-01

Full Text Available Special T-type fractures can be formed when coal is hydraulically fractured and there is currently no relevant theoretical model to calculate and describe them. This paper first establishes the height calculation model of vertical fractures in multi-layered formations and deduces the stress intensity factor (SIF at the upper and lower sides of the fracture in the process of vertical fracture extension. Combined with the fracture tip stress analysis method of fracture mechanics theory, the horizontal bedding is taken into account for tensile and shear failure, and the critical mechanical conditions for the formation of horizontal fracture in coal are obtained. Finally, the model of T-type fracture in coal fracturing is established, and it is verified by fracturing simulation experiments. The model calculation result shows that the increase of vertical fracture height facilitates the increase of horizontal fracture length. The fracture toughness of coal has a significant influence on the length of horizontal fracture and there is a threshold. When the fracture toughness is less than the threshold, the length of horizontal fracture remains unchanged, otherwise, the length of horizontal fracture increases rapidly with the increase of fracture toughness. When the shear strength of the interface between the coalbed and the interlayer increases, the length of the horizontal fracture of the T-type fracture rapidly decreases.
Hydrogen transfer experiments and modelization in clay rocks for radioactive waste deep geological repository

International Nuclear Information System (INIS)

Boulin, P.

2008-10-01

Gases will be generated by corrosion of high radioactive waste containers in deep geological repositories. A gas phase will be generated. Gas pressure will build up and penetrated the geological formation. If gases do not penetrate the geological barrier efficiently, the pressure build up may create a risk of fracturing and of creation of preferential pathways for radionuclide migration. The present work focuses on Callovo-Oxfordian argillites characterisation. An experiment, designed to measure very low permeabilities, was used with hydrogen/helium and analysed using the Dusty Gas Model. Argillites close to saturation have an accessible porosity to gas transfer that is lower than 0,1% to 1% of the porosity. Analysis of the Knudsen effect suggests that this accessible network should be made of 50 nm to 200 nm diameter pores. The permeabilities values were integrated to an ANDRA operating model. The model showed that the maximum pressure expected near the repository would be 83 bar. (author)
Geophysical and geological borehole investigations for the characterization of a site for radioactive waste disposal

International Nuclear Information System (INIS)

Olsson, O.; Ahlbom, K.

1984-02-01

In the Swedish program for site investigations detailed geological and geophysical investigations are performed at areas of 4-6 km 2 at the surface. Normally around 10 deep core bore holes are drilled. The length of the holes is normally from 600 to 1000 m. The holes are drilled to verify the location of fracture zones and to investigate the physical and hydraulic properties of the fracture zones at large depths. Investigations have been performed in a number of sites with mainly granitic and gneissic rocks. The core from these boreholes is logged with the aid of a microcomputer system. The cores are mapped with respect to rock type, structure, fractures and fracture minerals. Indications of water flow, shearing and core-discing are also studied. The boreholes are logged with a suite of geophysical logs. Several different electrical logs are used and have been found to be good indicators of fracture zones. Normally the electrical logs in combination with the fracture frequency are used to define the limits of fracture zones crossing the borehole. The temperature log and the salinity log have proved to be good indicators of permeable zones. The data from each hole is correlated with data obtained from the other holes and the surface investigations to build a fracture zone model which is used for the hydraulic modelling of the site. In order to verify the extension of the fracture zones at a distance from the borehole cross-hole techniques have been applied. At the Swedish test site Finnsjoe and in the Stripa mine the suitability of the mise a la masse technique for mapping of fracture zones was tested. At the Finnsjoe site it was possible to map a fairly complex fracture system over distances up to 150 m. In the Stripa mine the object was to follow the extent of a major fracture zone for distances up to 600 m. It was possible to obtain an indication of the orientation of the fracture zone
Mineral Precipitation in Fractures: Multiscale Imaging and Geochemical Modeling

Science.gov (United States)

Hajirezaie, S.; Peters, C. A.; Swift, A.; Sheets, J. M.; Cole, D. R.; Crandall, D.; Cheshire, M.; Stack, A. G.; Anovitz, L. M.

2017-12-01

For subsurface energy technologies such as geologic carbon sequestration, fractures are potential pathways for fluid migration from target formations. Highly permeable fractures may become sealed by mineral precipitation. In this study, we examined shale specimens with existing cemented fractures as natural analogues, using an array of imaging methods to characterize mineralogy and porosity at several spatial scales. In addition, we used reactive transport modeling to investigate geochemical conditions that can lead to extensive mineral precipitation and to simulate the impacts on fracture hydraulic properties. The naturally-cemented fractured rock specimens were from the Upper Wolfcamp formation in Texas, at 10,000 ft depth. The specimens were scanned using x-ray computed tomography (xCT) at resolution of 13 microns. The xCT images revealed an original fracture aperture of 1.9 mm filled with several distinct mineral phases and vuggy void regions, and the mineral phase volumes and surface areas were quantified and mapped in 3D. Specimens were thin-sectioned and examined at micron- and submicron-scales using petrographic microscopy (PM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and small angle X-ray scattering (SAXS). Collectively these methods revealed crystals of dolomite as large as 900 microns in length overlain with a heterogeneous mixture of carbonate minerals including calcite, dolomite, and Fe-rich dolomite, interspersed at spatial scales as small as 5 microns. In addition, secondary precipitation of SiO2 was found to fill some of the void space. This multiscale imaging was used to inform the reactive transport modeling employed to examine the conditions that can cause the observed mineral precipitation in fractures at a larger scale. Two brines containing solutions that when mixed would lead to precipitation of various carbonate minerals were simulated as injectants into a fracture domain. In particular, the competing
Bedrock geology of snyderville basin: Structural geology techniques applied to understanding the hydrogeology of a rapidly developing region, Summit County, Utah

Science.gov (United States)

Keighley, K.E.; Yonkee, W.A.; Ashland, F.X.; Evans, J.P.

1997-01-01

The availability of ground water is a problem for many communities throughout the west. As these communities continue to experience growth, the initial allocation of ground water supplies proves inadequate and may force restrictions on existing, and future, development plans. Much of this new growth relies on ground water supplies extracted from fractured bedrock aquifers. An example of a community faced with this problem is western Summit County, near Park City, Utah, This area has experienced significant water shortages coupled with a 50% growth rate in the past 10-15 years. Recent housing development rests directly on complexly deformed Triassic to Jurassic sedimentary rocks in the hanging wall of the Mount Raymond-Absaroka thrust system. The primary fractured bedrock aquifers are the Nugget Sandstone, and limestones in the Thaynes and Twin Creek Formations. Ground water production and management strategies can be improved if the geometry of the structures and the flow properties of the fractured and folded bedrock can be established. We characterize the structures that may influence ground water flow at two sites: the Pinebrook and Summit Park subdivisions, which demonstrate abrupt changes (less than 1 mi/1.6 km) within the hydrogeologic systems. Geologic mapping at scales of 1:4500 (Pinebrook) and 1:9600 (Summit Park), scanline fracture mapping at the outcrop scale, geologic cross sections, water well data, and structural analysis, provides a clearer picture of the hydrogeologic setting of the aquifers in this region, and has been used to successfully site wells. In the Pinebrook area, the dominate map-scale structures of the area is the Twomile Canyon anticline, a faulted box-like to conical anticline. Widely variable bedding orientations suggest that the fold is segmented and is non-cylindrical and conical on the western limb with a fold axis that plunges to the northwest and also to the southeast, and forms a box-type fold between the middle and eastern
Discrete fracture network modelling of a KBS-3H repository at Olkiluoto

Energy Technology Data Exchange (ETDEWEB)

Lanyon, G.W. (Fracture Systems Ltd, St Ives (United Kingdom)); Marschall, P. (Nagra, Wettingen (Switzerland))

2008-06-15

This report presents Discrete Fracture Network (DFN) models of groundwater flow around a KBS-3H repository situated at Olkiluoto. The study was performed in support of the Safety Case for the KBS-3H Concept, being jointly studied by SKB and Posiva. As part of the preliminary assessment of long term safety of a KBS-3H repository, a Process Report and an Evolution Report (evolution of the disposal system from the emplacement of the first canister to the long term) are being produced. In the course of the task definition the project team identified the need for complementary modelling studies aimed at increasing insight into the hydrodynamic evolution of the disposal system after waste emplacement. In particular, the following issues were identified as requiring input from hydrodynamic models: Probability of high inflow points which may cause buffer erosion. Time transients of inflows after construction of deposition drifts. Interference between deposition drifts and transport tunnels. The DFN models represent the fault and fracture system in the planned repository volume at Olkiluoto. In particular, they represent the hydro geologically significant features. The types of hydrogeological features included in the models are: Major Fracture Zones (MFZs). Local Fracture Zones (LFZs) and associated water conducting features (LFZ-WCFs). Water Conducting Features in the background rock (BR-WCFs). These feature types are derived from the current geological and hydrogeological interpretations developed by Posiva. Several model variants were developed during the study and these variants were used for geometric simulations of the WCF network around the deposition drifts. A simple layout adaptation scheme has been applied to the network models to derive statistics for performance measures relating to the deposition drifts, compartments, plugs and super-containers. A single fracture transient flow model was developed to provide insight to transient flow behaviour around
Discrete fracture network modelling of a KBS-3H repository at Olkiluoto

International Nuclear Information System (INIS)

Lanyon, G.W.; Marschall, P.

2008-06-01

This report presents Discrete Fracture Network (DFN) models of groundwater flow around a KBS-3H repository situated at Olkiluoto. The study was performed in support of the Safety Case for the KBS-3H Concept, being jointly studied by SKB and Posiva. As part of the preliminary assessment of long term safety of a KBS-3H repository, a Process Report and an Evolution Report (evolution of the disposal system from the emplacement of the first canister to the long term) are being produced. In the course of the task definition the project team identified the need for complementary modelling studies aimed at increasing insight into the hydrodynamic evolution of the disposal system after waste emplacement. In particular, the following issues were identified as requiring input from hydrodynamic models: Probability of high inflow points which may cause buffer erosion. Time transients of inflows after construction of deposition drifts. Interference between deposition drifts and transport tunnels. The DFN models represent the fault and fracture system in the planned repository volume at Olkiluoto. In particular, they represent the hydro geologically significant features. The types of hydrogeological features included in the models are: Major Fracture Zones (MFZs). Local Fracture Zones (LFZs) and associated water conducting features (LFZ-WCFs). Water Conducting Features in the background rock (BR-WCFs). These feature types are derived from the current geological and hydrogeological interpretations developed by Posiva. Several model variants were developed during the study and these variants were used for geometric simulations of the WCF network around the deposition drifts. A simple layout adaptation scheme has been applied to the network models to derive statistics for performance measures relating to the deposition drifts, compartments, plugs and super-containers. A single fracture transient flow model was developed to provide insight to transient flow behaviour around
Geologic mapping of Northern Atla Regio on Venus: Preliminary data

Science.gov (United States)

Nikishin, A. M.; Burba, G. A.

1993-01-01

The Northern part of Atla Regio within the frame of C1-formate Magellan photo map 15N197 was mapped geologically at scale 1:8,000,000. This is a part of Russia's contribution into C1 geologic mapping efforts. The map is reproduced here being reduced about twice. The map shows that the Northern Atla area is predominantly a volcanic plain with numerous volcanic features: shield volcanoes, domes and hills with various morphology, corona-like constructions, radar bright and dark spots often with flow-like outlines. Relatively small areas of tessera occurred in the area are mainly semi-flooded with the plain material. Tesserae are considered to be the oldest terrains within the map sheet. There are many lineated terrains in the region. They are interpreted as the old, almost-buried tesserae (those with crossed lineaments) or partly buried ridge belts (those with parallel lineaments). These lineated terrains have an intermediate age between the young volcanic plains and the old tessera areas. Two prominent high volcanic shields are located within the region - Ozza Mons and Sapas Mona. The most prominent structure in Northern Atla is Ganis Chasma rift. The rift cuts volcanic plain and is considered to be under formation during approximately the same time with Ozza Mons shield. Ganis Chasma rift valley is highly fractured and bounded with fault scarps. Rift shoulder uplifts are typical for Ganis Chasma. There are few relatively young volcanic features inside the rift valley. The analysis of fracturing and rift valley geometry shows the rift originated due to 5-10 percent crustal extention followed by the crustal subsidence. The age sequence summary for the main terrain types in the region is (from older to younger ones): tesserae; lineated terrains with crossed lineaments; lineated terrains with parallel lineaments; volcanic plains; and prominent volcanic shields and Ganis Chasma rift valley. The geologic structure of Atla Regio as it appeared now with the Magellan high
Optimization of the key geological target parameters of shale-gas horizontal wells in the Changning Block, Sichuan Basin

Directory of Open Access Journals (Sweden)

Hongzhi Yang

2016-12-01

Full Text Available In recent years, great progress has been made in geologic evaluation, engineering test and development optimization of the Lower Cambrian Wufeng Fm–Lower Silurian Longmaxi Fm shale gas in the Sichuan Basin, and the main shale gas exploitation technologies have been understood preliminarily. In addition, scale productivity construction has been completed in Jiaoshiba, Changning and Weiyuan blocks. In this paper, the Wufeng Fm–Longmaxi Fm shale gas wells in Changning Block were taken as the study object to provide technical reference for the development design of similar shale-gas horizontal wells. The technology combining geology with engineering, dynamic with static, and statistical analysis with simulation prediction was applied to quantify the main factors controlling shale-gas well productivity, develop the shale-gas well production prediction model, and optimize the key technical parameters of geologic target of shale-gas horizontal wells in the block (e.g. roadway orientation, location and spacing, horizontal section length and gas well production index. In order to realize high productivity of shale gas wells, it is necessary to maximize the included angle between the horizontal section orientation and the maximum major stress and fracture development direction, deploy horizontal-well roadway in top-quality shale layers, and drill the horizontal section in type I reservoirs over 1000 m long. It is concluded that high productivity of shale gas wells is guaranteed by the horizontal-well wellbore integrity and the optimized low-viscosity slickwater and ceramsite fracturing technology for complex fracture creation. Based on the research results, the technical policies for shale gas development of Changning Block are prepared and a guidance and reference are provided for the shale gas development and productivity construction in the block and the development design of similar shale-gas horizontal wells.
Hydraulic Fracturing At Sedimentary Basin Scale Fracturation hydraulique à l'échelle des bassins sédimentaires

Directory of Open Access Journals (Sweden)

Schneider F.

2006-12-01

Full Text Available One key point for simulating the hydraulic fracturing at basin scale, is to be able to compute the stress tensor. This is generally not addressed in basin model because of the complexity of this problem. In order to get access to the stress tensor we have to assume that:- one of the principal stress is vertical and equals the overburden weight;- the horizontal stress is deduced from the vertical stress with the K0 coefficient that is a function of depth and of the tectonical setting. Consolidation is considered here as the combined effect of the mechanical compaction and the chemical compaction. The mechanical compaction is mainly caused by the rearrangement of grains during burial and could be represented at the macroscopical scale by an elastoplastic rheology. The chemical compaction is considered here as resulting from dissolution-precipitation mechanisms, generally induced by stress (pressure-solution. The chemical compaction could be represented at the macroscopical scale by a viscoplastic rheology. The complete elastoplastic yield is defined by the union of the consolidation elastoplastic yield and of the different failure criteria that could be seen as elastobrittle yields. Thus, the elastoplastic yield is composed of six elementary elastoplastic yields which define the onset of vertical compaction, horizontal compaction, vertical tensile fracturing, horizontal tensile fracturing, subvertical shear fracturing, and subhorizontal shear fracturing. Due to the consolidation, most of the parameters that describe the physical properties of the sediments evolve with the geological times. One difficulty is to quantify the degree of evolution of the porous medium during its geological history. Here, we have chosen to measure the evolution of the sediments by their porosity. The local simulations showed that fracturing may occur is numerous configurations. Some of these configurations indicate that the sediments can reach the limit of its elastic
Potential of semiautomated, synoptic geologic studies for characterization of hazardous waste sites

International Nuclear Information System (INIS)

Foley, M.G.; Beaver, D.E.; Glennon, M.A.; Eliason, J.R.

1988-01-01

Siting studies for licensing hazardous facilities require three-dimensional characterization of site geology including lithology, structure, and tectonics. The scope of these studies depends on the type of hazardous facility and its associated regulations. This scope can vary from a pro forma literature review to an extensive, multiyear research effort. Further, the regulatory environment often requires that the credibility of such studies be established in administrative and litigative proceedings, rather than solely by technical peer review. Pacific Northwest Laboratory (PNL) has developed a technology called remote geologic analysis (RGA). This technology provides reproducible photogeologic maps, determinations of three- dimensional faults and fracture sets expressed as erosional lineaments or planar topographic features, planar feature identification in seismic hypocenter data, and crustal- stress/tectonic analyses. Results from the RGA establish a foundation for interpretations that are defensible in licensing proceedings
Using microstructure observations to quantify fracture properties and improve reservoir simulations. Final report, September 1998

Energy Technology Data Exchange (ETDEWEB)

Laubach, S.E.; Marrett, R.; Rossen, W.; Olson, J.; Lake, L.; Ortega, O.; Gu, Y.; Reed, R.

1999-01-01

The research for this project provides new technology to understand and successfully characterize, predict, and simulate reservoir-scale fractures. Such fractures have worldwide importance because of their influence on successful extraction of resources. The scope of this project includes creation and testing of new methods to measure, interpret, and simulate reservoir fractures that overcome the challenge of inadequate sampling. The key to these methods is the use of microstructures as guides to the attributes of the large fractures that control reservoir behavior. One accomplishment of the project research is a demonstration that these microstructures can be reliably and inexpensively sampled. Specific goals of this project were to: create and test new methods of measuring attributes of reservoir-scale fractures, particularly as fluid conduits, and test the methods on samples from reservoirs; extrapolate structural attributes to the reservoir scale through rigorous mathematical techniques and help build accurate and useful 3-D models of the interwell region; and design new ways to incorporate geological and geophysical information into reservoir simulation and verify the accuracy by comparison with production data. New analytical methods developed in the project are leading to a more realistic characterization of fractured reservoir rocks. Testing diagnostic and predictive approaches was an integral part of the research, and several tests were successfully completed.
Two-phase flow in fractured rock

International Nuclear Information System (INIS)

Davies, P.; Long, J.; Zuidema, P.

1993-11-01

This report gives the results of a three-day workshop on two-phase flow in fractured rock. The workshop focused on two-phase flow processes that are important in geologic disposal of nuclear waste as experienced in a variety of repository settings. The goals and objectives of the workshop were threefold: exchange information; describe the current state of understanding; and identify research needs. The participants were divided into four subgroups. Each group was asked to address a series of two-phase flow processes. The following groups were defined to address these processes: basic flow processes; fracture/matrix interactions; complex flow processes; and coupled processes. For each process, the groups were asked to address these four issues: (1) describe the two-phase flow processes that are important with respect to repository performance; (2) describe how this process relates to the specific driving programmatic issues given above for nuclear waste storage; (3) evaluate the state of understanding for these processes; and (4) suggest additional research to address poorly understood processes relevant to repository performance. The reports from each of the four working groups are given here
Model of mechanical representation of the formation of natural fractures inside a petroleum reservoir; Modele de representation mecanique de la formation des fractures naturelles d'un reservoir petrolier

Energy Technology Data Exchange (ETDEWEB)

Picard, D.

2005-09-15

The optimisation of the oil production requires a better characterisation of naturally fractured reservoirs. We consider and analyse two spatial distributions. One with systematic joints is arranged in an homogeneous way; joint spacing is linked to individual bedding thickness with propagation frequently interrupted by stratigraphic interfaces (single layer jointing). The second, so-called fracture swarms, consists in fractures clustering, where stratigraphic interfaces seem to play a minor role. The analysis is based on the singularity theory and matched asymptotic expansions method with a fine scale for local perturbations and a global one for general trends. We examine the conditions of fracture propagation that are determined herein using simultaneously two fracture criteria an energy and a stress condition. We consider two modes of loading. Usually, the joint (crack opening mode) and fracture swarm growths are explained by a first order phenomenon involving effective traction orthogonal to fracture plane. Although commonly used, this hypothesis seems unrealistic in many circumstances and may conflict with geological observations. Then, we try to describe fracture growth as a second order phenomena resulting from crack parallel compression. As far as propagation across layer interfaces is concerned, the effect of loading and geometry has been summarised in maps of fracture mechanisms, describing areas of 'step-over', 'straight through propagation' and 'crack arrest'. Fracture criteria, relative size of heterogeneities, contrast of mechanical properties between bed and layer are parameters of the problem. For fracture swarms, we present a discussion bringing out what is reasonable as a loading to justify their morphology. In particular, horizontal effective tension is unable to explain neighbouring joints. Simultaneous propagation of parallel near cracks is explained by finite width cracks growing under the influence of vertical
Geological mapping of investigation trench OL-TK14 at the Olkiluoto study site, Eurajoki, SW Finland

International Nuclear Information System (INIS)

Nordbaeck, N.

2007-12-01

Geological mapping of investigation trench OL-TK14 was carried out by the Geological Survey of Finland at the Olkiluoto study site, Eurajoki, as part of Posiva Oy's site investigation programme for the development of an underground repository for nuclear waste. The E-W striking, ca. 215 m long trench is located in the eastern part of the Olkiluoto Island adjacent to boreholes OL-KR40 and OL-KR45. The trench was cleaned with a pressure washer and pressurized air. The rock types were determined macroscopically. Five samples were also investigated microscopically. The main rock type in the trench is veined gneiss. A few less than 0.5 m wide coarsegrained pegmatitic granite dykes are also encountered. Furthermore a large number of mica gneiss, quartz gneiss and skarn inclusions are present in the veined gneiss, being often elongated and parallel to the foliation. The most dominant tectonic feature is the foliation S2 and associated intense granitic leucosome veining. The foliation strikes ENE-WSW and dips steeply towards SES. Intensely to moderately banded rocks dominate the trench. The sparse F3 folds observed in OL-TK14 are small-scale tight folds in leucosome veins. A large-scale (10 m) open bending of the foliation that could be a result of D4 folding was also observed. Shearbands and other signs of ductile shearing were observed on many locations in the trench and in the eastern part there is a high-grade ductile shear zone intersection. During the fracture mapping, all fractures intersecting the central thread were investigated and a total of 684 fractures were recorded. The average fracture density of the trench is 3.18 fractures/m. On the basis of fracture orientations three main sets can be distinguished: 1) a set striking N-S with vertical dip, 2) a ENE-WSW striking set with varying dips towards the SSE (parallel to the foliation) and 3) a NE-SW striking set with sub-vertical dip towards the SE or the NW. Most of the measured fractures are short due to the

Structural-Diagenetic Controls on Fracture Opening in Tight Gas Sandstone Reservoirs, Alberta Foothills

Science.gov (United States)

Ukar, Estibalitz; Eichhubl, Peter; Fall, Andras; Hooker, John

2013-04-01

In tight gas reservoirs, understanding the characteristics, orientation and distribution of natural open fractures, and how these relate to the structural and stratigraphic setting are important for exploration and production. Outcrops provide the opportunity to sample fracture characteristics that would otherwise be unknown due to the limitations of sampling by cores and well logs. However, fractures in exhumed outcrops may not be representative of fractures in the reservoir because of differences in burial and exhumation history. Appropriate outcrop analogs of producing reservoirs with comparable geologic history, structural setting, fracture networks, and diagenetic attributes are desirable but rare. The Jurassic to Lower Cretaceous Nikanassin Formation from the Alberta Foothills produces gas at commercial rates where it contains a network of open fractures. Fractures from outcrops have the same diagenetic attributes as those observed in cores fractures relative to fold cores, hinges and limbs, 2) compare the distribution and attributes of fractures in outcrop vs. core samples, 3) estimate the timing of fracture formation relative to the evolution of the fold-and-thrust belt, and 4) estimate the degradation of fracture porosity due to postkinematic cementation. Cathodoluminescence images of cemented fractures in both outcrop and core samples reveal several generations of quartz and ankerite cement that is synkinematic and postkinematic relative to fracture opening. Crack-seal textures in synkinematic quartz are ubiquitous, and well-developed cement bridges abundant. Fracture porosity may be preserved in fractures wider than ~100 microns. 1-D scanlines in outcrop and core samples indicate fractures are most abundant within small parasitic folds within larger, tight, mesoscopic folds. Fracture intensity is lower away from parasitic folds; intensity progressively decreases from the faulted cores of mesoscopic folds to their forelimbs, with lowest intensities within
Bimalleolar ankle fracture with proximal fibular fracture

NARCIS (Netherlands)

Colenbrander, R. J.; Struijs, P. A. A.; Ultee, J. M.

2005-01-01

A 56-year-old female patient suffered a bimalleolar ankle fracture with an additional proximal fibular fracture. This is an unusual fracture type, seldom reported in literature. It was operatively treated by open reduction and internal fixation of the lateral malleolar fracture. The proximal fibular
Spatial Pattern of Groundwater Arsenic Occurrence and Association with Bedrock Geology in Greater Augusta, Maine, USA

Science.gov (United States)

Yang, Qiang; Jung, Hun Bok; Culbertson, Charles W.; Marvinney, Robert G.; Loiselle, Marc C.; Locke, Daniel B.; Cheek, Heidi; Thibodeau, Hilary; Zheng, Yan

2009-01-01

In New England, groundwater arsenic occurrence has been linked to bedrock geology on regional scales. To ascertain and quantify this linkage at intermediate (100-101 km) scales, 790 groundwater samples from fractured bedrock aquifers in the greater Augusta, Maine area are analyzed. 31% of the sampled wells have arsenic >10 μg/L. The probability of [As] exceeding 10 μg/L mapped by indicator kriging is highest in Silurian pelite-sandstone and pelite-limestone units (~40%). This probability differs significantly (pbedrock map. Thus, bedrock geology is associated with arsenic occurrence in fractured bedrock aquifers of the study area at intermediate scales relevant to water resources planning. The arsenic exceedance rate for each rock unit is considered robust because low, medium and high arsenic occurrences in 4 cluster areas (3-20 km2) with a low sampling density of 1-6 wells per km2 are comparable to those with a greater density of 5-42 wells per km2. About 12,000 people (21% of the population) in the greater Augusta area (~1135 km2) are at risk of exposure to >10 μg/L arsenic in groundwater. PMID:19475939
An analysis of fracture trace patterns in areas of flat-lying sedimentary rocks for the detection of buried geologic structure. [Kansas and Texas

Science.gov (United States)

Podwysocki, M. H.

1974-01-01

Two study areas in a cratonic platform underlain by flat-lying sedimentary rocks were analyzed to determine if a quantitative relationship exists between fracture trace patterns and their frequency distributions and subsurface structural closures which might contain petroleum. Fracture trace lengths and frequency (number of fracture traces per unit area) were analyzed by trend surface analysis and length frequency distributions also were compared to a standard Gaussian distribution. Composite rose diagrams of fracture traces were analyzed using a multivariate analysis method which grouped or clustered the rose diagrams and their respective areas on the basis of the behavior of the rays of the rose diagram. Analysis indicates that the lengths of fracture traces are log-normally distributed according to the mapping technique used. Fracture trace frequency appeared higher on the flanks of active structures and lower around passive reef structures. Fracture trace log-mean lengths were shorter over several types of structures, perhaps due to increased fracturing and subsequent erosion. Analysis of rose diagrams using a multivariate technique indicated lithology as the primary control for the lower grouping levels. Groupings at higher levels indicated that areas overlying active structures may be isolated from their neighbors by this technique while passive structures showed no differences which could be isolated.
Correlation of Hip Fracture with Other Fracture Types: Toward a Rational Composite Hip Fracture Endpoint

Science.gov (United States)

Colón-Emeric, Cathleen; Pieper, Carl F.; Grubber, Janet; Van Scoyoc, Lynn; Schnell, Merritt L; Van Houtven, Courtney Harold; Pearson, Megan; Lafleur, Joanne; Lyles, Kenneth W.; Adler, Robert A.

2016-01-01

Purpose With ethical requirements to the enrollment of lower risk subjects, osteoporosis trials are underpowered to detect reduction in hip fractures. Different skeletal sites have different levels of fracture risk and response to treatment. We sought to identify fracture sites which cluster with hip fracture at higher than expected frequency; if these sites respond to treatment similarly, then a composite fracture endpoint could provide a better estimate of hip fracture reduction. Methods Cohort study using Veterans Affairs and Medicare administrative data. Male Veterans (n=5,036,536) aged 50-99 years receiving VA primary care between1999-2009 were included. Fractures were ascertained using ICD9 and CPT codes and classified by skeletal site. Pearson correlation coefficients, logistic regression and kappa statistics, were used to describe the correlation between each fracture type and hip fracture within individuals, without regards to the timing of the events. Results 595,579 (11.8%) men suffered 1 or more fractures and 179,597 (3.6%) suffered 2 or more fractures during the time under study. Of those with one or more fractures, rib was the most common site (29%), followed by spine (22%), hip (21%) and femur (20%). The fracture types most highly correlated with hip fracture were pelvic/acetabular (Pearson correlation coefficient 0.25, p<0.0001), femur (0.15, p<0.0001), and shoulder (0.11, p<0.0001). Conclusions Pelvic, acetabular, femur, and shoulder fractures cluster with hip fractures within individuals at greater than expected frequency. If we observe similar treatment risk reductions within that cluster, subsequent trials could consider use of a composite endpoint to better estimate hip fracture risk. PMID:26151123
Status Report on the Geology of the Oak Ridge Reservation

Energy Technology Data Exchange (ETDEWEB)

Hatcher, R.D., Jr.

1992-01-01

This report provides an introduction to the present state of knowledge of the geology of the Oak Ridge Reservation (ORR) and a cursory introduction to the hydrogeology. A detailed reported on hydrogeology is being produced in parallel to this one. An important element of this work is the construction of a modern detailed geologic map of the ORR containing subdivisions of all mappable rock units and displaying mesoscopic structural data. Understanding the geologic framework of the ORR is essential to many current and proposed activities related to land-use planning, waste management, environmental restoration, and waste remediation. This interim report is the result of cooperation between geologists in two Oak Ridge National Laboratory (ORNL) divisions, Environmental Sciences and Energy, and is a major part of one doctoral dissertation in the Department of Geological Sciences at The University of Tennessee--Knoxville. Major long-term goals of geologic investigations in the ORR are to determine what interrelationships exist between fractures systems in individual rock or tectonic units and the fluid flow regimes, to understand how regional and local geology can be used to help predict groundwater movement, and to formulate a structural-hydrologic model that for the first time would enable prediction of the movement of groundwater and other subsurface fluids in the ORR. Understanding the stratigraphic and structural framework and how it controls fluid flow at depth should be the first step in developing a model for groundwater movement. Development of a state-of-the-art geologic and geophysical framework for the ORR is therefore essential for formulating an integrated structural-hydrologic model. This report is also intended to convey the present state of knowledge of the geologic and geohydrologic framework of the ORR and vicinity and to present some of the data that establish the need for additional geologic mapping and geohydrologic studies. An additional intended
Bedrock geologic map of the Nashua South quadrangle, Hillsborough County, New Hampshire, and Middlesex County, Massachusetts

Science.gov (United States)

Walsh, Gregory J.; Jahns, Richard H.; Aleinikoff, John N.

2013-01-01

The bedrock geology of the 7.5-minute Nashua South quadrangle consists primarily of deformed Silurian metasedimentary rocks of the Berwick Formation. The metasedimentary rocks are intruded by a Late Silurian to Early Devonian diorite-gabbro suite, Devonian rocks of the Ayer Granodiorite, Devonian granitic rocks of the New Hampshire Plutonic Suite including pegmatite and the Chelmsford Granite, and Jurassic diabase dikes. The bedrock geology was mapped to study the tectonic history of the area and to provide a framework for ongoing hydrogeologic characterization of the fractured bedrock of Massachusetts and New Hampshire. This report presents mapping by G.J. Walsh and R.H. Jahns and zircon U-Pb geochronology by J.N. Aleinikoff. The complete report consists of a map, text pamphlet, and GIS database. The map and text pamphlet are only available as downloadable files (see frame at right). The GIS database is available for download in ESRITM shapefile and Google EarthTM formats, and includes contacts of bedrock geologic units, faults, outcrops, structural geologic information, photographs, and a three-dimensional model.
Geologic map of the Montoso Peak quadrangle, Santa Fe and Sandoval Counties, New Mexico

Science.gov (United States)

Thompson, Ren A.; Hudson, Mark R.; Shroba, Ralph R.; Minor, Scott A.; Sawyer, David A.

2011-01-01

The Montoso Peak quadrangle is underlain by volcanic rocks and associated sediments of the Cerros del Rio volcanic field in the southern part of the Española Basin that record volcanic, faulting, alluvial, colluvial, and eolian processes over the past three million years. The geology was mapped from 1997 to 1999 and modified in 2004 to 2008. The geologic mapping was carried out in support of the U.S. Geological Survey (USGS) Rio Grande Basin Project, funded by the USGS National Cooperative Geologic mapping Program. The mapped distribution of units is based primarily on interpretation of 1:16,000-scale, color aerial photographs taken in 1992, and 1:40,000-scale, black-and-white, aerial photographs taken in 1996. Most of the contacts on the map were transferred from the aerial photographs using a photogrammetric stereoplotter and subsequently field checked for accuracy and revised based on field determination of allostratigraphic and lithostratigraphic units. Determination of lithostratigraphic units in volcanic deposits was aided by geochemical data, 40Ar/39Ar geochronology, aeromagnetic and paleomagnetic data. Supplemental revision of mapped contacts was based on interpretation of USGS 1-meter orthoimagery. This version of the Montoso Peak quadrangle geologic map uses a traditional USGS topographic base overlain on a shaded relief base generated from 10-m digital elevation model (DEM) data from the USGS National Elevation Dataset (NED). Faults are identified with varying confidence levels in the map area. Recognizing and mapping faults developed near the surface in young, brittle volcanic rocks is difficult because (1) they tend to form fractured zones tens of meters wide rather than discrete fault planes, (2) the youth of the deposits has allowed only modest displacements to accumulate for most faults, and (3) many may have significant strike-slip components that do not result in large vertical offsets that are readily apparent in offset of sub
ROCK FRACTURES NEAR FAULTS: SPECIFIC FEATURES OF STRUCTURAL‐PARAGENETIC ANALYSIS

Directory of Open Access Journals (Sweden)

Yu. P. Burzunova

2017-01-01

Full Text Available The new approach to structural‐paragenetic analysis of near‐fault fractures [Seminsky, 2014, 2015] and specific features of its application are discussed. This approach was tested in studies of fracturing in West Pribaikalie and Central Mongolia. We give some recommendations concerning collection, selection and initial processing of the data on fractures and faults. The analysis technique is briefly described, and its distinctive details are specified. Under the new approach, we compare systems of natural fractures with the standard joint sets. By analysing the mass measurements of the orientations of joint sets in a fault zone, it becomes possible to reveal the characteristics of this fault zone, such as its structure, morphogenetic type, etc. The comparative analysis is based on the identification of the main fracture paragenesis near the faults. This paragenesis is represented by a triplet of mutually perpendicular joint sets. The technique uses the qualitative approach to establish the rank hierarchy of fractures and stress fields on the basis of genetic subordination. We collect and analyse the data on tectonic fractures identified from a number of indicators, the main of which are the geometric structure of the (systematic or chaotic fracture system, and shear type of fractures. The new technique can be applied to analyse other genetic types of fractures (primary, hypergenic, provided that tectonic stresses were significantly involved in fracturing, which is evidenced by the corresponding indicators. Methods for conducting geological and structural observations are uniform for all sites and points, and increasing the number of observation points provides for a more effective use of the new technique. In our paper, we give specific parameters for constructing circle fracture diagrams. All the maximums in the diagram are involved in the analysis for comparison with the standard patterns. Errors caused by random coincidence are minimized
A new impulse-stage sand fracturing technology and its pilot application in the western Sichuan Basin

Directory of Open Access Journals (Sweden)

Bin Qi

2015-03-01

Full Text Available A better placement of proppants has been always the goal pursued in sand fracturing in order to get longer effective fractures and higher flow conductivity. However, it is always difficult to achieve satisfactory effects by conventional processes. On the basis of theoretical analysis and simulation with FracproPT software, basic experiments, and innovative physical modeling experiment, a new impulse-stage fracturing process has been developed by combining a special pumping process with fiber, liquid and other auxiliary engineering means. Compared with conventional fracturing, the open seepage channel created by the new fracturing process has an obvious edge in effective fracture length and flow conductivity. Moreover, the open seepage channel can also improve fracture cleanliness and reduce pressure loss in artificial fractures, thus reaching the goal of prolonging the single-well production time and maximizing productivity. After the research on principles and optimal design of this new process, on-site pilot test and detailed post-fracturing evaluation were conducted. The results indicated that (1 the new process is highly operable and feasible; (2 compared with the adjacent wells with similar geological conditions, the proppant' cost is reduced by 44%–47%, the ratio of effective fracture length to propped fracture length is increased by about 16%, the fracturing fluid recovery rate is up to 63% after 18 h in the test, and the normalized production is 1.9–2.3 times that of the adjacent wells; and (3 the new process can significantly lower the cost and enhance production. The process has a broad application prospect in shallow-middle sand gas reservoirs and shale gas reservoirs in western Sichuan Basin.
Foal Fractures: Osteochondral Fragmentation, Proximal Sesamoid Bone Fractures/Sesamoiditis, and Distal Phalanx Fractures.

Science.gov (United States)

Reesink, Heidi L

2017-08-01

Foals are susceptible to many of the same types of fractures as adult horses, often secondary to external sources of trauma. In addition, some types of fractures are specific to foals and occur routinely in horses under 1 year of age. These foal-specific fractures may be due to the unique musculoskeletal properties of the developing animal and may present with distinct clinical signs. Treatment plans and prognoses are tailored specifically to young animals. Common fractures not affecting the long bones in foals are discussed in this article, including osteochondral fragmentation, proximal sesamoid bone fractures/sesamoiditis, and distal phalanx fractures. Copyright © 2017 Elsevier Inc. All rights reserved.
Installation of borehole seismometer for earthquake characteristics in deep geological environment

Energy Technology Data Exchange (ETDEWEB)

Park, Dong Hee; Choi, Weon Hack; Cho, Sung Il; Chang, Chun Joong [KHNP CRI, Seoul (Korea, Republic of)

2014-10-15

Deep geological disposal is currently accepted as the most appropriate method for permanently removing spent nuclear fuel from the living sphere of humans. For implementation of deep geological disposal, we need to understand the geological changes that have taken place over the past 100,000 years, encompassing active faults, volcanic activity, elevation, ubsidence, which as yet have not been considered in assessing the site characteristics for general facilities, as well as to investigate and analyze the geological structures, fracture systems and seismic responses regarding deep geological environment about 500 meters or more underground. In regions with high seismic activity, such as Japan, the Western United States and Taiwan, borehole seismometers installed deep underground are used to monitor seismic activity during the course of seismic wave propagation at various depths and to study the stress changes due to earthquakes and analyze the connection to fault movements. Korea Hydro and Nuclear Power Co., Ltd. (KHNP) have installed the deep borehole earthquake observatory at depths of about 300 to 600 meters in order to study the seismic response characteristics in deep geological environment on June, 2014 in Andong area. This paper will show the status of deep borehole earthquake observatory and the results of background noise response characteristics of these deep borehole seismic data as a basic data analysis. We present here the status of deep borehole seismometer installation by KHNP. In order to basic data analysis for the borehole seismic observation data, this study shows the results of the orientation of seismometer and background noise characteristics by using a probability density function. Together with the ground motion data recorded by the borehole seismometers can be utilized as basic data for seismic response characteristics studies with regard to spent nuclear fuel disposal depth and as the input data for seismic hazard assessment that
Analysis of geological condition and prospecting potential of uranium metallogenesis in Maling granite mass

International Nuclear Information System (INIS)

Shao Fei; Zou Maoqing; Wu Yong; Xu Jinshan; Xu Wang; Chen Chang

2011-01-01

Based on the study of regional geological evolution of Maling granite mass, uranium content of granite mass and its peripheric strata, petrogeochemistry and the known spatial distribution pattern of uranium mineralization and ore-controlling structures, new recognition is 1) Maling composite mass is the 'S' type re-melted granite, 2) the accumulative area of regional uranium metallogenic substances forms uranium-rich re-melted strata, 3) magma evolution is the matter base for the uranium-rich hydrotherm, 4) NE-trending main faults are channels for metallogenesis and the lateral high-angle dipping faults, fractures and interlayer fractures in the peripheric strata are the spaces of mineralization. The ore intersected by drilling in Maling granite is acidic type. Prospecting potential of Maling granite mass is analyzed, and preferable prospecting space is delineated for further exploration. (authors)
Mechanical Integrity of Canisters Using a Fracture Mechanics Approach

Energy Technology Data Exchange (ETDEWEB)

Koyama, Tomofumi; Guoxiang Zhang; Lanru Jing [Royal Inst. of Technology, Stockholm (Sweden). Dept. of Land and Water Resources Engineering

2006-07-15

This report presents the methods and results of a research project about numerical modeling of mechanical integrity of cast-iron canisters for the final disposal of spent nuclear fuel in Sweden, using combined boundary element (BEM) and finite element (FEM) methods. The objectives of the project are: 1) to investigate the possibility of initiation and growth of fractures in the cast-iron canisters under the mechanical loading conditions defined in the premises of canister design by Swedish Nuclear Fuel and Waste Management Co. (SKB); 2) to investigate the maximum bearing capacity of the cast iron canisters under uniformly distributed and gradually increasing boundary pressure until plastic failure. Achievement of the two objectives may provide some quantitative evidence for the mechanical integrity and overall safety of the cast-iron canisters that are needed for the final safety assessment of the geological repository of the radioactive waste repository in Sweden. The geometrical dimension, distribution and magnitudes of loads and Material properties of the canisters and possible fractures were provided by the latest investigations of SKB. The results of the BEM simulations, using the commercial code BEASY, indicate that under the currently defined loading conditions the possibility of initiation of new fractures or growth of existing fractures (defects) are very small, due to the reasons that: 1) the canisters are under mainly compressive stresses; 2) the induced tensile stress regions are too small in both dimension and magnitude to create new fractures or to induce growth of existing fractures, besides the fact that the toughness of the fractures in the cast iron canisters are much higher that the stress intensity factors in the fracture tips. The results of the FEM simulation show a approximately 75 MPa maximum pressure beyond which plastic collapse of the cast-iron canisters may occur, using an elastoplastic Material model. This figure is smaller compared
Effect of Chemical Reactions on the Hydrologic Properties of Fractured and Rubbelized Glass Media

International Nuclear Information System (INIS)

Saripalli, Prasad; Meyer, P D.; Parker, Kent E.; Lindberg, Michael J.

2005-01-01

Understanding the effect of chemical reactions on the hydrologic properties of geological media, such as porosity, permeability and dispersivity, is critical to many natural and engineered sub-surface systems. Influence of glass corrosion (precipitation and dissolution) reactions on fractured and rubbelized (crushed) forms HAN28 and LAWBP1, two candidate waste glass forms for a proposed immobilized low-activity waste (ILAW) disposal facility at the Hanford, WA site, was investigated. Flow and tracer transport experiments were conducted using fractured and rubbelized forms, before and after subjecting them to corrosion using Vapor Hydration Testing (VHT) at 200 C temperature and 200 psig pressure, causing the precipitation of alteration products. Data were analyzed using analytical expressions and CXTFIT, a transport parameter optimization code, for the estimation of the hydrologic characteristics before and after VHT. It was found that glass reactions significantly influence the hydrologic properties of ILAW glass media. Hydrologic properties of rubbelized glass decreased due to precipitation reactions, whereas those of fractured glass media increased due to reaction which led to unconfined expansion of fracture aperture. The results are unique and useful to better understand the effect of chemical reactions on the hydrologic properties of fractured and rubbelized stony media in general and glass media in particular
Acetabular Fracture

Directory of Open Access Journals (Sweden)

Chad Correa

2017-09-01

Full Text Available History of present illness: A 77-year-old female presented to her primary care physician (PCP with right hip pain after a mechanical fall. She did not lose consciousness or have any other traumatic injuries. She was unable to ambulate post-fall, so X-rays were ordered by her PCP. Her X-rays were concerning for a right acetabular fracture (see purple arrows, so the patient was referred to the emergency department where a computed tomography (CT scan was ordered. Significant findings: The non-contrast CT images show a minimally displaced comminuted fracture of the right acetabulum involving the acetabular roof, medial and anterior walls (red arrows, with associated obturator muscle hematoma (blue oval. Discussion: Acetabular fractures are quite rare. There are 37 pelvic fractures per 100,000 people in the United States annually, and only 10% of these involve the acetabulum. They occur more frequently in the elderly totaling an estimated 4,000 per year. High-energy trauma is the primary cause of acetabular fractures in younger individuals and these fractures are commonly associated with other fractures and pelvic ring disruptions. Fractures secondary to moderate or minimal trauma are increasingly of concern in patients of advanced age.1 Classification of acetabular fractures can be challenging. However, the approach can be simplified by remembering the three basic types of acetabular fractures (column, transverse, and wall and their corresponding radiologic views. First, column fractures should be evaluated with coronally oriented CT images. This type of fracture demonstrates a coronal fracture line running caudad to craniad, essentially breaking the acetabulum into two halves: a front half and a back half. Secondly, transverse fractures should be evaluated by sagittally oriented CT images. By definition, a transverse fracture separates the acetabulum into superior and inferior halves with the fracture line extending from anterior to posterior
Technetium behaviour under deep geological conditions

International Nuclear Information System (INIS)

Kumata, M.; Vandergraaf, T.T.

1993-01-01

The migration behaviour of technetium under deep geological conditions was investigated by performing column tests using groundwater and altered granitic rock sampled from a fracture zone in a granitic pluton at a depth of about 250 m. The experiment was performed under a pressure of about 0.7 MPa in a controlled atmosphere glove box at the 240 m level of the Underground Research Laboratory (URL) near Pinawa, Manitoba, Canada. The technetium was strongly sorbed on the dark mafic minerals in the column. With the exception of a very small unretarded fraction that was eluted with the tritiated water, no further breakthrough of technetium was observed. This strong sorption of technetium on the mineral surface was caused by reduction of Tc(VII), probably to Tc(IV) even though the groundwater was only mildly reducing. (author) 5 figs., 4 tabs., 15 refs
INTEGRATION OF PALSAR AND ASTER SATELLITE DATA FOR GEOLOGICAL MAPPING IN TROPICS

Directory of Open Access Journals (Sweden)

A. Beiranvand Pour

2015-10-01

Full Text Available This research investigates the integration of the Phased Array type L-band Synthetic Aperture Radar (PALSAR and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER satellite data for geological mapping applications in tropical environments. The eastern part of the central belt of peninsular Malaysia has been investigated to identify structural features and mineral mapping using PALSAR and ASTER data. Adaptive local sigma and directional filters were applied to PALSAR data for detecting geological structure elements in the study area. The vegetation, mineralogic and lithologic indices for ASTER bands were tested in tropical climate. Lineaments (fault and fractures and curvilinear (anticline or syncline were detected using PALSAR fused image of directional filters (N-S, NE-SW, and NW-SE.Vegetation index image map show vegetation cover by fusing ASTER VNIR bands. High concentration of clay minerals zone was detected using fused image map derived from ASTER SWIR bands. Fusion of ASTER TIR bands produced image map of the lithological units. Results indicate that data integration and data fusion from PALSAR and ASTER sources enhanced information extraction for geological mapping in tropical environments.
Fractures inside crystalline rocks. Effects of deformations on fluid circulations; Fractures dans les roches cristallines. Effets des deformations sur les circulations de fluides

Energy Technology Data Exchange (ETDEWEB)

Gentier, S

2005-07-01

The modeling of fluid flows inside granite massifs is an important task for the evaluation of the feasibility of radioactive waste storage inside such formations. This document makes a synthesis of the works carried out since about 15 years, in particular by the French bureau of geological and mining research (BRGM), about the hydro-mechanical behaviour of a fracture and about the hydrodynamical characterization of fracture networks inside crystalline rocks: 1 - introduction; 2 - hydro-mechanical behaviour under normal stress: experimental results (hydro-mechanical behaviour, flow regimes, mechanical behaviour, test protocol, complementary tests, influence of samples size), geometrical interpretation of experimental results (relation with walls geometry, relation with voids geometry, relation with contacts geometry), hydro-mechanical modeling (hydraulic modeling, mechanical modeling); 3 - from the hydro-mechanical behaviour under normal stress to the coupling with heat transfers and chemistry: experiment for the study of the chemo-thermo-hydro-mechanical coupling (experimental results, relation with walls morphology), thermo-hydro-mechanical experiments, thermo-hydro-chemical experiments with fractures, conclusions; 4 - hydro-mechanical behaviour during shear: experimental results, geometrical interpretation (relation with the geometry of damaged zones, relation with voids geometry, relation with walls geometry), hydro-mechanical modeling (mechanical modeling, hydro-mechanical modeling of the behaviour during shear). (J.S.)
Geologic isolation programs in other countries

International Nuclear Information System (INIS)

Gera, F.

1976-01-01

Several nations other than West Germany and The Netherlands have declared their intention to investigate geological formations as potential radioactive waste repositories. In Belgium, the formations underlying the Mol Center have been cored down to about 570 m. The target formation is a bed of tertiary clay 165 to 265 m below the surface. The plan is to produce a 10,000-m 3 cavity in the middle of this clay and to use it for the disposal of intermediate-level and alpha-bearing wastes. France has a program underway to assess salt and crystalline formations as possible waste-disposal sites. In Italy, the feasibility of high-level-waste disposal in clay formations is being explored. In situ experiments will be performed in the massive clays underlying the Trisaia Center in southern Italy. Spain has begun studies on waste disposal in salt, clay, anhydrite, and crystalline formations. In Sweden, attention is focused on the possibility of disposal in Precambrian crystalline bedrock. In Switzerland, where crystalline rocks are always fractured, large formations of salt are not known, and suitable clay or marl formations have not been identified, anhydrite formations are being studied. The United Kingdom has declared its intention to investigate clays and crystalline rocks. Other countries that have revealed plans to assess geologic disposal within their territories include Austria, Denmark, India, the German Democratic Republic, and the Soviet Union

Acoustic Monitoring of Gravity-Driven Controls on CaCO3 Precipitates in a Fracture

Science.gov (United States)

Xu, Z.; Sheets, J.; Zhang, L.; Kim, D.; Kneafsey, T. J.; Cole, D. R.; Jun, Y. S.; Pyrak-Nolte, L. J.

2017-12-01

the orientation thus affecting the ability of a fracture to self-heal if oriented vertically. This work was supported by the Center for Nanoscale Controls on Geologic CO (NCGC), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-AC02-05CH11231
Radionuclide transport in fractured rock: quantifying releases from final disposal of high level waste

International Nuclear Information System (INIS)

Silveira, Claudia S. da; Alvim, Antonio C.M.

2013-01-01

Crystalline rock has been considered as a potentially suitable matrix for high-level radioactive waste (HLW) repository because it is found in very stable geological formations and may have very low permeability. In this study the adopted physical system consists of the rock matrix containing a discrete horizontal fracture in a water saturated porous rock and a system of vertical fractures as a lineament. The transport in the fractures - horizontal and vertical, is assumed to obey a relation convection-diffusion, while the molecular diffusion is considered dominant mechanism of transport in porous rock. In this model the decay chain is considered. We use a code in Fortran 90, where the partial differential equations that describe the movement of radionuclides were discretized by finite differences methods. We use the fully implicit method for temporal discretization schemes. The simulation was performed with relevant data of nuclides in spent fuel for performance assessment in a hypothetical repository, thus quantifying the radionuclides released into the host rock. (author)
The role of local stress perturbation on the simultaneous opening of orthogonal fractures

Science.gov (United States)

Boersma, Quinten; Hardebol, Nico; Barnhoorn, Auke; Bertotti, Giovanni; Drury, Martyn

2016-04-01

Orthogonal fracture networks (ladder-like networks) are arrangements that are commonly observed in outcrop studies. They form a particularly dense and well connected network which can play an important role in the effective permeability of tight hydrocarbon or geothermal reservoirs. One issue is the extent to which both the long systematic and smaller cross fractures can be simultaneously critically stressed under a given stress condition. Fractures in an orthogonal network form by opening mode-I displacements in which the main component is separation of the two fracture walls. This opening is driven by effective tensile stresses as the smallest principle stress acting perpendicular to the fracture wall, which accords with linear elastic fracture mechanics. What has been well recognized in previous field and modelling studies is how both the systematic fractures and perpendicular cross fractures require the minimum principle stress to act perpendicular to the fracture wall. Thus, these networks either require a rotation of the regional stress field or local perturbations in stress field. Using a mechanical finite element modelling software, a geological case of layer perpendicular systematic mode I opening fractures is generated. New in our study is that we not only address tensile stresses at the boundary, but also address models using pore fluid pressure. The local stress in between systematic fractures is then assessed in order to derive the probability and orientation of micro crack propagation using the theory of sub critical crack growth and Griffith's theory. Under effective tensile conditions, the results indicate that in between critically spaced systematic fractures, local effective tensile stresses flip. Therefore the orientation of the least principle stress will rotate 90°, hence an orthogonal fracture is more likely to form. Our new findings for models with pore fluid pressures instead of boundary tension show that the magnitude of effective tension
Influence of Chemical, Mechanical, and Transport Processes on Wellbore Leakage from Geologic CO2 Storage Reservoirs.

Science.gov (United States)

Carroll, Susan A; Iyer, Jaisree; Walsh, Stuart D C

2017-08-15

Wells are considered to be high-risk pathways for fluid leakage from geologic CO 2 storage reservoirs, because breaches in this engineered system have the potential to connect the reservoir to groundwater resources and the atmosphere. Given these concerns, a few studies have assessed leakage risk by evaluating regulatory records, often self-reported, documenting leakage in gas fields. Leakage is thought to be governed largely by initial well-construction quality and the method of well abandonment. The geologic carbon storage community has raised further concerns because acidic fluids in the CO 2 storage reservoir, alkaline cement meant to isolate the reservoir fluids from the overlying strata, and steel casings in wells are inherently reactive systems. This is of particular concern for storage of CO 2 in depleted oil and gas reservoirs with numerous legacy wells engineered to variable standards. Research suggests that leakage risks are not as great as initially perceived because chemical and mechanical alteration of cement has the capacity to seal damaged zones. Our work centers on defining the coupled chemical and mechanical processes governing flow in damaged zones in wells. We have developed process-based models, constrained by experiments, to better understand and forecast leakage risk. Leakage pathways can be sealed by precipitation of carbonate minerals in the fractures and deformation of the reacted cement. High reactivity of cement hydroxides releases excess calcium that can precipitate as carbonate solids in the fracture network under low brine flow rates. If the flow is fast, then the brine remains undersaturated with respect to the solubility of calcium carbonate minerals, and zones depleted in calcium hydroxides, enriched in calcium carbonate precipitates, and made of amorphous silicates leached of original cement minerals are formed. Under confining pressure, the reacted cement is compressed, which reduces permeability and lowers leakage risks. The
Associations of early premenopausal fractures with subsequent fractures vary by sites and mechanisms of fractures.

Science.gov (United States)

Honkanen, R; Tuppurainen, M; Kroger, H; Alhava, E; Puntila, E

1997-04-01

In a retrospective population-based study we assessed whether and how self-reported former fractures sustained at the ages of 20-34 are associated with subsequent fractures sustained at the ages of 35-57. The 12,162 women who responded to fracture questions of the baseline postal enquiry (in 1989) of the Kuopio Osteoporosis Study, Finland formed the study population. They reported 589 former and 2092 subsequent fractures. The hazard ratio (HR), with 95% confidence interval (CI), of a subsequent fracture was 1.9 (1.6-2.3) in women with the history of a former fracture compared with women without such a history. A former low-energy wrist fracture was related to subsequent low-energy wrist [HR = 3.7 (2.0-6.8)] and high-energy nonwrist [HR = 2.4 (1.3-4.4)] fractures, whereas former high-energy nonwrist fractures were related only to subsequent high-energy nonwrist [HR = 2.8 (1.9-4.1)] but not to low-energy wrist [HR = 0.7 (0.3-1.8)] fractures. The analysis of bone mineral density (BMD) data of a subsample of premenopausal women who underwent dual x-ray absorptiometry (DXA) during 1989-91 revealed that those with a wrist fracture due to a fall on the same level at the age of 20-34 recorded 6.5% lower spinal (P = 0.140) and 10.5% lower femoral (P = 0.026) BMD than nonfractured women, whereas the corresponding differences for women with a former nonwrist fracture due to high-energy trauma were -1.8% (P = 0.721) and -2.4% (P = 0. 616), respectively. Our results suggest that an early premenopausal, low-energy wrist fracture is an indicator of low peak BMD which predisposes to subsequent fractures in general, whereas early high-energy fractures are mainly indicators of other and more specific extraskeletal factors which mainly predispose to same types of subsequent fractures only.
Deep-reaching fracture zones in the crystalline basement surrounding the West Congo System and their control of mineralization in Angola and Gabon

NARCIS (Netherlands)

Boorder, H. de

1982-01-01

A framework of major, deep-reaching fracture zones in western Central Africa is inferred from airborne magnetometric and surface geological observations in Central Angola and Gabon. A correlation is proposed between these observations and the continental negative Bouguer anomaly. The minimum
California Geological Survey Geologic Map Index

Data.gov (United States)

California Natural Resource Agency — All the individual maps from the Geologic Atlas of California and the Regional Geologic map series have been georeferenced for display in a GIS (and viewable online...
Geological mapping of investigation trench OL-TK9 at the Olkiluoto study site, Eurajoki, SW Finland

International Nuclear Information System (INIS)

Nordbaeck, N.; Talikka, M.

2006-07-01

Geological mapping of trench OL-TK9 was carried out the by the Geological Survey of Finland at the Olkiluoto study site, Eurajoki, southwestern Finland, as a part of Posiva Oy's site investigation programme for the development of an underground repository for nuclear waste. The NW-SE striking trench, which is about 371 metres in length and 0.4-2.5 metres in width, is situated to the west from the OL-TK3 in the northwestern part of the study site. The rock types were determined macroscopically and the main rock types were further investigated microscopically. On the basis of the migmatite structure, the migmatitic gneisses at Olkiluoto can be divided into three groups: veined gneiss, stromatic gneiss and diatexitic gneiss. Most of the migmatitic gneisses in the trench are veined gneisses and only a few short sections of the diatexitic gneiss or K-feldspar porphyry exist. Stromatic gneisses were not encountered. The leucosome of the veined gneiss show vein like, more or less linear traces with some features similar to large-scale augen structures, whereas the migmatitic structure of the diatexitic gneiss is more asymmetric and irregular. The southernmost part of the trench is dominated by mica gneiss and pegmatitic granite. The mica gneiss is homogenous mica-rich rock that contains less than 10 % granite leucosome material. The pegmatitic granite shows variations in grain size, colour, and mode of occurrence. The veined gneiss dominates the central part of the trench. The northernmost part of the trench is mainly comprised of tonalitic-granodioritic-granitic gneiss, which has an igneous character. Most rocks in the trench are altered, the intensity of the alteration varies from weak to strong, and the most common alteration type is chloritisation. The intense alteration has resulted in pervasive softening and weathering of the bedrock in places and up to four meters thick layers of strongly weathered rocks were observed on the edges of the trench. The foliation S2B
Geology - Background complementary studies. Forsmark modelling stage 2.2

Energy Technology Data Exchange (ETDEWEB)

Stephens, Michael B. [Geological Survey of Sweden, Uppsala (Sweden); Skagius, Kristina [Kemakta Konsult AB, Stockholm (Sweden)] (eds.)

2007-09-15

During Forsmark model stage 2.2, seven complementary geophysical and geological studies were initiated by the geological modelling team, in direct connection with and as a background support to the deterministic modelling of deformation zones. One of these studies involved a field control on the character of two low magnetic lineaments with NNE and NE trends inside the target volume. The interpretation of these lineaments formed one of the late deliveries to SKB that took place after the data freeze for model stage 2.2 and during the initial stage of the modelling work. Six studies involved a revised processing and analysis of reflection seismic, refraction seismic and selected oriented borehole radar data, all of which had been presented earlier in connection with the site investigation programme. A prime aim of all these studies was to provide a better understanding of the geological significance of indirect geophysical data to the geological modelling team. Such essential interpretative work was lacking in the material acquired in connection with the site investigation programme. The results of these background complementary studies are published together in this report. The titles and authors of the seven background complementary studies are presented below. Summaries of the results of each study, with a focus on the implications for the geological modelling of deformation zones, are presented in the master geological report, SKB-R--07-45. The sections in the master report, where reference is made to each background complementary study and where the summaries are placed, are also provided. The individual reports are listed in the order that they are referred to in the master geological report and as they appear in this report. 1. Scan line fracture mapping and magnetic susceptibility measurements across two low magnetic lineaments with NNE and NE trend, Forsmark. Jesper Petersson, Ulf B. Andersson and Johan Berglund. 2. Integrated interpretation of surface and
Geology - Background complementary studies. Forsmark modelling stage 2.2

International Nuclear Information System (INIS)

Stephens, Michael B.; Skagius, Kristina

2007-09-01

During Forsmark model stage 2.2, seven complementary geophysical and geological studies were initiated by the geological modelling team, in direct connection with and as a background support to the deterministic modelling of deformation zones. One of these studies involved a field control on the character of two low magnetic lineaments with NNE and NE trends inside the target volume. The interpretation of these lineaments formed one of the late deliveries to SKB that took place after the data freeze for model stage 2.2 and during the initial stage of the modelling work. Six studies involved a revised processing and analysis of reflection seismic, refraction seismic and selected oriented borehole radar data, all of which had been presented earlier in connection with the site investigation programme. A prime aim of all these studies was to provide a better understanding of the geological significance of indirect geophysical data to the geological modelling team. Such essential interpretative work was lacking in the material acquired in connection with the site investigation programme. The results of these background complementary studies are published together in this report. The titles and authors of the seven background complementary studies are presented below. Summaries of the results of each study, with a focus on the implications for the geological modelling of deformation zones, are presented in the master geological report, SKB-R--07-45. The sections in the master report, where reference is made to each background complementary study and where the summaries are placed, are also provided. The individual reports are listed in the order that they are referred to in the master geological report and as they appear in this report. 1. Scan line fracture mapping and magnetic susceptibility measurements across two low magnetic lineaments with NNE and NE trend, Forsmark. Jesper Petersson, Ulf B. Andersson and Johan Berglund. 2. Integrated interpretation of surface and
Hydrogeological characterisation and modelling of deformation zones and fracture domains, Forsmark modelling stage 2.2

Energy Technology Data Exchange (ETDEWEB)

Follin, Sven (SF GeoLogic AB, Taeby (SE)); Leven, Jakob (Swedish Nuclear Fuel and Waste Management Co., Stockholm (SE)); Hartley, Lee; Jackson, Peter; Joyce, Steve; Roberts, David; Swift, Ben (Serco Assurance, Harwell (GB))

2007-09-15

The work reported here collates the structural-hydraulic information gathered in 21 cored boreholes and 32 percussion-drilled boreholes belonging to Forsmark site description, modelling stage 2.2. The analyses carried out provide the hydrogeological input descriptions of the bedrock in Forsmark needed by the end users Repository Engineering, Safety Assessment and Environmental Impact Assessment; that is, hydraulic properties of deformation zones and fracture domains. The same information is also needed for constructing 3D groundwater flow models of the Forsmark site and surrounding area. The analyses carried out render the following conceptual model regarding the observed heterogeneity in deformation zone transmissivity: We find the geological division of the deterministically modelled deformation zones into eight categories (sets) useful from a hydrogeological point of view. Seven of the eight categories are steeply dipping, WNW, NW, NNW, NNE, NE, ENE and EW, and on is gently dipping, G. All deformation zones, regardless of orientation (strike and dip), are subjected to a substantial decrease in transmissivity with depth. The data gathered suggest a contrast of c. 20,000 times for the uppermost one kilometre of bedrock, i.e. more than four orders of magnitude. The hydraulic properties below this depth are not investigated. The lateral heterogeneity is also substantial but more irregular in its appearance. For instance, for a given elevation and deformation zone category (orientation), the spatial variability in transmissivity within a particular deformation zone appears to be as large as the variability between all deformation zones. This suggests that the lateral correlation length is shorter than the shortest distance between two adjacent observation points and shorter than the category spacing. The observation that the mean transmissivity of the gently-dipping deformation zones is c. one to two orders of magnitude greater than the mean transmissivities of all
Dynamic simulations of geologic materials using combined FEM/DEM/SPH analysis

Energy Technology Data Exchange (ETDEWEB)

Morris, J P; Johnson, S M

2008-03-26

An overview of the Lawrence Discrete Element Code (LDEC) is presented, and results from a study investigating the effect of explosive and impact loading on geologic materials using the Livermore Distinct Element Code (LDEC) are detailed. LDEC was initially developed to simulate tunnels and other structures in jointed rock masses using large numbers of polyhedral blocks. Many geophysical applications, such as projectile penetration into rock, concrete targets, and boulder fields, require a combination of continuum and discrete methods in order to predict the formation and interaction of the fragments produced. In an effort to model this class of problems, LDEC now includes implementations of Cosserat point theory and cohesive elements. This approach directly simulates the transition from continuum to discontinuum behavior, thereby allowing for dynamic fracture within a combined finite element/discrete element framework. In addition, there are many application involving geologic materials where fluid-structure interaction is important. To facilitate solution of this class of problems a Smooth Particle Hydrodynamics (SPH) capability has been incorporated into LDEC to simulate fully coupled systems involving geologic materials and a saturating fluid. We will present results from a study of a broad range of geomechanical problems that exercise the various components of LDEC in isolation and in tandem.
Time scales for dissolution of calcite fracture fillings and implications for saturated zone radionuclide transport at Yucca Mountain, Nevada

International Nuclear Information System (INIS)

Winterle, J.R.; Murphy, W.M.

1999-01-01

An analysis was performed to estimate time scales for dissolution of calcite fracture fillings in the fractured tuff aquifer that underlies Yucca Mountain (YM), Nevada, where groundwater is chemically undersaturated with respect to calcite. The impetus for this analysis originates from speculation that undissolved calcite in the saturated zone is evidence for limited diffusive exchange between fracture and matrix waters. Assuming that matrix diffusion is the rate-limiting process, the time scale for dissolution of calcite fracture fillings depends on the amount of calcite initially deposited, the distance between flowing fractures, the degree of chemical disequilibrium, and the rate of diffusion. Assuming geochemistry of J-13 well water in free-flowing fractures, estimated time scales for complete dissolution of matrix-entrapped calcite range from about 10 4 yr for a 2 mm-thick deposit located 1 m from a flowing fracture, to over 10 7 yr for a 2 cm-thick deposit located 100 m from a flowing fracture. The authors conclude that, given the geochemical and hydrologic characteristics observed at YM, the persistence of calcite minerals over geologic time scales in aquifers where flowing water is under-saturated with calcite does not necessarily preclude matrix diffusion as a dilution mechanism. However, the model suggests that the effective spacing between flowing fractures may be large enough to diminish the overall benefit of matrix diffusion to proposed high-level waste repository performance
THE TECTONICS STRESS AND STRAIN FIELD MODELING ADJUSTED FOR EVOLUTION OF GEOLOGICAL STRUCTURES (SAILAG INTRUSION, EASTERN SAYAN

Directory of Open Access Journals (Sweden)

V. N. Voytenko

2013-01-01

Full Text Available The article describes a tectonophysical model showing evolution of structures in the Sailag granodiorite massif in relation to its gold-bearing capacity. The model takes into account the load patterns according to geological data, accumulated deformation, and gravity stresses. This model provides for updating the structural-geological model showing development of the intrusion body and the ore field. Forecasted are destruction patterns in the apical and above-dome parts of the massif in the intrusion and contraction phase, formation of the long-term shear zone at the steeply dipping slope of the intrusion body, and subvertical fractures associated with the long-term shear zone and vertical mechanical ‘layering’ of the intrusive body.
Geological characteristics of granite type uranium deposits in middle of Inner Mongolia in comparison with south China

International Nuclear Information System (INIS)

Wang Gui

2012-01-01

Granites extensively distributed in middle of Inner Mongolia and South China, namely Caledonian, Hercynian and Yanshanian. Some of the intrusive are composed of granites which belong to different ages. Some of the uranium deposits were found inside the granite bodies or in sedimentary rocks and meta sedimentary rocks along the exocontact zone. Granite rock was comparing in middle Inner Mongolia and South China, including Uranium ore-forming geological conditions. ore-forming process and Ore-controlling factors. Think the Uranium ore-forming geological conditions is similar; ore-forming process is mainly for low-mid temperature hot liquid; Uranium ore bodies (uranium mineralization) was controlled by fracture. Explain granite type uranium mineralization potential is tremendous in middle of Inner Mongolia. (author)
Semianalytical solutions of radioactive or reactive tracer transport in layered fractured media

International Nuclear Information System (INIS)

Moridis, G.J.; Bodvarsson, G.S.

2001-01-01

In this paper, semianalytical solutions are developed for the problem of transport of radioactive or reactive tracers (solutes or colloids) through a layered system of heterogeneous fractured media with misaligned fractures. The tracer transport equations in the matrix account for (a) diffusion, (b) surface diffusion (for solutes only), (c) mass transfer between the mobile and immobile water fractions, (d) linear kinetic or equilibrium physical, chemical, or combined solute sorption or colloid filtration, and (e) radioactive decay or first order chemical reactions. Any number of radioactive decay daughter products (or products of a linear, first-order reaction chain) can be tracked. The tracer-transport equations in the fractures account for the same processes, in addition to advection and hydrodynamic dispersion. Additionally, the colloid transport equations account for straining and velocity adjustments related to the colloidal size. The solutions, which are analytical in the Laplace space, are numerically inverted to provide the solution in time and can accommodate any number of fractured and/or porous layers. The solutions are verified using analytical solutions for limiting cases of solute and colloid transport through fractured and porous media. The effect of important parameters on the transport of 3 H, 237 Np and 239 Pu (and its daughters) is investigated in several test problems involving layered geological systems of varying complexity. 239 Pu colloid transport problems in multilayered systems indicate significant colloid accumulations at straining interfaces but much faster transport of the colloid than the corresponding strongly sorbing solute species
Solute transport in crystalline rocks at Aspö--I: geological basis and model calibration.

Science.gov (United States)

Mazurek, Martin; Jakob, Andreas; Bossart, Paul

2003-03-01

Water-conducting faults and fractures were studied in the granite-hosted Aspö Hard Rock Laboratory (SE Sweden). On a scale of decametres and larger, steeply dipping faults dominate and contain a variety of different fault rocks (mylonites, cataclasites, fault gouges). On a smaller scale, somewhat less regular fracture patterns were found. Conceptual models of the fault and fracture geometries and of the properties of rock types adjacent to fractures were derived and used as input for the modelling of in situ dipole tracer tests that were conducted in the framework of the Tracer Retention Understanding Experiment (TRUE-1) on a scale of metres. After the identification of all relevant transport and retardation processes, blind predictions of the breakthroughs of conservative to moderately sorbing tracers were calculated and then compared with the experimental data. This paper provides the geological basis and model calibration, while the predictive and inverse modelling work is the topic of the companion paper [J. Contam. Hydrol. 61 (2003) 175]. The TRUE-1 experimental volume is highly fractured and contains the same types of fault rocks and alterations as on the decametric scale. The experimental flow field was modelled on the basis of a 2D-streamtube formalism with an underlying homogeneous and isotropic transmissivity field. Tracer transport was modelled using the dual porosity medium approach, which is linked to the flow model by the flow porosity. Given the substantial pumping rates in the extraction borehole, the transport domain has a maximum width of a few centimetres only. It is concluded that both the uncertainty with regard to the length of individual fractures and the detailed geometry of the network along the flowpath between injection and extraction boreholes are not critical because flow is largely one-dimensional, whether through a single fracture or a network. Process identification and model calibration were based on a single uranine breakthrough
Influence of Landscape Coverage on Measuring Spatial and Length Properties of Rock Fracture Networks: Insights from Numerical Simulation

Science.gov (United States)

Cao, Wenzhuo; Lei, Qinghua

2018-01-01

Natural fractures are ubiquitous in the Earth's crust and often deeply buried in the subsurface. Due to the difficulty in accessing to their three-dimensional structures, the study of fracture network geometry is usually achieved by sampling two-dimensional (2D) exposures at the Earth's surface through outcrop mapping or aerial photograph techniques. However, the measurement results can be considerably affected by the coverage of forests and other plant species over the exposed fracture patterns. We quantitatively study such effects using numerical simulation. We consider the scenario of nominally isotropic natural fracture systems and represent them using 2D discrete fracture network models governed by fractal and length scaling parameters. The groundcover is modelled as random patches superimposing onto the 2D fracture patterns. The effects of localisation and total coverage of landscape patches are further investigated. The fractal dimension and length exponent of the covered fracture networks are measured and compared with those of the original non-covered patterns. The results show that the measured length exponent increases with the reduced localisation and increased coverage of landscape patches, which is more evident for networks dominated by very large fractures (i.e. small underlying length exponent). However, the landscape coverage seems to have a minor impact on the fractal dimension measurement. The research findings of this paper have important implications for field survey and statistical analysis of geological systems.
Low probability natural phenomena and crustal movement on high level radioactive waste geological disposal

International Nuclear Information System (INIS)

Kusunose, Kinichiro; Sato, Takashi; Cho, Akio; Togashi, Shigeko; Matsumoto, Akikazu; Kanai, Yutaka; Okumura, Koji; Shimokawa, Koichi; Mizuno, Kiyohide

1998-01-01

On subtheme ''development of long-term estimate method of crystal movement'', a control method has been developed under the conditions of 500 MPa confining pressure at 300degC. The method was tested under the conditions of 100 MPa confining pressure at room temperature and the rock fracture experiment was succeeded. On subtheme ''estimation method on the effect of volcanic activity'', in order to evaluate the effects of tephra fall on environment, pollen analysis of sample on outcrop in Sakaida and the topographic and geological survey of river terrace along Nyu-river in Yamagata prefecture were carried out. These results showed number of pollen was decreased immediately after AT tephra fall originated in Kyushu, so that effect of ash on forest was proved. However, the effect of AT tephra fall on ecological system was not so large as changing forest compositing species. On establishment of accurate geologic time measurement of pyroclastic materials, uranium and thorium were chemically separated from various kinds of mineral concentrated materials separated from pyroclastic materials. Iso chron of them was obtained by alpha count. Moreover, a direct geologic time measurement method for distal tephra was developed by pottasium-argon method. It makes possible direct measurement of geological time of young pyroclastic flow sediment. (S.Y.)
Discrete fracture network for the Forsmark site

International Nuclear Information System (INIS)

Darcel, C.; Davy, P.; Bour, O.; Dreuzy, J.R. de

2006-08-01

05A, HFM04 and HFM05) and outcrop DFN models. The main conclusions drawn from the consistency analysis are the following: There exists an important sub horizontal fracturing that occurs close to surface, which makes outcrop fracturing different, in term of density, from the fracturing observed in deep geological units from boreholes. The difference between surface and deep units does not exist for fractures dipping more than 30-40 deg. The rock units are remarkably consistent with outcrops for dips larger than 30-40 deg, and for Model A (a 3d =3.5). Model B tends to predict larger fracture densities in outcrops than in rock units defined in boreholes (in the dip range of 30-40 deg). There is no equivalence, in the outcrops, of the Deformation Zones, identified at depth. The best-fitting model is defined for l min (the smallest fracture diameter consistent with the power law model; l min =2r 0 with r 0 the location parameter) smaller than the borehole diameter. With this method, it is not possible to say more about l min . Models that consider larger values of l min do not ensure the consistency between outcrops and boreholes. The shear zones, as well as the lineaments, may belong to a different global scaling model than rock units. Further investigations and more data are necessary to characterize this additional GSM. Along the project, the issue of DFN model and of the fracture definition consistency across scales is often raised. It should be further investigated, together with a more complete description of the model variability

Geological mapping of investigation trench OL-TK19 at the Olkiluoto study site, Eurajoki, SW Finland

Energy Technology Data Exchange (ETDEWEB)

Eroma, E.; Nordbaeck, N.; Engstroem, J. [Geological Survey of Finland, Espoo (Finland)

2014-12-15

In October 2012, the geological mapping of investigation trench OL-TK19 was carried out by the Geological Survey of Finland at the Olkiluoto study site. The SE-NW trending, ca. 85 m long trench is located in the central part of the Olkiluoto Island next to investigation trenches OL-TK18 and OL-TK4. The lithology in investigation trench OL-TK19 is of heterogeneous character, with rock type varying from veined gneiss, diatexitic gneiss to pegmatitic granite, along with portions of mica gneiss and K-feldspar porphyritic gneiss. In addition, inclusions of mica gneiss, quartz gneiss and skarn are encountered. The rocks have been subjected to a multiphase ductile deformation and the trench is situated in an area where the latest ductile deformation phase, D4 prevails. The investigation trench can be divided into three domains according to its dominant deformation phase and foliation; the eastern part of the trench is dominated by the D3 deformation phase whereas the middle and western parts are dominated by the D4 deformation phase. The S3 foliation has a more ENE-WSW oriented direction whereas the S4 is trending NE-SW. In addition to this difference in orientation, the different structural signature of these two deformation types is observed, the S3 foliation is defined by smaller scaled granitic leucosome veining whereas the S4 foliation is intensely sheared and have a schistose character. During the fracture mapping, all fractures intersecting the central thread were investigated and a total of 132 fractures were recorded. The average fracture frequency 1.53 fractures/m. On the basis of fracture orientations, three fracture sets can be defined. The first set is vertical and NW-SE trending, second set strikes NE-SW with a moderate dip towards the SE and the third set is vertical and NE-SW trending. The median fracture length is 1.38 m and most fractures do not exceed 0.5 m in length, the longest measured fracture being 5.30 m in length. Fracture fillings are mostly
State of the art of numerical modeling of thermohydrologic flow in fractured rock mass

International Nuclear Information System (INIS)

Wang, J.S.Y.; Tsang, C.F.; Sterbentz, R.A.

1983-01-01

The state of the art of numerical modeling of thermohydrologic flow in fractured rock masses is reviewed and a comparative study is made of several models which have been developed in nuclear waste isolation, geothermal energy, ground-water hydrology, petroleum engineering, and other geologic fields. The general review is followed by separate summaries of the main characteristics of the governing equations, numerical solutions, computer codes, validations, and applications for each model
Study on flow and mass transport through fractured soft sedimentary rocks (Contact research)

International Nuclear Information System (INIS)

Shimo, Michito; Kumamoto, Sou; Maekawa, Keisuke

2007-03-01

It is important for safety assessment of HLW geological disposal to evaluate groundwater flow and mass transport in deep underground accurately. Though it is considered that the mass transport in sedimentary rock occurs in pores between grains mainly, fractures of sedimentary rock can be main paths. The objective of this study is to establish a conceptual model for flow and mass transport in fractured soft sedimentary rock. In previous study, a series of laboratory hydraulic and tracer tests and numerical analyses were carried out using sedimentary rock specimens obtained from Koetoi and Wakkanai formation. Single natural fractured cores and rock block specimen were used for the tests and analyses. The results indicated that the matrix diffusion played an important role for mass transport in the fractured soft sedimentary rocks. In this study, the following two tasks were carried out: (1) laboratory hydraulic and tracer experiments of rock cores of Koetoi and Wakkanai formation obtained at HDB-9, HDB-10 and HDB-11 boreholes and a rock block specimen, Wakkanai formation, obtained at an outcrop in the Horonobe area, (2) a numerical study on the conceptual model of flow and mass transport through fractured soft sedimentary rocks. Non-sorbing tracer experiments using naturally fractured cores and rock block specimens were carried out. Pottasium iodide was used as a tracer. The obtained breakthrough curves were interpreted and fitted by using a numerical simulator, and mass transport parameters, such as longitudinal dispersivity, matrix diffusion coefficient, transport aperture, were obtained. Mass transport simulations using a fracture network model, a continuum model and a double porosity model were performed to study the applicability of continuum model and double porosity model for transport in fractured sedimentary rock. (author)
Study of an optimization approach for a disposal tunnel layout, taking into account the geological environment with spatially heterogeneous characteristics

International Nuclear Information System (INIS)

Suyama, Yasuhiro; Toida, Masaru; Yanagizawa, Koichi

2009-01-01

The geological environment has spatially heterogeneous characteristics with varied host rock types, fractures and so on. In this case the generic disposal tunnel layout, which has been designed by JNC, is not the most suitable for HLW disposal in Japan. The existence of spatially heterogeneous characteristics means that in the repository region there exist sub-regions that are more favourable from the perspective of long-term safety and ones that are less favourable. In order that the spatially heterogeneous environment itself may be utilized most effectively as a natural barrier system, an alternative design of disposal tunnel layout is required. Focusing on the geological environment with spatially heterogeneous characteristics, the authors have developed an alternative design of disposal tunnel layout. The alternative design adopts an optimization approach using a variable disposal tunnel layout. The optimization approach minimizes the number of locations where major water-conducting fractures are intersected, and maximizes the number of emplacement locations for waste packages. This paper will outline the variable disposal tunnel layout and its applicability.
Ballistic fractures: indirect fracture to bone.

Science.gov (United States)

Dougherty, Paul J; Sherman, Don; Dau, Nathan; Bir, Cynthia

2011-11-01

Two mechanisms of injury, the temporary cavity and the sonic wave, have been proposed to produce indirect fractures as a projectile passes nearby in tissue. The purpose of this study is to evaluate the temporal relationship of pressure waves using strain gauge technology and high-speed video to elucidate whether the sonic wave, the temporary cavity, or both are responsible for the formation of indirect fractures. Twenty-eight fresh frozen cadaveric diaphyseal tibia (2) and femurs (26) were implanted into ordnance gelatin blocks. Shots were fired using 9- and 5.56-mm bullets traversing through the gelatin only, passing close to the edge of the bone, but not touching, to produce an indirect fracture. High-speed video of the impact event was collected at 20,000 frames/s. Acquisition of the strain data were synchronized with the video at 20,000 Hz. The exact time of fracture was determined by analyzing and comparing the strain gauge output and video. Twenty-eight shots were fired, 2 with 9-mm bullets and 26 with 5.56-mm bullets. Eight indirect fractures that occurred were of a simple (oblique or wedge) pattern. Comparison of the average distance of the projectile from the bone was 9.68 mm (range, 3-20 mm) for fractured specimens and 15.15 mm (range, 7-28 mm) for nonfractured specimens (Student's t test, p = 0.036). In this study, indirect fractures were produced after passage of the projectile. Thus, the temporary cavity, not the sonic wave, was responsible for the indirect fractures.
Use of Groundwater Lifetime Expectancy for the Performance Assessment of Deep Geologic Radioactive Waste Repositories.

Science.gov (United States)

Cornaton, F.; Park, Y.; Normani, S.; Sudicky, E.; Sykes, J.

2005-12-01

Long-term solutions for the disposal of toxic wastes usually involve isolation of the wastes in a deep subsurface geologic environment. In the case of spent nuclear fuel, the safety of the host repository depends on two main barriers: the engineered barrier and the natural geological barrier. If radionuclide leakage occurs from the engineered barrier, the geological medium represents the ultimate barrier that is relied upon to ensure safety. Consequently, an evaluation of radionuclide travel times from the repository to the biosphere is critically important in a performance assessment analysis. In this study, we develop a travel time framework based on the concept of groundwater lifetime expectancy as a safety indicator. Lifetime expectancy characterizes the time radionuclides will spend in the subsurface after their release from the repository and prior to discharging into the biosphere. The probability density function of lifetime expectancy is computed throughout the host rock by solving the backward-in-time solute transport equation subject to a properly posed set of boundary conditions. It can then be used to define optimal repository locations. In a second step, the risk associated with selected sites can be evaluated by simulating an appropriate contaminant release history. The proposed methodology is applied in the context of a typical Canadian Shield environment. Based on a statistically-generated three-dimension network of fracture zones embedded in the granitic host rock, the sensitivity and the uncertainty of lifetime expectancy to the hydraulic and dispersive properties of the fracture network, including the impact of conditioning via their surface expressions, is computed in order to demonstrate the utility of the methodology.
Hydraulic fracture propagation modeling and data-based fracture identification

Science.gov (United States)

Zhou, Jing

Successful shale gas and tight oil production is enabled by the engineering innovation of horizontal drilling and hydraulic fracturing. Hydraulically induced fractures will most likely deviate from the bi-wing planar pattern and generate complex fracture networks due to mechanical interactions and reservoir heterogeneity, both of which render the conventional fracture simulators insufficient to characterize the fractured reservoir. Moreover, in reservoirs with ultra-low permeability, the natural fractures are widely distributed, which will result in hydraulic fractures branching and merging at the interface and consequently lead to the creation of more complex fracture networks. Thus, developing a reliable hydraulic fracturing simulator, including both mechanical interaction and fluid flow, is critical in maximizing hydrocarbon recovery and optimizing fracture/well design and completion strategy in multistage horizontal wells. A novel fully coupled reservoir flow and geomechanics model based on the dual-lattice system is developed to simulate multiple nonplanar fractures' propagation in both homogeneous and heterogeneous reservoirs with or without pre-existing natural fractures. Initiation, growth, and coalescence of the microcracks will lead to the generation of macroscopic fractures, which is explicitly mimicked by failure and removal of bonds between particles from the discrete element network. This physics-based modeling approach leads to realistic fracture patterns without using the empirical rock failure and fracture propagation criteria required in conventional continuum methods. Based on this model, a sensitivity study is performed to investigate the effects of perforation spacing, in-situ stress anisotropy, rock properties (Young's modulus, Poisson's ratio, and compressive strength), fluid properties, and natural fracture properties on hydraulic fracture propagation. In addition, since reservoirs are buried thousands of feet below the surface, the
Geologic map of the Themis Regio quadrangle (V-53), Venus

Science.gov (United States)

Stofan, Ellen R.; Brian, Antony W.

2012-01-01

The Themis Regio quadrangle (V-53), Venus, has been geologically mapped at 1:5,000,000 scale as part of the NASA Planetary Geologic Mapping Program. The quadrangle extends from lat 25° to 50° S. and from long 270° to 300° E. and encompasses the Themis Regio highland, the surrounding plains, and the southernmost extension of Parga Chasmata. Themis Regio is a broad regional topographic high with a diameter of about 2,000 km and a height of about 0.5 km that has been interpreted previously as a hotspot underlain by a mantle plume. The Themis rise is dominated by coronae and lies at the terminus of the Parga Chasmata corona chain. Themis Regio is the only one of the three corona-dominated rises that contains significant extensional deformation. Fractures and grabens are much less common than along the rest of Parga Chasmata and are embayed by corona-related flows in places. Rift and corona formation has overlapped in time at Themis Regio.
Questions on geology in connection with final radioactive waste disposal in the Fennoscandian Shield

International Nuclear Information System (INIS)

Bjoerklund, A.

1990-01-01

The use of nuclear power involves handling and disposal of radioactive waste. A number of methods for disposal have been proposed, one of which is the construction of repositories in crystalline bedrock of old continental crust. This possibility is usually considered reliable because of the relative stability of such bedrock. The Fennoscandian area has repeatedly been glaciated during the past 3 mission years. The last glacial event terminated some 10 000 years ago. This glacial ''massage'' has maintained a dense network of fractures and faults open for circulating water and ascending gas. Blocks of relatively unfractured bedrock have been proposed as suitable sites for the disposal of nuclear waste. Such questions concern neotectonic activity, the movement, salt content and amount of water at a few hundred metres depth, the mobility of elements in the bedrock as well as the geological processes which might be active beneath any future ice cap. Deep groundwaters, dating of young fracture minerals and neotectonic movements have been studied during 1985 - 1989 in a Nordic reserach program sponsored by NKA, the Nordic Liaison Committee for Atomic Energy. Deep saline groundwaters may have a negative effect on repositories of nuclear waste and the knowledge of the location of such waters may also give a hint as to the pattern of water movement in the bedrock. Therefore the composition, origin and location of deep groundwaters were studied. The development of faults in the bedrock through a site of waste disposal before the radioactivity in the waste has decayed to a safe level is considered a serious risk factor. Neotectonic movements have mostly followed old faults and fracture zones in the bedrock, which repeatedly have been reactivated during geological time, leaving blocks between the faults tectonically undisturbed. (CLS) 80 refs
Structural geology and geophysics as a support to build a hydrogeologic model of granite rock

Science.gov (United States)

Martinez-Landa, Lurdes; Carrera, Jesús; Pérez-Estaún, Andrés; Gómez, Paloma; Bajos, Carmen

2016-06-01

A method developed for low-permeability fractured media was applied to understand the hydrogeology of a mine excavated in a granitic pluton. This method includes (1) identifying the main groundwater-conducting features of the medium, such as the mine, dykes, and large fractures, (2) implementing this factors as discrete elements into a three-dimensional numerical model, and (3) calibrating these factors against hydraulic data . A key question is how to identify preferential flow paths in the first step. Here, we propose a combination of several techniques. Structural geology, together with borehole sampling, geophysics, hydrogeochemistry, and local hydraulic tests aided in locating all structures. Integration of these data yielded a conceptual model of the site. A preliminary calibration of the model was performed against short-term (Model validity was tested by blind prediction of a long-term (4 months) large-scale (1 km) pumping test from the mine, which yielded excellent agreement with the observations. Model results confirmed the sparsely fractured nature of the pluton, which has not been subjected to glacial loading-unloading cycles and whose waters are of Na-HCO3 type.
Geomechanical Framework for Secure CO₂ Storage in Fractured Reservoirs and Caprocks for Sedimentary Basins in theMidwest United States

Energy Technology Data Exchange (ETDEWEB)

Sminchak, Joel [Battelle, Columbus, OH (United States)

2017-09-29

This report presents final technical results for the project Geomechanical Framework for Secure CO₂ Storage in Fractured Reservoirs and Caprocks for Sedimentary Basins in the Midwest United States (DE-FE0023330). The project was a three-year effort consisting of seven technical tasks focused on defining geomechanical factors for CO₂ storage applications in deep saline rock formations in Ohio and the Midwest United States, because geomechancial issues have been identified as a significant risk factor for large-scale CO₂ storage applications. A basin-scale stress-strain analysis was completed to describe the geomechanical setting for rock formations of Ordovician-Cambrian age in Ohio and adjacent areas of the Midwest United States in relation to geologic CO₂ storage applications. The tectonic setting, stress orientation-magnitude, and geomechanical and petrophysical parameters for CO₂ storage zones and caprocks in the region were cataloged. Ten geophysical image logs were analyzed for natural fractures, borehole breakouts, and drilling-induced fractures. The logs indicated mostly less than 10 fractures per 100 vertical feet in the borehole, with mostly N65E principal stress orientation through the section. Geophysical image logs and other logs were obtained for three wells located near the sites where specific models were developed for geomechanical simulations: Arches site in Boone County, Kentucky; Northern Appalachian Basin site in Chautauqua County, New York; and E-Central Appalachian Basin site in Tuscarawas County, Ohio. For these three wells, 9,700 feet of image logs were processed and interpreted to provide a systematic review of the distribution within each well of natural fractures, wellbore breakouts, faults, and drilling induced fractures. There were many borehole breakouts and drilling-induced tensile fractures but few natural fractures. Concentrated fractures were present at the Rome-basal sandstone
Distinguishing stress fractures from pathologic fractures: a multimodality approach

International Nuclear Information System (INIS)

Fayad, Laura M.; Kamel, Ihab R.; Kawamoto, Satomi; Bluemke, David A.; Fishman, Elliot K.; Frassica, Frank J.

2005-01-01

Whereas stress fractures occur in normal or metabolically weakened bones, pathologic fractures occur at the site of a bone tumor. Unfortunately, stress fractures may share imaging features with pathologic fractures on plain radiography, and therefore other modalities are commonly utilized to distinguish these entities. Additional cross-sectional imaging with CT or MRI as well as scintigraphy and PET scanning is often performed for further evaluation. For the detailed assessment of a fracture site, CT offers a high-resolution view of the bone cortex and periosteum which aids the diagnosis of a pathologic fracture. The character of underlying bone marrow patterns of destruction can also be ascertained along with evidence of a soft tissue mass. MRI, however, is a more sensitive technique for the detection of underlying bone marrow lesions at a fracture site. In addition, the surrounding soft tissues, including possible involvement of adjacent muscle, can be well evaluated with MRI. While bone scintigraphy and FDG-PET are not specific, they offer a whole-body screen for metastases in the case of a suspected malignant pathologic fracture. In this review, we present select examples of fractures that underscore imaging features that help distinguish stress fractures from pathologic fractures, since accurate differentiation of these entities is paramount. (orig.)
Proceedings of the Workshop on near-field phenomena in geologic repositories for radioactive waste

Energy Technology Data Exchange (ETDEWEB)

1981-01-01

Prediction of the behaviour of radioactive waste and the geologic host medium is a complex problem, involving an understanding of many chemical and physical phenomena. Topics covered by this Workshop include rock mechanics in stressed and heated conditions; thermally induced groundwater flow in fractured rock; chemical changes to rock surfaces associated with groundwater and changes in the thermal and chemical environment; the chemical solubilities and sorption properties of radionuclides; and the long-term integrity of containers and packaging for radioactive waste.
Double segmental tibial fractures - an unusual fracture pattern

Directory of Open Access Journals (Sweden)

Bali Kamal

2012-02-01

Full Text Available 【Abstract】A case of a 50-year-old pedestrian who was hit by a bike and suffered fractures of both bones of his right leg was presented. Complete clinical and radiographic assessment showed double segmental fractures of the tibia and multisegmental fractures of the fibula. Review of the literature revealed that this fracture pattern was unique and only a single case was reported so far. Moreover, we discussed the possible mechanisms which can lead to such an injury. We also discussed the management of segmental tibial fracture and the difficulties encountered with them. This case was managed by modern osteosynthesis tech- nique with a pleasing outcome. Key words: Fracture, bone; Tibia; Fibula; Nails
Occurrence of fracture-lining manganese minerals in silicic tuffs, Yucca Mountain, Nevada, USA

International Nuclear Information System (INIS)

Carlos, B.A.

1986-01-01

Yucca Mountain, in southern Nevada, is being studied by the Nevada Nuclear Waste Storage Investigations (NNWSI) Project as a potential site for an underground high-level nuclear waste repository. The site is within Miocene volcanic rocks that are 1.5 to 4 km thick and range in age from 12.5 to 14 MY. Several holes have been drilled in Yucca Mountain for geologic and hydrologic studies. Drill hole USW G-4, the most recently cored hole within the potential repository block, was chosen for detailed study of fracture-filling minerals because it is closest to the planned NNWSI exploratory shaft. Drill hole USW G-4 was drilled to 914.7 m (3001 ft) and continuously cored from 6.7 m (22 ft) to total depth (TD). The drilling history, lithology of the core, and geophysical logs of the well were published earlier. Because manganese oxides in fractures may act as a natural barrier to radionuclide migration, it is important to determine exactly which manganese minerals are present, in what intervals they occur, and how extensive these fracture coatings are
Structural geology mapping using PALSAR data in the Bau gold mining district, Sarawak, Malaysia

Science.gov (United States)

Pour, Amin Beiranvand; Hashim, Mazlan

2014-08-01

The application of optical remote sensing data for geological mapping is difficult in the tropical environment. The persistent cloud coverage, dominated vegetation in the landscape and limited bedrock exposures are constraints imposed by the tropical climate. Structural geology investigations that are searching for epithermal or polymetallic vein-type ore deposits can be developed using Synthetic Aperture Radar (SAR) remote sensing data in tropical/sub-tropical regions. The Bau gold mining district in the State of Sarawak, East Malaysia, on the island of Borneo has been selected for this study. The Bau is a gold field similar to Carlin style gold deposits, but gold mineralization at Bau is much more structurally controlled. Geological analyses coupled with the Phased Array type L-band Synthetic Aperture Radar (PALSAR) remote sensing data were used to detect structural elements associated with gold mineralization. The PALSAR data were used to perform lithological-structural mapping of mineralized zones in the study area and surrounding terrain. Structural elements were detected along the SSW to NNE trend of the Tuban fault zone and Tai Parit fault that corresponds to the areas of occurrence of the gold mineralization in the Bau Limestone. Most of quartz-gold bearing veins occur in high-angle faults, fractures and joints within massive units of the Bau Limestone. The results show that four deformation events (D1-D4) in the structures of the Bau district and structurally controlled gold mineralization indicators, including faults, joints and fractures are detectable using PALSAR data at both regional and district scales. The approach used in this study can be more broadly applicable to provide preliminary information for exploration potentially interesting areas of epithermal or polymetallic vein-type mineralization using the PALSAR data in the tropical/sub-tropical regions.
Numerical modeling of radionuclide migration in water-saturated planar fracture: study of performance of bentonite in the far-field region

Energy Technology Data Exchange (ETDEWEB)

Silveira, Claudia S. da; Alvim, Antonio C.M., E-mail: csilveira@con.ufrj.b [Universidade Federal do Rio de Janeiro (PEN/COPPE/UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia. Programa de Energia Nuclear

2011-07-01

The analysis of radionuclide migration in fractured porous media is an important part of the safety assessment of a deep geologic disposal for high level radioactive wastes. In this work, numerical solution for simple geometry was developed to study radionuclide migration, including decay chain from a hypothetical repository, whereas the initial region of fracture is filled with bentonite which expanded from EBS (Engineered Barrier System). The following cases were considered: convective transport with constant velocity along the fracture, longitudinal hydrodynamic dispersion in the fracture along the fracture axis, molecular diffusion from fracture into rock matrix, sorption within rock matrix, sorption onto the surface of the fracture, radioactive decay, decay chain, and diffusion in bentonite extrusion region. For conservative analysis, the porous matrix adjacent to the fracture was subdivided into two different subdomains, each with different set of parameters and considering that the radionuclides were available for migration in the solubility limit, at fracture inlet, from the initial time. The partial differential equations that govern the physical system were discretized by finite differences, by using the Implicit Euler Method with forward scheme in the convective term. In this study, numerical simulation was performed for 100, 1000 and 10000 years, with and without bentonite extrusion, in order to compare the migration retardation obtained by bentonite located at the beginning of the fracture in saturated environment. The numerical simulation results showed the importance of extruded area in the far field region of the fractured host rock. (author)
Numerical modeling of radionuclide migration in water-saturated planar fracture: study of performance of bentonite in the far-field region

International Nuclear Information System (INIS)

Silveira, Claudia S. da; Alvim, Antonio C.M.

2011-01-01

The analysis of radionuclide migration in fractured porous media is an important part of the safety assessment of a deep geologic disposal for high level radioactive wastes. In this work, numerical solution for simple geometry was developed to study radionuclide migration, including decay chain from a hypothetical repository, whereas the initial region of fracture is filled with bentonite which expanded from EBS (Engineered Barrier System). The following cases were considered: convective transport with constant velocity along the fracture, longitudinal hydrodynamic dispersion in the fracture along the fracture axis, molecular diffusion from fracture into rock matrix, sorption within rock matrix, sorption onto the surface of the fracture, radioactive decay, decay chain, and diffusion in bentonite extrusion region. For conservative analysis, the porous matrix adjacent to the fracture was subdivided into two different subdomains, each with different set of parameters and considering that the radionuclides were available for migration in the solubility limit, at fracture inlet, from the initial time. The partial differential equations that govern the physical system were discretized by finite differences, by using the Implicit Euler Method with forward scheme in the convective term. In this study, numerical simulation was performed for 100, 1000 and 10000 years, with and without bentonite extrusion, in order to compare the migration retardation obtained by bentonite located at the beginning of the fracture in saturated environment. The numerical simulation results showed the importance of extruded area in the far field region of the fractured host rock. (author)
Ankle fracture spur sign is pathognomonic for a variant ankle fracture.

Science.gov (United States)

Hinds, Richard M; Garner, Matthew R; Lazaro, Lionel E; Warner, Stephen J; Loftus, Michael L; Birnbaum, Jacqueline F; Burket, Jayme C; Lorich, Dean G

2015-02-01

The hyperplantarflexion variant ankle fracture is composed of a posterior tibial lip fracture with posterolateral and posteromedial fracture fragments separated by a vertical fracture line. This infrequently reported injury pattern often includes an associated "spur sign" or double cortical density at the inferomedial tibial metaphysis. The objective of this study was to quantitatively establish the association of the ankle fracture spur sign with the hyperplantarflexion variant ankle fracture. Our clinical database of operative ankle fractures was retrospectively reviewed for the incidence of hyperplantarflexion variant and nonvariant ankle fractures as determined by assessment of injury radiographs, preoperative advanced imaging, and intraoperative observation. Injury radiographs were then evaluated for the presence of the spur sign, and association between the spur sign and variant fractures was analyzed. The incidence of the hyperplantarflexion variant fracture among all ankle fractures was 6.7% (43/640). The spur sign was present in 79% (34/43) of variant fractures and absent in all nonvariant fractures, conferring a specificity of 100% in identifying variant fractures. Positive predictive value and negative predictive value were 100% and 99%, respectively. The ankle fracture spur sign was pathognomonic for the hyperplantarflexion variant ankle fracture. It is important to identify variant fractures preoperatively as patient positioning, operative approach, and fixation construct of variant fractures often differ from those employed for osteosynthesis of nonvariant fractures. Identification of the spur sign should prompt acquisition of advanced imaging to formulate an appropriate operative plan to address the variant fracture pattern. Level III, retrospective comparative study. © The Author(s) 2014.
Association of Ipsilateral Rib Fractures With Displacement of Midshaft Clavicle Fractures.

Science.gov (United States)

Stahl, Daniel; Ellington, Matthew; Brennan, Kindyle; Brennan, Michael

2017-04-01

To determine whether the presence of ipsilateral rib fractures affects the rate of a clavicle fracture being unstable (>100% displacement). A retrospective review from 2002-2013 performed at a single level 1 trauma center evaluated 243 midshaft clavicle fractures. Single Level 1 trauma center. These fractures were subdivided into those with ipsilateral rib fractures (CIR; n = 149) and those without ipsilateral rib fractures (CnIR; n = 94). The amount of displacement was measured on the initial injury radiograph and subsequent follow-up radiographs. Fractures were classified into either 100% displacement, based on anteroposterior radiographs. Ipsilateral rib fractures were recorded based on which number rib was fractured and the total number of fractured ribs. One hundred sixteen (78%) of the CIR group and 51 (54%) of the CnIR group were found to have >100% displacement at follow-up (P = 0.0047). Seventy-two percent of the CIR group demonstrated progression from 100% displacement of the fracture compared with only 54% of the CnIR group (P fracture to >100% was 4.08 (P = 0.000194) when ribs 1-4 were fractured and not significant for rib fractures 5-8 or 9-12. The presence of concomitant ipsilateral rib fractures significantly increases the rate of midshaft clavicle fractures being >100% displaced. In addition, a fracture involving the upper one-third of the ribs significantly increases the rate of the clavicle fracture being >100% displaced on early follow-up. Clavicle fractures with associated ipsilateral rib fractures tend to demonstrate an increased amount of displacement on follow-up radiographs compared with those without ipsilateral rib fractures. Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.

Fractures inside crystalline rocks. Effects of deformations on fluid circulations

International Nuclear Information System (INIS)

Gentier, S.

2005-01-01

The modeling of fluid flows inside granite massifs is an important task for the evaluation of the feasibility of radioactive waste storage inside such formations. This document makes a synthesis of the works carried out since about 15 years, in particular by the French bureau of geological and mining research (BRGM), about the hydro-mechanical behaviour of a fracture and about the hydrodynamical characterization of fracture networks inside crystalline rocks: 1 - introduction; 2 - hydro-mechanical behaviour under normal stress: experimental results (hydro-mechanical behaviour, flow regimes, mechanical behaviour, test protocol, complementary tests, influence of samples size), geometrical interpretation of experimental results (relation with walls geometry, relation with voids geometry, relation with contacts geometry), hydro-mechanical modeling (hydraulic modeling, mechanical modeling); 3 - from the hydro-mechanical behaviour under normal stress to the coupling with heat transfers and chemistry: experiment for the study of the chemo-thermo-hydro-mechanical coupling (experimental results, relation with walls morphology), thermo-hydro-mechanical experiments, thermo-hydro-chemical experiments with fractures, conclusions; 4 - hydro-mechanical behaviour during shear: experimental results, geometrical interpretation (relation with the geometry of damaged zones, relation with voids geometry, relation with walls geometry), hydro-mechanical modeling (mechanical modeling, hydro-mechanical modeling of the behaviour during shear). (J.S.)
Geological, Geophysical, And Thermal Characteristics Of The Salton Sea Geothermal Field, California

Energy Technology Data Exchange (ETDEWEB)

Younker, L.W.; Kasameyer, P. W.; Tewhey, J. D.

1981-01-01

The Salton Sea Geothermal Field is the largest water-dominated geothermal field in the Salton Trough in Southern California. Within the trough, local zones of extension among active right-stepping right-lateral strike-slip faults allow mantle-derived magmas to intrude the sedimentary sequence. The intrusions serves as heat sources to drive hydrothermal systems. We can characterize the field in detail because we have an extensive geological and geophysical data base. The sediments are relatively undeformed and can be divided into three categories as a function of depth: (1) low-permeability cap rock, (2) upper reservoir rocks consisting of sandstones, siltstones, and shales that were subject to minor alterations, and (3) lower reservoir rocks that were extensively altered. Because of the alteration, intergranular porosity and permeability are reduced with depth. permeability is enhanced by renewable fractures, i.e., fractures that can be reactivated by faulting or natural hydraulic fracturing subsequent to being sealed by mineral deposition. In the central portion of the field, temperature gradients are high near the surface and lower below 700 m. Surface gradients in this elliptically shaped region are fairly constant and define a thermal cap, which does not necessarily correspond to the lithologic cap. At the margin of the field, a narrow transition region, with a low near-surface gradient and an increasing gradient at greater depths, separates the high temperature resource from areas of normal regional gradient. Geophysical and geochemical evidence suggest that vertical convective motion in the reservoir beneath the thermal cap is confined to small units, and small-scale convection is superimposed on large-scale lateral flow of pore fluid. Interpretation of magnetic, resistivity, and gravity anomalies help to establish the relationship between the inferred heat source, the hydrothermal system, and the observed alteration patterns. A simple hydrothermal model is
Geological model of supercritical geothermal reservoir related to subduction system

Science.gov (United States)

Tsuchiya, Noriyoshi

2017-04-01

Following the Great East Japan Earthquake and the accident at the Fukushima Daiichi Nuclear power station on 3.11 (11th March) 2011, geothermal energy came to be considered one of the most promising sources of renewable energy for the future in Japan. The temperatures of geothermal fields operating in Japan range from 200 to 300 °C (average 250 °C), and the depths range from 1000 to 2000 m (average 1500 m). In conventional geothermal reservoirs, the mechanical behavior of the rocks is presumed to be brittle, and convection of the hydrothermal fluid through existing network is the main method of circulation in the reservoir. In order to minimize induced seismicity, a rock mass that is "beyond brittle" is one possible candidate, because the rock mechanics of "beyond brittle" material is one of plastic deformation rather than brittle failure. Supercritical geothermal resources could be evaluated in terms of present volcanic activities, thermal structure, dimension of hydrothermal circulation, properties of fracture system, depth of heat source, depth of brittle factures zone, dimension of geothermal reservoir. On the basis of the GIS, potential of supercritical geothermal resources could be characterized into the following four categories. 1. Promising: surface manifestation d shallow high temperature, 2 Probability: high geothermal gradient, 3 Possibility: Aseismic zone which indicates an existence of melt, 4 Potential : low velocity zone which indicates magma input. Base on geophysical data for geothermal reservoirs, we have propose adequate tectonic model of development of the supercritical geothermal reservoirs. To understand the geological model of a supercritical geothermal reservoir, granite-porphyry system, which had been formed in subduction zone, was investigated as a natural analog of the supercritical geothermal energy system. Quartz veins, hydrothermal breccia veins, and glassy veins are observed in a granitic body. The glassy veins formed at 500-550 �
China organic-rich shale geologic features and special shale gas production issues

Directory of Open Access Journals (Sweden)

Yiwen Ju

2014-06-01

Full Text Available The depositional environment of organic-rich shale and the related tectonic evolution in China are rather different from those in North America. In China, organic-rich shale is not only deposited in marine environment, but also in non-marine environment: marine-continental transitional environment and lacustrine environment. Through analyzing large amount of outcrops and well cores, the geologic features of organic-rich shale, including mineral composition, organic matter richness and type, and lithology stratigraphy, were analyzed, indicating very special characteristics. Meanwhile, the more complex and active tectonic movements in China lead to strong deformation and erosion of organic-rich shale, well-development of fractures and faults, and higher thermal maturity and serious heterogeneity. Co-existence of shale gas, tight sand gas, and coal bed methane (CBM proposes a new topic: whether it is possible to co-produce these gases to reduce cost. Based on the geologic features, the primary production issues of shale gas in China were discussed with suggestions.
Development of performance assessment methodology for nuclear waste isolation in geologic media

Science.gov (United States)

Bonano, E. J.; Chu, M. S. Y.; Cranwell, R. M.; Davis, P. A.

The burial of nuclear wastes in deep geologic formations as a means for their disposal is an issue of significant technical and social impact. The analysis of the processes involved can be performed only with reliable mathematical models and computer codes as opposed to conducting experiments because the time scales associated are on the order of tens of thousands of years. These analyses are concerned primarily with the migration of radioactive contaminants from the repository to the environment accessible to humans. Modeling of this phenomenon depends on a large number of other phenomena taking place in the geologic porous and/or fractured medium. These are ground-water flow, physicochemical interactions of the contaminants with the rock, heat transfer, and mass transport. Once the radionuclides have reached the accessible environment, the pathways to humans and health effects are estimated. A performance assessment methodology for a potential high-level waste repository emplaced in a basalt formation has been developed for the U.S. Nuclear Regulatory Commission.
Synthetic geology - Exploring the "what if?" in geology

Science.gov (United States)

Klump, J. F.; Robertson, J.

2015-12-01

The spatial and temporal extent of geological phenomena makes experiments in geology difficult to conduct, if not entirely impossible and collection of data is laborious and expensive - so expensive that most of the time we cannot test a hypothesis. The aim, in many cases, is to gather enough data to build a predictive geological model. Even in a mine, where data are abundant, a model remains incomplete because the information at the level of a blasting block is two orders of magnitude larger than the sample from a drill core, and we have to take measurement errors into account. So, what confidence can we have in a model based on sparse data, uncertainties and measurement error? Synthetic geology does not attempt to model the real world in terms of geological processes with all their uncertainties, rather it offers an artificial geological data source with fully known properties. On the basis of this artificial geology, we can simulate geological sampling by established or future technologies to study the resulting dataset. Conducting these experiments in silico removes the constraints of testing in the field or in production, and provides us with a known ground-truth against which the steps in a data analysis and integration workflow can be validated.Real-time simulation of data sources can be used to investigate crucial questions such as the potential information gain from future sensing capabilities, or from new sampling strategies, or the combination of both, and it enables us to test many "what if?" questions, both in geology and in data engineering. What would we be able to see if we could obtain data at higher resolution? How would real-time data analysis change sampling strategies? Does our data infrastructure handle many new real-time data streams? What feature engineering can be deducted for machine learning approaches? By providing a 'data sandbox' able to scale to realistic geological scenarios we hope to start answering some of these questions.
Geologic mapping of the Amirani-Gish Bar region of Io: Implications for the global geologic mapping of Io

Science.gov (United States)

Williams, D.A.; Keszthelyi, L.P.; Crown, D.A.; Jaeger, W.L.; Schenk, P.M.

2007-01-01

We produced the first geologic map of the Amirani-Gish Bar region of Io, the last of four regional maps generated from Galileo mission data. The Amirani-Gish Bar region has five primary types of geologic materials: plains, mountains, patera floors, flows, and diffuse deposits. The flows and patera floors are thought to be compositionally similar, but are subdivided based on interpretations regarding their emplacement environments and mechanisms. Our mapping shows that volcanic activity in the Amirani-Gish Bar region is dominated by the Amirani Eruptive Center (AEC), now recognized to be part of an extensive, combined Amirani-Maui flow field. A mappable flow connects Amirani and Maui, suggesting that Maui is fed from Amirani, such that the post-Voyager designation "Maui Eruptive Center" should be revised. Amirani contains at least four hot spots detected by Galileo, and is the source of widespread bright (sulfur?) flows and active dark (silicate?) flows being emplaced in the Promethean style (slowly emplaced, compound flow fields). The floor of Gish Bar Patera has been partially resurfaced by dark lava flows, although other parts of its floor are bright and appeared unchanged during the Galileo mission. This suggests that the floor did not undergo complete resurfacing as a lava lake as proposed for other ionian paterae. There are several other hot spots in the region that are the sources of both active dark flows (confined within paterae), and SO2- and S2-rich diffuse deposits. Mapped diffuse deposits around fractures on mountains and in the plains appear to serve as the source for gas venting without the release of magma, an association previously unrecognized in this region. The six mountains mapped in this region exhibit various states of degradation. In addition to gaining insight into this region of Io, all four maps are studied to assess the best methodology to use to produce a new global geologic map of Io based on the newly released, combined Galileo
A Rare Nasal Bone Fracture: Anterior Nasal Spine Fracture

Directory of Open Access Journals (Sweden)

Egemen Kucuk

2014-04-01

Full Text Available Anterior nasal spine fractures are a quite rare type of nasal bone fractures. Associated cervical spine injuries are more dangerous than the nasal bone fracture. A case of the anterior nasal spine fracture, in a 18-year-old male was presented. Fracture of the anterior nasal spine, should be considered in the differential diagnosis of the midface injuries and also accompanying cervical spine injury should not be ignored.
Numerical Simulation of Permeability Change in Wellbore Cement Fractures after Geomechanical Stress and Geochemical Reactions Using X-ray Computed Tomography Imaging.

Science.gov (United States)

Kabilan, Senthil; Jung, Hun Bok; Kuprat, Andrew P; Beck, Anthon N; Varga, Tamas; Fernandez, Carlos A; Um, Wooyong

2016-06-21

X-ray microtomography (XMT) imaging combined with three-dimensional (3D) computational fluid dynamics (CFD) modeling technique was used to study the effect of geochemical and geomechanical processes on fracture permeability in composite Portland cement-basalt caprock core samples. The effect of fluid density and viscosity and two different pressure gradient conditions on fracture permeability was numerically studied by using fluids with varying density and viscosity and simulating two different pressure gradient conditions. After the application of geomechanical stress but before CO2-reaction, CFD revealed fluid flow increase, which resulted in increased fracture permeability. After CO2-reaction, XMT images displayed preferential precipitation of calcium carbonate within the fractures in the cement matrix and less precipitation in fractures located at the cement-basalt interface. CFD estimated changes in flow profile and differences in absolute values of flow velocity due to different pressure gradients. CFD was able to highlight the profound effect of fluid viscosity on velocity profile and fracture permeability. This study demonstrates the applicability of XMT imaging and CFD as powerful tools for characterizing the hydraulic properties of fractures in a number of applications like geologic carbon sequestration and storage, hydraulic fracturing for shale gas production, and enhanced geothermal systems.
Geology and structure of the Malpaso caldera and El Ocote ignimbrite, Aguascalientes, Mexico

International Nuclear Information System (INIS)

Nieto-Obregon, Jorge; Aguirre-DIaz, Gerardo

2008-01-01

A new caldera, named Malpaso, is reported west of the city of Aguascalientes, Mexico. The Malpaso caldera is a volcano-tectonic depression, highly fractured and faulted, and was filled by voluminous pyroclastic products related to the caldera collapse. Due to these characteristics it as a graben caldera. It is truncated by younger normal faults of the Calvillo and Aguascalientes grabens. In this work we present a summary of the geologic and structural observations on this caldera, as well as a description of the main caldera product, the high-grade El Ocote ignimbrite.
Geology and structure of the Malpaso caldera and El Ocote ignimbrite, Aguascalientes, Mexico

Energy Technology Data Exchange (ETDEWEB)

Nieto-Obregon, Jorge [Facultad de IngenierIa, UNAM, Coyoacan, 04510, Mexico D.F. (Mexico); Aguirre-DIaz, Gerardo [Centro de Geociencias, UNAM, Campus Juriquilla, 76220, Queretaro, Qro. (Mexico)], E-mail: nieto@servidor.unam.mx, E-mail: ger@geociencias.unam.mx

2008-10-01

A new caldera, named Malpaso, is reported west of the city of Aguascalientes, Mexico. The Malpaso caldera is a volcano-tectonic depression, highly fractured and faulted, and was filled by voluminous pyroclastic products related to the caldera collapse. Due to these characteristics it as a graben caldera. It is truncated by younger normal faults of the Calvillo and Aguascalientes grabens. In this work we present a summary of the geologic and structural observations on this caldera, as well as a description of the main caldera product, the high-grade El Ocote ignimbrite.
Predicting dissolution patterns in variable aperture fractures: 1. Development and evaluation of an enhanced depth-averaged computational model

Energy Technology Data Exchange (ETDEWEB)

Detwiler, R L; Rajaram, H

2006-04-21

Water-rock interactions within variable-aperture fractures can lead to dissolution of fracture surfaces and local alteration of fracture apertures, potentially transforming the transport properties of the fracture over time. Because fractures often provide dominant pathways for subsurface flow and transport, developing models that effectively quantify the role of dissolution on changing transport properties over a range of scales is critical to understanding potential impacts of natural and anthropogenic processes. Dissolution of fracture surfaces is controlled by surface-reaction kinetics and transport of reactants and products to and from the fracture surfaces. We present development and evaluation of a depth-averaged model of fracture flow and reactive transport that explicitly calculates local dissolution-induced alterations in fracture apertures. The model incorporates an effective mass transfer relationship that implicitly represents the transition from reaction-limited dissolution to transport-limited dissolution. We evaluate the model through direct comparison to previously reported physical experiments in transparent analog fractures fabricated by mating an inert, transparent rough surface with a smooth single crystal of potassium dihydrogen phosphate (KDP), which allowed direct measurement of fracture aperture during dissolution experiments using well-established light transmission techniques [Detwiler, et al., 2003]. Comparison of experiments and simulations at different flow rates demonstrate the relative impact of the dimensionless Peclet and Damkohler numbers on fracture dissolution and the ability of the computational model to simulate dissolution. Despite some discrepancies in the small-scale details of dissolution patterns, the simulations predict the evolution of large-scale features quite well for the different experimental conditions. This suggests that our depth-averaged approach to simulating fracture dissolution provides a useful approach for
The state of the art of numerical modeling of thermohydrologic flow in fractured rock masses

International Nuclear Information System (INIS)

Wang, J.S.Y.; Sterbentz, R.A.; Tsang, C.F.

1982-01-01

The state of the art of numerical modeling of thermohydrologic flow in fractured rock masses is reviewed and a comparative study is made of several models which have been developed in nuclear waste isolation, geothermal energy, ground water hydrology, petroleum engineering, and other geologic fields. The general review is followed by individual summaries of each model and the main characteristics of its governing equations, numerical solutions, computer codes, validations, and applications
Study of the effect of moisture content and bending rate on the fracture toughness of rocks

Czech Academy of Sciences Publication Activity Database

Vavro, Leona; Souček, Kamil

2013-01-01

Roč. 10, č. 2 (2013), s. 247-253 ISSN 1214-9705 R&D Projects: GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : fracture toughness * bending rate * tensile strength Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.667, year: 2013 http://www.irsm.cas.cz/materialy/acta_content/2013_02/acta_170_14_Vavro_Soucek_247-253.pdf
Geology, geophysics, and physical properties of the U12n.25 non-proliferation experiment site

Energy Technology Data Exchange (ETDEWEB)

Baldwin, M.J.; Bradford, R.P.; Hopkins, S.P. [Raytheon Services Nevada, Mercury, NV (United States)] [and others

1994-12-31

The Nuclear Non-Proliferation Experiment was conducted in the U12n.25 drift in N-Tunnel at the Nevada Test Site. The geologic characterization of the site was performed by Raytheon Services Nevada geologists in the standard manner used for all underground nuclear weapons-effects tests executed by the Defense Nuclear Agency. The U12n.25 test bed was constructed in zeolitized ash-fall tuff of the Tunnel Beds Tuff, Subunit 4K, 389.0 m below the surface of Rainier Mesa. The structural geology of the site was simple, with the nearest fault plane projected to be 12 m below the mined cavity at closest approach, and an average bedding dip of seven degrees to the northwest. The cavity excavation revealed several small fractures, including one which produced minor amounts of free water during construction. The physical properties of the site were well within the range of experience for the zeolitized tuff of N-Tunnel and no geology-related problems were encountered during construction. The zeolitized tuff of N-Tunnel has been the site of twenty nuclear tests conducted by the Defense Nuclear Agency. The similarities of geologic setting, site geometry, and physical properties allow many comparisons of Non-Proliferation Experiment results with the large nuclear-test data base.
Fracture of the styloid process associated with the mandible fracture

Directory of Open Access Journals (Sweden)

K N Dubey

2013-01-01

Full Text Available Fracture of the styloid process (SP of temporal bone is an uncommon injuries. Fracture of the SP can be associated with the facial injuries including mandible fracture. However, injury to the SP may be concealed and missed diagnosis may lead to the improper or various unnecessary treatments. A rare case of SP fracture associated with the ipsilateral mandibular fracture and also the diagnostic and management considerations of the SP fracture are discussed.
New developments in measurements technology relevant to the studies of deep geological repositories in bedded salt

International Nuclear Information System (INIS)

Mao, N.; Ramirez, A.L.

1980-01-01

This report presents new developments in measurement technology relevant to the studies of deep geological repositories for nuclear waste disposal during all phases of development, i.e., site selection, site characterization, construction, operation, and decommission. Emphasis has been placed on geophysics and geotechnics with special attention to those techniques applicable to bedded salt. The techniques are grouped into sections as follows: tectonic environment, state of stress, subsurface structures, fractures, stress changes, deformation, thermal properties, fluid transport properties, and other approaches. Several areas that merit further research and developments are identified. These areas are: in situ thermal measurement techniques, fracture detection and characterization, in situ stress measurements, and creep behavior. The available instrumentations should generally be improved to have better resolution and accuracy, enhanced instrument survivability, and reliability for extended time periods in a hostile environment
New developments in measurements technology relevant to the studies of deep geological repositories in bedded salt

Science.gov (United States)

Mao, N. H.; Ramirez, A. L.

1980-10-01

Developments in measurement technology are presented which are relevant to the studies of deep geological repositories for nuclear waste disposal during all phases of development, i.e., site selection, site characterization, construction, operation, and decommission. Emphasis was placed on geophysics and geotechnics with special attention to those techniques applicable to bedded salt. The techniques are grouped into sections as follows: tectonic environment, state of stress, subsurface structures, fractures, stress changes, deformation, thermal properties, fluid transport properties, and other approaches. Several areas that merit further research and developments are identified. These areas are: in situ thermal measurement techniques, fracture detection and characterization, in situ stress measurements, and creep behavior. The available instrumentations should generally be improved to have better resolution and accuracy, enhanced instrument survivability, and reliability for extended time periods in a hostile environment.
Coupled processes in single fractures, double fractures and fractured porous media

International Nuclear Information System (INIS)

Tsang, C.F.

1986-12-01

The emplacement of a nuclear waste repository in a fractured porous medium provides a heat source of large dimensions over an extended period of time. It also creates a large cavity in the rock mass, changing significantly the stress field. Such major changes induce various coupled thermohydraulic, hydromechanic and hydrochemical transport processes in the environment around a nuclear waste repository. The present paper gives, first, a general overview of the coupled processes involving thermal, mechanical, hydrological and chemical effects. Then investigations of a number of specific coupled processes are described in the context of fluid flow and transport in a single fracture, two intersecting fractures and a fractured porous medium near a nuclear waste repository. The results are presented and discussed
Facial Fractures.

Science.gov (United States)

Ghosh, Rajarshi; Gopalkrishnan, Kulandaswamy

2018-06-01

The aim of this study is to retrospectively analyze the incidence of facial fractures along with age, gender predilection, etiology, commonest site, associated dental injuries, and any complications of patients operated in Craniofacial Unit of SDM College of Dental Sciences and Hospital. This retrospective study was conducted at the Department of OMFS, SDM College of Dental Sciences, Dharwad from January 2003 to December 2013. Data were recorded for the cause of injury, age and gender distribution, frequency and type of injury, localization and frequency of soft tissue injuries, dentoalveolar trauma, facial bone fractures, complications, concomitant injuries, and different treatment protocols.All the data were analyzed using statistical analysis that is chi-squared test. A total of 1146 patients reported at our unit with facial fractures during these 10 years. Males accounted for a higher frequency of facial fractures (88.8%). Mandible was the commonest bone to be fractured among all the facial bones (71.2%). Maxillary central incisors were the most common teeth to be injured (33.8%) and avulsion was the most common type of injury (44.6%). Commonest postoperative complication was plate infection (11%) leading to plate removal. Other injuries associated with facial fractures were rib fractures, head injuries, upper and lower limb fractures, etc., among these rib fractures were seen most frequently (21.6%). This study was performed to compare the different etiologic factors leading to diverse facial fracture patterns. By statistical analysis of this record the authors come to know about the relationship of facial fractures with gender, age, associated comorbidities, etc.

Chance Fracture Secondary to a Healed Kyphotic Compression Osteoporotic Fracture

Directory of Open Access Journals (Sweden)

Teh KK

2009-11-01

Full Text Available Chance fracture is an unstable vertebral fracture, which usually results from a high velocity injury. An elderly lady with a previously healed osteoporotic fracture of the T12 and L1 vertebra which resulted in a severe kyphotic deformity subsequently sustained a Chance fracture of the adjacent L2 vertebrae after a minor fall. The previously fracture left her with a deformity which resulted in significant sagittal imbalance therefore predisposing her to this fracture. This case highlights the importance of aggressive treatment of osteoporotic fractures in order to prevent significant sagittal imbalance from resultant (i.e. kyphotic deformity.
Hip Fracture

Science.gov (United States)

... hip fractures in people of all ages. In older adults, a hip fracture is most often a result of a fall from a standing height. In people with very weak bones, a hip fracture can occur simply by standing on the leg and twisting. Risk factors The rate of hip fractures increases substantially with ...
Ankle fractures have features of an osteoporotic fracture.

Science.gov (United States)

Lee, K M; Chung, C Y; Kwon, S S; Won, S H; Lee, S Y; Chung, M K; Park, M S

2013-11-01

We report the bone attenuation of ankle joint measured on computed tomography (CT) and the cause of injury in patients with ankle fractures. The results showed age- and gender-dependent low bone attenuation and low-energy trauma in elderly females, which suggest the osteoporotic features of ankle fractures. This study was performed to investigate the osteoporotic features of ankle fracture in terms of bone attenuation and cause of injury. One hundred ninety-four patients (mean age 51.0 years, standard deviation 15.8 years; 98 males and 96 females) with ankle fracture were included. All patients underwent CT examination, and causes of injury (high/low-energy trauma) were recorded. Mean bone attenuations of the talus, medial malleolus, lateral malleolus, and distal tibial metaphysis were measured on CT images. Patients were divided into younger age (fractures than the younger age group. With increasing age, bone attenuations tended to decrease and the difference of bone attenuation between the genders tended to increase in the talus, medial malleolus, lateral malleolus, and distal tibial metaphysis. Ankle fracture had features of osteoporotic fracture that is characterized by age- and gender-dependent low bone attenuation. Ankle fracture should not be excluded from the clinical and research interest as well as from the benefit of osteoporosis management.
Groundwater modelling for fractured and porous media: HYDROCOIN Level 1

International Nuclear Information System (INIS)

Noy, D.J.

1986-01-01

The report describes work carried out as part of the 'Hydrocoin' project to verify some of the models used by the British Geological Survey on its radioactive waste disposal programme. The author's work on Hydrocoin Level 1 concerned groundwater modelling for fractured and porous media. The overall conclusions arising from the work were: a) pressure fields in saturated media can be reliably calculated by existing programmes, b) three techniques for deriving the flow fields are described, and c) severe practical limitations exist as to the ability of current programs to model variably saturated conditions over moderate distances. (U.K.)
Seismic attribute analysis and its application to mapping folds and fractures

Science.gov (United States)

Mai, Ha Thanh

Geometric attributes such as coherence and curvature have been very successful in delineating faults in sedimentary basins. While not a common exploration objective, fractured and faulted basement forms important reservoirs in Venezuela, USA (Southern California), Brazil, Libya, Algeria, Egypt, Russia, and Vietnam (Landes, 1960; Canh, 2008). Because of the absence of stratified, coherent reflectors, illumination of basement faults is more problematic than illumination of faults within the sedimentary column. In order to address these problems, it is important to carefully analyze alternative forms of the 3D seismic data, which in this dissertation will be primarily combinations of one or more seismic attributes, and interpret them within the context of an appropriate structural deformation model. For that purpose, in this research, I concentrate on analyzing structural dip and azimuth, amplitude energy gradients, and a large family of attributes based on curvature to better illuminate fracture 'sweet spots' and estimate their density and orientation. I develop and calibrate these attribute and interpretation workflows through application to a complexly folded and faulted, but otherwise typical, geologic target in the Chicontepec Basin of Mexico. I then apply this calibrated workflow to better characterize faults and build fracture models in the granite basement of the Cuu Long Basin, Vietnam, and the granite and rhyolite-metarhyolite basement of Osage County, Oklahoma, USA. In the Cuu Long granite basement, it forms an important unconventional reservoir. In Osage County, we suspect basement control of overlying fractures in the Mississippian chat deposits.
A Rare Entity: Bilateral First Rib Fractures Accompanying Bilateral Scapular Fractures

OpenAIRE

Gulbahar, Gultekin; Kaplan, Tevfik; Turker, Hasan Bozkurt; Gundogdu, Ahmet Gokhan; Han, Serdar

2015-01-01

First rib fractures are scarce due to their well-protected anatomic locations. Bilateral first rib fractures accompanying bilateral scapular fractures are very rare, although they may be together with scapular and clavicular fractures. According to our knowledge, no case of bilateral first rib fractures accompanying bilateral scapular fractures has been reported, so we herein discussed the diagnosis, treatment, and complications of bone fractures due to thoracic trauma in bias of this rare en...
A Rare Entity: Bilateral First Rib Fractures Accompanying Bilateral Scapular Fractures.

Science.gov (United States)

Gulbahar, Gultekin; Kaplan, Tevfik; Turker, Hasan Bozkurt; Gundogdu, Ahmet Gokhan; Han, Serdar

2015-01-01

First rib fractures are scarce due to their well-protected anatomic locations. Bilateral first rib fractures accompanying bilateral scapular fractures are very rare, although they may be together with scapular and clavicular fractures. According to our knowledge, no case of bilateral first rib fractures accompanying bilateral scapular fractures has been reported, so we herein discussed the diagnosis, treatment, and complications of bone fractures due to thoracic trauma in bias of this rare entity.
Statistical model of fractures and deformations zones for Forsmark. Preliminary site description Forsmark area - version 1.2

Energy Technology Data Exchange (ETDEWEB)

La Pointe, Paul R. [Golder Associate Inc., Redmond, WA (United States); Olofsson, Isabelle; Hermanson, Jan [Golder Associates AB, Uppsala (Sweden)

2005-04-01

Compared to version 1.1, a much larger amount of data especially from boreholes is available. Both one-hole interpretation and Boremap indicate the presence of high and low fracture intensity intervals in the rock mass. The depth and width of these intervals varies from borehole to borehole but these constant fracture intensity intervals are contiguous and present quite sharp transitions. There is not a consistent pattern of intervals of high fracture intensity at or near to the surface. In many cases, the intervals of highest fracture intensity are considerably below the surface. While some fractures may have occurred or been reactivated in response to surficial stress relief, surficial stress relief does not appear to be a significant explanatory variable for the observed variations in fracture intensity. Data from the high fracture intensity intervals were extracted and statistical analyses were conducted in order to identify common geological factors. Stereoplots of fracture orientation versus depth for the different fracture intensity intervals were also produced for each borehole. Moreover percussion borehole data were analysed in order to identify the persistence of these intervals throughout the model volume. The main conclusions of these analyses are the following: The fracture intensity is conditioned by the rock domain, but inside a rock domain intervals of high and low fracture intensity are identified. The intervals of high fracture intensity almost always correspond to intervals with distinct fracture orientations (whether a set, most often the NW sub-vertical set, is highly dominant, or some orientation sets are missing). These high fracture intensity intervals are positively correlated to the presence of first and second generation minerals (epidote, calcite). No clear correlation for these fracture intensity intervals has been identified between holes. Based on these results the fracture frequency has been calculated in each rock domain for the
Statistical model of fractures and deformations zones for Forsmark. Preliminary site description Forsmark area - version 1.2

International Nuclear Information System (INIS)

La Pointe, Paul R.; Olofsson, Isabelle; Hermanson, Jan

2005-04-01

Compared to version 1.1, a much larger amount of data especially from boreholes is available. Both one-hole interpretation and Boremap indicate the presence of high and low fracture intensity intervals in the rock mass. The depth and width of these intervals varies from borehole to borehole but these constant fracture intensity intervals are contiguous and present quite sharp transitions. There is not a consistent pattern of intervals of high fracture intensity at or near to the surface. In many cases, the intervals of highest fracture intensity are considerably below the surface. While some fractures may have occurred or been reactivated in response to surficial stress relief, surficial stress relief does not appear to be a significant explanatory variable for the observed variations in fracture intensity. Data from the high fracture intensity intervals were extracted and statistical analyses were conducted in order to identify common geological factors. Stereoplots of fracture orientation versus depth for the different fracture intensity intervals were also produced for each borehole. Moreover percussion borehole data were analysed in order to identify the persistence of these intervals throughout the model volume. The main conclusions of these analyses are the following: The fracture intensity is conditioned by the rock domain, but inside a rock domain intervals of high and low fracture intensity are identified. The intervals of high fracture intensity almost always correspond to intervals with distinct fracture orientations (whether a set, most often the NW sub-vertical set, is highly dominant, or some orientation sets are missing). These high fracture intensity intervals are positively correlated to the presence of first and second generation minerals (epidote, calcite). No clear correlation for these fracture intensity intervals has been identified between holes. Based on these results the fracture frequency has been calculated in each rock domain for the
Dawsonite and other carbonate veins in the Cretaceous Izumi Group, SW Japan: a natural support for fracture self-sealing in mud-stone cap-rock in CGS?

Energy Technology Data Exchange (ETDEWEB)

Okuyama, Yasuko; Funatsu, Takahiro; Fujii, Takashi [Institute for Geo-Resources and environment, GSJ, AISI, 1-1-1 Higashi, Central 7, Tsukuba, ibaraki 305-8567 (Japan); Take, Shuji [Kishiwada Nature Club, c/o Kishiwada City Natural History Museum, Sakai-Machi 5-6, Kishiwada, Osaka 596-0072 (Japan)

2013-07-01

Dawsonite-bearing carbonate veins are abundant in a compact mud-stone layer of the lower part of the Izumi Group, SW Japan. The mode of occurrence of the veins probably indicates fracturing and mineral sealing associated with upwelling of CO{sub 2}-rich fluid evolved in the reservoir beneath. The carbonate veins studied here can be a natural support to fracturing and healing of mud-stone cap-rock in the CO{sub 2} geological storage. (authors)
Electricity generation from enhanced geothermal systems by oilfield produced water circulating through reservoir stimulated by staged fracturing technology for horizontal wells: A case study in Xujiaweizi area in Daqing Oilfield, China

International Nuclear Information System (INIS)

Zhang, Yan-Jun; Li, Zheng-Wei; Guo, Liang-Liang; Gao, Ping; Jin, Xian-Peng; Xu, Tian-Fu

2014-01-01

In this paper, the feasibility of generating electricity from EGS (enhanced geothermal systems) by oilfield produced water circulating through reservoir stimulated by staged fracturing technology for horizontal wells is investigated based on the geological data of Xujiaweizi area, located in the Daqing Oilfield, northeast China. HDR (hot dry rock) resource potential assessment is carried out by using volumetric method. Reservoir stimulation is numerically simulated based on the geological data of well YS-1 and field fracturing experience in this region. Geometric dimensions and flow conductivity of the resulting fracture are imported into the hydro-thermal model to calculate the electricity generation potential of the proposed EGS power plant. An EGS design scheme is proposed based on the simulation results. The system is also evaluated from the economic and environmental aspects. The results indicate that HDR resource in Xujiaweizi area is of great potential for development. Through the staged fracturing technology for horizontal wells, electricity generation power of the proposed EGS project can roughly meet the commercial standard. For 20 years of continuous production, power generation from the proposed EGS power plant is economic feasible. Meanwhile, significant reductions in greenhouse gas emissions can be achieved. - Highlights: • Staged fracturing technology for horizontal well is used in HDR (hot dry rock) development. • Fracturing simulations and heat production simulations are combined. • A 3 MW power plant is designed in Xujiaweizi based on the simulation results
Radar Mapping of Fractures and Fluids in Hydrocarbon Reservoirs

Science.gov (United States)

Stolarczyk, L. G.; Wattley, G. G.; Caffey, T. W.

2001-05-01

A stepped-frequency radar has been developed for mapping of fractures and fluids within 20 meters of the wellbore. The operating range has been achieved by using a radiating magnetic dipole operating in the low- and medium-frequency bands. Jim Wait has shown that the electromagnetic (EM) wave impedance in an electrically conductive media is largely imaginary, enabling energy to be stored in the near field instead of dissipated, as in the case for an electric dipole. This fact, combined with the low attenuation rate of a low-frequency band EM wave, enables radiation to penetrate deeply into the geology surrounding the wellbore. The radiation pattern features a vertical electric field for optimum electric current induction into vertical fractures. Current is also induced in sedimentary rock creating secondary waves that propagate back to the wellbore. The radiation pattern is electrically driven in azimuth around the wellbore. The receiving antenna is located in the null field of the radiating antenna so that the primary wave is below the thermal noise of the receiver input. By stepping the frequency through the low- and medium-frequency bands, the depth of investigation is varied, and enables electrical conductivity profiling away from the wellbore. Interpretation software has been developed for reconstructive imaging in dipping sedimentary layers. Because electrical conductivity can be related to oil/water saturation, both fractures and fluids can be mapped. Modeling suggests that swarms of fractures can be imaged and fluid type determined. This information will be useful in smart fracking and sealing. Conductivity tomography images will indicate bed dip, oil/water saturation, and map fluids. This paper will provide an overview of the technology development program.
Rock types and ductile structures on a rock domain basis, and fracture orientation and mineralogy on a deformation zone basis. Preliminary site description. Forsmark area - version 1.2

Energy Technology Data Exchange (ETDEWEB)

Stephens, Michael [Geological Survey of Sweden, Uppsala (Sweden); Forssberg, Ola [Golder Associates AB, Uppsala (Sweden)

2006-09-15

This report presents the results of the analysis of base geological data in order to establish the dominant rock type, the subordinate rock types and the orientation of ductile mineral fabrics within each rock domain included in the regional geological model, version 1.2. An assessment of the degree of homogeneity of each domain is also provided. The analytical work has utilised the presentation of data in the form of histograms and stereographic projections. Fisher means and K values or best-fit great circles and corresponding pole values have been calculated for the ductile structural data. These values have been used in the geometric modelling of rock domains in the regional model, version 1.2. Furthermore, all analytical results have been used in the assignment of properties to rock domains in this model. A second analytical component reported here addresses the orientation and mineralogy of fractures in the deterministic deformation zones that are included in the regional geological model, version 1.2. The analytical work has once again utilised the presentation of data in the form of histograms and stereographic projections. Fisher means and K values are presented for the orientation of fracture sets in the deterministic deformation zones that have been identified with the help of new borehole data. The frequencies of occurrence of different minerals along the fractures in these deformation zones as well as the orientation of fractures in the zones, along which different minerals occur, are also presented. The results of the analyses have been used in the establishment of a conceptual structural model for the Forsmark site and in the assignment of properties to deterministic deformation zones in model version 1.2.
Past and future fracturing in AECL Research areas in the superior province of the Canadian Precambrian Shield, with emphasis on the Lac du Bonnet Batholith

Energy Technology Data Exchange (ETDEWEB)

Brown, A; Everitt, R A; Martin, C D; Davison, C C [Atomic Energy of Canada Ltd., Pinawa, MB (Canada). Whiteshell Labs.

1995-10-01

The likelihood that future fracturing, arising from geologic causes, could occur in the vicinity of a nuclear fuel waste repository in plutonic rock of the Canadian Precambrian Shield, is examined. The report discusses the possible causes of fracturing (both past and future) in Shield rocks. The report then examines case histories of fracture formation in Precambrian plutonic rocks in AECL`s Research Areas, especially the history of the Lac du Bonnet Batholith, in the Whiteshell Area, Manitoba. Initially, fractures can be introduced into intrusive plutonic rocks during crystallization and cooling of an intrusive magma. These fractures are found at all size scales; as late residual magma dyking, hydraulic fracturing by retrograde boiling off of hydrothermal fluids, and, in some cases, through local differential cooling. Subsequent fracturing is largely caused by changes in environmental temperature and stress field, rather than by alteration of the material behaviour of the rock. Pluton emplacement during orogeny is commonly accompanied by uplift and erosional exhumation, altering both the tectonic and the lithostatic stresses, the rock temperature gradient and the pore fluid characteristics.
Past and future fracturing in AECL Research areas in the superior province of the Canadian Precambrian Shield, with emphasis on the Lac du Bonnet Batholith

International Nuclear Information System (INIS)

Brown, A.; Everitt, R.A.; Martin, C.D.; Davison, C.C.

1995-10-01

The likelihood that future fracturing, arising from geologic causes, could occur in the vicinity of a nuclear fuel waste repository in plutonic rock of the Canadian Precambrian Shield, is examined. The report discusses the possible causes of fracturing (both past and future) in Shield rocks. The report then examines case histories of fracture formation in Precambrian plutonic rocks in AECL's Research Areas, especially the history of the Lac du Bonnet Batholith, in the Whiteshell Area, Manitoba. Initially, fractures can be introduced into intrusive plutonic rocks during crystallization and cooling of an intrusive magma. These fractures are found at all size scales; as late residual magma dyking, hydraulic fracturing by retrograde boiling off of hydrothermal fluids, and, in some cases, through local differential cooling. Subsequent fracturing is largely caused by changes in environmental temperature and stress field, rather than by alteration of the material behaviour of the rock. Pluton emplacement during orogeny is commonly accompanied by uplift and erosional exhumation, altering both the tectonic and the lithostatic stresses, the rock temperature gradient and the pore fluid characteristics
Relationships between fractures

Science.gov (United States)

Peacock, D. C. P.; Sanderson, D. J.; Rotevatn, A.

2018-01-01

Fracture systems comprise many fractures that may be grouped into sets based on their orientation, type and relative age. The fractures are often arranged in a network that involves fracture branches that interact with one another. Interacting fractures are termed geometrically coupled when they share an intersection line and/or kinematically coupled when the displacements, stresses and strains of one fracture influences those of the other. Fracture interactions are characterised in terms of the following. 1) Fracture type: for example, whether they have opening (e.g., joints, veins, dykes), closing (stylolites, compaction bands), shearing (e.g., faults, deformation bands) or mixed-mode displacements. 2) Geometry (e.g., relative orientations) and topology (the arrangement of the fractures, including their connectivity). 3) Chronology: the relative ages of the fractures. 4) Kinematics: the displacement distributions of the interacting fractures. It is also suggested that interaction can be characterised in terms of mechanics, e.g., the effects of the interaction on the stress field. It is insufficient to describe only the components of a fracture network, with fuller understanding coming from determining the interactions between the different components of the network.
Dating methods and geochronology of fractures and movements in bedrock: a review

Energy Technology Data Exchange (ETDEWEB)

Tullborg, E.L. [Terralogica AB, Graabo (Sweden); Larson, Sven Aake [Goeteborgs Univ. (Sweden); Morad, S. [Uppsala Univ. (Sweden)

2001-06-01

Constraining the absolute and relative ages of crustal movements is of fundamental importance in evaluating the potentials of a site as a repository for spent radioactive fuel. In this report a review summary of up to date absolute and relative dating methods is presented with specific attention to those methods most amenable for dating of fractures. A review of major fracture-and shear zones in the Swedish part of the Baltic Shield is also given. Since the shield has suffered a long and complicated history, geo-chronologists are faced with the problem of reactivated zones when attempting to date these. It is important to get structural control in order to make the choice of dating method since different methods may give answer to completely different questions. An integration of all geological background data is necessary in order to make the proper chose to fit the raised question.
Dating methods and geochronology of fractures and movements in bedrock: a review

International Nuclear Information System (INIS)

Tullborg, E.L.; Larson, Sven Aake; Morad, S.

2001-06-01

Constraining the absolute and relative ages of crustal movements is of fundamental importance in evaluating the potentials of a site as a repository for spent radioactive fuel. In this report a review summary of up to date absolute and relative dating methods is presented with specific attention to those methods most amenable for dating of fractures. A review of major fracture-and shear zones in the Swedish part of the Baltic Shield is also given. Since the shield has suffered a long and complicated history, geo-chronologists are faced with the problem of reactivated zones when attempting to date these. It is important to get structural control in order to make the choice of dating method since different methods may give answer to completely different questions. An integration of all geological background data is necessary in order to make the proper chose to fit the raised question
A Rare Entity: Bilateral First Rib Fractures Accompanying Bilateral Scapular Fractures

Directory of Open Access Journals (Sweden)

Gultekin Gulbahar

2015-01-01

Full Text Available First rib fractures are scarce due to their well-protected anatomic locations. Bilateral first rib fractures accompanying bilateral scapular fractures are very rare, although they may be together with scapular and clavicular fractures. According to our knowledge, no case of bilateral first rib fractures accompanying bilateral scapular fractures has been reported, so we herein discussed the diagnosis, treatment, and complications of bone fractures due to thoracic trauma in bias of this rare entity.
Proximal femoral fractures.

Science.gov (United States)

Webb, Lawrence X

2002-01-01

Fractures of the proximal femur include fractures of the head, neck, intertrochanteric, and subtrochanteric regions. Head fractures commonly accompany dislocations. Neck fractures and intertrochanteric fractures occur with greatest frequency in elderly patients with a low bone mineral density and are produced by low-energy mechanisms. Subtrochanteric fractures occur in a predominantly strong cortical osseous region which is exposed to large compressive stresses. Implants used to address these fractures must be able to accommodate significant loads while the fractures consolidate. Complications secondary to these injuries produce significant morbidity and include infection, nonunion, malunion, decubitus ulcers, fat emboli, deep venous thrombosis, pulmonary embolus, pneumonia, myocardial infarction, stroke, and death.

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