WorldWideScience

Sample records for natural fracture connectivity

  1. Dependence of Upscaled Effective Permeability Upon Fracture Orientation and Connectivity in Naturally Fractured Reservoirs

    Science.gov (United States)

    Gulamali, M. Y.; Matthai, S. K.

    2007-12-01

    Although geologically informed models of hydrocarbon reservoirs are available at relatively high resolution, i.e. the pore scale, numerical reservoir simulators require descriptions at a larger scale, i.e. the grid-block scale, in order to produce exploitable information about the reservoir. This process, known as upscaling, is especially complicated, yet relevant, in the case of naturally fractured reservoirs which contain over half of the global hydrocarbon reserves, and are extremely heterogeneous, exhibiting complicated multiphase flow behaviour at all scales. In this work we study the effect of discrete fracture networks upon the upscaled effective permeability of the system, using a sophisticated numerical pressure-solver method based upon a finite element-finite volume scheme. We begin by examining an idealized scenario consisting of a single discrete fracture in two dimensions, and show how the upscaled effective permeability is a non-additive property. This investigation is extended to real fracture networks using outcrop data, where we find the upscaled effective permeability to be dependent upon the orientation and connectivity of the fracture network. Finally, we present our ideas for examining the influence of three dimensional fractures upon upscaled reservoir parameters.

  2. Effect of Natural Fractures on Hydraulic Fracturing

    Science.gov (United States)

    Ben, Y.; Wang, Y.; Shi, G.

    2012-12-01

    Hydraulic Fracturing has been used successfully in the oil and gas industry to enhance oil and gas production in the past few decades. Recent years have seen the great development of tight gas, coal bed methane and shale gas. Natural fractures are believed to play an important role in the hydraulic fracturing of such formations. Whether natural fractures can benefit the fracture propagation and enhance final production needs to be studied. Various methods have been used to study the effect of natural fractures on hydraulic fracturing. Discontinuous Deformation Analysis (DDA) is a numerical method which belongs to the family of discrete element methods. In this paper, DDA is coupled with a fluid pipe network model to simulate the pressure response in the formation during hydraulic fracturing. The focus is to study the effect of natural fractures on hydraulic fracturing. In particular, the effect of rock joint properties, joint orientations and rock properties on fracture initiation and propagation will be analyzed. The result shows that DDA is a promising tool to study such complex behavior of rocks. Finally, the advantages of disadvantages of our current model and future research directions will be discussed.

  3. Natural fracture characterization using passive seismic illumination

    Energy Technology Data Exchange (ETDEWEB)

    Nihei, K.T.

    2003-01-08

    The presence of natural fractures in reservoir rock can significantly enhance gas production, especially in tight gas formations. Any general knowledge of the existence, location, orientation, spatial density, and connectivity of natural fractures, as well as general reservoir structure, that can be obtained prior to active seismic acquisition and drilling can be exploited to identify key areas for subsequent higher resolution active seismic imaging. Current practices for estimating fracture properties before the acquisition of surface seismic data are usually based on the assumed geology and tectonics of the region, and empirical or fracture mechanics-based relationships between stratigraphic curvature and fracturing. The objective of this research is to investigate the potential of multicomponent surface sensor arrays, and passive seismic sources in the form of local earthquakes to identify and characterize potential fractured gas reservoirs located near seismically active regions. To assess the feasibility of passive seismic fracture detection and characterization, we have developed numerical codes for modeling elastic wave propagation in reservoir structures containing multiple, finite-length fractures. This article describes our efforts to determine the conditions for favorable excitation of fracture converted waves, and to develop an imaging method that can be used to locate and characterize fractures using multicomponent, passive seismic data recorded on a surface array.

  4. Naturally Connecting the World

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ During China International Trade Fair for Home Textiles and Accessories held in Shanghai 2010(on Aug.25th the second day of the fair),Cotton Council International(CCI)hosted an exchange meeting targeted the COTTON USATM home textile licenses,taking"Naturally Connecting the World-Opportunities for Sourcing and Collaboration with Cotton-Made Home Textiles"as the theme of the meeting.CCI's representative institution in China invited the domestic famous home textile brands,enterprises and their customers to participate in the exchange which aims to introduce the current development trend of the global cotton textile industry through CCI,the powerful platform of communication.

  5. Mechanical stratigraphic controls on natural fracture spacing and penetration

    Science.gov (United States)

    McGinnis, Ronald N.; Ferrill, David A.; Morris, Alan P.; Smart, Kevin J.; Lehrmann, Daniel

    2017-02-01

    Fine-grained low permeability sedimentary rocks, such as shale and mudrock, have drawn attention as unconventional hydrocarbon reservoirs. Fracturing - both natural and induced - is extremely important for increasing permeability in otherwise low-permeability rock. We analyze natural extension fracture networks within a complete measured outcrop section of the Ernst Member of the Boquillas Formation in Big Bend National Park, west Texas. Results of bed-center, dip-parallel scanline surveys demonstrate nearly identical fracture strikes and slight variation in dip between mudrock, chalk, and limestone beds. Fracture spacing tends to increase proportional to bed thickness in limestone and chalk beds; however, dramatic differences in fracture spacing are observed in mudrock. A direct relationship is observed between fracture spacing/thickness ratio and rock competence. Vertical fracture penetrations measured from the middle of chalk and limestone beds generally extend to and often beyond bed boundaries into the vertically adjacent mudrock beds. In contrast, fractures in the mudrock beds rarely penetrate beyond the bed boundaries into the adjacent carbonate beds. Consequently, natural bed-perpendicular fracture connectivity through the mechanically layered sequence generally is poor. Fracture connectivity strongly influences permeability architecture, and fracture prediction should consider thin bed-scale control on fracture heights and the strong lithologic control on fracture spacing.

  6. Fracture Mechanics: Inspirations from Nature

    Directory of Open Access Journals (Sweden)

    David Taylor

    2014-10-01

    Full Text Available In Nature there are many examples of materials performing structural functions. Nature requires materials which are stiff and strong to provide support against various forces, including self-weight, the dynamic forces involved in movement, and external loads such as wind or the actions of a predator. These materials and structures have evolved over millions of years; the science of Biomimetics seeks to understand Nature and, as a result, to find inspiration for the creation of better engineering solutions. There has been relatively little fundamental research work in this area from a fracture mechanics point of view. Natural materials are quite brittle and, as a result, they have evolved several interesting strategies for preventing failure by crack propagation. Fatigue is also a major problem for many animals and plants. In this paper, several examples will be given of recent work in the Bioengineering Research Centre at Trinity College Dublin, investigating fracture and fatigue in such diverse materials as bamboo, the legs and wings of insects, and living cells.

  7. Simulation of Hydraulic and Natural Fracture Interaction Using a Coupled DFN-DEM Model

    Energy Technology Data Exchange (ETDEWEB)

    J. Zhou; H. Huang; M. Deo

    2016-03-01

    The presence of natural fractures will usually result in a complex fracture network due to the interactions between hydraulic and natural fracture. The reactivation of natural fractures can generally provide additional flow paths from formation to wellbore which play a crucial role in improving the hydrocarbon recovery in these ultra-low permeability reservoir. Thus, accurate description of the geometry of discrete fractures and bedding is highly desired for accurate flow and production predictions. Compared to conventional continuum models that implicitly represent the discrete feature, Discrete Fracture Network (DFN) models could realistically model the connectivity of discontinuities at both reservoir scale and well scale. In this work, a new hybrid numerical model that couples Discrete Fracture Network (DFN) and Dual-Lattice Discrete Element Method (DL-DEM) is proposed to investigate the interaction between hydraulic fracture and natural fractures. Based on the proposed model, the effects of natural fracture orientation, density and injection properties on hydraulic-natural fractures interaction are investigated.

  8. Tests on impact effect of partial fracture at steel frame connections

    Institute of Scientific and Technical Information of China (English)

    Yiyi CHEN; Ruoning BIAN; Fangfang LIAO

    2008-01-01

    Impact effect of sudden fracture at steel frame connections under severe earthquake or other extreme loads is presented in this paper. The relation of impulse caused by structural fracture to the release of inner force at the cracked location, the magnitude of the response to impact on the basis of one degree of freedom model, and the ratio of the peak value of response to natural period of the system are investigated. Two types of fracture tests were designed and carried out both on uniaxial steel bar tensioned and moment resistant steel frame model. It is proven that the response during the fracture process can be measured quite well using high-frequency data proces-sing system. It is also revealed that the instant fracture of structural connection is characterized by progressive and partial fracture. Numerical evaluation of the impact effect of connection fracture is carried out.

  9. Fractal modeling of natural fracture networks

    Energy Technology Data Exchange (ETDEWEB)

    Ferer, M.; Dean, B.; Mick, C.

    1995-06-01

    West Virginia University will implement procedures for a fractal analysis of fractures in reservoirs. This procedure will be applied to fracture networks in outcrops and to fractures intersecting horizontal boreholes. The parameters resulting from this analysis will be used to generate synthetic fracture networks with the same fractal characteristics as the real networks. Recovery from naturally fractured, tight-gas reservoirs is controlled by the fracture network. Reliable characterization of the actual fracture network in the reservoir is severely limited. The location and orientation of fractures intersecting the borehole can be determined, but the length of these fractures cannot be unambiguously determined. Because of the lack of detailed information about the actual fracture network, modeling methods must represent the porosity and permeability associated with the fracture network, as accurately as possible with very little a priori information. In the sections following, the authors will (1) present fractal analysis of the MWX site, using the box-counting procedure; (2) review evidence testing the fractal nature of fracture distributions and discuss the advantages of using the fractal analysis over a stochastic analysis; and (3) present an efficient algorithm for producing a self-similar fracture networks which mimic the real MWX outcrop fracture network.

  10. Natural connections given by general linear and classical connections

    OpenAIRE

    Janyška, Josef

    2004-01-01

    We assume a vector bundle $p: E\\to M$ with a general linear connection $K$ and a classical linear connection $\\Lam$ on $M$. We prove that all classical linear connections on the total space $E$ naturally given by $(\\Lam, K)$ form a 15-parameter family. Further we prove that all connections on $J^1 E$ naturally given by $(\\Lam, K)$ form a 14-parameter family. Both families of connections are described geometrically.

  11. A new approach for effectively determining fracture network connections in fractured rocks using R tree indexing

    Institute of Scientific and Technical Information of China (English)

    LIU Hua-mei; WANG Ming-yu; SONG Xian-feng

    2011-01-01

    Determinations of fracture network connections would help the investigators remove those “meaningless” no-flow-passing fractures,providing an updated and more effective fracture network that could considerably improve the computation efficiency in the pertinent numerical simulations of fluid flow and solute transport.The effective algorithms with higher computational efficiency are needed to accomplish this task in large-scale fractured rock masses.A new approach using R tree indexing was proposed for determining fracture connection in 3D stochastically distributed fracture network.By comparing with the traditional exhaustion algorithm,it was observed that from the simulation results,this approach was much more effective; and the more the fractures were investigated,the more obvious the advantages of the approach were.Furthermore,it was indicated that the runtime used for creating the R tree indexing has a major part in the total of the runtime used for calculating Minimum Bounding Rectangles(MBRs),creating the R tree indexing,precisely finding out fracture intersections,and identifying flow paths,which are four important steps to determine fracture connections.This proposed approach for the determination of fracture connections in three-dimensional fractured rocks are expected to provide efficient preprocessing and critical database for practically accomplishing numerical computation of fluid flow and solute transport in large-scale fractured rock masses.

  12. Periodic Hydraulic Testing for Discerning Fracture Network Connections

    Science.gov (United States)

    Becker, M.; Le Borgne, T.; Bour, O.; Guihéneuf, N.; Cole, M.

    2015-12-01

    Discrete fracture network (DFN) models often predict highly variable hydraulic connections between injection and pumping wells used for enhanced oil recovery, geothermal energy extraction, and groundwater remediation. Such connections can be difficult to verify in fractured rock systems because standard pumping or pulse interference tests interrogate too large a volume to pinpoint specific connections. Three field examples are presented in which periodic hydraulic tests were used to obtain information about hydraulic connectivity in fractured bedrock. The first site, a sandstone in New York State, involves only a single fracture at a scale of about 10 m. The second site, a granite in Brittany, France, involves a fracture network at about the same scale. The third site, a granite/schist in the U.S. State of New Hampshire, involves a complex network at scale of 30-60 m. In each case periodic testing provided an enhanced view of hydraulic connectivity over previous constant rate tests. Periodic testing is particularly adept at measuring hydraulic diffusivity, which is a more effective parameter than permeability for identify the complexity of flow pathways between measurement locations. Periodic tests were also conducted at multiple frequencies which provides a range in the radius of hydraulic penetration away from the oscillating well. By varying the radius of penetration, we attempt to interrogate the structure of the fracture network. Periodic tests, therefore, may be uniquely suited for verifying and/or calibrating DFN models.

  13. Local Natural Connectivity in Complex Networks

    Institute of Scientific and Technical Information of China (English)

    SHANG Yi-Lun

    2011-01-01

    @@ In network theory, a complex network represents a system whose evolving structure and dynamic behavior contribute to its robustness.The natural connectivity is recently proposed as a spectral measure to characterize the robustness of complex networks.We decompose the natural connectivity of a network as local natural connectivity of its connected components and quantify their contributions to the network robustness.In addition, we compare the natural connectivity of a network with that of an induced subgraph of it based on interlacing theorems.As an application, we derive an inequality for eigenvalues of ErdSs-Renyi random graphs.%In network theory, a complex network represents a system whose evolving structure and dynamic behavior contribute to its robustness. The natural connectivity is recently proposed as a spectral measure to characterize the robustness of complex networks. We decompose the natural connectivity of a network as local naturai connectivity of its connected components and quantify their contributions to the network robustness. In addition, we compare the naturai connectivity of a network with that of an induced subgraph of it based on interlacing theorems. As an application, we derive an inequality for eigenvalues of Erdos-Renyi random graphs.

  14. Elders' Lifelong Connection with the Natural Environment

    Science.gov (United States)

    Carman, Jack

    2011-01-01

    Our interaction with nature does not end just because we age. People have a lifelong connection with the outdoor environment in varying degrees. For some, this participation may be subtle by simply watching others interact with the outdoor environment. For others, there is a deeper connection with nature through gardening, birding, exercise,…

  15. Elders' Lifelong Connection with the Natural Environment

    Science.gov (United States)

    Carman, Jack

    2011-01-01

    Our interaction with nature does not end just because we age. People have a lifelong connection with the outdoor environment in varying degrees. For some, this participation may be subtle by simply watching others interact with the outdoor environment. For others, there is a deeper connection with nature through gardening, birding, exercise,…

  16. An Examination Of Fracture Splitting Parameters Of Crackable Connecting Rods

    Directory of Open Access Journals (Sweden)

    Zafer Özdemir

    2000-06-01

    Full Text Available Fracture splitting method is an innovative processing technique in the field of automobile engine connecting rod (con/rod manufacturing. Compared with traditional method, this technique has remarkable advantages. Manufacturing procedures, equipment and tools investment can be decreased and energy consumption reduced remarkably. Furthermore, product quality and bearing capability can also be improved. It provides a high quality, high accuracy and low cost route for producing connecting rods (con/rods. With the many advantages mentioned above, this method has attracted manufacturers attention and has been utilized in many types of con/rod manufacturing. In this article, the method and the advantages it provides, such as materials, notches for fracture splitting, fracture splitting conditions and fracture splitting equipment are discussed in detail. The paper describes an analysis of examination of fracture splitting parameters and optik-SEM fractography of C70S6 crackable connectıng rod. Force and velocity parameters are investigated. That uniform impact force distrubition starting from the starting notch causes brittle and cleavage failure mode is obtained as a result. This induces to decrease the toughness.

  17. Natural Connections on Riemannian Product Manifolds

    OpenAIRE

    Gribacheva, Dobrinka

    2011-01-01

    A Riemannian almost product manifold with integrable almost product structure is called a Riemannian product manifold. In the present paper the natural connections on such manifolds are studied, i.e. the linear connections preserving the almost product structure and the Riemannian metric.

  18. Science and Mathematics--A Natural Connection

    Science.gov (United States)

    Park Rogers, Meredith A.; Volkmann, Mark J.; Abell, Sandra K.

    2007-01-01

    Connections between science and mathematics seem natural. First, mathematics can be used in science to organize and analyze data in tables and graphs. Second, mathematics can help represent scientific phenomena and understand scientific concepts. Student learning should benefit when teachers make the connections between science and mathematics…

  19. Naturally fractured tight gas reservoir detection optimization

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-06-01

    Building upon the partitioning of the Greater Green River Basin (GGRB) that was conducted last quarter, the goal of the work this quarter has been to conclude evaluation of the Stratos well and the prototypical Green River Deep partition, and perform the fill resource evaluation of the Upper Cretaceous tight gas play, with the goal of defining target areas of enhanced natural fracturing. The work plan for the quarter of November 1-December 31, 1998 comprised four tasks: (1) Evaluation of the Green River Deep partition and the Stratos well and examination of potential opportunity for expanding the use of E and P technology to low permeability, naturally fractured gas reservoirs, (2) Gas field studies, and (3) Resource analysis of the balance of the partitions.

  20. Connections with nature and environmental behaviors.

    Science.gov (United States)

    Geng, Liuna; Xu, Jingke; Ye, Lijuan; Zhou, Wenjun; Zhou, Kexin

    2015-01-01

    The influence of environmental attitudes on environmental behaviors has long been discussed. However, few studies have addressed the foundation of such attitudes. In the present study, we explored primitive belief underlying environmental attitudes, i.e., connections with nature, and its relationship with pro-environmental behaviors. Specifically, we used scales, a computerized Implicit Association Test, and a situational simulation experiment to examine both explicit and implicit connections with nature, both deliberate and spontaneous environmental behaviors, and to find correlations between environmental connectedness and environmental behaviors. Results showed that explicit connectedness was positively correlated with deliberate environmental behaviors, while implicit connectedness was positively correlated with spontaneous environmental behaviors. Additionally, explicit and implicit connectedness was independent of each other. In conclusion, the current study confirms the positive role played by connections with nature in promoting environmental behavior, and accordingly suggests means to encourage pro-environmental behavior by enhancing people's connectedness to nature.

  1. Connection to Nature: Children's Affective Attitude toward Nature

    Science.gov (United States)

    Cheng, Judith Chen-Hsuan; Monroe, Martha C.

    2012-01-01

    A connection to nature index was developed and tested to measure children's affective attitude toward the natural environment. The index was employed through a survey that investigates students' attitude toward Lagoon Quest, a mandatory environmental education program for all fourth-grade, public school students in Brevard County, Florida. Factor…

  2. Connection to Nature: Children's Affective Attitude toward Nature

    Science.gov (United States)

    Cheng, Judith Chen-Hsuan; Monroe, Martha C.

    2012-01-01

    A connection to nature index was developed and tested to measure children's affective attitude toward the natural environment. The index was employed through a survey that investigates students' attitude toward Lagoon Quest, a mandatory environmental education program for all fourth-grade, public school students in Brevard County, Florida. Factor…

  3. A review of numerical simulation strategies for hydraulic fracturing, natural fracture reactivation and induced microseismicity prediction

    NARCIS (Netherlands)

    Shahid, A.S.A.; Fokker, P.A.; Rocca, V.

    2016-01-01

    Hydraulic fracturing, natural fracture reactivation and resulting induced microseismicity are interconnected phenomena involved in shale gas exploitation. Due to their multi-physics and their complexity, deep understanding of these phenomena as well as their mutual interaction require the adoption

  4. Naturally fractured tight gas reservoir detection optimization

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-11-30

    The work plan for October 1, 1997 to September 30, 1998 consisted of investigation of a number of topical areas. These topical areas were reported in four quarterly status reports, which were submitted to DOE earlier. These topical areas are reviewed in this volume. The topical areas covered during the year were: (1) Development of preliminary tests of a production method for determining areas of natural fracturing. Advanced Resources has demonstrated that such a relationship exists in the southern Piceance basin tight gas play. Natural fracture clusters are genetically related to stress concentrations (also called stress perturbations) associated with local deformation such a faulting. The mechanical explanation of this phenomenon is that deformation generally initiates at regions where the local stress field is elevated beyond the regional. (2) Regional structural and geologic analysis of the Greater Green River Basin (GGRB). Application of techniques developed and demonstrated during earlier phases of the project for sweet-spot delineation were demonstrated in a relatively new and underexplored play: tight gas from continuous-typeUpper Cretaceous reservoirs of the Greater Green River Basin (GGRB). The effort included data acquisition/processing, base map generation, geophysical and remote sensing analysis and the integration of these data and analyses. (3) Examination of the Table Rock field area in the northern Washakie Basin of the Greater Green River Basin. This effort was performed in support of Union Pacific Resources- and DOE-planned horizontal drilling efforts. The effort comprised acquisition of necessary seismic data and depth-conversion, mapping of major fault geometry, and analysis of displacement vectors, and the development of the natural fracture prediction. (4) Greater Green River Basin Partitioning. Building on fundamental fracture characterization work and prior work performed under this contract, namely structural analysis using satellite and

  5. Characterization of hydraulic fractures and reservoir properties of shale using natural tracers

    Science.gov (United States)

    Heath, J. E.; Gardner, P.; Kuhlman, K. L.; Malama, B.

    2013-12-01

    Hydraulic fracturing plays a major role in the economic production of hydrocarbon from shale. Current fracture characterization techniques are limited in diagnosing the transport properties of the fractures on the near wellbore scale to that of the entire stimulated reservoir volume. Microseismic reveals information on fracture geometries, but not transport properties. Production analysis (e.g., rate transient analysis using produced fluids) estimates fracture and reservoir flow characteristics, but often relies on simplified models in terms of fracture geometries and fluid storage and transport. We present the approach and potential benefits of incorporating natural tracers with production data analysis for fracture and reservoir characterization. Hydraulic fracturing releases omnipresent natural tracers that accumulate in low permeability rocks over geologic time (e.g., radiogenic 4He and 40Ar). Key reservoir characteristics govern the tracer release, which include: the number, connectivity, and geometry of fractures; the distribution of fracture-surface-area to matrix-block-volume; and the nature of hydrocarbon phases within the reservoir (e.g., methane dissolved in groundwater or present as a separate gas phase). We explore natural tracer systematics using numerical techniques under relevant shale-reservoir conditions. We evaluate the impact on natural tracer transport due to a variety of conceptual models of reservoir-transport properties and boundary conditions. Favorable attributes for analysis of natural tracers include the following: tracer concentrations start with a well-defined initial condition (i.e., equilibrium between matrix and any natural fractures); there is a large suite of tracers that cover a range of at least 7x in diffusion coefficients; and diffusive mass-transfer out of the matrix into hydraulic fractures will cause elemental and isotopic fractionation. Sandia National Laboratories is a multi-program laboratory managed and operated by

  6. Urban Bird Feeding: Connecting People with Nature.

    Directory of Open Access Journals (Sweden)

    Daniel T C Cox

    Full Text Available At a time of unprecedented biodiversity loss, researchers are increasingly recognizing the broad range of benefits provided to humankind by nature. However, as people live more urbanized lifestyles there is a progressive disengagement with the natural world that diminishes these benefits and discourages positive environmental behaviour. The provision of food for garden birds is an increasing global phenomenon, and provides a readily accessible way for people to counter this trend. Yet despite its popularity, quite why people feed birds remains poorly understood. We explore three loosely defined motivations behind bird feeding: that it provides psychological benefits, is due to a concern about bird welfare, and/or is due to a more general orientation towards nature. We quantitatively surveyed households from urban towns in southern England to explore attitudes and actions towards garden bird feeding. Each household scored three Likert statements relating to each of the three motivations. We found that people who fed birds regularly felt more relaxed and connected to nature when they watched garden birds, and perceived that bird feeding is beneficial for bird welfare while investing time in minimising associated risks. Finally, feeding birds may be an expression of a wider orientation towards nature. Overall, we found that the feelings of being relaxed and connected to nature were the strongest drivers. As urban expansion continues both to threaten species conservation and to change peoples' relationship with the natural world, feeding birds may provide an important tool for engaging people with nature to the benefit of both people and conservation.

  7. Subcritical growth of natural hydraulic fractures

    Science.gov (United States)

    Garagash, D.

    2014-12-01

    Joints are the most common example of brittle tensile failure in the crust. Their genesis at depth is linked to the natural hydraulic fracturing, which requires pore fluid pressure in excess of the minimum in situ stress [Pollard and Aidyn, JSG1988]. Depending on the geological setting, high pore pressure can result form burial compaction of interbedded strata, diagenesis, or tectonics. Common to these loading scenarios is slow build-up of pore pressure over a geological timescale, until conditions for initiation of crack growth are met on favorably oriented/sized flaws. The flaws can vary in size from grain-size cracks in igneous rocks to a fossil-size flaws in clastic rock, and once activated, are inferred to propagate mostly subcritically [Segall JGR 1984; Olson JGR 1993]. Despite many observational studies of natural hydraulic fractures, the modeling attempts appear to be few [Renshaw and Harvey JGR 1994]. Here, we use boundary integral formulation for the pore fluid inflow from the permeable rock into a propagating joint [Berchenko et al. IJRMMS 1997] coupled with the criteria for subcritical propagation assisted by the environmental effects of pore fluid at the crack tip to solve for the evolution of a penny-shape joint, which, in interbedded rock, may eventually evolve to short-blade geometry (propagation confined to a bed). Initial growth is exceedingly slow, paced by the stress corrosion reaction kinetics at the crack tip. During this stage the crack is fully-drained (i.e. the fluid pressure in the crack is equilibrated with the ambient pore pressure). This "slow" stage is followed by a rapid acceleration, driven by the increase of the mechanical stress intensity factor with the crack length, towards the terminal joint velocity. We provide an analytical expression for the latter as a function of the rock diffusivity, net pressure loading at the initiation (or flaw lengthscale), and parameters describing resistance to fracture growth. Due to a much slower

  8. Wellbore pressure response in naturally fractured reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, A.C. Jr.; Chang, W.; Raghavan, R.

    1983-01-01

    Recently a new flow regime has been identified for pressure drawdown or buildup data obtained from a well producing a naturally fractured reservoir. During the time period corresponding to this new flow regime, a semilog plot of pressure vs. time exhibits a semilog straight line with slope equal to m/2, where m is the slope of both the early and late time semilog straight lines predicted by the Warren and Root model. The identification of this intermediate time semilog straight line means that pressure data may exhibit as many as 3 semilog straight lines. A virtually complete analysis of well test pressure data is possible when the data exhibits 2 or more of the 3 possible straight lines. This work presents type curves which can be used to obtain a virtually complete analysis of pressure data when only one of the 3 semilog straight lines is reflected by the data. 13 references.

  9. Analysis of Fracturing Network Evolution Behaviors in Random Naturally Fractured Rock Blocks

    Science.gov (United States)

    Wang, Y.; Li, X.; Zhang, B.

    2016-11-01

    Shale gas has been discovered in the Upper Triassic Yanchang Formation, Ordos Basin, China. Due to the weak tectonic activities in the shale plays, core observations indicate abundant random non-tectonic micro-fractures in the producing shales. The role of micro-fractures in hydraulic fracturing for shale gas development is currently poorly understood yet potentially critical. In a series of scaled true triaxial laboratory experiments, we investigate the interaction of propagating fracturing network with natural fractures. The influence of dominating factors was studied and analyzed, with an emphasis on non-tectonic fracture density, injection rate, and stress ratio. A new index of P-SRV is proposed to evaluate the fracturing effectiveness. From the test results, three types of fracturing network geometry of radial random net-fractures, partly vertical fracture with random branches, and vertical main fracture with multiple branches were observed. It is suggested from qualitative and quantitative analysis that great micro-fracture density and injection rate tend to maximum the fracturing network; however, it tends to decrease the fracturing network with the increase in horizontal stress ratio. The function fitting results further proved that the injection rate has the most obvious influence on fracturing effectiveness.

  10. Discrete Fracture Network Modelling in a Naturally Fractured Carbonate Reservoir in the Jingbei Oilfield, China

    Directory of Open Access Journals (Sweden)

    Junling Fang

    2017-02-01

    Full Text Available This paper presents an integrated approach of discrete fracture network modelling for a naturally fractured buried-hill carbonate reservoir in the Jingbei Oilfield by using a 3D seismic survey, conventional well logs, and core data. The ant tracking attribute, extracted from 3D seismic data, is used to detect the faults and large-scale fractures. Fracture density and dip angle are evaluated by observing drilling cores of seven wells. The fracture density distribution in spatiality was predicted in four steps; firstly, the ant tracking attribute was extracted as a geophysical log; then an artificial neural network model was built by relating the fracture density with logs, e.g., acoustic, gamma ray, compensated neutron, density, and ant tracking; then 3D distribution models of acoustic, gamma ray, compensated neutron and density were generated by using a Gaussian random function simulation; and, finally, the fracture density distribution in 3D was predicted by using the generated artificial neural network model. Then, different methods were used to build the discrete fracture network model for different types of fractures of which large-scale fractures were modelled deterministically and small-scale fractures were modelled stochastically. The results show that the workflow presented in this study is effective for building discrete fracture network models for naturally fractured reservoirs.

  11. Natural thermal convection in fractured porous media

    Science.gov (United States)

    Adler, P. M.; Mezon, C.; Mourzenko, V.; Thovert, J. F.; Antoine, R.; Finizola, A.

    2015-12-01

    In the crust, fractures/faults can provide preferential pathways for fluid flow or act as barriers preventing the flow across these structures. In hydrothermal systems (usually found in fractured rock masses), these discontinuities may play a critical role at various scales, controlling fluid flows and heat transfer. The thermal convection is numerically computed in 3D fluid satured fractured porous media. Fractures are inserted as discrete objects, randomly distributed over a damaged volume, which is a fraction of the total volume. The fluid is assumed to satisfy Darcy's law in the fractures and in the porous medium with exchanges between them. All simulations were made for Rayleigh numbers (Ra) equilibrium with the medium), cubic boxes and closed-top conditions. Checks were performed on an unfractured porous medium and the convection cells do start for the theoretical value of Ra, namely 4p². 2D convection was verified up to Ra=800. The influence of parameters such as fracture aperture (or fracture transmissivity), fracture density and fracture length is studied. Moreover, these models are compared to porous media with the same macroscopic permeability. Preliminary results show that the non-uniqueness associated with initial conditions which makes possible either 2D or 3D convection in porous media (Schubert & Straus 1979) is no longer true for fractured porous media (at least for 50fracture density and fracture aperture on the Nusselt number (Nu) is highly Ra dependent. The effect of the damaged zone on Nu is roughly proportional to its size. All these models also allows us to determine for which range of fracture density the fractured porous medium is in good agreement with an unfractured porous medium of the same bulk permeability.

  12. A reservoir simulation approach for modeling of naturally fractured reservoirs

    Directory of Open Access Journals (Sweden)

    H. Mohammadi

    2012-12-01

    Full Text Available In this investigation, the Warren and Root model proposed for the simulation of naturally fractured reservoir was improved. A reservoir simulation approach was used to develop a 2D model of a synthetic oil reservoir. Main rock properties of each gridblock were defined for two different types of gridblocks called matrix and fracture gridblocks. These two gridblocks were different in porosity and permeability values which were higher for fracture gridblocks compared to the matrix gridblocks. This model was solved using the implicit finite difference method. Results showed an improvement in the Warren and Root model especially in region 2 of the semilog plot of pressure drop versus time, which indicated a linear transition zone with no inflection point as predicted by other investigators. Effects of fracture spacing, fracture permeability, fracture porosity, matrix permeability and matrix porosity on the behavior of a typical naturally fractured reservoir were also presented.

  13. Simulation of complex fracture networks influenced by natural fractures in shale gas reservoir

    Directory of Open Access Journals (Sweden)

    Zhao Jinzhou

    2014-10-01

    Full Text Available When hydraulic fractures intersect with natural fractures, the geometry and complexity of a fracture network are determined by the initiation and propagation pattern which is affected by a number of factors. Based on the fracture mechanics, the criterion for initiation and propagation of a fracture was introduced to analyze the tendency of a propagating angle and factors affecting propagating pressure. On this basis, a mathematic model with a complex fracture network was established to investigate how the fracture network form changes with different parameters, including rock mechanics, in-situ stress distribution, fracture properties, and frac treatment parameters. The solving process of this model was accelerated by classifying the calculation nodes on the extending direction of the fracture by equal pressure gradients, and solving the geometrical parameters prior to the iteration fitting flow distribution. With the initiation and propagation criterion as the bases for the propagation of branch fractures, this method decreased the iteration times through eliminating the fitting of the fracture length in conventional 3D fracture simulation. The simulation results indicated that the formation with abundant natural fractures and smaller in-situ stress difference is sufficient conditions for fracture network development. If the pressure in the hydraulic fractures can be kept at a high level by temporary sealing or diversion, the branch fractures will propagate further with minor curvature radius, thus enlarging the reservoir stimulation area. The simulated shape of fracture network can be well matched with the field microseismic mapping in data point range and distribution density, validating the accuracy of this model.

  14. Fracture network growth for prediction of fracture characteristics and connectivity in tight reservoir rocks

    NARCIS (Netherlands)

    Barnhoorn, A.; Cox, S.F.

    2012-01-01

    Fracturing experiments on very low-porosity dolomite rocks shows a difference in growth of fracture networks by stress-driven fracturing and fluid-driven fracturing. Stress-driven fracture growth, in the absence of fluid pressure, initially forms fractures randomly throughout the rocks followed by g

  15. 25 CFR 169.9 - Connection with natural objects.

    Science.gov (United States)

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Connection with natural objects. 169.9 Section 169.9... LANDS § 169.9 Connection with natural objects. When the distance to an established corner of the public survey is more than 6 miles, this connection will be made with a natural object or a permanent...

  16. A review of numerical simulation strategies for hydraulic fracturing, natural fracture reactivation and induced microseismicity prediction

    NARCIS (Netherlands)

    Shahid, A.S.A.; Fokker, P.A.; Rocca, V.

    2016-01-01

    Hydraulic fracturing, natural fracture reactivation and resulting induced microseismicity are interconnected phenomena involved in shale gas exploitation. Due to their multi-physics and their complexity, deep understanding of these phenomena as well as their mutual interaction require the adoption o

  17. SOLUTE TRANSPORT IN NATURAL FRACTURES BASED ON DIGITAL IMAGE TECHNOLOGY

    Institute of Scientific and Technical Information of China (English)

    TAN Ye-fei; ZHOU Zhi-fang; HUANG Yong

    2009-01-01

    A method of fracture boundary extraction was developed using the Gaussian template and Canny boundary detection on the basis of the collected digital images of natural fractures. The roughness and apertures of the fractures were briefly discussed from the point of view of digital image analysis. The extracted fractured image was translated into a lattice image which can be directly used in numerical simulation. The lattice Boltzmann and modified moment propagation mixed method was then applied to the simulation of solute transport in a natural single fracture, and this mixed method could take the advantages of the lattice Boltzmann method in dealing with complex physical boundaries. The obtained concentrations was fitted with the CXTFIT2.1 code and compared with the results obtained with the commercial software Feflow. The comparison indicates that the simulation using the mixed method is sound.

  18. Method for detecting moment connection fracture using high-frequency transients in recorded accelerations

    Science.gov (United States)

    Rodgers, J.E.; Elebi, M.

    2011-01-01

    The 1994 Northridge earthquake caused brittle fractures in steel moment frame building connections, despite causing little visible building damage in most cases. Future strong earthquakes are likely to cause similar damage to the many un-retrofitted pre-Northridge buildings in the western US and elsewhere. Without obvious permanent building deformation, costly intrusive inspections are currently the only way to determine if major fracture damage that compromises building safety has occurred. Building instrumentation has the potential to provide engineers and owners with timely information on fracture occurrence. Structural dynamics theory predicts and scale model experiments have demonstrated that sudden, large changes in structure properties caused by moment connection fractures will cause transient dynamic response. A method is proposed for detecting the building-wide level of connection fracture damage, based on observing high-frequency, fracture-induced transient dynamic responses in strong motion accelerograms. High-frequency transients are short (Elsevier B.V. All rights reserved.

  19. Development of Reservoir Characterization Techniques and Production Models for Exploiting Naturally Fractured Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Wiggins, Michael L.; Brown, Raymon L.; Civan, Frauk; Hughes, Richard G.

    2001-08-15

    Research continues on characterizing and modeling the behavior of naturally fractured reservoir systems. Work has progressed on developing techniques for estimating fracture properties from seismic and well log data, developing naturally fractured wellbore models, and developing a model to characterize the transfer of fluid from the matrix to the fracture system for use in the naturally fractured reservoir simulator.

  20. New pressure transient analysis methods for naturally fractured reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Serra, K.; Raghavan, R.; Reynolds, A.C.

    1983-10-01

    This paper presents new methods for analyzing pressure drawdown and buildup data obtained at wells producing naturally fractured reservoirs. The model used in this study assumes unsteady-state fluid transfer from the matrix system to the fracture system. A new flow regime is identified. The discovery of this flow regime explains field behavior that has been considered unusual. The probability of obtaining data reflecting this flow regime in a field test is higher than that of obtaining the classical responses given in the literature. The identification of this new flow regime provides methods for preparing a complete analysis of pressure data obtained from naturally fractured reservoirs. Applications to field data are discussed.

  1. New pressure transient analysis methods for naturally fractured reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Serra, K.; Raghavan, R.; Reynolds, A.C.

    1983-12-01

    This paper presents new methods for analyzing pressure drawdown and buildup data obtained at wells producing naturally fractured reservoirs. The model used in this study assumes unsteady-state fluid transfer from the matrix system to the fracture system. A new flow regime is identified. The discovery of this flow regime explains field behavior that has been considered unusual. The probability of obtaining data reflecting this flow regime in a field test is higher than that of obtaining the classical responses given in the literature. The identification of this new flow regime provides methods for preparing a complete analysis of pressure data obtained from naturally fractured reservoirs. Applications to field data are discussed.

  2. XFEM modeling of hydraulic fracture in porous rocks with natural fractures

    Science.gov (United States)

    Wang, Tao; Liu, ZhanLi; Zeng, QingLei; Gao, Yue; Zhuang, Zhuo

    2017-08-01

    Hydraulic fracture (HF) in porous rocks is a complex multi-physics coupling process which involves fluid flow, diffusion and solid deformation. In this paper, the extended finite element method (XFEM) coupling with Biot theory is developed to study the HF in permeable rocks with natural fractures (NFs). In the recent XFEM based computational HF models, the fluid flow in fractures and interstitials of the porous media are mostly solved separately, which brings difficulties in dealing with complex fracture morphology. In our new model the fluid flow is solved in a unified framework by considering the fractures as a kind of special porous media and introducing Poiseuille-type flow inside them instead of Darcy-type flow. The most advantage is that it is very convenient to deal with fluid flow inside the complex fracture network, which is important in shale gas extraction. The weak formulation for the new coupled model is derived based on virtual work principle, which includes the XFEM formulation for multiple fractures and fractures intersection in porous media and finite element formulation for the unified fluid flow. Then the plane strain Kristianovic-Geertsma-de Klerk (KGD) model and the fluid flow inside the fracture network are simulated to validate the accuracy and applicability of this method. The numerical results show that large injection rate, low rock permeability and isotropic in-situ stresses tend to lead to a more uniform and productive fracture network.

  3. 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.

  4. 3-D description of fracture surfaces and stress-sensitivity analysis for naturally fractured reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, S.Q.; Jioa, D.; Meng, Y.F.; Fan, Y.

    1997-08-01

    Three kinds of reservoir cores (limestone, sandstone, and shale with natural fractures) were used to study the effect of morphology of fracture surfaces on stress sensitivity. The cores, obtained from the reservoirs with depths of 2170 to 2300 m, have fractures which are mated on a large scale, but unmated on a fine scale. A specially designed photoelectric scanner with a computer was used to describe the topography of the fracture surfaces. Then, theoretical analysis of the fracture closure was carried out based on the fracture topography generated. The scanning results show that the asperity has almost normal distributions for all three types of samples. For the tested samples, the fracture closure predicted by the elastic-contact theory is different from the laboratory measurements because plastic deformation of the aspirates plays an important role under the testing range of normal stresses. In this work, the traditionally used elastic-contact theory has been modified to better predict the stress sensitivity of reservoir fractures. Analysis shows that the standard deviation of the probability density function of asperity distribution has a great effect on the fracture closure rate.

  5. 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.).

  6. A cubic matrix-fracture geometry model for radial tracer flow in naturally fractured reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Jetzabeth Ramirez-Sabag; Fernando Samaniego V.

    1992-01-01

    This study presents a general solution for the radial flow of tracers in naturally fractured reservoirs, with cubic blocks matrix-fracture geometry. Continuous and finite step injection of chemical and radioactive tracers are considered. The reservoir is treated as being composed of two regions: a mobile where dispersion and convection take place and a stagnant where only diffusion and adsorption are allowed. Radioactive decay is considered in both regions. The model of this study is thoroughly compared under proper simplified conditions to those previously presented in the literature. The coupled matrix to fracture solution in the Laplace space is numerically inverted by means of the Crump algorithm. A detailed validation of the model with respect to solutions previously presented and/or simplified physical conditions solutions (i.e., homogeneous case) or limit solutions (i.e., naturally fractured nearly homogeneous) was carried out. The influence of the three of the main dimensionless parameters that enter into the solution was carefully investigated. A comparison of results for three different naturally fractured systems, vertical fractures (linear flow), horizontal fractures (radial flow) and the cubic geometry model of this study, is presented.

  7. IUTAM Symposium on Fracture Phenomena in Nature and Technology

    CERN Document Server

    Carini, Angelo; Gei, Massimiliano; Salvadori, Alberto

    2014-01-01

    This book contains contributions presented at the IUTAM Symposium "Fracture Phenomena in Nature and Technology" held in Brescia, Italy, 1-5 July, 2012.The objective of the Symposium was fracture research, interpreted broadly to include new engineering and structural mechanics treatments of damage development and crack growth, and also large-scale failure processes as exemplified by earthquake or landslide failures, ice shelf break-up, and hydraulic fracturing (natural, or for resource extraction or CO2 sequestration), as well as small-scale rupture phenomena in materials physics including, e.g., inception of shear banding, void growth, adhesion and decohesion in contact and friction, crystal dislocation processes, and atomic/electronic scale treatment of brittle crack tips and fundamental cohesive properties.Special emphasis was given to multiscale fracture description and new scale-bridging formulations capable to substantiate recent experiments and tailored to become the basis for innovative computationa...

  8. Low Pore Connectivity in Natural Rock

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Qinhong; Ewing, Robert P.; Dultz, Stefan

    2012-05-15

    As repositories for CO₂ and radioactive waste, as oil and gas reservoirs, and as contaminated sites needing remediation, rock formations play a central role in energy and environmental management. The connectivity of the rock's porespace strongly affects fluid flow and solute transport. This work examines pore connectivity and its implications for fluid flow and chemical transport. Three experimental approaches (imbibition, tracer concentration profiles, and imaging) were used in combination with network modeling. In the imbibition results, three types of imbibition slope [log (cumulative imbibition) vs. log (imbibition time)] were found: the classical 0.5, plus 0.26, and 0.26 transitioning to 0.5. The imbibition slope of 0.26 seen in Indiana sandstone, metagraywacke, and Barnett shale indicates low pore connectivity, in contrast to the slope of 0.5 seen in the well-connected Berea sandstone. In the tracer profile work, rocks exhibited different distances to the plateau porosity, consistent with the pore connectivity from the imbibition tests. Injection of a molten metal into connected pore spaces, followed by 2-D imaging of the solidified alloy in polished thin sections, allowed direct assessment of pore structure and lateral connection in the rock samples. Pore-scale network modeling gave results consistent with measurements, confirming pore connectivity as the underlying cause of both anomalous behaviors: imbibition slope not having the classical value of 0.5, and accessible porosity being a function of distance from the edge. A poorly connected porespace will exhibit anomalous behavior in fluid flow and chemical transport, such as a lower imbibition slope (in air–water system) and diffusion rate than expected from classical behavior.

  9. Low pore connectivity in natural rock.

    Science.gov (United States)

    Hu, Qinhong; Ewing, Robert P; Dultz, Stefan

    2012-05-15

    As repositories for CO(2) and radioactive waste, as oil and gas reservoirs, and as contaminated sites needing remediation, rock formations play a central role in energy and environmental management. The connectivity of the rock's porespace strongly affects fluid flow and solute transport. This work examines pore connectivity and its implications for fluid flow and chemical transport. Three experimental approaches (imbibition, tracer concentration profiles, and imaging) were used in combination with network modeling. In the imbibition results, three types of imbibition slope [log (cumulative imbibition) vs. log (imbibition time)] were found: the classical 0.5, plus 0.26, and 0.26 transitioning to 0.5. The imbibition slope of 0.26 seen in Indiana sandstone, metagraywacke, and Barnett shale indicates low pore connectivity, in contrast to the slope of 0.5 seen in the well-connected Berea sandstone. In the tracer profile work, rocks exhibited different distances to the plateau porosity, consistent with the pore connectivity from the imbibition tests. Injection of a molten metal into connected pore spaces, followed by 2-D imaging of the solidified alloy in polished thin sections, allowed direct assessment of pore structure and lateral connection in the rock samples. Pore-scale network modeling gave results consistent with measurements, confirming pore connectivity as the underlying cause of both anomalous behaviors: imbibition slope not having the classical value of 0.5, and accessible porosity being a function of distance from the edge. A poorly connected porespace will exhibit anomalous behavior in fluid flow and chemical transport, such as a lower imbibition slope (in air-water system) and diffusion rate than expected from classical behavior.

  10. Children and Place: A Natural Connection.

    Science.gov (United States)

    Vickers, Valerie G.; Matthews, Catherine E.

    2002-01-01

    Presents seven outdoor activities on the environment and ecology to be used at the K-12 grade level. Connects students with the environment they live in and develops the critical sense of place. (Contains 26 references.) (YDS)

  11. Pressure transient analysis methods for bounded naturally fractured reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C-C; Raghavan, R.; Reynolds, A.C.; Serra, K.

    1985-06-01

    New methods for analyzing drawdown and buildup pressure data obtained at a well located in an infinite, naturally fractured reservoir were presented recently. In this work, the analysis of both drawdown and buildup data in a bounded, naturally fractured reservoir is considered. For the bounded case, the authors show that five possible flow regimes may be exhibited by drawdown data. They delineate the conditions under which each of these five flow regimes exists and the information that can be obtained from each possible combination of flow regimes. Conditions under which semilog methods can be used to analyze buildup data are discussed for the bounded fractured reservoir case. New Matthews-Brons-Hazebroek (MBH) functions for computing the average reservoir pressure from buildup data are presented.

  12. The wellbore pressure response in naturally fractured reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, A.C.; Chang, W.L.

    1983-10-01

    Recently a new flow regime has been identified for pressure drawdown or buildup data obtained from a well producing a naturally fractured reservoir. During the time period corresponding to this new flow regime, a semilog plot of pressure versus time exhibits a semilog straight line with slope equal to m/2, where m is the slope of both the ''early and late time'' semilog straight lines predicted by the Warren and Root model. The identification of this intermediate time semilog straight line means that pressure data may exhibit as many as three semilog straight lines. A virtually complete analysis of well test pressure data is possible when the data exhibits two or more of the three possible straight lines. In this work we present type curves which can be used to obtain a virtually complete analysis of pressure data when only one of the three semilog straight lines is reflected by the data. Analytical work on the pressure response in a naturally fractured reservoir requires the assumption of a matrix-fracture geometry. One model that has frequently been used assumes that a naturally fractured reservoir is equivalent to a system of plane horizontal fractures. The use of this model suggests that the pressure response should be similar to the pressure response in a two-layer reservoir. In this work, the authors establish the conditions under which the pressure response in a two-layer reservoir with crossflow between the layers will be identical to the pressure response in a naturally fractured reservoir. The twolayer analogue provides information on the well response when the matrix feeds directly into the wellbore. In addition, the authors consider the economic feasibility of stimulating the ''matrix layer''.

  13. Numerical Investigation into the Effect of Natural Fracture Density on Hydraulic Fracture Network Propagation

    Directory of Open Access Journals (Sweden)

    Zhaohui Chong

    2017-07-01

    Full Text Available Hydraulic fracturing is an important method to enhance permeability in oil and gas exploitation projects and weaken hard roofs of coal seams to reduce dynamic disasters, for example, rock burst. It is necessary to fully understand the mechanism of the initiation, propagation, and coalescence of hydraulic fracture network (HFN caused by fluid flow in rock formations. In this study, a coupled hydro-mechanical model was built based on synthetic rock mass (SRM method to investigate the effects of natural fracture (NF density on HFN propagation. Firstly, the geometrical structures of NF obtained from borehole images at the field scale were applied to the model. Secondly, the micro-parameters of the proposed model were validated against the interaction between NF and hydraulic fracture (HF in physical experiments. Finally, a series of numerical simulations were performed to study the mechanism of HFN propagation. In addition, confining pressure ratio (CPR and injection rate were also taken into consideration. The results suggested that the increase of NF density drives the growth of stimulated reservoir volume (SRV, concentration area of injection pressure (CAIP, and the number of cracks caused by NF. The number of tensile cracks caused by rock matrix decrease gradually with the increase of NF density, and the number of shear cracks caused by rock matrix are almost immune to the change of NF density. The propagation orientation of HFN and the breakdown pressure in rock formations are mainly controlled by CPR. Different injection rates would result in a relatively big difference in the gradient of injection pressure, but this difference would be gradually narrowed with the increase of NF density. Natural fracture density is the key factor that influences the percentages of different crack types in HFN, regardless of the value of CPR and injection rate. The proposed model may help predict HFN propagation and optimize fracturing treatment designs in

  14. Discrimination of Natural Fractures Using Well Logging Curve Unit

    Institute of Scientific and Technical Information of China (English)

    Liu Hongqi; Peng Shimi; Zhou Yongyi; Xue Yongchao

    2004-01-01

    It is very difficult to discriminate natural fractures using conventional well log data, especially for most of the matured oilfields in China, because the raw data were acquired with relatively obsolete tools. The raw data include only GR and SP curves, indicative of lithology, AC curves, used to calculate the porosity of the formation, and a set of logging curves from various electrode length resistivity by laterolog. On the other hand, these oilfields usually have a large amount of core data which directly display the characteristics of the formation, and enough information of injection and production. This paper describes an approach through which logging curves are calibrated in terms of the raw data, and then a prototype model of natural fractures is established based on the investigation of core data from 43 wells, totaling 4 000 m in length. A computer program has been developed according to this method. Through analysis and comparison of the features of logging curves, this paper proposes a new concept, the well logging curve unit. By strictly depicting its shape through mathematical methods, the natural facture can be discriminated. This work also suggests an equation to estimate the probability of fracture occurrence, and finally other fracture parameters are calculated using some experimental expressions. With this methodology, logging curves from 100 wells were interpreted, the results of which agree with core data and field information.

  15. Mathematical algorithm development and parametric studies with the GEOFRAC three-dimensional stochastic model of natural rock fracture systems

    Science.gov (United States)

    Ivanova, Violeta M.; Sousa, Rita; Murrihy, Brian; Einstein, Herbert H.

    2014-06-01

    This paper presents results from research conducted at MIT during 2010-2012 on modeling of natural rock fracture systems with the GEOFRAC three-dimensional stochastic model. Following a background summary of discrete fracture network models and a brief introduction of GEOFRAC, the paper provides a thorough description of the newly developed mathematical and computer algorithms for fracture intensity, aperture, and intersection representation, which have been implemented in MATLAB. The new methods optimize, in particular, the representation of fracture intensity in terms of cumulative fracture area per unit volume, P32, via the Poisson-Voronoi Tessellation of planes into polygonal fracture shapes. In addition, fracture apertures now can be represented probabilistically or deterministically whereas the newly implemented intersection algorithms allow for computing discrete pathways of interconnected fractures. In conclusion, results from a statistical parametric study, which was conducted with the enhanced GEOFRAC model and the new MATLAB-based Monte Carlo simulation program FRACSIM, demonstrate how fracture intensity, size, and orientations influence fracture connectivity.

  16. Natural and projectively equivariant quantizations by means of Cartan Connections

    OpenAIRE

    Mathonet, Pierre; Radoux, Fabian

    2006-01-01

    The existence of a natural and projectively equivariant quantization in the sense of Lecomte [20] was proved recently by M. Bordemann [4], using the framework of Thomas-Whitehead connections. We give a new proof of existence using the notion of Cartan projective connections and we obtain an explicit formula in terms of these connections. Our method yields the existence of a projectively equivariant quantization if and only if an \\sl(m+1,\\R)-equivariant quantization exists in the flat situatio...

  17. Statistical analysis of surface lineaments and fractures for characterizing naturally fractured reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Genliang; George, S.A.; Lindsey, R.P.

    1997-08-01

    Thirty-six sets of surface lineaments and fractures mapped from satellite images and/or aerial photos from parts of the Mid-continent and Colorado Plateau regions were collected, digitized, and statistically analyzed in order to obtain the probability distribution functions of natural fractures for characterizing naturally fractured reservoirs. The orientations and lengths of the surface linear features were calculated using the digitized coordinates of the two end points of each individual linear feature. The spacing data of the surface linear features within an individual set were, obtained using a new analytical sampling technique. Statistical analyses were then performed to find the best-fit probability distribution functions for the orientation, length, and spacing of each data set. Twenty-five hypothesized probability distribution functions were used to fit each data set. A chi-square goodness-of-fit test was used to rank the significance of each fit. A distribution which provides the lowest chi-square goodness-of-fit value was considered the best-fit distribution. The orientations of surface linear features were best-fitted by triangular, normal, or logistic distributions; the lengths were best-fitted by PearsonVI, PearsonV, lognormal2, or extreme-value distributions; and the spacing data were best-fitted by lognormal2, PearsonVI, or lognormal distributions. These probability functions can be used to stochastically characterize naturally fractured reservoirs.

  18. 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

  19. The Shear Mechanisms of Natural Fractures during the Hydraulic Stimulation of Shale Gas Reservoirs

    Directory of Open Access Journals (Sweden)

    Zhaobin Zhang

    2016-08-01

    Full Text Available The shearing of natural fractures is important in the permeability enhancement of shale gas reservoirs during hydraulic fracturing treatment. In this work, the shearing mechanisms of natural fractures are analyzed using a newly proposed numerical model based on the displacement discontinuities method. The fluid-rock coupling system of the model is carefully designed to calculate the shearing of fractures. Both a single fracture and a complex fracture network are used to investigate the shear mechanisms. The investigation based on a single fracture shows that the non-ignorable shearing length of a natural fracture could be formed before the natural fracture is filled by pressurized fluid. Therefore, for the hydraulic fracturing treatment of the naturally fractured shale gas reservoirs, the shear strength of shale is generally more important than the tensile strength. The fluid-rock coupling propagation processes of a complex fracture network are simulated under different crustal stress conditions and the results agree well with those of the single fracture. The propagation processes of complex fracture network show that a smaller crustal stress difference is unfavorable to the shearing of natural fractures, but is favorable to the formation of complex fracture network.

  20. Numerical Study on the Permeability of the Hydraulic-Stimulated Fracture Network in Naturally-Fractured Shale Gas Reservoirs

    Directory of Open Access Journals (Sweden)

    Zhaobin Zhang

    2016-09-01

    Full Text Available As hydraulic fracturing is a fluid-rock coupling process, the permeability of the hydraulic-stimulated fracture network in the initial stage has great effects on the propagation of the hydraulic fracture network in the following stages. In this work, the permeability of the hydraulic-stimulated fracture network in shale gas reservoirs is investigated by a newly-proposed model based on the displacement discontinuity method. The permeability of the fracture network relies heavily on fracture apertures, which can be calculated with high precision by the displacement discontinuity method. The hydraulic fracturing processes are simulated based on the natural fracture networks reconstructed from the shale samples in the Longmaxi formation of China. The flow fields are simulated and the permeability is calculated based on the fracture configurations and fracture apertures after hydraulic fracturing treatment. It is found that the anisotropy of the permeability is very strong, and the permeability curves have similar shapes. Therefore, a fitting equation of the permeability curve is given for convenient use in the future. The permeability curves under different fluid pressures and crustal stress directions are obtained. The results show that the permeability anisotropy is stronger when the fluid pressure is higher. Moreover, the permeability anisotropy reaches the minimum value when the maximum principle stress direction is perpendicular to the main natural fracture direction. The investigation on the permeability is useful for answering how the reservoirs are hydraulically stimulated and is useful for predicting the propagation behaviors of the hydraulic fracture network in shale gas reservoirs.

  1. Measuring an Emotional Connection to Nature among Children

    Science.gov (United States)

    Silvas, Daniel Villalobos

    2013-01-01

    There is a growing concern from scientists and others that children today are losing their connection with nature. The degree of connectedness to nature (CN) has been hypothesized to influence a person's willingness to protect it. Unfortunately, tools used to measure CN are in their infancy and have mostly been developed for adult populations…

  2. Measuring an Emotional Connection to Nature among Children

    Science.gov (United States)

    Silvas, Daniel Villalobos

    2013-01-01

    There is a growing concern from scientists and others that children today are losing their connection with nature. The degree of connectedness to nature (CN) has been hypothesized to influence a person's willingness to protect it. Unfortunately, tools used to measure CN are in their infancy and have mostly been developed for adult populations…

  3. Natural connections on conformal Riemannian P-manifolds

    CERN Document Server

    Gribacheva, Dobrinka

    2011-01-01

    The class of conformal Riemannian P-manifolds is the largest class of Riemannian almost product manifolds, which is closed with respect to the group of the conformal transformations of the Riemannian metric. This class is an analogue of the class of conformal Kaehler manifolds in almost Hermitian geometry. In the present work we study on a conformal Riemannian P-manifold (M, P, g) the natural linear connections, i.e. the linear connections preserving the almost product structure P and the Riemannian metric g. We find necessary and sufficient conditions the curvature tensor of such a connection to have similar properties like the ones of the Kaehler tensor in Hermitian geometry. We determine the type of the manifolds admitting a natural connection with a parallel torsion.

  4. Numerical Simulation of the Propagation of Hydraulic and Natural Fracture Using Dijkstra’s Algorithm

    Directory of Open Access Journals (Sweden)

    Yanfang Wu

    2016-07-01

    Full Text Available Utilization of hydraulic-fracturing technology is dramatically increasing in exploitation of natural gas extraction. However the prediction of the configuration of propagated hydraulic fracture is extremely challenging. This paper presents a numerical method of obtaining the configuration of the propagated hydraulic fracture into discrete natural fracture network system. The method is developed on the basis of weighted fracture which is derived in combination of Dijkstra’s algorithm energy theory and vector method. Numerical results along with experimental data demonstrated that proposed method is capable of predicting the propagated hydraulic fracture configuration reasonably with high computation efficiency. Sensitivity analysis reveals a number of interesting observation results: the shortest path weight value decreases with increasing of fracture density and length, and increases with increasing of the angle between fractures to the maximum principal stress direction. Our method is helpful for evaluating the complexity of the discrete fracture network, to obtain the extension direction of the fracture.

  5. 3D reconstruction method and connectivity rules of fracture networks generated under different mining layouts

    Institute of Scientific and Technical Information of China (English)

    Zhang Ru; Ai Ting; Li Hegui; Zhang Zetian; Liu Jianfeng

    2013-01-01

    In current research, a series of triaxial tests, which were employed to simulate three typical mining lay-outs (i.e., top-coal caving, non-pillar mining and protected coal seam mining), were conducted on coal by using MTS815 Flex Test GT rock mechanics test system, and the fracture networks in the broken coal samples were qualitatively and quantitatively investigated by employing CT scanning and 3D reconstruc-tion techniques. This work aimed at providing a detail description on the micro-structure and fracture-connectivity characteristics of rupture coal samples under different mining layouts. The results show that: (i) for protected coal seam mining layout, the coal specimens failure is in a compression-shear manner and oppositely, (ii) the tension-shear failure phenomenon is observed for top-coal caving and non-pillar mining layouts. By investigating the connectivity features of the generated fractures in the direction of r1 under different mining layouts, it is found that the connectivity level of the fractures of the samples corresponding to non-pillar mining layout was the highest.

  6. Natural fracture systems on planetary surfaces: Genetic classification and pattern randomness

    Science.gov (United States)

    Rossbacher, Lisa A.

    1987-01-01

    One method for classifying natural fracture systems is by fracture genesis. This approach involves the physics of the formation process, and it has been used most frequently in attempts to predict subsurface fractures and petroleum reservoir productivity. This classification system can also be applied to larger fracture systems on any planetary surface. One problem in applying this classification system to planetary surfaces is that it was developed for ralatively small-scale fractures that would influence porosity, particularly as observed in a core sample. Planetary studies also require consideration of large-scale fractures. Nevertheless, this system offers some valuable perspectives on fracture systems of any size.

  7. Fractal modeling of natural fracture networks. Final report, June 1994--June 1995

    Energy Technology Data Exchange (ETDEWEB)

    Ferer, M.V.; Dean, B.H.; Mick, C.

    1996-04-01

    Recovery from naturally fractured, tight-gas reservoirs is controlled by the fracture network. Reliable characterization of the actual fracture network in the reservoir is severely limited. The location and orientation of fractures intersecting the borehole can be determined, but the length of these fractures cannot be unambiguously determined. Fracture networks can be determined for outcrops, but there is little reason to believe that the network in the reservoir should be identical because of the differences in stresses and history. Because of the lack of detailed information about the actual fracture network, modeling methods must represent the porosity and permeability associated with the fracture network, as accurately as possible with very little apriori information. Three rather different types of approaches have been used: (1) dual porosity simulations; (2) `stochastic` modeling of fracture networks, and (3) fractal modeling of fracture networks. Stochastic models which assume a variety of probability distributions of fracture characteristics have been used with some success in modeling fracture networks. The advantage of these stochastic models over the dual porosity simulations is that real fracture heterogeneities are included in the modeling process. In the sections provided in this paper the authors will present fractal analysis of the MWX site, using the box-counting procedure; (2) review evidence testing the fractal nature of fracture distributions and discuss the advantages of using their fractal analysis over a stochastic analysis; (3) present an efficient algorithm for producing a self-similar fracture networks which mimic the real MWX outcrop fracture network.

  8. Automatic retrieval of bone fracture knowledge using natural language processing.

    Science.gov (United States)

    Do, Bao H; Wu, Andrew S; Maley, Joan; Biswal, Sandip

    2013-08-01

    Natural language processing (NLP) techniques to extract data from unstructured text into formal computer representations are valuable for creating robust, scalable methods to mine data in medical documents and radiology reports. As voice recognition (VR) becomes more prevalent in radiology practice, there is opportunity for implementing NLP in real time for decision-support applications such as context-aware information retrieval. For example, as the radiologist dictates a report, an NLP algorithm can extract concepts from the text and retrieve relevant classification or diagnosis criteria or calculate disease probability. NLP can work in parallel with VR to potentially facilitate evidence-based reporting (for example, automatically retrieving the Bosniak classification when the radiologist describes a kidney cyst). For these reasons, we developed and validated an NLP system which extracts fracture and anatomy concepts from unstructured text and retrieves relevant bone fracture knowledge. We implement our NLP in an HTML5 web application to demonstrate a proof-of-concept feedback NLP system which retrieves bone fracture knowledge in real time.

  9. Creating permeable fracture networks for EGS: Engineered systems versus nature

    Energy Technology Data Exchange (ETDEWEB)

    Stephen L Karner

    2005-10-01

    The United States Department of Energy has set long-term national goals for the development of geothermal energy that are significantly accelerated compared to historical development of the resource. To achieve these goals, it is crucial to evaluate the performance of previous and existing efforts to create enhanced geothermal systems (EGS). Two recently developed EGS sites are evaluated from the standpoint of geomechanics. These sites have been established in significantly different tectonic regimes: 1. compressional Cooper Basin (Australia), and 2. extensional Soultz-sous-Fôrets (France). Mohr-Coulomb analyses of the stimulation procedures employed at these sites, coupled with borehole observations, indicate that pre-existing fractures play a significant role in the generation of permeability networks. While pre-existing fabric can be exploited to produce successful results for geothermal energy development, such fracture networks may not be omnipresent. For mostly undeformed reservoirs, it may be necessary to create new fractures using processes that merge existing technologies or use concepts borrowed from natural hydrofracture examples (e.g. dyke swarms).

  10. Communicating Mathematically: Children's Literature as a Natural Connection.

    Science.gov (United States)

    Moyer, Patricia S.

    2000-01-01

    Addresses ways in which children's literature promotes mathematical communication. Describes the natural connections between mathematics and children's literature. Provides a list of resources for teacher use. Describes classroom experiences and activities in which literature is a springboard for children's mathematical communication. (SR)

  11. Connecting Children and Family with Nature-Based Physical Activity

    Science.gov (United States)

    Flett, M. Ryan; Moore, Rebecca W.; Pfeiffer, Karin A.; Belonga, Joyce; Navarre, Julie

    2010-01-01

    Background: As the obesity epidemic expands to include younger Americans, there is greater need to understand youth experiences and to identify innovative strategies to promote physical activity in children and adolescents. Connecting children and families with nature-based activities is an example of a strategy that may promote physical activity…

  12. INVESTIGATION OF EFFICIENCY IMPROVEMENTS DURING CO2 INJECTION IN HYDRAULICALLY AND NATURALLY FRACTURED RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    David S. Schechter

    2005-09-28

    The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in more efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. To achieve this objective, we divided the report into two chapters. The first chapter was to image and perform experimental investigation of transfer mechanisms during CO{sub 2} flooding in NFR and HFR using X-ray CT scanner. In this chapter, we emphasized our work on understanding the connection between fracture properties and fundamentals of transfer mechanism from matrix to fractures and fluid flow through fracture systems. We started our work by investigating the effect of different overburden pressures and stress-state conditions on rock properties and fluid flow. Since the fracture aperture is one of important parameter that governs the fluid flow through the fracture systems, the average fracture aperture from the fluid flow experiments and fracture aperture distribution derived from X-ray CT scan were estimated for our modeling purposes. The fracture properties and fluid flow have significant changes in response to different overburden pressures and stress-state conditions. The fracture aperture distribution follows lognormal distribution even at elevated stress conditions. Later, we also investigated the fluid transfers between matrix and fracture that control imbibition process. We evaluated dimensionless time for validating the scheme of upscaling laboratory experiments to field dimensions. In CO{sub 2} injection experiments, the use of X-ray CT has allowed us to understand the mechanisms of CO{sub 2} flooding process in fractured system and to take important steps in reducing oil bypassed. When CO{sub 2} flooding experiments were performed on a short core with a fracture at the center of the core, the gravity plays an important role in the recovery of oil

  13. A semi-analytical model for the flow behavior of naturally fractured formations with multi-scale fracture networks

    Science.gov (United States)

    Jia, Pin; Cheng, Linsong; Huang, Shijun; Wu, Yonghui

    2016-06-01

    This paper presents a semi-analytical model for the flow behavior of naturally fractured formations with multi-scale fracture networks. The model dynamically couples an analytical dual-porosity model with a numerical discrete fracture model. The small-scale fractures with the matrix are idealized as a dual-porosity continuum and an analytical flow solution is derived based on source functions in Laplace domain. The large-scale fractures are represented explicitly as the major fluid conduits and the flow is numerically modeled, also in Laplace domain. This approach allows us to include finer details of the fracture network characteristics while keeping the computational work manageable. For example, the large-scale fracture network may have complex geometry and varying conductivity, and the computations can be done at predetermined, discrete times, without any grids in the dual-porosity continuum. The validation of the semi-analytical model is demonstrated in comparison to the solution of ECLIPSE reservoir simulator. The simulation is fast, gridless and enables rapid model setup. On the basis of the model, we provide detailed analysis of the flow behavior of a horizontal production well in fractured reservoir with multi-scale fracture networks. The study has shown that the system may exhibit six flow regimes: large-scale fracture network linear flow, bilinear flow, small-scale fracture network linear flow, pseudosteady-state flow, interporosity flow and pseudoradial flow. During the first four flow periods, the large-scale fracture network behaves as if it only drains in the small-scale fracture network; that is, the effect of the matrix is negligibly small. The characteristics of the bilinear flow and the small-scale fracture network linear flow are predominantly determined by the dimensionless large-scale fracture conductivity. And low dimensionless fracture conductivity will generate large pressure drops in the large-scale fractures surrounding the wellbore. With

  14. Rigid connections between natural teeth and implants: a technical note.

    Science.gov (United States)

    Lindh, T; Gunne, J; Danielsson, S

    1997-01-01

    In the posterior partially edentulous jaw, implants may be used to supplement existing natural dentition. Frequently, the maxillary sinuses and the mandibular nerve preclude the fabrication of freestanding implant-retained prostheses. However, if an implant and a natural abutment are combined, a fixed prosthesis can be fabricated, restoring the arch into the premolar area. The histories of three patients with attachments connecting implant-retained ceramotitanium crowns with crowns on natural abutments are described. A design for a rigid custom-made attachment for the Brånemark system, using standard components with a machine-duplication, spark-erosion technique, is suggested.

  15. The Nature Relatedness Scale: Linking Individuals' Connection with Nature to Environmental Concern and Behavior

    Science.gov (United States)

    Nisbet, Elizabeth K.; Zelenski, John M.; Murphy, Steven A.

    2009-01-01

    Disconnection from the natural world may be contributing to our planet's destruction. The authors propose a new construct, Nature Relatedness (NR), and a scale that assesses the affective, cognitive, and experiential aspects of individuals' connection to nature. In Study 1, the authors explored the internal structure of the NR item responses in a…

  16. 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.

  17. A failure analysis study on the fractured connecting bolts of a filter press

    Directory of Open Access Journals (Sweden)

    Sh. Molaei

    2015-10-01

    Full Text Available The purpose of this study was to investigate the main causes of the co-fracture of sixteen connecting bolts of a filter press cylinder–piston system. Stress state of the bolts during the service conditions has been analyzed and the failure reasons were determined from the fractography analysis and gathered information. According to the obtained results, it was concluded that the bolts had failed by the fatigue mechanism. It seems that insufficient torque was used during assembly.

  18. Natural processes as means to create local connection

    DEFF Research Database (Denmark)

    Sjøstedt, Victoria

    2010-01-01

    and practical knowledge about how to apply natural processes to planning. This paper investigates how natural process thinking caters for a connection to the local and the site-specific in a Chinese context of transformation. Natural process thinking as a site-based urban design approach is understood......Contemporary large scale residential developments in China are often built up in a tabula rasa fashion, with little consideration to natural and cultural landscapes. Site-specific readings also turn into a difficult endeavor since socio-cultural patterns in China are under rapid transformation......, a particular challenge for foreign architects as they operate in an unfamiliar context. A deep understanding of how to apply natural processes to construction and settlement patterns can be found in Chinese vernacular approaches but are rarely practiced today since architects in general lack more profound...

  19. Natural Products Version 2.0: Connecting Genes to Molecules

    Science.gov (United States)

    Walsh, Christopher T.; Fischbach, Michael A.

    2009-01-01

    Natural products have played a prominent role in the history of organic chemistry, and they continue to be important as drugs, biological probes, and targets of study for synthetic and analytical chemists. In this perspective, we explore how connecting Nature’s small molecules to the genes that encode them has sparked a renaissance in natural product research, focusing primarily on the biosynthesis of polyketides and nonribosomal peptides. We survey monomer biogenesis, coupling chemistries from templated and non-templated pathways, and the broad set of tailoring reactions and hybrid pathways that give rise to the diverse scaffolds and functionalization patterns of natural products. We conclude by considering two questions: What would it take to find all natural product scaffolds? What kind of scientists will be studying natural products in the future? PMID:20121095

  20. Numerical Investigation on Stress Shadowing in Fluid Injection-Induced Fracture Propagation in Naturally Fractured Geothermal Reservoirs

    Science.gov (United States)

    Yoon, Jeoung Seok; Zimmermann, Günter; Zang, Arno

    2015-07-01

    In low permeability shale reservoirs, multi-stage hydraulic fracturing is largely used to increase the productivity by enlarging the stimulated rock volume. Hydraulic fracture created alters the stress field around it, and affects the subsequent fractures by the change of the stress field, in particular, mostly increased minimum principal stress at the area of subsequent fracturing. This is called stress shadow which accumulates as the fracturing stages advance from toe to heel. Hydraulic fractures generated in such altered stress field are shorter and compact with orientation deviating significantly from the far-field maximum horizontal stress orientation. This paper presents 2D discrete element-based numerical modeling of multi-stage hydraulic fracturing in a naturally fractured reservoir and investigates stress shadowing. The stress shadowing is tested with two different injection scenarios: constant and cyclic rate injections. The results show that cyclic injection tends to lower the effect of stress shadow as well as mitigates the magnitude of the induced seismicity. Another modeling case is presented to show how the stress shadow can be utilized to optimize a hydraulic fracture network in application to Groß Schönebeck geothermal reservoir, rather than being mitigated. The modeling demonstrated that the stress shadow is successfully utilized for optimizing the geothermal heat exchanger by altering the initial in situ stress field from highly anisotropic to less or even to isotropic.

  1. Hydraulic fracturing for natural gas: impact on health and environment.

    Science.gov (United States)

    Carpenter, David O

    2016-03-01

    Shale deposits exist in many parts of the world and contain relatively large amounts of natural gas and oil. Recent technological developments in the process of horizontal hydraulic fracturing (hydrofracturing or fracking) have suddenly made it economically feasible to extract natural gas from shale. While natural gas is a much cleaner burning fuel than coal, there are a number of significant threats to human health from the extraction process as currently practiced. There are immediate threats to health resulting from air pollution from volatile organic compounds, which contain carcinogens such as benzene and ethyl-benzene, and which have adverse neurologic and respiratory effects. Hydrogen sulfide, a component of natural gas, is a potent neuro- and respiratory toxin. In addition, levels of formaldehyde are elevated around fracking sites due to truck traffic and conversion of methane to formaldehyde by sunlight. There are major concerns about water contamination because the chemicals used can get into both ground and surface water. Much of the produced water (up to 40% of what is injected) comes back out of the gas well with significant radioactivity because radium in subsurface rock is relatively water soluble. There are significant long-term threats beyond cancer, including exacerbation of climate change due to the release of methane into the atmosphere, and increased earthquake activity due to disruption of subsurface tectonic plates. While fracking for natural gas has significant economic benefits, and while natural gas is theoretically a better fossil fuel as compared to coal and oil, current fracking practices pose significant adverse health effects to workers and near-by residents. The health of the public should not be compromized simply for the economic benefits to the industry.

  2. Simulation studies to evaluate the effect of fracture closure on the performance of naturally fractured reservoirs. Annual report

    Energy Technology Data Exchange (ETDEWEB)

    1992-11-01

    The second year of this three-year research program to evaluate the effect of fracture closure on the recovery of oil and gas from naturally fractured reservoirs has been completed. The overall objectives of the study are to: (1) evaluate the reservoir conditions where fracture closure is significant, and (2) evaluate innovative fluid injection techniques capable of maintaining pressure within the reservoir. Simulation studies have been conducted with a dual porosity simulator capable of simulating the performance of vertical and horizontal wells. Each simulation model has been initialized with properties typical of the Austin Chalk reservoir in Pearsall Field, Texas. During year one, simulations of both vertical and horizontal well performance were made assuming that fracture permeability was insensitive to pressure charge. The results confirmed that horizontal wells could increase both rate of oil recovery and total oil recovery from naturally fractured reservoirs. During the second year the performances of the same vertical and horizontal wells were evaluated with the assumption that fracture permeability was a function of reservoir pressure. This required repetition of most of the natural depletion cases simulated in year one while invoking the pressure-sensitive fracture permeability option. To investigate sensitivity to in situ stress, two stress conditions were simulated for each primary variable. The water injection cases, begun in year one, were extended to include most of the reservoir parameters investigated for natural depletion, including fracture permeability as a function of net stress and the use of horizontal wells. The results thus far confirm that pressure-sensitive fractures degrade well performance and that the degradation is reduced by water injection pressure maintenance. Furthermore, oil recovery can be significantly increased by water injection pressure maintenance.

  3. Evaluation of Energy Saving Operational Modes for Industrial Fracture Connected Processes on the Basis of Incubation Time Fracture Criterion

    Institute of Scientific and Technical Information of China (English)

    Bratov Vladimir; Petrov Yuri

    2008-01-01

    A problem for a central crack in a plate subjected to plane strain conditions is investigated.Mode Ⅰ crack loading is created by a dynamic pressure pulse applied at a large distance from the crack.It was found that for a certain combination of amplitude and duration of the pulse applied,the energy transmitted to the sample has a strongly marked minimum,meaning that with the pulse amplitude or duration moving away from the optimal values,minimum energy required for initiation of crack growth increases rapidly.The results obtained indicate a possibility to optimise energy consumption of different industrial processes connected with fracture.Much could be gained in,for example,drilling or rock pounding where energy input accounts for the largest part of the process cost.Presumably further investigation of the effect observed can make it possible to predict optimal energy saving parameters,i.e.frequency and amplitude of impacts,for industrial devices,e.g.bores,grinding machines,and hence significantly reduce the process cost.The prediction can be given based on the parameters of the media fractured (material parameters,prevalent crack length and orientation,etc.).

  4. Beyond knowing nature: Contact, emotion, compassion, meaning, and beauty are pathways to nature connection.

    Science.gov (United States)

    Lumber, Ryan; Richardson, Miles; Sheffield, David

    2017-01-01

    Feeling connected to nature has been shown to be beneficial to wellbeing and pro-environmental behaviour. General nature contact and knowledge based activities are often used in an attempt to engage people with nature. However the specific routes to nature connectedness have not been examined systematically. Two online surveys (total n = 321) of engagement with, and value of, nature activities structured around the nine values of the Biophila Hypothesis were conducted. Contact, emotion, meaning, and compassion, with the latter mediated by engagement with natural beauty, were predictors of connection with nature, yet knowledge based activities were not. In a third study (n = 72), a walking intervention with activities operationalising the identified predictors, was found to significantly increase connection to nature when compared to walking in nature alone or walking in and engaging with the built environment. The findings indicate that contact, emotion, meaning, compassion, and beauty are pathways for improving nature connectedness. The pathways also provide alternative values and frames to the traditional knowledge and identification routes often used by organisations when engaging the public with nature.

  5. Increasing Children's Positive Connection to, Orientation toward, and Knowledge of Nature through Nature Camp Experiences

    Science.gov (United States)

    San Jose, Alyssa L.; Nelson, Keith E.

    2017-01-01

    What do children actually carry away from participating in planned activities in natural areas such as those in outdoor camps and schools? Prior research has seldom been rigorous in establishing participants' connection to, knowledge of, and orientation toward nature before intervention, followed by a clear specification of what range of…

  6. An investigation on the fracture of linkage connecting wing flap of aircraft

    Science.gov (United States)

    Feng, Yanpeng; Tang, Haijun; Wang, Chun; Shu, Ping; Ma, Xiaoming; Li, Chunguang

    2017-01-01

    Linkage that connected wing flap and supports was found broken several times during from 2011 to 2014. Flights data was check, no heavy landing or exceed limiting speed warning were found. To investigate the root cause of the failure process, macroscopic and micrograph of the fracture surface were research with optical micrograph and scanning electron micrograph. Results show that the surface of fracture was dimples and shearing fracture structure which mean transient breaking features. Nearby the fracture, a lot of scratch and paint marks were found, that indicated that the rod may collapsed by impacted with some mechanical components. But the distance to the nearest component is within the tolerance, during ground inspection. Basing on stability analysis of column, the linkage will be bending deflection with elastic deformation, when compress exceed a critical value, which decrease the distance. But it will be recovered, during ground inspection for lower compress. Finite Element methods were used to demonstrate the bending deformation too. Basing on the reports and analysis, enhanced linkages were provided and substituted for older versions, and the relevant incidents were never found.

  7. Numerical Modeling of Variable Fluid Injection-Rate Modes on Fracturing Network Evolution in Naturally Fractured Formations

    Directory of Open Access Journals (Sweden)

    Yu Wang

    2016-05-01

    Full Text Available In this study, variable injection-rate technology was numerically investigated in a pre-existing discrete fracture network (DFN formation, the Tarim Basin in China. A flow-stress-damage (FSD coupling model has been used in an initial attempt towards how reservoir response to variable injection-rates at different hydraulic fracturing stages. The established numerical model simultaneously considered the macroscopic and microscopic heterogeneity characteristics. Eight numerical cases were studied. Four cases were used to study the variable injection-rate technology, and the other four cases were applied for a constant injection-rate in order to compare with the variable injection-rate technology. The simulation results show that the variable injection-rate technology is a potentially good method to a form complex fracturing networks. The hydraulic fracturing effectiveness when increasing the injection-rate at each stage is the best, also, the total injected fluid is at a minimum. At the initial stage, many under-fracturing points appear around the wellbore with a relatively low injection-rate; the sudden increase of injection rate drives the dynamic propagation of hydraulic fractures along many branching fracturing points. However, the case with decreasing injection rate is the worst. By comparing with constant injection-rate cases, the hydraulic fracturing effectiveness with variable flow rate technology is generally better than those with constant injection-rate technology. This work strongly links the production technology and hydraulic fracturing effectiveness evaluation and aids in the understanding and optimization of hydraulic fracturing simulations in naturally fractured reservoirs.

  8. Simulation studies to evaluate the effect of fracture closure on the performance of naturally fractured reservoirs. Annual report

    Energy Technology Data Exchange (ETDEWEB)

    1991-10-01

    The first of a three-year research program to evaluate the effect of fracture closure on the recovery of oil and gas from naturally fractured reservoirs has been completed. The objectives of the study are to (1) evaluate the reservoir conditions where fracture closure is significant, and (2) evaluate innovative fluid injection techniques capable of maintaining pressure within the reservoir. Simulation studies were conducted with a dual porosity simulator capable of simulating the performance of vertical and horizontal wells. Each simulator was initialized using properties typical of the Austin Chalk reservoir in Pearsall Field, Texas. Simulations of both vertical and horizontal well performance were made assuming that fracture permeability was insensitive to pressure change. Sensitivity runs indicate that the simulator is predicting the effects of critical reservoir parameters in a logical and consistent manner. The results to-date confirm that horizontal wells can increase both oil recovery rate and total oil recovery from naturally fractured reservoirs. The year one simulation results will provide the baseline for the ongoing study which will evaluate the performance degradation caused by the sensitivity of fracture permeability to pressure change, and investigate fluid injection pressure maintenance as a means to improve oil recovery performance. The study is likely to conclude that fracture closure decreases oil recovery and that pressure support achieved through fluid injection could be beneficial in improving recovery.

  9. INVESTIGATION OF EFFICIENCY IMPROVEMENTS DURING CO2 INJECTION IN HYDRAULICALLY AND NATURALLY FRACTURED RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    David S. Schechter

    2005-04-27

    This report describes the work performed during the fourth year of the project, ''Investigating of Efficiency Improvements during CO{sub 2} Injection in Hydraulically and Naturally Fractured Reservoirs.'' The objective of this project is to perform unique laboratory experiments with artificially fractured cores (AFCs) and X-ray CT scanner to examine the physical mechanisms of bypassing in hydraulically fractured reservoirs (HFR) and naturally fractured reservoirs (NFR) that eventually result in more efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. In Chapter 1, we worked with DOE-RMOTC to investigate fracture properties in the Tensleep Formation at Teapot Dome Naval Reserve as part of their CO{sub 2} sequestration project. In Chapter 2, we continue our investigation to determine the primary oil recovery mechanism in a short vertically fractured core. Finally in Chapter 3, we report our numerical modeling efforts to develop compositional simulator with irregular grid blocks.

  10. On the evaluation of steam assisted gravity drainage in naturally fractured oil reservoirs

    Directory of Open Access Journals (Sweden)

    Seyed Morteza Tohidi Hosseini

    2017-06-01

    Full Text Available Steam Assisted Gravity Drainage (SAGD as a successful enhanced oil recovery (EOR process has been applied to extract heavy and extra heavy oils. Huge amount of global heavy oil resources exists in carbonate reservoirs which are mostly naturally fractured reservoirs. Unlike clastic reservoirs, few studies were carried out to determine the performance of SAGD in carbonate reservoirs. Even though SAGD is a highly promising technique, several uncertainties and unanswered questions still exist and they should be clarified for expansion of SAGD methods to world wide applications especially in naturally fractured reservoirs. In this communication, the effects of some operational and reservoir parameters on SAGD processes were investigated in a naturally fractured reservoir with oil wet rock using CMG-STARS thermal simulator. The purpose of this study was to investigate the role of fracture properties including fracture orientation, fracture spacing and fracture permeability on the SAGD performance in naturally fractured reservoirs. Moreover, one operational parameter was also studied; one new well configuration, staggered well pair was evaluated. Results indicated that fracture orientation influences steam expansion and oil production from the horizontal well pairs. It was also found that horizontal fractures have unfavorable effects on oil production, while vertical fractures increase the production rate for the horizontal well. Moreover, an increase in fracture spacing results in more oil production, because in higher fracture spacing model, steam will have more time to diffuse into matrices and heat up the entire reservoir. Furthermore, an increase in fracture permeability results in process enhancement and ultimate recovery improvement. Besides, diagonal change in the location of injection wells (staggered model increases the recovery efficiency in long-term production plan.

  11. 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

  12. An Efficient Upscaling Process Based on a Unified Fine-scale Multi-Physics Model for Flow Simulation in Naturally Fracture Carbonate Karst Reservoirs

    KAUST Repository

    Bi, Linfeng

    2009-01-01

    The main challenges in modeling fluid flow through naturally-fractured carbonate karst reservoirs are how to address various flow physics in complex geological architectures due to the presence of vugs and caves which are connected via fracture networks at multiple scales. In this paper, we present a unified multi-physics model that adapts to the complex flow regime through naturally-fractured carbonate karst reservoirs. This approach generalizes Stokes-Brinkman model (Popov et al. 2007). The fracture networks provide the essential connection between the caves in carbonate karst reservoirs. It is thus very important to resolve the flow in fracture network and the interaction between fractures and caves to better understand the complex flow behavior. The idea is to use Stokes-Brinkman model to represent flow through rock matrix, void caves as well as intermediate flows in very high permeability regions and to use an idea similar to discrete fracture network model to represent flow in fracture network. Consequently, various numerical solution strategies can be efficiently applied to greatly improve the computational efficiency in flow simulations. We have applied this unified multi-physics model as a fine-scale flow solver in scale-up computations. Both local and global scale-up are considered. It is found that global scale-up has much more accurate than local scale-up. Global scale-up requires the solution of global flow problems on fine grid, which generally is computationally expensive. The proposed model has the ability to deal with large number of fractures and caves, which facilitate the application of Stokes-Brinkman model in global scale-up computation. The proposed model flexibly adapts to the different flow physics in naturally-fractured carbonate karst reservoirs in a simple and effective way. It certainly extends modeling and predicting capability in efficient development of this important type of reservoir.

  13. Study on interaction between induced and natural fractures by extended finite element method

    Science.gov (United States)

    Xu, DanDan; Liu, ZhanLi; Zhuang, Zhuo; Zeng, QingLei; Wang, Tao

    2017-02-01

    Fracking is one of the kernel technologies in the remarkable shale gas revolution. The extended finite element method is used in this paper to numerically investigate the interaction between hydraulic and natural fractures, which is an important issue of the enigmatic fracture network formation in fracking. The criteria which control the opening of natural fracture and crossing of hydraulic fracture are tentatively presented. Influence factors on the interaction process are systematically analyzed, which include the approach angle, anisotropy of in-situ stress and fluid pressure profile.

  14. DEVELOPMENT OF RESERVOIR CHARACTERIZATION TECHNIQUES AND PRODUCTION MODELS FOR EXPLOITING NATURALLY FRACTURED RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Michael L. Wiggins; Raymon L. Brown; Faruk Civan; Richard G. Hughes

    2002-12-31

    For many years, geoscientists and engineers have undertaken research to characterize naturally fractured reservoirs. Geoscientists have focused on understanding the process of fracturing and the subsequent measurement and description of fracture characteristics. Engineers have concentrated on the fluid flow behavior in the fracture-porous media system and the development of models to predict the hydrocarbon production from these complex systems. This research attempts to integrate these two complementary views to develop a quantitative reservoir characterization methodology and flow performance model for naturally fractured reservoirs. The research has focused on estimating naturally fractured reservoir properties from seismic data, predicting fracture characteristics from well logs, and developing a naturally fractured reservoir simulator. It is important to develop techniques that can be applied to estimate the important parameters in predicting the performance of naturally fractured reservoirs. This project proposes a method to relate seismic properties to the elastic compliance and permeability of the reservoir based upon a sugar cube model. In addition, methods are presented to use conventional well logs to estimate localized fracture information for reservoir characterization purposes. The ability to estimate fracture information from conventional well logs is very important in older wells where data are often limited. Finally, a desktop naturally fractured reservoir simulator has been developed for the purpose of predicting the performance of these complex reservoirs. The simulator incorporates vertical and horizontal wellbore models, methods to handle matrix to fracture fluid transfer, and fracture permeability tensors. This research project has developed methods to characterize and study the performance of naturally fractured reservoirs that integrate geoscience and engineering data. This is an important step in developing exploitation strategies for

  15. Study on interaction between induced and natural fractures by extended finite element method

    Science.gov (United States)

    Xu, DanDan; Liu, ZhanLi; Zhuang, Zhuo; Zeng, QingLei; Wang, Tao

    2017-02-01

    Fracking is one of the kernel technologies in the remarkable shale gas revolution. The extended finite element method is used in this paper to numerically investigate the interaction between hydraulic and natural fractures, which is an important issue of the enigmatic fracture network formation in fracking. The criteria which control the opening of natural fracture and crossing of hydraulic fracture are tentatively presented. Influence factors on the interaction process are systematically analyzed, which include the approach angle, anisotropy of in-situ stress and fluid pressure profile.

  16. Sedimentological and Stratigraphic Controls on Natural Fracture Distribution in Wajid Group, SW Saudi Arabia

    Science.gov (United States)

    Benaafi, Mohammed; Hariri, Mustafa; Abdullatif, Osman; Makkawi, Mohammed; Korvin, Gabor

    2016-04-01

    The Cambro-Permian Wajid Group, SW Saudi Arabia, is the main groundwater aquifer in Wadi Al-Dawasir and Najran areas. In addition, it has a reservoir potentiality for oil and natural gas in Rub' Al-Khali Basin. Wajid Group divided into four formations, ascending Dibsiyah, Sanamah, Khussyayan and Juwayl. They are mainly sandstone and exposed in an area extend from Wadi Al-Dawasir southward to Najran city and deposited within fluvial, shallow marine and glacial environments. This study aims to investigate the sedimentological and stratigraphic controls on the distribution of natural fractures within Wajid Group outcrops. A scanline sampling method was used to study the natural fracture network within Wajid Group outcrops, where the natural fractures were measured and characterized in 12 locations. Four regional natural fracture sets were observed with mean strikes of 050o, 075o, 345o, and 320o. Seven lithofacies characterized the Wajid Group at these locations and include fine-grained sandstone, coarse to pebbly sandstone, cross-bedded sandstone, massive sandstone, bioturbated sandstone, conglomerate sandstone, and conglomerate lithofacies. We found that the fine-grained and small scale cross-bedded sandstones lithofacies are characterized by high fracture intensity. In contrast, the coarse-grained sandstone and conglomerate lithofacies have low fracture intensity. Therefore, the relative fracture intensity and spacing of natural fractures within Wajid Group in the subsurface can be predicted by using the lithofacies and their depositional environments. In terms of stratigraphy, we found that the bed thickness and the stratigraphic architecture are the main controls on fractures intensity. The outcomes of this study can help to understand and predict the natural fracture distribution within the subsurface fractured sandstone hosting groundwater and hydrocarbon in Wajid and Rub' Al-Khali Basins. Hence, the finding of this study might help to explore and develop the

  17. An investigation of radial tracer flow in naturally fractured reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Jetzabeth, Ramirez-Sabag; Fernando, Samaniego V.; Jesus, Rivera R.; Fernando Rodriguez

    1991-01-01

    This study presents a general solution for the radial flow of tracers in naturally fractured reservoirs. Continuous and finite step injection of chemical and radioactive tracers are considered. The reservoir is treated as being composed of two regions: a mobile region where longitudinal dispersion and convection take place and a stagnant region where only diffusion and adsorption are allowed. Radioactive decay is considered in both regions. The model of this study is thoroughly compared to those previously presented in literature by Moench and Ogata, Tang et al., Chen et al., and Hsieh et al. The solution is numerically inverted by means of the Crump algorithm. A detailed validation of the model with respect to solutions previously presented and/or simplified physical conditions solutions (i.e., homogeneous case) or limit solutions (i.e., for short times) was carried out. The influence of various dimensionless parameters that enter into the solution was investigated. A discussion of results obtained through the Crump and Stehfest algorithm is presented, concluding that the Crump method provides more reliable tracer concentrations.

  18. Coupling Geomechanics and Transport in Naturally Fractured Reservoirs

    Directory of Open Access Journals (Sweden)

    M.R Jalali

    2012-12-01

    Full Text Available Large amounts of hydrocarbon reserves are trapped in naturally fractured reservoirs which arechallenging in terms of accurate recovery prediction because of their joint fabric complexity andlithological heterogeneity. Canada, for example, has over 400 billion barrels of crude oil in fracturedcarbonates in Alberta, most of this being bitumen of viscosity greater than 106 cP in the GrosmontFormation, which has an average porosity of about 13-15%. Thermal methods are the most commonexploitation approaches in such viscous oil reservoirs which, in the case of steam injection, are associatedwith up to 275-300°C temperature changes, leading to considerable thermoelastic expansion. Thistemperature change, combined with pore pressure changes from injection and production processes, leadsto massive effective stress variations in the reservoir and surrounding rocks. The thermally-induced(thermoelastic stress changes can easily be an order of magnitude greater than the pore pressure effectsbecause of the high intrinsic stiffness of the low porosity limestone and bounding strata. Study of thesestress-pressure-temperature effects requires a thermo-hydro-mechanical (THM coupling approach whichconsiders the simultaneous variation of effective stress, pore pressure, and temperature and theirinteractions. For example, thermal expansion can lead to significant joint dilation, increasing themacroscopic, joint-dominated transmissivity by an order of magnitude in front of and normal to thethermal front, while reducing it in the direction tangential to the heating front. This leads to stronginduced anisotropy of transport processes, which in turn affects the spatial distribution of the heatingarising from advective heat transfer.

  19. Cross-borehole flow analysis to characterize fracture connections in the Melechov Granite, Bohemian-Moravian Highland, Czech Republic

    Science.gov (United States)

    Paillet, Frederick L.; Williams, John H.; Urik, Joseph; Lukes, Joseph; Kobr, Miroslav; Mares, Stanislav

    2012-01-01

    Application of the cross-borehole flow method, in which short pumping cycles in one borehole are used to induce time-transient flow in another borehole, demonstrated that a simple hydraulic model can characterize the fracture connections in the bedrock mass between the two boreholes. The analysis determines the properties of fracture connections rather than those of individual fractures intersecting a single borehole; the model contains a limited number of adjustable parameters so that any correlation between measured and simulated flow test data is significant. The test was conducted in two 200-m deep boreholes spaced 21 m apart in the Melechov Granite in the Bohemian-Moravian Highland, Czech Republic. Transient flow was measured at depth stations between the identified transmissive fractures in one of the boreholes during short-term pumping and recovery periods in the other borehole. Simulated flows, based on simple model geometries, closely matched the measured flows. The relative transmissivity and storage of the inferred fracture connections were corroborated by tracer testing. The results demonstrate that it is possible to assess the properties of a fracture flow network despite being restricted to making measurements in boreholes in which a local population of discrete fractures regulates the hydraulic communication with the larger-scale aquifer system.

  20. Connection with Nature Is an Oxymoron: A Political Ecology of "Nature-Deficit Disorder"

    Science.gov (United States)

    Fletcher, Robert

    2017-01-01

    It has become commonplace to argue that greater "connection with nature" is needed to mobilize support for both biodiversity conservation and environmentalism generally, and hence to call for more effective environmental education to achieve this. I employ a political ecology lens to problematize this increasingly conventional wisdom by…

  1. Does joint architecture influence the nature of intra-articular fractures?

    Science.gov (United States)

    Steer, R A; Smith, S D; Lang, A; Hohmann, E; Tetsworth, K D

    2015-07-01

    The architecture of joints has potentially the greatest influence on the nature of intra-articular fractures. We analysed a large number of intra-articular fractures with two aims: (1) to determine if the pattern of injuries observed supports our conjecture that the local skeletal architecture is an important factor and (2) to investigate whether associated dislocations further affect the fracture pattern. A retrospective study of intra-articular fractures over a 3.5-year period; 1003 joints met inclusion criteria and were analysed. Three independent investigators determined if fractures affected the convex dome, the concave socket, or if both joint surfaces were involved. Further review determined if a joint dislocation occurred with the initial injury. Statistical analysis was performed using a one-way frequency table, and the χ(2) test was used to compare the frequencies of concave and convex surface fractures. The odds ratios (ORs) were calculated to establish the association between the frequencies of concave and convex surface fractures, as well as between dislocation and either fracture surface involvement. Of the 1003 fractures analysed, 956 (95.3%) involved only the concavity of the joint; in 21 fractures (2.1%) both joint surfaces were involved; and in 26 fractures (2.6%) only the convexity was involved (χ(2)=1654.9, df=2, parchitecture of joints clearly plays a highly significant role in determining the nature of intra-articular fractures. Intra-articular fractures involving the convexity are much more likely to be associated with a concurrent joint dislocation. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

  2. Fixation of tibial plateau fractures with synthetic bone graft versus natural bone graft: a comparison study.

    LENUS (Irish Health Repository)

    Ong, J C Y

    2012-06-01

    The goal of this study was to determine differences in fracture stability and functional outcome between synthetic bone graft and natural bone graft with internal fixation of tibia plateau metaphyseal defects.

  3. Modeling of Immiscible, Two-Phase Flows in a Natural Rock Fracture

    Energy Technology Data Exchange (ETDEWEB)

    Crandall, Dustin; Ahmadi, Goodarz; Smith, Duane H

    2009-01-01

    One potential method of geologically sequestering carbon dioxide (CO2) is to inject the gas into brine-filled, subsurface formations. Within these low-permeability rocks, fractures exist that can act as natural fluid conduits. Understanding how a less viscous fluid moves when injected into an initially saturated rock fracture is important for the prediction of CO2 transport within fractured rocks. Our study examined experimentally and numerically the motion of immiscible fluids as they were transported through models of a fracture in Berea sandstone. The natural fracture geometry was initially scanned using micro-computerized tomography (CT) at a fine volume-pixel (voxel) resolution by Karpyn et al. [1]. This CT scanned fracture was converted into a numerical mesh for two-phase flow calculations using the finite-volume solver FLUENT® and the volume-of-fluid method. Additionally, a translucent experimental model was constructed using stereolithography. The numerical model was shown to agree well with experiments for the case of a constant rate injection of air into the initially water-saturated fracture. The invading air moved intermittently, quickly invading large-aperture regions of the fracture. Relative permeability curves were developed to describe the fluid motion. These permeability curves can be used in reservoir-scale discrete fracture models for predictions of fluid motion within fractured geological formations. The numerical model was then changed to better mimic the subsurface conditions at which CO2 will move into brine saturated fractures. The different fluid properties of the modeled subsurface fluids were shown to increase the amount of volume the less-viscous invading gas would occupy while traversing the fracture.

  4. Role of Medicinal Plants and Natural Products on Osteoporotic Fracture Healing

    Directory of Open Access Journals (Sweden)

    Mohd Azri Abd Jalil

    2012-01-01

    Full Text Available Popularly known as “the silent disease” since early symptoms are usually absent, osteoporosis causes progressive bone loss, which renders the bones susceptible to fractures. Bone fracture healing is a complex process consisting of four overlapping phases—hematoma formation, inflammation, repair, and remodeling. The traditional use of natural products in bone fractures means that phytochemicals can be developed as potential therapy for reducing fracture healing period. Located closely near the equator, Malaysia has one of the world’s largest rainforests, which are homes to exotic herbs and medicinal plants. Eurycoma longifolia (Tongkat Ali, Labisia pumila (Kacip Fatimah, and Piper sarmentosum (Kaduk are some examples of the popular ethnic herbs, which have been used in the Malay traditional medicine. This paper focuses on the use of natural products for treating fracture as a result of osteoporosis and expediting its healing.

  5. Molecular and Genetic Basis of Hereditary Connective-Tissue Diseases Accompanied by Frequent Fractures

    Directory of Open Access Journals (Sweden)

    G. T. Yakhyaeva

    2016-01-01

    Full Text Available Frequent bone fractures in infancy require the elimination of a large number (> 100 of genetic disorders. The modern diagnostic method of hereditary diseases characterized by debilitating course is a new generation sequencing. The article presents the results of molecular-genetic study conducted in 18 patients with clinical symptoms of connective tissue disorders. 10 (56% patients had mutations in the genes encoding type I collagen chains, leading to the development of osteogenesis imperfecta, 5 (28% — mutations in IV and V type collagen genes that are responsible for the development of Ehlers-Danlos syndrome. 3 (17% patients had mutations in the gene encoding fibrillin-1 protein, deficiency of which is manifested by Marfan syndrome. However, the correlation between patient's phenotype and discovered mutations in the investigated gene is established not in all cases.

  6. Turbulence in laboratory and natural plasmas: Connecting the dots

    Science.gov (United States)

    Jenko, Frank

    2015-11-01

    It is widely recognized that turbulence is an important and fascinating frontier topic of both basic and applied plasma physics. Numerous aspects of this paradigmatic example of self-organization in nonlinear systems far from thermodynamic equilibrium remain to be better understood. Meanwhile, for both laboratory and natural plasmas, an impressive combination of new experimental and observational data, new theoretical concepts, and new computational capabilities (on the brink of the exascale era) have become available. Thus, it seems fair to say that we are currently facing a golden age of plasma turbulence research, characterized by fundamental new insights regarding the role and nature of turbulent processes in phenomena like cross-field transport, particle acceleration and propagation, plasma heating, magnetic reconnection, or dynamo action. At the same time, there starts to emerge a more unified view of this key topic of basic plasma physics, putting it into the much broader context of complex systems research and connecting it, e.g., to condensed matter physics and biophysics. I will describe recent advances and future challenges in this vibrant area of plasma physics, highlighting novel insights into the redistribution and dissipation of energy in turbulent plasmas at kinetic scales, using gyrokinetic, hybrid, and fully kinetic approaches in a complementary fashion. In this context, I will discuss, among other things, the influence of damped eigenmodes, the importance of nonlocal interactions, the origin and nature of non-universal power law spectra, as well as the role of coherent structures. Moreover, I will outline exciting new research opportunities on the horizon, combining extreme scale simulations with basic plasma and fusion experiments as well as with observations from satellites.

  7. How can horizontal wells help in naturally fractured reservoir characterization?

    Energy Technology Data Exchange (ETDEWEB)

    Mazouzi, A.; Deghmoum, A.; Azzouguen, A. [Sonatrach Inc., Hydra (Algeria); Oudjida, A. [Anadarko Inc., (Algeria)

    2000-11-01

    Two successfully drilled horizontal gas wells in the Tin Fouye Tabankort (TFT) fractured reservoir in Algeria were described. The productivity index of horizontal wells compared to vertical wells depends on the pay zone height, vertical anisotropy, lateral anisotropy, the length of the horizontal drain and the amplitude of the damaged zone. Transient tests in horizontal wells can solve the problem of quantifying the vertical and lateral anisotropies. Horizontal wells also minimize the turbulence effects in the vicinity of the wellbore, particularly in gas wells. The two horizontal wells in the TFT reservoir provide an important gas flow rate. The productivity index for each well is triple that of a vertical well. The permeability tensor on the TFT reservoir is established on the basis of transient test reconstitution using numerical simulation. The vertical permeability yields the best match for pressure response. It can be shown as a translation effect in time at the beginning of the linear flow regime. The horizontal anisotropy reacts to the translation of pressure and its derivative in the vertical direction. The configuration of the reservoir shows a high lateral anisotropy with regards to permeability. The vertical permeability can be considered as the composite permeability of both the matrix and fractures. Numerical and laboratory studies show that low permeability is due to fracture opening. Therefore, fracture doesn't necessarily enhance permeability. 8 refs., 3 tabs., 13 figs.

  8. An element-based finite-volume method approach for naturally fractured compositional reservoir simulation

    Energy Technology Data Exchange (ETDEWEB)

    Marcondes, Francisco [Federal University of Ceara, Fortaleza (Brazil). Dept. of Metallurgical Engineering and Material Science], e-mail: marcondes@ufc.br; Varavei, Abdoljalil; Sepehrnoori, Kamy [The University of Texas at Austin (United States). Petroleum and Geosystems Engineering Dept.], e-mails: varavei@mail.utexas.edu, kamys@mail.utexas.edu

    2010-07-01

    An element-based finite-volume approach in conjunction with unstructured grids for naturally fractured compositional reservoir simulation is presented. In this approach, both the discrete fracture and the matrix mass balances are taken into account without any additional models to couple the matrix and discrete fractures. The mesh, for two dimensional domains, can be built of triangles, quadrilaterals, or a mix of these elements. However, due to the available mesh generator to handle both matrix and discrete fractures, only results using triangular elements will be presented. The discrete fractures are located along the edges of each element. To obtain the approximated matrix equation, each element is divided into three sub-elements and then the mass balance equations for each component are integrated along each interface of the sub-elements. The finite-volume conservation equations are assembled from the contribution of all the elements that share a vertex, creating a cell vertex approach. The discrete fracture equations are discretized only along the edges of each element and then summed up with the matrix equations in order to obtain a conservative equation for both matrix and discrete fractures. In order to mimic real field simulations, the capillary pressure is included in both matrix and discrete fracture media. In the implemented model, the saturation field in the matrix and discrete fractures can be different, but the potential of each phase in the matrix and discrete fracture interface needs to be the same. The results for several naturally fractured reservoirs are presented to demonstrate the applicability of the method. (author)

  9. Modeling the Interaction Between Hydraulic and Natural Fractures Using Dual-Lattice Discrete Element Method

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Jing [Universiyt of Utah; Huang, Hai [Idaho National Lab. (INL), Idaho Falls, ID (United States); Deo, Milind

    2015-10-01

    The interaction between hydraulic fractures (HF) and natural fractures (NF) will lead to complex fracture networks due to the branching and merging of natural and hydraulic fractures in unconventional reservoirs. In this paper, a newly developed hydraulic fracturing simulator based on discrete element method is used to predict the generation of complex fracture network in the presence of pre-existing natural fractures. By coupling geomechanics and reservoir flow within a dual lattice system, this simulator can effectively capture the poro-elastic effects and fluid leakoff into the formation. When HFs are intercepting single or multiple NFs, complex mechanisms such as direct crossing, arresting, dilating and branching can be simulated. Based on the model, the effects of injected fluid rate and viscosity, the orientation and permeability of NFs and stress anisotropy on the HF-NF interaction process are investigated. Combined impacts from multiple parameters are also examined in the paper. The numerical results show that large values of stress anisotropy, intercepting angle, injection rate and viscosity will impede the opening of NFs.

  10. Natural hydraulic fractures and the mechanical stratigraphy of shale-dominated strata

    Science.gov (United States)

    Imber, Jonathan; Armstrong, Howard; Atar, Elizabeth; Clancy, Sarah; Daniels, Susan; Grattage, Joshua; Herringshaw, Liam; Trabucho-Alexandre, João; Warren, Cassandra; Wille, Jascha; Yahaya, Liyana

    2016-04-01

    The aim of this study is to investigate stratigraphic variations in the spatial distribution and density of natural hydraulic and other fractures within oil mature, shale-dominated strata from the Cleveland Basin, northeast England. The studied interval includes the Pliensbachian Cleveland Ironstone and Toarcian Whitby Mudstone Formations. The Cleveland Ironstone Formation (ca. 25m thick) consists of silt- and mudstone units with discrete ironstone layers (seams). Ironstones account for 20% of the thickness of the formation. The Whitby Mudstone Formation is up to ca. 100 m thick; up to 2% of its total thickness consists of discrete calcium carbonate horizons, such as the Top Jet Dogger. Natural hydraulic fractures, characterised by plumose marks and concentric arrest lines on fracture surfaces are ubiquitous throughout both formations; shear fractures with mm- to cm-scale displacements occur locally, particularly within silt- and mudstones. Natural hydraulic fractures locally contain thin, sometimes fibrous, calcite fills and are commonly observed to terminate at bedding plane interfaces between silt- or mudstone and carbonate beds. We have recorded fracture locations and apertures along 139 transects in both shale (i.e. silt- and mudstone intervals) and carbonate strata. Natural hydraulic and shear fractures, measured along transects up to 50m long within all lithologies in both formations, typically display uniform distributions. There is no correlation between spacing distribution and bulk extension in any lithology. Median fracture densities recorded within the Cleveland Ironstone Formation are higher in intervening ironstone beds (<2.1 fractures per m in ironstone layers) compared with dominant shales (<0.9 fractures per m in silt- and mudstones). A qualitatively similar pattern occurs within the Whitby Mudstone Formation. However, the absolute values of median fracture density within different members of the Whitby Mudstone Formation range from 2

  11. Invariant tensors related with natural connections for a class Riemannian product manifolds

    OpenAIRE

    Gribacheva, Dobrinka

    2012-01-01

    Some invariant tensors in two Naveira classes of Riemannian product manifolds are considered. These tensors are related with natural connections, i.e. linear connections preserving the Riemannian metric and the product structure.

  12. INVESTIGATION OF EFFICIENCY IMPROVEMENTS DURING CO2 INJECTION IN HYDRAULICALLY AND NATURALLY FRACTURED RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    David S. Schechter

    2003-10-01

    This report describes the work performed during the second year of the project, ''Investigating of Efficiency Improvements during CO{sub 2} Injection in Hydraulically and Naturally Fractured Reservoirs.'' The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in less efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. To achieve this objective, in this period we concentrated our effort on modeling the fluid flow in fracture surface, examining the fluid transfer mechanisms and describing the fracture aperture distribution under different overburden pressure using X-ray CT scanner.

  13. INVESTIGATION OF EFFICIENCY IMPROVEMENTS DURING CO2 INJECTION IN HYDRAULICALLY AND NATURALLY FRACTURED RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    David S. Schechter

    2004-04-26

    This report describes the work performed during the second year of the project, ''Investigating of Efficiency Improvements during CO{sub 2} Injection in Hydraulically and Naturally Fractured Reservoirs.'' The objective of this project is to perform unique laboratory experiments with artificial fractured cores (AFCs) and X-ray CT to examine the physical mechanisms of bypassing in HFR and NFR that eventually result in less efficient CO{sub 2} flooding in heterogeneous or fracture-dominated reservoirs. To achieve this objective, in this period we concentrated our effort on investigating the effect of CO{sub 2} injection rates in homogeneous and fractured cores on oil recovery and a strategy to mitigate CO{sub 2} bypassing in a fractured core.

  14. Connecting Students to Nature--How Intensity of Nature Experience and Student Age Influence the Success of Outdoor Education Programs

    Science.gov (United States)

    Braun, Tina; Dierkes, Paul

    2017-01-01

    Nature connectedness counts as a crucial predictor of pro-environmental behavior. For counteracting today's environmental issues a successful re-connection of individuals to nature is necessary. Besides the promotion of knowledge transfer the aim of the educational program presented in this study is to connect students to their environment. This…

  15. Naturally fractured tight gas: Gas reservoir detection optimization. Quarterly report, January 1--March 31, 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    Economically viable natural gas production from the low permeability Mesaverde Formation in the Piceance Basin, Colorado requires the presence of an intense set of open natural fractures. Establishing the regional presence and specific location of such natural fractures is the highest priority exploration goal in the Piceance and other western US tight, gas-centered basins. Recently, Advanced Resources International, Inc. (ARI) completed a field program at Rulison Field, Piceance Basin, to test and demonstrate the use of advanced seismic methods to locate and characterize natural fractures. This project began with a comprehensive review of the tectonic history, state of stress and fracture genesis of the basin. A high resolution aeromagnetic survey, interpreted satellite and SLAR imagery, and 400 line miles of 2-D seismic provided the foundation for the structural interpretation. The central feature of the program was the 4.5 square mile multi-azimuth 3-D seismic P-wave survey to locate natural fracture anomalies. The interpreted seismic attributes are being tested against a control data set of 27 wells. Additional wells are currently being drilled at Rulison, on close 40 acre spacings, to establish the productivity from the seismically observed fracture anomalies. A similar regional prospecting and seismic program is being considered for another part of the basin. The preliminary results indicate that detailed mapping of fault geometries and use of azimuthally defined seismic attributes exhibit close correlation with high productivity gas wells. The performance of the ten new wells, being drilled in the seismic grid in late 1996 and early 1997, will help demonstrate the reliability of this natural fracture detection and mapping technology.

  16. 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

  17. Naturally fractured tight gas reservoir detection optimization. Quarterly report, January 1, 1997--March 31, 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-04-01

    This document contains the quarterly report dated January 1-March 31, 1997 for the Naturally Fractured Tight Gas Reservoir Detection Optimization project. Topics covered in this report include AVOA modeling using paraxial ray tracing, AVOA modeling for gas- and water-filled fractures, 3-D and 3-C processing, and technology transfer material. Several presentations from a Geophysical Applications Workshop workbook, workshop schedule, and list of workshop attendees are also included.

  18. Isolation and characterization of connective tissue progenitor cells derived from human fracture-induced hemarthrosis in vitro.

    Science.gov (United States)

    Lee, Sang Yang; Miwa, Masahiko; Sakai, Yoshitada; Kuroda, Ryosuke; Oe, Keisuke; Niikura, Takahiro; Matsumoto, Tomoyuki; Fujioka, Hiroyuki; Doita, Minoru; Kurosaka, Masahiro

    2008-02-01

    In our search for alternative sources of connective tissue progenitor cells that can be obtained with minimal invasion, we studied human intraarticular fracture-induced hemarthrosis of the knee and attempted to isolate connective tissue progenitors from the hemarthrosis. Hemarthrosis was aspirated from the knee joints of 13 patients suffering from intraarticular osteochondral fractures of the knee. Mononuclear cells were isolated from the aspirated hemarthrosis by density gradient separation, and cultured. We were able to obtain fibroblastic adherent cells from the mononuclear cell fractions. Flow cytometry analysis after in vitro expansion on tissue culture plastic revealed that the fibroblastic cells were positive for CD29, CD44, CD105, and CD166, and negative for CD14, CD34, CD45, and CD133. These cells could differentiate in vitro into osteogenic, chondrogenic, and adipogenic cells in the presence of lineage-specific induction factors. These results demonstrate that human intraarticular fracture-induced knee hemarthrosis contains connective tissue progenitor cells with morphologic features, immunophenotypic markers, and differentiation potential that are similar to bone marrow stromal cells. This suggests that hemarthrosis, which is easy to harvest without unnecessary invasion to the patient, has possible future clinical applications such as in tissue-engineered therapies for severe osteochondral defects, posttraumatic osteoarthritis, and delayed fracture unions or nonunions.

  19. Permeability evolution due to dissolution of natural shale fractures reactivated by fracking

    Science.gov (United States)

    Kwiatkowski, Kamil; Kwiatkowski, Tomasz; Szymczak, Piotr

    2015-04-01

    Investigation of cores drilled from gas-bearing shale formations reveals a relatively large number of calcite-cemented fractures. During fracking, some of these fractures will be reactivated [1-2] and may become important flow paths in the resulting fracture system. In this communication, we investigate numerically the effect of low-pH reactive fluid on such fractures. The low-pH fluids can either be pumped during the initial fracking stage (as suggested e.g. by Grieser et al., [3]) or injected later, as part of enhanced gas recovery (EGR) processes. In particular, it has been suggested that CO2 injection can be considered as a method of EGR [4], which is attractive as it can potentially be combined with simultaneous CO2 sequestration. However, when mixed with brine, CO2 becomes acidic and thus can be a dissolving agent for the carbonate cement in the fractures. The dissolution of the cement leads to the enhancement of permeability and interconnectivity of the fracture network and, as a result, increases the overall capacity of the reservoir. Importantly, we show that the dissolution of such fractures proceeds in a highly non-homogeneous manner - a positive feedback between fluid transport and mineral dissolution leads to the spontaneous formation of pronounced flow channels, frequently referred to as "wormholes". The wormholes carry the chemically active fluid deeper inside the system, which dramatically speeds up the overall permeability increase. If the low-pH fluids are used during fracking, then the non-uniform dissolution becomes important for retaining the fracture permeability, even in the absence of the proppant. Whereas a uniformly etched fracture will close tightly under the overburden once the fluid pressure is removed, the nonuniform etching will tend to maintain the permeability since the less dissolved regions will act as supports to keep more dissolved regions open. [1] Gale, J. F., Reed, R. M., Holder, J. (2007). Natural fractures in the Barnett

  20. Nature Journaling: Enhancing Students' Connections to the Environment through Writing

    Science.gov (United States)

    Cormell, Janita; Ivey, Toni

    2012-01-01

    Today's youth are increasingly spending more time indoors and less time outside. As a result, many children have a "nature deficit" (Louv 2005) and little awareness of their role in nature. In this article, the first author describes how she shared her passion for nature with her sixth-grade students through nature journaling and how her students…

  1. Nature Journaling: Enhancing Students' Connections to the Environment through Writing

    Science.gov (United States)

    Cormell, Janita; Ivey, Toni

    2012-01-01

    Today's youth are increasingly spending more time indoors and less time outside. As a result, many children have a "nature deficit" (Louv 2005) and little awareness of their role in nature. In this article, the first author describes how she shared her passion for nature with her sixth-grade students through nature journaling and how her…

  2. Nature Journaling: Enhancing Students' Connections to the Environment through Writing

    Science.gov (United States)

    Cormell, Janita; Ivey, Toni

    2012-01-01

    Today's youth are increasingly spending more time indoors and less time outside. As a result, many children have a "nature deficit" (Louv 2005) and little awareness of their role in nature. In this article, the first author describes how she shared her passion for nature with her sixth-grade students through nature journaling and how her…

  3. Prevalence and nature of dentoalveolar injuries among patients with maxillofacial fractures.

    Science.gov (United States)

    Soukup, J W; Mulherin, B L; Snyder, C J

    2013-01-01

    Although not previously reported, experience suggests that dentoalveolar injury is -common among patients with maxillofacial fractures. The objective of this study was to evaluate and describe the prevalence and nature of dentoalveolar injuries in patients identified with maxillofacial fractures. Medical records of 43 dogs and cats diagnosed with maxillofacial fractures between 2005 and 2012 were reviewed to identify patients with concurrent dentoalveolar injury. Medical records of patients with dentoalveolar injury were abstracted for the following information: signalment (including sex, age and skull type), mechanism of maxillofacial trauma, location and number of maxillofacial fractures, dentoalveolar injury type and location and the number of dentoalveolar injury per patient. Statistical evaluation was performed to determine associations between signalment, mechanism of trauma, location and number of maxillofacial fractures and the prevalence and nature of concurrent dentoalveolar injury. Dentoalveolar injuries are common among patients with maxillofacial trauma. Age and mechanism of trauma are significant predictors of the presence of dentoalveolar injuries in patients with maxillofacial trauma. The findings of this study serve to encourage veterinarians to fully assess the oral cavity in patients with maxillofacial fractures as dentoalveolar injuries are common and can be predicted by age and mechanism of trauma. © 2012 British Small Animal Veterinary Association.

  4. OPTIMIZATION OF INFILL DRILLING IN NATURALLY-FRACTURED TIGHT-GAS RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence W. Teufel; Her-Yuan Chen; Thomas W. Engler; Bruce Hart

    2004-05-01

    A major goal of industry and the U.S. Department of Energy (DOE) fossil energy program is to increase gas reserves in tight-gas reservoirs. Infill drilling and hydraulic fracture stimulation in these reservoirs are important reservoir management strategies to increase production and reserves. Phase II of this DOE/cooperative industry project focused on optimization of infill drilling and evaluation of hydraulic fracturing in naturally-fractured tight-gas reservoirs. The cooperative project involved multidisciplinary reservoir characterization and simulation studies to determine infill well potential in the Mesaverde and Dakota sandstone formations at selected areas in the San Juan Basin of northwestern New Mexico. This work used the methodology and approach developed in Phase I. Integrated reservoir description and hydraulic fracture treatment analyses were also conducted in the Pecos Slope Abo tight-gas reservoir in southeastern New Mexico and the Lewis Shale in the San Juan Basin. This study has demonstrated a methodology to (1) describe reservoir heterogeneities and natural fracture systems, (2) determine reservoir permeability and permeability anisotropy, (3) define the elliptical drainage area and recoverable gas for existing wells, (4) determine the optimal location and number of new in-fill wells to maximize economic recovery, (5) forecast the increase in total cumulative gas production from infill drilling, and (6) evaluate hydraulic fracture simulation treatments and their impact on well drainage area and infill well potential. Industry partners during the course of this five-year project included BP, Burlington Resources, ConocoPhillips, and Williams.

  5. Natural fault and fracture network versus anisotropy in the Lower Paleozoic rocks of Pomerania (Poland)

    Science.gov (United States)

    Haluch, Anna; Rybak-Ostrowska, Barbara; Konon, Andrzej

    2017-04-01

    Knowledge of the anisotropy of rock fabric, geometry and distribution of the natural fault and fracture network play a crucial role in the exploration for unconventional hydrocarbon recourses. Lower Paleozoic rocks from Pomerania within the Polish part of Peri-Baltic Basin, as prospective sequences, can be considered a laboratory for analysis of fault and fracture arrangement in relation to the mineral composition of the host rocks. A microstructural study of core samples from five boreholes in Pomerania indicate that the Silurian succession in the study area is predominantly composed of claystones and mudstones interbedded with thin layers of tuffites. Intervals with a high content of detrital quartz or diagenetic silica also occur. Most of the Silurian deposits are abundant in pyrite framboids forming layers or isolated small concretions. Early diagenetic carbonate concretions are also present. The direction and distribution of natural faults and fractures have resulted not only from paleostress. Preliminary study reveals that the fault and fracture arrangement is related to the mechanical properties of the host rocks that depend on their fabric and mineralogical composition: subvertical fractures in mudstones and limestones show steeper dips than those within the more clayey intervals; bedding-parallel fractures occur within organic-rich claystones and along the boundaries between different lithologies; tuffites and radiolaria-bearing siliceous mudstones are more brittle and show denser nets of fractures or wider mineral apertures; and, fracture refraction is observed at competence contrast or around spherical concretions. The fault and fracture mineralization itself is prone to the heterogenity of the rock profile. Thus, fractures infilled with calcite occur in all types of the studied rocks, but mineral growth is syntaxial within marly mudstones because of chemical uniformity, and antitaxial within sillicous mudstones. Fractures infilled with quartz are

  6. Estimation of fluid flow and mass transport properties in a natural fracture using laboratory testing system on mass transport in fractured rock (LABROCK)

    Energy Technology Data Exchange (ETDEWEB)

    Yoshino, Naoto; Uchida, Masahiro [Japan Nuclear Cycle Development Inst., Tokai Works, Tokai, Ibaraki (Japan); Satou, Hisashi [Inspection Development Company Ltd., Tokai, Ibaraki (Japan)

    2003-03-01

    The understanding of mass transport and fluid flow properties in natural rock fractures is important for safety assessment of geological disposal of high level nuclear waste. The authors developed advanced tracer test equipment in which a 50-cm cubic scale rock sample was feasible. The mass transport and fluid flow properties in a single fracture were also examined. The relation among hydraulic, transport and mass balance apertures of a natural single fracture were obtained. Heterogeneity of the aperture distribution was evident, as was the possibility of some major flow line perpendicular to the flow direction. Additionally, the relation between normal stress and each aperture was also obtained by loading normal stress on the fracture. In future, measuring the aperture distribution and establishing the model considering fluid flow and mass transport properties in natural rock fractures will be conducted. (author)

  7. Numerical study on transient flow in the deep naturally fractured reservoir with high pressure

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    According to the experimental results and the characteristics of the pressure-sensitive fractured formation, a transient flow model is developed for the deep naturally-fractured reservoirs with different outer boundary conditions. The finite element equations for the model are derived. After generating the unstructured grids in the solution regions, the finite element method is used to calculate the pressure type curves for the pressure-sensitive fractured reservoir with different outer boundaries, such as the infinite boundary, circle boundary and combined linear boundaries, and the characteristics of the type curves are comparatively analyzed. The effects on the pressure curves caused by pressure sensitivity module and the effective radius combined parameter are determined, and the method for calculating the pressure-sensitive reservoir parameters is introduced. By analyzing the real field case in the high temperature and pressure reservoir, the perfect results show that the transient flow model for the pressure-sensitive fractured reservoir in this paper is correct.

  8. Numerical study on transient flow in the deep naturally fractured reservoir with high pressure

    Institute of Scientific and Technical Information of China (English)

    LIU YueWu; CHEN WeiLiang; LIU QingQuan

    2009-01-01

    According to the experimental results and the characteristics of the pressure-sensitive fractured for-mation, a transient flow model is developed for the deep naturally-fractured reservoirs with different outer boundary conditions. The finite element equations for the model are derived. After generating the unstructured grids in the solution regions, the finite element method is used to calculate the pressure type curves for the pressure-eensitive fractured reservoir with different outer boundaries, such as the infinite boundary, circle boundary and combined linear boundaries, and the characteristics of the type curves are comparatively analyzed. The effects on the pressure curves caused by pressure sensitivity module and the effective radius combined parameter are determined, and the method for calculating the pressure-sensitive reservoir parameters is introduced. By analyzing the real field case in the high temperature end pressure reservoir, the perfect results show that the transient flow model for the pressure-sensitive fractured reservoir in this paper is correct.

  9. Natural and Induced Fracture Diagnostics from 4-D VSP Low Permeability Gas Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Mark E. Willis; Daniel R. Burns; M. Nafi Toksoz

    2008-09-30

    Tight gas sand reservoirs generally contain thick gas-charged intervals that often have low porosity and very low permeability. Natural and induced fractures provide the only means of production. The objective of this work is to locate and characterize natural and induced fractures from analysis of scattered waves recorded on 4-D (time lapse) VSP data in order to optimize well placement and well spacing in these gas reservoirs. Using model data simulating the scattering of seismic energy from hydraulic fractures, we first show that it is possible to characterize the quality of fracturing based upon the amount of scattering. In addition, the picked arrival times of recorded microseismic events provide the velocity moveout for isolating the scattered energy on the 4-D VSP data. This concept is applied to a field dataset from the Jonah Field in Wyoming to characterize the quality of the induced hydraulic fractures. The time lapse (4D) VSP data from this field are imaged using a migration algorithm that utilizes shot travel time tables derived from the first breaks of the 3D VSPs and receiver travel time tables based on the microseismic arrival times and a regional velocity model. Four azimuthally varying shot tables are derived from picks of the first breaks of over 200 VSP records. We create images of the fracture planes through two of the hydraulically fractured wells in the field. The scattered energy shows correlation with the locations of the microseismic events. In addition, the azimuthal scattering is different from the azimuthal reflectivity of the reservoir, giving us more confidence that we have separated the scattered signal from simple formation reflectivity. Variation of the scattered energy along the image planes suggests variability in the quality of the fractures in three distinct zones.

  10. Natural time analysis of critical phenomena: The case of pre-fracture electromagnetic emissions

    Energy Technology Data Exchange (ETDEWEB)

    Potirakis, S. M. [Department of Electronics, Technological Education Institute (TEI) of Piraeus, 250 Thivon and P. Ralli, Aigaleo, Athens GR-12244 (Greece); Karadimitrakis, A. [Department of Physics, Section of Electronics, Computers, Telecommunications and Control, University of Athens, Panepistimiopolis, Zografos, Athens GR-15784 (Greece); Eftaxias, K. [Department of Physics, Section of Solid State Physics, University of Athens, Panepistimiopolis, Zografos, Athens GR-15784 (Greece)

    2013-06-15

    Criticality of complex systems reveals itself in various ways. One way to monitor a system at critical state is to analyze its observable manifestations using the recently introduced method of natural time. Pre-fracture electromagnetic (EM) emissions, in agreement to laboratory experiments, have been consistently detected in the MHz band prior to significant earthquakes. It has been proposed that these emissions stem from the fracture of the heterogeneous materials surrounding the strong entities (asperities) distributed along the fault, preventing the relative slipping. It has also been proposed that the fracture of heterogeneous material could be described in analogy to the critical phase transitions in statistical physics. In this work, the natural time analysis is for the first time applied to the pre-fracture MHz EM signals revealing their critical nature. Seismicity and pre-fracture EM emissions should be two sides of the same coin concerning the earthquake generation process. Therefore, we also examine the corresponding foreshock seismic activity, as another manifestation of the same complex system at critical state. We conclude that the foreshock seismicity data present criticality features as well.

  11. IMPACT OF HYDRAULIC FRACTURING ON THE QUALITY OF NATURAL WATERS

    Directory of Open Access Journals (Sweden)

    Wojciech Cel

    2017-03-01

    Full Text Available Poland, due to the estimated shale gas deposits amounting to 346-768 billion m3 has become one of the most attractive regions for shale gas exploration in Europe. Throughout the period 2010-2015, 72 exploratory drillings have been made (as of 4.01.2016 while hydraulic fracturing was carried out 25 times. Employing new drilling and shale gas prospecting technologies raises a question pertaining to their impact on the environment. The number of chemical compounds used (approximately 2000 for the production of new technological fluids may potentially pollute the environment. The fact that the composition of these fluids remains undisclosed hinders the assessment of their impact on the environment and devising optimal methods for managing this type of waste. The presented work indicates the chemical compounds which may infiltrate to groundwater, identified on the basis of technological fluids characteristics, as well as the review of studies pertaining to their impact on potable water carried out in the United States. The study focused on marking heavy metals, calcium, sodium, magnesium, potassium, chlorides and sulphates in the surface waters collected in proximity of Lewino well.

  12. Permeability Evolution in Natural Fractures Subject to Cyclic Loading and Gouge Formation

    Science.gov (United States)

    Vogler, Daniel; Amann, Florian; Bayer, Peter; Elsworth, Derek

    2016-09-01

    Increasing fracture aperture by lowering effective normal stress and by inducing dilatant shearing and thermo-elastic effects is essential for transmissivity increase in enhanced geothermal systems. This study investigates transmissivity evolution for fluid flow through natural fractures in granodiorite at the laboratory scale. Processes that influence transmissivity are changing normal loads, surface deformation, the formation of gouge and fracture offset. Normal loads were varied in cycles between 1 and 68 MPa and cause transmissivity changes of up to three orders of magnitude. Similarly, small offsets of fracture surfaces of the order of millimeters induced changes in transmissivity of up to three orders of magnitude. During normal load cycling, the fractures experienced significant surface deformation, which did not lead to increased matedness for most experiments, especially for offset fractures. The resulting gouge material production may have caused clogging of the main fluid flow channels with progressing loading cycles, resulting in reductions of transmissivity by up to one order of magnitude. During one load cycle, from low to high normal loads, the majority of tests show hysteretic behavior of the transmissivity. This effect is stronger for early load cycles, most likely when surface deformation occurs, and becomes less pronounced in later cycles when asperities with low asperity strength failed. The influence of repeated load cycling on surface deformation is investigated by scanning the specimen surfaces before and after testing. This allows one to study asperity height distribution and surface deformation by evaluating the changes of the standard deviation of the height, distribution of asperities and matedness of the fractures. Surface roughness, as expressed by the standard deviation of the asperity height distribution, increased during testing. Specimen surfaces that were tested in a mated configuration were better mated after testing, than

  13. Groundwater flow through a natural fracture. Flow experiments and numerical modelling

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, Erik [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept of Geology

    1997-09-01

    Groundwater flow and transport play an important role not only for groundwater exploration but also in environmental engineering problems. This report considers how the hydraulic properties of fractures in crystalline rock depend on the fracture aperture geometry. Different numerical models are discussed and a FDM computer code for two- and three- dimensional flow-modelling has been developed. Different relations between the cells in the model are tested and compared with results in the literature. A laboratory experimental work has been done to carry out flow experiments and aperture measurements on the same specimen of a natural fracture. The drilled core sample had fractures parallel to the core axis and was placed inside a biaxial cell during the experiments. The water pressure gradient and the compression stress were varied during the experiments and also a tracer test was done. After the flow experiments, the aperture distribution for a certain compression was measured by injecting an epoxy resin into the fracture. The thickness of the resin layer was then studied in saw cut sections of the sample. The results from the experiments were used to validate numerical and analytical models, based on aperture distribution, for flow and transport simulations. In the disturbed zone around a drift both water and air are present in the fractures. The gas will go to the most wide part of the fracture because the capillarity and the conductivity decrease. The dependence of the effective conductivity on the variance of the conductivity and the effect of extinction of highly conductive cells has also been studied. A discussion of how gas in fractures around a drift can cause a skin effect is modelled and an example is given of what a saturation depending on the magnitude of the flow causes. 25 refs, 17 tabs, 43 figs.

  14. Natural processes as means to create local connection

    DEFF Research Database (Denmark)

    Sjøstedt, Victoria

    2010-01-01

    as a sensitive reading and response to a site’s topography, hydrology, climate and ecology. The paper is based on a study of Chinese vernacular settlements and a series of explorative drawing proposals for a new residential neighbourhood in the outskirts of the Chinese city Wuhan. Natural processes are revealed...... and utilized conceptually within the Wuhan project by mapping-techniques and environmental simulation software. The result gives implications concerning method development for architects as how to develop design concepts based on natural process thinking. Furthermore, the result shows that natural processes...... act as a viable strategy to identify and develop inherent qualities of an existing site. Natural processes, neighbourhood planning, vernacular landscapes, environmental practice, urban strategy...

  15. Oil recovery from naturally fractured reservoirs by steam injection methods. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Reis, J.C.; Miller, M.A.

    1995-05-01

    Oil recovery by steam injection is a proven, successful technology for nonfractured reservoirs, but has received only limited study for fractured reservoirs. Preliminary studies suggest recovery efficiencies in fractured reservoirs may be increased by as much as 50% with the application of steam relative to that of low temperature processes. The key mechanisms enhancing oil production at high temperature are the differential thermal expansion between oil and the pore volume, and the generation of gases within matrix blocks. Other mechanisms may also contribute to increased production. These mechanisms are relatively independent of oil gravity, making steam injection into naturally fractured reservoirs equally attractive to light and heavy oil deposits. The objectives of this research program are to quantify the amount of oil expelled by these recovery mechanisms and to develop a numerical model for predicting oil recovery in naturally fractured reservoirs during steam injection. The experimental study consists of constructing and operating several apparatuses to isolate each of these mechanisms. The first measures thermal expansion and capillary imbibition rates at relatively low temperature, but for various lithologies and matrix block shapes. The second apparatus measures the same parameters, but at high temperatures and for only one shape. A third experimental apparatus measures the maximum gas saturations that could build up within a matrix block. A fourth apparatus measures thermal conductivity and diffusivity of porous media. The numerical study consists of developing transfer functions for oil expulsion from matrix blocks to fractures at high temperatures and incorporating them, along with the energy equation, into a dual porosity thermal reservoir simulator. This simulator can be utilized to make predictions for steam injection processes in naturally-fractured reservoirs. Analytical models for capillary imbibition have also been developed.

  16. The IPBES conceptual framework — connecting nature and people

    CSIR Research Space (South Africa)

    Diaz, S

    2015-06-01

    Full Text Available , such as natural, social and engineering scientists, policy-makers at different levels, and decision- makers in different sectors of society. Addresses 1 Instituto Multidisciplinario de Biologı´a Vegetal (IMBIV-CONICET) and FCEFyN, Universidad Nacional de Co...´noma de Me´xico, Mexico DF, Mexico 4Departamento de Biologia Vegetal, Instituto de Biologia, Universidade Estadual de Campinas, UNICAMP, Campinas, Brazil 5 Commonwealth Scientific and Industrial Research Organization, Canberra, Australia. Present address...

  17. 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.

  18. Approximating natural connectivity of scale-free networks based on largest eigenvalue

    Science.gov (United States)

    Tan, S.-Y.; Wu, J.; Li, M.-J.; Lu, X.

    2016-06-01

    It has been recently proposed that natural connectivity can be used to efficiently characterize the robustness of complex networks. The natural connectivity has an intuitive physical meaning and a simple mathematical formulation, which corresponds to an average eigenvalue calculated from the graph spectrum. However, as a network model close to the real-world system that widely exists, the scale-free network is found difficult to obtain its spectrum analytically. In this article, we investigate the approximation of natural connectivity based on the largest eigenvalue in both random and correlated scale-free networks. It is demonstrated that the natural connectivity of scale-free networks can be dominated by the largest eigenvalue, which can be expressed asymptotically and analytically to approximate natural connectivity with small errors. Then we show that the natural connectivity of random scale-free networks increases linearly with the average degree given the scaling exponent and decreases monotonically with the scaling exponent given the average degree. Moreover, it is found that, given the degree distribution, the more assortative a scale-free network is, the more robust it is. Experiments in real networks validate our methods and results.

  19. Connectivity of nature in the Nordic countries (CONNOR)

    DEFF Research Database (Denmark)

    2008-01-01

    Changes in the spatial structure of habitats, such as declining habitat ar-eas and the spatial fragmentation of habitats are, together with a decreas-ing habitat quality, a major pressure on biological diversity. Spatial indi-cators can function as a suitable tool for the assessment of habitat...... and needed research for the integration of spatial indicators in nature monitoring in the Nordic coun-tries. This report sums up the workshop results. Presentations given throughout the workshop clearly indicate the rele-vance of spatial structure of habitats for biological diversity. Furthermore, a variety...... of approaches exist, where spatial indicators have been success-fully applied to describe state and change in biological diversity. In order to reasonably describe biological diversity, spatial indicators must be based on specific knowledge on species' requirements for quality and spatial structure of habitats...

  20. Brain dynamics during natural viewing conditions--a new guide for mapping connectivity in vivo.

    Science.gov (United States)

    Bartels, Andreas; Zeki, Semir

    2005-01-15

    We describe here a new way of obtaining maps of connectivity in the human brain based on interregional correlations of blood oxygen level-dependent (BOLD) signal during natural viewing conditions. We propose that anatomical connections are reflected in BOLD signal correlations during natural brain dynamics. This may provide a powerful approach to chart connectivity, more so than that based on the 'resting state' of the human brain, and it may complement diffusion tensor imaging. Our approach relies on natural brain dynamics and is therefore experimentally unbiased and independent of hypothesis-driven, specialized stimuli. It has the advantage that natural viewing leads to considerably stronger cortical activity than rest, thus facilitating detection of weaker connections. To validate our technique, we used functional magnetic resonance imaging (fMRI) to record BOLD signal while volunteers freely viewed a movie that was interrupted by resting periods. We used independent component analysis (ICA) to segregate cortical areas before characterizing the dynamics of their BOLD signal during free viewing and rest. Natural viewing and rest each revealed highly specific correlation maps, which reflected known anatomical connections. Examples are homologous regions in visual and auditory cortices in the two hemispheres and the language network consisting of Wernicke's area, Broca's area, and a premotor region. Correlations between regions known to be directly connected were always substantially higher than between nonconnected regions. Furthermore, compared to rest, natural viewing specifically increased correlations between anatomically connected regions while it decreased correlations between nonconnected regions. Our findings therefore demonstrate that natural viewing conditions lead to particularly specific interregional correlations and thus provide a powerful environment to reveal anatomical connectivity in vivo.

  1. The Nature of the Tensile Fracture in Austempered Ductile Iron with Dual Matrix Microstructure

    Science.gov (United States)

    Kilicli, Volkan; Erdogan, Mehmet

    2010-02-01

    The tensile fracture characteristics of austempered ductile irons with dual matrix structures and different ausferrite volume fractions have been studied for an unalloyed ductile cast iron containing (in wt.%) 3.50 C, 2.63 Si, 0.318 Mn, and 0.047 Mg. Specimens were intercritically austenitized (partially austenitized) in two phase region (α + γ) at various temperatures for 20 min and then quenched into a salt bath held at austempering temperature of 365 °C for various times and then air cooled to room temperature to obtain various ausferrite volume fractions. Conventionally austempered specimens with fully ausferritic matrix and unalloyed as-cast specimens having fully ferritic structures were also tested for comparison. In dual matrix structures, results showed that the volume fraction of proeutectoid ferrite, new (epitaxial) ferrite, and ausferrite [bainitic ferrite + high-carbon austenite (stabilized or transformed austenite)] can be controlled to influence the strength and ductility. Generally, microvoids nucleation is initiated at the interface between the graphite nodules and the surrounding ferritic structure and at the grain boundary junctions in the fully ferritic microstructure. Debonding of the graphite nodules from the surrounding matrix structure was evident. The continuity of the ausferritic structure along the intercellular boundaries plays an important role in determining the fracture behavior of austempered ductile iron with different ausferrite volume fractions. The different fracture mechanisms correspond to the different levels of ausferrite volume fractions. With increasing continuity of the ausferritic structure, fracture pattern changed from ductile to moderate ductile nature. On the other hand, in the conventionally austempered samples with a fully ausferritic structure, the fracture mode was a mixture of quasi-cleavage and a dimple pattern. Microvoid coalescence was the dominant form of fracture in all structures.

  2. Optimal networks of nature reserves can be found through eigenvalue perturbation theory of the connectivity matrix.

    Science.gov (United States)

    Jacobi, Martin Nilsson; Jonsson, Per R

    2011-07-01

    Conservation and management of natural resources and biodiversity need improved criteria to select functional networks of protected areas. The connectivity within networks due to dispersal is rarely considered, partly because it is unclear how connectivity information can be included in the selection of protected areas. We present a novel and general method that applies eigenvalue perturbation theory (EPT) to select optimum networks of protected areas based on connectivity. At low population densities, characteristic of threatened populations, this procedure selects networks that maximize the growth rate of the overall network. This method offers an improved link between connectivity and metapopulation dynamics. Our framework is applied to connectivities estimated for marine larvae and demonstrates that, for open populations, the best strategy is to protect areas acting as both strong donors and recipients of recruits. It should be possible to implement an EPT framework for connectivity analysis into existing holistic tools for design of protected areas.

  3. Fractured inlet connecting tube of the flat bottom flushing device of a posterior fossa cystoperitoneal shunt

    Directory of Open Access Journals (Sweden)

    Abbas Amirjamshidi

    2015-01-01

    Conclusion: Awareness of the possibility of fracture site in the junction of the inlet connector of flat bottom shunt systems is warranted and can be diagnosed by three-dimensional computed tomography (3D CT imaging without performing shunt series study.

  4. Modelling Orthorhombic Anisotropic Effects for Reservoir Fracture Characterization of a Naturally Fractured Tight Carbonate Reservoir, Onshore Texas, USA

    Science.gov (United States)

    Osinowo, Olawale Olakunle; Chapman, Mark; Bell, Rebecca; Lynn, Heloise B.

    2017-09-01

    In this study we present a step-by-step theoretical modelling approach, using established seismic wave propagation theories in anisotropic media, to generate unique anisotropic reflection patterns observed from three-dimensional pure-mode pressure (3D-PP), full-azimuth and full-offset seismic reflection data acquired over a naturally fractured tight carbonate field, onshore Texas, USA. Our aim is to gain an insight into the internal structures of the carbonate reservoir responsible for the observed anisotropic reflection patterns. From the generated model we were able to establish that the observed field seismic reflection patterns indicate azimuthal anisotropy in the form of crack induced shear-wave splitting and variation in P-wave velocity with offset and azimuth. Amplitude variation with azimuth (AVAZ) analysis also confirmed multi-crack sets induced anisotropy which is characteristic of orthorhombic symmetry, evident as multiple bright and dim-amplitude azimuth directions as well as complete reversal of bright-amplitude to dim-amplitude azimuth direction as the angle of incidence increases from near (≤15°) to mid (≥30°) offsets. Finally, we fitted the generated P-wave velocity into an ellipse to determine the intensity and orientation (N26E) of the open crack set as well as the direction of the minimum in situ stress axis (N116E) within the reservoir. The derived information served as an aid for the design of horizontal well paths that would intercept open fractures and ensure production optimization of the carbonate reservoir, which was on production decline despite reservoir studies that indicate un-depleted reserves.

  5. A modeling and numerical algorithm for thermoporomechanics in multiple porosity media for naturally fractured reservoirs

    Science.gov (United States)

    Kim, J.; Sonnenthal, E. L.; Rutqvist, J.

    2011-12-01

    Rigorous modeling of coupling between fluid, heat, and geomechanics (thermo-poro-mechanics), in fractured porous media is one of the important and difficult topics in geothermal reservoir simulation, because the physics are highly nonlinear and strongly coupled. Coupled fluid/heat flow and geomechanics are investigated using the multiple interacting continua (MINC) method as applied to naturally fractured media. In this study, we generalize constitutive relations for the isothermal elastic dual porosity model proposed by Berryman (2002) to those for the non-isothermal elastic/elastoplastic multiple porosity model, and derive the coupling coefficients of coupled fluid/heat flow and geomechanics and constraints of the coefficients. When the off-diagonal terms of the total compressibility matrix for the flow problem are zero, the upscaled drained bulk modulus for geomechanics becomes the harmonic average of drained bulk moduli of the multiple continua. In this case, the drained elastic/elastoplastic moduli for mechanics are determined by a combination of the drained moduli and volume fractions in multiple porosity materials. We also determine a relation between local strains of all multiple porosity materials in a gridblock and the global strain of the gridblock, from which we can track local and global elastic/plastic variables. For elastoplasticity, the return mapping is performed for all multiple porosity materials in the gridblock. For numerical implementation, we employ and extend the fixed-stress sequential method of the single porosity model to coupled fluid/heat flow and geomechanics in multiple porosity systems, because it provides numerical stability and high accuracy. This sequential scheme can be easily implemented by using a porosity function and its corresponding porosity correction, making use of the existing robust flow and geomechanics simulators. We implemented the proposed modeling and numerical algorithm to the reaction transport simulator

  6. Simulation of petroleum recovery in naturally fractured reservoirs: physical process representation

    Energy Technology Data Exchange (ETDEWEB)

    Paiva, Hernani P.; Miranda Filho, Daniel N. de [Petroleo Brasileiro S.A. (PETROBRAS), Rio de Janeiro, RJ (Brazil); Schiozer, Denis J. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil)

    2012-07-01

    The naturally fractured reservoir recovery normally involves risk especially in intermediate to oil wet systems because of the simulations poor efficiency results under waterflood displacement. Double-porosity models are generally used in fractured reservoir simulation and have been implemented in the major commercial reservoir simulators. The physical processes acting in petroleum recovery are represented in double-porosity models by matrix-fracture transfer functions, therefore commercial simulators have their own implementations, and as a result different kinetics and final recoveries are attained. In this work, a double porosity simulator was built with Kazemi et al. (1976), Sabathier et al. (1998) and Lu et al. (2008) transfer function implementations and their recovery results have been compared using waterflood displacement in oil-wet or intermediate-wet systems. The results of transfer function comparisons have showed recovery improvements in oil-wet or intermediate-wet systems under different physical processes combination, particularly in fully discontinuous porous medium when concurrent imbibition takes place, coherent with Firoozabadi (2000) experimental results. Furthermore, the implemented transfer functions, related to a double-porosity model, have been compared to double-porosity commercial simulator model, as well a discrete fracture model with refined grid, showing differences between them. Waterflood can be an effective recovery method even in fully discontinuous media for oil-wet or intermediate-wet systems where concurrent imbibition takes place with high enough pressure gradients across the matrix blocks. (author)

  7. The detection and characterization of natural fractures using P-wave reflection data, multicomponent VSP, borehole image logs and the in-situ stress field determination

    Energy Technology Data Exchange (ETDEWEB)

    Hoekstra, P. [Coleman Research Corp., Orlando, FL (United States)

    1995-04-01

    The objectives of this project are to detect and characterize fractures in a naturally fractured tight gas reservoir, using surface seismic methods, borehole imaging logs, and in-situ stress field data. Further, the project aims to evaluate the various seismic methods as to their effectiveness in characterizing the fractures, and to formulate the optimum employment of the seismic methods as regards fracture characterization.

  8. Nature connection, outdoor play, and environmental stewardship in residential environmental education

    Science.gov (United States)

    Andrejewski, Robert G.

    A lack of exposure to the natural world has led to a generation of children disconnected from nature. This phenomenon has profound negative implications for the physical and psychological well being of today's youth. Residential environmental education provides one avenue to connect children to nature. One purpose of this study was to investigate the role of Outdoor School, a residential environmental education program, on ecological knowledge, children's connection to nature, school belonging, outdoor play attitude, environmental stewardship attitude, outdoor play behavior, and environmental stewardship behavior, as reported by participants. A quasi-experimental research design was utilized in the study. A total of 228 fifth grade students (156 treatment, 72 control) from central Pennsylvania participated. The results of the program evaluation indicated that Outdoor School was successful in achieving significant, positive gains in the areas of ecological knowledge, connection to nature, outdoor play behavior, and environmental stewardship behavior. No change was found from pretest to post-test in outdoor play attitudes, environmental stewardship attitudes, and school belonging. Additionally, the study addressed gaps in the literature regarding the relationship between connection to nature, environmental stewardship, and outdoor play using two different approaches. An adaptation of the Theory of Planned Behavior (TPB) was used to predict outdoor play behavior in children. In this model, favorable attitudes, subjective norms, and perceived behavioral control lead to intentions to perform a given behavior. Intention to perform the behavior is the best predictor for behavior performance. For this study, participants' feeling of connection to nature was added as an affective independent variable. This model explained 45% of the variance in outdoor play. The hypothesis that a connection to nature would be a significant predictor of both attitudes toward outdoor play was

  9. Natural and Artificial Connections between Atoll Islets in the Pacific, Their Process and Environmental Impact

    Institute of Scientific and Technical Information of China (English)

    XUE Chunting; Russell Howorth

    2003-01-01

    Three types of natural connection between atoll islets are described. Causeway, as an artificial way of connecting islets, makes a connection to be completed in a few months. In this case shore adjustment becomes more vigorous than that in natural conditions, resulting in lagoon shore erosion. A causeway without short bridges or culverts should be built close to the lagoon shore to reduce lagoon shore erosion. A causeway-crossing channel assemblage is the worst type among all of the connection engineering constructions because the crossing channel traps sediment and further transports it out of the channel, resulting in long period coastal erosion. Reforming Nippon Causeway in Tarawa Atoll, Kiribati by simple means will stop sand loss, reduce shore erosion and greatly upgrade its stability.

  10. Effect of the state of internal boundaries on granite fracture nature under quasi-static compression

    Science.gov (United States)

    Damaskinskaya, E. E.; Panteleev, I. A.; Kadomtsev, A. G.; Naimark, O. B.

    2017-05-01

    Based on an analysis of the spatial distribution of hypocenters of acoustic emission signal sources and an analysis of the energy distributions of acoustic emission signals, the effect of the liquid phase and a weak electric field on the spatiotemporal nature of granite sample fracture is studied. Experiments on uniaxial compression of granite samples of natural moisture showed that the damage accumulation process is twostage: disperse accumulation of damages is followed by localized accumulation of damages in the formed macrofracture nucleus region. In energy distributions of acoustic emission signals, this transition is accompanied by a change in the distribution shape from exponential to power-law. Granite water saturation qualitatively changes the damage accumulation nature: the process is delocalized until macrofracture with the exponential energy distribution of acoustic emission signals. An exposure to a weak electric field results in a selective change in the damage accumulation nature in the sample volume.

  11. Natural fracturing of rocks: application to the Ahnet basin (Algeria); Fracturation naturelle des roches: application au bassin de l`Ahnet (Algerie)

    Energy Technology Data Exchange (ETDEWEB)

    Badsi, M.

    1998-07-06

    In the Ahnet basin, the production seems to be unrelated to lithological variations in the reservoirs. In these large anticline structures, located in the central Ahnet basin, the presence of gas has been proven, but only a few production wells have been moderately successful. This inconsistency is probably related to the spatial distribution of fracturing throughout the reservoir. In order to investigate several hypothesis, we used several approach to solve problems posed by the interpreter: namely understanding the deformation process, predicting the fractured zones and building the discrete model of fracture network. This approach combines several methods, including sand box modelling, numerical modelling and Statistics rules, often related with fractal behaviour of faults families, have been used for extrapolating observations from seismic or from wells. The numerical tools and sand box analysis have allowed us to answer to the questions related to the formation of this large anticlines in the Ahnet basin and suggest a probable origin of the variation in the spatial distribution of natural fractures. The deterministic predictions of small-scale faults use probabilistic approaches for spatial interpolation assuming implicitly relationship between detected large faults and unresolved small faults. The statistical modelling is used to carry out analysis of the spatial variation of mean fracture attributes at the global scale (a few kilometers) and a 3D stochastic modelling of the fracture system at the local scale (a few ten of meters). (author) 139 refs.

  12. Measurement of Residual Stress in a Welded Branch Connection and Effects on Fracture Behaviour

    Science.gov (United States)

    Law, M.; Luzin, V.; Kirstein, O.

    2010-11-01

    The branch analysed in this paper was not post weld heat treated, resulting in significant residual stresses. Assessment codes assume these to be at, or close to, yield. An integrity assessment of a welded branch connection was carried out using these high assumed residual stresses. The weld then had residual stresses determined by neutron diffraction, performed using ANSTO's residual stress diffractometer, Kowari. The maximum measured residual stress (290 MPa or 60% of yield) was much lower than the yield value assumed by assessment codes. Reanalysing with the actual residual stresses almost doubled the critical crack size, increasing the safety of the connection.

  13. Connecting to Nature at the Zoo: Implications for Responding to Climate Change

    Science.gov (United States)

    Clayton, Susan; Luebke, Jerry; Saunders, Carol; Matiasek, Jennifer; Grajal, Alejandro

    2014-01-01

    Societal response to climate change has been inadequate. A perception that the issue is both physically and temporally remote may reduce concern; concern may also be affected by the political polarization surrounding the issue in the USA. A feeling of connection to nature or to animals may increase personal relevance, and a supportive social…

  14. Connecting to Nature at the Zoo: Implications for Responding to Climate Change

    Science.gov (United States)

    Clayton, Susan; Luebke, Jerry; Saunders, Carol; Matiasek, Jennifer; Grajal, Alejandro

    2014-01-01

    Societal response to climate change has been inadequate. A perception that the issue is both physically and temporally remote may reduce concern; concern may also be affected by the political polarization surrounding the issue in the USA. A feeling of connection to nature or to animals may increase personal relevance, and a supportive social…

  15. The constraints of connecting children with nature--A research literature review

    Science.gov (United States)

    Ponds, Phadrea D.; Schuster, Rudy M.

    2011-01-01

    Reports or research investigations studying children in nature are rapidly expanding and increasingly diverse. This document reports a review of a particular part of this field-studies of constraints to recreation and participation in environmental and outdoor recreation programs. The findings result from a review of more than 125 journal articles, books, and reports that were published between 1980 and 2009. This report discusses how the current information concerning constraints to participation can be understood in terms of four concentrations or foci of work generated in this particular field of study. These foci, which are all well established in the literature, are (1) intrapersonal, interpersonal, and structural constraints, (2) significant life experiences, (3) environmental attitudes, values and beliefs, and (4) environmental behaviors. The recent research associated with each of these research areas is discussed in successive sections of the review. Overall, this review found that the research on constraints that inhibit children's connection to nature is less diverse in terms of methodological and theoretical approaches than is the research into the broader outdoor recreation research field within which it is situated. This review focused on the issue of connecting children with nature, but examples from studies using adults to understand childhood experiences and recreation preferences were used because there are relatively few peer-reviewed articles showing the theoretical or empirical connection of children and nature. In some cases, broader empirical studies were used to connect with larger themes (that is, environmental attitudes, beliefs, and values).

  16. Fostering Connections to Nature -- Strategies for Community College Early Childhood Teachers

    Science.gov (United States)

    Murphy, Debra

    2017-01-01

    How can early childhood teacher educators at the community college level create opportunities for their students to explore and relate to the natural world? This article discusses three learning opportunities in an early childhood associate-degree program that foster connections between preservice and inservice early childhood teachers and nature…

  17. Water usage for natural gas production through hydraulic fracturing in the United States from 2008 to 2014.

    Science.gov (United States)

    Chen, Huan; Carter, Kimberly E

    2016-04-01

    Hydraulic fracturing has promoted the exploitation of shale oil and natural gas in the United States (U.S.). However, the large amounts of water used in hydraulic fracturing may constrain oil and natural gas production in the shale plays. This study surveyed the amounts of freshwater and recycled produced water used to fracture wells from 2008 to 2014 in Arkansas, California, Colorado, Kansas, Louisiana, Montana, North Dakota, New Mexico, Ohio, Oklahoma, Pennsylvania, Texas, West Virginia, and Wyoming. Results showed that the annual average water volumes used per well in most of these states ranged between 1000 m(3) and 30,000 m(3). The highest total amount of water was consumed in Texas with 457.42 Mm(3) of water used to fracture 40,521 wells, followed by Pennsylvania with 108.67 Mm(3) of water used to treat 5127 wells. Water usages ranged from 96.85 Mm(3) to 166.10 Mm(3) annually in Texas from 2012 to 2014 with more than 10,000 wells fractured during that time. The percentage of water used for hydraulic fracturing in each state was relatively low compared to water usages for other industries. From 2009 to 2014, 6.55% (median) of the water volume used in hydraulic fracturing contained recycled produced water or recycled hydraulic fracturing wastewater. 10.84% (median) of wells produced by hydraulic fracturing were treated with recycled produced water. The percentage of wells where recycled wastewater was used was lower, except in Ohio and Arkansas, where more than half of the wells were fractured using recycled produced water. The median recycled wastewater volume in produced wells was 7127 m(3) per well, more than half the median value in annual water used per well 11,259 m(3). This indicates that, for wells recycling wastewater, more than half of their water use consisted of recycled wastewater.

  18. Relating functional connectivity in V1 neural circuits and 3D natural scenes using Boltzmann machines

    Science.gov (United States)

    Zhang, Yimeng; Li, Xiong; Samonds, Jason M.

    2015-01-01

    Bayesian theory has provided a compelling conceptualization for perceptual inference in the brain. Central to Bayesian inference is the notion of statistical priors. To understand the neural mechanisms of Bayesian inference, we need to understand the neural representation of statistical regularities in the natural environment. In this paper, we investigated empirically how statistical regularities in natural 3D scenes are represented in the functional connectivity of disparity-tuned neurons in the primary visual cortex of primates. We applied a Boltzmann machine model to learn from 3D natural scenes, and found that the units in the model exhibited cooperative and competitive interactions, forming a “disparity association field”, analogous to the contour association field. The cooperative and competitive interactions in the disparity association field are consistent with constraints of computational models for stereo matching. In addition, we simulated neurophysiological experiments on the model, and found the results to be consistent with neurophysiological data in terms of the functional connectivity measurements between disparity-tuned neurons in the macaque primary visual cortex. These findings demonstrate that there is a relationship between the functional connectivity observed in the visual cortex and the statistics of natural scenes. They also suggest that the Boltzmann machine can be a viable model for conceptualizing computations in the visual cortex and, as such, can be used to predict neural circuits in the visual cortex from natural scene statistics. PMID:26712581

  19. Connecting Children to Nature: A Multiple Case Study of Nature Center Preschools

    Science.gov (United States)

    Bailie, Patti Ensel

    2012-01-01

    Environmental degradation, childhood obesity, and aggression of youth are societal problems that appear unconnected. However, their cause (and possible solution) may be linked to a common experience--the amount and quality of time spent in the natural world. Environment based education, significant life experience research, and studies involving…

  20. Stress analysis and optimization of Nd:YAG pulsed laser processing of notches for fracture splitting of a C70S6 connecting rod

    Energy Technology Data Exchange (ETDEWEB)

    Kou, Shuqing; Gao, Yan; Zhao, Yong; Lin, Baojun [Jilin University, Changchun (China)

    2017-05-15

    The pulsed laser pre-processing of a notch as the fracture initiation source for the splitting process is the key mechanism of an advanced fracture splitting technology for C70S6 connecting rods. This study investigated the stress field of Nd:YAG pulsed laser grooving, which affects the rapid fracture initiation at the notch root and the controlled crack extension in the critical fracture splitting quality, to improve manufacturing quality. Thermal elastic-plastic incremental theory was applied to build the finite element analysis model of the stress field of pulsed laser grooving for fracture splitting based on the Rotary-Gauss body heat source. The corresponding numerical simulation of the stress field was conducted. The changes and distributions of the stress during pulsed laser grooving were examined, the influence rule of the primary technological parameters on the residual stress was analyzed, and the analysis results were validated by the corresponding cutting experiment. Results showed that the residual stress distribution was concentrated in the Heat-affected zone (HAZ) near the fracture splitting notch, which would cause micro-cracks in the HAZ. The stress state of the notch root in the fracture initiation direction was tensile stress, which was beneficial to the fracture initiation and the crack rapid extension in the subsequent fracture splitting process. However, the uneven distribution of the stress could lead to fracture splitting defects, and thus the residual stress should be lowered to a reasonable range. Decreasing the laser pulse power, increasing the processing speed, and lowering the pulse width can lower the residual stress. Along with the actual production, the reasonable main technological parameters were obtained.

  1. Relations between urban bird and plant communities and human well-being and connection to nature.

    Science.gov (United States)

    Luck, Gary W; Davidson, Penny; Boxall, Dianne; Smallbone, Lisa

    2011-08-01

    By 2050, 70% of the world's population will live in urban areas. In many cases urbanization reduces the richness and abundance of native species. Living in highly modified environments with fewer opportunities to interact directly with a diversity of native species may adversely affect residents' personal well-being and emotional connection to nature. We assessed the personal well-being, neighborhood well-being (a measure of a person's satisfaction with their neighborhood), and level of connection to nature of over 1000 residents in 36 residential neighborhoods in southeastern Australia. We modeled these response variables as a function of natural features of each neighborhood (e.g., species richness and abundance of birds, density of plants, and amount of vegetation cover) and demographic characteristics of surveyed residents. Vegetation cover had the strongest positive relations with personal well-being, whereas residents' level of connection to nature was weakly related to variation in species richness and abundance of birds and density of plants. Demographic characteristics such as age and level of activity explained the greatest proportion of variance in well-being and connection to nature. Nevertheless, when controlling for variation in demographic characteristics (examples were provided above), neighborhood well-being was positively related to a range of natural features, including species richness and abundance of birds, and vegetation cover. Demographic characteristics and how well-being was quantified strongly influenced our results, and we suggest demography and metrics of well-being must be considered when attempting to determine relations between the urban environment and human well-being. © 2011 Society for Conservation Biology.

  2. Natural environments, nature relatedness and the ecological theater: connecting satellites and sequencing to shinrin-yoku.

    Science.gov (United States)

    Craig, Jeffrey M; Logan, Alan C; Prescott, Susan L

    2016-01-13

    Recent advances in research concerning the public health value of natural environments have been remarkable. The growing interest in this topic (often housed under terms such as green and/or blue space) has been occurring in parallel with the microbiome revolution and an increased use of remote sensing technology in public health. In the context of biodiversity loss, rapid urbanization, and alarming rates of global non-communicable diseases (many associated with chronic, low-grade inflammation), discussions of natural vis-a-vis built environments are not merely fodder for intellectual curiosity. Here, we argue for increased interdisciplinary collaboration with the aim of better understanding the mechanisms-including aerobiological and epigenetic-that might help explain some of the noted positive health outcomes. It is our contention that some of these mechanisms are related to ecodiversity (i.e., the sum of biodiversity and geodiversity, including biotic and abiotic constituents). We also encourage researchers to more closely examine individual nature relatedness and how it might influence many outcomes that are at the interface of lifestyle habits and contact with ecodiversity.

  3. Sustainable Management of Flowback Water during Hydraulic Fracturing of Marcellus Shale for Natural Gas Production

    Energy Technology Data Exchange (ETDEWEB)

    Vidic, Radisav [Univ. of Pittsburgh, PA (United States)

    2015-01-24

    This study evaluated the feasibility of using abandoned mine drainage (AMD) as make- up water for the reuse of produced water for hydraulic fracturing. There is an abundance of AMD sources near permitted gas wells as documented in this study that can not only serve as makeup water and reduce the demand on high quality water resources but can also as a source of chemicals to treat produced water prior to reuse. The assessment of AMD availability for this purpose based on proximity and relevant regulations was accompanied by bench- and pilot-scale studies to determine optimal treatment to achieve desired water quality for use in hydraulic fracturing. Sulfate ions that are often present in AMD at elevated levels will react with Ba²⁺ and Sr²⁺ in produced water to form insoluble sulfate compounds. Both membrane microfiltration and gravity separation were evaluated for the removal of solids formed as a result of mixing these two impaired waters. Laboratory studies revealed that neither AMD nor barite formed in solution had significant impact on membrane filtration but that some produced waters contained submicron particles that can cause severe fouling of microfiltration membrane. Coagulation/flocculation was found to be an effective process for the removal of suspended solids and both bench- and pilot-scale studies revealed that optimal process conditions can consistently achieve the turbidity of the finished water below 5 NTU. Adjusting the blending ratio of AMD and produced water can achieve the desired effluent sulfate concentration that can be accurately predicted by chemical thermodynamics. Co-treatment of produced water and AMD will result in elevated levels of naturally occurring radioactive materials (NORM) in the solid waste generated in this process due to radium co-precipitation with barium sulfate. Laboratory studies revealed that the mobility of barite that may form in the subsurface due to the presence of sulfate in the fracturing fluid can be

  4. On some Lie groups as 5-dimensional almost contact B-metric manifolds with three natural connections

    OpenAIRE

    Ivanova, Miroslava; Manev, Hristo

    2014-01-01

    Almost contact manifolds with B-metric are considered. There are studied three natural connections (i.e. linear connections preserving the structure tensors) determined by conditions for their torsions. These connections are investigated on a family of Lie groups considered as 5-dimensional almost contact B-metric manifolds.

  5. Connecting health and natural history: a failed initiative at the American Museum of Natural History, 1909-1922.

    Science.gov (United States)

    Brown, Julie K

    2014-10-01

    In 1909, curator Charles-Edward Winslow established a department of public health in New York City's American Museum of Natural History (AMNH). Winslow introduced public health as a biological science that connected human health-the modern sciences of physiology, hygiene, and urban sanitation-to the natural history of plants and animals. This was the only time an American museum created a curatorial department devoted to public health. The AMNH's Department of Public Health comprised a unique collection of live bacterial cultures-a "Living Museum"-and an innovative plan for 15 exhibits on various aspects of health. I show how Winslow, facing opposition from AMNH colleagues, gathered scientific experts and financial support, and explain the factors that made these developments seem desirable and possible. I finish with a discussion of how the Department of Public Health met an abrupt and "inglorious end" in 1922 despite the success of its collections and exhibitions.

  6. Mechanistic study of wettability alteration using surfactants with applications in naturally fractured reservoirs.

    Science.gov (United States)

    Salehi, Mehdi; Johnson, Stephen J; Liang, Jenn-Tai

    2008-12-16

    In naturally fractured reservoirs, oil recovery from waterflooding relies on the spontaneous imbibition of water to expel oil from the matrix into the fracture system. The spontaneous imbibition process is most efficient in strongly water-wet rock where the capillary driving force is strong. In oil- or mixed-wet fractured carbonate reservoirs, however, the capillary driving force for the spontaneous imbibition process is weak, and therefore the waterflooding oil recoveries are low. The recovery efficiency can be improved by dissolving low concentrations of surfactants in the injected water to alter the wettability of the reservoir rock to a more water-wet state. This wettability alteration accelerates the spontaneous imbibition of water into matrix blocks, thereby increasing the oil recovery during waterflooding. Several mechanisms have been proposed to explain the wettability alteration by surfactants, but none have been verified experimentally. Understanding of the mechanisms behind wettability alteration could help to improve the performance of the process and aid in identification of alternative surfactants for use in field applications. Results from this study revealed that ion-pair formation and adsorption of surfactant molecules through interactions with the adsorbed crude oil components on the rock surface are the two main mechanisms responsible for the wettability alteration. Previous researchers observed that, for a given rock type, the effectiveness of wettability alteration is highly dependent upon the ionic nature of the surfactant involved. Our experimental results demonstrated that ion-pair formation between the charged head groups of surfactant molecules and the adsorbed crude oil components on rock surface was more effective in changing the rock wettability toward a more water-wet state than the adsorption of surfactant molecules as a monolayer on the rock surface through hydrophobic interaction with the adsorbed crude oil components. By comparing

  7. A natural connection on a basic class of Riemannian product manifolds

    CERN Document Server

    Gribacheva, Dobrinka

    2011-01-01

    A Riemannian manifold M with an integrable almost product structure P is called a Riemannian product manifold. Our investigations are on the manifolds (M; P; g) of the largest class of Riemannian product manifolds, which is closed with respect to the group of conformal transformations of the metric g. This class is an analogue of the class of locally conformal Kahler manifolds in almost Hermitian geometry. In the present paper we study a natural connection D on (M; P; g) (i.e. DP = Dg = 0). We find necessary and suffcient conditions the curvature tensor of D to have properties similar to the Kahler tensor in Hermitian geometry. We pay attention to the case when D has a parallel torsion.We establish that the Weyl tensors for the connection D and the Levi-Civita connection coincide as well as the invariance of the curvature tensor of D with respect to the usual conformal transformation. We consider the case when D is a at connection. We construct an example of the considered manifold by a Lie group where D is a...

  8. Statistical description of wetland hydrological connectivity to the River Murray in South Australia under both natural and regulated conditions

    Science.gov (United States)

    Robinson, Sean J.; Souter, Nicholas J.; Bean, Nigel G.; Ross, Joshua V.; Thompson, Richard M.; Bjornsson, Kjartan T.

    2015-12-01

    The effect of river regulation on the connectivity of the South Australian River Murray to its floodplain wetlands was examined using unregulated 'natural' and 'regulated' river flow data simulated between the years 1895 to 2009. A sample of 185 wetlands was used to calculate a range of connectivity statistics under both simulation scenarios. These statistics summarised the timing and duration of both connection and disconnection, as well as inundated area. Wetlands ranged from being permanently inundated, connected multiple times per year due to both small fluctuations in river level and the annual flood pulse, to flooded with diminishing frequency depending on the size of the annual flood pulse and their position on the floodplain. Under the natural scenario a wide range of wetland connectivity profiles were recorded whereas under the regulated scenario wetlands tended to be either permanently inundated or infrequently flooded. Under natural conditions wetlands that required higher flow before connecting were less frequently connected and for shorter periods. Under regulated conditions a larger proportion of wetland area was permanently connected than under natural conditions, however the annual flood pulse connected a larger area of wetlands under natural conditions. The information derived from this analysis can be used to design wetland management plans for individual wetlands within a river-wide management regime restoring lost hydrological variability.

  9. Simulation of Naturally Fractured Reservoirs. State of the Art Simulation des réservoirs naturellement fracturés. État de l’art

    Directory of Open Access Journals (Sweden)

    Lemonnier P.

    2010-04-01

    Full Text Available Naturally fractured reservoirs contain a significant amount of the world oil reserves. The production of this type of reservoirs constitutes a challenge for reservoir engineers. Use of reservoir simulators can help reservoir engineers in the understanding of the main physical mechanisms and in the choice of the best recovery process and its optimization. Significant progress has been made since the first publications on the dual-porosity concept in the sixties. This paper and the preceding one (Part 1 present the current techniques of modeling used in industrial simulators. The optimal way to predict matrix-fracture transfers at the simulator cell scale has no definite answer and various methods are implemented in industrial simulators. This paper focuses on the modeling of physical mechanisms driving flows and interactions/ exchanges within and between fracture and matrix media for a better understanding of proposed flow formula and simulation methods. Typical features of fractured reservoir numerical simulations are also described with an overview of the implementation of geomechanics effects, an application of uncertainty assessment methodology to a fractured gas reservoir and finally a presentation of a history matching methodology for fractured reservoirs. Les réservoirs naturellement fracturés contiennent une partie significative des réserves en huile mondiales. La production de ce type de réservoirs constitue un défi pour les ingénieurs de réservoir. L’utilisation des simulateurs de réservoir peut aider l’ingénieur de réservoir à mieux comprendre les principaux mécanismes physiques, à choisir le procédé de récupération le mieux adapté et à l’optimiser. Des progrès sensibles ont été réalisés depuis les premières publications sur le concept double-milieu dans les années soixante. Cet article et le précédent (Partie 1 présentent les techniques actuelles de modélisation utilisées dans les simulateurs

  10. Assessing Past Fracture Connectivity in Geothermal Reservoirs Using Clumped Isotopes: Proof of Concept in the Blue Mountain Geothermal Field, Nevada USA

    Science.gov (United States)

    Huntington, K. W.; Sumner, K. K.; Camp, E. R.; Cladouhos, T. T.; Uddenberg, M.; Swyer, M.; Garrison, G. H.

    2015-12-01

    Subsurface fluid flow is strongly influenced by faults and fractures, yet the transmissivity of faults and fractures changes through time due to deformation and cement precipitation, making flow paths difficult to predict. Here we assess past fracture connectivity in an active hydrothermal system in the Basin and Range, Nevada, USA, using clumped isotope geochemistry and cold cathodoluminescence (CL) analysis of fracture filling cements from the Blue Mountain geothermal field. Calcite cements were sampled from drill cuttings and two cores at varying distances from faults. CL microscopy of some of the cements shows banding parallel to the fracture walls as well as brecciation, indicating that the cements record variations in the composition and source of fluids that moved through the fractures as they opened episodically. CL microscopy, δ13C and δ18O values were used to screen homogeneous samples for clumped isotope analysis. Clumped isotope thermometry of most samples indicates paleofluid temperatures of around 150°C, with several wells peaking at above 200°C. We suggest that the consistency of these temperatures is related to upwelling of fluids in the convective hydrothermal system, and interpret the similarity of the clumped isotope temperatures to modern geothermal fluid temperatures of ~160-180°C as evidence that average reservoir temperatures have changed little since precipitation of the calcite cements. In contrast, two samples, one of which was associated with fault gauge observed in drill logs, record significantly cooler temperatures of 19 and 73°C and anomalous δ13C and δ18Owater values, which point to fault-controlled pathways for downwelling meteoric fluid. Finally, we interpret correspondence of paleofluid temperatures and δ18Owater values constrained by clumped isotope thermometry of calcite from different wells to suggest past connectivity of fractures among wells within the geothermal field. Results show the ability of clumped isotope

  11. Enhanced functional connectivity properties of human brains during in-situ nature experience.

    Science.gov (United States)

    Chen, Zheng; He, Yujia; Yu, Yuguo

    2016-01-01

    In this study, we investigated the impacts of in-situ nature and urban exposure on human brain activities and their dynamics. We randomly assigned 32 healthy right-handed college students (mean age = 20.6 years, SD = 1.6; 16 males) to a 20 min in-situ sitting exposure in either a nature (n = 16) or urban environment (n = 16) and measured their Electroencephalography (EEG) signals. Analyses revealed that a brief in-situ restorative nature experience may induce more efficient and stronger brain connectivity with enhanced small-world properties compared with a stressful urban experience. The enhanced small-world properties were found to be correlated with "coherent" experience measured by Perceived Restorativeness Scale (PRS). Exposure to nature also induces stronger long-term correlated activity across different brain regions with a right lateralization. These findings may advance our understanding of the functional activities during in-situ environmental exposures and imply that a nature or nature-like environment may potentially benefit cognitive processes and mental well-being.

  12. Frugivorous bats maintain functional habitat connectivity in agricultural landscapes but rely strongly on natural forest fragments.

    Directory of Open Access Journals (Sweden)

    Simon P Ripperger

    Full Text Available Anthropogenic changes in land use threaten biodiversity and ecosystem functioning by the conversion of natural habitat into agricultural mosaic landscapes, often with drastic consequences for the associated fauna. The first step in the development of efficient conservation plans is to understand movement of animals through complex habitat mosaics. Therefore, we studied ranging behavior and habitat use in Dermanura watsoni (Phyllostomidae, a frugivorous bat species that is a valuable seed disperser in degraded ecosystems. Radio-tracking of sixteen bats showed that the animals strongly rely on natural forest. Day roosts were exclusively located within mature forest fragments. Selection ratios showed that the bats foraged selectively within the available habitat and positively selected natural forest. However, larger daily ranges were associated with higher use of degraded habitats. Home range geometry and composition of focal foraging areas indicated that wider ranging bats performed directional foraging bouts from natural to degraded forest sites traversing the matrix over distances of up to three hundred meters. This behavior demonstrates the potential of frugivorous bats to functionally connect fragmented areas by providing ecosystem services between natural and degraded sites, and highlights the need for conservation of natural habitat patches within agricultural landscapes that meet the roosting requirements of bats.

  13. Enhanced functional connectivity properties of human brains during in-situ nature experience

    Directory of Open Access Journals (Sweden)

    Zheng Chen

    2016-07-01

    Full Text Available In this study, we investigated the impacts of in-situ nature and urban exposure on human brain activities and their dynamics. We randomly assigned 32 healthy right-handed college students (mean age = 20.6 years, SD = 1.6; 16 males to a 20 min in-situ sitting exposure in either a nature (n = 16 or urban environment (n = 16 and measured their Electroencephalography (EEG signals. Analyses revealed that a brief in-situ restorative nature experience may induce more efficient and stronger brain connectivity with enhanced small-world properties compared with a stressful urban experience. The enhanced small-world properties were found to be correlated with “coherent” experience measured by Perceived Restorativeness Scale (PRS. Exposure to nature also induces stronger long-term correlated activity across different brain regions with a right lateralization. These findings may advance our understanding of the functional activities during in-situ environmental exposures and imply that a nature or nature-like environment may potentially benefit cognitive processes and mental well-being.

  14. Coupling of Multiphase Flow and Geomechanics in Fractured Porous Media: Application to CO2 Leakages from Natural and Stimulated Fractures

    Science.gov (United States)

    Ezzedine, S. M.

    2015-12-01

    Leakage to the atmosphere of a significant fraction of injected CO2 would constitute a failure of a geological CO2 storage project from a greenhouse gas mitigation perspective. We present a numerical model that simulates flow and transport of CO2 into heterogeneous subsurface systems. The model, StoTran, is a flexible numerical environment that uses state-of-the-art finite element and finite volume methods and unstructured adaptive mesh refinement scheme implemented using MPI and OpenMP protocols. Multiphase flow equations and the geomechanical equations are implicitly solved and either fully or sequentially coupled. StoTran can address inverse and forward problems under deterministic or stochastic conditions. For the current study, StoTran has been used to simulate several scenarios spanning from a homogeneous single layered reservoir to heterogeneous multi-layered systems, which including cap-rock with embedded fractures, have been simulated under different operations of CO2 injection and CO2 leakages conditions. Results show the impact of the injection and leakage rates on the time evolution of the spread of the CO2 plume, its interception of the fractured cap-rock and the risk associated with the contamination of the overlaying aquifer. Spatial and temporal moments have been calculated for different, deterministic of stochastic, subsurface physical and chemical properties. Spatial moments enable assessing the extent of the region of investigation under conditions of uncertainty. Furthermore, several leakage scenarios show the intermittence behavior and development of the CO2 plume in the subsurface; its first interception with the fractures located further far from the injection well then, at a second stage, its interception with the fracture within the immediate vicinity of the injection well. We will present a remedy to CO2 leakages from the reservoir in order to enhance a long term containment of the injected CO2. This work performed under the auspices of

  15. Modelling CO2 flow in naturally fractured geological media using MINC and multiple subregion upscaling procedure

    Science.gov (United States)

    Tatomir, Alexandru Bogdan A. C.; Flemisch, Bernd; Class, Holger; Helmig, Rainer; Sauter, Martin

    2017-04-01

    Geological storage of CO2 represents one viable solution to reduce greenhouse gas emission in the atmosphere. Potential leakage of CO2 storage can occur through networks of interconnected fractures. The geometrical complexity of these networks is often very high involving fractures occurring at various scales and having hierarchical structures. Such multiphase flow systems are usually hard to solve with a discrete fracture modelling (DFM) approach. Therefore, continuum fracture models assuming average properties are usually preferred. The multiple interacting continua (MINC) model is an extension of the classic double porosity model (Warren and Root, 1963) which accounts for the non-linear behaviour of the matrix-fracture interactions. For CO2 storage applications the transient representation of the inter-porosity two phase flow plays an important role. This study tests the accuracy and computational efficiency of the MINC method complemented with the multiple sub-region (MSR) upscaling procedure versus the DFM. The two phase flow MINC simulator is implemented in the free-open source numerical toolbox DuMux (www.dumux.org). The MSR (Gong et al., 2009) determines the inter-porosity terms by solving simplified local single-phase flow problems. The DFM is considered as the reference solution. The numerical examples consider a quasi-1D reservoir with a quadratic fracture system , a five-spot radial symmetric reservoir, and a completely random generated fracture system. Keywords: MINC, upscaling, two-phase flow, fractured porous media, discrete fracture model, continuum fracture model

  16. The nature of annual lamination in flowstones from non-karstic fractures, Vinschgau (northern Italy)

    Science.gov (United States)

    Koltai, Gabriella; Spötl, Christoph; Cheng, Hai

    2016-04-01

    The Vinschgau is an inneralpine valley in the Southern Alps. The region is built up by metamorphic rocks characterised by a high degree of tectonic deformation. Although karst is not known in the Vinschgau, calcite and calcite-aragonite flowstones are deposited from supersaturated groundwater along the South-facing mountain slope as a result of strong evaporation (Spötl et al. 2002). Flowstone precipitation is strongly connected to fracture openings created by deep-seated gravitational slope deformations. The carbonate-depositing springs are part of an extended groundwater system controlled by the geometry of the deep-seated gravitational slope deformation. Although the mean residence time of the groundwater is up to several decades (Spötl et al. 2002), a few flowstones show macroscopically visible laminae whose annual origin is confirmed by U-Th dating. These laminae are composed of a darker and a lighter sublamina forming couplets whose thickness ranges from 0.2 to 2 mm. In thin section, the darker sublaminae show a higher abundance of opaque particles, whereas the light ones are inclusion-poor. Strong epifluorescence confirms the organic origin of these dark inclusions. The crystal fabric, dominated by the fascicular-optic type, shows no change across lamina boundaries. Laminated calcite shows δ18O oscillations with an amplitude of up to 1.4 permil. These oscillations are also present in unlaminated calcite, albeit at much smaller amplitude. δ13C lacks such a regular pattern in laminated samples, and only shows small variations which do not correlate with δ18O in a consistent way. Changes in δ13C show smaller amplitudes than δ18O. The extent of correlation between petrographic laminae and the stable isotopes varies both in time and space. During the late Younger Dryas darker sublaminae mostly coincide with δ18O lows, whereas in the Mid-Holocene they usually correlate with isotope highs. These data reflect the high degree of heterogeneity of such fracture

  17. Fish Distribution in Far Western Queensland, Australia: The Importance of Habitat, Connectivity and Natural Flows

    Directory of Open Access Journals (Sweden)

    Adam Kerezsy

    2014-06-01

    Full Text Available The endorheic Lake Eyre Basin drains 1.2 million square kilometres of arid central Australia, yet provides habitat for only 30 species of freshwater fish due to the scarcity of water and extreme climate. The majority are hardy riverine species that are adapted to the unpredictable flow regimes, and capable of massive population booms following heavy rainfall and the restoration of connectivity between isolated waterholes. The remainder are endemic specialists from isolated springs with very restricted ranges, and many are listed under relevant state and national endangered species legislation and also by the International Union for Conservation of Nature (IUCN. For these spring communities, which are sustained by water from the Great Artesian Basin, survival is contingent on suitable habitat persisting alongside extractive mining, agriculture and the imposition of alien species. For the riverine species, which frequently undertake long migrations into ephemeral systems, preservation of the natural flow regime is paramount, as this reinstates riverine connectivity. In this study, fish were sampled from the Bulloo River in the east to the Mulligan River in the west, along a temporal timeframe and using a standard set of sampling gears. Fish presence was influenced by factors such as natural catchment divides, sampling time, ephemerality and the occurrence of connection flows and flooding. Despite the comparatively low diversity of species, the aquatic systems of this isolated region remain in good ecological condition, and as such they offer excellent opportunities to investigate the ecology of arid water systems. However, the presence of both endangered species (in the springs and invasive and translocated species more widely indicates that active protection and management of this unique area is essential to maintain biodiversity and ecosystem integrity.

  18. Stress fractures of ankle and wrist in childhood: nature and frequency

    Energy Technology Data Exchange (ETDEWEB)

    Oestreich, Alan E. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States); Bhojwani, Nicholas [University of Cincinnati College of Medicine, Cincinnati, OH (United States)

    2010-08-15

    Stress fractures of many etiologies are found not infrequently in various tarsal bones but are less commonly recognized in carpal bones. To assess the distribution of tarsal and carpal stress fractures. During the last three decades, the senior author collected locations of tarsal and carpal bone stress fracture callus seen on plain radiographs. 527 children with tarsal and carpal stress fractures were identified (88 children had multiple bones involved). The totals were: calcaneus 244, cuboid 188, talus 121, navicular 24, cuneiforms 23, capitate 18, lunate 1, and scaphoid 1. Stress fractures were more frequently seen once we became aware each particular bone could be involved. Tarsal and carpal stress fractures in children are not rare. Careful perusal of these bones is urged in all susceptible children with limping or wrist pain. (orig.)

  19. A Novel Integrated Approach to Modelling of Depletion-Induced Change in Full Permeability Tensor of Naturally Fractured Reservoirs

    Directory of Open Access Journals (Sweden)

    Zahra Izadi

    2014-12-01

    Full Text Available More than half of all hydrocarbon reservoirs are Naturally Fractured Reservoirs (NFRs, in which production forecasting is a complicated function of fluid flow in a fracture-matrix system. Modelling of fluid flow in NFRs is challenging due to formation heterogeneity and anisotropy. Stress sensitivity and depletion effect on already-complex reservoir permeability add to the sophistication. Horizontal permeability anisotropy and stress sensitivity are often ignored or inaccurately taken into account when simulating fluid flow in NFRs. The aim of this paper is to present an integrated approach for evaluating the dynamic and true anisotropic nature of permeability in naturally fractured reservoirs. Among other features, this approach considers the effect of reservoir depletion on reservoir permeability tensor, allowing more realistic production forecasts. In this approach the NFR is discretized into grids for which an analytical model yields full permeability tensors. Then, fluid flow is modelled using the finite-element method to obtain pore-pressure distribution within the reservoir. Next, another analytical model evaluates the change in the aperture of individual fractures as a function of effective stress and rock mechanical properties. The permeability tensor of each grid is then updated based on the apertures obtained for the current time step. The integrated model proceeds according to the next prescribed time increments.

  20. New capillary number definition for displacement of residual nonwetting phase in natural fractures

    Science.gov (United States)

    AlQuaimi, B. I.; Rossen, W. R.

    2017-06-01

    We propose a new capillary number for flow in fractures starting with a force balance on a trapped ganglion in a fracture. The new definition is validated with laboratory experiments using five distinctive model fractures. Capillary desaturation curves were generated experimentally using water-air forced imbibition. The residual saturation-capillary number relationship obtained from different fractures, which vary in aperture and roughness, can be represented approximately by a single curve in terms of the new definition of the capillary number. They do not fit a single trend using the conventional definition of the capillary number.

  1. Connecting the Senses: Natural History and the British Museum in the Stereoscopic Magazine

    Directory of Open Access Journals (Sweden)

    Kathleen Davidson

    2014-10-01

    Full Text Available This article considers the connection between touch and sight by examining one of the early photographic ventures at the British Museum and efforts to mediate between popular and specialist access to the natural history collections. Part of the Victorians' fascination for natural history came from its appeal to the senses. Acknowledging the link between tactile and visual experiences as a component of intellectual discovery was an essential part of this, and the contemporary craze for stereoscopic photographs offered a chance to exploit this association. The article analyses the role of the tactile in the presentation of museum objects by addressing the 'impression' of touch - conjured optically and in the mind's eye - and compares the relative merits of the stereoscope to create the illusion of immersion for the viewer and to effectively convey the tactile qualities of the objects portrayed.

  2. Theory of Connectivity: Nature and Nurture of Cell Assemblies and Cognitive Computation

    Directory of Open Access Journals (Sweden)

    Meng eLi

    2016-04-01

    Full Text Available Richard Semon and Donald Hebb are among the firsts to put forth the notion of cell assembly – a group of coherently or sequentially-activated neurons– to represent percept, memory, or concept. Despite the rekindled interest in this age-old idea, the concept of cell assembly still remains ill-defined and its operational principle is poorly understood. What is the size of a cell assembly? How should a cell assembly be organized? What is the computational logic underlying Hebbian cell assemblies? How might Nature vs Nurture interact at the level of a cell assembly? In contrast to the widely assumed local randomness within the mature but naïve cell assembly, the recent Theory of Connectivity postulates that the brain consists of the developmentally pre-programmed cell assemblies known as the functional connectivity motif (FCM. Principal cells within such FCM is organized by the power-of-two-based mathematical principle that guides the construction of specific-to-general combinatorial connectivity patterns in neuronal circuits, giving rise to a full range of specific features, various relational patterns, and generalized knowledge. This pre-configured canonical computation is predicted to be evolutionarily conserved across many circuits, ranging from these encoding memory engrams and imagination to decision-making and motor control. Although the power-of-two-based wiring and computational logic places a mathematical boundary on an individual’s cognitive capacity, the fullest intellectual potential can be brought about by optimized nature and nurture. This theory may also open up a new avenue to examining how genetic mutations and various drugs might impair or enhance the computational logic of brain circuits.

  3. Theory of Connectivity: Nature and Nurture of Cell Assemblies and Cognitive Computation.

    Science.gov (United States)

    Li, Meng; Liu, Jun; Tsien, Joe Z

    2016-01-01

    Richard Semon and Donald Hebb are among the firsts to put forth the notion of cell assembly-a group of coherently or sequentially-activated neurons-to represent percept, memory, or concept. Despite the rekindled interest in this century-old idea, the concept of cell assembly still remains ill-defined and its operational principle is poorly understood. What is the size of a cell assembly? How should a cell assembly be organized? What is the computational logic underlying Hebbian cell assemblies? How might Nature vs. Nurture interact at the level of a cell assembly? In contrast to the widely assumed randomness within the mature but naïve cell assembly, the Theory of Connectivity postulates that the brain consists of the developmentally pre-programmed cell assemblies known as the functional connectivity motif (FCM). Principal cells within such FCM is organized by the power-of-two-based mathematical principle that guides the construction of specific-to-general combinatorial connectivity patterns in neuronal circuits, giving rise to a full range of specific features, various relational patterns, and generalized knowledge. This pre-configured canonical computation is predicted to be evolutionarily conserved across many circuits, ranging from these encoding memory engrams and imagination to decision-making and motor control. Although the power-of-two-based wiring and computational logic places a mathematical boundary on an individual's cognitive capacity, the fullest intellectual potential can be brought about by optimized nature and nurture. This theory may also open up a new avenue to examining how genetic mutations and various drugs might impair or improve the computational logic of brain circuits.

  4. WATER BREAKTHROUGH SIMULATION IN NATURALLY FRACTURED GAS RESERVOIRS WITH WATER DRIVE

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lie-hui; FENG Guo-qing; LI xiao-ping; LI Yun

    2005-01-01

    In the fractured water drive reservoirs of China, because of the complex geological conditions, almost all the active water invasions appear to be water breakthrough along fractures, especially along macrofractures. These seal the path of gas flow, thus the remaining gas in the pores mixes into water, and leads to gas-water interactive distribution in the fractured gas reservoir. These complicated fractured systems usually generate some abnormal flowing phenomena such as the crestal well produces water while the downdip well in the same gas reservoir produces gas, or the same gas well produces water intermittently. It is very difficult to explain these phenomena using existing fracture models because of their simple handling macrofractures without considering nonlinear flowing in the macrofractures and the low permeability matrix. Therefore, a nonlinear combined-flowing multimedia simulation model was successfully developed in this paper by introducing the equations of macrofractures and considering nonlinear flow in the macrofractures and the matrix. This model was then applied to actual fractured bottom water gas fields. Sensitivity studies of gas production by water drainage in fractured gas reservoirs were completed and the effect of different water drainage intensity and ways on actual gas production using this model were calculated. This model has been extensively used to predict the production performance in various fractured gas fields and proven to be reliable.

  5. NATURE FACILITATES CONNECTION WITH THE PROFOUND SELF: NEEDS, GOALS AND RESOURCE AWARENESS

    Directory of Open Access Journals (Sweden)

    Nicoleta Răban-Motounu

    2014-11-01

    Full Text Available The present study is based on Kaplan and Kaplan’s (1989 theory explaining the restorative effects that nature has on a person’s psychic. According to this theory, nature exerts a “soft fascination” combining the activation of involuntary attention mechanisms with the reflexive awareness, allowing a spontaneous detachment from stress factors and automatic functioning, and also the feeling of compatibility between personal purposes, and the possibilities for action offered by the environment (a sense of meaning. Our objective was to investigate the effects of nature on Self awareness: the immediate, emotional experience; needs awareness and organization; plans for action, and availability of resources, both personal, and external. We conducted an experiment with an experimental group (persons watching a video with life in nature and an active control group (involved in a psychotherapeutic technique focused on confronting and solving personal difficulties by creative means, accompanied by a short psychological analysis. The effects were assessed in terms of “here and now” emotions and available resources according to a self-evaluation scale, and with open-ended questions regarding personal needs and goals. The results showed that, for the experimental group, the relaxation effects and the awareness of long term goals were stronger, while all the other effects were the same as for the control group. The results suggest that indeed, nature helps a person get in contact with her profound Self, allowing the access to both “here and now” basic needs, and also long term goals (inner sources of meaning, the sense of connection between internal tendencies, personal, and external resources, resulting in increased positive emotions, and decreased negative emotions. Nature contemplation may facilitate a meditative state whit all its positive effects.

  6. A Simple Analytical Approach to Simulate Underbalanced- drilling in Naturally Fractured Reservoirs—The Effect of Short Overbalanced Conditions and Time Effect

    Directory of Open Access Journals (Sweden)

    Knut Inge Andersen

    2010-09-01

    Full Text Available This paper describes an analytical approach to investigate the nature of short overbalanced conditions and time effects during underbalanced drilling (UBD in a naturally fractured reservoir. This study uses an analytical model which is developed for kinetic invasion of mud into the fractures. The model is based on fluid flow between two parallel plates, which is further extended to model the fluid flow in a fractured formation. The effect of short overbalanced pressure and the time effect during UBD as well as the aspects of well productivity and flow efficiency are explained. This model is an Excel-based program and provides a fast and convenient tool for analysis and evaluation of drilling conditions (mud properties, time, and pressure of drilling in a fractured formation. The model can also predict the impact of the fracture and mud properties on the depth of invasion in the fractured formations.

  7. Likeability of Garden Birds: Importance of Species Knowledge & Richness in Connecting People to Nature.

    Science.gov (United States)

    Cox, Daniel T C; Gaston, Kevin J

    2015-01-01

    Interacting with nature is widely recognised as providing many health and well-being benefits. As people live increasingly urbanised lifestyles, the provision of food for garden birds may create a vital link for connecting people to nature and enabling them to access these benefits. However, it is not clear which factors determine the pleasure that people receive from watching birds at their feeders. These may be dependent on the species that are present, the abundance of individuals and the species richness of birds around the feeders. We quantitatively surveyed urban households from towns in southern England to determine the factors that influence the likeability of 14 common garden bird species, and to assess whether people prefer to see a greater abundance of individuals or increased species richness at their feeders. There was substantial variation in likeability across species, with songbirds being preferred over non-songbirds. Species likeability increased for people who fed birds regularly and who could name the species. We found a strong correlation between the number of species that a person could correctly identify and how connected to nature they felt when they watched garden birds. Species richness was preferred over a greater number of individuals of the same species. Although we do not show causation this study suggests that it is possible to increase the well-being benefits that people gain from watching birds at their feeders. This could be done first through a human to bird approach by encouraging regular interactions between people and their garden birds, such as through learning the species names and providing food. Second, it could be achieved through a bird to human approach by increasing garden songbird diversity because the pleasure that a person receives from watching an individual bird at a feeder is dependent not only on its species but also on the diversity of birds at the feeder.

  8. Failure Analysis on Fracture of Worm-gear Connecting Bolts%蜗轮连接螺栓断裂失效分析

    Institute of Scientific and Technical Information of China (English)

    王荣; 李玲

    2012-01-01

    装卸料机上的蜗轮连接螺栓材料为35钢,强度等级为10.9级,在设备运行大约10a后发生断裂。对断裂螺栓进行宏观、化学成分、硬度、金相、能谱和断口分析后得出,该螺栓的断裂性质为双向弯曲疲劳断裂,螺栓表面的脱碳和螺纹颈部的应力集中降低了该部位的疲劳性能。通过综合分析和螺栓受力估算后得出,螺栓断裂的主要原因是螺栓和内齿轮螺栓孔之间存在较大的间隙,使螺栓的受力状态和受力大小过早地发生了变化,造成连接螺栓疲劳断裂。%The worm-gear connecting bolts of refueling machines of a nuclear power plant,with material of 35 steel and strength grade of 10.9,fractured after the device running for about a decade,and means such as macro examination,chemical compositions analysis,hardness test,metallographic examination,fracture SEM analysis and so on,were used to analyze the fractured bolts.The results show that the fracture property of the bolts is two-way bending fatigue fracture.Surface decarburization of the bolts and stress concentration at the bolt thread neck decreased the fatigue strength,which resulted fatigue cracks formed here.By comprehensive analysis and force estimating,it was concluded that the main reason for the fracture is that there is a big gap between the bolt shank parts and their matching internal gear bolt holes,which made the force state and force size of the bolts changed early and finally resulted in fatigue fracture of the worm-gear connecting bolts.

  9. On the Nature of the Intrinsic Connectivity of the Cat Motor Cortex: Evidence for a Recurrent Neural Network Topology

    DEFF Research Database (Denmark)

    Capaday, Charles; Ethier, C; Brizzi, L

    2009-01-01

    Capaday C, Ethier C, Brizzi L, Sik A, van Vreeswijk C, Gingras D. On the nature of the intrinsic connectivity of the cat motor cortex: evidence for a recurrent neural network topology. J Neurophysiol 102: 2131-2141, 2009. First published July 22, 2009; doi: 10.1152/jn.91319.2008. The details...... and functional significance of the intrinsic horizontal connections between neurons in the motor cortex (MCx) remain to be clarified. To further elucidate the nature of this intracortical connectivity pattern, experiments were done on the MCx of three cats. The anterograde tracer biocytin was ejected...

  10. Geochemical Trends and Natural Attenuation of RDX, Nitrate, and Perchlorate in the Hazardous Test Area Fractured-Granite Aquifer, White Sands Missile Range, New Mexico, 1996-2006

    Science.gov (United States)

    Langman, Jeff B.; Robertson, Andrew J.; Bynum, Jamar; Gebhardt, Fredrick E.

    2008-01-01

    A fractured-granite aquifer at White Sands Missile Range is contaminated with the explosive compound RDX, nitrate, and perchlorate (oxidizer associated with rocket propellant) from the previous use of the Open Burn/Open Detonation site at the Hazardous Test Area. RDX, nitrate, and perchlorate ground-water concentrations were analyzed to examine source characteristics, spatial and temporal variability, and the influence of the natural attenuation processes of dilution and degradation in the Hazardous Test Area fractured-granite aquifer. Two transects of ground-water wells from the existing monitoring-site network - one perpendicular to ground-water flow (transect A-A') and another parallel to ground-water flow (transect B-B') - were selected to examine source characteristics and the spatial and temporal variability of the contaminant concentrations. Ground-water samples collected in 2005 from a larger sampling of monitoring sites than the two transects were analyzed for various tracers including major ions, trace elements, RDX degradates, dissolved gases, water isotopes, nitrate isotopes, and sulfate isotopes to examine the natural attenuation processes of dilution and degradation. Recharge entrains contaminants at the site and transports them downgradient towards the Tularosa Basin floor through a poorly connected fracture system(s). From 1996 to 2006, RDX, nitrate, and perchlorate concentrations in ground water downgradient from the Open Burn/Open Detonation site have been relatively stable. RDX, nitrate, and perchlorate in ground water from wells near the site indicate dispersed contaminant sources in and near the Open Burn/Open Detonation pits. The sources of RDX and nitrate in the pit area have shifted with time, and the shift correlates with the regrading of the south and east berms of each pit in 2002 and 2003 following closure of the site. The largest RDX concentrations were in ground water about 0.1 mile downgradient from the pits, the largest perchlorate

  11. The right hemisphere is highlighted in connected natural speech production and perception.

    Science.gov (United States)

    Alexandrou, Anna Maria; Saarinen, Timo; Mäkelä, Sasu; Kujala, Jan; Salmelin, Riitta

    2017-05-15

    Current understanding of the cortical mechanisms of speech perception and production stems mostly from studies that focus on single words or sentences. However, it has been suggested that processing of real-life connected speech may rely on additional cortical mechanisms. In the present study, we examined the neural substrates of natural speech production and perception with magnetoencephalography by modulating three central features related to speech: amount of linguistic content, speaking rate and social relevance. The amount of linguistic content was modulated by contrasting natural speech production and perception to speech-like non-linguistic tasks. Meaningful speech was produced and perceived at three speaking rates: normal, slow and fast. Social relevance was probed by having participants attend to speech produced by themselves and an unknown person. These speech-related features were each associated with distinct spatiospectral modulation patterns that involved cortical regions in both hemispheres. Natural speech processing markedly engaged the right hemisphere in addition to the left. In particular, the right temporo-parietal junction, previously linked to attentional processes and social cognition, was highlighted in the task modulations. The present findings suggest that its functional role extends to active generation and perception of meaningful, socially relevant speech. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  12. Advanced Reservoir Characterization and Evaluation of C02 Gravity Drainage in the Naturally Fractured Sprayberry Trend Area

    Energy Technology Data Exchange (ETDEWEB)

    David S. Schechter

    1998-04-30

    The objective is to assess the economic feasibility of CO2 flooding of the naturally fractured Straberry Trend Area in west Texas. Research is being conducted in the extensive characterization of the reservoirs, the experimental studies of crude oil/brine/rock (COBR) interaction in the reservoirs, the analytical and numerical simulation of Spraberry reservoirs, and the experimental investigations on CO2 gravity drainage in Spraberry whole cores.

  13. Speech Enhancement with Natural Sounding Residual Noise Based on Connected Time-Frequency Speech Presence Regions

    Directory of Open Access Journals (Sweden)

    Sørensen Karsten Vandborg

    2005-01-01

    Full Text Available We propose time-frequency domain methods for noise estimation and speech enhancement. A speech presence detection method is used to find connected time-frequency regions of speech presence. These regions are used by a noise estimation method and both the speech presence decisions and the noise estimate are used in the speech enhancement method. Different attenuation rules are applied to regions with and without speech presence to achieve enhanced speech with natural sounding attenuated background noise. The proposed speech enhancement method has a computational complexity, which makes it feasible for application in hearing aids. An informal listening test shows that the proposed speech enhancement method has significantly higher mean opinion scores than minimum mean-square error log-spectral amplitude (MMSE-LSA and decision-directed MMSE-LSA.

  14. Analysis of the migration characteristics of tracers in a heterogeneous flow field through a natural fracture of a domestic granite

    Energy Technology Data Exchange (ETDEWEB)

    Kum, Y. S.; Park, J. K.; Han, P. S. [KAERI, Taejon (Korea, Republic of)

    2001-05-01

    Tracers migration experiment was performed in a natural fracture of a domestic granite. The scale of rock fracture was 100x60x40(cm). In order to observe the migration characteristics, two kinds of nonsorbing tracers were used; as high molecular organic dyes, Eosine, and NaLS, and as anions, Bromide and Chloride. Tracers was injected in a borehole as a band funtion and collected at the opposite borehole. A variable aperture channel model with particle tracking method was used to characterize the aperture width of the fracture and to simulate solute transport. The heterogeneous flow field was modeled by a variable aperture channel model after characterizing aperture distribution by hydraulic tests through boreholes. The particle tracking method applied effectively in simulating tracers transport through a heterogeneous flow field in the rock fracture. Simulated results show that tracers do not migrate through the shortest straight line between inlet and outlet, but migrate through the paths having lowest flow resistance. that is channeling flow.

  15. Permeability reduction by pyrobitumen, mineralization, and stress along large natural fractures in sandstones at 18,300 ft. depth: Destruction of a reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, J.C. [SPE, Richardson, TX (United States)]|[Sandia National Lab., Albuquerque, NM (United States); Billingsley, R.L.; Evans, L.W.

    1996-11-01

    Production of gas from the Frontier Formation at 18,300 R depth in the Frewen No. 4 Deep well, eastern Green River basin (Wyoming), was uneconomic despite the presence of numerous open natural fractures. Initial production tested at 500 MCFD, but dropped from 360 MCFD to 140 MCFD during a 10-day production test, and the well was abandoned. Examination of the fractures in the core suggests several probable reasons for this poor production. One factor is the presence of a hydrocarbon residue (carbon) which filled much of the porosity left in the smaller fractures after mineralization. An equally important factor is probably the reorientation of the in situ horizontal compressive stress to a trend normal to the main fractures, and which now acts to close fracture apertures rapidly during reservoir drawdown. This data set has unpleasant implications for the search for similar, deep fractured reservoirs.

  16. Metatarsal stress fractures - aftercare

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000553.htm Metatarsal stress fractures - aftercare To use the sharing features on ... that connect your ankle to your toes. A stress fracture is a break in the bone that ...

  17. An example of using oil-production induced microseismicity in characterizing a naturally fractured reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Rutledge, J.T.; Phillips, W.S. [Nambe Geophysical, Inc., Santa Fe, NM (United States); Schuessler, B.K.; Anderson, D.W. [Los Alamos National Lab., NM (United States)

    1996-06-01

    Microseismic monitoring was conducted using downhole geophone tools deployed in the Seventy-Six oil field, Clinton County, Kentucky. Over a 7-month monitoring period, 3237 microearthquakes were detected during primary oil production; no injection operations were conducted. Gross changes in production rate correlate with microearthquake event rate with event rate lagging production-rate changes by about 2 weeks. Hypocenters and first-motion data have revealed low-angle, thrust fracture zones above and below the currently drained depth interval. Production history, well logs and drill tests indicate the seismically-active fractures are previously drained intervals that have subsequently recovered to hydrostatic pressure via brine invasion. The microseismic data have revealed, for the first time, the importance of the low-angle fractures in the storage and production of oil in the study area. The seismic behavior is consistent with poroelastic models that predict slight increases in compressive stress above and below currently drained volumes.

  18. 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

  19. Quantifying porosity and permeability of fractured carbonates and fault rocks in natural groundwater reservoirs

    Science.gov (United States)

    Pirmoradi, Reza; Wolfmayr, Mariella; Bauer, Helene; Decker, Kurt

    2017-04-01

    This study presents porosity and permeability data for a suite of different carbonate rocks from two major groundwater reservoirs in eastern Austria that supply more than 60% of Vienna`s drinking water. Data includes a set of lithologically different, unfractured host rocks, fractured rocks with variable fracture intensities, and fault rocks such as dilation breccias, different cataclasites and dissolution-precipitation fault rocks. Fault rock properties are of particular importance, since fault zones play an important role in the hydrogeology of the reservoirs. The reservoir rocks are exposed at two major alpine karst plateaus in the Northern Calcareous Alps. They comprise of various Triassic calcareous strata of more than 2 km total thickness that reflect facies differentiation since Anisian times. Rocks are multiply deformed resulting in a partly dense network of fractures and faults. Faults differ in scale, fault rock content, and fault rock volumes. Methods used to quantify the porosity and permeability of samples include a standard industry procedure that uses the weight of water saturated samples under hydrostatic uplift and in air to determine the total effective (matrix and fracture) porosity of rocks, measurements on plugs with a fully automated gas porosity- and permeameter using N2 gas infiltrating plugs under a defined confining pressure (Coreval Poro 700 by Vinci technologies), and percolation tests. The latter were conducted in the field along well known fault zones in order to test the differences in fractured rock permeability in situ and on a representative volume, which is not ensured with plug measurements. To calculate hydraulic conductivity by the Darcy equation the measured elapsed time for infiltrating a standard volume of water into a small borehole has been used. In general, undisturbed host rock samples are all of low porosity (average around 1%). The open porosity of the undisturbed rocks belonging to diverse formations vary from 0

  20. Connecting the Public to Natural Hazards Through a Hands-on Museum Exhibit

    Science.gov (United States)

    Olds, S. E.; Rowe, S. M.; Hanshumaker, W.; Farley, M.

    2014-12-01

    Communities along the coast of Oregon, Washington, and northern California live with the threat of potentially devastating subduction zone earthquakes and subsequent tsunami that could happen at any time. Both residents and visitors to the coast need to be aware of the potential impacts such hazards can have on their lives as well as what to do during an earthquake and before a tsunami hits. To raise awareness of both natural hazards and the technologies used to monitor them, UNAVCO designed and installed a museum exhibit on display at Oregon State University's Hatfield Marine Science Center (HMSC) Visitor Center in Newport, Oregon. The objectives for the exhibit are to increase familiarization with the natural hazards of earthquakes and tsunamis in the Cascadia region, to explain the connection between the crust's movement and compression over time with the potential strength of a subduction-zone earthquake, and to inform visitors about high-precision, high-rate GPS technology. The exhibit includes multiple hands-on models and an authentic GPS monitoring station. Additionally, panels explain the science behind the models, potential impacts of a great earthquake to society, and actions visitors can take to practice earthquake safety through the Great ShakeOut earthquake drill. Over the past year that the exhibit has been open to the public, it has been visited by over 100,000 people including students, family and senior groups, and the general public. Anecdotal evidence indicates that two components of the exhibit create the most visitor impact providing visitors with 'ah ha moments': a real-scale tape measure showing the approximate 12 foot distance the coast has compressed over the past 300+ years, and a flexible map illustrating that the coastal areas are compressing the most compared to areas further inland. Through HMSC's NSF-funded Cyberlab automated visitor data collection system, we have been able to document and analyze a variety of visitor characteristics

  1. A Natural-Rule-Based-Connection (NRBC Method for River Network Extraction from High-Resolution Imagery

    Directory of Open Access Journals (Sweden)

    Chuiqing Zeng

    2015-10-01

    Full Text Available This study proposed a natural-rule-based-connection (NRBC method to connect river segments after water body detection from remotely sensed imagery. A complete river network is important for many hydrological applications. While water body detection methods using remote sensing are well-developed, less attention has been paid to connect discontinuous river segments and form a complete river network. This study designed an automated NRBC method to extract a complete river network by connecting river segments at polygon level. With the assistance of an image pyramid, neighbouring river segments are connected based on four criteria: gap width (Tg, river direction consistency (Tθ, river width consistency (Tw, and minimum river segment length (Tl. The sensitivity of these four criteria were tested, analyzed, and proper criteria values were suggested using image scenes from two diverse river cases. The comparison of NRBC and the alternative morphological method demonstrated NRBC’s advantage of natural rule based selective connection. We refined a river centerline extraction method and show how it outperformed three other existing centerline extraction methods on the test sites. The extracted river polygons and centerlines have a multitude of end uses including rapidly mapping flood extents, monitoring surface water supply, and the provision of validation data for simulation models required for water quantity, quality and aquatic biota assessments. The code for the NRBC is available on GitHub.

  2. Advanced Reservoir Characterization and Evaluation of CO{sub 2} Gravity Drainage in the Naturally Fractured Spraberry Trend Area

    Energy Technology Data Exchange (ETDEWEB)

    Schechter, D.S.

    1999-02-03

    The overall goal of this project is to assess the economic feasibility of CO{sub 2} flooding the naturally fractured Spraberry Trend Area in West Texas. This objective is being accomplished by conducting research in four areas: (1) extensive characterization of the reservoirs, (2) experimental studies of crude oil/brine/rock (COBR) interactions in the reservoirs, (3) reservoir performance analysis, and, (4) experimental investigations on CO2 gravity drainage in Spraberry whole cores. This report provides results of the third year of the five-year project for each of the four areas including a status report of field activities leading up to injection of CO2.

  3. Advanced Reservoir Characterization and Evaluation of CO2 Gravity Drainage in the Naturally Fractured Spraberry Trend Area, Class III

    Energy Technology Data Exchange (ETDEWEB)

    Knight, Bill; Schechter, David S.

    2002-07-26

    The goal of this project was to assess the economic feasibility of CO2 flooding the naturally fractured Spraberry Trend Area in west Texas. This objective was accomplished through research in four areas: (1) extensive characterization of the reservoirs, (2) experimental studies of crude oil/brine/rock (COBR) interactions in the reservoirs, (3) reservoir performance analysis, and (4) experimental investigations on CO2 gravity drainage in Spraberry whole cores. This provides results of the final year of the six-year project for each of the four areas.

  4. Infiltration and hydraulic connections from the Niagara River to a fractured-dolomite aquifer in Niagara Falls, New York

    Science.gov (United States)

    Yager, Richard M.; Kappel, William M.

    1998-04-01

    The spatial distribution of hydrogen and oxygen stable-isotope values in groundwater can be used to distinguish different sources of recharge and to trace groundwater flow directions from recharge boundaries. This method can be particularly useful in fractured-rock settings where multiple lines of evidence are required to delineate preferential flow paths that result from heterogeneity within fracture zones. Flow paths delineated with stable isotopes can be combined with hydraulic data to form a more complete picture of the groundwater flow system. In this study values of δD and δ 18O were used to delineate paths of river-water infiltration into the Lockport Group, a fractured dolomite aquifer, and to compute the percentage of river water in groundwater samples from shallow bedrock wells. Flow paths were correlated with areas of high hydraulic diffusivity in the shallow bedrock that were delineated from water-level fluctuations induced by diurnal stage fluctuations in man-made hydraulic structures. Flow paths delineated with the stable-isotope and hydraulic data suggest that river infiltration reaches an unlined storm sewer in the bedrock through a drainage system that surrounds carrying river water to hydroelectric power plants. This findings is significant because the storm sewer is the discharge point for contaminated groundwater from several chemical waste-disposal sites and the cost of treating the storm sewer's discharge could be reduced if the volume of infiltration from the river were decreased.

  5. AIED 2009 Workshops Proceeedings Volume 10: Natural Language Processing in Support of Learning: Metrics, Feedback and Connectivity

    NARCIS (Netherlands)

    Dessus, Philippe; Trausan-Matu, Stefan; Van Rosmalen, Peter; Wild, Fridolin

    2009-01-01

    Dessus, P., Trausan-Matu, S., Van Rosmalen, P., & Wild, F. (Eds.) (2009). AIED 2009 Workshops Proceedings Volume 10 Natural Language Processing in Support of Learning: Metrics, Feedback and Connectivity. In S. D. Craig & D. Dicheva (Eds.), AIED 2009: 14th International Conference in Artificial

  6. Detection and Characterization of Natural and Induced Fractures for the Development of Enhanced Geothermal Systems

    Energy Technology Data Exchange (ETDEWEB)

    Toksoz, M. Nafi [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Dept. of Earth, Atmospheric and Planetary Sciences

    2013-04-06

    The objective of this 3-year project is to use various geophysical methods for reservoir and fracture characterization. The targeted field is the Cove Fort-Sulphurdale Geothermal Field in Utah operated by ENEL North America (ENA). Our effort has been focused on 1) understanding the regional and local geological settings around the geothermal field; 2) collecting and assembling various geophysical data sets including heat flow, gravity, magnetotelluric (MT) and seismic surface and body wave data; 3) installing the local temporary seismic network around the geothermal site; 4) imaging the regional and local seismic velocity structure around the geothermal field using seismic travel time tomography; and (5) determining the fracture direction using the shear-wave splitting analysis and focal mechanism analysis. Various geophysical data sets indicate that beneath the Cove Fort-Sulphurdale Geothermal Field, there is a strong anomaly of low seismic velocity, low gravity, high heat flow and high electrical conductivity. These suggest that there is a heat source in the crust beneath the geothermal field. The high-temperature body is on average 150 °C – 200 °C hotter than the surrounding rock. The local seismic velocity and attenuation tomography gives a detailed velocity and attenuation model around the geothermal site, which shows that the major geothermal development target is a high velocity body near surface, composed mainly of monzonite. The major fracture direction points to NNE. The detailed velocity model along with the fracture direction will be helpful for guiding the geothermal development in the Cove Fort area.

  7. River-spring connectivity and hydrogeochemical interactions in a shallow fractured rock formation. The case study of Fuensanta river valley (Southern Spain)

    Science.gov (United States)

    Barberá, J. A.; Andreo, B.

    2017-04-01

    In upland catchments, the hydrology and hydrochemistry of streams are largely influenced by groundwater inflows, at both regional and local scale. However, reverse conditions (groundwater dynamics conditioned by surface water interferences), although less described, may also occur. In this research, the local river-spring connectivity and induced hydrogeochemical interactions in intensely folded, fractured and layered Cretaceous marls and marly-limestones (Fuensanta river valley, S Spain) are discussed based on field observations, tracer tests and hydrodynamic and hydrochemical data. The differential flow measurements and tracing experiments performed in the Fuensanta river permitted us to quantify the surface water losses and to verify its direct hydraulic connection with the Fuensanta spring. The numerical simulations of tracer breakthrough curves suggest the existence of a groundwater flow system through well-connected master and tributary fractures, with fast and multi-source flow components. Furthermore, the multivariate statistical analysis conducted using chemical data from the sampled waters, the geochemical study of water-rock interactions and the proposed water mixing approach allowed the spatial characterization of the chemistry of the springs and river/stream waters draining low permeable Cretaceous formations. Results corroborated that the mixing of surface waters, as well as calcite dissolution and CO2 dissolution/exsolution, are the main geochemical processes constraining Fuensanta spring hydrochemistry. The estimated contribution of the tributary surface waters to the spring flow during the research period was approximately 26-53% (Fuensanta river) and 47-74% (Convento stream), being predominant the first component during high flow and the second one during the dry season. The identification of secondary geochemical processes (dolomite and gypsum dissolution and dedolomitization) in Fuensanta spring waters evidences the induced hydrogeochemical

  8. A Thermoelastic Hydraulic Fracture Design Tool for Geothermal Reservoir Development

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad Ghassemi

    2003-06-30

    Geothermal energy is recovered by circulating water through heat exchange areas within a hot rock mass. Geothermal reservoir rock masses generally consist of igneous and metamorphic rocks that have low matrix permeability. Therefore, cracks and fractures play a significant role in extraction of geothermal energy by providing the major pathways for fluid flow and heat exchange. Thus, knowledge of conditions leading to formation of fractures and fracture networks is of paramount importance. Furthermore, in the absence of natural fractures or adequate connectivity, artificial fracture are created in the reservoir using hydraulic fracturing. At times, the practice aims to create a number of parallel fractures connecting a pair of wells. Multiple fractures are preferred because of the large size necessary when using only a single fracture. Although the basic idea is rather simple, hydraulic fracturing is a complex process involving interactions of high pressure fluid injections with a stressed hot rock mass, mechanical interaction of induced fractures with existing natural fractures, and the spatial and temporal variations of in-situ stress. As a result it is necessary to develop tools that can be used to study these interactions as an integral part of a comprehensive approach to geothermal reservoir development, particularly enhanced geothermal systems. In response to this need we have set out to develop advanced thermo-mechanical models for design of artificial fractures and rock fracture research in geothermal reservoirs. These models consider the significant hydraulic and thermo-mechanical processes and their interaction with the in-situ stress state. Wellbore failure and fracture initiation is studied using a model that fully couples poro-mechanical and thermo-mechanical effects. The fracture propagation model is based on a complex variable and regular displacement discontinuity formulations. In the complex variable approach the displacement discontinuities are

  9. Paleostress Reconstruction from 3D seismic, Natural Fracture and Calcite Twin Analyses: Structural Insights into the Otway Basin, Australia

    Science.gov (United States)

    Burgin, Hugo; Amrouch, Khalid; Holford, Simon

    2017-04-01

    The Otway Basin, Australia, is of particular interest due to its significance as an Australian hydrocarbon producing province and a major global CO2 burial project. Structural data was collected in the form of natural fractures from wellbore image logs and outcrop in addition to calcite twin analyses, within formations from the mid cretaceous from both on and offshore. Evidence for four structural events within the study area have been identified including NE-SW and NW-SE orientated extension, in addition to a NW-SE compressive event. Natural fracture data also reveals a previously "un-detected" NE-SW compression within the Otway Basin. This study presents the first investigation of paleostress environments within the region from micro, meso and macro scale tectonic data in both onshore and offshore in addition to the first quantification of differential paleostresses. This work highlights the importance of a comprehensive understanding of four dimensional stress evolution within the sedimentary basins of Australia's southern margin.

  10. Paucity of horizontal connections for binocular vision in V1 of naturally strabismic macaques: Cytochrome oxidase compartment specificity.

    Science.gov (United States)

    Tychsen, Lawrence; Wong, Agnes Ming-Fong; Burkhalter, Andreas

    2004-06-21

    To describe the structural basis for lack of binocular fusion in strabismic primates, we investigated intrinsic horizontal connections within striate cortex (area V1) of normal and strabismic, adult macaque monkeys. The strabismic animals had early-onset natural esotropia (the visual axes deviated nasally), normal visual acuity in each eye, and the constellation of ocular motor deficits that typify human infantile strabismus. Horizontal patchy connections and synaptic boutons were labeled by injections of the neuronal tracer biotinylated dextran amine. Ocular dominance columns (ODCs), and blob vs. interblob compartments, were revealed by using cytochrome oxidase (CO). In layers 2/3 and 4B of the strabismic monkeys, patchy projections and boutons terminated much more frequently in same-eye (73%) as opposed to opposite-eye (27%) ODCs (normal monkeys 58% and 42%, respectively). The deficiency of binocular connections in the strabismic cortex was evident qualitatively as a "skip" pattern, in which every other row of ODCs had labeled patches. Analysis of V1 in normal monkeys revealed that the deficits in strabismic V1 were due mainly to a loss of binocular connections between neurons in CO-interblob compartments. In both normal and strabismic monkeys: (1) CO-blob compartment neurons showed a more pronounced bias for monocular connectivity, and (2) commitment of connections to the same CO-compartment as the injection site (blob-to-blob, or interblob-to-interblob) was moderately strong (64%) but far from absolute. These findings help elucidate the relative roles of visual experience vs. innate mechanisms in the development of axonal connections between ocular dominance domains and compartments within macaque V1. They also provide the first detailed description of the V1 maldevelopments associated with unrepaired natural, infantile-onset strabismus in primates.

  11. Hydrologic connectivity to streams increases nitrogen and phosphorus inputs and cycling in soils of created and natural floodplain wetlands.

    Science.gov (United States)

    Wolf, Kristin L; Noe, Gregory B; Ahn, Changwoo

    2013-07-01

    Greater connectivity to stream surface water may result in greater inputs of allochthonous nutrients that could stimulate internal nitrogen (N) and phosphorus (P) cycling in natural, restored, and created riparian wetlands. This study investigated the effects of hydrologic connectivity to stream water on soil nutrient fluxes in plots ( = 20) located among four created and two natural freshwater wetlands of varying hydrology in the Piedmont physiographic province of Virginia. Surface water was slightly deeper; hydrologic inputs of sediment, sediment-N, and ammonium were greater; and soil net ammonification, N mineralization, and N turnover were greater in plots with stream water classified as their primary water source compared with plots with precipitation or groundwater as their primary water source. Soil water-filled pore space, inputs of nitrate, and soil net nitrification, P mineralization, and denitrification enzyme activity (DEA) were similar among plots. Soil ammonification, N mineralization, and N turnover rates increased with the loading rate of ammonium to the soil surface. Phosphorus mineralization and ammonification also increased with sedimentation and sediment-N loading rate. Nitrification flux and DEA were positively associated in these wetlands. In conclusion, hydrologic connectivity to stream water increased allochthonous inputs that stimulated soil N and P cycling and that likely led to greater retention of sediment and nutrients in created and natural wetlands. Our findings suggest that wetland creation and restoration projects should be designed to allow connectivity with stream water if the goal is to optimize the function of water quality improvement in a watershed.

  12. Experimental Study of Formation Damage during Underbalanced-Drilling in Naturally Fractured Formations

    Directory of Open Access Journals (Sweden)

    Siroos Salimi

    2011-10-01

    Full Text Available This paper describes an experimental investigation of formation damage in a fractured carbonate core sample under underbalanced drilling (UBD conditions. A major portion of this study has concentrated on problems which are often associated with UBD and the development of a detailed protocol for proper design and execution of an UBD program. Formation damage effects, which may occur even if the underbalanced pressure condition is maintained 100% of the time during drilling operation, have been studied. One major concern for formation damage during UBD operations is the loss of the under-balanced pressure condition. Hence, it becomes vital to evaluate the sensitivity of the formation to the effect of an overbalanced pulse situation. The paper investigates the effect of short pulse overbalance pressure during underbalanced conditions in a fractured chalk core sample. Special core tests using a specially designed core holder are conducted on the subject reservoir core. Both overbalance and underbalanced tests were conducted with four UBD drilling fluids. Core testing includes measurements of the initial permeability and return permeability under two different pressure conditions (underbalanced and overbalanced. Then the procedure is followed by applying a differential pressure on the core samples to mimic the drawdown effect to determine the return permeability capacity. In both UBD and short pulse OBP four mud formulations are used which are: lab oil, brine (3% KCL, water-based mud (bentonite with XC polymer and fresh water. The return permeability measurements show that a lab oil system performed fairly well during UBD and short OB conditions. The results indicate that a short overbalance pressure provides a significant reduction in permeability of the fractured formations. In most tests, even application of a high drawdown pressure during production cannot restore the initial permeability by more than 40%.

  13. Fluid-driven fractures in brittle hydrogels

    Science.gov (United States)

    O'Keeffe, Niall; Linden, Paul

    2016-11-01

    Hydraulic fracturing is a process in which fluid is injected deep underground at high pressures that can overcome the strength of the surrounding matrix. This results in an increase of surface area connected to the well bore and thus allows extraction of natural gas previously trapped in a rock formation. We experimentally study the physical mechanisms of these fluid-driven fractures in low permeability reservoirs where the leak-off of fracturing fluid is considered negligible. This is done through the use of small scale experiments on transparent and brittle, heavily cross-linked hydrogels. The propagation of these fractures can be split into two distinct regimes depending on whether the dominant energy dissipation mechanism is viscous flow or material toughness. We will analyse crack growth rates, crack thickness and tip shape in both regimes. Moreover, PIV techniques allow us to explore the flow dynamics within the fracture, which is crucial in predicting transport of proppants designed to prevent localisation of cracks.

  14. The influence of phase transformation hardening on continuous laser processing of notches for fracture splitting of a C70S6 connecting rod

    Science.gov (United States)

    Kou, S. Q.; Gao, Y.; Shi, Z.

    2017-01-01

    The dynamic process of local material microstructure and hardness of continuous laser grooving for fracture splitting of a C70S6 connecting rod was studied. According to the phase transformation characteristics of C70S6 steel during laser processing, the coupling calculation between the transient temperature field and phase transformation process of continuous laser grooving was carried out, and then the phase transformation process and phase compositions in the heat affected zone (HAZ) was obtained. The research results showed that the HAZ was composed of martensite and pearlite as well as residual austenite after continuous laser grooving, and the generation of the martensite in the HAZ is beneficial to the subsequent splitting process; meanwhile, the hardening effect of continuous laser grooving is remarkable on the HAZ, and the requirement for the cutting tool and technique used at the subsequent machining process for the fine boring of the big end hole should be higher.

  15. A new system for understanding the biodiversity in different nature reserves:capacity,connectivity and quality of biodiversity

    Institute of Scientific and Technical Information of China (English)

    Zhenji LI; Jiakuan CHEN; Yunqiu RUAN; Ying CHANG; Wen WE; Luzhen CHEN; Dongliang ZHOU

    2009-01-01

    In this paper,we propose a new system for understanding the biodiversity in different conservation areas.It includes three aspects:the capacity,the connectivity and the quality.The capacity refers to the numbers of biodiversity,including absolute and relative richness of the vegetation types Nv and Dv = (Nv-1)/lnA,species numbers S and richness of species dGI = (S- 1)/lnA,and germ plasm resources within a nature reserve,and also the potential biological living space offered by the natural resource.It comprises the total biological resources in a nature reserve.The connectivity refers to the flux of biodiversity,including similarity and connected status of the vegetation types SILi = 2z/(x + y) and species numbers SIc = 2z/(x + y) among different nature reserves.The quality refers to the stability of biodiversity,including relative species richness index RSLi = d/dmax,relative vegetation richness index RVLi =Dv/Dmaxv,fastness to invasion species fLi = 1-Si/St,weighted values,representativeness and vulnerability of special vegetations,special species,CITES species and rare species as the protected targets.

  16. Sustainably connecting children with nature: an exploratory study of nature play area visitor impacts and their management

    Science.gov (United States)

    Browning, Matthew H.E.M.; Marion, Jeffrey L.; Gregoire, Timothy G.

    2013-01-01

    Parks are developing nature play areas to improve children's health and “connect” them with nature. However, these play areas are often located in protected natural areas where managers must balance recreation with associated environmental impacts. In this exploratory study, we sought to describe these impacts. We also investigated which ages, gender, and play group sizes most frequently caused impact and where impacts most frequently occur. We measured the lineal and aerial extent and severity of impacts at three play areas in the eastern United States. Methods included soil and vegetation loss calculations, qualitative searches and tree and shrub damage classifications. Additionally, we observed 12 h of play at five play areas. Results showed that measurable negative impacts were caused during 33% of the time children play. On average, 76% of groundcover vegetation was lost at recreation sites and 100% was lost at informal trails. In addition, approximately half of all trees and shrubs at sites were damaged. Meanwhile, soil exposure was 25% greater on sites and trails than at controls. Boys and small group sizes more frequently caused impact, and informal recreation sites were most commonly used for play. No statistically significant correlations were found between age or location and impact frequency. Managers interested in developing nature play areas should be aware of, but not deterred by these impacts. The societal benefits of unstructured play in nature may outweigh the environmental costs. Recommended management strategies include selecting impact-resistant sites, improving site resistance, promoting low impact practices, and managing adaptively.

  17. Preferential flow paths and heat pipes: Results from laboratory experiments on heat-driven flow in natural and artificial rock fractures

    Energy Technology Data Exchange (ETDEWEB)

    Kneafsey, T.J.; Pruess, K. [Lawrence Berkeley National Lab., CA (United States). Earth Sciences Div.

    1997-06-01

    Water flow in fractures under the conditions of partial saturation and thermal drive may lead to fast flow along preferential localized pathways and heat pipe conditions. Water flowing in fast pathways may ultimately contact waste packages at Yucca Mountain and transport radionuclides to the accessible environment. Sixteen experiments were conducted to visualize liquid flow in glass fracture models, a transparent epoxy fracture replica, and a rock/replica fracture assembly. Spatially resolved thermal monitoring was performed in seven of these experiments to evaluate heat-pipe formation. Depending on the fracture apertures and flow conditions, various flow regimes were observed including continuous rivulet flow for high flow rates, intermittent rivulet flow and drop flow for intermediate flow rates, and film flow for low flow rates and wide apertures. These flow regimes were present in both fracture models and in the replica of a natural fracture. Heat-pipe conditions indicated by low thermal gradients were observed in five experiments. Conditions conducive to heat-pipe formation include an evaporation zone, condensation zone, adequate space for vapor and liquid to travel, and appropriate fluid driving forces. In one of the two experiments where heat pipe conditions were not observed, adequate space for liquid-vapor counterflow was not provided. Heat pipe conditions were not established in the other, because liquid flow was inadequate to compensate for imbibition and the quantity of heat contained within the rock.

  18. Optimal design of compact and connected nature reserves for multiple species.

    Science.gov (United States)

    Wang, Yicheng; Önal, Hayri

    2016-04-01

    When designing a conservation reserve system for multiple species, spatial attributes of the reserves must be taken into account at species level. The existing optimal reserve design literature considers either one spatial attribute or when multiple attributes are considered the analysis is restricted only to one species. We built a linear integer programing model that incorporates compactness and connectivity of the landscape reserved for multiple species. The model identifies multiple reserves that each serve a subset of target species with a specified coverage probability threshold to ensure the species' long-term survival in the reserve, and each target species is covered (protected) with another probability threshold at the reserve system level. We modeled compactness by minimizing the total distance between selected sites and central sites, and we modeled connectivity of a selected site to its designated central site by selecting at least one of its adjacent sites that has a nearer distance to the central site. We considered structural distance and functional distances that incorporated site quality between sites. We tested the model using randomly generated data on 2 species, one ground species that required structural connectivity and the other an avian species that required functional connectivity. We applied the model to 10 bird species listed as endangered by the state of Illinois (U.S.A.). Spatial coherence and selection cost of the reserves differed substantially depending on the weights assigned to these 2 criteria. The model can be used to design a reserve system for multiple species, especially species whose habitats are far apart in which case multiple disjunct but compact and connected reserves are advantageous. The model can be modified to increase or decrease the distance between reserves to reduce or promote population connectivity.

  19. An integrated profile of natural fractures in gas-bearing shale complex (Pomerania, Poland): based on structural profiling of oriented core and borehole logging data.

    Science.gov (United States)

    Bobek, Kinga; Jarosiński, Marek; Stadtmuller, Marek; Pachytel, Radomir; Lis-Śledziona, Anita

    2016-04-01

    Natural fractures in gas-bearing shales has significant impact on reservoir stimulation and increase of exploitation. Density of natural fractures and their orientation in respect to the maximum horizontal stress are crucial for propagation of technological hydraulic fractures. Having access to continuous borehole core profile and modern geophysical logging from several wells in the Pomeranian part of the Early Paleozoic Baltic Basin (Poland) we were able to compare the consistency of structural interpretation of several data sets. Although, final aim of our research is to optimize the method of fracture network reconstruction on a reservoir scale, at a recent stage we were focused on quantitative characterization of tectonic structures in a direct vicinity of boreholes. The data we have, cover several hundred meters long profiles of boreholes from the Ordovician and Silurian shale complexes. Combining different sets of data we broaden the scale of observation from borehole core (5 cm radius), through XRMI scan of a borehole wall (10 cm radius), up to penetration of a signal of an acoustic dipole logging (several tens of cm range). At the borehole core we examined the natural tectonic structures and mechanically significant features, like: mineral veins, fractured veins, bare fractures, slickensides, fault zones, stylolites, bedding plane and mechanically contrasting layers. We have also noticed drilling-induced features like centerline fractures and core disking, controlled by a recent tectonic stress. We have measured the orientation of fractures, their size, aperture and spacing and also describe the character of veins and tried to determine the stress regime responsible for fault slippage and fracture propagation. Wide range of analyzed features allowed us to discriminate fracture sets and reconstruct tectonic evolution of the complex. The most typical for analyzed shale complexes are steep and vertical strata-bound fractures that create an orthogonal joint

  20. Natural Learning for a Connected World: Education, Technology, and the Human Brain

    Science.gov (United States)

    Caine, Renate N.; Caine, Geoffrey

    2011-01-01

    Why do video games fascinate kids so much that they will spend hours pursuing a difficult skill? Why don't they apply this kind of intensity to their schoolwork? These questions are answered by the authors who pioneered brain/mind learning with the publication of "Making Connections: Teaching and the Human Brain". In their new book, "Natural…

  1. Natural Learning for a Connected World: Education, Technology, and the Human Brain

    Science.gov (United States)

    Caine, Renate N.; Caine, Geoffrey

    2011-01-01

    Why do video games fascinate kids so much that they will spend hours pursuing a difficult skill? Why don't they apply this kind of intensity to their schoolwork? These questions are answered by the authors who pioneered brain/mind learning with the publication of "Making Connections: Teaching and the Human Brain". In their new book, "Natural…

  2. Multiple-point statistical prediction on fracture networks at Yucca Mountain

    Energy Technology Data Exchange (ETDEWEB)

    Liu, X.Y; Zhang, C.Y.; Liu, Q.S.; Birkholzer, J.T.

    2009-05-01

    In many underground nuclear waste repository systems, such as at Yucca Mountain, water flow rate and amount of water seepage into the waste emplacement drifts are mainly determined by hydrological properties of fracture network in the surrounding rock mass. Natural fracture network system is not easy to describe, especially with respect to its connectivity which is critically important for simulating the water flow field. In this paper, we introduced a new method for fracture network description and prediction, termed multi-point-statistics (MPS). The process of the MPS method is to record multiple-point statistics concerning the connectivity patterns of a fracture network from a known fracture map, and to reproduce multiple-scale training fracture patterns in a stochastic manner, implicitly and directly. It is applied to fracture data to study flow field behavior at the Yucca Mountain waste repository system. First, the MPS method is used to create a fracture network with an original fracture training image from Yucca Mountain dataset. After we adopt a harmonic and arithmetic average method to upscale the permeability to a coarse grid, THM simulation is carried out to study near-field water flow in the surrounding waste emplacement drifts. Our study shows that connectivity or patterns of fracture networks can be grasped and reconstructed by MPS methods. In theory, it will lead to better prediction of fracture system characteristics and flow behavior. Meanwhile, we can obtain variance from flow field, which gives us a way to quantify model uncertainty even in complicated coupled THM simulations. It indicates that MPS can potentially characterize and reconstruct natural fracture networks in a fractured rock mass with advantages of quantifying connectivity of fracture system and its simulation uncertainty simultaneously.

  3. Multiple-point statistical prediction on fracture networks at Yucca Mountain

    Science.gov (United States)

    Liu, Xiaoyan; Zhang, Chengyuan; Liu, Quansheng; Birkholzer, Jens

    2009-05-01

    In many underground nuclear waste repository systems, such as Yucca Mountain project, water flow rate and amount of water seepage into the waste emplacement drifts are mainly determined by hydrological properties of fracture network in the surrounding rock mass. Natural fracture network system is not easy to describe, especially with respect to its connectivity which is critically important for simulating the water flow field. In this paper, we introduced a new method for fracture network description and prediction, termed multi-point-statistics (MPS). The process of Multi-point Statistical method is to record multiple-point statistics concerning the connectivity patterns of fracture network from a known fracture map, and to reproduce multiple-scale training fracture patterns in a stochastic manner, implicitly and directly. It is applied to fracture data to study flow field behavior at Yucca Mountain waste repository system. First, MPS method is used to create fracture network with original fracture training image from Yucca Mountain dataset. After we adopt a harmonic and arithmetic average method to upscale the permeability to a coarse grid, THM simulation is carried out to study near-field water flow in surrounding rock of waste emplacement drifts. Our study shows that connectivity or pattern of fracture network can be grasped and reconstructed by Multi-Point-Statistical method. In theory, it will lead to better prediction of fracture system characteristics and flow behavior. Meanwhile, we can obtain variance from flow field, which gives us a way to quantify uncertainty of models even in complicated coupled THM simulation. It indicates that Multi-Point Statistics is a potential method to characterize and reconstruct natural fracture network in a fractured rock mass with advantages of quantifying connectivity of fracture system and its simulation uncertainty simultaneously.

  4. The nature of annual lamination in carbonate flowstones from non-karstic fractures, Vinschgau (northern Italy)

    Science.gov (United States)

    Koltai, Gabriella; Spötl, Christoph; Luetscher, Marc; Cheng, Hai; Barrett, Samuel J.; Müller, Wolfgang

    2017-04-01

    The Vinschgau is an inneralpine valley in the Southern Alps, whose steep flanks are comprised of strongly sheared gneisses and schists affected by deep-seated gravitational slope deformations. The south-facing slope of the Vinschgau (Sonnenberg) hosts a fractured slope aquifer that is characterized by high amounts of dissolved solids, which reflect long residence times and water-rock interactions driven by sulphide oxidation. In the shallow parts of the aquifer calcite and aragonite flowstones form as a result of evaporation driven by high air and soil temperatures. Both unlaminated and regularly laminated (ca. 5%) flowstone types occur, the latter being a rare example in fracture-filling carbonates hosted in crystalline rocks. A stable isotope, petrographic and trace element study combined with U-Th dating was undertaken to disentangle the processes controlling lamina formation in these unusual speleothems. A succession of darker and lighter laminae forms distinct macroscopic couplets (0.2-2 mm wide) in three of the samples, while one sample comprises alternating white and translucent laminae. Microscopically, the darker and white laminae show a higher abundance of opaque particles, whose organic origin is confirmed by their strong epifluorescence. The crystal fabric, dominated by the fascicular-optic type, shows no change across lamina boundaries, neither was any consistent correlation between the lamina couplets and the stable isotope values observed. The calcite exhibits regular δ18O oscillations with an amplitude of up to 1.2 ‰, while apart from one sample, δ13C lacks such a regular pattern. All samples exhibit regular, low-amplitude Mg, Sr, Ba and U cycles. In three samples Mg shows oscillations similar to the δ18O cycles in their frequency, but opposite in phasing. δ18O and Mg oscillations are primarily attributed to surface temperature variations that are transmitted to the shallow subsurface by thermal conduction. Low-amplitude trace element cycles

  5. A multi-scale case study of natural fracture systems in outcrops and boreholes with applications to reservoir modelling

    NARCIS (Netherlands)

    Taal-van Koppen, J.K.J.

    2008-01-01

    Fractured reservoirs are notoriously difficult to characterize because the resolution of seismic data is too low to detect fractures whereas borehole data is detailed but sparse. Therefore, outcrops can be of great support in gaining knowledge of the three-dimensional geometry of fracture networks,

  6. Bending strength and fracture surface topography of natural fiber-reinforced shell for investment casting process

    Directory of Open Access Journals (Sweden)

    Kai Lu

    2016-05-01

    Full Text Available In order to improve the properties of silica sol shell for investment casting process, various contents of cattail fibers were added into the slurry to prepare a fiber-reinforced shell in the present study. The bending strength of fiber-reinforced shell was investigated and the fracture surfaces of shell specimens were observed using SEM. It is found that the bending strength increases with the increase of fiber content, and the bending strength of a green shell with 1.0 wt.% fiber addition increases by 44% compared to the fiber-free shell. The failure of specimens of the fiber-reinforced green shell results from fiber rupture and debonding between the interface of fibers and adhesive under the bending load. The micro-crack propagation in the matrix is inhibited by the micro-holes for ablation of fibers in specimens of the fiber-reinforced shell during the stage of being fired. As a result, the bending strength of specimens of the fired shell had no significant drop. Particularly, the bending strength of specimens of the fired shell reinforced with 0.6wt.% fiber reached the maximum value of 4.6 MPa.

  7. A social science perspective on the forest preserves: Seven virtues for connecting people and nature

    Science.gov (United States)

    Paul H. Gobster

    2015-01-01

    How do people perceive and value urban green space? In what ways do people's perceptions and values of urban nature affect their use and experience of parks, forest preserves, and other green space types? Knowing this information, how can green space planners, managers, and decision makers facilitate a better "fit" between people and nature in urban...

  8. Students' Understanding of Connections between Human Engineered and Natural Environmental Systems

    Science.gov (United States)

    Tsurusaki, Blakely K.; Anderson, Charles W.

    2010-01-01

    This research draws on developments in educational research where "learning progressions" are emerging as a strategy for synthesizing research on science learning and applying that research to policy and practice, and advances in the natural sciences, where "interdisciplinary research on coupled human and natural systems" has become increasingly…

  9. Connecting Science and Mathematics: The Nature of Scientific and Statistical Hypothesis Testing

    Science.gov (United States)

    Lawson, Anton E.; Oehrtman, Michael; Jensen, Jamie

    2008-01-01

    Confusion persists concerning the roles played by scientific hypotheses and predictions in doing science. This confusion extends to the nature of scientific and statistical hypothesis testing. The present paper utilizes the "If/and/then/Therefore" pattern of hypothetico-deductive (HD) reasoning to explicate the nature of both scientific and…

  10. Pressure Transient Analysis and Flux Distribution for Multistage Fractured Horizontal Wells in Triple-Porosity Reservoir Media with Consideration of Stress-Sensitivity Effect

    Directory of Open Access Journals (Sweden)

    Jingjing Guo

    2015-01-01

    Full Text Available Triple-porosity model is usually adopted to describe reservoirs with multiscaled pore spaces, including matrix pores, natural fractures, and vugs. Multiple fractures created by hydraulic fracturing can effectively improve the connectivity between existing natural fractures and thus increase well deliverability. However, little work has been done on pressure transient behavior of multistage fractured horizontal wells in triple-porosity reservoirs. Based on source/sink function method, this paper presents a triple-porosity model to investigate the transient pressure dynamics and flux distribution for multistage fractured horizontal wells in fractured-vuggy reservoirs with consideration of stress-dependent natural fracture permeability. The model is semianalytically solved by discretizing hydraulic fractures and Pedrosa’s transformation, perturbation theory, and integration transformation method. Type curves of transient pressure dynamics are generated, and flux distribution among hydraulic fractures for a fractured horizontal well with constant production rate is also discussed. Parametric study shows that major influential parameters on transient pressure responses are parameters pertinent to reservoir properties, interporosity mass transfer, and hydraulic fractures. Analysis of flux distribution indicates that flux density gradually increases from the horizontal wellbore to fracture tips, and the flux contribution of outermost fractures is higher than that of inner fractures. The model can also be extended to optimize hydraulic fracture parameters.

  11. Adaptive neighbor connection for PRMs: A natural fit for heterogeneous environments and parallelism

    KAUST Repository

    Ekenna, Chinwe

    2013-11-01

    Probabilistic Roadmap Methods (PRMs) are widely used motion planning methods that sample robot configurations (nodes) and connect them to form a graph (roadmap) containing feasible trajectories. Many PRM variants propose different strategies for each of the steps and choosing among them is problem dependent. Planning in heterogeneous environments and/or on parallel machines necessitates dividing the problem into regions where these choices have to be made for each one. Hand-selecting the best method for each region becomes infeasible. In particular, there are many ways to select connection candidates, and choosing the appropriate strategy is input dependent. In this paper, we present a general connection framework that adaptively selects a neighbor finding strategy from a candidate set of options. Our framework learns which strategy to use by examining their success rates and costs. It frees the user of the burden of selecting the best strategy and allows the selection to change over time. We perform experiments on rigid bodies of varying geometry and articulated linkages up to 37 degrees of freedom. Our results show that strategy performance is indeed problem/region dependent, and our adaptive method harnesses their strengths. Over all problems studied, our method differs the least from manual selection of the best method, and if one were to manually select a single method across all problems, the performance can be quite poor. Our method is able to adapt to changing sampling density and learns different strategies for each region when the problem is partitioned for parallelism. © 2013 IEEE.

  12. High Energy Gas Fracturing in Deep Reservoir

    Institute of Scientific and Technical Information of China (English)

    Zhang Qiangde; Zhao Wanxiang; Wang Faxuan

    1994-01-01

    @@ Introduction The HEGF technology has many merits such as low cost, simple work conditions, treating the thin reservoir without layer dividing tools, no contamination to the reservoirs and connections with more natural fractures. So it is suitable to treat thin reservoirs,water and acid senstive reservoirs and the reserviors with natural fissures and also suitable to evaluate the production test of new wells, blocking removing treatment, increasing injection treatment and the treatment for the hydrofracturing well with some productivity.

  13. Connecting food environments and health through the relational nature of aesthetics: gaining insight through the community gardening experience.

    Science.gov (United States)

    Hale, James; Knapp, Corrine; Bardwell, Lisa; Buchenau, Michael; Marshall, Julie; Sancar, Fahriye; Litt, Jill S

    2011-06-01

    Current environmental and health challenges require us to identify ways to better align aesthetics, ecology, and health. At the local level, community gardens are increasingly praised for their therapeutic qualities. They also provide a lens through which we can explore relational processes that connect people, ecology and health. Using key-informant interview data, this research explores gardeners' tactile, emotional, and value-driven responses to the gardening experience and how these responses influence health at various ecological levels (n = 67 participants, 28 urban gardens). Our findings demonstrate that gardeners' aesthetic experiences generate meaning that encourages further engagement with activities that may lead to positive health outcomes. Gardeners directly experience nearby nature by 'getting their hands dirty' and growing food. They enjoy the way vegetables taste and form emotional connections with the garden. The physical and social qualities of garden participation awaken the senses and stimulate a range of responses that influence interpersonal processes (learning, affirming, expressive experiences) and social relationships that are supportive of positive health-related behaviors and overall health. This research suggests that the relational nature of aesthetics, defined as the most fundamental connection between people and place, can help guide community designers and health planners when designing environment and policy approaches to improve health behaviors.

  14. Utilizing a Health Impact Assessment (HIA) to Connect Natural Resource Management and Community

    Science.gov (United States)

    Marrying scientific and health research with natural resource management should be a straightforward process. However, differences in purpose, goals, language, levels of detail and implementation authority between the scientists who conduct research and resource managers who plan...

  15. Utilizing a Health Impact Assessment (HIA) to Connect Natural Resource Management and Community(presentation)

    Science.gov (United States)

    Marrying scientific and health research with natural resource management should be a straightforward process. However, differences in purpose, goals, language, levels of detail and implementation authority between the scientists who conduct research and resource managers who plan...

  16. Habit as a Connecting Nature, Mind and Culture in CS Peirce's Semiotic Pragmaticism

    DEFF Research Database (Denmark)

    Brier, Søren

    2017-01-01

    theories and models. The end of research in a certified truth is an ideal far away in the future [2]. Furthermore he was not a physicalistic material mechanists but a process philosopher and an evolutionary synechist [3]. This means that he thought that mind and matter was connected in a continuum...... in Newton’s theory of motion was reversible. Time had no arrow. But in Peirce’s cosmogony change is at the basis as Firstness is imbued with the tendency to take habits and time therefore has an arrow and is irreversible and therefore what the laws manifested as the universe develop. This was unthinkable...

  17. Nature, Genetics and the Biophilia Connection: Exploring Linkages with Social Work Values and Practice

    Directory of Open Access Journals (Sweden)

    Fred H. Besthorn

    2003-05-01

    Full Text Available Social work’s notion of environment and its environmental responsibilities has always been narrowly defined. The profession has tended to either neglect natural environmental issues or accept shallow, ecological conceptualizations of nature as something other, quite separate from the human enterprise and/or outside the reach of social work activity. The Biophilia Hypothesis, first articulated by Harvard biologist E.O.Wilson in 1984, offers social work as a fundamentally different view of the person/environment construct and argues for a primary shift in the way the profession views its relationship with the natural world. This article traces the conceptual development of the Biophilic theory and reviews pivotal empirical evidence explicitly arguing for the essential Biophilic premise that humans have acquired, through their long evolutionary history, a strong genetic predisposition for nature and natural settings. It offers key insights and examples for incorporating Biophilia into social work’s values and knowledge base and how it may impact the profession’s practice strategies and techniques.

  18. Soil networks become more connected and take up more carbon as nature restoration progresses

    DEFF Research Database (Denmark)

    Morriën, Elly; Hannula, S Emilia; Snoek, L Basten

    2017-01-01

    the course of nature restoration on abandoned arable land a compositional shift in soil biota, preceded by tightening of the belowground networks, corresponds with enhanced efficiency of carbon uptake. In mid- and long-term abandoned field soil, carbon uptake by fungi increases without an increase in fungal...... biomass or shift in bacterial-to-fungal ratio. The implication of our findings is that during nature restoration the efficiency of nutrient cycling and carbon uptake can increase by a shift in fungal composition and/or fungal activity. Therefore, we propose that relationships between soil food web...

  19. Guides to Sustainable Connections? Exploring Human-Nature Relationships among Wilderness Travel Leaders

    Science.gov (United States)

    Grimwood, Bryan S. R.; Haberer, Alexa; Legault, Maria

    2015-01-01

    This paper explores and critically interprets the role wilderness travel may play in fostering environmental sustainability. The paper draws upon two qualitative studies that sought to understand human-nature relationships as experienced by different groups of wilderness travel leaders in Canada. According to leaders involved in the studies,…

  20. Children's Participation in a Virtual Epidemic in the Science Classroom: Making Connections to Natural Infectious Diseases

    Science.gov (United States)

    Neulight, Nina; Kafai, Yasmin B.; Kao, Linda; Foley, Brian; Galas, Cathleen

    2007-01-01

    This study investigated students' understanding of a virtual infectious disease in relation to their understanding of natural infectious diseases. Two sixth-grade classrooms of students between the ages of 10 and 12 (46 students) took part in a participatory simulation of a virtual infectious disease, which was integrated into their science…

  1. Creative Connecting: Early Childhood Nature Journaling Sparks Wonder and Develops Ecological Literacy

    Science.gov (United States)

    Johnson, Kelly

    2014-01-01

    While nature journaling with elementary age children has recently increased in popularity, journaling with children of ages 2-6 is often overlooked. This article focuses specifically on why journaling is a valid practice in early childhood and the practitioner application of journaling techniques modified for the young child. Young children have…

  2. Children's Participation in a Virtual Epidemic in the Science Classroom: Making Connections to Natural Infectious Diseases

    Science.gov (United States)

    Neulight, Nina; Kafai, Yasmin B.; Kao, Linda; Foley, Brian; Galas, Cathleen

    2007-01-01

    This study investigated students' understanding of a virtual infectious disease in relation to their understanding of natural infectious diseases. Two sixth-grade classrooms of students between the ages of 10 and 12 (46 students) took part in a participatory simulation of a virtual infectious disease, which was integrated into their science…

  3. Connecting Self-Efficacy and Views about the Nature of Science in Undergraduate Research Experiences

    Science.gov (United States)

    Quan, Gina M.; Elby, Andrew

    2016-01-01

    Undergraduate research can support students' more central participation in physics. We analyze markers of two coupled shifts in participation: changes in students' views about the nature of science coupled to shifts in self-efficacy toward physics research. Students in the study worked with faculty and graduate student mentors on research projects…

  4. Connecting Model Species to Nature: Predator-Induced Long-Term Sensitization in "Aplysia Californica"

    Science.gov (United States)

    Mason, Maria J.; Watkins, Amanda J.; Wakabayashi, Jordann; Buechler, Jennifer; Pepino, Christine; Brown, Michelle; Wright, William G.

    2014-01-01

    Previous research on sensitization in "Aplysia" was based entirely on unnatural noxious stimuli, usually electric shock, until our laboratory found that a natural noxious stimulus, a single sublethal lobster attack, causes short-term sensitization. We here extend that finding by demonstrating that multiple lobster attacks induce…

  5. A possible FRB/GRB connection: towards a multi-wavelength campaign to unveil the nature of Fast Radio Bursts

    CERN Document Server

    Zhang, Bing

    2013-01-01

    The physical nature of Fast Radio Bursts (FRBs), a new type of cosmological transients discovered recently, is not known. It has been suggested that FRBs can be produced when a spinning supra-massive neutron star loses centrifugal support and collapses to a black hole. Here we suggest that such implosions can happen in supra-massive neutron stars shortly (hundreds to thousands of seconds) after their births, and an observational signature of such implosions may have been observed in the X-ray afterglows of some long and short gamma-ray bursts (GRBs). Within this picture, a small fraction of FRBs would be physically connected to GRBs. We discuss possible multi-wavelength electromagnetic signals and gravitational wave signals that might be associated with FRBs, and propose an observational campaign to unveil the physical nature of FRBs. In particular, we strongly encourage a rapid radio follow-up observation of GRBs starting from 100 s after GRB triggers.

  6. Soil networks become more connected and take up more carbon as nature restoration progresses

    Science.gov (United States)

    Morriën, Elly; Hannula, S. Emilia; Snoek, L. Basten; Helmsing, Nico R.; Zweers, Hans; de Hollander, Mattias; Soto, Raquel Luján; Bouffaud, Marie-Lara; Buée, Marc; Dimmers, Wim; Duyts, Henk; Geisen, Stefan; Girlanda, Mariangela; Griffiths, Rob I.; Jørgensen, Helene-Bracht; Jensen, John; Plassart, Pierre; Redecker, Dirk; Schmelz, Rűdiger M; Schmidt, Olaf; Thomson, Bruce C.; Tisserant, Emilie; Uroz, Stephane; Winding, Anne; Bailey, Mark J.; Bonkowski, Michael; Faber, Jack H.; Martin, Francis; Lemanceau, Philippe; de Boer, Wietse; van Veen, Johannes A.; van der Putten, Wim H.

    2017-01-01

    Soil organisms have an important role in aboveground community dynamics and ecosystem functioning in terrestrial ecosystems. However, most studies have considered soil biota as a black box or focussed on specific groups, whereas little is known about entire soil networks. Here we show that during the course of nature restoration on abandoned arable land a compositional shift in soil biota, preceded by tightening of the belowground networks, corresponds with enhanced efficiency of carbon uptake. In mid- and long-term abandoned field soil, carbon uptake by fungi increases without an increase in fungal biomass or shift in bacterial-to-fungal ratio. The implication of our findings is that during nature restoration the efficiency of nutrient cycling and carbon uptake can increase by a shift in fungal composition and/or fungal activity. Therefore, we propose that relationships between soil food web structure and carbon cycling in soils need to be reconsidered. PMID:28176768

  7. Connecting self-efficacy and views about the nature of science in undergraduate research experiences

    Science.gov (United States)

    Quan, Gina M.; Elby, Andrew

    2016-12-01

    Undergraduate research can support students' more central participation in physics. We analyze markers of two coupled shifts in participation: changes in students' views about the nature of science coupled to shifts in self-efficacy toward physics research. Students in the study worked with faculty and graduate student mentors on research projects while also participating in a seminar where they learned about research and reflected on their experiences. In classroom discussions and in clinical interviews, students described gaining more nuanced views about the nature of science, specifically related to who can participate in research and what participation in research looks like. This shift was coupled to gains in self-efficacy toward their ability to contribute to research; they felt like their contributions as novices mattered. We present two case studies of students who experienced coupled shifts in self-efficacy and views about nature-of-science shifts, and a case study of a student for whom we did not see either shift, to illustrate both the existence of the coupling and the different ways it can play out. After making the case that this coupling occurs, we discuss some potential underlying mechanisms. Finally, we use these results to argue for more nuanced interpretations of self-efficacy measurements.

  8. Constraints to connecting children with nature--Survey of U.S. Fish and Wildlife Service employees sponsored by the National Conservation Training Center, Division of Education Outreach

    Science.gov (United States)

    Ratz, Joan M.; Schuster, Rudy M.

    2011-01-01

    The U.S. Fish and Wildlife Service (FWS) names "connecting people with nature" as one of its top six priorities in the online Service Employee Pocket Guide. The National Conservation Training Center (NCTC) took the initiative to identify issues that impede greater progress in addressing constraints to connecting children with nature. The Division of Education Outreach at NCTC formed a working relation with the Policy Analysis and Science Assistance branch of the U.S. Geological Survey to conduct a study on these issues. To meet the objectives of the study, a survey of a sample of FWS employees was conducted. This report includes the description of how the survey was developed and administered, how the data were analyzed, and a discussion of the survey results. The survey was developed based on published literature and incorporated input from two working groups of professionals focused on the issue of connecting children with nature. Although the objective as stated by the FWS is to connect people with nature, the survey primarily focused on connecting children, rather than all people, with nature. The four primary concepts included on the survey were interpretation of how the FWS defined "connection" as part of its mission, perceived success with outreach, constraints to connecting children with nature, and importance of connecting children with nature. The survey was conducted online using KeySurvey© software. The survey was sent to 604 FWS employees. Responses were received from 320 employees. The respondents represented diversity in regions, tenure, wage/grade level, job series, supervisory status, and involvement with education and outreach activities. The key findings of the survey are as follows: * FWS employees believe they as individuals and the agency are successful now and will be more successful in the future in connecting children with nature. * FWS employees believe that there are many outcomes that are relevant to the FWS objective to connect people

  9. A Handbook for the Application of Seismic Methods for Quantifying Naturally Fractured Gas Reservoirs in the San Juan Basin, New Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Majer, Ernest; Queen, John; Daley, Tom; Fortuna, Mark; Cox, Dale; D' Onfro, Peter; Goetz, Rusty; Coates, Richard; Nihei, Kurt; Nakagawa, Seiji; Myer, Larry; Murphy, Jim; Emmons, Charles; Lynn, Heloise; Lorenz, John; LaClair, David; Imhoff, Mathias; Harris, Jerry; Wu, Chunling; Urban, Jame; Maultzsch, Sonja; Liu, Enru; Chapman, Mark; Li, Xiang-Yang

    2004-09-28

    A four year (2000-2004) comprehensive joint industry, University and National Lab project was carried out in a 20 square mile area in a producing gas field in the Northwest part of the San Juan Basin in New Mexico to develop and apply multi-scale seismic methods for detecting and quantifying fractures in a naturally fractured gas reservoirs. 3-D surface seismic, multi-offset 9-C VSP, 3-C single well seismic, and well logging data were complemented by geologic/core studies to model, process and interpret the data. The overall objective was to determine the seismic methods most useful in mapping productive gas zones. Data from nearby outcrops, cores, and well bore image logs suggest that natural fractures are probably numerous in the subsurface reservoirs at the site selected and trend north-northeast/south-southwest despite the apparent dearth of fracturing observed in the wells logged at the site (Newberry and Moore wells). Estimated fracture spacing is on the order of one to five meters in Mesaverde sandstones, less in Dakota sandstones. Fractures are also more frequent along fault zones, which in nearby areas trend between north-northeast/south-southwest and northeast-southwest and are probably spaced a mile or two apart. The maximum, in situ, horizontal, compressive stress in the vicinity of the seismic test site trends approximately north-northeast/south-southwest. The data are few but they are consistent. The seismic data present a much more complicated picture of the subsurface structure. Faulting inferred from surface seismic had a general trend of SW - NE but with varying dip, strike and spacing. Studies of P-wave anisotropy from surface seismic showed some evidence that the data did have indications of anisotropy in time and amplitude, however, compared to the production patterns there is little correlation with P-wave anisotropy. One conclusion is that the surface seismic reflection data are not detecting the complexity of fracturing controlling the

  10. Fugitive Emissions from Conventional and Hydraulically Fractured Natural Gas Developments in Western Canada

    Science.gov (United States)

    Atherton, E. E.; Risk, D. A.; Lavoie, M.; Marshall, A. D.; Baillie, J.; Williams, J. P.

    2015-12-01

    Presently, fugitive emissions released into the atmosphere during the completion and production of oil and gas wells are poorly regulated within Canada. Some possible upstream sources of these emissions include flowback during well completions, liquid unloading, chemical injection pumps, and equipment leaks. The environmental benefits of combusting natural gas compared to oil or coal are negated if methane leakages surpass 3.2% of total production, so it is important to have a thorough understanding of these fugitive emissions. This study compares atmospheric leakage pathways of methane and other fugitive gases in both conventional and unconventional oil and gas developments in Western Canada to help fill this knowledge gap. Over 5000 kilometers of mobile survey campaigns were completed in carefully selected developments in the Montney shale play in British Columbia, and in conventional oil fields in Alberta. These sites are developed by more than 25 different operators. High precision laser and UV fluorescence gas analyzers were used to gather geolocated trace gas concentrations at a frequency of 1 Hz while driving. These data were processed with an adaptive technique to compensate for fluctuations in background concentrations for each gas. The residual excess concentrations were compositionally fingerprinted on the basis of the expected gas ratios for potential emission sites in order to definitively attribute anomalies to infrastructural leak sources. Preliminary results from the mobile surveys of both conventional and unconventional oil and gas sites are presented here. Pathways of methane and other fugitive gases are mapped to their respective sources, identifying common causes of emissions leaks across the oil and gas industry. This is the first bottom-up study of fugitive emissions from Canadian energy developments to produce publicly available data. These findings are significant to operators interested in lowering emissions for economic benefit, as well as

  11. Methane Emissions from Hydraulically Fractured Natural Gas Developments in Northeastern British Columbia

    Science.gov (United States)

    Atherton, E. E.; Risk, D. A.; Fougère, C. R.; Lavoie, M.; Marshall, A. D.; Werring, J.

    2016-12-01

    If we are to attain the recent North American goals to reduce methane (CH4) emissions, we must understand emission patterns across developments of different types. In this study we quantified the incidence of CH4 emissions from unconventional natural gas infrastructure accessing the Montney play in British Columbia, Canada. We used mobile surveying to collect CH4 and CO2 measurements over 11,000 km of survey campaigns. Our routes brought us past more than 1600 unique well pads and facilities, and we repeated the six routes 7-10 times during summer (2015) and winter (2016) to explore temporal variability. Well pads and facilities were considered probable emission sources only if they were upwind by 500 m or less from the survey vehicle, and on-road concentrations were in excess of local background. In the summer campaigns we found that 47% of individual active production wells emitted CH4-rich plumes, and most of them emitted persistently across repeat surveys. Older infrastructure tended to emit more frequently (per unit), with comparable severity to younger infrastructure in terms of measured excess concentrations on-road. About 26% of abandoned wells were also found to be emitting. Extrapolating our emission incidence values across all abandoned oil and gas infrastructure in the BC portion of the Montney, we estimate that there are more than 550 abandoned wells in this area that could be emitting CH4-rich plumes. The results of this study suggest that analyzing emitting infrastructure by ages and operational differences can help delineate emission trends. Considering the recent industry downturn, our results also highlight the importance of focusing emission reduction efforts on abandoned and suspended infrastructure, as well as active. This is the first bottom-up monitoring study of fugitive emissions in the Canadian energy sector, and the results can be used to inform policy development to reduce energy-related emissions.

  12. Review: Natural tracers in fractured hard-rock aquifers in the Austrian part of the Eastern Alps—previous approaches and future perspectives for hydrogeology in mountain regions

    Science.gov (United States)

    Hilberg, Sylke

    2016-08-01

    Extensive in-depth research is required for the implementation of natural tracer approaches to hydrogeological investigation to be feasible in mountainous regions. This review considers the application of hydrochemical and biotic parameters in mountain regions over the past few decades with particular reference to the Austrian Alps, as an example for alpine-type mountain belts. A brief introduction to Austria's hydrogeological arrangement is given to show the significance of fractured hard-rock aquifers for hydrogeological science as well as for water supply purposes. A literature search showed that research concerning fractured hard-rock aquifers in Austria is clearly underrepresented to date, especially when taking the abundance of this aquifer type and the significance of this topic into consideration. The application of abiotic natural tracers (hydrochemical and isotope parameters) is discussed generally and by means of examples from the Austrian Alps. The potential of biotic tracers (microbiota and meiofauna) is elucidated. It is shown that the meiofauna approach to investigating fractured aquifers has not yet been applied in the reviewed region, nor worldwide. Two examples of new approaches in mountainous fractured aquifers are introduced: (1) use of CO2 partial pressure and calcite saturation of spring water to reconstruct catchments and flow dynamics (abiotic approach), and, (2) consideration of hard-rock aquifers as habitats to reconstruct aquifer conditions (biotic approach).

  13. The connection between natural gas hydrate and bottom-simulating reflectors

    Science.gov (United States)

    Majumdar, Urmi; Cook, Ann E.; Shedd, William; Frye, Matthew

    2016-07-01

    Bottom-simulating reflectors (BSRs) on marine seismic data are commonly used to identify the presence of natural gas hydrate in marine sediments, although the exact relationship between gas hydrate and BSRs is undefined. To clarify this relationship we compile a data set of probable gas hydrate occurrence as appraised from well logs of 788 industry wells in the northern Gulf of Mexico. We combine the well log data set with a data set of BSR distribution in the same area identified from 3-D seismic data. We find that a BSR increases the chances of finding gas hydrate by 2.6 times as opposed to drilling outside a BSR and that the wells within a BSR also contain thicker and higher resistivity hydrate accumulations. Even so, over half of the wells drilled through BSRs have no detectable gas hydrate accumulations and gas hydrate occurrences and BSRs do not coincide in most cases.

  14. Natural and anthropogenic change in the morphology and connectivity of tidal channels of southwest Bangladesh

    Science.gov (United States)

    Wilson, C.; Goodbred, S. L., Jr.; Wallace Auerbach, L.; Ahmed, K. R.; Small, C.; Sams, S. E.

    2014-12-01

    Over the last century, land use changes in the Ganges-Brahmaputra tidal delta have transformed >5000 km2 of intertidal mangrove forest to densely inhabited, agricultural islands that have been embanked to protect against tides and storm surges (i.e., polders). More recently, the conversion of rice paddies to profitable shrimp aquaculture has become increasingly widespread. Recent field studies documented that poldering in southwest Bangladesh has resulted in an elevation deficit relative to that of the natural mangrove forests and mean high water (MHW). The offset is a function of lost sedimentation, enhanced compaction, and an effective rise in MHW from tidal amplification. The morphologic adjustment of the tidal channel network to these perturbations, however, has gone largely undocumented. One effect has been the shoaling of many channels due to decreases in fluvial discharge and tidal prism. We document a previously unrecognized anthropogenic component: the widespread closure of large conduit tidal channels for land reclamation and shrimp farming. GIS analysis of historical Landsat and Google Earth imagery within six 1000 km2 study areas reveals that the tidal network in the natural Sundarbans mangrove forest has remained relatively constant since the 1970s, while significant changes are observed in human-modified areas. Construction of the original embankments removed >1000 km of primary tidal creeks, and >80 km2 of land has been reclaimed outside of polders through the closure of formerly active tidal channels (decrease in mean channel width from 256±91 m to 25±10 m). Tidal restriction by large sluice gates is prevalent, favoring local channel siltation. Furthermore, severing the intertidal platform and large conduit channels from the tidal network has had serious repercussions, such as increased lateral migration and straightening of the remaining channels. Where banklines have eroded, the adjacent embankments appear to be more vulnerable to failure, as

  15. Training of panellists for the sensory control of bottled natural mineral water in connection with water chemical properties.

    Science.gov (United States)

    Rey-Salgueiro, Ledicia; Gosálbez-García, Aitana; Pérez-Lamela, Concepción; Simal-Gándara, Jesús; Falqué-López, Elena

    2013-11-01

    As bottled mineral water market is increasing in the world (especially in emergent and developed countries), the development of a simple protocol to train a panel to evaluate sensory properties would be a useful tool for natural drinking water industry. A sensory protocol was developed to evaluate bottled natural mineral water (17 still and 10 carbonated trademarks). The tasting questionnaire included 13 attributes for still water plus overall impression and they were sorted by: colour hues, transparency and brightness, odour/aroma and taste/flavour/texture and 2 more for carbonated waters (bubbles and effervescence). The training lasted two months with, at least, 10 sessions, was adequate to evaluate bottled natural mineral water. To confirm the efficiency of the sensory training procedure two sensory groups formed the whole panel. One trained panel (6 persons) and one professional panel (6 sommeliers) and both participated simultaneously in the water tasting evaluation of 3 sample lots. Similar average scores obtained from trained and professional judges, with the same water trademarks, confirmed the usefulness of the training protocol. The differences obtained for trained panel in the first lot confirm the necessity to train always before a sensory procedure. A sensory water wheel is proposed to guide the training in bottled mineral water used for drinking, in connection with their chemical mineral content.

  16. Average reservoir pressure determination for homogeneous and naturally fractured formations from multi-rate testing with the TDS technique

    Energy Technology Data Exchange (ETDEWEB)

    Escobar, Freddy Humberto; Ibagon, Oscar Eduardo; Montealegre-M, Matilde [Universidad Surcolombiana, Av. Pastrana-Cra. 1, Neiva, Huila (Colombia)

    2007-11-15

    Average reservoir pressure is an important parameter which is utilized in almost all reservoir and production engineering studies. It also plays a relevant role in the majority of well intervention jobs, field appraisal, well sizing and equipment and surface facilities design. The estimation of the average reservoir pressure is normally obtained from buildup tests. However, it has a tremendous economic impact caused by shutting-in the well during the entire test. Since buildup tests are the most particular case of multi-rate tests, these are also used for estimation of the average reservoir pressure. Among them, two-rate tests present drawbacks because it is operationally difficult to keep constant the flow rates. Conventional methods for determination of the average reservoir pressure can be readily extended to multi-rate tests once the rigorous time is converted to equivalent time by time superposition. In this article a new, easy and practical methodology is presented for the determination of the average pressure in both homogeneous and naturally fractured reservoirs from multi-rate tests conducted in vertical oil wells located inside a close drainage region. The methodology which follows the philosophy of the TDS technique uses a normalized pressure and pressure derivative point found on any arbitrary point during the pseudosteady-state flow regime to readily provide the average reservoir pressure value. For verification of the effectiveness of the proposed solution, several field and simulated examples were worked out. We found that the average reservoir pressure results obtained from the proposed methodology match very well with those estimated from either conventional techniques or simulations. (author)

  17. The nature of fracturing and stress distribution in quartzite around the 1128-M (3700-FT) level of the crescent mine, Coeur d'Alene mining district, Idaho

    Science.gov (United States)

    Miller, C.H.; Skinner, E.H.

    1980-01-01

    Silver and copper are the principal ores mined from the quartzite at the Crescent mine. Both the main ore-bearing veins and foliation in the quartzite are parallel to the nearly vertical formational contacts. Anisotropy of the quartzite is indicated by both dynamic and static tests. Disking and breakage of core from holes perpendicular to the foliation are about twice what they are in core from holes parallel to foliation. Natural cleavage as well as slabbing and blasting fractures around the tunnels are also controlled by the foliation. Extensive overcore deformation measurements indicate that most of the influence of the tunnels on the "free" stress field is between the rib and a depth of 2.7 m (1 tunnel diameter). The maximum principal stress axis in the free field is nearly horizontal; its magnitude is not much greater than the vertical component and calculations indicate a nearly hydrostatic free stress field. Stress considerably greater than the free field was measured between about 0.3-2.7 m behind the rib and is caused by a transfer of load from above the tunnel opening. Peak stress is in the vertical direction and about 1.7 m behind the rib. An air-injection survey shows that high permeabilities are confined to the highly fractured annulus around a tunnel to a depth of at least 0.6 m. Air-injection measurements could be taken in the interval of about 0.6-1.8 m, but more fractures with high permeabilities may also be present in the annulus from about 0.6-1.2 m. Permeabilities measured deeper than about 1.8 m by the air-injection technique are either very low or nonexistent. The absence of open and noncontinuous fractures beyond about 1.8 m is also indicated by very low porosities and permeabilities of core, very high stresses (which presumably would close fractures), the lack of stains or secondary fillings in disking fractures, a conspicuous lack of ground water in the tunnels, and the fact that fractures encountered in an experimental 0.9-m tunnel did not

  18. Optimizing for Large Planar Fractures in Multistage Horizontal Wells in Enhanced Geothermal Systems Using a Coupled Fluid and Geomechanics Simulator

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Xiexiaomen; Tutuncu, Azra; Eustes, Alfred; Augustine, Chad

    2017-05-01

    Enhanced Geothermal Systems (EGS) could potentially use technological advancements in coupled implementation of horizontal drilling and multistage hydraulic fracturing techniques in tight oil and shale gas reservoirs along with improvements in reservoir simulation techniques to design and create EGS reservoirs. In this study, a commercial hydraulic fracture simulation package, Mangrove by Schlumberger, was used in an EGS model with largely distributed pre-existing natural fractures to model fracture propagation during the creation of a complex fracture network. The main goal of this study is to investigate optimum treatment parameters in creating multiple large, planar fractures to hydraulically connect a horizontal injection well and a horizontal production well that are 10,000 ft. deep and spaced 500 ft. apart from each other. A matrix of simulations for this study was carried out to determine the influence of reservoir and treatment parameters on preventing (or aiding) the creation of large planar fractures. The reservoir parameters investigated during the matrix simulations include the in-situ stress state and properties of the natural fracture set such as the primary and secondary fracture orientation, average fracture length, and average fracture spacing. The treatment parameters investigated during the simulations were fluid viscosity, proppant concentration, pump rate, and pump volume. A final simulation with optimized design parameters was performed. The optimized design simulation indicated that high fluid viscosity, high proppant concentration, large pump volume and pump rate tend to minimize the complexity of the created fracture network. Additionally, a reservoir with 'friendly' formation characteristics such as large stress anisotropy, natural fractures set parallel to the maximum horizontal principal stress (SHmax), and large natural fracture spacing also promote the creation of large planar fractures while minimizing fracture complexity.

  19. Thermal-Hydrologic-Mechanical Behavior of Single Fractures in EGS Reservoirs

    Science.gov (United States)

    Zyvoloski, G.; Kelkar, S.; Yoshioka, K.; Rapaka, S.

    2010-12-01

    Enhanced Geothermal Systems (EGS) rely on the creation a connected fracture system or the enhancement of existing (natural) fractures by hydraulic and chemical treatments. EGS studies at Fenton Hill (New Mexico, USA) and Hijiori (Japan) have revealed that only a limited number of fractures contribute to the effective heat transfer surface area. Thus, the economic viability of EGS depends strongly on the creation and spacing of single fractures in order to efficiently mine heat from given volume of rock. Though there are many similarities between EGS and natural geothermal reservoirs, a major difference between the reservoir types is the (typically) high pumping pressures and induced thermal stresses at the injection wells of an EGS reservoir. These factors can be responsible for fracture dilation/extension and thermal short circuiting and depend strongly on the surrounding state of stress in the reservoir and mechanical properties. We will present results from our study of the thermal-hydrologic-mechanical (THM) behavior of a single fracture in a realistic subsurface stress field. We will show that fracture orientation, the stress environment, fracture permeability structure, and the relationship between permeability changes in a fracture resulting from mechanical displacement are all important when designing and managing an EGS reservoir. Lastly, we present a sensitivity analysis of the important parameters that govern fracture behavior with respect to field measurements. Temperature in high permeability fracture in an EGS reservoir

  20. A survey of U.S. Fish and Wildlife Service employees regarding constraints to connecting children with nature-Summary report to respondents

    Science.gov (United States)

    Ratz, Joan M.; Schuster, Rudy M.

    2011-01-01

    This report provides a summary of responses to the questions included on a survey of U.S. Fish and Wildlife Service employees regarding constraints to connecting children with nature. The survey was sponsored by the Division of Education Outreach at the National Conservation Training Center and conducted by the U.S. Geological Survey. The data collection process started on February 25, 2010 and ended on March 9, 2010. The dataset includes the responses from 320 individuals from all regions in the Service. The adjusted response rate for the survey was 55 percent. In this report, we provide the summary results for the survey questions in the order in which the questions were asked. The questions addressed the following topics: relevance of certain outcomes to the aspect of the Service's mission that relates to connecting people with nature, perceived success at connecting children with nature, the extent to which ten constraints present problems in connecting children with nature, and attitudes about the importance of connecting children with nature. The text of comments provided by respondents to open-ended questions is provided. In-depth analyses will be reported in the completion report for this project.

  1. Predicting the natural state of fractured carbonate reservoirs: An Andector Field, West Texas test of a 3-D RTM simulator

    Energy Technology Data Exchange (ETDEWEB)

    Tuncay, K.; Romer, S.; Ortoleva, P. [Indiana Univ., Bloomington, IN (United States); Hoak, T. [Kestrel Geoscience, Littleton, CO (United States); Sundberg, K. [Phillips Petroleum Co., Bartlesville, OK (United States)

    1998-12-31

    The power of the reaction, transport, mechanical (RTM) modeling approach is that it directly uses the laws of geochemistry and geophysics to extrapolate fracture and other characteristics from the borehole or surface to the reservoir interior. The objectives of this facet of the project were to refine and test the viability of the basin/reservoir forward modeling approach to address fractured reservoir in E and P problems. The study attempts to resolve the following issues: role of fracturing and timing on present day location and characteristics; clarifying the roles and interplay of flexure dynamics, changing rock rheological properties, fluid pressuring and tectonic/thermal histories on present day reservoir location and characteristics; and test the integrated RTM modeling/geological data approach on a carbonate reservoir. Sedimentary, thermal and tectonic data from Andector Field, West Texas, were used as input to the RTM basin/reservoir simulator to predict its preproduction state. The results were compared with data from producing reservoirs to test the RTM modeling approach. The effects of production on the state of the field are discussed in a companion report. The authors draw the following conclusions: RTM modeling is an important new tool in fractured reservoir E and P analysis; the strong coupling of RTM processes and the geometric and tensorial complexity of fluid flow and stresses require the type of fully coupled, 3-D RTM model for fracture analysis as pioneered in this project; flexure analysis cannot predict key aspects of fractured reservoir location and characteristics; fracture history over the lifetime of a basin is required to understand the timing of petroleum expulsion and migration and the retention properties of putative reservoirs.

  2. Heavy-oil recovery in naturally fractured reservoirs with varying wettability by steam solvent co-injection

    Energy Technology Data Exchange (ETDEWEB)

    Al Bahlani, A. [Alberta Univ., Edmonton, AB (Canada); Babadagli, T. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[Alberta Univ., Edmonton, AB (Canada)

    2008-10-15

    Steam injection may not be an efficient oil recovery process in certain circumstances, such as in deep reservoirs, where steam injection may be ineffective because of hot-water flooding due to excessive heat loss. Steam injection may also be ineffective in oil-wet fractured carbonates, where steam channels through fracture zones without effectively sweeping the matrix oil. Steam flooding is one of the many solutions for heavy oil recovery in unconsolidated sandstones that is in commercial production. However, heavy-oil fractured carbonates are more challenging, where the recovery is generally limited only to matrix oil drainage gravity due to unfavorable wettability or thermal expansion if heat is introduced during the process. This paper proposed a new approach to improve steam/hot-water injection and efficiency for heavy-oil fractured carbonate reservoirs. The paper provided background information on oil recovery from fractured carbonates and provided a statement of the problem. Three phases were described, including steam/hot-waterflooding phase (spontaneous imbibition); miscible flooding phase (diffusion); and steam/hot-waterflooding phase (spontaneous imbibition or solvent retention). The paper also discussed core preparation and saturation procedures. It was concluded that efficient oil recovery is possible using alternate injection of steam/hot water and solvent. 43 refs., 1 tab., 13 figs.

  3. Naturally Connecting the World

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Opportunities for Sourcing and Collaboration with Cotton-Made Home Textiles During China International Trade Fair for Home Textiles and Accessories held in Shanghai 2010 (on Aug.25th,the second day of the

  4. Urban Environmental Excursions: Designing field trips to demonstrate sustainable connections between natural and engineered systems in urban environments

    Science.gov (United States)

    Lemke, L. D.

    2012-12-01

    Field trips are a proven and effective instructional tool to connect students with the world around them. In most communities, opportunities abound to allow students to make connections between concepts introduced in classroom or lab activities and the urban environment that surrounds them. Potential destinations include solid and liquid waste disposal sites, brownfield redevelopment sites, hazardous waste sites, industrial complexes, or sites with ongoing environmental restoration efforts. Each of these locations presents opportunities to explore sustainable aspects of anthropogenic activities in relation to the natural systems that they seek to modify or exploit. Early planning is essential, however, because it can sometimes take several months lead time to arrange for a large group tour of industrial or municipal sites. Several practices may be employed to design effective learning experiences for students when visiting such sites. These include: 1) choose local sites to keep trips relevant and practical; 2) balance sites of environmental concern with those where significant progress is being made in environmental restoration or stewardship; 3) connect sites with a pertinent theme (e.g., air quality, water quality, economic development, environmental justice, etc.); 4) develop a sense of location among student participants by providing a map showing the relationship between campus and the field sites; 5) prepare a guidebook containing one-page descriptions of each stop along with a list of questions to stimulate discussion and promote active engagement among all participants; 6) employ expert guides to maximize students' access to authoritative information; 7) tie each field experience to your curriculum; and 8) model active learning by asking genuine questions and engaging in open discussions with experts and student participants. In this presentation, urban field trip design will be illustrated with examples from trips run in conjunction with freshman

  5. Geomechanically Coupled Simulation of Flow in Fractured Reservoirs

    Science.gov (United States)

    Barton, C.; Moos, D.; Hartley, L.; Baxter, S.; Foulquier, L.; Holl, H.; Hogarth, R.

    2012-12-01

    Capturing the necessary and sufficient detail of reservoir hydraulics to accurately evaluate reservoir behavior remains a significant challenge to the exploitation and management of fracture-dominated geothermal reservoirs. In these low matrix permeability reservoirs, stimulation response is controlled largely by the properties of natural and induced fracture networks, which are in turn controlled by the in situ stresses, the fracture distribution and connectivity and the hydraulic behavior of the fractures. This complex interaction of fracture flow systems with the present-day stress field compounds the problem of developing an effective and efficient simulation to characterize, model and predict fractured reservoir performance. We discuss here a case study of the integration of geological, geophysical, geomechanical, and reservoir engineering data to characterize the in situ stresses, the natural fracture network and the controls on fracture permeability in geothermal reservoirs. A 3D geomechanical reservoir model includes constraints on stress magnitudes and orientations, and constraints on mechanical rock properties and the fractures themselves. Such a model is essential to understanding reservoir response to stimulation and production in low matrix permeability, fracture-dominated reservoirs. The geomechanical model for this study was developed using petrophysical, drilling, and wellbore image data along with direct well test measurements and was mapped to a 3D structural grid to facilitate coupled simulation of the fractured reservoir. Wellbore image and stimulation test data were used along with microseismic data acquired during the test to determine the reservoir fracture architecture and to provide control points for a realistic inter-connected discrete fracture network. As most fractures are stress-sensitive, their hydraulic conductivities will change with changes in bottomhole flowing and reservoir pressures, causing variations in production profiles

  6. High-frequency electromagnetic properties of soft magnetic Nd2Co17 micron flakes fractured along c crystal plane with natural resonance frequency exceeding 10 GHz

    Science.gov (United States)

    Zhang, Yongbo; Wang, Peng; Ma, Tianyong; Wang, Ying; Qiao, Liang; Wang, Tao

    2016-02-01

    Planar anisotropy Nd2Co17 flakes fractured along c crystal plane were fabricated by surfactant-assisted high-energy ball milling technique. The magnetic flakes have a diameter range of 5-20 μm and a typical thickness of approximately 120 nm. The frequency dependence of complex permeability of Nd2Co17 epoxy resin composite has been investigated in the frequency range of 0.1-18 GHz. The measurement results show that the natural resonance frequency reaches 12.5 GHz while the initial permeability survives up to 2.26. The superior high frequency properties come from the large out-of-plane anisotropy field and the flake structure fractured along the c crystal plane of Nd2Co17. The planar anisotropic Nd2Co17 flakes have significant potential applications in the high-frequency devices working in the frequency beyond 10 GHz.

  7. Modeling of temperature and turbidity in a natural lake and a reservoir connected by pumped-storage operations

    Science.gov (United States)

    Bonalumi, Matteo; Anselmetti, Flavio S.; Wüest, Alfred; Schmid, Martin

    2012-08-01

    Pumped-storage (PS) systems are used to store electric energy as potential energy for release during peak demand. We investigate the impacts of a planned 1000 MW PS scheme connecting Lago Bianco with Lago di Poschiavo (Switzerland) on temperature and particle mass concentration in both basins. The upper (turbid) basin is a reservoir receiving large amounts of fine particles from the partially glaciated watershed, while the lower basin is a much clearer natural lake. Stratification, temperature and particle concentrations in the two basins were simulated with and without PS for four different hydrological conditions and 27 years of meteorological forcing using the software CE-QUAL-W2. The simulations showed that the PS operations lead to an increase in temperature in both basins during most of the year. The increase is most pronounced (up to 4°C) in the upper hypolimnion of the natural lake toward the end of summer stratification and is partially due to frictional losses in the penstocks, pumps and turbines. The remainder of the warming is from intense coupling to the atmosphere while water resides in the shallower upper reservoir. These impacts are most pronounced during warm and dry years, when the upper reservoir is strongly heated and the effects are least concealed by floods. The exchange of water between the two basins relocates particles from the upper reservoir to the lower lake, where they accumulate during summer in the upper hypolimnion (10 to 20 mg L-1) but also to some extent decrease light availability in the trophic surface layer.

  8. Investigation of the mechanical properties and failure modes of hybrid natural fiber composites for potential bone fracture fixation plates.

    Science.gov (United States)

    Manteghi, Saeed; Mahboob, Zia; Fawaz, Zouheir; Bougherara, Habiba

    2017-01-01

    The purpose of this study is to investigate the mechanical feasibility of a hybrid Glass/Flax/Epoxy composite material for bone fracture fixation such as fracture plates. These hybrid composite plates have a sandwich structure in which the outer layers are made of Glass/Epoxy and the core from Flax/Epoxy. This configuration resulted in a unique structure compared to prior composites proposed for similar clinical applications. In order to evaluate the mechanical properties of this hybrid composite, uniaxial tension, compression, three-point bending and Rockwell Hardness tests were conducted. In addition, water absorption tests were performed to investigate the rate of water absorption for the specimens. This study confirms that the proposed hybrid composite plates are significantly more flexible axially compared to conventional metallic plates. Furthermore, they have considerably higher ultimate strength in tension, compression and flexion. Such high strength will ensure good stability of bone-implant construct at the fracture site, immobilize adjacent bone fragments and carry clinical-type forces experienced during daily normal activities. Moreover, this sandwich structure with stronger and stiffer face sheets and more flexible core can result in a higher stiffness and strength in bending compared to tension and compression. These qualities make the proposed hybrid composite an ideal candidate for the design of an optimized fracture fixation system with much closer mechanical properties to human cortical bone.

  9. Simulation of Solute Flow and Transport in a Geostatistically Generated Fractured Porous System

    Science.gov (United States)

    Assteerawatt, A.; Helmig, R.; Haegland, H.; Bárdossy, A.

    2007-12-01

    Fractured aquifer systems have provided important natural resources such as petroleum, gas, water and geothermal energy and have also been recently under investigation for their suitability as storage sites for high-level nuclear waste. The resource exploitation and potential utilization have led to extensive studies aiming of understanding, characterizing and finally predicting the behavior of fractured aquifer systems. By applying a discrete model approach to study flow and transport processes, fractures are determined discretely and the effect of individual fractures can be explicitly investigated. The critical step for the discrete model is the generation of a representative fracture network since the development of flow paths within a fractured system strongly depends on its structure. The geostatistical fracture generation (GFG) developed in this study aims to create a representative fracture network, which combines the spatial structures and connectivity of a fracture network, and the statistical distribution of fracture geometries. The spatial characteristics are characterized from indicator fields, which are evaluated from fracture trace maps. A global optimization, Simulated annealing, is utilized as a generation technique and the spatial characteristics are formulated to its objective function. We apply the GFG to a case study at a Pliezhausen field block, which is a sandstone of a high fracture density. The generated fracture network from the GFG are compared with the statistically generated fracture network in term of structure and hydraulic behavior. As the GFG is based on a stochastic concept, several realizations of the same descriptions can be generated, hence, an overall behavior of the fracture-matrix system have to be investigated from various realizations which leads to a problem of computational demand. In order to overcome this problem, a streamline method for a solute transport in a fracture porous system is presented. The results obtained

  10. Numerical Investigation into the Influence of Bedding Plane on Hydraulic Fracture Network Propagation in Shale Formations

    Science.gov (United States)

    Yushi, Zou; Xinfang, Ma; Shicheng, Zhang; Tong, Zhou; Han, Li

    2016-09-01

    Shale formations are often characterized by low matrix permeability and contain numerous bedding planes (BPs) and natural fractures (NFs). Massive hydraulic fracturing is an important technology for the economic development of shale formations in which a large-scale hydraulic fracture network (HFN) is generated for hydrocarbon flow. In this study, HFN propagation is numerically investigated in a horizontally layered and naturally fractured shale formation by using a newly developed complex fracturing model based on the 3D discrete element method. In this model, a succession of continuous horizontal BP interfaces and vertical NFs is explicitly represented and a shale matrix block is considered impermeable, transversely isotropic, and linearly elastic. A series of simulations is performed to illustrate the influence of anisotropy, associated with the presence of BPs, on the HFN propagation geometry in shale formations. Modeling results reveal that the presence of BP interfaces increases the injection pressure during fracturing. HF deflection into a BP interface tends to occur under high strength and elastic anisotropy as well as in low vertical stress anisotropy conditions, which generate a T-shaped or horizontal fracture. Opened BP interfaces may limit the growth of the fracture upward and downward, resulting in a very low stimulated thickness. However, the opened BP interfaces favor fracture complexity because of the improved connection between HFs and NFs horizontally under moderate vertical stress anisotropy. This study may help predict the HF growth geometry and optimize the fracturing treatment designs in shale formations with complex depositional heterogeneity.

  11. Fracture Propagation and Permeability Change under Poro-thermoelastic Loads & Silica Reactivity in Enhanced Geothermal Systems

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad Ghassemi

    2009-10-01

    Geothermal energy is recovered by circulating water through heat exchange areas within a hot rock mass. Geothermal reservoir rock masses generally consist of igneous and metamorphic rocks that have low matrix permeability. Therefore, cracks and fractures play a significant role in extraction of geothermal energy by providing the major pathways for fluid flow and heat exchange. Therefore, knowledge of the conditions leading to formation of fractures and fracture networks is of paramount importance. Furthermore, in the absence of natural fractures or adequate connectivity, artificial fractures are created in the reservoir using hydraulic fracturing. Multiple fractures are preferred because of the large size necessary when using only a single fracture. Although the basic idea is rather simple, hydraulic fracturing is a complex process involving interactions of high pressure fluid injections with a stressed hot rock mass, mechanical interaction of induced fractures with existing natural fractures, and the spatial and temporal variations of in-situ stress. As a result, it is necessary to develop tools that can be used to study these interactions as an integral part of a comprehensive approach to geothermal reservoir development, particularly enhanced geothermal systems. In response to this need we have developed advanced poro-thermo-chemo-mechanical fracture models for rock fracture research in support of EGS design. The fracture propagation models are based on a regular displacement discontinuity formulation. The fracture propagation studies include modeling interaction of induced fractures. In addition to the fracture propagation studies, two-dimensional solution algorithms have been developed and used to estimate the impact of pro-thermo-chemical processes on fracture permeability and reservoir pressure. Fracture permeability variation is studied using a coupled thermo-chemical model with quartz reaction kinetics. The model is applied to study quartz precipitation

  12. Understanding Flow in Unconventional Reservoirs Fractures: Influence of Compaction and Cementation

    Science.gov (United States)

    Tokan-Lawal, A.; Prodanovic, M.; Landry, C. J.; Eichhubl, P.

    2014-12-01

    Natural fractures provide fluid flow pathways in otherwise low permeability reservoirs. These fractures are usually lined or completely filled with mineral cements. The presence of these cements causes very rough fracture walls that can constrict flow and hinder the connectivity between the fracture and matrix/fracture pores thereby reducing porosity and permeability. In order to accurately predict fluid transport in unconventional reservoirs, we study the influence of diagenesis, numerical cement and fracture roughness on flow in three different fractures: a carbonate outcrop from the Niobrara formation; and two distinct sandstones, from a core from the Travis Peak and an outcrop from the Torridonian. We use x-ray microtomography imaging to provide information on fracture geometry. Image analysis and characterization of the connectivity and geometric tortuosity of the pore space and individual fluid phases at different saturations, is performed via ImageJ and 3DMA Rock software. We also use a combination of the level-set-method-based progressive-quasistatic algorithm (LSMPQS software), and lattice Boltzmann simulation (Palabos software) to characterize the capillary dominated displacement properties, absolute permeability and relative permeability of the naturally cemented fractures within. In addition, we numerically investigate the effect of (uniform) cementation on the fracture permeability as well as the tortuosity of the pore space and the capillary pressure-water saturation (Pc-Sw) relationship in the Niobrara. Finally, we create 3D prints of the fractures for visualization purposes. Permeability estimates in the studied fractures vary by several orders of magnitude when computed with the different correlations that currently exist in the literature. The presence of cements increases the geometric tortuosity of the pore space and capillary pressure while reducing the permeability. Contrary to our expectation, the tortuosity of the wetting and non

  13. Tectonic Setting and Characteristics of Natural Fractures in MesaVerde and Dakota Reservoirs of the San Juan Basin

    Energy Technology Data Exchange (ETDEWEB)

    LORENZ,JOHN C.; COOPER,SCOTT P.

    2000-12-20

    The Cretaceous strata that fill the San Juan Basin of northwestern New Mexico and southwestern Colorado were shortened in a generally N-S to NN13-SSW direction during the Laramide orogeny. This shortening was the result of compression of the strata between southward indentation of the San Juan Uplift at the north edge of the basin and northward to northeastward indentation of the Zuni Uplift from the south. Right-lateral strike-slip motion was concentrated at the eastern and western basin margins of the basin to form the Hogback Monocline and the Nacimiento Uplift at the same time, and small amounts of shear may have been pervasive within the basin as well. Vertical extension fractures, striking N-S to NNE-SSW with local variations (parallel to the Laramide maximum horizontal compressive stress), formed in both Mesaverde and Dakota sandstones under this system, and are found in outcrops and in the subsurface of the San Juan Basin. The immature Mesaverde sandstones typically contain relatively long, irregular, vertical extension fractures, whereas the quartzitic Dakota sandstones contain more numerous, shorter, sub-parallel, closely spaced, extension fractures. Conjugate shear planes in several orientations are also present locally in the Dakota strata.

  14. 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

  15. 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

  16. Gendered Connections

    DEFF Research Database (Denmark)

    Jensen, Steffen Bo

    2009-01-01

    This article explores the gendered nature of urban politics in Cape Town by focusing on a group of female, township politicians. Employing the Deleuzian concept of `wild connectivity', it argues that these politically entrepreneurial women were able to negotiate a highly volatile urban landscape...... space also drew on quite traditional notions of female respectability. Furthermore, the article argues, the form of wild connectivity to an extent was a function of the political transition, which destabilized formal structures of gendered authority. It remains a question whether this form...... of connectivity might endure, as Capetonian politics assumes a post-apartheid structure....

  17. 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)

  18. Microcracks and Overpressure- Induced Fractures

    Institute of Scientific and Technical Information of China (English)

    Ahmed M. Al - QAHTANI

    2001-01-01

    The microfractures and natural fractures studies have a great significance in the hydrocarbon accumulation exploration and can be a good supporter for wide geophysical study on the major structures. This paper is a brief review on microcracks and overpressure- induced fracture. It is to discuss different views on the mechanism of fractures in the subsurface of the earth.

  19. Hip Fracture

    Science.gov (United States)

    Diseases and Conditions Hip fracture By Mayo Clinic Staff A hip fracture is a serious injury, with complications that can be life-threatening. The risk of hip fracture rises with age. Older people are at a ...

  20. Numerical analysis of fracture propagation during hydraulic fracturing operations in shale gas systems

    Science.gov (United States)

    Researchers used the TOUGH+ geomechanics computational software and simulation system to examine the likelihood of hydraulic fracture propagation (the spread of fractures) traveling long distances to connect with drinking water aquifers.

  1. Detection of water contamination from hydraulic fracturing wastewater: a μPAD for bromide analysis in natural waters.

    Science.gov (United States)

    Loh, Leslie J; Bandara, Gayan C; Weber, Genevieve L; Remcho, Vincent T

    2015-08-21

    Due to the rapid expansion in hydraulic fracturing (fracking), there is a need for robust, portable and specific water analysis techniques. Early detection of contamination is crucial for the prevention of lasting environmental damage. Bromide can potentially function as an early indicator of water contamination by fracking waste, because there is a high concentration of bromide ions in fracking wastewaters. To facilitate this, a microfluidic paper-based analytical device (μPAD) has been developed and optimized for the quantitative colorimetric detection of bromide in water using a smartphone. A paper microfluidic platform offers the advantages of inexpensive fabrication, elimination of unstable wet reagents, portability and high adaptability for widespread distribution. These features make this assay an attractive option for a new field test for on-site determination of bromide.

  2. Effect of natural aging on the microstructural regions, mechanical properties, corrosion resistance and fracture in welded joints on API5L X52 steel pipeline

    Energy Technology Data Exchange (ETDEWEB)

    Vargas-Arista, B.; Albiter, A.; Garcia-Vazquez, F.; Mendoza-Camargo, O.; Hallen, J. M.

    2014-07-01

    A characterization study was done to analyze how microstructural regions affect the mechanical properties, corrosion and fractography of the Heat Affected Zone (HAZ), weld bead and base metal for pipe naturally aged for 21 years at 30 degree centigrade. Results showed that microstructures exhibited damage and consequently decrease in properties, resulting in over-aged due to service. SEM analysis showed that base metal presented coarse ferrite grain. Tensile test indicated that microstructures showed discontinuous yield. Higher tensile strength was obtained for weld bead, which exhibited a lower impact energy in comparison to that of HAZ and base metal associated with brittle fracture by trans-granular cleavage. The degradation of properties was associated with the coarsening of nano-carbides observed through TEM images analysis, which was confirmed by SEM fractography of tensile and impact fracture surfaces. The weld bead reached the largest void density and highest susceptibility to corrosion in H{sub 2}S media when compared to those of the HAZ and base metal. (Author)

  3. Oh, Deer!: Predator and Prey Relationships--Students Make Natural Connections through the Integration of Mathematics and Science

    Science.gov (United States)

    Reeder, Stacy; Moseley, Christine

    2006-01-01

    This article describes an activity that integrates both mathematics and science while inviting students to make connections between the two and learn significant concepts in a meaningful way. Students work within the real-world context of wildlife population scenarios to make predictions, test their hypotheses, and determine and construct graphs…

  4. Advanced reservoir characterization and evaluation of CO{sub 2} gravity drainage in the naturally fractured Spraberry Trend Area, Class III

    Energy Technology Data Exchange (ETDEWEB)

    Heckman, Tracy; Schechter, David S.

    2000-04-11

    The overall goal of this project was to assess the economic feasibility of CO{sub 2} flooding the naturally fractured Spraberry Trend Area in West Texas. This objective was accomplished by conducting research in four areas: (1) extensive characterization of the reservoirs, (2) experimental studies of crude oil/brine/rock (COBR) interaction in the reservoirs, (3) analytical and numerical simulation of Spraberry reservoirs, and, (4) experimental investigations on CO{sub 2} gravity drainage in Spraberry whole cores. This report provides results of the fourth year of the five-year project for each of the four areas including a status report of field activities leading up to injection of CO{sub 2}.

  5. Determination and maintenance of DE minimis risk for migration of residual tritium (3H) from the 1969 Project Rulison nuclear test to nearby hydraulically fractured natural gas wells.

    Science.gov (United States)

    Daniels, Jeffrey I; Chapman, Jenny B

    2013-05-01

    The Project Rulison underground nuclear test was a proof-of-concept experiment that was conducted under the Plowshare Program in 1969 in the Williams Fork Formation of the Piceance Basin in west-central Colorado. Today, commercial production of natural gas is possible from low permeability, natural gas bearing formations like that of the Williams Fork Formation using modern hydraulic fracturing techniques. With natural gas exploration and production active in the Project Rulison area, this human health risk assessment was performed in order to add a human health perspective for site stewardship. Tritium (H) is the radionuclide of concern with respect to potential induced migration from the test cavity leading to subsequent exposure during gas-flaring activities. This analysis assumes gas flaring would occur for up to 30 d and produce atmospheric H activity concentrations either as low as 2.2 × 10 Bq m (6 × 10 pCi m) from the minimum detectable activity concentration in produced water or as high as 20.7 Bq m (560 pCi m), which equals the highest atmospheric measurement reported during gas-flaring operations conducted at the time of Project Rulison. The lifetime morbidity (fatal and nonfatal) cancer risks calculated for adults (residents and workers) and children (residents) from inhalation and dermal exposures to such activity concentrations are all below 1 × 10 and considered de minimis. The implications for monitoring production water for conforming health-protective, risk-based action levels also are examined.

  6. Tectonic Setting and Characteristics of Natural Fractures in Mesaverde and Dakota Reservoirs of the San Juan Basin, New Mexico and Colorado

    Energy Technology Data Exchange (ETDEWEB)

    LORENZ, JOHN C.; COOPER, SCOTT P.

    2001-01-01

    A set of vertical extension fractures, striking N-S to NNE-SSW but with local variations, is present in both the outcrop and subsurface in both Mesaverde and Dakota sandstones. Additional sets of conjugate shear fractures have been recognized in outcrops of Dakota strata and may be present in the subsurface. However, the deformation bands prevalent locally in outcrops in parts of the basin as yet have no documented subsurface equivalent. The immature Mesaverde sandstones typically contain relatively long, irregular extension fractures, whereas the quartzitic Dakota sandstones contain short, sub-parallel, closely spaced, extension fractures, and locally conjugate shear planes as well. Outcrops typically display secondary cross fractures which are rare in the subsurface, although oblique fractures associated with local structures such as the Hogback monocline may be present in similar subsurface structures. Spacings of the bed-normal extension fractures are approximately equal to or less than the thicknesses of the beds in which they formed, in both outcrop and subsurface. Fracture intensities increase in association with faults, where there is a gradation from intense fracturing into fault breccia. Bioturbation and minimal cementation locally inhibited fracture development in both formations, and the vertical limits of fracture growth are typically at bedding/lithology contrasts. Fracture mineralizations have been largely dissolved or replaced in outcrops, but local examples of preserved mineralization show that the quartz and calcite common to subsurface fractures were originally present in outcrop fractures. North-south trending compressive stresses created by southward indentation of the San Juan dome area (where Precambrian rocks are exposed at an elevation of 14,000 ft) and northward indentation of the Zuni uplift, controlled Laramide-age fracturing. Contemporaneous right-lateral transpressive wrench motion due to northeastward translation of the basin was both

  7. Refugia Research Coalition: A regional-scale approach for connecting refugia science to natural and cultural resource management

    Science.gov (United States)

    Background / question / methods Warmer air and water temperatures, changing precipitation patterns, and altered fire regimes associated with climate change threaten many important natural and cultural resources. Climate change refugia are areas relatively buffered from contempora...

  8. Heat-pulse flowmeter test to characterize the seawater intrusion in fractured rock, western coast of Korea

    Science.gov (United States)

    Oh, H.; Hwang, S.; Shin, J.; Park, K.

    2007-12-01

    Seawater intrusion occurs commonly along the western and southern coasts of Korea. Almost coastal area consists of a reclaimed land, and is affected by seawater intrusion through the fractured rocks connected the seaside within several kilometers of coasts. A combination of drilling, conventional geophysical well logging including caliper log, natural gamma log, fluid temperature/conductivity log etc., acoustic televiewer, flowmeter, hydrophysical logging, packer test, and freshwater injection test was performed to evaluate seawater intrusion through the fractured rock in Baeksu-eup, Youngkwang-gun, Korea. The geological structure of the survey area comprises mud, sand, and granite and andesite bedrock (below an approximate depth of 22 m). The test boreholes are located with the brackish area interpreted with surface geophysical survey and hydrogeochemcial survey. The depth of two test boreholes is 50m, and the diameter is 3 inch, the distance between boreholes is 10m. Although the core log showed the several fractures, we didn't identify the minor fractures using 3-arm caliper logs because of small aperture size of fractures. The electrical conductivity of the borehole fluid is seen to be more than 1000 μS/cm at depth of about 35 m, and the highest conductivity is about 5000 μS/cm. Several intervals shown the change of conductivity logs doesn't relate with fractures identified by 3-arm caliper logs. In order to verify the permeable fractures, heat-pulse flowmeter test was conducted within single hole and interpreted with Paillet inversion method. Five permeable fractures are detected and hydraulic properties are estimated. These results are compared with hydrophysical logging performed one borehole. After the replacement of borehole fluid with freshwater, the change of fluid conductivity shows at least seven fractures with different salinity. Main fractures with highest salinity detected acoustic televiewer show low dip angles. To define subsurface connection

  9. Habit as a Connection Between Nature, Mind and Culture in C.S. Peirce’s Semiotic Pragmaticism

    DEFF Research Database (Denmark)

    Brier, Søren

    theories and models. The end of research in a certified truth is an ideal far away in the future. Furthermore he was not a physicalistic material mechanists but a process philosopher and an evolutionary synechist. This means that he thought that mind and matter was connected in a continuum and that matter......’s theory of motion was reversible. Time had no arrow. But in Peirce’s cosmogony change is at the basis as Firstness is imbued with the tendency to take habits and time therefore has an arrow and is irreversible and therefore what the laws manifested as the universe develop. This was unthinkable from...

  10. A natural fiber composite in a pelagic limestone-chert sequence. The importance of mechanical stratigraphy for fracture type development in carbonate anticlines.

    Science.gov (United States)

    Petracchini, Lorenzo; Antonellini, Marco; Scrocca, Davide; Billi, Andrea

    2013-04-01

    Thrust fault-related folds in carbonate rocks are characterized by deformation accommodated by different kinds of structures, such as joints, faults, pressure solution seams (PSSs), and deformation bands, which may form at various stages during the folding process. Defining the distribution, orientation, and the type of fold-related structures and understanding the relationships between folding and fracturing is significant both for theoretical and practical purposes. Furthermore, as the deformation related to the folding process influences fluid flow through rocks, identifying the types of structures formed during folding is as important as predicting their geometries. To unravel the relationship between mechanical stratigraphy and folding process, the well-exposed Cingoli anticline (Northern Apennines), has been studied in detail. The Upper Cretaceous-Middle Eocene stratigraphy of the Cingoli anticline is characterized by a pelagic multilayer made up of fine-grained pelagic limestones and, marly limestones, in places alternated with thin continuous chert layers. The presence of several outcrops located in different structural positions of the anticline makes the Cingoli anticline an excellent natural laboratory to investigate relationships between folding, fracturing, and mechanical stratigraphy relative to the structural setting of the fold. The field data collected show that high angle to bedding PSSs, which formed before tilting and during the first stage of folding, are not homogeneously distributed in the pelagic limestones. Generally, high angle to bedding PSSs form in the marly pelagic limestones and they have been observed in several outcrops and in different structural positions except where the marly limestones are inter-bedded with stiffer chert layers. In order to analyse theoretically what observed in the field, we compared the deformation of limestones and chert layers with the deformation acting on fiber composites. In the mechanics of materials

  11. A 3-Dimensional discrete fracture network generator to examine fracture-matrix interaction using TOUGH2

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Kazumasa; Yongkoo, Seol

    2003-04-09

    Water fluxes in unsaturated, fractured rock involve the physical processes occurring at fracture-matrix interfaces within fracture networks. Modeling these water fluxes using a discrete fracture network model is a complicated effort. Existing preprocessors for TOUGH2 are not suitable to generate grids for fracture networks with various orientations and inclinations. There are several 3-D discrete-fracture-network simulators for flow and transport, but most of them do not capture fracture-matrix interaction. We have developed a new 3-D discrete-fracture-network mesh generator, FRACMESH, to provide TOUGH2 with information about the fracture network configuration and fracture-matrix interactions. FRACMESH transforms a discrete fracture network into a 3 dimensional uniform mesh, in which fractures are considered as elements with unique rock material properties and connected to surrounding matrix elements. Using FRACMESH, individual fractures may have uniform or random aperture distributions to consider heterogeneity. Fracture element volumes and interfacial areas are calculated from fracture geometry within individual elements. By using FRACMESH and TOUGH2, fractures with various inclinations and orientations, and fracture-matrix interaction, can be incorporated. In this paper, results of flow and transport simulations in a fractured rock block utilizing FRACMESH are presented.

  12. Existence of a natural instability not predicted by theory and connected to a wall deformation in a laminar boundary layer

    Science.gov (United States)

    Gougat, P.; Martin, F.

    1981-01-01

    Natural instability related to negative wall deformation was studied. It was shown that natural instabilities which propagate in a laminar boundary layer of a flat plate are in agreement with stability theory. It is found that if a wall has a deformation, a second frequency does exist, which is not predicted and is twice the first frequency. This second instable frequency only appears if there is a negative velocity gradient. The phenomenon is located very closely to the wall and drops off rapidly when moved away from it.

  13. [Atlas fractures].

    Science.gov (United States)

    Schären, S; Jeanneret, B

    1999-05-01

    Fractures of the atlas account for 1-2% of all vertebral fractures. We divide atlas fractures into 5 groups: isolated fractures of the anterior arch of the atlas, isolated fractures of the posterior arch, combined fractures of the anterior and posterior arch (so-called Jefferson fractures), isolated fractures of the lateral mass and fractures of the transverse process. Isolated fractures of the anterior or posterior arch are benign and are treated conservatively with a soft collar until the neck pain has disappeared. Jefferson fractures are divided into stable and unstable fracture depending on the integrity of the transverse ligament. Stable Jefferson fractures are treated conservatively with good outcome while unstable Jefferson fractures are probably best treated operatively with a posterior atlanto-axial or occipito-axial stabilization and fusion. The authors preferred treatment modality is the immediate open reduction of the dislocated lateral masses combined with a stabilization in the reduced position using a transarticular screw fixation C1/C2 according to Magerl. This has the advantage of saving the atlanto-occipital joints and offering an immediate stability which makes immobilization in an halo or Minerva cast superfluous. In late instabilities C1/2 with incongruency of the lateral masses occurring after primary conservative treatment, an occipito-cervical fusion is indicated. Isolated fractures of the lateral masses are very rare and may, if the lateral mass is totally destroyed, be a reason for an occipito-cervical fusion. Fractures of the transverse processes may be the cause for a thrombosis of the vertebral artery. No treatment is necessary for the fracture itself.

  14. Explaining Emotional Attachment to a Protected Area by Visitors' Perceived Importance of Seeing Wildlife, Behavioral Connections with Nature and Sociodemographics

    NARCIS (Netherlands)

    Huigen, Paulus P.P.; Haartsen, Tialda; Folmer, Akke

    2013-01-01

    Recently, the interest in understanding emotional bonds with protected nature areas has been growing. The role of wildlife in emotional bonds with places has until now not been the focus of many studies. The aim of our paper is to explore relations between the perceived importance of seeing wildlife

  15. Legal and regulatory possibility of connection between interstate natural gas distribution networks instead of constructing transport pipelines; Possibilidade juridoco-regulatoria da conexao interestadual entre redes de distribuicao de gas natural como alternativa a construcao de gasodutos de transporte

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Gustavo Mano [Andrade, Mano - Advogados, Rio de Janeiro, RJ (Brazil)

    2012-07-01

    According to Revista Brasil Energia (2011a), the local natural gas distribution concessionaire in the State of Sao Paulo Gas Brasiliano Distribuidora - GBD, plans to expand its distribution pipeline network in western Sao Paulo up to the border of the State of Minas Gerais, near the region known as Minas Triangle where a connection with the pipeline network of the State of Minas Gerais' natural gas distribution company, Companhia de Gas de Minas Gerais - GASMIG shall be built in order to supply natural gas to an ammonia plant to be built by PETROBRAS in the City of Uberaba. Still according to the publication, the project described above would be an alternative to the construction of a transportation pipeline that, since the enforcement of the Gas Law - Law No. 11.909/09 (Brasil, 2009), should be subject to concession contracts preceded by a complex, and probably delayed, planning and procurement. However, there is a transportation pipeline project, deriving from the Bolivia-Brazil transportation pipeline near the city of Sao Carlos, in Sao Paulo, crossing the Minas Triangle and finishing in the State of Goias. This project is owned by TGBC Company. The existence of two gas pipeline projects with very similar paths to supply virtually the same regions and based on different regulatory frameworks, one consisting of a connection between the distribution networks of different States and another based on the concept of pipeline transportation of gas under the legal and regulatory federal jurisdiction raises the discussion about the possibility of legal and regulatory interstate connections of distribution pipeline networks as an alternative to planning, allocation and construction of a transportation pipelines. This article aims to examine the legal and regulatory foundations of both alternatives and delineate the limits of performance of States and Federal Government on legislation and regulation concerning the movement of natural gas pipeline through the Country

  16. The Functional Potential of Microbial Communities in Hydraulic Fracturing Source Water and Produced Water from Natural Gas Extraction Characterized by Metagenomic Sequencing

    OpenAIRE

    Arvind Murali Mohan; Bibby, Kyle J.; Daniel Lipus; Hammack, Richard W.; Gregory, Kelvin B

    2014-01-01

    Microbial activity in produced water from hydraulic fracturing operations can lead to undesired environmental impacts and increase gas production costs. However, the metabolic profile of these microbial communities is not well understood. Here, for the first time, we present results from a shotgun metagenome of microbial communities in both hydraulic fracturing source water and wastewater produced by hydraulic fracturing. Taxonomic analyses showed an increase in anaerobic/facultative anaerobi...

  17. Root fractures

    DEFF Research Database (Denmark)

    Andreasen, Jens Ove; Christensen, Søren Steno Ahrensburg; Tsilingaridis, Georgios

    2012-01-01

    The purpose of this study was to analyze tooth loss after root fractures and to assess the influence of the type of healing and the location of the root fracture. Furthermore, the actual cause of tooth loss was analyzed.......The purpose of this study was to analyze tooth loss after root fractures and to assess the influence of the type of healing and the location of the root fracture. Furthermore, the actual cause of tooth loss was analyzed....

  18. Stress Fractures

    Science.gov (United States)

    Stress fractures Overview Stress fractures are tiny cracks in a bone. They're caused by repetitive force, often from overuse — such as repeatedly jumping up and down or running long distances. Stress fractures can also arise from normal use of ...

  19. Fracture Networks in Sea Ice

    Directory of Open Access Journals (Sweden)

    Jonas Nesland Vevatne

    2014-04-01

    Full Text Available Fracturing and refreezing of sea ice in the Kara sea are investigated using complex networkanalysis. By going to the dual network, where the fractures are nodes and their intersectionslinks, we gain access to topological features which are easy to measure and hence comparewith modeled networks. Resulting network reveal statistical properties of the fracturing process.The dual networks have a broad degree distribution, with a scale-free tail, high clusteringand efficiency. The degree-degree correlation profile shows disassortative behavior, indicatingpreferential growth. This implies that long, dominating fractures appear earlier than shorterfractures, and that the short fractures which are created later tend to connect to the longfractures.The knowledge of the fracturing process is used to construct growing fracture network (GFNmodel which provides insight into the generation of fracture networks. The GFN model isprimarily based on the observation that fractures in sea ice are likely to end when hitting existingfractures. Based on an investigation of which fractures survive over time, a simple model forrefreezing is also added to the GFN model, and the model is analyzed and compared to the realnetworks.

  20. Planet Earth, Humans, Gravity and Their Connection to Natural Medicine-Essence from a 5000 Yrs Old Ancient Pedagogy

    Science.gov (United States)

    Lakshmanan, S.; Monsanto, C.; Radjendirane, B.

    2015-12-01

    According to the Ancient Indian Science, the fundamental constituents of planet earth are the five elements (Solid, Liquid, Heat, Air and Akash (subtlest energy field)). The same five elements constitute the human body. The Chinese and many other native traditions have used their deep understanding of these elements to live in balance with the planet. David Suzuki has elaborated on this key issue in his classic book, The Legacy: "Today we are in a state of crisis, and we must join together to respond to that crisis. If we do so, Suzuki envisions a future in which we understand that we are the Earth and live accordingly. All it takes is imagination and a determination to live within our, and the planet's, means". Gravity, the common force that connects both the body and earth plays a major role in the metabolism as well as the autonomous function of different organs in the body. Gravity has a direct influence on the fruits and vegetables that are grown on the planet as well. As a result, there is a direct relationship among gravity, food and human health. My talk will cover the missing link between the Earth's Gravity and the human health. A new set of ancient axioms will be used to address this and many other issues that are remain as "major unsolved problems" linking modern Geophysical and Health sciences.

  1. Arabidopsis thaliana natural variation reveals connections between UV radiation stress and plant pathogen-like defense responses.

    Science.gov (United States)

    Piofczyk, Thomas; Jeena, Ganga; Pecinka, Ales

    2015-08-01

    UV radiation is a ubiquitous component of solar radiation that affects plant growth and development. Here we studied growth related traits of 345 Arabidopsis thaliana accessions in response to UV radiation stress. We analyzed the genetic basis of this natural variation by genome-wide association studies, which suggested a specific candidate genomic region. RNA-sequencing of three sensitive and three resistant accessions combined with mutant analysis revealed five large effect genes. Mutations in PHE ammonia lyase 1 (PAL1) and putative kinase At1g76360 rendered Arabidopsis hypersensitive to UV stress, while loss of function from putative methyltransferase At4g22530, novel plant snare 12 (NPSN12) and defense gene activated disease resistance 2 (ADR2) conferred higher UV stress resistance. Three sensitive accessions showed strong ADR2 transcriptional activation, accumulation of salicylic acid (SA) and dwarf growth upon UV stress, while these phenotypes were much less affected in resistant plants. The phenotype of sensitive accessions resembles autoimmune reactions due to overexpression of defense related genes, and suggests that natural variation in response to UV radiation stress is driven by pathogen-like responses in Arabidopsis.

  2. 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

  3. Upscaling of the specific surface area for reactive transport modelling in fractured rock

    Science.gov (United States)

    Cvetkovic, Vladimir

    2014-05-01

    The impact of flow heterogeneity on chemical transport from single to multiple fractures, is investigated. The emphasis is on the dynamic nature of the specific surface area (SSA) due to heterogeneity of the flow, relative to a purely geometrical definition. It is shown how to account for SSA as a random variable in modelling multi-component reactions. The flow-dependent SSA is interpreted probabilistically, following inert tracer particles along individual fractures. Upscaling to a fracture network is proposed as a time-domain random walk based on the statistics of SSA for single fractures. Statistics of SSA are investigated for three correlation structures of transmissivity, one classical multi-gaussian, and two non-Gaussian. The coefficient of variation of single fracture SSA decreases monotonously with the distance over the fracture length; the CV of the upscaled SSA reduces further such that after ca 20 fractures it is under 0.1 for a disconnected field, and around 0.2 for connected and multi-gaussian fields. This implies that after 10-20 fractures, uncertainty in SSA is significantly reduced, justifying the use of an effective value. A conservative, lower bound for the dimensionless upscaled effective SSA was found to be 1, suitable for all heterogeneity structures, assuming the cubic hydraulic law applicable.

  4. Advanced reservoir characterization and evaluation of CO{sub 2} gravity drainage in the naturally fractured Spraberry Trend Area. Annual report, September 1, 1996--August 31, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Schechter, D.S.

    1998-07-01

    The overall goal of this project is to assess the economic feasibility of CO{sub 2} flooding the naturally fractured Spraberry Trend Area in West Texas. This objective is being accomplished by conducting research in four areas: (1) extensive characterization of the reservoirs, (2) experimental studies of crude oil/brine/rock (COBR) interaction in the reservoirs, (3) reservoir performance analysis, and (4) experimental investigations on CO{sub 2} gravity drainage in Spraberry whole cores. This report provides results of the second year of the five-year project for each of the four areas. In the first area, the author has completed the reservoir characterization, which includes matrix description and detection (from core-log integration) and fracture characterization. This information is found in Section 1. In the second area, the author has completed extensive inhibition experiments that strongly indicate that the weakly water-wet behavior of the reservoir rock may be responsible for poor waterflood response observed in many Spraberry fields. In the third area, the author has made significant progress in analytical and numerical simulation of performance in Spraberry reservoirs as seen in Section 3. In the fourth area, the author has completed several suites of CO{sub 2} gravity drainage in Spraberry and Berea whole cores at reservoir conditions and reported in Section 4. The results of these experiments have been useful in developing a model for free-fall gravity drainage and have validated the premise that CO{sub 2} will recover oil from tight, unconfined Spraberry matrix. The final three years of this project involves implementation of the CO{sub 2} pilot. Up to twelve new wells are planned in the pilot area; water injection wells to contain the CO{sub 2}, three production wells to monitor performance of CO{sub 2}, CO{sub 2} injection wells including one horizontal injection well and logging observation wells to monitor CO{sub 2} flood fronts. Results of drilling

  5. Effect of natural aging on the microstructural regions, mechanical properties, corrosion resistance and fracture in welded joints on API5L X52 steel pipeline

    Directory of Open Access Journals (Sweden)

    Vargas-Arista, Benjamín

    2014-09-01

    Full Text Available A characterization study was done to analyze how microstructural regions affect the mechanical properties, corrosion and fractography of the Heat Affected Zone (HAZ, weld bead and base metal for pipe naturally aged for 21 years at 30 °C. Results showed that microstructures exhibited damage and consequently decrease in properties, resulting in over-aged due to service. SEM analysis showed that base metal presented coarse ferrite grain. Tensile test indicated that microstructures showed discontinuous yield. Higher tensile strength was obtained for weld bead, which exhibited a lower impact energy in comparison to that of HAZ and base metal associated with brittle fracture by trans-granular cleavage. The degradation of properties was associated with the coarsening of nano-carbides observed through TEM images analysis, which was confirmed by SEM fractography of tensile and impact fracture surfaces. The weld bead reached the largest void density and highest susceptibility to corrosion in H2S media when compared to those of the HAZ and base metal.Se realizó un estudio de caracterización para analizar cómo la microestructura afecta a las propiedades mecánicas, corrosión y fractura de la zona afectada por calor (ZAC, soldadura y metal base para tubería envejecida naturalmente durante 21 años a 30 °C. Los resultados indicaron que las microestructuras presentaron daño y consecuentemente reducción en propiedades mecánicas, como consecuencia del envejecimiento por servicio. El estudio mediante MEB mostró que el metal base presenta grano ferrítico grueso. La prueba de tensión indicó que las microestructuras mostraron fluencia discontinua. La mayor resistencia a la tracción se presentó en la soldadura, la cual alcanzó menor energía de impacto en comparación con la ZAC y metal base asociado con fractura frágil por clivaje transgranular. La degradación de las propriedades está en relación con el engrosamiento de nanocarburos observados a

  6. Geothermal Ultrasonic Fracture Imager

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, Doug [Baker-Hughes Oilfield Operation Inc., Houston, TX (United States); Leggett, Jim [Baker-Hughes Oilfield Operation Inc., Houston, TX (United States)

    2013-07-29

    The Geothermal Ultrasonic Fracture Imager project has a goal to develop a wireline ultrasonic imager that is capable of operating in temperatures up to 300°C (572°F) and depths up to 10 km (32,808 ft). This will address one of the critical needs in any EGS development of understanding the hydraulic flow paths in the reservoir. The ultrasonic imaging is well known in the oil and gas industry as one of the best methods for fracture evaluation; providing both high resolution and complete azimuthal coverage of the borehole. This enables fracture detection and characterization, both natural and induced, providing information as to their location, dip direction and dip magnitude. All of these factors are critical to fully understand the fracture system to enable the optimization of the thermal drainage through injectors and producers in a geothermal resource.

  7. The Use of Hydraulic Head and Atmospheric Tritium to Identify Presence of Fractures in Clayey Aquitards: Numerical Analysis

    Science.gov (United States)

    Farah, E. A.; Parker, B. L.; Cherry, J. A.

    2003-12-01

    Surficial clayey aquitards can provide underlying aquifers with strong protection from contamination if vertically connected open fractures are absent. Hence, methods are needed to identify such contaminant pathways. An existing two-dimensional model for steady-state groundwater flow and solute transport (FRACTRAN) was used for cross-sectional simulations to assess the prospects for using field measurements of hydraulic head and atmospheric (i.e. bomb) tritium in surficial aquitards to determine presence and nature of hydraulically connected fractures. Simulations for a 15-m thick horizontal aquitard, with shallow water table and downward groundwater flow, show that field measurements of head and tritium at points appropriately spaced along a horizontal line at the lower part of the aquitard provide unique insight since they offer the highest chance for detecting vertical fractures. Simulations represented sets of predominant vertical and horizontal fractures of uniform aperture (25 æm) and variable length. The simulations focused on fracture-network features assigned based on the literature of field investigations. The horizontal profiles show peaks and troughs for head, and always peaks for tritium concentrations at fracture localities. Use of only head or tritium alone may locate fractures, but may not discover whether each fracture is connected to the ground surface or aquifer top, or both. On the other hand, the coupled patterns of head and tritium can be used to identify fractures more accurately. For example, a head trough and a tritium sharp peak represent a fully penetrating fracture, while a head peak and a rounded-tip tritium peak represent a partially penetrating fracture. Moreover, these two are easily differentiated from an embedded fracture that is represented by a relatively small head trough and a short sharp tritium peak. The method of monitoring along a horizontal line was applied to the conceptual 15-m thick aquitard imitating horizontal

  8. Remote Sensing of Subsurface Fractures in the Otway Basin, South Australia

    Science.gov (United States)

    Bailey, Adam; King, Rosalind; Holford, Simon; Hand, Martin

    2013-04-01

    conductive fractures are optimally oriented for reactivation in the present-day strike-slip fault regime, and so are likely to be open to fluid flow. To gain an understanding of the broader extent of these natural fractures, it is necessary to analyse more regional 3D seismic data. It is well documented that fault and fracture networks like those generally observed in image logs lie well below seismic amplitude resolution, making them difficult to observe directly on amplitude data. However, seismic attributes can be calculated to provide some information on sub-seismic scale structural and stratigraphic features. Using the merged Balnaves/Haselgrove 3D seismic cube acquired over the Penola Trough, attribute maps of complex multi-trace dip-steered coherency and most positive curvature, among others, were used to document the presence of discontinuities within the seismic data which area likely to represent natural fractures, and to best constrain the likely extent of the fracture network which they form. The resulting fracture network model displays relatively good connectivity surrounding structural features intersecting the studied horizons, although large areas lacking significant discontinuities are observed. These areas make it unlikely that the fracture network contributes to permeability on a basin-wide scale, though observed features are optimally oriented for reactivation under contemporary stress conditions and are thus likely to provide at least local increases in permeability.

  9. Discrete modeling of hydraulic fracturing processes in a complex pre-existing fracture network

    Science.gov (United States)

    Kim, K.; Rutqvist, J.; Nakagawa, S.; Houseworth, J. E.; Birkholzer, J. T.

    2015-12-01

    Hydraulic fracturing and stimulation of fracture networks are widely used by the energy industry (e.g., shale gas extraction, enhanced geothermal systems) to increase permeability of geological formations. Numerous analytical and numerical models have been developed to help understand and predict the behavior of hydraulically induced fractures. However, many existing models assume simple fracturing scenarios with highly idealized fracture geometries (e.g., propagation of a single fracture with assumed shapes in a homogeneous medium). Modeling hydraulic fracture propagation in the presence of natural fractures and homogeneities can be very challenging because of the complex interactions between fluid, rock matrix, and rock interfaces, as well as the interactions between propagating fractures and pre-existing natural fractures. In this study, the TOUGH-RBSN code for coupled hydro-mechanical modeling is utilized to simulate hydraulic fracture propagation and its interaction with pre-existing fracture networks. The simulation tool combines TOUGH2, a simulator of subsurface multiphase flow and mass transport based on the finite volume approach, with the implementation of a lattice modeling approach for geomechanical and fracture-damage behavior, named Rigid-Body-Spring Network (RBSN). The discrete fracture network (DFN) approach is facilitated in the Voronoi discretization via a fully automated modeling procedure. The numerical program is verified through a simple simulation for single fracture propagation, in which the resulting fracture geometry is compared to an analytical solution for given fracture length and aperture. Subsequently, predictive simulations are conducted for planned laboratory experiments using rock-analogue (soda-lime glass) samples containing a designed, pre-existing fracture network. The results of a preliminary simulation demonstrate selective fracturing and fluid infiltration along the pre-existing fractures, with additional fracturing in part

  10. Anisotropic characteristics of electrical responses of fractured reservoir with multiple sets of fractures

    Institute of Scientific and Technical Information of China (English)

    Shen Jinsong; Su Benyu; Guo Naichuan

    2009-01-01

    In fractured reservoirs, the fractures not only provide the storage space for hydrocarbons, but also form the main flow channels which connect the pores of the matrix, so fractures dominate the productivity of reservoirs.However, because of the heterogeneity and randomness of the distribution of fractures, exploration and evaluation of fractured reservoirs is still one of the most difficult problems in the oil industry.In recent years, seismic anisotropy has been applied to the assessment of fractured formations, whereas electrical anisotropy which is more intense in fractured formations than seismic anisotropy has not been studied or used so extensively.In this study, fractured reservoir models which considered multiple sets of fractures with smooth and partly closed, rough surfaces were established based on the fractures and pore network, and the vertical and horizontal electrical resistivities were derived as a function of the matrix and fracture porosities according to Ohm's law.By using the anisotropic resistivity equations, variations of the electrical anisotropy of three types of fractured models under the conditions of free pressure and confining pressure were analyzed through the variations of the exerted pressure, matrix porosity, fracture aperture and formation water resistivity.The differences of the vertical and horizontal resistivities and the anisotropy between the connected and non-connected fractures were also analyzed.It is known from the simulated results that an increase of the confining pressure causes a decrease of electrical anisotropy because of the elasticity of the closed fractures and the decrease of the fracture aperture.For a fixed fracture porosity, the higher the matrix porosity, the weaker the electrical anisotropy in the rock formation.

  11. Sapling herbivory, invertebrate herbivores and predators across a natural tree diversity gradient in Germany's largest connected deciduous forest.

    Science.gov (United States)

    Sobek, Stephanie; Scherber, Christoph; Steffan-Dewenter, Ingolf; Tscharntke, Teja

    2009-05-01

    Tree species-rich forests are hypothesised to be less susceptible to insect herbivores, but so far herbivory-diversity relationships have rarely been tested for tree saplings, and no such study has been published for deciduous forests in Central Europe. We expected that diverse tree communities reduce the probability of detection of host plants and increase abundance of predators, thereby reducing herbivory. We examined levels of herbivory suffered by beech (Fagus sylvatica L.) and maple saplings (Acer pseudoplatanus L. and Acer platanoides L.) across a tree species diversity gradient within Germany's largest remaining deciduous forest area, and investigated whether simple beech or mixed stands were less prone to damage caused by herbivorous insects. Leaf area loss and the frequency of galls and mines were recorded for 1,040 saplings (>13,000 leaves) in June and August 2006. In addition, relative abundance of predators was assessed to test for potential top-down control. Leaf area loss was generally higher in the two species of maple compared to beech saplings, while only beech showed a decline in damage caused by leaf-chewing herbivores across the tree diversity gradient. No significant patterns were found for galls and mines. Relative abundance of predators on beech showed a seasonal response and increased on species-rich plots in June, suggesting higher biological control. We conclude that, in temperate deciduous forests, herbivory-tree diversity relationships are significant, but are tree species-dependent with bottom-up and top-down control as possible mechanisms. In contrast to maple, beech profits from growing in a neighbourhood of higher tree richness, which implies that species identity effects may be of greater importance than tree diversity effects per se. Hence, herbivory on beech appeared to be mediated bottom-up by resource concentration in the sampled forest stands, as well as regulated top-down through biocontrol by natural enemies.

  12. [Acetabular fractures].

    Science.gov (United States)

    Gänsslen, A; Oestern, H J

    2011-12-01

    Treatment of acetabular fractures requires extensive knowledge of the bony anatomy, the amount of possible exposure of the bone with the selected approaches and fracture type-dependent indications of operative treatment. Classification of the fracture with detailed analysis of the fracture morphology is the basis for decision making and planning. The primary treatment aim is the anatomic reconstruction of the acetabulum which results in optimal long-term results.The basis of this overview is the presentation of standard treatment concepts in acetabular fracture surgery. Beside characteristics of the acetabular bony anatomy, biomechanical and pathomechanical principles and the relevant radiological anatomy, the treatment options, both conservative and operative and basic principles of the indications for standard surgical approaches will be discussed.The special fracture type is discussed in detail regarding incidence, injury mechanism, concomitant injuries, options for conservative and operative treatment, quality of operative reduction and long-term results.Furthermore, epidemiological data on typical postoperative complications are evaluated.

  13. An Unusual Combination of Acetabular and Pelvic Fracture: Is This a New Subtype of Acetabular Fracture?

    Directory of Open Access Journals (Sweden)

    Reza Tavakoli Darestani

    2013-01-01

    Full Text Available Introduction: Acetabular fractures are a common problem among young males. An acetabular fracture with disruption of the joint surface, if untreated, will rapidly lead to post-traumatic osteoarthritis. Proper reduction and internal fixation depend on accurate classification and the quality of imaging.Case Presentation: We present an unusual form of acetabular fracture, which is not included in the conventional classification (Judet and Letournel ; this occurred in a middle-aged male who was operatively treated without any complications. In this case due to posterior extension of the fracture into the SI joint and concomitant anterior column fracture in the area above the acetabular dome, no portion of the acetabular anterior surface remained connected to the innominate bone.Conclusions: We recognized this type of fracture and treated it similarly to both column fractures. We recommend that the classification of acetabular fractures be modified to include this type of fracture.

  14. Sports fractures.

    OpenAIRE

    DeCoster, T. A.; Stevens, M. A.; Albright, J. P.

    1994-01-01

    Fractures occur in athletes and dramatically influence performance during competitive and recreational activities. Fractures occur in athletes as the result of repetitive stress, acute sports-related trauma and trauma outside of athletics. The literature provides general guidelines for treatment as well as a variety of statistics on the epidemiology of fractures by sport and level of participation. Athletes are healthy and motivated patients, and have high expectations regarding their level o...

  15. Hamate fractures.

    Science.gov (United States)

    Sarabia Condés, J M; Ibañez Martínez, L; Sánchez Carrasco, M A; Carrillo Julia, F J; Salmerón Martínez, E L

    2015-01-01

    The purpose of this paper is to present our experience in the treatment of the fractures of the hamate and to make a review of the literature on this topic. We retrospectively reviewed 10 patients treated in our clinic between 2005-2012 suffering from fractures of the hamate. Six cases were fractures of the body and four were fractures of the hamate. Five cases were of associated injuries. Diagnostic delay ranged from 30 days to 2 years. Patient follow-up ranged from 1 to 10 years. Patient satisfaction was evaluated using the DASH questionnaire. Five patients with a fracture of the body underwent surgery, and one was treated conservatively. Two patients with fracture of the hook of the hamate were treated with immobilization, and two more patients had the fragment removed. The grip strength and the digital clip were reduced in 2 cases. Flexion and extension of the wrist was limited in 3 cases. The mobility of the fingers was normal in all the cases, except in one. The results obtained from the DASH questionnaire were normal in all the cases, except in one case of fracture of the hamate, and in two cases of fracture of the body. The surgical treatment should reduce the dislocation and stabilize the injuries with osteosynthesis. The fractures of the hamate are usually diagnosed late, and the most recommended treatment is removal of the fragment, although it cannot be deduced from this study. Copyright © 2014 SECOT. Published by Elsevier Espana. All rights reserved.

  16. Colles Fracture

    OpenAIRE

    Sánchez León, Belisario; Facultad de Medicina, Universidad Nacional Mayor de San Marcos, Lima, Perú

    2014-01-01

    Our expertise is the study of more than 2,000 cases of Colles' fractures. Colles name should in this case to synthesize the type of fractures of the lower end of the radius. There have been various proposed classifications according to the different fracture lines can be demonstrated radiologically in the region of the wrist. We believe that these ratings should only be retained if the concept of the articular fracture or not in the classical sense, since it has great value in the functional ...

  17. The functional potential of microbial communities in hydraulic fracturing source water and produced water from natural gas extraction characterized by metagenomic sequencing.

    Science.gov (United States)

    Mohan, Arvind Murali; Bibby, Kyle J; Lipus, Daniel; Hammack, Richard W; Gregory, Kelvin B

    2014-01-01

    Microbial activity in produced water from hydraulic fracturing operations can lead to undesired environmental impacts and increase gas production costs. However, the metabolic profile of these microbial communities is not well understood. Here, for the first time, we present results from a shotgun metagenome of microbial communities in both hydraulic fracturing source water and wastewater produced by hydraulic fracturing. Taxonomic analyses showed an increase in anaerobic/facultative anaerobic classes related to Clostridia, Gammaproteobacteria, Bacteroidia and Epsilonproteobacteria in produced water as compared to predominantly aerobic Alphaproteobacteria in the fracturing source water. The metabolic profile revealed a relative increase in genes responsible for carbohydrate metabolism, respiration, sporulation and dormancy, iron acquisition and metabolism, stress response and sulfur metabolism in the produced water samples. These results suggest that microbial communities in produced water have an increased genetic ability to handle stress, which has significant implications for produced water management, such as disinfection.

  18. Well Test Analysis of Naturally Fractured Vuggy Reservoirs with an Analytical Triple Porosity – Double Permeability Model and a Global Optimization Method

    Directory of Open Access Journals (Sweden)

    Gómez Susana

    2014-07-01

    Full Text Available The aim of this work is to study the automatic characterization of Naturally Fractured Vuggy Reservoirs via well test analysis, using a triple porosity-dual permeability model. The inter-porosity flow parameters, the storativity ratios, as well as the permeability ratio, the wellbore storage effect, the skin and the total permeability will be identified as parameters of the model. In this work, we will perform the well test interpretation in Laplace space, using numerical algorithms to transfer the discrete real data given in fully dimensional time to Laplace space. The well test interpretation problem in Laplace space has been posed as a nonlinear least squares optimization problem with box constraints and a linear inequality constraint, which is usually solved using local Newton type methods with a trust region. However, local methods as the one used in our work called TRON or the well-known Levenberg-Marquardt method, are often not able to find an optimal solution with a good fit of the data. Also well test analysis with the triple porosity-double permeability model, like most inverse problems, can yield multiple solutions with good match to the data. To deal with these specific characteristics, we will use a global optimization algorithm called the Tunneling Method (TM. In the design of the algorithm, we take into account issues of the problem like the fact that the parameter estimation has to be done with high precision, the presence of noise in the measurements and the need to solve the problem computationally fast. We demonstrate that the use of the TM in this study, showed to be an efficient and robust alternative to solve the well test characterization, as several optimal solutions, with very good match to the data were obtained.

  19. Fractured reservoir analogs: case study of paelocirculation markers on Tamariu's Granite.

    Science.gov (United States)

    Bertrand, Lionel; Legarzic, Edouard; Geraud, Yves; Diraison, Marc

    2013-04-01

    In fractured crystalline reservoirs, the grain matrix has in general a very low permeability and the fluid flow is localized in the fracture pattern. The flow in such fracture network is generally complicated to characterize, in on hand because many parameters (length, connectivity, aperture, tortuosity,…) are acting on the fluid flow, in other hand because the fractures at a reservoir scale using seismic data are not easy to characterize. In fact, the only information we have on fracture in buried reservoir are at a local scale with boreholes and at a kilometric scale with seismic. The study of field analogs is one way to establish a better comprehension of the fracture pattern between those two scales. Regional and outcrop studies on Tamariu's granite, which outcrops on the Catalonian Coastal Ranges, has permit the characterization of the faults and fractures at different scales. The faults network defines different sizes of structural blocks bordered by faults. In an unfaulted structural block, the granite exhibits a fracture network filled with hydrothermal carbonates, markers of important paleofluid circulation. These carbonates were analysed at different scales using fracture mapping, calcimetry and microscopy on thin- sections in order to define the location and the volume of the carbonates precipitation and to have an estimation of the paleo-porosity used by the fluids in the fracture network. With precise fracture maps, we analysed the principal flow direction and the nature of the hydrothermal deposits. The same maps, combined with calcimetry measurements, allow us to quantify the 2D volume of porosity used by the paleofluids. We have quantified the carbonates in different areas of percolation: the main veins, breccias cimented by carbonates, fractured granite and poorly fractured granite. The percentage of paleofluids markers reaches to 3% of the granitic rock, and the main part of them are localized in some fractured corridor composed of mains veins

  20. Complex Fluids and Hydraulic Fracturing.

    Science.gov (United States)

    Barbati, Alexander C; Desroches, Jean; Robisson, Agathe; McKinley, Gareth H

    2016-06-07

    Nearly 70 years old, hydraulic fracturing is a core technique for stimulating hydrocarbon production in a majority of oil and gas reservoirs. Complex fluids are implemented in nearly every step of the fracturing process, most significantly to generate and sustain fractures and transport and distribute proppant particles during and following fluid injection. An extremely wide range of complex fluids are used: naturally occurring polysaccharide and synthetic polymer solutions, aqueous physical and chemical gels, organic gels, micellar surfactant solutions, emulsions, and foams. These fluids are loaded over a wide range of concentrations with particles of varying sizes and aspect ratios and are subjected to extreme mechanical and environmental conditions. We describe the settings of hydraulic fracturing (framed by geology), fracturing mechanics and physics, and the critical role that non-Newtonian fluid dynamics and complex fluids play in the hydraulic fracturing process.

  1. Eggshell membrane: A possible new natural therapeutic for joint and connective tissue disorders. Results from two open-label human clinical studies

    Directory of Open Access Journals (Sweden)

    Kevin J Ruff

    2009-05-01

    Full Text Available Kevin J Ruff1, Dale P DeVore2, Michael D Leu3, Mark A Robinson41ESM Technologies, LLC, Carthage, MO, USA; 2Membrell, LLC, Carthage, MO, USA; 3Private Practice, Jenks, OK, USA; 4Robinson Family Health Center, Carthage, MO, USABackground: Natural Eggshell Membrane (NEM® is a novel dietary supplement that contains naturally occurring glycosaminoglycans and proteins essential for maintaining healthy joint and connective tissues. Two single center, open-label human clinical studies were conducted to evaluate the efficacy and safety of NEM® as a treatment for pain and inflexibility associated with joint and connective tissue disorders. Methods: Eleven (single-arm trial and 28 (double-arm trial patients received oral NEM® 500 mg once daily for four weeks. The primary outcome measure was to evaluate the change in general pain associated with the treatment joints/areas (both studies. In the single-arm trial, range of motion (ROM and related ROM-associated pain was also evaluated. The primary treatment response endpoints were at seven and 30 days. Both clinical assessments were performed on the intent-to-treat (ITT population within each study.Results: Single-arm trial: Supplementation with NEM® produced a significant treatment response at seven days for flexibility (27.8% increase; P = 0.038 and at 30 days for general pain (72.5% reduction; P = 0.007, flexibility (43.7% increase; P = 0.006, and ROM-associated pain (75.9% reduction; P = 0.021. Double-arm trial: Supplementation with NEM® produced a significant treatment response for pain at seven days for both treatment arms (X: 18.4% reduction; P = 0.021. Y: 31.3% reduction; P = 0.014. There was no clinically meaningful difference between treatment arms at seven days, so the Y arm crossed over to the X formulation for the remainder of the study. The significant treatment response continued through 30 days for pain (30.2% reduction; P = 0.0001. There were no adverse events reported during either

  2. Fracture Mechanics

    CERN Document Server

    Zehnder, Alan T

    2012-01-01

    Fracture mechanics is a vast and growing field. This book develops the basic elements needed for both fracture research and engineering practice. The emphasis is on continuum mechanics models for energy flows and crack-tip stress- and deformation fields in elastic and elastic-plastic materials. In addition to a brief discussion of computational fracture methods, the text includes practical sections on fracture criteria, fracture toughness testing, and methods for measuring stress intensity factors and energy release rates. Class-tested at Cornell, this book is designed for students, researchers and practitioners interested in understanding and contributing to a diverse and vital field of knowledge. Alan Zehnder joined the faculty at Cornell University in 1988. Since then he has served in a number of leadership roles including Chair of the Department of Theoretical and Applied Mechanics, and Director of the Sibley School of Mechanical and Aerospace Engineering.  He teaches applied mechanics and his research t...

  3. natural

    Directory of Open Access Journals (Sweden)

    Elías Gómez Macías

    2006-01-01

    Full Text Available Partiendo de óxido de magnesio comercial se preparó una suspensión acuosa, la cual se secó y calcinó para conferirle estabilidad térmica. El material, tanto fresco como usado, se caracterizó mediante DRX, área superficial BET y SEM-EPMA. El catalizador mostró una matriz de MgO tipo periclasa con CaO en la superficie. Las pruebas de actividad catalítica se efectuaron en lecho fijo empacado con partículas obtenidas mediante prensado, trituración y clasificación del material. El flujo de reactivos consistió en mezclas gas natural-aire por debajo del límite inferior de inflamabilidad. Para diferentes flujos y temperaturas de entrada de la mezcla reactiva, se midieron las concentraciones de CH4, CO2 y CO en los gases de combustión con un analizador de gases tipo infrarrojo no dispersivo (NDIR. Para alcanzar conversión total de metano se requirió aumentar la temperatura de entrada al lecho a medida que se incrementó el flujo de gases reaccionantes. Los resultados obtenidos permiten desarrollar un sistema de combustión catalítica de bajo costo con un material térmicamente estable, que promueva la alta eficiencia en la combustión de gas natural y elimine los problemas de estabilidad, seguridad y de impacto ambiental negativo inherentes a los procesos de combustión térmica convencional.

  4. Model to predict the flow of tracers in naturally fractured geothermal reservoirs; Modelo para predecir el flujo de trazadores en yacimientos geotermicos naturalmente fracturados

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez Sabag, Jetzabeth

    1988-02-01

    The proposed model has been developed to study the flow of tracers through naturally fractured geothermal reservoirs. The idealized system of the reservoir is made up of two regions: A movable region, where diffusion and convection mechanisms are present and a stagnant or immovable region where the diffusion and adsorption mechanisms are considered: in both regions the loss of mass by radioactive decay is considered. The solutions of the basic flow equations are in the Laplace space and for its numerical inversion the Stehfest algorithm was used. In spite of the numerical dispersion that these solutions involve, a well defined tendency to infer the system behavior under different flow conditions was found. It was found that, for practical purposes, the size of the matrix blocks does not have an influence on the concentration response, and the solution is reduced to the one presented by Tang and associates. Under these conditions, the system behavior can be described by two non-dimensional parameters: The Peclet number in fractures, P{sub e1}, and a parameter. The tracer response for the peak solution was also derived. An analytical solution limit was found for the case in which {alpha} tends to zero, which corresponds to the case of a homogenous system. It was verified that this limit solution is valid, for {alpha}<0.01. For the case of continuous injection, this solution is reduced to the one presented by Coasts and Smith. For the peak solution, it was found that the irruption time corresponding to the maximum concentration is directly related to the non-dimensional group. Therefore, it is possible to obtain the value of P{sub e1} for a given X{sub D}, or vice versa. A group of graphs of non-dimensional concentration in the fracture versus non-dimensional time, was developed. It was found that if P{sub e1} remains constant whereas {alpha} changes, the limit solution is the envelope of a family of curves in a graph of C{sub D} versus t{sub D}. In this figure P

  5. Shock-induced borehole waves in fractured formations

    NARCIS (Netherlands)

    Fan, H.

    2014-01-01

    Natural or hydraulic fractures are of major importance for the productivity of hydrocarbon reservoirs. Besides fracture detection, also the aperture and extension of the fractures are essential for a correct reservoir productivity estimate. There are many ways to detect and measure fractures, such a

  6. Galeazzi fractures and dislocations.

    Science.gov (United States)

    Giannoulis, Filippos S; Sotereanos, Dean G

    2007-05-01

    In 1934, fractures of the middle and distal third of the radius associated with instability of the distal radial ulnar joint (DRUJ) were described by Galeazzi. This type of lesion is characterized by its unstable nature and the need for open reduction and internal fixation to achieve a satisfactory functional outcome. A high index of suspicion should be maintained by the surgeon, and a thorough examination for instability of the DRUJ must be conducted. The marked instability of this fracture-dislocation complex is further enhanced by the disruption of the triangular fibrocartilage complex, either with or without ulna styloid fracture. Treatment in adults is surgical, and both bone and soft tissue injuries should be addressed.

  7. Fracture Rates and Fracture Sites in Patients With Osteogenesis Imperfecta

    DEFF Research Database (Denmark)

    Folkestad, Lars; Hald, Jannie Dahl; Ersbøll, Annette Kjær;

    2017-01-01

    Osteogenesis imperfecta (OI) is a hereditary, clinically heterogeneous, connective tissue disorder. The population prevalence of OI in Denmark is 10.6 in 100,000. A hallmark of the disease is frequent fractures that are often precipitated by minimal trauma. The aim of the current study...

  8. Growth Kinematics of Opening-Mode Fractures

    Science.gov (United States)

    Eichhubl, P.; Alzayer, Y.; Laubach, S.; Fall, A.

    2014-12-01

    Fracture aperture is a primary control on flow in fractured reservoirs of low matrix permeability including unconventional oil and gas reservoirs and most geothermal systems. Guided by principles of linear elastic fracture mechanics, fracture aperture is generally assumed to be a linear function of fracture length and elastic material properties. Natural opening-mode fractures with significant preserved aperture are observed in core and outcrop indicative of fracture opening strain accommodated by permanent solution-precipitation creep. Fracture opening may thus be decoupled from length growth if the material effectively weakens after initial elastic fracture growth by either non-elastic deformation processes or changes in elastic properties. To investigate the kinematics of fracture length and aperture growth, we reconstructed the opening history of three opening-mode fractures that are bridged by crack-seal quartz cement in Travis Peak Sandstone of the SFOT-1 well, East Texas. Similar crack-seal cement bridges had been interpreted to form by repeated incremental fracture opening and subsequent precipitation of quartz cement. We imaged crack-seal cement textures for bridges sampled at varying distance from the tips using scanning electron microscope cathodoluminescence, and determined the number and thickness of crack-seal cement increments as a function of position along the fracture length and height. Observed trends in increment number and thickness are consistent with an initial stage of fast fracture propagation relative to aperture growth, followed by a stage of slow propagation and pronounced aperture growth. Consistent with fluid inclusion observations indicative of fracture opening and propagation occurring over 30-40 m.y., we interpret the second phase of pronounced aperture growth to result from fracture opening strain accommodated by solution-precipitation creep and concurrent slow, possibly subcritical, fracture propagation. Similar deformation

  9. Fracture mechanics

    CERN Document Server

    Perez, Nestor

    2017-01-01

    The second edition of this textbook includes a refined presentation of concepts in each chapter, additional examples; new problems and sections, such as conformal mapping and mechanical behavior of wood; while retaining all the features of the original book. The material included in this book is based upon the development of analytical and numerical procedures pertinent to particular fields of linear elastic fracture mechanics (LEFM) and plastic fracture mechanics (PFM), including mixed-mode-loading interaction. The mathematical approach undertaken herein is coupled with a brief review of several fracture theories available in cited references, along with many color images and figures. Dynamic fracture mechanics is included through the field of fatigue and Charpy impact testing. Explains computational and engineering approaches for solving crack-related problems using straightforward mathematics that facilitate comprehension of the physical meaning of crack growth processes; Expands computational understandin...

  10. Fracture mechanics

    Science.gov (United States)

    Shannon, John L., Jr.

    1986-01-01

    The application of fracture mechanics to the design of ceramic structures will require the precise measurement of crack growth and fracture resistance of these materials over their entire range of anticipated service temperatures and standardized test methods for making such measurements. The development of a standard test for measuring the plane strain fracture toughness is sought. Stress intensity factor coefficients were determined for three varieties of chevron-notch specimens, and fracture toughness measurements were made on silicon nitrides, silicon carbides, and aluminum oxides to assess the performance of each specimen variety. It was determined that silicon nitride and silicon carbides have flat crack growth resistance curves, but aluminum oxide does not. Additionally, batch-to-batch differences were noticed for the aluminum oxide. Experiments are continuing to explain the rising crack growth resistance and batch-to-batch variations for the aluminum oxide.

  11. Connected Traveler

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Alex

    2015-11-01

    The Connected Traveler project is a multi-disciplinary undertaking that seeks to validate potential for transformative transportation system energy savings by incentivizing efficient traveler behavior. This poster outlines various aspects of the Connected Traveler project, including market opportunity, understanding traveler behavior and decision-making, automation and connectivity, and a projected timeline for Connected Traveler's key milestones.

  12. Analysis of the hydraulic data from the MI fracture zone at the Grimsel Rock Laboratory, Switzerland

    Energy Technology Data Exchange (ETDEWEB)

    Davey, A.; Karasaki, K.; Long, J.C.S.; Landsfeld, M.; Mensch, A.; Martel, S.J.

    1989-10-01

    One of the major problems in analyzing flow and transport in fractured rock is that the flow may be largely confined to a poorly connected network of fractures. In order to overcome some of this problem, Lawrence Berkeley Laboratory (LBL) has been developing a new type of fracture hydrology model called an equivalent discontinuum model. In this model the authors represent the discontinuous nature of the problem through flow on a partially filled lattice. A key component in constructing an equivalent discontinuum model from this lattice is removing some of the conductive elements such that the system is partially connected in the same manner as the fracture network. This is done through a statistical inverse technique called simulated annealing. The fracture network model is annealed by continually modifying a base model, or template such that the modified systems behave more and more like the observed system. In order to see how the simulated annealing algorithm works, the authors have developed a series of synthetic real cases. In these cases, the real system is completely known so that the results of annealing to steady state data can be evaluated absolutely. The effect of the starting configuration has been studied by varying the percent of conducting elements in the initial configuration. Results have shown that the final configurations converge to about the same percentage of conducting elements. An example using Nagra field data from the Migration Experiment (MI) at Grimsel Rock Laboratory in Switzerland is also analyzed. 24 refs., 33 figs., 3 tabs.

  13. Advanced reservoir characterization and evaluation of CO{sub 2} gravity drainage in the naturally fractured Spraberry Trend Area. First annual technical progress report, September 1, 1995--August 31, 1996

    Energy Technology Data Exchange (ETDEWEB)

    Schechter, D.S.

    1996-12-17

    The overall goal of this project is to assess the economic feasibility of CO{sub 2} flooding the naturally fractured Spraberry Trend Area in West Texas. This objective is being accomplished by conducting research in four areas: (1) extensive characterization of the reservoirs, (2) experimental studies of crude oil/brine/rock (COBR) interaction in the reservoirs, (3) analytical and numerical simulation of Spraberry reservoirs, and, (4) experimental investigations on CO{sub 2} gravity drainage in Spraberry whole cores. This report provides results of the first year of the five-year project for each of the four areas.

  14. Modeling 3D Fracture Network in Carbonate NFR: Contribution from an Analogue Dataset, the Cante Perdrix Quarry, Calvisson, SE France

    NARCIS (Netherlands)

    Gauthier, B.D.M.; Bisdom, K.; Bertotti, G.

    2012-01-01

    The full 3D characterization of fracture networks is a key issue in naturally fractured reservoir modeling. Fracture geometry (e.g., orientation, size, spacing), fracture scale (e.g., bed-confined fractures, fracture corridors), lateral and vertical variations, need to be defined from limited, gener

  15. Fractal characterization of fracture networks: An improved box-counting technique

    Science.gov (United States)

    Roy, Ankur; Perfect, Edmund; Dunne, William M.; McKay, Larry D.

    2007-12-01

    Box counting is widely used for characterizing fracture networks as fractals and estimating their fractal dimensions (D). If this analysis yields a power law distribution given by N ∝ r-D, where N is the number of boxes containing one or more fractures and r is the box size, then the network is considered to be fractal. However, researchers are divided in their opinion about which is the best box-counting algorithm to use, or whether fracture networks are indeed fractals. A synthetic fractal fracture network with a known D value was used to develop a new algorithm for the box-counting method that returns improved estimates of D. The method is based on identifying the lower limit of fractal behavior (rcutoff) using the condition ds/dr → 0, where s is the standard deviation from a linear regression equation fitted to log(N) versus log(r) with data for r sequentially excluded. A set of 7 nested fracture maps from the Hornelen Basin, Norway was used to test the improved method and demonstrate its accuracy for natural patterns. We also reanalyzed a suite of 17 fracture trace maps that had previously been evaluated for their fractal nature. The improved estimates of D for these maps ranged from 1.56 ± 0.02 to 1.79 ± 0.02, and were much greater than the original estimates. These higher D values imply a greater degree of fracture connectivity and thus increased propensity for fracture flow and the transport of miscible or immiscible chemicals.

  16. Elastic waves along a fracture intersection

    Science.gov (United States)

    Abell, Bradley Charles

    Fractures and fracture networks play a significant role in the subsurface hydraulic connectivity within the Earth. While a significant amount of research has been performed on the seismic response of single fractures and sets of fractures, few studies have examined the effect of fracture intersections on elastic wave propagation. Intersections play a key role in the connectivity of a fracture network that ultimately affects the hydraulic integrity of a rock mass. In this dissertation two new types of coupled waves are examined that propagate along intersections. 1) A coupled wedge wave that propagates along a surface fracture with particle motion highly localized to the intersection of a fracture with a free surface, and 2) fracture intersection waves that propagate along the intersection between two orthogonal fractures. Theoretical formulations were derived to determine the particle motion and velocity of intersection waves. Vibrational modes calculated from the theoretical formulation match those predicted by group theory based on the symmetry of the problem. For the coupled wedge wave, two vibrational modes exist that range in velocity between the wedge wave and Rayleigh wave velocity and exhibit either wagging or breathing motion depending on the Poisson's ratio. For the intersection waves, the observed modes depend on the properties of the fractures forming the intersection. If both fractures have equal stiffness four modes exist, two with wagging and two with breathing motion. If the fractures have unequal stiffness, four modes also exist, but the motion depends on the Poisson's ratio. The velocity of intersection waves depends on the coupling or stiffness of the intersection and frequency of the signal. In general, the different modes travel with speeds between the wedge wave and bulk shear wave velocity. Laboratory experiments were performed on isotropic and anisotropic samples to verify the existence of these waves. For both waves, the observed signals

  17. Connecting the Pioneers, Current Leaders and the Nature and History of Space Weather with K-12 Classrooms and the General Public

    Science.gov (United States)

    Ng, C.; Thompson, B. J.; Cline, T.; Lewis, E.; Barbier, B.; Odenwald, S.; Spadaccini, J.; James, N.; Stephenson, B.; Davis, H. B.; Major, E. R.; Space Weather Living History

    2011-12-01

    The Space Weather Living History program will explore and share the breakthrough new science and captivating stories of space environments and space weather by interviewing space physics pioneers and leaders active from the International Geophysical Year (IGY) to the present. Our multi-mission project will capture, document and preserve the living history of space weather utilizing original historical materials (primary sources). The resulting products will allow us to tell the stories of those involved in interactive new media to address important STEM needs, inspire the next generation of explorers, and feature women as role models. The project is divided into several stages, and the first stage, which began in mid-2011, focuses on resource gathering. The goal is to capture not just anecdotes, but the careful analogies and insights of researchers and historians associated with the programs and events. The Space Weather Living History Program has a Scientific Advisory Board, and with the Board's input our team will determine the chronology, key researchers, events, missions and discoveries for interviews. Education activities will be designed to utilize autobiographies, newspapers, interviews, research reports, journal articles, conference proceedings, dissertations, websites, diaries, letters, and artworks. With the help of a multimedia firm, we will use some of these materials to develop an interactive timeline on the web, and as a downloadable application in a kiosk and on tablet computers. In summary, our project augments the existing historical records with education technologies, connect the pioneers, current leaders and the nature and history of space weather with K-12 classrooms and the general public, covering all areas of studies in Heliophysics. The project is supported by NASA award NNX11AJ61G.

  18. Naturally fractured reservoirs: Optimized E and P strategies using a reaction-transport-mechanical simulator in an integrated approach. Annual report, 1996--1997

    Energy Technology Data Exchange (ETDEWEB)

    Hoak, T.; Jenkins, R. [Science Applications International Corp., McLean, VA (United States); Ortoleva, P.; Ozkan, G.; Shebl, M.; Sibo, W.; Tuncay, K. [Laboratory for Computational Geodynamics (United States); Sundberg, K. [Phillips Petroleum Company (United States)

    1998-07-01

    The methodology and results of this project are being tested using the Andector-Goldsmith Field in the Permian Basin, West Texas. The study area includes the Central Basin Platform and the Midland Basin. The Andector-Goldsmith Field lies at the juncture of these two zones in the greater West Texas Permian Basin. Although the modeling is being conducted in this area, the results have widespread applicability to other fractured carbonate and other reservoirs throughout the world.

  19. Effects of fracture distribution and length scale on the equivalent continuum elastic compliance of fractured rock masses

    Institute of Scientific and Technical Information of China (English)

    Marte Gutierrez; Dong-Joon Youn

    2015-01-01

    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 distribu-tions 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.

  20. 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.

  1. Galeazzi fracture.

    Science.gov (United States)

    Atesok, Kivanc I; Jupiter, Jesse B; Weiss, Arnold-Peter C

    2011-10-01

    Galeazzi fracture is a fracture of the radial diaphysis with disruption at the distal radioulnar joint (DRUJ). Typically, the mechanism of injury is forceful axial loading and torsion of the forearm. Diagnosis is established on radiographic evaluation. Underdiagnosis is common because disruption of the ligamentous restraints of the DRUJ may be overlooked. Nonsurgical management with anatomic reduction and immobilization in a long-arm cast has been successful in children. In adults, nonsurgical treatment typically fails because of deforming forces acting on the distal radius and DRUJ. Open reduction and internal fixation is the preferred surgical option. Anatomic reduction and rigid fixation should be followed by intraoperative assessment of the DRUJ. Further intraoperative interventions are based on the reducibility and postreduction stability of the DRUJ. Misdiagnosis or inadequate management of Galeazzi fracture may result in disabling complications, such as DRUJ instability, malunion, limited forearm range of motion, chronic wrist pain, and osteoarthritis.

  2. Eccentric connectivity index

    CERN Document Server

    Ilić, Aleksandar

    2011-01-01

    The eccentric connectivity index $\\xi^c$ is a novel distance--based molecular structure descriptor that was recently used for mathematical modeling of biological activities of diverse nature. It is defined as $\\xi^c (G) = \\sum_{v \\in V (G)} deg (v) \\cdot \\epsilon (v)$\\,, where $deg (v)$ and $\\epsilon (v)$ denote the vertex degree and eccentricity of $v$\\,, respectively. We survey some mathematical properties of this index and furthermore support the use of eccentric connectivity index as topological structure descriptor. We present the extremal trees and unicyclic graphs with maximum and minimum eccentric connectivity index subject to the certain graph constraints. Sharp lower and asymptotic upper bound for all graphs are given and various connections with other important graph invariants are established. In addition, we present explicit formulae for the values of eccentric connectivity index for several families of composite graphs and designed a linear algorithm for calculating the eccentric connectivity in...

  3. On eccentric connectivity index

    CERN Document Server

    Zhou, Bo

    2010-01-01

    The eccentric connectivity index, proposed by Sharma, Goswami and Madan, has been employed successfully for the development of numerous mathematical models for the prediction of biological activities of diverse nature. We now report mathematical properties of the eccentric connectivity index. We establish various lower and upper bounds for the eccentric connectivity index in terms of other graph invariants including the number of vertices, the number of edges, the degree distance and the first Zagreb index. We determine the n-vertex trees of diameter with the minimum eccentric connectivity index, and the n-vertex trees of pendent vertices, with the maximum eccentric connectivity index. We also determine the n-vertex trees with respectively the minimum, second-minimum and third-minimum, and the maximum, second-maximum and third-maximum eccentric connectivity indices for

  4. Fracture Blisters

    Directory of Open Access Journals (Sweden)

    Uebbing, Claire M

    2011-02-01

    Full Text Available Fracture blisters are a relatively uncommon complication of fractures in locations of the body, such as the ankle, wrist elbow and foot, where skin adheres tightly to bone with little subcutaneous fat cushioning. The blister that results resembles that of a second degree burn.These blisters significantly alter treatment, making it difficult to splint or cast and often overlying ideal surgical incision sites. Review of the literature reveals no consensus on management; however, most authors agree on early treatment prior to blister formation or delay until blister resolution before attempting surgical correction or stabilization. [West J Emerg Med. 2011;12(1;131-133.

  5. Connecting Grammaticalisation

    DEFF Research Database (Denmark)

    Nørgård-Sørensen, Jens; Heltoft, Lars; Schøsler, Lene

    morphological, topological and constructional paradigms often connect to form complex paradigms. The book introduces the concept of connecting grammaticalisation to describe the formation, restructuring and dismantling of such complex paradigms. Drawing primarily on data from Germanic, Romance and Slavic...

  6. Hand Fractures

    Science.gov (United States)

    ... Z Videos Infographics Symptom Picker Anatomy Bones Joints Muscles Nerves Vessels Tendons About Hand Surgery What is a Hand Surgeon? What is ... serve as a framework. This framework supports the muscles that make the wrist ... When one of these hand bones is broken (fractured), it can prevent you ...

  7. Fracture source

    Directory of Open Access Journals (Sweden)

    2003-07-01

    Full Text Available The fracture properties of many different types of fibers are covered in a timely new book that will prove to be a tremendous source of information and references for researchers in the wide and diverse field of fibers and composites, says Bill Clegg.

  8. Rib Fractures

    Science.gov (United States)

    ... Commentary Recent News Scientists Working on Solar-Powered Prosthetic Limbs Exercise a Great Prescription to Help Older Hearts Bavencio Approved for Rare Skin Cancer Older Mothers May Raise Better-Behaved Kids, Study ... or a collapsed lung (pneumothorax—see Traumatic Pneumothorax ). An injury that fractures the lower ribs sometimes also damages the liver (see Liver ...

  9. [Thoracolumbar fractures].

    Science.gov (United States)

    Freslon, M; Bouaka, D; Coipeau, P; Defossez, G; Leclercq, N; Nebout, J; Marteau, E; Poilbout, N; Prebet, R

    2008-06-01

    Thoracolumbar fractures are frequent and the functional outcomes are sometimes severe. This multicentric study, including five medical centers, was performed to evaluate the long-term outcomes of the patients. One hundred and thirty six patients with thoracolumbar fracture (T11 to L2) was evaluated with a minimal follow-up of two years. Every one had a clinical exam with a score of Oswestry and an X-Ray study (before and after treatment and at revision). Most of them presented compression fractures, the most often at L1 level. On X-rays, a gain was noted on the vertebral kyphosis immediately after surgery, but there is a loss of correction over time whatever the treatment. The clinical outcomes for the patients were great, with an Oswestry average score of 6,4. A correlation was noted between this functional score and vertebral kyphosis. So, an anterior column strengthening (isolated or performed during the surgery) could improve these functional outcomes. Moreover, the Thoraco Lumbar Injury Severity Score (TLISS) seems to be a simple organigram to determine the most appropriate treatment of these fractures, with particular attention to the distraction mechanism or posterior ligamentous complex lesions. However, RMI before surgery is necessary to evaluate these lesions.

  10. Seismological investigation of crack formation in hydraulic rock fracturing experiments and in natural geothermal environments. Progress report, September 1, 1980-August 31, 1981

    Energy Technology Data Exchange (ETDEWEB)

    Aki, K.

    1981-09-01

    Progress is reported on the following: interpretation of seismic data from hydraulic fracturing experiments at the Fenton Hill Hot Dry Rock Geothermal Site, interpretation of 3-D velocity anomalies in the western US with special attention to geothermal areas, theoretical and observational studies of scattering and attenuation of high-frequency seismic waves, theoretical and observational studies of volcanic tremors in relation to magma transport mechanisms, and deployment and maintenance of 9 event-recorders around Mt. St. Helens. Abstracts of papers submitted for publication are included. (MHR)

  11. Intelligent fracture creation for shale gas development

    KAUST Repository

    Douglas, Craig C.

    2011-05-14

    Shale gas represents a major fraction of the proven reserves of natural gas in the United States and a collection of other countries. Higher gas prices and the need for cleaner fuels provides motivation for commercializing shale gas deposits even though the cost is substantially higher than traditional gas deposits. Recent advances in horizontal drilling and multistage hydraulic fracturing, which dramatically lower costs of developing shale gas fields, are key to renewed interest in shale gas deposits. Hydraulically induced fractures are quite complex in shale gas reservoirs. Massive, multistage, multiple cluster treatments lead to fractures that interact with existing fractures (whether natural or induced earlier). A dynamic approach to the fracturing process so that the resulting network of reservoirs is known during the drilling and fracturing process is economically enticing. The process needs to be automatic and done in faster than real-time in order to be useful to the drilling crews.

  12. Characterization of a hydraulically induced bedrock fracture

    OpenAIRE

    2014-01-01

    Hydraulic fracturing is a controversial practice because of concerns about environmental impacts due to its widespread use in recovering unconventional petroleum and natural gas deposits. However, water-only hydraulic fracturing has been used safely and successfully for many years to increase the permeability of aquifers used for drinking and irrigation water supply. This process extends and widens existing bedrock fractures, allowing groundwater storage to increase. Researchers have studied ...

  13. Diagenesis in porosity evolution of opening-mode fractures, Middle Triassic to Lower Jurassic La Boca Formation, NE Mexico

    Science.gov (United States)

    Laubach, Stephen E.; Ward, Meghan E.

    2006-06-01

    Opening-mode fractures (joints) in Middle Triassic to Lower Jurassic La Boca Formation sandstones, northeastern Mexico, have patterns of fracture porosity, mineral-fill structures, and size distributions not previously described from outcrop. Patterns match those found in cores from many basins. We used aperture measurements along lines of observation (scanlines), fracture-trace maps, petrography, high-resolution scanning-electron-microscope-(SEM)-based cathodoluminescence, and fluid inclusions to characterize fracture populations. Open fractures are lined by quartz that precipitated while fractures were opening, whereas sealed fractures additionally contain calcite deposited after fractures ceased opening. Large fractures and arrays of contemporaneous microfractures have consistent power-law aperture-size scaling over approximately three orders of magnitude. Our results imply that open fractures and fracture sizes depend on diagenetic state. The interplay of fracture mechanics and diagenetic history is a determinant on effective porosity within fractures and, thus, open fracture persistence, connectivity, and fluid flow.

  14. Acidization of shales with calcite cemented fractures

    Science.gov (United States)

    Kwiatkowski, Kamil; Szymczak, Piotr; Jarosiński, Marek

    2017-04-01

    Investigation of cores drilled from shale formations reveals a relatively large number of calcite-cemented fractures. Usually such fractures are reactivated during fracking and can contribute considerably to the permeability of the resulting fracture network. However, calcite coating on their surfaces effectively excludes them from production. Dissolution of the calcite cement by acidic fluids is investigated numerically with focus on the evolution of fracture morphology. Available surface area, breakthrough time, and reactant penetration length are calculated. Natural fractures in cores from Pomeranian shale formation (northern Poland) were analyzed and classified. Representative fractures are relatively thin (0.1 mm), flat and completely sealed with calcite. Next, the morphology evolution of reactivated natural fractures treated with low-pH fluids has been simulated numerically under various operating conditions. Depth-averaged equations for fracture flow and reactant transport has been solved by finite-difference method coupled with sparse-matrix solver. Transport-limited dissolution has been considered, which corresponds to the treatment with strong acids, such as HCl. Calcite coating in reactivated natural fractures dissolves in a highly non-homogeneous manner - a positive feedback between fluid transport and calcite dissolution leads to the spontaneous formation of wormhole-like patterns, in which most of the flow is focused. The wormholes carry reactive fluids deeper inside the system, which dramatically increases the range of the treatment. Non-uniformity of the dissolution patterns provides a way of retaining the fracture permeability even in the absence of the proppant, since the less dissolved regions will act as supports to keep more dissolved regions open. Evolution of fracture morphology is shown to depend strongly on the thickness of calcite layer - the thicker the coating the more pronounced wormholes are observed. However the interaction between

  15. Connections between Frontier Markets

    Directory of Open Access Journals (Sweden)

    Eliza-Olivia Lungu

    2013-06-01

    Full Text Available The global financial system presents a high degree of connectivity and the network theory provides the natural framework for visualizing the structure of it connections. I analyse the financial links established between the frontier markets and how these links evolve over a 10 years period (2001 - 2011. I identify patterns in the network looking both at the node specific statistics (degree, strength and clustering coefficient and at the aggregated network statistics (network density and network asymmetry index.

  16. Fracture of nanoporous organosilicate thin films

    Science.gov (United States)

    Gage, David Maxwell

    Nanoporous organosilicate thin films are attractive candidates for a number of emerging technologies, ranging from biotechnology to optics and microelectronics. However, integration of these materials is challenged by their fragile nature and susceptibility to mechanical failure. Debonding and cohesive cracking of the organosilicate film are principal concerns that threaten the reliability and yield of device structures. Despite the intense interest in these materials, there is currently a need for greater understanding of the relationship between glass structure and thermomechanical integrity. The objective of this research was to investigate strategies for improving mechanical performance through variations in film chemistry, process conditions, and pore morphology. Several approaches to effecting improvements in elastic and fracture properties were examined in depth, including post-deposition curing, molecular reinforcement using hydrocarbon network groups, and manipulation of pore size and architecture. Detailed structural characterization was employed along with quantitative fracture mechanics based testing methods. It was shown that ultra-violet irradiation and electron bombardment post-deposition treatments can significantly impact glass structure in ways that cannot be achieved through thermal activation alone. Both techniques demonstrated high porogen removal efficiency and enhanced the glass matrix through increased network connectivity and local bond rearrangements. The increases in network connectivity were achieved predominantly through the replacement of terminal groups, particularly methyl and silanol groups, with Si-O network bonds. Nuclear magnetic resonance spectroscopy was shown to be a powerful and quantitative method for gaining new insight into the underlying cure reactions and mechanisms. It was demonstrated that curing leads to significant progressive enhancement of elastic modulus and adhesive fracture energies due to increased network bond

  17. Banana Fibers – Variability and Fracture Behaviour

    Directory of Open Access Journals (Sweden)

    Samrat Mukhopadhyay, Ph.D.

    2008-06-01

    Full Text Available Banana fibers obtained from the stem of banana plant (Musa sapientum have been characterised for their diameter variability and their mechanical properties, with a stress on fracture morphology. The nature of representative stress strain curves and fracture at different strain rates have been analysed through SEM.

  18. Fracture characterization from formation microlmager data

    NARCIS (Netherlands)

    Ponziani, M.; Slob, E.C.; Luthi, S.M.; Bloemenkamp, R.F.; Le Nir, I.

    2013-01-01

    The Formation MicroImager (mark of Schlumberger) is an electric imaging tool that produces electrical scans of the borehole walls. These measurements provide useful information on the fracture aperture of naturally fractured reservoirs. In this paper, we present a laboratory set-up that was realized

  19. Hydrofracture Modeling Using Discrete Fracture Network in Barnett Shale

    Science.gov (United States)

    Yaghoubi, A.; Zoback, M. D.

    2012-12-01

    Shale gas has become an important source of unconventional reservoir in the united state over the past decade. Since the shale gas formations are impermeable, hydraulic fracturing from vertical and horizontal well are commonly approach to extract natural gas deposit from these unconventional sources. Hydraulic fracturing has been a successful and relatively inexpensive stimulation method for stimulation and enhances hydrocarbon recovery. Multistage hydro fracturing treatments in horizontal well creates a large stimulated reservoir volume. However, modeling hydraulic fracturing requires to prior knowledge of natural fracture network. This problem can be deal with Discrete Fracture network modeling. The objective of this study is first to model discrete fracture network and then simulate hydro-fracturing in five horizontal well of a case study in Barnett shale gas reservoir. In the case study, five horizontal wells have been drilled in Barnett shale gas reservoir in which each of them has 10 stages of hydro-fracturing stimulation. Of all five wells, just well C has a full comprehensive logging data. Fracture date detected using FMI image log of well C for building DFN model are associated with different sources of uncertainty; orientation, density and length. After building reservoir geomechanics model and detecting natural fracture form image log from well C, DFN model has built based on fracture parameters, orientation, intensity, shape size and permeability detected from image log and core data. Modeling hydrofractuing in five wells are consistent with critically stressed-fracture and micro-seismic events.

  20. Discrete Fracture Network Models for Risk Assessment of Carbon Sequestration in Coal

    Energy Technology Data Exchange (ETDEWEB)

    Jack Pashin; Guohai Jin; Chunmiao Zheng; Song Chen; Marcella McIntyre

    2008-07-01

    A software package called DFNModeler has been developed to assess the potential risks associated with carbon sequestration in coal. Natural fractures provide the principal conduits for fluid flow in coal-bearing strata, and these fractures present the most tangible risks for the leakage of injected carbon dioxide. The objectives of this study were to develop discrete fracture network (DFN) modeling tools for risk assessment and to use these tools to assess risks in the Black Warrior Basin of Alabama, where coal-bearing strata have high potential for carbon sequestration and enhanced coalbed methane recovery. DFNModeler provides a user-friendly interface for the construction, visualization, and analysis of DFN models. DFNModeler employs an OpenGL graphics engine that enables real-time manipulation of DFN models. Analytical capabilities in DFNModeler include display of structural and hydrologic parameters, compartmentalization analysis, and fluid pathways analysis. DFN models can be exported to third-party software packages for flow modeling. DFN models were constructed to simulate fracturing in coal-bearing strata of the upper Pottsville Formation in the Black Warrior Basin. Outcrops and wireline cores were used to characterize fracture systems, which include joint systems, cleat systems, and fault-related shear fractures. DFN models were constructed to simulate jointing, cleating, faulting, and hydraulic fracturing. Analysis of DFN models indicates that strata-bound jointing compartmentalizes the Pottsville hydrologic system and helps protect shallow aquifers from injection operations at reservoir depth. Analysis of fault zones, however, suggests that faulting can facilitate cross-formational flow. For this reason, faults should be avoided when siting injection wells. DFN-based flow models constructed in TOUGH2 indicate that fracture aperture and connectivity are critical variables affecting the leakage of injected CO{sub 2} from coal. Highly transmissive joints

  1. Prediction of Flow and Solute Transport in Fractured Media: Comparison of Metrics to Describe Effects of Rough Surfaces

    Science.gov (United States)

    Slottke, D.; Ketcham, R. A.; Sharp, J. M.

    2008-05-01

    Fractures dominate fluid flow and transport of solutes when they are open and connected. The prediction of flow through fractured media has implications for development of water resources, petroleum reservoir exploitation, contamination and remediation assessment, and site evaluation for waste repositories. Assessing the impact of surface roughness on fluid flow and solute transport through fractured media from samples on the order of 100 cm2 assumes the existence of a relationship between fracture morphology and discharge that is scale invariant or at least smoothly transformable. Although some studies assume that the length scale at which surface roughness significantly contributes to the discharge through a fracture falls within the size of a typical hand sample, there is a dearth of empirical data supporting an extension of the relationships found at small scales to larger samples. Furthermore, an appropriate metric to describe a fracture volume accurately must be chosen. We compile data from physical flow tests and numerical modeling of two discrete natural fractures of different scales in rhyolitc tuff. The University of Texas HRXCT facility provided computed tomography representations of the fractures that allow analysis of surface roughness and aperture statistics at 0.25mm grid resolution, which form the basis for transmissivity field inputs to numerical models. We show that although a small (10cm2) representative surface can describe roughness, aperture fields are not so well behaved. We compare physical flow test results, modeled flow, and analytical solutions of the cubic law using various methods of assigning a meaningful aperture to illustrate the challenges of accurate modeling of fracture flow without a priori flow information. While a geometric mean aperture of the entire aperture field closely approximates the hydraulic aperture, an arbitrary profile mean aperture has little utility for predictive purposes.

  2. A Spatial Clustering Approach for Stochastic Fracture Network Modelling

    Science.gov (United States)

    Seifollahi, S.; Dowd, P. A.; Xu, C.; Fadakar, A. Y.

    2014-07-01

    Fracture network modelling plays an important role in many application areas in which the behaviour of a rock mass is of interest. These areas include mining, civil, petroleum, water and environmental engineering and geothermal systems modelling. The aim is to model the fractured rock to assess fluid flow or the stability of rock blocks. One important step in fracture network modelling is to estimate the number of fractures and the properties of individual fractures such as their size and orientation. Due to the lack of data and the complexity of the problem, there are significant uncertainties associated with fracture network modelling in practice. Our primary interest is the modelling of fracture networks in geothermal systems and, in this paper, we propose a general stochastic approach to fracture network modelling for this application. We focus on using the seismic point cloud detected during the fracture stimulation of a hot dry rock reservoir to create an enhanced geothermal system; these seismic points are the conditioning data in the modelling process. The seismic points can be used to estimate the geographical extent of the reservoir, the amount of fracturing and the detailed geometries of fractures within the reservoir. The objective is to determine a fracture model from the conditioning data by minimizing the sum of the distances of the points from the fitted fracture model. Fractures are represented as line segments connecting two points in two-dimensional applications or as ellipses in three-dimensional (3D) cases. The novelty of our model is twofold: (1) it comprises a comprehensive fracture modification scheme based on simulated annealing and (2) it introduces new spatial approaches, a goodness-of-fit measure for the fitted fracture model, a measure for fracture similarity and a clustering technique for proposing a locally optimal solution for fracture parameters. We use a simulated dataset to demonstrate the application of the proposed approach

  3. About Connections

    Directory of Open Access Journals (Sweden)

    Kathleen S Rockland

    2015-05-01

    Full Text Available Despite the attention attracted by connectomics, one can lose sight of the very real questions concerning What are connections? In the neuroimaging community, structural connectivity is ground truth and underlying constraint on functional or effective connectivity. It is referenced to underlying anatomy; but, as increasingly remarked, there is a large gap between the wealth of human brain mapping and the relatively scant data on actual anatomical connectivity. Moreover, connections have typically been discussed as pairwise, point x projecting to point y (or: to points y and z, or more recently, in graph theoretical terms, as nodes or regions and the interconnecting edges. This is a convenient shorthand, but tends not to capture the richness and nuance of basic anatomical properties as identified in the classic tradition of tracer studies. The present short review accordingly revisits connectional weights, heterogeneity, reciprocity, topography, and hierarchical organization, drawing on concrete examples. The emphasis is on presynaptic long-distance connections, motivated by the intention to probe current assumptions and promote discussions about further progress and synthesis.

  4. Growth Plate Fractures

    Science.gov (United States)

    ... the most widely used by doctors is the Salter-Harris system, described below. Type I Fractures These ... incidence of growth plate fractures peaks in adolescence. Salter-Harris classification of growth plate fractures. AAOS does ...

  5. Sport-related maxillofacial fractures

    NARCIS (Netherlands)

    Ruslin, M.; Boffano, P.; ten Brincke, Y.J.D.; Forouzanfar, T.; Brand, H.S.

    2016-01-01

    Sports and exercise are important causes of maxillofacial injuries. Different types of sports might differ in frequency and type of fractures. The aim of the present study was to explore the possible relation between the types of sport practiced and the frequency and nature of the facial bone fractu

  6. Sport-related maxillofacial fractures

    NARCIS (Netherlands)

    Ruslin, M.; Boffano, P.; ten Brincke, Y.J.D.; Forouzanfar, T.; Brand, H.S.

    2016-01-01

    Sports and exercise are important causes of maxillofacial injuries. Different types of sports might differ in frequency and type of fractures. The aim of the present study was to explore the possible relation between the types of sport practiced and the frequency and nature of the facial bone

  7. Contribution to the tectonic characterization of fractured reservoirs, I: photo-elasticimetric modelling of the stress perturbations near faults and the associated fracture network: application to oil reserves, II mechanisms for the 3D joint organization in a natural reservoir analogue (flat-lying Devonian Old Red Sandstones of Caitness in North Scotland); Contribution a la caracterisation tectonique des reservoirs fractures, I: modelisation photoelecticimetrique des perturbations de contrainte au voisinage des failles et de la fracturation associee: application petroliere, II: mecanismes de developpement en 3D des diaclases dans un analogue de reservoir, le Devonien tabulaire du caithness (Ecosse)

    Energy Technology Data Exchange (ETDEWEB)

    Auzias, V.

    1995-10-27

    In order to understand joint network organisation in oil reservoirs, as a first step we have adapted to technique (the photo-elasticimetry) to study stress fields in 2D. This method allows to determine the principal stress trajectories near faults, as well as the associated joint network organisation. Natural joint networks perturbed near faults are modeled and the parameters that control stress perturbation are proposed. With the aim of extrapolating joint data from a well to the entire reservoir our modelling is based on both 3 D seismic data and local joint data. The second part of our research was dedicated to studying joint propagation mechanisms in a natural reservoir analogue (flat-lying Devonian Old Red Sandstones of Caitness in North Scotland). Several exposure observation at different scales and in 3D (horizontal and cliff sections) allow to reconstitute the fracturing geometry from centimeter to kilometer scale and to link these to the regional tectonic history. This study shows that it is possible to differentiate three types of joints major joints, `classic` joints and micro-joints, each with different vertical persistence. New concepts on the 3D joint organisation have been deduced from field quantitative data, which can be applied to reservoir fracture modeling. In particular the non-coexistence phenomenon in a single bed of two regional joint sets with close strikes. Some joint development mechanisms are discussed: interaction between joints and sedimentary interfaces, joint distribution near faults, origin of en echelon arrays associated with joints. (author) 142 refs.

  8. Chopart fractures.

    Science.gov (United States)

    Klaue, Kaj

    2004-09-01

    The Chopart articular space was described by François Chopart (1743-1795) as a practical space for amputations in cases of distal foot necrosis. It corresponds to the limit between the anatomical hind-foot and the mid-foot. The bones involved are the talus and the calcaneus proximally, and the navicular and the cuboid distally. This space thus holds two functionally distinct entities, the anterior part of the coxa pedis (an essential functional joint) and the calcaneo-cuboidal joint,which can be considered to be an "adaptive joint" within a normal foot. Trauma to this region may cause fractures and/or dislocations and, in high energy trauma,compartment syndromes. Principles of treatment are immediate reduction of dislocations and realignment of the medial and lateral column of the foot in length and orientation. Open reduction and internal fixation of talus and navicular fractures are often indicated to restore the "coxa pedis". Open reconstruction or fusion in correct length of the calcaneo-cuboidal joint is occasionally indicated. Salvage procedures in malunions include navicular osteotomies and calcaneo-cuboidal bone block fusions. Treatment of joint destructions, especially involving the talo-navicular joint, include triple arthrodesis.

  9. HR Connect

    Data.gov (United States)

    US Agency for International Development — HR Connect is the USAID HR personnel system which allows HR professionals to process HR actions related to employee's personal and position information. This system...

  10. Fractures of the distal radius (Colles' fracture)

    National Research Council Canada - National Science Library

    João Carlos Belloti; João Baptista Gomes dos Santos; Álvaro Nagib Atallah; Walter Manna Albertoni; Flavio Faloppa

    2007-01-01

    CONTEXT AND OBJECTIVE: Although Colles' fracture is a common clinical situation for the orthopedist, we did not find any information in the literature that would allow safe decision-making on the best treatment for each fracture type...

  11. Etat de l'art en fracturation hydraulique State-Of-The-Art in Hydraulic Fracturing

    Directory of Open Access Journals (Sweden)

    Bouteca M.

    2006-11-01

    Full Text Available Cet article est un abrégé des connaissances de base sur la mécanique de la fracturation hydraulique (éléments de mécanique de la rupture, pression de fracturation et pression de fermeture, sur l'avancement actuel des travaux de modélisation de la propagation de fracture classés par type d'approche mécanique (bidimensionnelle, pseudotridimensionnelle, tridimensionnelle et par méthode de résolution (analytique, numérique, sur les propriétés des fluides de fracturation et des agents de soutènement. Deux chapitres à caractère plus pratique sont consacrés à la préparation et à la mise en oeuvre de la fracturation hydraulique ainsi qu'à l'évaluation des résultats de la fracturation hydraulique en termes de perméabilité, dimensions et direction de fracture. This article is an abridged review of basic knowledge about the mechanics of hydraulic fracturing (fracture mechanics, fracturing pressure and closure pressure, about recent advances in the modeling of fracture propagation classified by type of mechanical approach (two-dimensional, pseudo-three-dimensional, three-dimensional and by method of solution (analytic, numeric, and about the properties of fracturing fluids and propping agents. Two chapters having a more practical nature are devoted to the preparation and implementation of hydraulic fracturing as well as to the evaluation of hydraulic-fracturing results in terms of permeability and fracture sizes and direction.

  12. Technology and Internet Connections.

    Science.gov (United States)

    Allen, Denise; Lindroth, Linda

    1996-01-01

    Suggests that teachers can use computer software and Internet connections to enhance curriculum and capitalize student's natural interest in sports and sports figures. Provides a list of activities that students can do in relation to the Olympic games and gives information on how technology can assist in such activities. Appropriate Internet…

  13. Characterizing fractures and shear zones in crystalline rock using anisotropic seismic inversion and GPR imaging

    Science.gov (United States)

    Doetsch, Joseph; Krietsch, Hannes; Lajaunie, Myriam; Jordi, Claudio; Gischig, Valentin; Schmelzbach, Cedric; Maurer, Hansrudi

    2017-04-01

    Understanding the natural or artificially created hydraulic conductivity of a rock mass is critical for the successful exploitation of enhanced geothermal systems (EGS). The hydraulic response of fractured crystalline rock is largely governed by the spatial organization of permeable fractures. Defining the 3D geometry of these fractures and their connectivity is extremely challenging, because fractures can only be observed directly at their intersections with tunnels or boreholes. In the framework of an in-situ stimulation experiment at the Grimsel Test Site, a detailed rock mass characterization was carried out, combining geological and geophysical methods. While geological observations from tunnel mapping, core- and geophysical borehole-logging are reliable, the obtained data could just be interpolated between tunnels and boreholes. The geophysical surveys, including ground-penetration radar (GPR) imaging and tunnel-tunnel seismic tomography were able to image shear and fracture zones throughout the experimental volume. Clear GPR reflections up to a distance of 30 m from the tunnels allow to define the geometry of tunnel-mapped shear zones in the center of the experimental volume. Anisotropic traveltime inversion of tunnel-tunnel seismic data reveals fracture zones as low velocity zones and ductile shear zones as areas of increased seismic anisotropy. It is thus possible to characterize both type and geometry of shear and fracture zones, which is important for the planned rock stimulation. Combining the GPR and seismic results with the geological information, the geological model could be significantly improved, demonstrating the potential to characterize even subtle geological features in 3D.

  14. 煤层气压裂技术研究%Study of Fracturing Technology

    Institute of Scientific and Technical Information of China (English)

    刘光耀; 赵涵; 王博; 石美; 陈晓丽

    2011-01-01

    Coalbed methane(CBM) is a kind of self-generating and self-preserving,unconventional natural gas which stores in the coal seams and its surrounding rocks.Development and mining of coalbed methane can not only relieve pressure on energy supply but also protect the environment,and make sure the production safety,which are all of great significance.Fracturing of CBM wells can connect bore and natural fracture system together more effectively,avoid formation damage near the wellbore,and increase the speed of drainage.This paper begins with the definition,necessity of hydraulic fracture method,then introduces the hydraulic fracture characteristic,and at last points out the existing problems.%煤层气与常规天然气有较大差异,采用压裂施工可达到煤层气开发的理想效果。根据煤层气的特性,在施工中应注意压裂液、煤粉、压实性等因素所造成的伤害。

  15. Profile and procedures for fractures among 1323 fracture patients from the 2010 Yushu earthquake, China.

    Science.gov (United States)

    Kang, Peng; Tang, Bihan; Liu, Yuan; Liu, Xu; Shen, Yan; Liu, Zhipeng; Yang, Hongyang; Zhang, Lulu

    2016-11-01

    The injuries caused by earthquakes are often complex and of various patterns. Our study included all fracture inpatients from the Yushu earthquake (1323 in total), to learn more about the incidence and distribution of fractures during earthquakes. A retrospective study of the clinical characteristics of hospitalized fracture patients after the 2010 Yushu earthquake was conducted from December 20 to 25, 2010.We reviewed medical records of hospitalized patients who had been evacuated from the Yushu earthquake area between April 14 and June 15, 2010, from 57 hospitals, and also reviewed more than 100 documents assembled from daily medical rescue and disease prevention reports submitted by the frontline rescue organizations. In total, 78.0% of fracture patients were admitted to the hospital within 3 days after the earthquake. There were 1323 patients who presented with 1539 fractures. The most common fracture occurred in the lower limbs, followed by spinal, pelvic, and shoulder-upper limb fractures. The end of the thoracic vertebra and the lumbar vertebra were the high-risk sites for vertebral fractures. A total of 38 patients became paraplegic. A 2-level spatial clustering was detected among the 193 patients presenting with 2 fractures. Analysis profiles of the injuries and clinical features of patients with earthquake-related fractures will positively impact rescue efforts and the treatment of fracture injuries caused by possible future natural disasters. We should assemble orthopedic-related medications and surgical equipment, and allocate them promptly after a major earthquake. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. Positive approach: Implications for the relation between number theory and geometry, including connection to Santilli mathematics, from Fibonacci reconstitution of natural numbers and of prime numbers

    Energy Technology Data Exchange (ETDEWEB)

    Johansen, Stein E., E-mail: stein.johansen@svt.ntnu.no [Institute for Basic Research, Division of Physics, Palm Harbor, Florida, USA and Norwegian University of Science and Technology, Department of Social Anthropology, Trondheim (Norway)

    2014-12-10

    The paper recapitulates some key elements in previously published results concerning exact and complete reconstitution of the field of natural numbers, both as ordinal and as cardinal numbers, from systematic unfoldment of the Fibonacci algorithm. By this natural numbers emerge as Fibonacci 'atoms' and 'molecules' consistent with the notion of Zeckendorf sums. Here, the sub-set of prime numbers appears not as the primary numbers, but as an epistructure from a deeper Fibonacci constitution, and is thus targeted from a 'positive approach'. In the Fibonacci reconstitution of number theory natural numbers show a double geometrical aspect: partly as extension in space and partly as position in a successive structuring of space. More specifically, the natural numbers are shown to be distributed by a concise 5:3 code structured from the Fibonacci algorithm via Pascal's triangle. The paper discusses possible implications for the more general relation between number theory and geometry, as well as more specifically in relation to hadronic mathematics, initiated by R.M. Santilli, and also briefly to some other recent science linking number theory more directly to geometry and natural systems.

  17. Fractures and rock mechanics, Phase 2

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-03-01

    Knowledge of fracture occurrence and orientation in chalk is important for optimum field development planning and evaluation of well-bore stability. The combined geological and geotechnical studies carried out under the EFP-96 and EFP-98 programmes have investigated the influence of fractures on rock mechanics properties for chalk. Data for quantifying the effect of natural fractures in chalk have been supplied by triaxial testing in normal scale and large scale on samples from three chalk types, namely from Valhall Tor and Tyra Maastrichtian and an outcrop locality at Hillerslev. >From the latter locality special big cylindrical specimens were sampled for the large scale triaxial testing (500x500 mm) in order to get at true representation of the natural fracturing in the Hillerslev chalk. By comparing test results from normal scale to large scale on fractured and non fractured specimens it was found that the stiffness of the chalk is dependent on scale while the shear strength generally seems to depend on fractures and not on scale. Furthermore the studies revealed, that fractures have a significant reducing effect on the shear strength, that characterisation by the Geological Strength Index, GSI, on fractured test specimens igve a very good prediction of shear, that shear failure and yield surface characteristics for fractued and intact chalk can be provided using GSI, that up-scaling influence the elastic deformation properties in the low stress regime and that fractures influence the compressibility in the elastic stress regime, but not in the plastic stress regime. Finally, the practical application of some of the results on reservoir chalk has been addressed, especially the up-scaling of strength and deformation properties from normal scale tests to reservoir conditions. The up-scaling laws are relevant for borehole stability problems but not for compaction. Generally, the observations in the study are relevant for quantifying the effect of fracturing and

  18. Characterizing Fracture Spatial Patterns by Using Semivariograms

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Semivariogram is applied to fracture data obtained from detailed scanline surveys of nine field sites in western New York, USA in order to investigate the spatial patterns of natural fractures. The length of the scanline is up to 36 m. How both fracture spacing and fracture length vary with distance is determined through semivariogram calculations. In this study, the authors developed a FORTRAN program to resample the fracture data from the scanline survey. By calculating experimental semivariogram, the authors found five different types of spatial patterns that can be described by linear, spherical, reversed spherical, polynomial I (for a0) models, of which the last three are newly proposed in this study. The well-structured semivariograms of fracture spacing and length indicate that both the location of the fractures and the length distribution within their structure domains are not random. The results of this study also suggest that semivariograms can provide useful information in terms of spatial correlation distance for fracture location and fracture length. These semivariograms can also be utilized to design more efficient sampling schemes for further surveys, as well as to define the limits of highly probable extrapolation of a structure domain.

  19. Fracture channel waves

    Science.gov (United States)

    Nihei, Kurt T.; Yi, Weidong; Myer, Larry R.; Cook, Neville G. W.; Schoenberg, Michael

    1999-03-01

    The properties of guided waves which propagate between two parallel fractures are examined. Plane wave analysis is used to obtain a dispersion equation for the velocities of fracture channel waves. Analysis of this equation demonstrates that parallel fractures form an elastic waveguide that supports two symmetric and two antisymmetric dispersive Rayleigh channel waves, each with particle motions and velocities that are sensitive to the normal and tangential stiffnesses of the fractures. These fracture channel waves degenerate to shear waves when the fracture stiffnesses are large, to Rayleigh waves and Rayleigh-Lamb plate waves when the fracture stiffnesses are low, and to fracture interface waves when the fractures are either very closely spaced or widely separated. For intermediate fracture stiffnesses typical of fractured rock masses, fracture channel waves are dispersive and exhibit moderate to strong localization of guided wave energy between the fractures. The existence of these waves is examined using laboratory acoustic measurements on a fractured marble plate. This experiment confirms the distinct particle motion of the fundamental antisymmetric fracture channel wave (A0 mode) and demonstrates the ease with which a fracture channel wave can be generated and detected.

  20. Traumatic thoracolumbar spine fractures

    NARCIS (Netherlands)

    J. Siebenga (Jan)

    2013-01-01

    textabstractTraumatic spinal fractures have the lowest functional outcomes and the lowest rates of return to work after injury of all major organ systems.1 This thesis will cover traumatic thoracolumbar spine fractures and not osteoporotic spine fractures because of the difference in fracture

  1. Fracture mechanics of PGX graphite

    Energy Technology Data Exchange (ETDEWEB)

    Ho, F.H.; Vollman, R.E.; Cull, A.D.

    1981-03-01

    Fracture mechanics tests were performed on grade PGX graphite. A compact tension specimen configuration which yields consistent values of the opening mode critical stress intensity factor K/sub IC/, was designed. For the calculation of the fracture toughness and crack growth rate the concept of the effective crack length is used. It corresponds to the crack length of a machined notched specimen with the same compliance. Fracture toughness testing was performed in two environments, air and helium, both at room temperature. The critical stress intensity factor, K/sub IC/, is calculated based on the maximum load and the effective crack length. The fatigue crack growth test was performed in air only. A break-in period was observed for the machined notch to develop into a naturally occurring crack path. Half of the fatigue life was spent in this period.

  2. Connected Traveler

    Energy Technology Data Exchange (ETDEWEB)

    2016-06-01

    The Connected Traveler framework seeks to boost the energy efficiency of personal travel and the overall transportation system by maximizing the accuracy of predicted traveler behavior in response to real-time feedback and incentives. It is anticipated that this approach will establish a feedback loop that 'learns' traveler preferences and customizes incentives to meet or exceed energy efficiency targets by empowering individual travelers with information needed to make energy-efficient choices and reducing the complexity required to validate transportation system energy savings. This handout provides an overview of NREL's Connected Traveler project, including graphics, milestones, and contact information.

  3. Assessment of fracture risk

    Energy Technology Data Exchange (ETDEWEB)

    Kanis, John A. [WHO Collaborating Centre for Metabolic Bone Diseases, University of Sheffield Medical School, Beech Hill Road, Sheffield S10 2RX (United Kingdom)], E-mail: w.j.pontefract@sheffield.ac.uk; Johansson, Helena; Oden, Anders [WHO Collaborating Centre for Metabolic Bone Diseases, University of Sheffield Medical School, Beech Hill Road, Sheffield S10 2RX (United Kingdom); McCloskey, Eugene V. [WHO Collaborating Centre for Metabolic Bone Diseases, University of Sheffield Medical School, Beech Hill Road, Sheffield S10 2RX (United Kingdom); Osteoporosis Centre, Northern General Hospital, Sheffield (United Kingdom)

    2009-09-15

    Fractures are a common complication of osteoporosis. Although osteoporosis is defined by bone mineral density at the femoral neck, other sites and validated techniques can be used for fracture prediction. Several clinical risk factors contribute to fracture risk independently of BMD. These include age, prior fragility fracture, smoking, excess alcohol, family history of hip fracture, rheumatoid arthritis and the use of oral glucocorticoids. These risk factors in conjunction with BMD can be integrated to provide estimates of fracture probability using the FRAX tool. Fracture probability rather than BMD alone can be used to fashion strategies for the assessment and treatment of osteoporosis.

  4. Optimal scaling in ductile fracture

    Science.gov (United States)

    Fokoua Djodom, Landry

    This work is concerned with the derivation of optimal scaling laws, in the sense of matching lower and upper bounds on the energy, for a solid undergoing ductile fracture. The specific problem considered concerns a material sample in the form of an infinite slab of finite thickness subjected to prescribed opening displacements on its two surfaces. The solid is assumed to obey deformation-theory of plasticity and, in order to further simplify the analysis, we assume isotropic rigid-plastic deformations with zero plastic spin. When hardening exponents are given values consistent with observation, the energy is found to exhibit sublinear growth. We regularize the energy through the addition of nonlocal energy terms of the strain-gradient plasticity type. This nonlocal regularization has the effect of introducing an intrinsic length scale into the energy. We also put forth a physical argument that identifies the intrinsic length and suggests a linear growth of the nonlocal energy. Under these assumptions, ductile fracture emerges as the net result of two competing effects: whereas the sublinear growth of the local energy promotes localization of deformation to failure planes, the nonlocal regularization stabilizes this process, thus resulting in an orderly progression towards failure and a well-defined specific fracture energy. The optimal scaling laws derived here show that ductile fracture results from localization of deformations to void sheets, and that it requires a well-defined energy per unit fracture area. In particular, fractal modes of fracture are ruled out under the assumptions of the analysis. The optimal scaling laws additionally show that ductile fracture is cohesive in nature, i.e., it obeys a well-defined relation between tractions and opening displacements. Finally, the scaling laws supply a link between micromechanical properties and macroscopic fracture properties. In particular, they reveal the relative roles that surface energy and microplasticity

  5. Fractal characterization of geological fractures in an exposed analog of a petroleum reservoir and its application to fluid flow models

    Science.gov (United States)

    Vásquez, A.; Tolson, G.

    2012-12-01

    The quantification of fracture systems is important to understand the phenomenon of fluid flow in naturally fractured petroleum reservoirs. In this work, we present a case of detailed analysis of filled fracture networks (veins) covering four orders of magnitude of scale. For our analysis we selected rocks of the El Doctor platform in the state of Querétaro, Central Mexico, which is an exposed analog of naturally fractured carbonate reservoir rocks common in the near-offshore oil fields in southeast Mexico. The fractal properties of one and two dimensional natural fracture patterns mapped on limestone outcrops, are present and compared to the results obtained in other studies at different scales. The fractal dimension of different fracture properties, such as spacing, thickness, spatial distribution, density, connectivity and length are investigated and measured using different methods. The principal fractal parameters obtained in this study include the cumulative-frequency exponent of spacing and thickness, box-counting dimension, correlation dimension and Lyapunov exponent in 1D analysis; whereas the 2D analysis included the cumulative-length exponent (fragmentation dimension), box-counting dimension, mass dimension (mid and intersection points of fractures), lacunarity and connectivity. In addition, we analyzed the orientation, density and intensity of the fracture arrays. The results of the 1D analysis indicate that the fracture spacing can be characterised using the parameters mentioned before, but the best fractal parameter to characterize the distribution and array of fractures is the Lyapunov exponent, because it's value (1.06-1.42) can differentiate between different types of array. The fractal dimension obtained for cumulative-frequency of the spacing, shows a power law with a negative exponent between -1.08 and -0.70. In the case of box-counting and correlation dimensions, the values of dimension were 0.30-0.68 and 0.40-0.63 respectively. With respect

  6. Experimental study on water seepage constitutive law of fracture in rock under 3D stress

    Institute of Scientific and Technical Information of China (English)

    赵阳升; 杨栋; 郑少河; 胡耀青

    1999-01-01

    The test method and test result of water seepage constitutive law of fracture in rock under 3D stress are introduced. A permeability coefficient formula including the coefficient of fracture connection, normal stiffness, 3D stress, initial width of fracture and Poisson ratio is presented based on the analysis of the test theory and its result.

  7. Fatigue damage of steam turbine shaft at asynchronous connections of turbine generator to electrical network

    Science.gov (United States)

    Bovsunovsky, A. P.

    2015-07-01

    The investigations of cracks growth in the fractured turbine rotors point out at theirs fatigue nature. The main reason of turbine shafts fatigue damage is theirs periodical startups which are typical for steam turbines. Each startup of a turbine is accompanied by the connection of turbine generator to electrical network. During the connection because of the phase shift between the vector of electromotive force of turbine generator and the vector of supply-line voltage the short-term but powerful reactive shaft torque arises. This torque causes torsional vibrations and fatigue damage of turbine shafts of different intensity. Based on the 3D finite element model of turbine shaft of the steam turbine K-200-130 and the mechanical properties of rotor steel there was estimated the fatigue damage of the shaft at its torsional vibrations arising as a result of connection of turbine generator to electric network.

  8. [Connective tissue and inflammation].

    Science.gov (United States)

    Jakab, Lajos

    2014-03-23

    The author summarizes the structure of the connective tissues, the increasing motion of the constituents, which determine the role in establishing the structure and function of that. The structure and function of the connective tissue are related to each other in the resting as well as inflammatory states. It is emphasized that cellular events in the connective tissue are part of the defence of the organism, the localisation of the damage and, if possible, the maintenance of restitutio ad integrum. The organism responds to damage with inflammation, the non specific immune response, as well as specific, adaptive immunity. These processes are located in the connective tissue. Sterile and pathogenic inflammation are relatively similar processes, but inevitable differences are present, too. Sialic acids and glycoproteins containing sialic acids have important roles, and the role of Siglecs is also highlighted. Also, similarities and differences in damages caused by pathogens and sterile agents are briefly summarized. In addition, the roles of adhesion molecules linked to each other, and the whole event of inflammatory processes are presented. When considering practical consequences it is stressed that the structure (building up) of the organism and the defending function of inflammation both have fundamental importance. Inflammation has a crucial role in maintaining the integrity and the unimpaired somato-psychological state of the organism. Thus, inflammation serves as a tool of organism identical with the natural immune response, inseparably connected with the specific, adaptive immune response. The main events of the inflammatory processes take place in the connective tissue.

  9. Review of Hydraulic Fracturing for Preconditioning in Cave Mining

    Science.gov (United States)

    He, Q.; Suorineni, F. T.; Oh, J.

    2016-12-01

    Hydraulic fracturing has been used in cave mining for preconditioning the orebody following its successful application in the oil and gas industries. In this paper, the state of the art of hydraulic fracturing as a preconditioning method in cave mining is presented. Procedures are provided on how to implement prescribed hydraulic fracturing by which effective preconditioning can be realized in any in situ stress condition. Preconditioning is effective in cave mining when an additional fracture set is introduced into the rock mass. Previous studies on cave mining hydraulic fracturing focused on field applications, hydraulic fracture growth measurement and the interaction between hydraulic fractures and natural fractures. The review in this paper reveals that the orientation of the current cave mining hydraulic fractures is dictated by and is perpendicular to the minimum in situ stress orientation. In some geotechnical conditions, these orientation-uncontrollable hydraulic fractures have limited preconditioning efficiency because they do not necessarily result in reduced fragmentation sizes and a blocky orebody through the introduction of an additional fracture set. This implies that if the minimum in situ stress orientation is vertical and favors the creation of horizontal hydraulic fractures, in a rock mass that is already dominated by horizontal joints, no additional fracture set is added to that rock mass to increase its blockiness to enable it cave. Therefore, two approaches that have the potential to create orientation-controllable hydraulic fractures in cave mining with the potential to introduce additional fracture set as desired are proposed to fill this gap. These approaches take advantage of directional hydraulic fracturing and the stress shadow effect, which can re-orientate the hydraulic fracture propagation trajectory against its theoretical predicted direction. Proppants are suggested to be introduced into the cave mining industry to enhance the

  10. Order-theoretical connectivity

    Directory of Open Access Journals (Sweden)

    T. A. Richmond

    1990-01-01

    Full Text Available Order-theoretically connected posets are introduced and applied to create the notion of T-connectivity in ordered topological spaces. As special cases T-connectivity contains classical connectivity, order-connectivity, and link-connectivity.

  11. Getting Connected

    Science.gov (United States)

    Larkin, Patrick

    2011-01-01

    That the world outside schools is changing faster than ever is old news. Unfortunately, that the world "inside" schools is changing at a glacial pace is even older news. As school leaders, principals have an important choice to make as they move into the second decade of the 21st century. School leaders have a moral obligation to connect and…

  12. Connecting dots

    DEFF Research Database (Denmark)

    Murakami, Kyoko; Jacobs, Rachel L.

    2017-01-01

    of connecting the dots of recalled moments of individual family members lives and is geared towards building a family’s shared future for posterity. Lastly, we consider a wider implication of family reminiscence in terms of human development. http://www.infoagepub.com/products/Memory-Practices-and-Learning...

  13. Learning Connections

    Science.gov (United States)

    Royer, Regina D.; Richards, Patricia O.

    2005-01-01

    In this edition of Learning Connections, the authors show how technology can enhance study of weather patterns, reading comprehension, real-world training, critical thinking, health education, and art criticism. The following sections are included: (1) Social Studies; (2) Language Arts; (3) Computer Science and ICT; (4) Art; and (5) Health.…

  14. MULTI-PHASE FRACTURE-MATRIX INTERACTIONS UNDER STRESS CHANGES

    Energy Technology Data Exchange (ETDEWEB)

    A.S. Grader; D. Elsworth; P.M. Halleck; F. Alvarado; A. Alajmi; Z. Karpyn; N. Mohammed; S. Al-Enezi

    2005-06-15

    The main objectives of this project are to quantify the changes in fracture porosity and multiphase transport properties as a function of confining stress. These changes will be integrated into conceptual and numerical models that will improve our ability to predict and optimize fluid transport in fractured system. This report details our progress on: (a) developing the direct experimental measurements of fracture aperture and topology and fluid occupancy using high-resolution x-ray micro-tomography, (b) quantifying the effect of confining stress on the distribution of fracture aperture, and (c) characterization of shear fractures and their impact on multi-phase flow. The three-dimensional surface that describes the large-scale structure of the fracture in the porous medium can be determined using x-ray micro-tomography with significant accuracy. Several fractures have been scanned and the fracture aperture maps have been extracted. The success of the mapping of fracture aperture was followed by measuring the occupancy of the fracture by two immiscible phases, water and decane, and water and kerosene. The distribution of fracture aperture depends on the effective confining stress on the nature of the rock and the type and distribution of the asperities that keep the fracture open. Fracture apertures at different confining stresses were obtained by micro-tomography covering a range of about two thousand psig. Initial analysis of the data shows a significant aperture closure with increase in effective confining stress. Visual descriptions of the process are shown in the report while detailed analysis of the behavior of the distribution of fracture aperture is in progress. Both extensional and shear fractures are being considered. The initial multi-phase flow tests were done in extensional fractures. Several rock samples with induced shear fracture are being studies, and some of the new results are presented in this report. These samples are being scanned in order to

  15. Dynamic model of normal behavior of rock fractures

    Institute of Scientific and Technical Information of China (English)

    YANG Wen-yi; KONG Guang-ya; CAI Jun-gang

    2005-01-01

    Based on laboratory tests of artificial fractures in mortar material, established the dynamic constitutive model of normal behaviour of rock fracture,. The tests were systematically conducted under quasi-static and dynamic monotonic loading conditions. The fractures were of different numbers of asperities in contact and were subsequently of different initial contact areas, which imitated the natural rock fractures. The rate of compressive load applied normal to the fractures covers a wide range from 10-1 MPa/s (quasi-static) up to 103 MPa/s (highly dynamic). The normal stress-closure responses of fractures were measured for different loading rates. Based on the stress-closure relation curves measured, a nonlinear (hyperbolic) dynamic model of fracture, normal behaviour, termed as dynamic BB model, was proposed, which was modified from the existing BB model of static normal behaviour of fractures by taking into account the effect of loading rate.

  16. Theoretical and Practical Approach of Connecting the Ecotourist Offer of the Special Nature Reserve of Zasavica (Serbia with the Tourist Offer of the Surrounding Village Settlements

    Directory of Open Access Journals (Sweden)

    Dragan Dolinaj

    2009-06-01

    Full Text Available Pannonian basin was once covered by vast alluvial plains with patches of marsh, swamp, pan and prairie. With Holocene changes in climate, marshes have withdrawn and in the last couple hundreds of years they were pushed out by developing agricultural areas. The Nature Reserve Zasavica keeps the remains of former marshes and swamps on the territory of Vojvodina. One of the ways for providing necessary financial support for the reserve protection is development of ecotourist activities in the Zasavica region. Its biodiversity and numerous endangered species (Umbra krameri, Nymphaca alba, Numphar luteum, Stratiotes aloides, Acorus calamus, Buteo butes, Haliateetus albicilla, Lutra lutra, Castor fiber... could be the basis for tourist valorization of the Reserve. It is also necessary to conduct analyses of the impact of tourism on endangered species and confirm sustainability of those activities. The lack of accommodation capacities could be supplemented by the development of the tourist offer of the nearby countryside. This way the village tourism would enrich its offer with visits to the nature reserve. Such tourism activities would contribute towards the development of local communities and the improvement of the standard of living. Since the villages and the reserve are already territorially intertwined, their further tourist cooperation would lead to knowledge transfer and local people would have a better understanding of the protection of the Special Nature Reserve Zasavica.

  17. [Periprosthetic Acetabulum Fractures].

    Science.gov (United States)

    Schreiner, A J; Stuby, F; de Zwart, P M; Ochs, B G

    2016-12-01

    In contrast to periprosthetic fractures of the femur, periprosthetic fractures of the acetabulum are rare complications - both primary fractures and fractures in revision surgery. This topic is largely under-reported in the literature; there are a few case reports and no long term results. Due to an increase in life expectancy, the level of patients' activity and the number of primary joint replacements, one has to expect a rise in periprosthetic complications in general and periprosthetic acetabular fractures in particular. This kind of fracture can be intra-, peri- or postoperative. Intraoperative fractures are especially associated with insertion of cementless press-fit acetabular components or revision surgery. Postoperative periprosthetic fractures of the acetabulum are usually related to osteolysis, for example, due to polyethylene wear. There are also traumatic fractures and fractures missed intraoperatively that lead to some kind of insufficiency fracture. Periprosthetic fractures of the acetabulum are treated conservatively if the implant is stable and the fracture is not dislocated. If surgery is needed, there are many possible different surgical techniques and challenging approaches. That is why periprosthetic fractures of the acetabulum should be treated by experts in pelvic surgery as well as revision arthroplasty and the features specific to the patient, fracture and prosthetic must always be considered. Georg Thieme Verlag KG Stuttgart · New York.

  18. Fracture propagation in sandstone and slate e Laboratory experiments, acoustic emissions and fracture mechanics

    Institute of Scientific and Technical Information of China (English)

    Ferdinand Stoeckhert; Michael Molenda; Sebastian Brenne; Michael Alber

    2015-01-01

    abstract Fracturing of highly anisotropic rocks is a problem often encountered in the stimulation of unconven-tional hydrocarbon or geothermal reservoirs by hydraulic fracturing. Fracture propagation in isotropic material is well understood but strictly isotropic rocks are rarely found in nature. This study aims at the examination of fracture initiation and propagation processes in a highly anisotropic rock, specifically slate. We performed a series of tensile fracturing laboratory experiments under uniaxial as well as triaxial loading. Cubic specimens with edge lengths of 150 mm and a central borehole with a diameter of 13 mm were prepared from Fredeburg slate. An experiment using the rather isotropic Bebertal sandstone as a rather isotropic rock was also performed for comparison. Tensile fractures were generated using the sleeve fracturing technique, in which a polymer tube placed inside the borehole is pressurized to generate tensile fractures emanating from the borehole. In the uniaxial test series, the loading was varied in order to observe the transition from strength-dominated fracture propagation at low loading mag-nitudes to stress-dominated fracture propagation at high loading magnitudes.

  19. FRACTURED PETROLEUM RESERVOIRS

    Energy Technology Data Exchange (ETDEWEB)

    Abbas Firoozabadi

    1999-06-11

    The four chapters that are described in this report cover a variety of subjects that not only give insight into the understanding of multiphase flow in fractured porous media, but they provide also major contribution towards the understanding of flow processes with in-situ phase formation. In the following, a summary of all the chapters will be provided. Chapter I addresses issues related to water injection in water-wet fractured porous media. There are two parts in this chapter. Part I covers extensive set of measurements for water injection in water-wet fractured porous media. Both single matrix block and multiple matrix blocks tests are covered. There are two major findings from these experiments: (1) co-current imbibition can be more efficient than counter-current imbibition due to lower residual oil saturation and higher oil mobility, and (2) tight fractured porous media can be more efficient than a permeable porous media when subjected to water injection. These findings are directly related to the type of tests one can perform in the laboratory and to decide on the fate of water injection in fractured reservoirs. Part II of Chapter I presents modeling of water injection in water-wet fractured media by modifying the Buckley-Leverett Theory. A major element of the new model is the multiplication of the transfer flux by the fractured saturation with a power of 1/2. This simple model can account for both co-current and counter-current imbibition and computationally it is very efficient. It can be orders of magnitude faster than a conventional dual-porosity model. Part II also presents the results of water injection tests in very tight rocks of some 0.01 md permeability. Oil recovery from water imbibition tests from such at tight rock can be as high as 25 percent. Chapter II discusses solution gas-drive for cold production from heavy-oil reservoirs. The impetus for this work is the study of new gas phase formation from in-situ process which can be significantly

  20. Imaging of vertebral fractures

    Directory of Open Access Journals (Sweden)

    Ananya Panda

    2014-01-01

    Full Text Available Vertebral fracture is a common clinical problem. Osteoporosis is the leading cause of non-traumatic vertebral fracture. Often, vertebral fractures are not clinically suspected due to nonspecific presentation and are overlooked during routine interpretation of radiologic investigations. Moreover, once detected, many a times the radiologist fails to convey to the clinician in a meaningful way. Hence, vertebral fractures are a constant cause of morbidity and mortality. Presence of vertebral fracture increases the chance of fracture in another vertebra and also increases the risk of subsequent hip fracture. Early detection can lead to immediate therapeutic intervention improving further the quality of life. So, in this review, we wish to present a comprehensive overview of vertebral fracture imaging along with an algorithm of evaluation of vertebral fractures.

  1. [Horizontal root fracture repaired by cementum--a case report].

    Science.gov (United States)

    Lin, K R; Kuo, J S

    1989-09-20

    Horizontal root fractures are rare among dental trauma. According to Dr. Andreasen's report there are four types of repairs after root fractures. They are 1. healing with calcified tissue; 2. interposition of connective tissue; 3. interposition of connective and bony tissue; 4. interposition of granulation tissue. This report presented a case of horizontal root fracture in a 27 years old female patient. The patient had a trauma in the front teeth about 15 years ago. Spontaneous healing occurred without dental treatment at that moment. However, symptoms appeared recently as a dento-alveolar abscess. Radiograph revealed a horizontal fracture at the middle third of the root portion of the left upper central incisor, and irregular hard tissue over the fractured area. Histologically, the main component of repair tissue is cementum.

  2. What Have We Learned About Fluid-Fracture Interaction in the Analog Aquifer/Reservoir at the Valley of Fire, Nevada?

    Science.gov (United States)

    Aydin, A.; Pollard, D. D.; Durlofsky, L.

    2007-12-01

    The Jurassic aeolian Aztec Sandstone in the Valley of Fire State Park, Nevada, provides an exceptional natural laboratory to observe fluid-fracture interaction. This presentation is a summary of our investigations over the past decade and addresses: 1) how various fundamental types of fractures interacted with paleo-fluids; and 2) what we have learned about the hydrologic bases for these interactions. The oldest failure structures in the sandstone are a result of deformation localization of both shear band and compaction band types. These structures represent significant porosity and permeability reduction with respect to the undeformed rock as determined from image analyses and lattice-Boltzmann flow simulations, as well as from modeling the paleo-fluid fronts. The simplest failure structures are opening mode fractures or joints which conducted fluids in a fashion close to the idealized parallel plate model with well organized roughness. Sheared-joints which form by slip along pre- existing joints are the simplest shear fracture with slip on the order of millimeters to centimeters. There is abundant evidence that shearing enhanced the conductivity of these fractures. The physical bases of this phenomenon are thought to be dilation associated with slip across rough surfaces and increasing connectivity by linkage through splay fractures. Large-scale shear fractures or faults are always multi-component structures including slip surfaces, fault rocks, and damage zones which are composed of the simpler failure structures referred to above. Due to this complexity, the interaction between fluids and faults shows a wide range of variation. These effects are demonstrated using observation, laboratory measurements as well as upscaled permeability models. We conclude that the Valley of Fire analog aquifer/reservoir displays excellent examples of fluid-fracture interactions with a wide range of diversity, controlled primarily by the failure modes, and that flow modeling at

  3. Fracture Criterion for Fracture Mechanics of Magnets

    Institute of Scientific and Technical Information of China (English)

    潘灏; 杨文涛

    2003-01-01

    The applicability and limitation of some fracture criteria in the fracture mechanics of magnets are studied.It is shown that the magnetic field intensity factor can be used as a fracture criterion when the crack in a magnet is only affected by a magnetic field. For some magnetostrictive materials in which the components of magnetostriction strain do not satisfy the compatibility equation of deformation, the stress intensity factor can no longer be effectively applicable as a fracture criterion when the crack in a magnet is affected by a magnetic field and mechanical loads simultaneously.

  4. Optimization of flow modeling in fractured media with discrete fracture network via percolation theory

    Science.gov (United States)

    Donado-Garzon, L. D.; Pardo, Y.

    2013-12-01

    Fractured media are very heterogeneous systems where occur complex physical and chemical processes to model. One of the possible approaches to conceptualize this type of massifs is the Discrete Fracture Network (DFN). Donado et al., modeled flow and transport in a granitic batholith based on this approach and found good fitting with hydraulic and tracer tests, but the computational cost was excessive due to a gigantic amount of elements to model. We present in this work a methodology based on percolation theory for reducing the number of elements and in consequence, to reduce the bandwidth of the conductance matrix and the execution time of each network. DFN poses as an excellent representation of all the set of fractures of the media, but not all the fractures of the media are part of the conductive network. Percolation theory is used to identify which nodes or fractures are not conductive, based on the occupation probability or percolation threshold. In a fractured system, connectivity determines the flow pattern in the fractured rock mass. This volume of fluid is driven through connection paths formed by the fractures, when the permeability of the rock is negligible compared to the fractures. In a population of distributed fractures, each of this that has no intersection with any connected fracture do not contribute to generate a flow field. This algorithm also permits us to erase these elements however they are water conducting and hence, refine even more the backbone of the network. We used 100 different generations of DFN that were optimized in this study using percolation theory. In each of the networks calibrate hydrodynamic parameters as hydraulic conductivity and specific storage coefficient, for each of the five families of fractures, yielding a total of 10 parameters to estimate, at each generation. Since the effects of the distribution of fault orientation changes the value of the percolation threshold, but not the universal laws of classical

  5. Meteorite Fractures and Scaling for Atmospheric Entry

    Science.gov (United States)

    Bryson, Kathryn L.; Ostrowski, Daniel R.

    2016-10-01

    We are attempting to understand the behavior of asteroids entering the atmosphere in order to help quantify the impact hazard. The strength of meteorites plays a critical role in determining the outcome of their impact events. Our objective is to scale fracture parameters in meteorites to their parent body.In this study over a thousand meteorite fragments in the Natural History Museums of Vienna and London (mostly hand-sized, some 40 or 50 cm across) were examined and fracture patterns in selected fragments were imaged. We identified six kinds of fracturing behavior. The density and length of the observed fractures were measured in hand specimens and thin sections. We assume that fracturing follows the Weibull distribution, where fractures are assumed to be randomly distributed through the target and the likelihood of encountering a fracture increases with distance. The images collected of the six fracture behaviors provide a two-dimensional view of the fractures. A relationship exists between the distributions of measured trace length and actual fracture size, where the slope of a log-log plot of trace length vs fracture density is proportional to α, the shape parameter. The value for α is unclear and a large range in α has been determined from light curve data. α can be used to scale strengths from the meteorite to the larger parent body.The majority of the meteorite fractures imaged displayed no particular sensitivity to meteorite texture. A value of α of 0.185 has been determined for a chondrite with a fracture pattern that shows no sensitivity to meteorite texture and has no point of origin. This study will continue to examine additional meteorites with similar fracture patterns along with the other 5 patterns to see if there is a correlation between fracture pattern and α. This may explain the variations in α determined from fireball data. Values of α will be used in models created by the Asteroid Threat Assessment Project to try to determine the

  6. Bonded-cell model for particle fracture

    OpenAIRE

    Nguyen, Duc-Hanh; Azéma, Émilien; Sornay, Philippe; Radjaï, Farhang

    2015-01-01

    International audience; Particle degradation and fracture play an important role in natural granular flows and in many applications of granular materials. We analyze the fracture properties of two-dimensional disklike particles modeled as aggregates of rigid cells bonded along their sides by a cohesive Mohr-Coulomb law and simulated by the contact dynamics method. We show that the compressive strength scales with tensile strength between cells but depends also on the friction coefficient and ...

  7. Pneumatic fracturing of low permeability media

    Energy Technology Data Exchange (ETDEWEB)

    Schuring, J.R. [New Jersey Institute of Technology, Newark, NJ (United States)

    1996-08-01

    Pneumatic fracturing of soils to enhance the removal and treatment of dense nonaqueous phase liquids is described. The process involves gas injection at a pressure exceeding the natural stresses and at a flow rate exceeding the permeability of the formation. The paper outlines geologic considerations, advantages and disadvantages, general technology considerations, low permeability media considerations, commercial availability, efficiency, and costs. Five case histories of remediation using pneumatic fracturing are briefly summarized. 11 refs., 2 figs., 1 tab.

  8. Qatar Connection

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Chinese oil conglomerates sign big contracts with the Gulf nation for liquefied natural gas to stem their deficit Two of China’s biggest oil companies inked major long-term deals on April 10 to buy liquefied natural gas(LNG) from Qatargas Operating Co. In the first deal,Qatargas and its part- ner,Shell Oil Corp.,agreed to sell 3 million tons of LNG annually to China National

  9. DISTRIBUTION PREDICTION AND EVALUATION OF NATURAL FRACTURES IN 2nd XU MEMBER GAS RESERVOIRS, XINCHANG ARE-A, WEST SICHUAN BASIN%川西新场地区须二气藏天然裂缝分布综合预测及评价(上)

    Institute of Scientific and Technical Information of China (English)

    毕海龙; 周文; 谢润成; 邓虎成

    2012-01-01

    Natural fractures with complex formation periods are important factors to affect the development capacity in the 2nd Xu Member in Xinchang area, west Sichuan basin. Based on the identification and statistic of natural fractures in field, cores and thin section, the characteristics of the nature fractures are concluded and summarized. According with different geological factors such as bed thickness, structural deformation, faults, lithology, physical properties et al. , it is analyzed that those control of the natural fractures and figure out the main controlling factors of the natural fractures. Under the premise of the natural fracture characteristics and the main controlling factors, by comparing the results of single factor fractures predicting and the results of single well interpreting and considering the main controlling factors of the 2nd Xu member in Xinchang area, a comprehensive evaluation factor of distribution predication of natural fractures is established. It is evaluated that the fractures distribution prediction results by the production performance data and the consistent rate of evaluation results is more than 80% and the results meet the requirements of the development and application of precision.%川西新场须二气藏天然裂缝发育,成因期次复杂,是影响开发产能的一个重要因素.这里通过对野外、岩心、薄片中天然裂缝的调查、鉴定及统计等工作,对天然裂缝的发育特征进行了归纳和总结;从岩层厚度、构造变形、断层、岩性、物性等不同地质因素,分析了其对天然裂缝发育的控制作用,并了解了天然裂缝发育的主要控制因素.在天然裂缝特征、主控因素认识的前提下,通过对比分析单一因素裂缝预测结果与单井裂缝解释结果的吻合率,确定了各因素的影响权值,并综合考虑主控因素建立了适合新场须二气藏天然裂缝分布预测的综合评价因子.通过生产动态资料对裂缝分布预

  10. 川西新场地区须二气藏天然裂缝分布综合预测及评价(下)%DISTRIBUTION PREDICTION AND EVALUATION OF NATURAL FRACTURES IN 2nd XUMEMBER GAS RESERVOIRS, XINCHANG AREA, WEST SICHUAN BASIN

    Institute of Scientific and Technical Information of China (English)

    毕海龙; 周文; 谢润成; 邓虎成

    2013-01-01

    川西新场须二气藏天然裂缝发育,成因期次复杂,是影响开发产能的一个重要因素.通过对野外岩心、薄片中天然裂缝的调查、鉴定及统计等工作,对天然裂缝的发育特征进行了归纳和总结;从岩层厚度、构造变形、断层、岩性、物性等不同地质因素,分析了其对天然裂缝发育的控制作用,并了解了天然裂缝发育的主要控制因素.在天然裂缝特征、主控因素认识的前提下,通过对比分析单一因素裂缝预测结果与单井裂缝解释结果的吻合率确定了各因素的影响权值,并综合考虑主控因素建立了适合新场须二气藏天然裂缝分布预测综合评价因子.通过生产动态资料对裂缝分布预测结果进行了评价,吻合率达到80%以上,预测结果满足了开发应用的精度要求.%Natural fractures with complex formation periods are important factors to affect the development capacity in The 2nd Xu member in Xinchang area, west Sichuan basin. Based on the survey, i-dentification and statistic of natural fractures in field, cores and thin section, the characteristics of the nature fractures are concluded and summarized. According with different geological factors such as bed thickness, structural deformation, faults, lithology, physical properties et al. to a-nalysis those control of the natural fractures and figure out the main controlling factors of the natural fractures. Under the premise of the natural fracture characteristics and the main controlling factors, by comparing the results of single factor fractures predicting and the results of single well interpreting and considering the main controlling factors of the 2nd Xu member in Xinchang area, a comprehensive evaluation factor of distribution predication of natural fractures is established. E-valuate the fractures distribution prediction results by the production performance data that the consistent rate of them is more than 80% and the results are to

  11. Fundamental Technical Elements of Freeze-fracture/Freeze-etch in Biological Electron Microscopy

    Science.gov (United States)

    Freeze-fracture/freeze-etch describes a process whereby specimens, typically biological or nanomaterial in nature, are frozen, fractured, and replicated to generate a carbon/platinum "cast" intended for examination by transmission electron microscopy. Specimens are subjected to u...

  12. Fundamental Technical Elements of Freeze-fracture/Freeze-etch in Biological Electron Microscopy

    Science.gov (United States)

    Freeze-fracture/freeze-etch describes a process whereby specimens, typically biological or nanomaterial in nature, are frozen, fractured, and replicated to generate a carbon/platinum "cast" intended for examination by transmission electron microscopy. Specimens are subjected to u...

  13. Tibia (Shinbone) Shaft Fractures

    Science.gov (United States)

    ... energy collisions, such as an automobile or motorcycle crash, are common causes of tibial sha fractures. In cases like these, the bone can be broken into several pieces (comminuted fracture). Sports injuries, such as a fall while skiing or running ...

  14. Fractures in anisotropic media

    Science.gov (United States)

    Shao, Siyi

    Rocks may be composed of layers and contain fracture sets that cause the hydraulic, mechanical and seismic properties of a rock to be anisotropic. Coexisting fractures and layers in rock give rise to competing mechanisms of anisotropy. For example: (1) at low fracture stiffness, apparent shear-wave anisotropy induced by matrix layering can be masked or enhanced by the presence of a fracture, depending on the fracture orientation with respect to layering, and (2) compressional-wave guided modes generated by parallel fractures can also mask the presence of matrix layerings for particular fracture orientations and fracture specific stiffness. This report focuses on two anisotropic sources that are widely encountered in rock engineering: fractures (mechanical discontinuity) and matrix layering (impedance discontinuity), by investigating: (1) matrix property characterization, i.e., to determine elastic constants in anisotropic solids, (2) interface wave behavior in single-fractured anisotropic media, (3) compressional wave guided modes in parallel-fractured anisotropic media (single fracture orientation) and (4) the elastic response of orthogonal fracture networks. Elastic constants of a medium are required to understand and quantify wave propagation in anisotropic media but are affected by fractures and matrix properties. Experimental observations and analytical analysis demonstrate that behaviors of both fracture interface waves and compressional-wave guided modes for fractures in anisotropic media, are affected by fracture specific stiffness (controlled by external stresses), signal frequency and relative orientation between layerings in the matrix and fractures. A fractured layered medium exhibits: (1) fracture-dominated anisotropy when the fractures are weakly coupled; (2) isotropic behavior when fractures delay waves that are usually fast in a layered medium; and (3) matrix-dominated anisotropy when the fractures are closed and no longer delay the signal. The

  15. Sprains, Strains and Fractures

    Science.gov (United States)

    ... Young Physicians Annual Scientific Meeting Webinars Careers in Podiatry APMA 2040 Student Profiles CPME REdRC Manage Your ... and fractures. Many fractures and sprains occur during sports. Football players are particularly vulnerable to foot and ...

  16. Hip fracture - discharge

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/patientinstructions/000168.htm Hip fracture - discharge To use the sharing features on this page, please enable JavaScript. Hip fracture surgery is done to repair a break in ...

  17. Hip fracture surgery

    Science.gov (United States)

    ... neck fracture repair; Trochanteric fracture repair; Hip pinning surgery; Osteoarthritis - hip ... You may receive general anesthesia for this surgery. This means you ... spinal anesthesia . With this kind of anesthesia, medicine is ...

  18. Periprosthetic acetabular fractures.

    Science.gov (United States)

    Benazzo, Francesco; Formagnana, Mario; Bargagliotti, Marco; Perticarini, Loris

    2015-10-01

    The aim of this article is to propose a diagnostic and therapeutic algorithm for the acetabular periprosthetic fractures. This article explores the current literature on the epidemiology, causes and classification of periprosthetic acetabular fractures. Integrating data with the experience of the authors, it offers a guide to diagnosis and possible therapeutic strategies. Intra-operative fractures can occur during rasping, reaming or implant impaction, and they must be treated immediately if the component(s) is (are) unstable. Post-operative fractures can be due to major trauma (acute fractures) or minor forces in bone osteolysis; it is possible to plan reconstruction and fixation according to fracture characteristics. Treatment choice depends upon fracture site and implant stability. Periprosthetic acetabular fractures are uncommon complications that can occur intra-operatively or post-operatively, and a reconstructive surgeon must be able to manage the procedure. Accurate planning and reconstruction implant are necessary to achieve good cup stability.

  19. Direct oblique sagittal CT of orbital wall fractures

    Energy Technology Data Exchange (ETDEWEB)

    Ball, J.B. Jr.

    1987-03-01

    Direct oblique sagittal CT was used to evaluate trauma to 77 orbits. Sixty-seven orbital wall fractures with intact orbital rims (36 floor, 22 medial wall, nine roof) were identified in 47 orbits. Since persistent diplopia and/or enophthalmos may warrant surgical repair of orbital floor fractures, optimal imaging should include an evaluation of extraocular muscle status, the nature and amount of displaced orbital contents, and an accurate definition of fracture margins. For orbital floor fractures, a combination of the direct oblique sagittal and direct coronal projections optimally displayed all fracture margins, the fracture's relationship to the inferior orbital rim and medial orbital wall, and the amount of displacement into the maxillary sinus. Inferior rectus muscle status with 36 floor fractures was best seen on the direct oblique sagittal projection in 30 fractures (83.3%) and was equally well seen on sagittal and coronal projections in two fractures (5.5%). Floor fractures were missed on 100% of axial, 5.5% of sagittal, and 0% of coronal projections. Since the direct oblique sagittal projection complements the direct coronal projection in evaluating orbital floor fractures, it should not be performed alone. A technical approach to the CT evaluation or orbital wall fractures is presented.

  20. Carbonate fracture stratigraphy: An integrated outcrop and 2D discrete element modelling study

    Science.gov (United States)

    Spence, Guy; Finch, Emma

    2013-04-01

    Constraining fracture stratigraphy is important as natural fractures control primary fluid flow in low matrix permeability naturally fractured carbonate hydrocarbon reservoirs. Away from the influence of folds and faults, stratigraphic controls are known to be the major control on fracture networks. The fracture stratigraphy of carbonate nodular-chert rhythmite successions are investigated using a Discrete Element Modelling (DEM) technique and validated against observations from outcrops. Comparisons are made to the naturally fractured carbonates of the Eocene Thebes Formation exposed in the west central Sinai of Egypt, which form reservoir rocks in the nearby East Ras Budran Field. DEM allows mechanical stratigraphy to be defined as the starting conditions from which forward numerical modelling can generate fracture stratigraphy. DEM can incorporate both stratigraphic and lateral heterogeneity, and enable mechanical and fracture stratigraphy to be characterised separately. Stratally bound stratified chert nodules below bedding surfaces generate closely spaced lateral heterogeneity in physical properties at stratigraphic mechanical interfaces. This generates extra complexity in natural fracture networks in addition to that caused by bed thickness and lithological physical properties. A series of representative geologically appropriate synthetic mechanical stratigraphic models were tested. Fracture networks generated in 15 DEM experiments designed to isolate and constrain the effects of nodular chert rhythmites on carbonate fracture stratigraphy are presented. The discrete element media used to model the elastic strengths of rocks contain 72,866 individual elements. Mechanical stratigraphies and the fracture networks generated are placed in a sequence stratigraphic framework. Nodular chert rhythmite successions are shown to be a distinct type of naturally fractured carbonate reservoir. Qualitative stratigraphic rules for predicting the distribution, lengths, spacing

  1. Quantitative geometric description of fracture systems in an andesite lava flow using terrestrial laser scanner data

    Science.gov (United States)

    Massiot, Cécile; Nicol, Andrew; Townend, John; McNamara, David D.; Garcia-Sellés, David; Conway, Chris E.; Archibald, Garth

    2017-07-01

    Permeability hosted in andesitic lava flows is dominantly controlled by fracture systems, with geometries that are often poorly constrained. This paper explores the fracture system geometry of an andesitic lava flow formed during its emplacement and cooling over gentle paleo-topography, on the active Ruapehu volcano, New Zealand. The fracture system comprises column-forming and platy fractures within the blocky interior of the lava flow, bounded by autobreccias partially observed at the base and top of the outcrop. We use a terrestrial laser scanner (TLS) dataset to extract column-forming fractures directly from the point-cloud shape over an outcrop area of ∼3090 m2. Fracture processing is validated using manual scanlines and high-resolution panoramic photographs. Column-forming fractures are either steeply or gently dipping with no preferred strike orientation. Geometric analysis of fractures derived from the TLS, in combination with virtual scanlines and trace maps, reveals that: (1) steeply dipping column-forming fracture lengths follow a scale-dependent exponential or log-normal distribution rather than a scale-independent power-law; (2) fracture intensities (combining density and size) vary throughout the blocky zone but have similar mean values up and along the lava flow; and (3) the areal fracture intensity is higher in the autobreccia than in the blocky zone. The inter-connected fracture network has a connected porosity of ∼0.5 % that promote fluid flow vertically and laterally within the blocky zone, and is partially connected to the autobreccias. Autobreccias may act either as lateral permeability connections or barriers in reservoirs, depending on burial and alteration history. A discrete fracture network model generated from these geometrical parameters yields a highly connected fracture network, consistent with outcrop observations.

  2. Identifying osteoporotic vertebral fracture

    OpenAIRE

    Griffith, James F.

    2015-01-01

    Osteoporosis per se is not a harmful disease. It is the sequela of osteoporosis and most particularly the occurrence of osteoporotic fracture that makes osteoporosis a serious medical condition. All of the preventative measures, investigations, treatment and research into osteoporosis have one primary goal and that is to prevent the occurrence of osteoporotic fracture. Vertebral fracture is by far and away the most prevalent osteoporotic fracture. The significance and diagnosis of vertebral f...

  3. Development of a fixation device for robot assisted fracture reduction of femoral shaft fractures: a biomechanical study.

    Science.gov (United States)

    Weber-Spickschen, T S; Oszwald, M; Westphal, R; Krettek, C; Wahl, F; Gosling, T

    2010-01-01

    Robot assisted fracture reduction of femoral shaft fractures provides precise alignment while reducing the amount of intraoperative imaging. The connection between the robot and the fracture fragment should allow conventional intramedullary nailing, be minimally invasive and provide interim fracture stability. In our study we tested three different reduction tools: a conventional External Fixator, a Reposition-Plate and a Three-Point-Device with two variations (a 40 degrees and a 90 degrees version). We measured relative movements between the tools and the bone fragments in all translation and rotation planes. The Three-Point-Device 90 degrees showed the smallest average relative displacement and was the only device able to withstand the maximum applied load of 70 Nm without failure of any bone fragment. The Three-Point-Device 90 degrees complies with all the stipulated requirements and is a suitable interface for robot assisted fracture reduction of femoral shaft fractures.

  4. Fracture prevention in men

    NARCIS (Netherlands)

    Geusens, PP; Sambrook, P.N.; Lems, W.F.

    2009-01-01

    The lifetime risk of experiencing a fracture in 50-year-old men is lower (20%) than the risk in women (50%). Consequently, much less research has been carried out on osteoporosis and fracture risk in men. Differences in the risk and incidence of fractures between men and women are related to differe

  5. Imaging of insufficiency fractures

    Energy Technology Data Exchange (ETDEWEB)

    Krestan, Christian [Department of Radiology, Medical University of Vienna, Vienna General Hospital, Waehringerstr. 18-20, 1090 Vienna (Austria)], E-mail: christian.krestan@meduniwien.ac.at; Hojreh, Azadeh [Department of Radiology, Medical University of Vienna, Vienna General Hospital, Waehringerstr. 18-20, 1090 Vienna (Austria)

    2009-09-15

    This review focuses on the occurrence, imaging and differential diagnosis of insufficiency fractures. Prevalence, the most common sites of insufficiency fractures and their clinical implications are discussed. Insufficiency fractures occur with normal stress exerted on weakened bone. Postmenopausal osteoporosis is the most common cause of insufficiency fractures. Other conditions which affect bone turnover include osteomalacia, hyperparathyroidism, chronic renal failure and high-dose glucocorticoid therapy. It is a challenge for the radiologist to detect and diagnose insufficiency fractures, and to differentiate them from other bone lesions. Radiographs are still the most widely used imaging method for identification of insufficiency fractures, but sensitivity is limited, depending on the location of the fractures. Magnetic resonance imaging (MRI) is a very sensitive tool to visualize bone marrow abnormalities associated with insufficiency fractures. Thin section, multi-detector computed tomography (MDCT) depicts subtle fracture lines allowing direct visualization of cortical and trabecular bone. Bone scintigraphy still plays a role in detecting fractures, with good sensitivity but limited specificity. The most important differential diagnosis is underlying malignant disease leading to pathologic fractures. Bone densitometry and clinical history may also be helpful in confirming the diagnosis of insufficiency fractures.

  6. Fracture development in shale and its relationship to gas accumulation

    Directory of Open Access Journals (Sweden)

    Wenlong Ding

    2012-01-01

    Full Text Available Shale with high quartz, feldspar and carbonate, will have low Poisson’s ratio, high Young’s modulus and high brittleness. As a result, the shale is conducive to produce natural and induced fractures under external forces. In general, there is a good correlation between fracture development in shale and the volume of brittle minerals present. Shale with high TOC or abnormally high pressure has well-developed fractures. Shale fracture development also shows a positive correlation with total gas accumulation and free gas volume, i.e., the better shale fractures are developed, the greater the gas accumulation and therefore the higher the gas production. Fractures provide migration conduits and accumulation spaces for natural gas and formation water, which are favorable for the volumetric increase of free natural gas. Wider fractures in shale result in gas loss. In North America, there is a high success ratio of shale gas exploration and high gas production from high-angle fracture zones in shale. Good natural gas shows or low yield producers in the Lower Paleozoic marine organic matter-rich rocks in the Sichuan Basin are closely related to the degree of fracture development in brittle shales.

  7. An analytical thermohydraulic model for discretely fractured geothermal reservoirs

    Science.gov (United States)

    Fox, Don B.; Koch, Donald L.; Tester, Jefferson W.

    2016-09-01

    In discretely fractured reservoirs such as those found in Enhanced/Engineered Geothermal Systems (EGS), knowledge of the fracture network is important in understanding the thermal hydraulics, i.e., how the fluid flows and the resulting temporal evolution of the subsurface temperature. The purpose of this study was to develop an analytical model of the fluid flow and heat transport in a discretely fractured network that can be used for a wide range of modeling applications and serve as an alternative analysis tool to more computationally intensive numerical codes. Given the connectivity and structure of a fracture network, the flow in the system was solved using a linear system of algebraic equations for the pressure at the nodes of the network. With the flow determined, the temperature in the fracture was solved by coupling convective heat transport in the fracture with one-dimensional heat conduction perpendicular to the fracture, employing the Green's function derived solution for a single discrete fracture. The predicted temperatures along the fracture surfaces from the analytical solution were compared to numerical simulations using the TOUGH2 reservoir code. Through two case studies, we showed the capabilities of the analytical model and explored the effect of uncertainty in the fracture apertures and network structure on thermal performance. While both sources of uncertainty independently produce large variations in production temperature, uncertainty in the network structure, whenever present, had a predominant influence on thermal performance.

  8. Effects of fracture contact areas on seismic attenuation due to wave-induced fluid flow

    Science.gov (United States)

    Germán Rubino, J.; Müller, Tobias M.; Milani, Marco; Holliger, Klaus

    2014-05-01

    Wave-induced fluid flow (WIFF) between fractures and the embedding matrix is considered to be a predominant seismic attenuation mechanism in fractured rocks. That is, due to the strong compressibility contrast between fractures and embedding matrix, seismic waves induce strong fluid pressure gradients, followed by local fluid flow between such regions, which in turn produces significant energy dissipation. Natural fractures can be conceptualized as two surfaces in partial contact, containing very soft and highly permeable material in the inner region. It is known that the characteristics of the fracture contact areas control the mechanical properties of the rock sample, since as the contact area increases, the fracture becomes stiffer. Correspondingly, the detailed characteristics of the contact area of fractures are expected to play a major role in WIFF-related attenuation. To study this topic, we consider a simple model consisting of a horizontal fracture located at the center of a porous rock sample and represented by a number of rectangular cracks of constant height separated by contact areas. The cracks are modelled as highly compliant, porous, and permeable heterogeneities, which are hydraulically connected to the background material. We include a number of rectangular regions of background material separating the cracks, which represent the presence of contact areas of the fracture. In order to estimate the WIFF effects, we apply numerical oscillatory relaxation tests based on the quasi-static poro-elastic equations. The equivalent undrained, complex plane-wave modulus, which allows to estimate seismic attenuation and velocity dispersion for the vertical direction of propagation, is expressed in terms of the imposed displacement and the resulting average vertical stress at the top boundary. In order to explore the effects of the presence of fracture contact areas on WIFF effects, we perform an exhaustive sensitivity analysis considering different

  9. Application of Discrete Fracture Modeling and Upscaling Techniques to Complex Fractured Reservoirs

    Science.gov (United States)

    Karimi-Fard, M.; Lapene, A.; Pauget, L.

    2012-12-01

    During the last decade, an important effort has been made to improve data acquisition (seismic and borehole imaging) and workflow for reservoir characterization which has greatly benefited the description of fractured reservoirs. However, the geological models resulting from the interpretations need to be validated or calibrated against dynamic data. Flow modeling in fractured reservoirs remains a challenge due to the difficulty of representing mass transfers at different heterogeneity scales. The majority of the existing approaches are based on dual continuum representation where the fracture network and the matrix are represented separately and their interactions are modeled using transfer functions. These models are usually based on idealized representation of the fracture distribution which makes the integration of real data difficult. In recent years, due to increases in computer power, discrete fracture modeling techniques (DFM) are becoming popular. In these techniques the fractures are represented explicitly allowing the direct use of data. In this work we consider the DFM technique developed by Karimi-Fard et al. [1] which is based on an unstructured finite-volume discretization. The mass flux between two adjacent control-volumes is evaluated using an optimized two-point flux approximation. The result of the discretization is a list of control-volumes with the associated pore-volumes and positions, and a list of connections with the associated transmissibilities. Fracture intersections are simplified using a connectivity transformation which contributes considerably to the efficiency of the methodology. In addition, the method is designed for general purpose simulators and any connectivity based simulator can be used for flow simulations. The DFM technique is either used standalone or as part of an upscaling technique. The upscaling techniques are required for large reservoirs where the explicit representation of all fractures and faults is not possible

  10. Proximal humerus fractures.

    Science.gov (United States)

    Price, Matthew C; Horn, Pamela L; Latshaw, James C

    2013-01-01

    Proximal humerus fractures are among the most common fractures associated with osteoporosis. With an aging population, incidence of these fractures will only increase. The proximal humerus not only forms the lateral portion of the shoulder articulation but also has significant associations with musculoskeletal and neurovascular structures. As a result, fractures of the proximal humerus can significantly impact not only the function of the shoulder joint, but the health and function of the entire upper extremity as well. Understanding of these fractures, the management options, and associated nursing care, can help reduce morbidity rate and improve functional outcomes.

  11. Stress fractures in runners.

    Science.gov (United States)

    McCormick, Frank; Nwachukwu, Benedict U; Provencher, Matthew T

    2012-04-01

    Stress fractures are a relatively common entity in athletes, in particular, runners. Physicians and health care providers should maintain a high index of suspicion for stress fractures in runners presenting with insidious onset of focal bone tenderness associated with recent changes in training intensity or regimen. It is particularly important to recognize “high-risk” fractures, as these are associated with an increased risk of complication. A patient with confirmed radiographic evidence of a high-risk stress fracture should be evaluated by an orthopedic surgeon. Runners may benefit from orthotics, cushioned sneakers, interval training, and vitamin/calcium supplementation as a means of stress fracture prevention.

  12. Role of MRI in hip fractures, including stress fractures, occult fractures, avulsion fractures

    Energy Technology Data Exchange (ETDEWEB)

    Nachtrab, O. [Department of Radiology, The Robert Jones and Agnes Hunt Orthopaedic Hospital, Gobowen, Oswestry Shropshire SY10 7AG (United Kingdom); Cassar-Pullicino, V.N., E-mail: Victor.Pullicino@rjah.nhs.uk [Department of Radiology, The Robert Jones and Agnes Hunt Orthopaedic Hospital, Gobowen, Oswestry Shropshire SY10 7AG (United Kingdom); Lalam, R.; Tins, B.; Tyrrell, P.N.M.; Singh, J. [Department of Radiology, The Robert Jones and Agnes Hunt Orthopaedic Hospital, Gobowen, Oswestry Shropshire SY10 7AG (United Kingdom)

    2012-12-15

    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.

  13. Fractures in multiple sclerosis

    DEFF Research Database (Denmark)

    Stenager, E; Jensen, K

    1991-01-01

    In a cross-sectional study of 299 MS patients 22 have had fractures and of these 17 after onset of MS. The fractures most frequently involved the femoral neck and trochanter (41%). Three patients had had more than one fracture. Only 1 patient had osteoporosis. The percentage of fractures increased...... with increasing age and disease duration. Among 34 deceased MS patients 4 had had fractures. These findings are discussed in relation to physical and cognitive impairment in MS. A case-control study is recommended....

  14. Nature Watch

    Science.gov (United States)

    Sterling, Donna R.

    2010-01-01

    Children are naturally curious about the world in which they live. To focus this sense of wonder, have your students investigate their local habitat as it changes over the year. This multiseason study will build connections and add relevance to the habitats that children learn about. This series of activities for grades 4-6 explores the changing…

  15. Measurement and analysis of fractures in vertical, slant, and horizontal core, with examples from the Mesaverde formation

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, J.C. (Sandia National Labs., Albuquerque, NM (United States)); Hill, R.E. (CER Corp., Las Vegas, NV (United States))

    1991-01-01

    Optimum analysis of natural fracture characteristics and distributions in reservoirs requires conscientious supervision of coring operations, on-site core processing, careful layout and marketing of the core, and detailed measurement of fracture characteristics. Natural fractures provide information on the in situ permeability system, and coring-induced fractures provide data on the in situ stresses. Fracture data derived from vertical core should include fracture height, type and location of fracture terminations with respect to lithologic heterogeneity, fracture planatary and roughness, and distribution with depth. Fractures in core from either a vertical or a deviated well will yield information on dip, dip azimuth, strike, mineralization, and the orientation of fractures relative to the in situ stresses. Only measurements of fractures in core from a deviated/horizontal well will provide estimates of fracture spacing and porosity. These data can be graphed and cross-plotted to yield semi-quantitative fracture characteristics for reservoir models. Data on the orientations of fractures relative to each other in unoriented core can be nearly as useful as the absolute orientations of fractures. A deviated pilot hole is recommended for fracture assessment prior to a drilling horizontal production well because it significantly enhances the chances of fracture intersection, and therefore of fracture characterization. 35 refs., 20 figs., 2 tabs.

  16. Naturally fractured tight gas reservoirs detection optimization

    Energy Technology Data Exchange (ETDEWEB)

    Hoekstra, P. [Coleman Research Corp., Orlando, FL (United States)

    1995-04-01

    This contract is a joint project between METC and Louisiana Land and Exploration, planned to extend for 3 years. Substantial help and key information has been provided at the field by the owner/operator. All their well logs, cores, production data, geologic data, and geophysical data are available for study in this project. Their commitment in this technology development is demonstrated by their proposed contribution in the form of cost sharing: (1) obtaining the P-Wave (compressional wave) 3-D survey, (2) furnishing a borehole in which to acquire the 9-C vertical seismic profile (VSP), and (3) drilling and completing a test well for verification of the seismic anomaly. Also of significance is the direct involvement and participation of their professional staff. This staff has been responsible for generating and maintaining the database at the field and will form part of the team which evaluates the seismic data`s findings.

  17. The Fractured Nature of British Politics

    CERN Document Server

    Molinero, Carlos; Smith, Duncan; Batty, Michael

    2015-01-01

    The outcome of the British General Election to be held in just over one week's time is widely regarded as the most difficult in living memory to predict. Current polls suggest that the two main parties are neck and neck but that there will be a landslide to the Scottish Nationalist Party with that party taking most of the constituencies in Scotland. The Liberal Democrats are forecast to loose more than half their seats and the fringe parties of whom the UK Independence Party is the biggest are simply unknown quantities. Much of this volatility relates to long-standing and deeply rooted cultural and nationalist attitudes that relate to geographical fault lines that have been present for 500 years or more but occasionally reveal themselves, at times like this. In this paper our purpose is to raise the notion that these fault lines are critical to thinking about regionalism, nationalism and the hierarchy of cities in Great Britain (excluding Northern Ireland). We use a percolation method (Arcaute et al. 2015) to...

  18. Hydraulic fracture model comparison study: Complete results

    Energy Technology Data Exchange (ETDEWEB)

    Warpinski, N.R. [Sandia National Labs., Albuquerque, NM (United States); Abou-Sayed, I.S. [Mobil Exploration and Production Services (United States); Moschovidis, Z. [Amoco Production Co. (US); Parker, C. [CONOCO (US)

    1993-02-01

    Large quantities of natural gas exist in low permeability reservoirs throughout the US. Characteristics of these reservoirs, however, make production difficult and often economic and stimulation is required. Because of the diversity of application, hydraulic fracture design models must be able to account for widely varying rock properties, reservoir properties, in situ stresses, fracturing fluids, and proppant loads. As a result, fracture simulation has emerged as a highly complex endeavor that must be able to describe many different physical processes. The objective of this study was to develop a comparative study of hydraulic-fracture simulators in order to provide stimulation engineers with the necessary information to make rational decisions on the type of models most suited for their needs. This report compares the fracture modeling results of twelve different simulators, some of them run in different modes for eight separate design cases. Comparisons of length, width, height, net pressure, maximum width at the wellbore, average width at the wellbore, and average width in the fracture have been made, both for the final geometry and as a function of time. For the models in this study, differences in fracture length, height and width are often greater than a factor of two. In addition, several comparisons of the same model with different options show a large variability in model output depending upon the options chosen. Two comparisons were made of the same model run by different companies; in both cases the agreement was good. 41 refs., 54 figs., 83 tabs.

  19. [Fractures of carpal bones].

    Science.gov (United States)

    Lögters, T; Windolf, J

    2016-10-01

    Fractures of the carpal bones are uncommon. On standard radiographs fractures are often not recognized and a computed tomography (CT) scan is the diagnostic method of choice. The aim of treatment is to restore pain-free and full functioning of the hand. A distinction is made between stable and unstable carpal fractures. Stable non-displaced fractures can be treated conservatively. Unstable and displaced fractures have an increased risk of arthritis and non-union and should be stabilized by screws or k‑wires. If treated adequately, fractures of the carpal bones have a good prognosis. Unstable and dislocated fractures have an increased risk for non-union. The subsequent development of carpal collapse with arthrosis is a severe consequence of non-union, which has a heterogeneous prognosis.

  20. Orbital fractures: a review

    Directory of Open Access Journals (Sweden)

    Jeffrey M Joseph

    2011-01-01

    Full Text Available Jeffrey M Joseph, Ioannis P GlavasDivision of Ophthalmic Plastic and Reconstructive Surgery, Department of Ophthalmology, School of Medicine, New York University, New York, NY, USA; Manhattan Eye, Ear, and Throat Hospital, New York, NY, USAAbstract: This review of orbital fractures has three goals: 1 to understand the clinically relevant orbital anatomy with regard to periorbital trauma and orbital fractures, 2 to explain how to assess and examine a patient after periorbital trauma, and 3 to understand the medical and surgical management of orbital fractures. The article aims to summarize the evaluation and management of commonly encountered orbital fractures from the ophthalmologic perspective and to provide an overview for all practicing ophthalmologists and ophthalmologists in training.Keywords: orbit, trauma, fracture, orbital floor, medial wall, zygomatic, zygomatic complex, zmc fracture, zygomaticomaxillary complex fractures 

  1. Oblique Axis Body Fracture

    DEFF Research Database (Denmark)

    Takai, Hirokazu; Konstantinidis, Lukas; Schmal, Hagen

    2016-01-01

    Purpose. Anderson type III odontoid fractures have traditionally been considered stable and treated conservatively. However, unstable cases with unfavorable results following conservative treatment have been reported. Methods. We present the cases of two patients who sustained minimally displaced...... Anderson type III fractures with a characteristic fracture pattern that we refer to as "oblique type axis body fracture." Results. The female patients aged 90 and 72 years, respectively, were both diagnosed with minimally displaced Anderson type III fractures. Both fractures had a characteristic "oblique...... type" fracture pattern. The first patient was treated conservatively with cervical spine immobilization in a semirigid collar. However, gross displacement was noted at the 6-week follow-up visit. The second patient was therefore treated operatively by C1-C3/4 posterior fusion and the course...

  2. Constraints on 3D fault and fracture distribution in layered volcanic- volcaniclastic sequences from terrestrial LIDAR datasets: Faroe Islands

    Science.gov (United States)

    Raithatha, Bansri; McCaffrey, Kenneth; Walker, Richard; Brown, Richard; Pickering, Giles

    2013-04-01

    the upper lava unit and therefore fracture concentration is higher, while in the lower lava unit, the fault zone is narrower and thus fracture concentration is also low. Both field observations and the DFN model indicate that the faults and fractures are steeper in the basalts, and shallower in the volcaniclastic sequences, giving a 'stepped' geometry. To assess the nature of sub-seismic fracturing, fracture attributes (connectivity, spacing, length, and orientation) within the model were analysed quantitatively. Continuing work will integrate the detailed field analysis fully, including 1D and 2D fracture transects, structural logging and mapping as well as microstructural characterisation from collected field samples, to understand the complex nature of fracture networks in inter-layered basalt-volcaniclastic sequences. Fracture attributes, such as the shape, length, aspect ratio, curvature and aperture, will be quantified to provide key parameters for fluid flow simulation. Once these attributes have been assessed, experimental data (porosity and permeability) will be incorporated into the DFN model to constrain the fluid flow potential within these inter-layered volcanic sequences.

  3. Geomechanical paleostress inversion using fracture data

    Science.gov (United States)

    Maerten, Laurent; Maerten, Frantz; Lejri, Mostfa; Gillespie, Paul

    2016-08-01

    We describe a fast geomechanically-based paleostress inversion technique that uses observed fracture data to constrain stress through multiple simulations. The method assumes that the local stress field around individual fractures is heterogeneous and derives the far field tectonic stress, that we also call the far field boundary conditions. We show how such far field tectonic stress can be recovered through a mechanical stress inversion technique using local observations of natural fractures (i.e. mechanical type, orientation and location). We test the paleostress inversion against outcrop analogues of fractured carbonates from both Nash Point, U.K., where there are well exposed faults and joints and the Matelles, France, where there are well exposed faults, veins and stylolites. We demonstrate through these case studies how the method can be efficiently applied to natural examples and we highlight its advantages and limitations. We discuss how such method could be applied to subsurface problems and how it can provide complementary constraints to drive discrete fracture models for better fractured reservoir characterization and modelling.

  4. The hydraulic fracturing of geothermal formations

    Energy Technology Data Exchange (ETDEWEB)

    Naceur, K. Ben; Economides, M.J.; Schlumberger, Dowell

    1988-01-01

    Hydraulic fracturing has been attempted in geothermal formations as a means to stimulate both production and injection wells. Since most geothermal formations contain fissures and on occasion massive natural fissures, the production behavior of the man-made fractures results in certain characteristic trends. A model is offered that allows the presence of a finite or infinite conductivity fracture intercepting a fissured medium. The method is based on a numerical discretization of the formation allowing transient interporosity flow. Type curves for pressure drawdown and cumulative production are given for infinite acting and closed reservoirs. Since most of the fissured formations exhibit a degree of anisotropy, the effects of the orientation of the hydraulic fracture with respect to the fissure planes, and of the ratio between the directional permeabilities are then discussed. Guidelines are offered as to the size of appropriate stimulation treatments based on the observed fissured behavior of the reservoir.

  5. [Fracture endoprosthesis of distal humerus fractures].

    Science.gov (United States)

    Müller, L P; Wegmann, K; Burkhart, K J

    2013-08-01

    The treatment of choice for fractures of the distal humerus is double plate osteosynthesis. Due to anatomical preshaped angle stable plates the primary stability and management of soft tissues has been improved. However, osteoporotic comminuted fractures in the elderly are often not amenable to stable osteosynthesis and total elbow arthroplasty has been established as an alternative therapy. Although complication rates have been reduced, complications of total elbow arthroplasty are still much more frequent than in total hip replacement. Furthermore, patients are advised not to exceed a weight bearing of 5 kg. Therefore, the indications for elbow arthroplasty must be evaluated very strictly and should be reserved for comminuted distal humeral fractures in the elderly with poor bone quality that are not amenable to stable osteosynthesis or for simple fractures in cases of preexisting symptomatic osteoarthritis. This article introduces and discusses modern concepts of elbow arthroplasty, such as modular convertible prosthesis systems, hemiarthroplasty and radial head replacement in total elbow arthroplasty.

  6. Permeability Enhancement in Enhanced Geothermal System as a result of Hydraulic Fracturing and Jacking

    Science.gov (United States)

    Jalali, Mohammadreza; Klepikova, Maria; Fisch, Hansruedi; Amann, Florian; Loew, Simon

    2016-04-01

    A decameter-scale in-situ hydraulic stimulation and circulation (ISC) experiment has been initiated by the newly-founded Swiss Competence Centre for Energy Research - Supply of Electricity (SCCER-SoE) at Nagra's Grimsel Test Site (GTS) as a part of the work-package WP1 of the Deep Underground Laboratory (DUG-Lab) initiative. The experiment area is situated in the southern part of the GTS in a low fracture density volume of the Grimsel granodiorite. The hydraulic properties of the granitic rock mass are supposed to be similar to those expected in the crystalline basement of the alpine foreland where deep enhanced geothermal systems might be developed in future. The main objectives of the multi-disciplinary experiment are to provide a high resolution pre- and post-stimulation characterization of fracture permeability and connectivity, to investigate patterns of preferential flow paths, to describe the pressure propagation during the stimulation phases and to evaluate the efficiency of the fracture-matrix heat exchanger. A comprehensive test & monitoring layout including a fair number of boreholes instrumented with a variety of sensors (e.g. pressure, strain, displacement, temperature, and seismic sensors) is designed to collect detailed data during multiple hydraulic stimulation runs. The diffusion of fluid pressure is expected to be governed mainly by the properties and geometry of the existent fracture network. The hydraulic transmissivity of fractures are in the range of 10-7 to 10-9 m2/s whereas the matrix rock has a very low hydraulic conductivity (K ˜ 10-12 m/s). As part of the stress measurement campaign during the pre-stimulation phase of the ISC experiment, a series of hydraulic fracturing (HF) and hydraulic tests in pre-existing fractures (HTPF) were conducted. The tests were accompanied by micro-seismic monitoring within several observation boreholes to investigate the initiation and propagation of the induced fractures. Together with results from over

  7. 新场气田须二气藏天然裂缝有效性定量表征方法及应用%Quantification characterization of the valid natural fractures in the 2nd Xu Member, Xinchang gas field

    Institute of Scientific and Technical Information of China (English)

    邓虎成; 周文; 周秋媚; 陈文玲; 张昊天

    2013-01-01

    天然裂缝是地层中广泛分布的一种地质构造现象,当其在油气开发过程中保持一定有效性时具有重要作用,其有效程度高低是裂缝性油气藏高产富集的关键.本次研究以川西新场气田须二气藏裂缝特征及成因认识为基础,利用气藏各类动静态资料对裂缝张开度、裂缝渗透率、裂缝孔隙度等参数进行解释和评价,明确了不同资料计算获取裂缝参数的物理含义及相互之间的关系,为裂缝有效性评价奠定了基础.文中以井筒附近、地质模型网格单元体内裂缝网络系统作为裂缝有效性定量表征对象,通过裂缝网络系统裂缝参数的分布特征,选取并组合了参数分布的特征变量从而建立了裂缝有效性定量表征指标;基于裂缝有效性定量表征方法和建立的定量表征指标对新场气田须二气藏单井产层段裂缝的有效性及气藏裂缝有效性的纵横变化规律进行了研究和评价,其评价结果与区域构造、应力场分布、井下监测、生产动态具有很好的一致性.本文对油气藏中天然裂缝有效性的认识和定量表征方法为裂缝性油气藏地质建模中裂缝有效参数场的建立和数值模拟工作奠定了基础,为裂缝性油气藏的描述和生产动态研究提供了方向和思路.%The natural fracture is a geological phenomenon which is widely distributed in the strata, and plays an important role in the oil & gas development. The fractures effectiveness level is the key to get high oil & gas yielding and enrichment in fractured oil & gas reservoirs. Based on the characteristics and igneous cognition of fractures and all kinds of static and dynamic data in the 2nd Xu Member gas reservoirs in Xinchang gas field in western Sichuan, the parameters such as aperture, permeability and porosity of fractures are interpreted and evaluated. The physical meanings of fracture parameters obtained from different data are clear that laid the

  8. Hydraulic Fracturing, Wastewater Injection and Unintended Earthquakes (Invited)

    Science.gov (United States)

    Ellsworth, W. L.

    2013-12-01

    It has long been known that increasing the pore pressure within a pre-stressed fault can induce an earthquake by reducing the effective normal stress and thereby the frictional strength of the fault. Underground fluid pressures are routinely modified by a wide range of industrial activities including impoundment of reservoirs, mining, and petroleum production, all of which are known to have potential for inducing earthquakes. Recently, attention has been drawn to the earthquake hazard associated with the production of oil and gas from previously unproductive formations. Earthquakes can be induced as part of the process to stimulate the production from tight shale formations, or by disposal of wastewater associated with stimulation and production. In this talk, I review recent investigations of both activities with a focus on the emerging understanding of the development of predictive models for both seismicity and risk. By design, hydraulic fracturing induces numerous high-frequency microseismic events as part of the process of creating a connected fracture network to enhance formation permeability. During the brief time (hours) that high fluid pressure is applied to the well bore, seismic events occur as a combination tensile (hydrofracture) and shear (hydroshear) failures. The fluid volume injected in a single hydrofrac stage is commonly of the order of several thousand cubic meters. Growth of the fracture network typically follows square-root scaling with time, suggesting a diffusive growth mechanism. Magnitudes are normally below zero for events in the target formation. Larger, unintended events sometimes occur and available evidence points to shear failure of pre-existing faults as their source. Earthquakes with magnitudes as large as Mw 3.6 occurred during hydraulic fracturing operations in the Horn River Basin, B. C., Canada. Some of these occurred before the diffusive pressure front would have reached the hypocenter, suggesting rapid transmission of pore

  9. An upscaling procedure for fractured reservoirs with embedded grids

    Science.gov (United States)

    Fumagalli, Alessio; Pasquale, Luca; Zonca, Stefano; Micheletti, Stefano

    2016-08-01

    Upscaling of geological models for reservoir simulation is an active and important area of research. In particular, we are interested in reservoirs where the rock matrix exhibits an intricate network of fractures, which usually acts as a preferential path to the flow. Accounting for fractures' contribution in the simulation of a reservoir is of paramount importance. Here we have focused on obtaining effective parameters (e.g., transmissibility) on a 3-D computational grid on the reservoir scale, which account for the presence, at a finer spatial scale, of fractures and a network of fractures. We have essentially followed the idea illustrated in Karimi-Fard et al. (2006), yet this work has some notable aspects of innovation in the way the procedure has been implemented, and in its capability to consider rather general corner-point grids, like the ones normally used in reservoir simulations in the industry, and complex and realistic fracture networks, possibly not fully connected inside the coarse cells. In particular, novel contribution is the employment of an Embedded Discrete Fracture Model (EDFM) for computing fracture-fracture and matrix-fracture transmissibilities, with a remarkable gain in speedup. The output is in the form of transmissibility that, although obtained by considering single-phase flow, can be used for coarse-scale multiphase reservoir simulations, also via industrial software, such as Eclipse, Intersect, or GPRS. The results demonstrate the effectiveness and computational efficiency of the numerical procedure which is now ready for further testing and industrialization.

  10. Preferential flow characterization in fractured aquifer by injecting dissolved oxygen in boreholes

    Science.gov (United States)

    Vurro, Michele; Donnaloia, Mietta; Masciopinto, Costantino; Pennetta, Luigi; Robbins, Gary; Vitale, Sarah

    2016-04-01

    A new approach to identify contributing fractures and wellbore flow in fractured and karst aquifers is presented. It is time efficient, low cost and based on a benign tracer: the dissolved oxygen (DO). The method was already applied by other scientists to test fractured crystalline rock wells. The DO method consists in elevating water DO concentration in a borehole by bubbling air at assigned water depths using a porous polypropylene tube (bubbler) connected to a compressed air tank with tubing. After the aeration, the resulting profile should be a linear increase in DO with depth due to the effects of water pressure on oxygen solubility. Any changes in the DO profile will be then observed when water flows into and through the well. DO dilution can be used to locate inflowing fractures and to define active flow zones in wells. If there is no change in the DO profile, a "dead zones" in the well is present, that is to say no flow is taking place or can be identified. The DO tests in this work have been carried out in the industrial area of Bari, at the experimental station, constituted by five wells drilled at the CNR-IRSA. The wells penetrate karstic limestone. Results show enhanced flow through at depths between 32 and 37 meters below the water level: DO concentrations decrease until they reach values close to 0 mg/l. DO curves show also the presence of inflowing fractures, as testified by the decrease in the DO concentrations due to the effects of water dilution, at depths of 4 and 9 meters (below the water table) in the north well, at 4 and 10 meters in the central well, and at 30 meters in the south well. The benefits of utilizing DO as a tracer include ease of accessibility, low cost and time-efficiency as well as non-toxic nature of the tracer and no impact on flow conditions.

  11. Jaw fractures in children.

    Science.gov (United States)

    Kotilainen, R; Kärjä, J; Kullaa-Mikkonen, A

    1990-03-01

    From a total of 350 jaw fractures treated in 1980-1984 at Kuopio University Central Hospital, 20% were in children. These injuries were evaluated retrospectively regarding age, sex, incidence and etiology. Forty-five of the patients were boys and 25 girls. The frequency of maxillary and mandibular fractures in 70 young patients was 28.6%. The most common type of bone fractures was fracture of the alveolar process, which was prevalent in persons with mixed dentition. Before the age of 7 years, falls from height were the common causes of jaw fractures. The major cause of the jaw fractures in children from 7 to 15 years old was road accidents (47.1%), especially in boys. Most of these were cycling accidents, only a few patients were victims of automobile accidents. In addition, about one third (25.7%) of the patients were treated in the hospital because of multiple injuries to other organs.

  12. Growing skull fracture

    Directory of Open Access Journals (Sweden)

    Mihajlović Miljan H.

    2006-01-01

    Full Text Available Background. Growing skull fracture or craniocerebral erosion is a rare complication of linear skull fracture in childhood. It is characterized by progressive diastatic enlargement of the fracture line, which leads to a cranial defect, dural cleft, and cerebral herniation. It is presented as a soft pulsabile scalp swelling above the fracture, with a clear cranial defect. Case report. In this paper we presented a patient, an 8-month-old boy with the growing skull fracture revealed four weeks after the injury. After the surgical treatment, the boy was in a good general condition without the presence of neurologic impairment. Conclusion. Early recognition of craniocerebral erosion is very important. Timely detection prevents further progression of the disease and the evolution of neurological impairment. Surgery is the method of choice for treating a growing skull fracture .

  13. Pelvic fractures and mortality.

    OpenAIRE

    K.H. Chong; DeCoster, T.; Osler, T.; Robinson, B.

    1997-01-01

    A retrospective study of all patients (N = 343) with pelvic fractures admitted to our trauma service was conducted to evaluate the impact of pelvic fractures on mortality. All patients sustained additional injuries with an average Injury Severity Score (ISS) of twenty. Thirty-six patients died. This group had more severe pelvic fractures as graded by the Tile classification as well as a greater number and severity of associated injuries. Six patients died as a direct result of pelvic hemorrha...

  14. Oblique Axis Body Fracture

    DEFF Research Database (Denmark)

    Takai, Hirokazu; Konstantinidis, Lukas; Schmal, Hagen;

    2016-01-01

    was uneventful. Conclusions. Oblique type axis body fractures resemble a highly unstable subtype of Anderson type III fractures with the potential of severe secondary deformity following conservative treatment, irrespective of initial grade of displacement. The authors therefore warrant a high index of suspicion......Purpose. Anderson type III odontoid fractures have traditionally been considered stable and treated conservatively. However, unstable cases with unfavorable results following conservative treatment have been reported. Methods. We present the cases of two patients who sustained minimally displaced...

  15. A REVISED SOLUTION OF EQUIVALENT PERMEABILITY TENSOR FOR DISCONTINUOUS FRACTURES

    Institute of Scientific and Technical Information of China (English)

    HE Ji; CHEN Sheng-hong; SHAHROUR Isam

    2012-01-01

    The equivalent permeability tensor is essential to the application of the equivalent porous media model in the numerical seepage simulation for fractured rock masses.In this paper,a revised solution of the equivalent permeability tensor is proposed to represent the influence of the fracture connectivity in discontinuous fractures.A correction coefficient is involved to reflect the complex seepage flow type through the rock bridge.This correction coefficient is back analyzed from single-hole packer tests,based on the Artificial Neural Network (ANN) back analysis and the Finite Element Method (FEM) seepage simulation.The limitation of this back analysis algorithm is that the number of single-hole packer tests should be equal or greater than the number of fracture sets,and three is the maximum number of the fracture sets.The proposed solution and the back analysis algorithm are applied in the permeability measurement and the seepage simulation for the Xiaowan arch dam foundation.

  16. [(Impending) pathological fracture].

    Science.gov (United States)

    Sutter, P M; Regazzoni, P

    2002-01-01

    Pathological fractures will be encountered in increasing frequency due to more patients with cancer, surviving a longer period. The skeleton is the third most frequent localization for metastases. Breast cancer is still the most common primary tumor, but bone metastases from lung cancer seem to be diagnosed more and more. Despite of finding metastases most often in the spinal column, fractures are seen mostly at the femoral site. A pathological fracture and, in almost all cases, an impending fracture are absolute indication for operation. An exact definition of an "impending fracture" is still lacking; it is widely accepted, that 50 per cent of bone mass must be destroyed before visualization in X-ray is possible, thus defining an impending fracture. The score system by Mirels estimates the fracture risk by means of four parameters (localization, per cent of destructed bone mass, type of metastasis, pain). Improving quality of life, relieving pain, preferably with a single operation and a short length of stay are the goals of (operative) treatment. For fractures of the proximal femur, prosthetic replacement, for fractures of the subtrochanteric region or the shaft, intramedullary nails are recommended. Postoperative radiation therapy possibly avoids tumor progression. In patient with a good long term prognosis, tumor should be removed locally aggressive.

  17. Fracture mechanics safety approaches

    Energy Technology Data Exchange (ETDEWEB)

    Roos, E.; Schuler, X.; Eisele, U. [Materials Testing Inst. (MPA), Univ. of Stuttgart (Germany)

    2004-07-01

    Component integrity assessments require the knowledge of reliable fracture toughness parameters characterising the initiation of the failure process in the whole relevant temperature range. From a large number of fracture mechanics tests a statistically based procedure was derived allowing to quantify the initiation of fracture toughness as a function of temperature as a closed function as well as the temperature dependence of the cleavage instability parameters. Alternatively to the direct experimental determination one also can use a correlation between fracture toughness and notch impact energy. (orig.)

  18. Scaphoid fractures in children

    Directory of Open Access Journals (Sweden)

    Gajdobranski Đorđe

    2014-01-01

    Full Text Available Introduction. Scaphoid fractures are rare in childhood. Diagnosis is very difficult to establish because carpal bones are not fully ossified. In suspected cases comparative or delayed radiography is used, as well as computerized tomography, magnetic resonance imaging, ultrasound and bone scintigraphy. Majority of scaphoid fractures are treated conservatively with good results. In case of delayed fracture healing various types of treatment are available. Objective. To determine the mechanism of injury, clinical healing process, types and outcome of treatment of scaphoid fractures in children. Methods. We retrospectively analyzed patients with traumatic closed fracture of the scaphoid bone over a ten-year period (2002-2011. The outcome of the treatment of “acute” scaphoid fracture was evaluated using the Mayo Wrist Score. Results. There were in total 34 patients, of mean age 13.8 years, with traumatic closed fracture of the scaphoid bone, whose bone growth was not finished yet. Most common injury mechanism was fall on outstretched arm - 76% of patients. During the examined period 31 children with “acute” fracture underwent conservative treatment, with average immobilization period of 51 days. Six patients were lost to follow-up. In the remaining 25 patients, after completed rehabilitation, functional results determined by the Mayo Wrist Score were excellent. Conclusion. Conservative therapy of “acute” scaphoid fractures is an acceptable treatment option for pediatric patients with excellent functional results.

  19. Atraumatic First Rib Fracture

    Directory of Open Access Journals (Sweden)

    Koray Aydogdu

    2014-12-01

    Full Text Available Rib fractures are usually seen after a trauma, while atraumatic spontaneous rib fractures are quite rare. A first rib fracture identified in our 17 years old female patient who had not a history of trauma except lifting a heavy weight was examined in details in terms of the potential complications and followed-up for a long time. We presented our experience on this case with atraumatic first rib fracture that has different views for the etiology in light of the literature.

  20. Reassessment of the Bahamas Fracture Zone

    Energy Technology Data Exchange (ETDEWEB)

    Ball, M.M. (Geological Survey, Evergreen, CO (United States))

    1991-03-01

    The Bahamas Fracture Zone trends northwestward across south Florida and the Western Florida shelf, and it appears to connect with the Gilbertown-Pickens-Pollard portion of the circum-Gulf of Mexico fault system. Along the fracture zone's trend, seismic reflection data reveal normal displacement in the Late Jurassic section of a kilometer, on a down-to-the-west fault, 9 km east of the east end of Destin dome in the Apalachicola basin. This fault was active in Late Jurassic and Early Cretaceous time during the gulf spreading event. The Middle Jurassic Louann Salt thins abruptly to the east across this fault. Toward the southeast, where the fracture zone crosses the Florida peninsula, gravity data have previously been interpreted to indicate coincidence of the Bahamas Fracture Zone with a hinge zone attended by relief on the Mohorovicic discontinuity. This interpretation is an artifact resulting from the use of erroneously low densities for the sedimentary fill of the South Florida basin. The inclusion of a nonexistent negative component for the basin's sedimentary fill necessitated the inclusion of an equally nonexistent positive contribution from relief on the Moho in order to match the observed anomaly. Although northwestward-trending faults do cross south Florida and the Western Florida shelf, the role of the Bahamas Fracture Zone as a boundary between continental and transitional or oceanic crust is insupportable.

  1. Mass transport in fracture media: impact of the random function model assumed for fractures conductivity; Transporte de masa en medio fracturado: impacto del modelo estocastico de conductividad en las fracturas

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-07-01

    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.

  2. Connectivity of communication networks

    CERN Document Server

    Mao, Guoqiang

    2017-01-01

    This book introduces a number of recent developments on connectivity of communication networks, ranging from connectivity of large static networks and connectivity of highly dynamic networks to connectivity of small to medium sized networks. This book also introduces some applications of connectivity studies in network optimization, in network localization, and in estimating distances between nodes. The book starts with an overview of the fundamental concepts, models, tools, and methodologies used for connectivity studies. The rest of the chapters are divided into four parts: connectivity of large static networks, connectivity of highly dynamic networks, connectivity of small to medium sized networks, and applications of connectivity studies.

  3. 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.

  4. Granite microcracks: Structure and connectivity at different depths

    Science.gov (United States)

    Song, Fan; Dong, Yan-Hui; Xu, Zhi-Fang; Zhou, Peng-Peng; Wang, Li-Heng; Tong, Shao-Qing; Duan, Rui-Qi

    2016-07-01

    Granite is one rock type used to host high-level radioactive waste repositories, and the structure of microcracks in the rock can influence its hydraulic characteristics. Thus, a quantitative analysis of granite microcracks is relevant for understanding the hydrogeological characteristics of the rocks surrounding geological repositories. The analysis can also contribute scientific data to a seepage model for low permeability rocks and materials with microscopic pores. In this study, seven granite core samples were drilled from different depths up to 600 m in Alxa, Inner Mongolia, China. Using a grid survey method and image processing technology, micrographs were converted into binary images of microcracks. The geometric parameters of the microcracks, including their quantity, width, cranny ratio, crack intersections and dimensional parameters of the fracture network, were analyzed in order to fully describe their spatial distribution. In addition, the morphological characteristics and elemental compositions of the microcracks were analyzed by scanning electron microscopy energy dispersive X-ray analysis (SEM-EDS), and the natural moisture content was also determined through heated. Finally, two-dimensional microcrack network seepage models of the granite samples were simulated using the Lattice Boltzmann method (LBM), which revealed the influence of the microcrack structure on their connectivity. The results show that the growth and development of microcracks in the granite samples generally decreases as sampling depth increases in this study area. Connectivity is positively correlated with a number of the geometric parameters: the quantity of microcracks, the cranny ratio, the number of crack intersections and dimensional parameters of the fracture network, which is revealed in the two-dimensional microcrack network seepage models for these granite samples.

  5. Disclosure of hydraulic fracturing fluid chemical additives: analysis of regulations.

    Science.gov (United States)

    Maule, Alexis L; Makey, Colleen M; Benson, Eugene B; Burrows, Isaac J; Scammell, Madeleine K

    2013-01-01

    Hydraulic fracturing is used to extract natural gas from shale formations. The process involves injecting into the ground fracturing fluids that contain thousands of gallons of chemical additives. Companies are not mandated by federal regulations to disclose the identities or quantities of chemicals used during hydraulic fracturing operations on private or public lands. States have begun to regulate hydraulic fracturing fluids by mandating chemical disclosure. These laws have shortcomings including nondisclosure of proprietary or "trade secret" mixtures, insufficient penalties for reporting inaccurate or incomplete information, and timelines that allow for after-the-fact reporting. These limitations leave lawmakers, regulators, public safety officers, and the public uninformed and ill-prepared to anticipate and respond to possible environmental and human health hazards associated with hydraulic fracturing fluids. We explore hydraulic fracturing exemptions from federal regulations, as well as current and future efforts to mandate chemical disclosure at the federal and state level.

  6. Open tibial shaft fractures: II. Definitive management and limb salvage.

    Science.gov (United States)

    Melvin, J Stuart; Dombroski, Derek G; Torbert, Jesse T; Kovach, Stephen J; Esterhai, John L; Mehta, Samir

    2010-02-01

    Definitive treatment of open fractures of the tibial diaphysis is challenging. The high-energy nature of these fractures, as well as the contamination of the fracture site and devitalization of the soft-tissue envelope, greatly increases the risk of infection, nonunion, and wound complications. The goals of definitive treatment include wound coverage or closure; prevention of infection; restoration of length, alignment, rotation, and stability; fracture healing; and return of function. Advances in orthobiologics, modern plastic surgical techniques, and fracture stabilization methods, most notably locked intramedullary nailing, have led to improved prognosis for functional recovery and limb salvage. Despite improved union and limb salvage rates, the prognosis for severe type III open fracture of the tibial shaft remains guarded, and outcomes are often determined by patient psychosocial variables.

  7. Pediatric elbow fractures: a new angle on an old topic

    Energy Technology Data Exchange (ETDEWEB)

    Emery, Kathleen H.; Anton, Christopher G. [Cincinnati Children' s Hospital Medical Center, Department of Radiology, Cincinnati, OH (United States); Zingula, Shannon N. [Mayo Clinic, Department of Radiology, Rochester, MN (United States); Salisbury, Shelia R. [Cincinnati Children' s Hospital Medical Center, Biostatistics and Epidemiology, Cincinnati, OH (United States); Tamai, Junichi [Cincinnati Children' s Hospital Medical Center, Department of Pediatric Orthopedics, Cincinnati, OH (United States)

    2016-01-15

    historically described. The relatively high frequency of olecranon fractures detected on follow-up speaks to their potentially occult nature. Careful attention to these areas is warranted in children with initially normal radiographs. (orig.)

  8. Estimating the hydraulic conductivity of two-dimensional fracture networks

    Science.gov (United States)

    Leung, C. T.; Zimmerman, R. W.

    2010-12-01

    Most oil and gas reservoirs, as well as most potential sites for nuclear waste disposal, are naturally fractured. In these sites, the network of fractures will provide the main path for fluid to flow through the rock mass. In many cases, the fracture density is so high as to make it impractical to model it with a discrete fracture network (DFN) approach. For such rock masses, it would be useful to have recourse to analytical, or semi-analytical, methods to estimate the macroscopic hydraulic conductivity of the fracture network. We have investigated single-phase fluid flow through stochastically generated two-dimensional fracture networks. The centres and orientations of the fractures are uniformly distributed, whereas their lengths follow either a lognormal distribution or a power law distribution. We have considered the case where the fractures in the network each have the same aperture, as well as the case where the aperture of each fracture is directly proportional to the fracture length. The discrete fracture network flow and transport simulator NAPSAC, developed by Serco (Didcot, UK), is used to establish the “true” macroscopic hydraulic conductivity of the network. We then attempt to match this conductivity using a simple estimation method that does not require extensive computation. For our calculations, fracture networks are represented as networks composed of conducting segments (bonds) between nodes. Each bond represents the region of a single fracture between two adjacent intersections with other fractures. We assume that the bonds are arranged on a kagome lattice, with some fraction of the bonds randomly missing. The conductance of each bond is then replaced with some effective conductance, Ceff, which we take to be the arithmetic mean of the individual conductances, averaged over each bond, rather than over each fracture. This is in contrast to the usual approximation used in effective medium theories, wherein the geometric mean is used. Our

  9. Hip Fractures among Older Adults

    Science.gov (United States)

    ... online training for health care providers. Learn More Hip Fractures Among Older Adults Recommend on Facebook Tweet Share ... get older. What You Can Do to Prevent Hip Fractures You can prevent hip fractures by taking steps ...

  10. Bending fracture in carbon nanotubes.

    Science.gov (United States)

    Kuo, Wen-Shyong; Lu, Hsin-Fang

    2008-12-10

    A novel approach was adopted to incur bending fracture in carbon nanotubes (CNTs). Expanded graphite (EG) was made by intercalating and exfoliating natural graphite flakes. The EG was deposited with nickel particles, from which CNTs were grown by chemical vapor deposition. The CNTs were tip-grown, and their roots were fixed on the EG flakes. The EG flakes were compressed, and many CNTs on the surface were fragmented due to the compression-induced bending. Two major modes of the bending fracture were observed: cone-shaped and shear-cut. High-resolution scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the crack growth within the graphene layers. The bending fracture is characterized by two-region crack growth. An opening crack first appears around the outer-tube due to the bending-induced tensile stress. The crack then branches to grow along an inclined direction toward the inner-tube due to the presence of the shear stress in between graphene layers. An inner-tube pullout with inclined side surface is formed. The onset and development of the crack in these two regions are discussed.

  11. The Potential Impacts of Hydraulic Fracturing on Agriculture

    National Research Council Canada - National Science Library

    Beng Ong

    2014-01-01

    Hydraulic fracturing (or “fracking”) is a method of extracting oil and natural gas trapped in deep rock layers underground by pumping water, sand, and other chemicals/additives at high pressures into a well drilled vertically...

  12. Treatment of osteoporotic vertebral compression fractures

    NARCIS (Netherlands)

    Klazen, C.A.H.

    2010-01-01

    In Chapter I, an outline of this thesis is given. In Chapter 2 we prospectively determined the natural course of pain in patients with conservatively treated acute osteoporotic vertebral compression fractures (VCF). In addition, we assessed the type of conservative therapy that these patients receiv

  13. Mortality analysis in hip fracture patients

    DEFF Research Database (Denmark)

    Foss, N B; Kehlet, H

    2005-01-01

    Patients with hip fractures are usually frail and elderly with a 30-day mortality in excess of 10% in European series. Perioperative morbidity is often multifactorial in nature, and unimodal interventions will not necessarily decrease mortality. The purpose of this prospective study was to analys...

  14. Pneumothorax complicating isolated clavicle fracture.

    Science.gov (United States)

    Hani, Redouane; Ennaciri, Badr; Jeddi, Idriss; El Bardouni, Ahmed; Mahfoud, Mustapha; Berrada, Mohamed Saleh

    2015-01-01

    Isolated clavicle fractures are among the commonest of traumatic fractures in the emergency department. Complications of isolated clavicle fractures are rare. Pneumothorax has been described as a complication of a fractured clavicle only rarely in English literature. In all the reported cases, the pneumothorax was treated by a thoracostomy and the clavicle fracture was treated conservatively. In our case, the pneumothorax required a chest drain insertion and the clavicle fracture was treated surgically with good result.

  15. Hydraulic Properties of Fractured Rock Samples at In-Situ Conditions - Insights from Lab Experiments Using X-Ray Tomography

    Science.gov (United States)

    Nehler, Mathias; Stöckhert, Ferdinand; Duda, Mandy; Renner, Jörg; Bracke, Rolf

    2017-04-01

    The hydraulic properties of low-porosity rock formations are controlled by the geometry of open fractures, joints and faults. Aperture, surface roughness, accessible length, and thus, the volume available for fluids associated of such interfaces are strongly affected by their state of stress. Moreover, these properties may evolve with time in particular due to processes involving chemically active fluids. Understanding the physico-chemical interactions of rocks with fluids at reservoir conditions will help to predict the long-term reservoir development and to increase the efficiency of geothermal power plants. We designed an x-ray transparent flow-through cell. Confining pressure can be up to 50 MPa and pore fluid can currently be circulated through the sample with pressures of up to 25 MPa. All wetted parts are made of PEEK to avoid corrosion when using highly saline fluids. Laboratory experiments were performed to investigate hydraulic properties of fractured low-porosity samples under reservoir conditions while x-rays transmit the sample. The cell is placed inside a µCT scanner with a 225 kV multifocal x-ray tube for high resolution x-ray tomography. Samples measure 10 mm in diameter and 25 mm in length resulting in a voxel resolution of approximately 10 µm. Samples with single natural as well as artificial fractures were subjected to various confining pressures ranging from 2.5 MPa to 25 MPa. At each pressure level, effective permeability was determined from steady-state flow relying on Darcy's law. In addition, a full 3D image was recorded by the µCT scanner to gain information on the fracture aperture and geometry. Subvolumes (400x400x400 voxels) of the images were analyzed to reduce computational cost. The subvolumes were filtered in 3D with an edge preserving non-local means filter. Further quantification algorithms were implemented in Matlab. Segmentation into pore space and minerals was done automatically for all datasets by a peak finder algorithm

  16. Surgical menopause and nonvertebral fracture risk among older US women.

    Science.gov (United States)

    Vesco, Kimberly K; Marshall, Lynn M; Nelson, Heidi D; Humphrey, Linda; Rizzo, Joanne; Pedula, Kathryn L; Cauley, Jane A; Ensrud, Kristine E; Hochberg, Marc C; Antoniucci, Diana; Hillier, Teresa A

    2012-05-01

    The aim of this study was to determine whether older postmenopausal women with a history of bilateral oophorectomy before natural menopause (surgical menopause) have a higher risk of nonvertebral postmenopausal fracture than women with natural menopause. We used 21 years of prospectively collected incident fracture data from the ongoing Study of Osteoporotic Fractures, a cohort study of community-dwelling women without previous bilateral hip fracture who were 65 years or older at enrollment, to determine the risk of hip, wrist, and any nonvertebral fracture. χ(2) and t tests were used to compare the two groups on important characteristics. Multivariable Cox proportional hazards regression models stratified by baseline oral estrogen use status were used to estimate the risk of fracture. Baseline characteristics differed significantly among the 6,616 women within the Study of Osteoporotic Fractures who underwent either surgical (1,157) or natural (5,459) menopause, including mean age at menopause (44.3 ± 7.4 vs 48.9 ± 4.9 y, P menopause, even among women who had never used oral estrogen (hip fracture: hazard ratio [HR], 0.87; 95% CI, 0.63-1.21; wrist fracture: HR, 1.10; 95% CI, 0.78-1.57; any nonvertebral fracture: HR, 1.11; 95% CI, 0.93-1.32). These data provide some reassurance that the long-term risk of nonvertebral fracture is not substantially increased for postmenopausal women who experienced premenopausal bilateral oophorectomy, compared with postmenopausal women with intact ovaries, even in the absence of postmenopausal estrogen therapy.

  17. Fractures and stresses in Bone Spring sandstones

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, J.C.; Warpinski, N.R.; Sattler, A.R.; Northrop, D.A.

    1990-09-01

    This project is a collaboration between Sandia National Laboratories and Harvey E. Yates Company being conducted under the auspices of the Oil Recovery Technology Partnership. The project seeks to apply perspectives related to the effects of natural fractures, stress, and sedimentology to the simulation and production of low-permeability gas reservoirs to low-permeability oil reservoirs as typified by the Bone Spring sandstones of the Permian Basin, southeast New Mexico. This report presents the results and analysis obtained in 1989 from 233 ft of oriented core, comprehensive suite of logs, various in situ stress measurements, and detailed well tests conducted in conjunction with the drilling of two development wells. Natural fractures were observed in core and logs in the interbed carbonates, but there was no direct evidence of fractures in the sandstones. However, production tests of the sandstones indicated permeabilities and behavior typical of a dual porosity reservoir. A general northeast trend for the maximum principal horizontal stress was observed in an elastic strain recovery measurements and in strikes of drilling-induced fractures; this direction is subparallel to the principal fracture trend observed in the interbed carbonates. Many of the results presented are believed to be new information for the Bone Spring sandstones. 57 figs., 18 tabs.

  18. Connection Strings Property on ADO Connection Object

    Institute of Scientific and Technical Information of China (English)

    Girigi Deogratias; Wu Min; Cao Weihua

    2002-01-01

    The connection string property on ADO connection object contains the information used to establish a connection to the data source. The syntax, the keyword of that information must be in specific format. Depending on the type of data you are connecting to, you need either specify an OLEDB provider or use on ODBC driver. The biggest problem, the industries face is the proliferation of data access interfaces, and the complexity of creating,maintaining and programming against them, and the network problem when communicating over the Intranet or the Internet. This paper first provides an in-depth look of the standard arguments supported by ADO connection string; then gives the easier way for understanding the meaning, the utility and the syntax of the connection strings property on ADO connection object, and finally proposes solution to work around the problems due to the connection strings errors.

  19. Vertebral Fracture Prediction

    DEFF Research Database (Denmark)

    2008-01-01

    Vertebral Fracture Prediction A method of processing data derived from an image of at least part of a spine is provided for estimating the risk of a future fracture in vertebraeof the spine. Position data relating to at least four neighbouring vertebrae of the spine is processed. The curvature...

  20. Radial head fracture - aftercare

    Science.gov (United States)

    ... Philadelphia, PA: Elsevier Saunders; 2015:chap 6. Prawer A. Radius and ulna fractures. In: Eiff M, Hatch R, eds. Fracture Management for Primary Care . 3rd ed. Philadelphia, PA: Elsevier Saunders; 2012:chap ... PhD, and the A.D.A.M. Editorial team. Related MedlinePlus Health ...

  1. Displaced patella fractures.

    Science.gov (United States)

    Della Rocca, Gregory J

    2013-10-01

    Displaced patella fractures often result in disruption of the extensor mechanism of the knee. An intact extensor mechanism is a requirement for unassisted gait. Therefore, operative treatment of the displaced patella fracture is generally recommended. The evaluation of the patella fracture patient includes examination of extensor mechanism integrity. Operative management of patella fractures normally includes open reduction with internal fixation, although partial patellectomy is occasionally performed, with advancement of quadriceps tendon or patellar ligament to the fracture bed. Open reduction with internal fixation has historically been performed utilizing anterior tension band wiring, although comminution of the fracture occasionally makes this fixation construct inadequate. Supplementation or replacement of the tension band wire construct with interfragmentary screws, cerclage wire or suture, and/or plate-and-screw constructs may add to the stability of the fixation construct. Arthrosis of the patellofemoral joint is very common after healing of patella fractures, and substantial functional deficits may persist long after fracture healing has occurred. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  2. THORACIC SPINE FRACTURES

    Institute of Scientific and Technical Information of China (English)

    戴力扬

    2001-01-01

    Objective. To investigate the unique characteristics and treatment of thoracic spine fractures.Methods. Severty-seven patients with thoracic spine fractures were retrospectively reviewed. Of these, therewere 37 compressior fractures, 34 fracture-dislocations, 3 burst fractures and 3 burst-dislocations. Twenty-six pa-tients had a complete lesion of the spinal cord, 14 sustained a neurologically incomplete injury, and 37 wereneurologically intact. Fifty-three patients were treated nonoperatively and 24 treated operatively.Results. All patients were followed up for 2 ~ 15 years. None of the 26 patients with a complete lesion recov-ered any significant function. Of 37 neurologically intact patients, 13 had local pain although all of them re-mained normal function. Two of 14 patients with incomplete paraplegia returned to normal, 7 recovered some func-tion and 5 did not recovered.Conclusions. E ecause of the unique anatomy and biomechanics of the thoracic spine, the classification common-ly applied to thoracolumbar fractures is not suitable for thoracic fractures. Fusion and instrumentation are indicat-ed when the fractures are unstable, while patients with incomplete lesion of the spinal cord may be the candidatesfor supplemented decompression.

  3. Fractured-basement reservoir modeling using continuous fracture modeling (CFM) method

    Science.gov (United States)

    Isniarny, Nadya; Haris, Abdul; Nurdin, Safrizal

    2016-02-01

    The challenge in oil and gas exploration has now shifted due to increasingly difficult to get back up economic value in a conventional reservoir. Explorationist are developing various drilling technology, optimizing conventional reserves and unconventional reserve in reservoirs. One of the unconventional reservoir that has been developed is the basement reservoir. This rock type has no primary porosity and the permeability of the rocks of this type are generally influenced by the naturally fracture networks. The purpose of this study is to map the fracture intensity distribution in the basement reservoir using Continuous Fracture Modeling (CFM) method. CFM method applies the basic concepts of neural network in finding a relationship between well data with seismic data in order to build a model of fracture intensity. The Formation Micro Imager (FMI) interpretation data is used to identify the presence of fracture along the well as dip angle and dip azimuth. This indicator will be laterally populated in 3D grid model. Several seismic attribute which are generated from seismic data is used as a guidance to populate fracture intensity in the model. The results from the model were validated with Drill Stem Test (DST) data. Zones of high fracture intensity on the model correlates positively with the presence of fluid in accordance with DST data.

  4. Rapid imbibition of water in fractures within unsaturated sedimentary rock

    Science.gov (United States)

    Cheng, C.-L.; Perfect, E.; Donnelly, B.; Bilheux, H. Z.; Tremsin, A. S.; McKay, L. D.; DiStefano, V. H.; Cai, J. C.; Santodonato, L. J.

    2015-03-01

    The spontaneous imbibition of water and other liquids into gas-filled fractures in variably-saturated porous media is important in a variety of engineering and geological contexts. However, surprisingly few studies have investigated this phenomenon. We present a theoretical framework for predicting the 1-dimensional movement of water into air-filled fractures within a porous medium based on early-time capillary dynamics and spreading over the rough surfaces of fracture faces. The theory permits estimation of sorptivity values for the matrix and fracture zone, as well as a dispersion parameter which quantifies the extent of spreading of the wetting front. Quantitative data on spontaneous imbibition of water in unsaturated Berea sandstone cores were acquired to evaluate the proposed model. The cores with different permeability classes ranging from 50 to 500 mD and were fractured using the Brazilian method. Spontaneous imbibition in the fractured cores was measured by dynamic neutron radiography at the Neutron Imaging Prototype Facility (beam line CG-1D, HFIR), Oak Ridge National Laboratory. Water uptake into both the matrix and the fracture zone exhibited square-root-of-time behavior. The matrix sorptivities ranged from 2.9 to 4.6 mm s-0.5, and increased linearly as the permeability class increased. The sorptivities of the fracture zones ranged from 17.9 to 27.1 mm s-0.5, and increased linearly with increasing fracture aperture width. The dispersion coefficients ranged from 23.7 to 66.7 mm2 s-1 and increased linearly with increasing fracture aperture width and damage zone width. Both theory and observations indicate that fractures can significantly increase spontaneous imbibition in unsaturated sedimentary rock by capillary action and surface spreading on rough fracture faces. Fractures also increase the dispersion of the wetting front. Further research is needed to investigate this phenomenon in other natural and engineered porous media.

  5. Transphyseal Distal Humerus Fracture.

    Science.gov (United States)

    Abzug, Joshua; Ho, Christine Ann; Ritzman, Todd F; Brighton, Brian

    2016-01-01

    Transphyseal distal humerus fractures typically occur in children younger than 3 years secondary to birth trauma, nonaccidental trauma, or a fall from a small height. Prompt and accurate diagnosis of a transphyseal distal humerus fracture is crucial for a successful outcome. Recognizing that the forearm is not aligned with the humerus on plain radiographs may aid in the diagnosis of a transphyseal distal humerus fracture. Surgical management is most commonly performed with the aid of an arthrogram. Closed reduction and percutaneous pinning techniques similar to those used for supracondylar humerus fractures are employed. Cubitus varus caused by a malunion, osteonecrosis of the medial condyle, or growth arrest is the most common complication encountered in the treatment of transphyseal distal humerus fractures. A corrective lateral closing wedge osteotomy can be performed to restore a nearly normal carrying angle.

  6. Galeazzi