Changing the scale of hydrogeophysical aquifer heterogeneity characterization

Science.gov (United States)

Paradis, Daniel; Tremblay, Laurie; Ruggeri, Paolo; Brunet, Patrick; Fabien-Ouellet, Gabriel; Gloaguen, Erwan; Holliger, Klaus; Irving, James; Molson, John; Lefebvre, Rene

2015-04-01

Contaminant remediation and management require the quantitative predictive capabilities of groundwater flow and mass transport numerical models. Such models have to encompass source zones and receptors, and thus typically cover several square kilometers. To predict the path and fate of contaminant plumes, these models have to represent the heterogeneous distribution of hydraulic conductivity (K). However, hydrogeophysics has generally been used to image relatively restricted areas of the subsurface (small fractions of km2), so there is a need for approaches defining heterogeneity at larger scales and providing data to constrain conceptual and numerical models of aquifer systems. This communication describes a workflow defining aquifer heterogeneity that was applied over a 12 km2 sub-watershed surrounding a decommissioned landfill emitting landfill leachate. The aquifer is a shallow, 10 to 20 m thick, highly heterogeneous and anisotropic assemblage of littoral sand and silt. Field work involved the acquisition of a broad range of data: geological, hydraulic, geophysical, and geochemical. The emphasis was put on high resolution and continuous hydrogeophysical data, the use of direct-push fully-screened wells and the acquisition of targeted high-resolution hydraulic data covering the range of observed aquifer materials. The main methods were: 1) surface geophysics (ground-penetrating radar and electrical resistivity); 2) direct-push operations with a geotechnical drilling rig (cone penetration tests with soil moisture resistivity CPT/SMR; full-screen well installation); and 3) borehole operations, including high-resolution hydraulic tests and geochemical sampling. New methods were developed to acquire high vertical resolution hydraulic data in direct-push wells, including both vertical and horizontal K (Kv and Kh). Various data integration approaches were used to represent aquifer properties in 1D, 2D and 3D. Using relevant vector machines (RVM), the mechanical and

Assessment of managed aquifer recharge at Sand Hollow Reservoir, Washington County, Utah, updated to conditions through 2007

Science.gov (United States)

Heilweil, Victor M.; Ortiz, Gema; Susong, David D.

2009-01-01

Sand Hollow Reservoir in Washington County, Utah, was completed in March 2002 and is operated primarily as an aquifer storage and recovery project by the Washington County Water Conservancy District (WCWCD). Since its inception in 2002 through 2007, surface-water diversions of about 126,000 acre-feet to Sand Hollow Reservoir have resulted in a generally rising reservoir stage and surface area. Large volumes of runoff during spring 2005-06 allowed the WCWCD to fill the reservoir to a total storage capacity of more than 50,000 acre-feet, with a corresponding surface area of about 1,300 acres and reservoir stage of about 3,060 feet during 2006. During 2007, reservoir stage generally decreased to about 3,040 feet with a surface-water storage volume of about 30,000 acre-feet. Water temperature in the reservoir shows large seasonal variation and has ranged from about 3 to 30 deg C from 2003 through 2007. Except for anomalously high recharge rates during the first year when the vadose zone beneath the reservoir was becoming saturated, estimated ground-water recharge rates have ranged from 0.01 to 0.09 feet per day. Estimated recharge volumes have ranged from about 200 to 3,500 acre-feet per month from March 2002 through December 2007. Total ground-water recharge during the same period is estimated to have been about 69,000 acre-feet. Estimated evaporation rates have varied from 0.04 to 0.97 feet per month, resulting in evaporation losses of 20 to 1,200 acre-feet per month. Total evaporation from March 2002 through December 2007 is estimated to have been about 25,000 acre-feet. Results of water-quality sampling at monitoring wells indicate that by 2007, managed aquifer recharge had arrived at sites 37 and 36, located 60 and 160 feet from the reservoir, respectively. However, different peak arrival dates for specific conductance, chloride, chloride/bromide ratios, dissolved oxygen, and total dissolved-gas pressures at each monitoring well indicate the complicated nature of

Numerical simulation of groundwater movement and managed aquifer recharge from Sand Hollow Reservoir, Hurricane Bench area, Washington County, Utah

Science.gov (United States)

Marston, Thomas M.; Heilweil, Victor M.

2012-01-01

The Hurricane Bench area of Washington County, Utah, is a 70 square-mile area extending south from the Virgin River and encompassing Sand Hollow basin. Sand Hollow Reservoir, located on Hurricane Bench, was completed in March 2002 and is operated primarily as a managed aquifer recharge project by the Washington County Water Conservancy District. The reservoir is situated on a thick sequence of the Navajo Sandstone and Kayenta Formation. Total recharge to the underlying Navajo aquifer from the reservoir was about 86,000 acre-feet from 2002 to 2009. Natural recharge as infiltration of precipitation was approximately 2,100 acre-feet per year for the same period. Discharge occurs as seepage to the Virgin River, municipal and irrigation well withdrawals, and seepage to drains at the base of reservoir dams. Within the Hurricane Bench area, unconfined groundwater-flow conditions generally exist throughout the Navajo Sandstone. Navajo Sandstone hydraulic-conductivity values from regional aquifer testing range from 0.8 to 32 feet per day. The large variability in hydraulic conductivity is attributed to bedrock fractures that trend north-northeast across the study area.A numerical groundwater-flow model was developed to simulate groundwater movement in the Hurricane Bench area and to simulate the movement of managed aquifer recharge from Sand Hollow Reservoir through the groundwater system. The model was calibrated to combined steady- and transient-state conditions. The steady-state portion of the simulation was developed and calibrated by using hydrologic data that represented average conditions for 1975. The transient-state portion of the simulation was developed and calibrated by using hydrologic data collected from 1976 to 2009. Areally, the model grid was 98 rows by 76 columns with a variable cell size ranging from about 1.5 to 25 acres. Smaller cells were used to represent the reservoir to accurately simulate the reservoir bathymetry and nearby monitoring wells; larger

Seismic Modeling Of Reservoir Heterogeneity Scales: An Application To Gas Hydrate Reservoirs

Science.gov (United States)

Huang, J.; Bellefleur, G.; Milkereit, B.

2008-12-01

Natural gas hydrates, a type of inclusion compound or clathrate, are composed of gas molecules trapped within a cage of water molecules. The occurrence of gas hydrates in permafrost regions has been confirmed by core samples recovered from the Mallik gas hydrate research wells located within Mackenzie Delta in Northwest Territories of Canada. Strong vertical variations of compressional and shear sonic velocities and weak surface seismic expressions of gas hydrates indicate that lithological heterogeneities control the distribution of hydrates. Seismic scattering studies predict that typical scales and strong physical contrasts due to gas hydrate concentration will generate strong forward scattering, leaving only weak energy captured by surface receivers. In order to understand the distribution of hydrates and the seismic scattering effects, an algorithm was developed to construct heterogeneous petrophysical reservoir models. The algorithm was based on well logs showing power law features and Gaussian or Non-Gaussian probability density distribution, and was designed to honor the whole statistical features of well logs such as the characteristic scales and the correlation among rock parameters. Multi-dimensional and multi-variable heterogeneous models representing the same statistical properties were constructed and applied to the heterogeneity analysis of gas hydrate reservoirs. The petrophysical models provide the platform to estimate rock physics properties as well as to study the impact of seismic scattering, wave mode conversion, and their integration on wave behavior in heterogeneous reservoirs. Using the Biot-Gassmann theory, the statistical parameters obtained from Mallik 5L-38, and the correlation length estimated from acoustic impedance inversion, gas hydrate volume fraction in Mallik area was estimated to be 1.8%, approximately 2x108 m3 natural gas stored in a hydrate bearing interval within 0.25 km2 lateral extension and between 889 m and 1115 m depth

Characterizing flow pathways in a sandstone aquifer: Tectonic vs sedimentary heterogeneities

Science.gov (United States)

Medici, G.; West, L. J.; Mountney, N. P.

2016-11-01

Sandstone aquifers are commonly assumed to represent porous media characterized by a permeable matrix. However, such aquifers may be heavy fractured when rock properties and timing of deformation favour brittle failure and crack opening. In many aquifer types, fractures associated with faults, bedding planes and stratabound joints represent preferential pathways for fluids and contaminants. In this paper, well test and outcrop-scale studies reveal how strongly lithified siliciclastic rocks may be entirely dominated by fracture flow at shallow depths (≤ 180 m), similar to limestone and crystalline aquifers. However, sedimentary heterogeneities can primarily control fluid flow where fracture apertures are reduced by overburden pressures or mineral infills at greater depths. The Triassic St Bees Sandstone Formation (UK) of the East Irish Sea Basin represents an optimum example for study of the influence of both sedimentary and tectonic aquifer heterogeneities in a strongly lithified sandstone aquifer-type. This fluvial sedimentary succession accumulated in rapidly subsiding basins, which typically favours preservation of complete depositional cycles including fine grained layers (mudstone and silty sandstone) interbedded in sandstone fluvial channels. Additionally, vertical joints in the St Bees Sandstone Formation form a pervasive stratabound system whereby joints terminate at bedding discontinuities. Additionally, normal faults are present through the succession showing particular development of open-fractures. Here, the shallow aquifer (depth ≤ 180 m) was characterized using hydro-geophysics. Fluid temperature, conductivity and flow-velocity logs record inflows and outflows from normal faults, as well as from pervasive bed-parallel fractures. Quantitative flow logging analyses in boreholes that cut fault planes indicate that zones of fault-related open fractures characterize 50% of water flow. The remaining flow component is dominated by bed-parallel fractures

Accounting for the Decreasing Reaction Potential of Heterogeneous Aquifers in a Stochastic Framework of Aquifer-Scale Reactive Transport

Science.gov (United States)

Loschko, Matthias; Wöhling, Thomas; Rudolph, David L.; Cirpka, Olaf A.

2018-01-01

Many groundwater contaminants react with components of the aquifer matrix, causing a depletion of the aquifer's reactivity with time. We discuss conceptual simplifications of reactive transport that allow the implementation of a decreasing reaction potential in reactive-transport simulations in chemically and hydraulically heterogeneous aquifers without relying on a fully explicit description. We replace spatial coordinates by travel-times and use the concept of relative reactivity, which represents the reaction-partner supply from the matrix relative to a reference. Microorganisms facilitating the reactions are not explicitly modeled. Solute mixing is neglected. Streamlines, obtained by particle tracking, are discretized in travel-time increments with variable content of reaction partners in the matrix. As exemplary reactive system, we consider aerobic respiration and denitrification with simplified reaction equations: Dissolved oxygen undergoes conditional zero-order decay, nitrate follows first-order decay, which is inhibited in the presence of dissolved oxygen. Both reactions deplete the bioavailable organic carbon of the matrix, which in turn determines the relative reactivity. These simplifications reduce the computational effort, facilitating stochastic simulations of reactive transport on the aquifer scale. In a one-dimensional test case with a more detailed description of the reactions, we derive a potential relationship between the bioavailable organic-carbon content and the relative reactivity. In a three-dimensional steady-state test case, we use the simplified model to calculate the decreasing denitrification potential of an artificial aquifer over 200 years in an ensemble of 200 members. We demonstrate that the uncertainty in predicting the nitrate breakthrough in a heterogeneous aquifer decreases with increasing scale of observation.

Effects of a Reservoir Water on the GW Quality in a Coastal Aquifer of Semi-arid Region, North-east of Tunisia

Science.gov (United States)

Uchida, C.; Kawachi, A.; Tsujimura, M.; Tarhouni, J.

2015-12-01

This study investigated effects of a reservoir water in a salinized shallow aquifer based on spatial distribution of geochemical properties in groundwater (GW). In many coastal shallow aquifers of arid and semi-arid regions, groundwater table (GWT) depression and salinization have occurred due to GW overexploitation. In Korba aquifer, north-east of Tunisia, after a dam reservoir has been constructed in order to assure a water resource for irrigation, improvement of GW level and quality have been observed in the downstream area of the dam (area-A), while the GW in the other area (area-B) still has high salinity. This study, therefore, aimed to investigate the effects of the reservoir water on the GW quality. In June 2013, water quality survey and sampling were carried out at 60 wells (GW), a dam reservoir, river and the sea. Major ions, boron, bromide, and oxygen-18 and deuterium in collected samples were analyzed. From the results, in the area-B, the GWT was lower than the sea level and the high salinity were observed. The Br- concentration of the GW was correlated with the Cl- concentration, and the values of B/Cl- and Br-/Cl- of the GW were similar to the seawater. Since the GWT depression allowed the seawater to intrude into the aquifer, the GW salinization occurred in this area. On the other hand, in the area-A, GWT was higher than the seawater level, and the Na+ and Cl- concentrations were lower than the area-B. Especially, in the irrigated areas by using the reservoir water, the isotopic values, B/Cl- and Br-/Cl- of the GW were relatively higher than the others. The reservoir water has high isotopic values due to evaporation effect, and the B/Cl- and Br-/Cl- values become higher due to organic matters in sediment of the reservoir or soil in the filtration process. Thus, in addition to the direct infiltration from the reservoir into the aquifer, irrigation using a reservoir water probably has a positive impact on the GW quality in this area.

On-farm irrigation reservoirs for surface water storage in eastern Arkansas: Trends in construction in response to aquifer depletion

Science.gov (United States)

Yaeger, M. A.; Reba, M. L.; Massey, J. H.; Adviento-Borbe, A.

2017-12-01

On-farm surface water storage reservoirs have been constructed to address declines in the Mississippi River Valley Alluvial aquifer, the primary source of irrigation for most of the row crops grown in eastern Arkansas. These reservoirs and their associated infrastructure represent significant investments in financial and natural resources, and may cause producers to incur costs associated with foregone crop production and long-term maintenance. Thus, an analysis of reservoir construction trends in the Grand Prairie Critical Groundwater Area (GPCGA) and Cache River Critical Groundwater Area (CRCGA) was conducted to assist future water management decisions. Between 1996 and 2015, on average, 16 and 4 reservoirs were constructed per year, corresponding to cumulative new reservoir surface areas of 161 and 60 ha yr-1, for the GPCGA and the CRCGA, respectively. In terms of reservoir locations relative to aquifer status, after 1996, 84.5% of 309 total reservoirs constructed in the GPCGA and 91.0% of 78 in the CRCGA were located in areas with remaining saturated aquifer thicknesses of 50% or less. The majority of new reservoirs (74% in the GPCGA and 63% in the CRCGA) were constructed on previously productive cropland. The next most common land use, representing 11% and 15% of new reservoirs constructed in the GPCGA and CRCGA, respectively, was the combination of a field edge and a ditch, stream, or other low-lying area. Less than 10% of post-1996 reservoirs were constructed on predominately low-lying land, and the use of such lands decreased in both critical groundwater areas during the past 20 years. These disparities in reservoir construction rates, locations, and prior land uses is likely due to groundwater declines being first observed in the GPCGA as well as the existence of two large-scale river diversion projects under construction in the GPCGA that feature on-farm storage as a means to offset groundwater use.

Discrete Feature Approach for Heterogeneous Reservoir Production Enhancement

Energy Technology Data Exchange (ETDEWEB)

Dershowitz, William S.; Curran, Brendan; Einstein, Herbert; LaPointe, Paul; Shuttle, Dawn; Klise, Kate

2002-07-26

The report presents summaries of technology development for discrete feature modeling in support of the improved oil recovery (IOR) for heterogeneous reservoirs. In addition, the report describes the demonstration of these technologies at project study sites.

SEISMIC DETERMINATION OF RESERVOIR HETEROGENEITY: APPLICATION TO THE CHARACTERIZATION OF HEAVY OIL RESERVOIRS

Energy Technology Data Exchange (ETDEWEB)

Matthias G. Imhof; James W. Castle

2005-02-01

The objective of the project was to examine how seismic and geologic data can be used to improve characterization of small-scale heterogeneity and their parameterization in reservoir models. The study focused on West Coalinga Field in California. The project initially attempted to build reservoir models based on different geologic and geophysical data independently using different tools, then to compare the results, and ultimately to integrate them all. We learned, however, that this strategy was impractical. The different data and tools need to be integrated from the beginning because they are all interrelated. This report describes a new approach to geostatistical modeling and presents an integration of geology and geophysics to explain the formation of the complex Coalinga reservoir.

Evaluation of aquifer heterogeneity effects on river flow loss using a transition probability framework

Science.gov (United States)

Engdahl, N.B.; Vogler, E.T.; Weissmann, G.S.

2010-01-01

River-aquifer exchange is considered within a transition probability framework along the Rio Grande in Albuquerque, New Mexico, to provide a stochastic estimate of aquifer heterogeneity and river loss. Six plausible hydrofacies configurations were determined using categorized drill core and wetland survey data processed through the TPROGS geostatistical package. A base case homogeneous model was also constructed for comparison. River loss was simulated for low, moderate, and high Rio Grande stages and several different riverside drain stage configurations. Heterogeneity effects were quantified by determining the mean and variance of the K field for each realization compared to the root-mean-square (RMS) error of the observed groundwater head data. Simulation results showed that the heterogeneous models produced smaller estimates of loss than the homogeneous approximation. Differences between heterogeneous and homogeneous model results indicate that the use of a homogeneous K in a regional-scale model may result in an overestimation of loss but comparable RMS error. We find that the simulated river loss is dependent on the aquifer structure and is most sensitive to the volumetric proportion of fines within the river channel. Copyright 2010 by the American Geophysical Union.

Estimating the Spatial Extent of Unsaturated Zones in Heterogeneous River-Aquifer Systems

Science.gov (United States)

Schilling, Oliver S.; Irvine, Dylan J.; Hendricks Franssen, Harrie-Jan; Brunner, Philip

2017-12-01

The presence of unsaturated zones at the river-aquifer interface has large implications on numerous hydraulic and chemical processes. However, the hydrological and geological controls that influence the development of unsaturated zones have so far only been analyzed with simplified conceptualizations of flow processes, or homogeneous conceptualizations of the hydraulic conductivity in either the aquifer or the riverbed. We systematically investigated the influence of heterogeneous structures in both the riverbed and the aquifer on the development of unsaturated zones. A stochastic 1-D criterion that takes both riverbed and aquifer heterogeneity into account was developed using a Monte Carlo sampling technique. The approach allows the reliable estimation of the upper bound of the spatial extent of unsaturated areas underneath a riverbed. Through systematic numerical modeling experiments, we furthermore show that horizontal capillary forces can reduce the spatial extent of unsaturated zones under clogged areas. This analysis shows how the spatial structure of clogging layers and aquifers influence the propensity for unsaturated zones to develop: In riverbeds where clogged areas are made up of many small, spatially disconnected patches with a diameter in the order of 1 m, unsaturated areas are less likely to develop compared to riverbeds where large clogged areas exist adjacent to unclogged areas. A combination of the stochastic 1-D criterion with an analysis of the spatial structure of the clogging layers and the potential for resaturation can help develop an appropriate conceptual model and inform the choice of a suitable numerical simulator for river-aquifer systems.

A Review of the Multilevel Slug Test for Characterizing Aquifer Heterogeneity

Directory of Open Access Journals (Sweden)

Chia-Shyun Chen

2012-01-01

Full Text Available All aquifers are heterogeneous to a certain degree. The spatial distribution of hydraulic conductivity K(x, y, z, or aquifer heterogeneity, significantly influences the groundwater flow movement and associated solute transport. Of particular importance in designing an in-situ remediation plan is a knowledge of low-K layers because they are less accessible to remedial agents and form a bottleneck in remediation. The characterization of aquifer heterogeneity is essential to the solution of many practical and scientific groundwater problems. This article reviews the field technique using the multilevel slug test (MLST, which determines a series of K estimates at depths of interest in a well by making use of a double-packer system. The K(z obtained manifests the vertical variation of hydraulic conductivity in the vicinity of the test well, and the combination of K(z from different wells gives rise to a three-dimensional description of K(x, y, z. The MLST response is rather sensitive to hydraulic conductivity variation; e.g., it is oscillatory for highly permeable conditions (K > 5 × 10-4 m s-1 and a nonoscillatory for K < 5 × 10-4 m s-1. In this article we discuss the instrumentation of the double-packer system, the implementation of the depth-specific slug test, the data analysis methods for a spectrum of response characteristics usually observed in the field, and field applications of the MLST.

Reservoir heterogeneity in carboniferous sandstone of the Black Warrior basin. Final report

Energy Technology Data Exchange (ETDEWEB)

Kugler, R.L.; Pashin, J.C.; Carroll, R.E.; Irvin, G.D.; Moore, H.E.

1994-06-01

Although oil production in the Black Warrior basin of Alabama is declining, additional oil may be produced through improved recovery strategies, such as waterflooding, chemical injection, strategic well placement, and infill drilling. High-quality characterization of reservoirs in the Black Warrior basin is necessary to utilize advanced technology to recover additional oil and to avoid premature abandonment of fields. This report documents controls on the distribution and producibility of oil from heterogeneous Carboniferous reservoirs in the Black Warrior basin of Alabama. The first part of the report summarizes the structural and depositional evolution of the Black Warrior basin and establishes the geochemical characteristics of hydrocarbon source rocks and oil in the basin. This second part characterizes facies heterogeneity and petrologic and petrophysical properties of Carter and Millerella sandstone reservoirs. This is followed by a summary of oil production in the Black Warrior basin and an evaluation of seven improved-recovery projects in Alabama. In the final part, controls on the producibility of oil from sandstone reservoirs are discussed in terms of a scale-dependent heterogeneity classification.

Reservoir heterogeneity in Carboniferous sandstone of the Black Warrior basin. Final report

Energy Technology Data Exchange (ETDEWEB)

Kugler, R.L.; Pashin, J.C.; Carroll, R.E.; Irvin, G.D.; Moore, H.E.

1994-04-01

Although oil production in the Black Warrior basin of Alabama is declining, additional oil may be produced through improved recovery strategies, such as waterflooding, chemical injection, strategic well placement, and infill drilling. High-quality characterization of reservoirs in the Black Warrior basin is necessary to utilize advanced technology to recover additional oil and to avoid premature abandonment of fields. This report documents controls on the distribution and producibility of oil from heterogeneous Carboniferous reservoirs in the Black Warrior basin of Alabama. The first part of the report summarizes the structural and depositional evolution of the Black Warrior basin and establishes the geochemical characteristics of hydrocarbon source rocks and oil in the basin. This second part characterizes facies heterogeneity and petrologic and petrophysical properties of Carter and Millerella sandstone reservoirs. This is followed by a summary of oil production in the Black Warrior basin and an evaluation of seven improved-recovery projects in Alabama. In the final part, controls on the producibility of oil from sandstone reservoirs are discussed in terms of a scale-dependent heterogeneity classification.

Nominal Range Sensitivity Analysis of peak radionuclide concentrations in randomly heterogeneous aquifers

International Nuclear Information System (INIS)

Cadini, F.; De Sanctis, J.; Cherubini, A.; Zio, E.; Riva, M.; Guadagnini, A.

2012-01-01

Highlights: ► Uncertainty quantification problem associated with the radionuclide migration. ► Groundwater transport processes simulated within a randomly heterogeneous aquifer. ► Development of an automatic sensitivity analysis for flow and transport parameters. ► Proposal of a Nominal Range Sensitivity Analysis approach. ► Analysis applied to the performance assessment of a nuclear waste repository. - Abstract: We consider the problem of quantification of uncertainty associated with radionuclide transport processes within a randomly heterogeneous aquifer system in the context of performance assessment of a near-surface radioactive waste repository. Radionuclide migration is simulated at the repository scale through a Monte Carlo scheme. The saturated groundwater flow and transport equations are then solved at the aquifer scale for the assessment of the expected radionuclide peak concentration at a location of interest. A procedure is presented to perform the sensitivity analysis of this target environmental variable to key parameters that characterize flow and transport processes in the subsurface. The proposed procedure is exemplified through an application to a realistic case study.

Three-dimensional imaging of aquifer and aquitard heterogeneity via transient hydraulic tomography at a highly heterogeneous field site

Science.gov (United States)

Zhao, Zhanfeng; Illman, Walter A.

2018-04-01

Previous studies have shown that geostatistics-based transient hydraulic tomography (THT) is robust for subsurface heterogeneity characterization through the joint inverse modeling of multiple pumping tests. However, the hydraulic conductivity (K) and specific storage (Ss) estimates can be smooth or even erroneous for areas where pumping/observation densities are low. This renders the imaging of interlayer and intralayer heterogeneity of highly contrasting materials including their unit boundaries difficult. In this study, we further test the performance of THT by utilizing existing and newly collected pumping test data of longer durations that showed drawdown responses in both aquifer and aquitard units at a field site underlain by a highly heterogeneous glaciofluvial deposit. The robust performance of the THT is highlighted through the comparison of different degrees of model parameterization including: (1) the effective parameter approach; (2) the geological zonation approach relying on borehole logs; and (3) the geostatistical inversion approach considering different prior information (with/without geological data). Results reveal that the simultaneous analysis of eight pumping tests with the geostatistical inverse model yields the best results in terms of model calibration and validation. We also find that the joint interpretation of long-term drawdown data from aquifer and aquitard units is necessary in mapping their full heterogeneous patterns including intralayer variabilities. Moreover, as geological data are included as prior information in the geostatistics-based THT analysis, the estimated K values increasingly reflect the vertical distribution patterns of permeameter-estimated K in both aquifer and aquitard units. Finally, the comparison of various THT approaches reveals that differences in the estimated K and Ss tomograms result in significantly different transient drawdown predictions at observation ports.

Scale-up of miscible flood processes for heterogeneous reservoirs. Second annual report

Energy Technology Data Exchange (ETDEWEB)

Orr, F.M. Jr.

1995-03-01

Progress is reported for a comprehensive investigation of the scaling behavior of gas injection processes in heterogeneous reservoirs. The interplay of phase behavior, viscous fingering, gravity segregation, capillary imbibition and drainage, and reservoir heterogeneity is examined in a series of simulations and experiments. Use of streamtube to model multiphase flow is demonstrated to be a fast and accurate approach for displacements that are dominated by reservoir heterogeneity. The streamtube technique is particularly powerful for multiphase compositional displacements because it represents the effects of phase behavior with a one-dimensional flow and represents the effects of heterogeneity through the locations of streamtubes. A new approach for fast calculations of critical tie-lines directly from criticality conditions is reported. A global triangular structure solution for four-component flow systems, whose tie-lies meet at the edge of a quaternary phase diagram or lie in planes is presented. Also demonstrated is the extension of this solution to multicomponent systems under the same assumptions. The interplay of gravity, capillary and viscous forces on final residual oil saturation is examined experimentally and theoretically. The analysis of vertical equilibrium conditions for three-phase gravity drainage shows that almost all oil can be recovered from the top part of a reservoir. The prediction of spreading and stability of thin film is performed to investigate three-phase gravity drainage mechanisms. Finally, experimental results from gravity drainage of crude oil in the presence of CO{sub 2} suggest that gravity drainage could be an efficient oil recovery process for vertically fractured reservoirs.

Multiple recharge processes to heterogeneous Mediterranean coastal aquifers and implications on recharge rates evolution in time

Science.gov (United States)

Santoni, S.; Huneau, F.; Garel, E.; Celle-Jeanton, H.

2018-04-01

Climate change is nowadays widely considered to have major effects on groundwater resources. Climatic projections suggest a global increase in evaporation and higher frequency of strong rainfall events especially in Mediterranean context. Since evaporation is synonym of low recharge conditions whereas strong rainfall events are more favourable to recharge in heterogeneous subsurface contexts, a lack of knowledge remains then on the real ongoing and future drinking groundwater supply availability at aquifers scale. Due to low recharge potential and high inter-annual climate variability, this issue is strategic for the Mediterranean hydrosystems. This is especially the case for coastal aquifers because they are exposed to seawater intrusion, sea-level rise and overpumping risks. In this context, recharge processes and rates were investigated in a Mediterranean coastal aquifer with subsurface heterogeneity located in Southern Corsica (France). Aquifer recharge rates from combining ten physical and chemical methods were computed. In addition, hydrochemical and isotopic investigations were carried out through a monthly two years monitoring combining major ions and stable isotopes of water in rain, runoff and groundwater. Diffuse, focused, lateral mountain system and irrigation recharge processes were identified and characterized. A predominant focused recharge conditioned by subsurface heterogeneity is evidenced in agreement with variable but highly favourable recharge rates. The fast water transfer from the surface to the aquifer implied by this recharge process suggests less evaporation, which means higher groundwater renewal and availability in such Mediterranean coastal aquifers.

The influence of reservoir heterogeneities on geothermal doublet performance

NARCIS (Netherlands)

Doddema, Leon

2012-01-01

SUMMARY The current main problem with deep geothermal energy in the Netherlands is the uncertainty in terms of attainable flow rate and life time. The goal of this research is therefore modeling a geothermal doublet in a heterogeneous reservoir, using a

Use of time series and harmonic constituents of tidal propagation to enhance estimation of coastal aquifer heterogeneity

Science.gov (United States)

Hughes, Joseph D.; White, Jeremy T.; Langevin, Christian D.

2010-01-01

A synthetic two‐dimensional model of a horizontally and vertically heterogeneous confined coastal aquifer system, based on the Upper Floridan aquifer in south Florida, USA, subjected to constant recharge and a complex tidal signal was used to generate 15‐minute water‐level data at select locations over a 7‐day simulation period.   “Observed” water‐level data were generated by adding noise, representative of typical barometric pressure variations and measurement errors, to 15‐minute data from the synthetic model. Permeability was calibrated using a non‐linear gradient‐based parameter inversion approach with preferred‐value Tikhonov regularization and 1) “observed” water‐level data, 2) harmonic constituent data, or 3) a combination of “observed” water‐level and harmonic constituent data.    In all cases, high‐frequency data used in the parameter inversion process were able to characterize broad‐scale heterogeneities; the ability to discern fine‐scale heterogeneity was greater when harmonic constituent data were used.  These results suggest that the combined use of highly parameterized‐inversion techniques and high frequency time and/or processed‐harmonic constituent water‐level data could be a useful approach to better characterize aquifer heterogeneities in coastal aquifers influenced by ocean tides.

Some new hydraulic and tracer measurement techniques for heterogeneous aquifer formations

International Nuclear Information System (INIS)

Ptak, T.; Teutsch, G.

1990-01-01

Groundwater contamination assessment and remediation activities demand reliable techniques for the determination of the governing aquifer parameters and their spatial distribution. In order to define guidelines and recommendations, some existing underground investigation techniques were tested and new methods have been developed as a part of the research program at the Horkheimer Insel experimental field site. In this paper, some new developed field and laboratory techniques are introduced and the results compared for two example monitoring wells located in the northern part of the field site. It is shown that highly conductive and highly heterogeneous aquifers demand high resolution investigation techniques. For transport predictions, new methods are needed that are able to detect preferential flow paths. Results from multilevel tracer tests show that simple analytical interpretations are not valid for this type of aquifer. (Author) (8 refs., 12 figs., tab.)

Modelling and monitoring of Aquifer Thermal Energy Storage : impacts of soil heterogeneity, thermal interference and bioremediation

NARCIS (Netherlands)

Sommer, W.T.

2015-01-01

Modelling and monitoring of Aquifer Thermal Energy Storage

Impacts of heterogeneity, thermal interference and bioremediation

Wijbrand Sommer
PhD thesis, Wageningen University, Wageningen, NL (2015)
ISBN 978-94-6257-294-2

Abstract

Aquifer

Enhancement of wadi recharge using dams coupled with aquifer storage and recovery wells

KAUST Repository

Missimer, Thomas M. M.

2014-06-25

Wadi channel recharge to the underlying alluvial aquifer is naturally limited by the flashy nature of flood events, evapotranspiration losses of water from the vadose zone, and aquifer heterogeneity, particularly low vertical hydraulic conductivity. Anthropogenic lowering of the water table in many wadi aquifers has also reduced the potential recharge by increasing the thickness of the vadose zone, causing interflow water loss from surface emergence and evaporation. A method to enhance recharge is to slow the flow within wadi channels by placement of dam structures, thereby ponding water and increasing the vertical head gradient to create a more rapid rate of infiltration and percolation. Effectiveness of wadi dams to enhance aquifer recharge reduces over time due to mud deposition within the reservoir caused by storm events. Up to 80 % of the water in old wadi reservoirs is lost to free-surface evaporation before infiltration and recharge can occur. One method to maintain or increase the rate of recharge is to convey clean water by gravity flow from the reservoir down-gradient to artificially recharge the aquifer using existing wells. This type of system is a low-cost and low-energy recharge method which could greatly enhance groundwater storage in wadi aquifers. Modeling results show that existing wells could store up to 1,000 m3/day under gravity-feed conditions and up to 3,900 m3/day with the shut-in of the well to produce a pressurized system. © 2014 Springer-Verlag Berlin Heidelberg.

Lithology-dependent In Situ Stress in Heterogeneous Carbonate Reservoirs

Science.gov (United States)

Pham, C. N.; Chang, C.

2017-12-01

Characterization of in situ stress state for various geomechanical aspects in petroleum development may be particularly difficult in carbonate reservoirs in which rock properties are generally heterogeneous. We demonstrate that the variation of in situ stress in highly heterogeneous carbonate reservoirs is closely related to the heterogeneity in rock mechanical property. The carbonate reservoir studied consists of numerous sequential layers gently folded, exhibiting wide ranges of porosity (0.01 - 0.29) and Young's modulus (25 - 85 GPa) depending on lithology. Wellbore breakouts and drilling-induced tensile fractures (DITFs) observed in the image logs obtained from several wells indicate that the in situ state of stress orientation changes dramatically with depth and location. Even in a wellbore, the azimuth of the maximum horizontal stress changes by as much as 60° within a depth interval of 500 m. This dramatic change in stress orientation is inferred to be due to the contrast in elastic properties between different rock layers which are bent by folding in the reservoir. The horizontal principal stress magnitudes are constrained by back-calculating stress conditions necessary to induce the observed wellbore failures using breakout width and the presence of DITFs. The horizontal stresses vary widely, which cannot be represented by a constant stress gradient with depth. The horizontal principal stress gradient increases with Young's modulus of layer monotonically, indicating that a stiffer layer conveys a higher horizontal stress. This phenomenon can be simulated using a numerical modelling, in which the horizontal stress magnitudes depend on stiffness of individual layers although the applied far-field stress conditions are constant. The numerical results also suggest that the stress concentration at the wellbore wall is essentially higher in a stiffer layer, promoting the possibility of wellbore breakout formation. These results are in agreement with our

Well-based stable carbon isotope leakage monitoring of an aquifer overlying the CO2 storage reservoir at the Ketzin pilot site, Germany

Science.gov (United States)

Nowak, Martin; Myrttinen, Anssi; Zimmer, Martin; van Geldern, Robert; Barth, Johannes A. C.

2014-05-01

At the pilot site for CO2 storage in Ketzin, a new well-based leakage-monitoring concept was established, comprising geochemical and hydraulic observations of the aquifer directly above the CO2 reservoir (Wiese et al., 2013, Nowak et al. 2013). Its purpose was to allow early detection of un-trapped CO2. Within this monitoring concept, we established a stable carbon isotope monitoring of dissolved inorganic carbon (DIC). If baseline isotope values of aquifer DIC (δ13CDIC) and reservoir CO2 (δ13CCO2) are known and distinct from each other, the δ13CDIC has the potential to serve as an an early indicator for an impact of leaked CO2 on the aquifer brine. The observation well of the overlying aquifer was equipped with an U-tube sampling system that allowed sampling of unaltered brine. The high alkaline drilling mud that was used during well drilling masked δ13CDIC values at the beginning of the monitoring campaign. However, subsequent monitoring allowed observing on-going re-equilibration of the brine, indicated by changing δ13CDIC and other geochemical values, until values ranging around -23 ‰ were reached. The latter were close to baseline values before drilling. Baselineδ13CDIC and δ13CCO2 values were used to derive a geochemical and isotope model that predicts evolution of δ13CDIC, if CO2 from the reservoir would leak into the aquifer. The model shows that equilibrium isotope fractionation would have to be considered if CO2 dissolves in the brine. The model suggests that stable carbon isotope monitoring is a suitable tool to assess the impact of injected CO2 in overlying groundwater aquifers. However, more data are required to close gaps of knowledge about fractionation behaviour within the CO2(g) - DIC system under elevated pressures and temperatures. Nowak, M., Myrttinen, A., Zimmer, M., Wiese, B., van Geldern, R., Barth, J.A.C., 2013. Well-based, Geochemical Leakage Monitoring of an Aquifer Immediately Above a CO2 Storage Reservoir by Stable Carbon

Structural control on the deep hydrogeological and geothermal aquifers related to the fractured Campanian-Miocene reservoirs of north-eastern Tunisia foreland constrained by subsurface data

Science.gov (United States)

Khomsi, Sami; Echihi, Oussema; Slimani, Naji

2012-03-01

A set of different data including high resolution seismic sections, petroleum wire-logging well data, borehole piezometry, structural cross-sections and outcrop analysis allowed us to characterise the tectonic framework, and its relationships with the deep aquifers seated in Cretaceous-Miocene deep reservoirs. The structural framework, based on major structures, controls the occurrence of deep aquifers and sub-basin aquifer distributions. Five structural domains can be defined, having different morphostructural characteristics. The northernmost domain lying on the north-south axis and Zaghouan thrust system is a domain of recharge by underflow of the different subsurface reservoirs and aquifers from outcrops of highly fractured reservoirs. On the other hand, the morphostructural configuration controls the piezometry of underground flows in the Plio-Quaternary unconfined aquifer. In the subsurface the Late Cretaceous-Miocene reservoirs are widespread with high thicknesses in many places and high porosities and connectivities especially along major fault corridors and on the crestal parts of major anticlines. Among all reservoirs, the Oligo-Miocene, detritic series are widespread and present high cumulative thicknesses. Subsurface and fieldwork outline the occurrence of 10 fractured sandy reservoirs for these series with packages having high hydrodynamic and petrophysical characteristics. These series show low salinities (maximum 5 g/l) in the northern part of the study area and will constitute an important source of drinkable water for the next generations. A regional structural cross-section is presented, compiled from all the different data sets, allowing us to define the major characteristics of the hydrogeological-hydrogeothermal sub-basins. Eight hydrogeological provinces are defined from north-west to south-east. A major thermal anomaly is clearly identified in the south-eastern part of the study area in Sfax-Sidi Il Itayem. This anomaly is possibly related to

Upscaling of permeability heterogeneities in reservoir rocks; an integrated approach

NARCIS (Netherlands)

Mikes, D.

2002-01-01

This thesis presents a hierarchical and geologically constrained deterministic approach to incorporate small-scale heterogeneities into reservoir flow simulators. We use a hierarchical structure to encompass all scales from laminae to an entire depositional system. For the geological models under

IDENTIFIABILITY VERSUS HETEROGENEITY IN GROUNDWATER MODELING SYSTEMS

Directory of Open Access Journals (Sweden)

A M BENALI

2003-06-01

Full Text Available Review of history matching of reservoirs parameters in groundwater flow raises the problem of identifiability of aquifer systems. Lack of identifiability means that there exists parameters to which the heads are insensitive. From the guidelines of the study of the homogeneous case, we inspect the identifiability of the distributed transmissivity field of heterogeneous groundwater aquifers. These are derived from multiple realizations of a random function Y = log T  whose probability distribution function is normal. We follow the identifiability of the autocorrelated block transmissivities through the measure of the sensitivity of the local derivatives DTh = (∂hi  ∕ ∂Tj computed for each sample of a population N (0; σY, αY. Results obtained from an analysis of Monte Carlo type suggest that the more a system is heterogeneous, the less it is identifiable.

Effects of reservoir heterogeneity on scaling of effective mass transfer coefficient for solute transport

Science.gov (United States)

Leung, Juliana Y.; Srinivasan, Sanjay

2016-09-01

Modeling transport process at large scale requires proper scale-up of subsurface heterogeneity and an understanding of its interaction with the underlying transport mechanisms. A technique based on volume averaging is applied to quantitatively assess the scaling characteristics of effective mass transfer coefficient in heterogeneous reservoir models. The effective mass transfer coefficient represents the combined contribution from diffusion and dispersion to the transport of non-reactive solute particles within a fluid phase. Although treatment of transport problems with the volume averaging technique has been published in the past, application to geological systems exhibiting realistic spatial variability remains a challenge. Previously, the authors developed a new procedure where results from a fine-scale numerical flow simulation reflecting the full physics of the transport process albeit over a sub-volume of the reservoir are integrated with the volume averaging technique to provide effective description of transport properties. The procedure is extended such that spatial averaging is performed at the local-heterogeneity scale. In this paper, the transport of a passive (non-reactive) solute is simulated on multiple reservoir models exhibiting different patterns of heterogeneities, and the scaling behavior of effective mass transfer coefficient (Keff) is examined and compared. One such set of models exhibit power-law (fractal) characteristics, and the variability of dispersion and Keff with scale is in good agreement with analytical expressions described in the literature. This work offers an insight into the impacts of heterogeneity on the scaling of effective transport parameters. A key finding is that spatial heterogeneity models with similar univariate and bivariate statistics may exhibit different scaling characteristics because of the influence of higher order statistics. More mixing is observed in the channelized models with higher-order continuity. It

Integration of crosswell seismic data for simulating porosity in a heterogeneous carbonate aquifer

Science.gov (United States)

Emery, Xavier; Parra, Jorge

2013-11-01

A challenge for the geostatistical simulation of subsurface properties in mining, petroleum and groundwater applications is the integration of well logs and seismic measurements, which can provide information on geological heterogeneities at a wide range of scales. This paper presents a case study conducted at the Port Mayaca aquifer, located in western Martin County, Florida, in which it is of interest to simulate porosity, based on porosity logs at two wells and high-resolution crosswell seismic measurements of P-wave impedance. To this end, porosity and impedance are transformed into cross-correlated Gaussian random fields, using local transformations. The model parameters (transformation functions, mean values and correlation structure of the transformed fields) are inferred and checked against the data. Multiple realizations of porosity can then be constructed conditionally to the impedance information in the interwell region, which allow identifying one low-porosity structure and two to three flow units that connect the two wells, mapping heterogeneities within these units and visually assessing fluid paths in the aquifer. In particular, the results suggest that the paths in the lower flow units, formed by a network of heterogeneous conduits, are not as smooth as in the upper flow unit.

IMPROVING CO2 EFFICIENCY FOR RECOVERING OIL IN HETEROGENEOUS RESERVOIRS

International Nuclear Information System (INIS)

Grigg, Reid B.

2002-01-01

A three-year contract, DOE Contract No. DE-FG26-01BC15364 ''Improving CO 2 Efficiency for Recovering Oil in Heterogeneous Reservoirs,'' was started on September 28, 2001. This project examines three major areas in which CO 2 flooding can be improved: fluid and matrix interactions, conformance control/sweep efficiency, and reservoir simulation for improved oil recovery. This report discusses the activity during the six-month period covering January 1, 2002 through June 30, 2002 that covers the second and third fiscal quarters of the project's first year. Paper SPE 75178, ''Cost Reduction and Injectivity Improvements for CO 2 Foams for Mobility Control,'' has been presented and included in the proceedings of the SPE/DOE Thirteenth Symposium on Improved Oil Recovery, Tulsa, OK, April 13-17, 2002. During these two quarters of the project we have been working in several areas: reservoir fluid/rock interactions and their relationships to changing injectivity, producer survey on injectivity, and surfactant adsorption on quarried and reservoir core

Geologic CO2 Sequestration: Predicting and Confirming Performance in Oil Reservoirs and Saline Aquifers

Science.gov (United States)

Johnson, J. W.; Nitao, J. J.; Newmark, R. L.; Kirkendall, B. A.; Nimz, G. J.; Knauss, K. G.; Ziagos, J. P.

2002-05-01

Reducing anthropogenic CO2 emissions ranks high among the grand scientific challenges of this century. In the near-term, significant reductions can only be achieved through innovative sequestration strategies that prevent atmospheric release of large-scale CO2 waste streams. Among such strategies, injection into confined geologic formations represents arguably the most promising alternative; and among potential geologic storage sites, oil reservoirs and saline aquifers represent the most attractive targets. Oil reservoirs offer a unique "win-win" approach because CO2 flooding is an effective technique of enhanced oil recovery (EOR), while saline aquifers offer immense storage capacity and widespread distribution. Although CO2-flood EOR has been widely used in the Permian Basin and elsewhere since the 1980s, the oil industry has just recently become concerned with the significant fraction of injected CO2 that eludes recycling and is therefore sequestered. This "lost" CO2 now has potential economic value in the growing emissions credit market; hence, the industry's emerging interest in recasting CO2 floods as co-optimized EOR/sequestration projects. The world's first saline aquifer storage project was also catalyzed in part by economics: Norway's newly imposed atmospheric emissions tax, which spurred development of Statoil's unique North Sea Sleipner facility in 1996. Successful implementation of geologic sequestration projects hinges on development of advanced predictive models and a diverse set of remote sensing, in situ sampling, and experimental techniques. The models are needed to design and forecast long-term sequestration performance; the monitoring techniques are required to confirm and refine model predictions and to ensure compliance with environmental regulations. We have developed a unique reactive transport modeling capability for predicting sequestration performance in saline aquifers, and used it to simulate CO2 injection at Sleipner; we are now

Characterizing Heterogeneity in Infiltration Rates During Managed Aquifer Recharge.

Science.gov (United States)

Mawer, Chloe; Parsekian, Andrew; Pidlisecky, Adam; Knight, Rosemary

2016-11-01

Infiltration rate is the key parameter that describes how water moves from the surface into a groundwater aquifer during managed aquifer recharge (MAR). Characterization of infiltration rate heterogeneity in space and time is valuable information for MAR system operation. In this study, we utilized fiber optic distributed temperature sensing (FO-DTS) observations and the phase shift of the diurnal temperature signal between two vertically co-located fiber optic cables to characterize infiltration rate spatially and temporally in a MAR basin. The FO-DTS measurements revealed spatial heterogeneity of infiltration rate: approximately 78% of the recharge water infiltrated through 50% of the pond bottom on average. We also introduced a metric for quantifying how the infiltration rate in a recharge pond changes over time, which enables FO-DTS to be used as a method for monitoring MAR and informing maintenance decisions. By monitoring this metric, we found high-spatial variability in how rapidly infiltration rate changed during the test period. We attributed this variability to biological pore clogging and found a relationship between high initial infiltration rate and the most rapid pore clogging. We found a strong relationship (R 2  = 0.8) between observed maximum infiltration rates and electrical resistivity measurements from electrical resistivity tomography data taken in the same basin when dry. This result shows that the combined acquisition of DTS and ERT data can improve the design and operation of a MAR pond significantly by providing the critical information needed about spatial variability in parameters controlling infiltration rates. © 2016, National Ground Water Association.

Analysis of structural heterogeneities on drilled cores: a reservoir modeling oriented methodology; Analyse des heterogeneites structurales sur carottes: une methodologie axee vers la modelisation des reservoirs

Energy Technology Data Exchange (ETDEWEB)

Cortes, P.; Petit, J.P. [Montpellier-2 Univ., Lab. de Geophysique, Tectonique et Sedimentologie, UMR CNRS 5573, 34 (France); Guy, L. [ELF Aquitaine Production, 64 - Pau (France); Thiry-Bastien, Ph. [Lyon-1 Univ., 69 (France)

1999-07-01

The characterization of structural heterogeneities of reservoirs is of prime importance for hydrocarbons recovery. A methodology is presented which allows to compare the dynamic behaviour of fractured reservoirs and the observation of microstructures on drilled cores or surface reservoir analogues. (J.S.)

A Semianalytical Model for Pumping Tests in Finite Heterogeneous Confined Aquifers With Arbitrarily Shaped Boundary

Science.gov (United States)

Wang, Lei; Dai, Cheng; Xue, Liang

2018-04-01

This study presents a Laplace-transform-based boundary element method to model the groundwater flow in a heterogeneous confined finite aquifer with arbitrarily shaped boundaries. The boundary condition can be Dirichlet, Neumann or Robin-type. The derived solution is analytical since it is obtained through the Green's function method within the domain. However, the numerical approximation is required on the boundaries, which essentially renders it a semi-analytical solution. The proposed method can provide a general framework to derive solutions for zoned heterogeneous confined aquifers with arbitrarily shaped boundary. The requirement of the boundary element method presented here is that the Green function must exist for a specific PDE equation. In this study, the linear equations for the two-zone and three-zone confined aquifers with arbitrarily shaped boundary is established in Laplace space, and the solution can be obtained by using any linear solver. Stehfest inversion algorithm can be used to transform it back into time domain to obtain the transient solution. The presented solution is validated in the two-zone cases by reducing the arbitrarily shaped boundaries to circular ones and comparing it with the solution in Lin et al. (2016, https://doi.org/10.1016/j.jhydrol.2016.07.028). The effect of boundary shape and well location on dimensionless drawdown in two-zone aquifers is investigated. Finally the drawdown distribution in three-zone aquifers with arbitrarily shaped boundary for constant-rate tests (CRT) and flow rate distribution for constant-head tests (CHT) are analyzed.

Mixing effects on apparent reaction rates and isotope fractionation during denitrification in a heterogeneous aquifer

Science.gov (United States)

Green, Christopher T.; Böhlke, John Karl; Bekins, Barbara A.; Phillips, Steven P.

2010-01-01

Gradients in contaminant concentrations and isotopic compositions commonly are used to derive reaction parameters for natural attenuation in aquifers. Differences between field‐scale (apparent) estimated reaction rates and isotopic fractionations and local‐scale (intrinsic) effects are poorly understood for complex natural systems. For a heterogeneous alluvial fan aquifer, numerical models and field observations were used to study the effects of physical heterogeneity on reaction parameter estimates. Field measurements included major ions, age tracers, stable isotopes, and dissolved gases. Parameters were estimated for the O2 reduction rate, denitrification rate, O2 threshold for denitrification, and stable N isotope fractionation during denitrification. For multiple geostatistical realizations of the aquifer, inverse modeling was used to establish reactive transport simulations that were consistent with field observations and served as a basis for numerical experiments to compare sample‐based estimates of “apparent” parameters with “true“ (intrinsic) values. For this aquifer, non‐Gaussian dispersion reduced the magnitudes of apparent reaction rates and isotope fractionations to a greater extent than Gaussian mixing alone. Apparent and true rate constants and fractionation parameters can differ by an order of magnitude or more, especially for samples subject to slow transport, long travel times, or rapid reactions. The effect of mixing on apparent N isotope fractionation potentially explains differences between previous laboratory and field estimates. Similarly, predicted effects on apparent O2threshold values for denitrification are consistent with previous reports of higher values in aquifers than in the laboratory. These results show that hydrogeological complexity substantially influences the interpretation and prediction of reactive transport.

Hydraulic Tomography for Estimating the Diffusivity of Heterogeneous Aquifers Based on Groundwater Response to Tidal Fluctuation in an Artificial Island in Taiwan

Directory of Open Access Journals (Sweden)

Jet-Chau Wen

2018-01-01

Full Text Available This study investigated the hydraulic properties of the heterogeneous aquifers of an artificial island (Yunlin Offshore Industrial Park in Taiwan. The research was based on the groundwater level response affected by tidal fluctuation using the hydraulic tomography (HT to analyze the hydraulic diffusivity (α. Specifically, the power spectrum ratio of groundwater and tidal fluctuations derived from the Gelhar solution was used to estimate α in homogeneous aquifers; this, however, could not be applied in the artificial island. Next, the spatial distribution of the groundwater level response affected by tidal fluctuation was analyzed and found to be irregular, proving the existence of hydrogeological heterogeneity in the artificial island. Furthermore, the results of the estimated α using the HT showed low error and high correlation, 0.41 m2/hr and 0.83, respectively, between the optimal estimated heterogeneous and reference α fields in the synthetic aquifer. Last, the HT was used in the real tested scenario. By comparing the predicted groundwater levels of the optimal estimated heterogeneous α field and the observed groundwater levels of the real aquifer, it was found that the correlation was higher than 0.99. Therefore, the HT can be used to obtain the optimal estimated heterogeneous α field in the artificial island.

Reservoir theory, groundwater transit time distributions, and lumped parameter models

International Nuclear Information System (INIS)

Etcheverry, D.; Perrochet, P.

1999-01-01

The relation between groundwater residence times and transit times is given by the reservoir theory. It allows to calculate theoretical transit time distributions in a deterministic way, analytically, or on numerical models. Two analytical solutions validates the piston flow and the exponential model for simple conceptual flow systems. A numerical solution of a hypothetical regional groundwater flow shows that lumped parameter models could be applied in some cases to large-scale, heterogeneous aquifers. (author)

Hydraulic characterization of aquifers, reservoir rocks, and soils: A history of ideas

Science.gov (United States)

Narasimhan, T. N.

1998-01-01

Estimation of the hydraulic properties of aquifers, petroleum reservoir rocks, and soil systems is a fundamental task in many branches of Earth sciences and engineering. The transient diffusion equation proposed by Fourier early in the 19th century for heat conduction in solids constitutes the basis for inverting hydraulic test data collected in the field to estimate the two basic parameters of interest, namely, hydraulic conductivity and hydraulic capacitance. Combining developments in fluid mechanics, heat conduction, and potential theory, the civil engineers of the 19th century, such as Darcy, Dupuit, and Forchheimer, solved many useful problems of steady state seepage of water. Interest soon shifted towards the understanding of the transient flow process. The turn of the century saw Buckingham establish the role of capillary potential in governing moisture movement in partially water-saturated soils. The 1920s saw remarkable developments in several branches of the Earth sciences; Terzaghi's analysis of deformation of watersaturated earth materials, the invention of the tensiometer by Willard Gardner, Meinzer's work on the compressibility of elastic aquifers, and the study of the mechanics of oil and gas reservoirs by Muskat and others. In the 1930s these led to a systematic analysis of pressure transients from aquifers and petroleum reservoirs through the work of Theis and Hurst. The response of a subsurface flow system to a hydraulic perturbation is governed by its geometric attributes as well as its material properties. In inverting field data to estimate hydraulic parameters, one makes the fundamental assumption that the flow geometry is known a priori. This approach has generally served us well in matters relating to resource development primarily concerned with forecasting fluid pressure declines. Over the past two decades, Earth scientists have become increasingly concerned with environmental contamination problems. The resolution of these problems

Quantification of oil recovery efficiency, CO 2 storage potential, and fluid-rock interactions by CWI in heterogeneous sandstone oil reservoirs

DEFF Research Database (Denmark)

Seyyedi, Mojtaba; Sohrabi, Mehran; Sisson, Adam

2017-01-01

Significant interest exists in improving recovery from oil reservoirs while addressing concerns about increasing CO2 concentrations in the atmosphere. The combination of Enhanced Oil Recovery (EOR) and safe geologic storage of CO2 in oil reservoirs is appealing and can be achieved by carbonated (CO...... for oil recovery and CO2 storage potential on heterogeneous cores. Since not all the oil reservoirs are homogenous, understanding the potential of CWI as an integrated EOR and CO2 storage scenario in heterogeneous oil reservoirs is essential....

Lithological and hydrological influences on ground-water composition in a heterogeneous carbonate-clay aquifer system

Science.gov (United States)

Kauffman, S.J.; Herman, J.S.; Jones, B.F.

1998-01-01

The influence of clay units on ground-water composition was investigated in a heterogeneous carbonate aquifer system of Miocene age in southwest Florida, known as the Intermediate aquifer system. Regionally, the ground water is recharged inland, flows laterally and to greater depths in the aquifer systems, and is discharged vertically upward at the saltwater interface along the coast. A depth profile of water composition was obtained by sampling ground water from discrete intervals within the permeable carbonate units during coring and by squeezing pore water from a core of the less-permeable clay layers. A normative salt analysis of solute compositions in the water indicated a marine origin for both types of water and an evolutionary pathway for the clay water that involves clay diagenesis. The chemical composition of the ground water in the carbonate bedrock is significantly different from that of the pore water in the clay layers. Dissolution of clays and opaline silica results in high silica concentrations relative to water in other parts of the Intermediate aquifer system. Water enriched in chloride relative to the overlying and underlying ground water recharges the aquifer inland where the confining clay layer is absent, and it dissolves carbonate and silicate minerals and reacts with clays along its flow path, eventually reaching this coastal site and resulting in the high chloride and silica concentrations observed in the middle part of the Intermediate aquifer system. Reaction-path modeling suggests that the recharging surficial water mixes with sulfate-rich water upwelling from the Upper Floridan aquifer, and carbonate mineral dissolution and precipitation, weathering and exchange reactions, clay mineral diagenesis, clay and silica dissolution, organic carbon oxidation, and iron and sulfate reduction result in the observed water compositions.A study was conducted to clarify the influence of clay units on ground-water composition in a heterogeneous

Development and Modelling of a High-Resolution Aquifer Analog in the Guarani Aquifer (Brazil)

OpenAIRE

Höyng, Dominik

2014-01-01

A comprehensive and detailed knowledge about the spatial distribution of physical and chemical properties in heterogeneous porous aquifers plays a decisive role for a realistic representation of governing parameters in mathematical models. Models allow the simulation, prediction and reproduction of subsurface flow and transport characteristics. This work explains the identification, characterization and effects of small-scale aquifer heterogeneities in the Guarani Aquifer System (GAS) in S...

on GAGD EOR in Naturally Fractured Reservoirs

Directory of Open Access Journals (Sweden)

Misagh Delalat

2013-01-01

Full Text Available The gas-assisted gravity drainage (GAGD process is designed and practiced based on gravity drainage idea and uses the advantage of density difference between injected CO2 and reservoir oil. In this work, one of Iran western oilfields was selected as a case study and a sector model was simulated based on its rock and fluid properties. The pressure of CO2 gas injection was close to the MMP of the oil, which was measured 1740 psia. Both homogeneous and heterogeneous types of fractures were simulated by creating maps of permeability and porosity. The results showed that homogeneous fractures had the highest value of efficiency, namely 40%; however, in heterogeneous fractures, the efficiency depended on the value of fracture density and the maximum efficiency was around 37%. Also, the effect of injection rate on two different intensities of fracture was studied and the results demonstrated that the model having higher fracture intensity had less limitation in increasing the CO2 injection rate; furthermore, its BHP did not increase intensively at higher injection rates either. In addition, three different types of water influxes were inspected on GAGD performance to simulate active, partial, and weak aquifer. The results showed that strong aquifer had a reverse effect on the influence of GAGD and almost completely disabled the gravity drainage mechanism. Finally, we inventively used a method to weaken the aquifer strength, and thus the gravity drainage revived and efficiency started to increase as if there was no aquifer.

Predicting Formation Damage in Aquifer Thermal Energy Storage Systems Utilizing a Coupled Hydraulic-Thermal-Chemical Reservoir Model

Science.gov (United States)

Müller, Daniel; Regenspurg, Simona; Milsch, Harald; Blöcher, Guido; Kranz, Stefan; Saadat, Ali

2014-05-01

In aquifer thermal energy storage (ATES) systems, large amounts of energy can be stored by injecting hot water into deep or intermediate aquifers. In a seasonal production-injection cycle, water is circulated through a system comprising the porous aquifer, a production well, a heat exchanger and an injection well. This process involves large temperature and pressure differences, which shift chemical equilibria and introduce or amplify mechanical processes. Rock-fluid interaction such as dissolution and precipitation or migration and deposition of fine particles will affect the hydraulic properties of the porous medium and may lead to irreversible formation damage. In consequence, these processes determine the long-term performance of the ATES system and need to be predicted to ensure the reliability of the system. However, high temperature and pressure gradients and dynamic feedback cycles pose challenges on predicting the influence of the relevant processes. Within this study, a reservoir model comprising a coupled hydraulic-thermal-chemical simulation was developed based on an ATES demonstration project located in the city of Berlin, Germany. The structural model was created with Petrel, based on data available from seismic cross-sections and wellbores. The reservoir simulation was realized by combining the capabilities of multiple simulation tools. For the reactive transport model, COMSOL Multiphysics (hydraulic-thermal) and PHREEQC (chemical) were combined using the novel interface COMSOL_PHREEQC, developed by Wissmeier & Barry (2011). It provides a MATLAB-based coupling interface between both programs. Compared to using COMSOL's built-in reactive transport simulator, PHREEQC additionally calculates adsorption and reaction kinetics and allows the selection of different activity coefficient models in the database. The presented simulation tool will be able to predict the most important aspects of hydraulic, thermal and chemical transport processes relevant to

Using solute and heat tracers for aquifer characterization in a strongly heterogeneous alluvial aquifer

Science.gov (United States)

Sarris, Theo S.; Close, Murray; Abraham, Phillip

2018-03-01

A test using Rhodamine WT and heat as tracers, conducted over a 78 day period in a strongly heterogeneous alluvial aquifer, was used to evaluate the utility of the combined observation dataset for aquifer characterization. A highly parameterized model was inverted, with concentration and temperature time-series as calibration targets. Groundwater heads recorded during the experiment were boundary dependent and were ignored during the inversion process. The inverted model produced a high resolution depiction of the hydraulic conductivity and porosity fields. Statistical properties of these fields are in very good agreement with estimates from previous studies at the site. Spatially distributed sensitivity analysis suggests that both solute and heat transport were most sensitive to the hydraulic conductivity and porosity fields and less sensitive to dispersivity and thermal distribution factor, with sensitivity to porosity greatly reducing outside the monitored area. The issues of model over-parameterization and non-uniqueness are addressed through identifiability analysis. Longitudinal dispersivity and thermal distribution factor are highly identifiable, however spatially distributed parameters are only identifiable near the injection point. Temperature related density effects became observable for both heat and solute, as the temperature anomaly increased above 12 degrees centigrade, and affected down gradient propagation. Finally we demonstrate that high frequency and spatially dense temperature data cannot inform a dual porosity model in the absence of frequent solute concentration measurements.

Element mobilization and immobilization from carbonate rocks between CO 2 storage reservoirs and the overlying aquifers during a potential CO 2 leakage

Energy Technology Data Exchange (ETDEWEB)

Lawter, Amanda R.; Qafoku, Nikolla P.; Asmussen, R. Matthew; Kukkadapu, Ravi K.; Qafoku, Odeta; Bacon, Diana H.; Brown, Christopher F.

2018-04-01

Despite the numerous studies on changes within the reservoir following CO2 injection and the effects of CO2 release into overlying aquifers, little or no literature is available on the effect of CO2 release on rock between the storage reservoirs and subsurface. To address this knowledge gap, relevant rock materials, temperatures and pressures were used to study mineralogical and elemental changes in this intermediate zone. After rocks reacted with CO2, liquid analysis showed an increase of major elements (e.g., Ca, and Mg) and variable concentrations of potential contaminants (e.g., Sr and Ba); lower concentrations were observed in N2 controls. In experiments with As/Cd and/or organic spikes, representing potential contaminants in the CO2 plume originating in the storage reservoir, most or all of these contaminants were removed from the aqueous phase. SEM and Mössbauer spectroscopy results showed the formation of new minerals and Fe oxides in some CO2-reacted samples, indicating potential for contaminant removal through mineral incorporation or adsorption onto Fe oxides. These experiments show the interactions between the CO2-laden plume and the rock between storage reservoirs and overlying aquifers have the potential to affect the level of risk to overlying groundwater, and should be considered during site selection and risk evaluation.

Prediction of Gas Injection Performance for Heterogeneous Reservoirs

Energy Technology Data Exchange (ETDEWEB)

Blunt, Martin J.; Orr, Franklin M.

1999-05-17

This report describes research carried out in the Department of Petroleum Engineering at Stanford University from September 1997 - September 1998 under the second year of a three-year grant from the Department of Energy on the "Prediction of Gas Injection Performance for Heterogeneous Reservoirs." The research effort is an integrated study of the factors affecting gas injection, from the pore scale to the field scale, and involves theoretical analysis, laboratory experiments, and numerical simulation. The original proposal described research in four areas: (1) Pore scale modeling of three phase flow in porous media; (2) Laboratory experiments and analysis of factors influencing gas injection performance at the core scale with an emphasis on the fundamentals of three phase flow; (3) Benchmark simulations of gas injection at the field scale; and (4) Development of streamline-based reservoir simulator. Each state of the research is planned to provide input and insight into the next stage, such that at the end we should have an integrated understanding of the key factors affecting field scale displacements.

Rapid heterogeneous assembly of multiple magma reservoirs prior to Yellowstone supereruptions.

Science.gov (United States)

Wotzlaw, Jörn-Frederik; Bindeman, Ilya N; Stern, Richard A; D'Abzac, Francois-Xavier; Schaltegger, Urs

2015-09-10

Large-volume caldera-forming eruptions of silicic magmas are an important feature of continental volcanism. The timescales and mechanisms of assembly of the magma reservoirs that feed such eruptions as well as the durations and physical conditions of upper-crustal storage remain highly debated topics in volcanology. Here we explore a comprehensive data set of isotopic (O, Hf) and chemical proxies in precisely U-Pb dated zircon crystals from all caldera-forming eruptions of Yellowstone supervolcano. Analysed zircons record rapid assembly of multiple magma reservoirs by repeated injections of isotopically heterogeneous magma batches and short pre-eruption storage times of 10(3) to 10(4) years. Decoupled oxygen-hafnium isotope systematics suggest a complex source for these magmas involving variable amounts of differentiated mantle-derived melt, Archean crust and hydrothermally altered shallow-crustal rocks. These data demonstrate that complex magma reservoirs with multiple sub-chambers are a common feature of rift- and hotspot related supervolcanoes. The short duration of reservoir assembly documents rapid crustal remelting and two to three orders of magnitude higher magma production rates beneath Yellowstone compared to continental arc volcanoes. The short pre-eruption storage times further suggest that the detection of voluminous reservoirs of eruptible magma beneath active supervolcanoes may only be possible prior to an impending eruption.

Reservoir characterization and final pre-test analysis in support of the compressed-air-energy-storage Pittsfield aquifer field test in Pike County, Illinois

Energy Technology Data Exchange (ETDEWEB)

Wiles, L.E.; McCann, R.A.

1983-06-01

The work reported is part of a field experimental program to demonstrate and evaluate compressed air energy storage in a porous media aquifer reservoir near Pittsfield, Illinois. The reservoir is described. Numerical modeling of the reservoir was performed concurrently with site development. The numerical models were applied to predict the thermohydraulic performance of the porous media reservoir. This reservoir characterization and pre-test analysis made use of evaluation of bubble development, water coning, thermal development, and near-wellbore desaturation. The work was undertaken to define the time required to develop an air storage bubble of adequate size, to assess the specification of instrumentation and above-ground equipment, and to develop and evaluate operational strategies for air cycling. A parametric analysis was performed for the field test reservoir. (LEW)

Field study of macrodispersion in a heterogeneous aquifer. I

International Nuclear Information System (INIS)

Boggs, J.M.; Young, S.C.; Waldrop, W.R.; Gelhar, L.W.; Adams, E.E.; Rehfeldt, K.R.

1990-01-01

A large-scale natural gradient tracer experiment has been conducted at a field site located at Columbus Air Force Base in northeastern Mississippi. The alluvial aquifer at the test site is composed of lenticular deposits of sand, gravel, silt and clay, and is quite heterogeneous with respect to its hydraulic properties. Ten cubic meters of a solution containing bromide and three organic tracers (pentafluorobenzoic acid, o-trifluoromethylbenzoic acid, and 2,6-difluorobenzoic acid) were injected into the aquifer at a uniform rate over a period of two days. The tracer plume was subsequently monitored in three dimensions over a 20-month period using a network of 258 multilevel sampling wells. The tracer concentration distribution of the plume at the conclusion of the experiment was highly asymmetric in the longitudinal direction. The peak tracer concentration was located only 7 m from the injection point, while the advancing side of the plume extended downgradient a distance of more than 260 m. The extreme skewness of the plume was caused by large scale spatial variations in the mean groundwater velocity along the plume travel path produced by the approximate two order-of-magnitude increase in the mean hydraulic conductivity between the near-field and far-field regions of the experimental site. The tracer mass balance during the experiment showed a declining trend between sampling events with approximately 50 percent of the injected tracer mass unaccounted for at the end of the experiment. Laboratory column experiments indicated that approximately 20 percent of the tracer mass was adsorbed to the aquifer matrix. The remaining 30 percent of the missing tracer mass was attributed to incomplete sampling coverage of the plume, particularly on the advancing side, and to a sampling bias produced by the multilevel samplers. (Author) (17 refs., 3 tabs., 11 figs.)

Hydrogeophysics and geochemistry reveal heterogeneity and water quality improvements in aquifer recharge and recovery (ARR) (Invited)

Science.gov (United States)

Parsekian, A.; Regnery, J.; Wing, A.; Knight, R. J.; Drewes, J. E.

2013-12-01

Aquifer recharge and recover (ARR) is the process of infiltrating water into the ground for storage and withdrawal through wells at a later time. Two significant challenges faced during the design of ARR systems are 1) evaluating aquifer heterogeneity and 2) understanding the rock fluid interactions; these knowledge gaps may have profound impacts on the volume of recoverable water and the improvement in water quality in comparison with the source-water. Our objective in this research is to leverage the advantages of hydrogeophysical measurements and geochemical sampling to reveal the properties of an aquifer through which ARR water travels with the goal of informing current operations and future design decisions. Combined geophysical and geochemical investigations reveal subsurface heterogeneity, indicate possible flow paths though the aquifer and quantify specific reductions in contaminant concentrations. Ground penetrating radar (GPR), electromagnetic induction (EMI) and electrical resistivity tomography (ERT) were used to image the subsurface throughout two key infiltration/extraction areas of an ARR site in Colorado, USA. The most valuable results came from 2.5D ERT revealing the structural patterns and suggesting the distribution of textural composition of unconsolidated sediments. Geochemical measurements on transects intersecting the geophysical measurements resolved bulk parameters (i.e. total organic carbon, cations, anions) and trace organic contaminants (e.g. trace organic compounds) and were also used to estimate mixing and water travel times and assess the performance of the ARR site regarding water quality and quantity. Our results indicate that the subsurface is highly heterogeneous at our study site and that the coarse-grained sedimentary units, acting as the best conduit for transporting water, are likely discontinuous. The electrical resistivity measurements indicate certain areas of the infiltration basins may have good hydraulic connections to

Evaluation of Microstructural Parameters of Reservoir Rocks of the Guarani Aquifer by Analysis of Images Obtained by X- Ray Microtomography

Science.gov (United States)

Fernandes, J. S.; Lima, F. A.; Vieira, S. F.; Reis, P. J.; Appoloni, C. R.

2015-07-01

Microstructural parameters evaluation of porous materials, such as, rocks reservoir (water, petroleum, gas...), it is of great importance for several knowledge areas. In this context, the X-ray microtomography (μ-CT) has been showing a technical one quite useful for the analysis of such rocks (sandstone, limestone and carbonate), object of great interest of the petroleum and water industries, because it facilitates the characterization of important parameters, among them, porosity, permeability, grains or pore size distribution. The X-ray microtomography is a non-destructive method, that besides already facilitating the reuse of the samples analyzed, it also supplies images 2-D and 3-D of the sample. In this work samples of reservoir rock of the Guarani aquifer will be analyzed, given by the company of perforation of wells artesian Blue Water, in the municipal district of Videira, Santa Catarina, Brazil. The acquisition of the microtomographys data of the reservoir rocks was accomplished in a Skyscan 1172 μ-CT scanner, installed in Applied Nuclear Physics Laboratory (LFNA) in the State University of Londrina (UEL), Paraná, Brazil. In this context, this work presents the microstructural characterization of reservoir rock sample of the Guarani aquifer, analyzed for two space resolutions, 2.8 μm and 4.8 μm, where determined average porosity was 28.5% and 21.9%, respectively. Besides, we also determined the pore size distribution for both resolutions. Two 3-D images were generated of this sample, one for each space resolution, in which it is possible to visualize the internal structure of the same ones.

Evaluation of Microstructural Parameters of Reservoir Rocks of the Guarani Aquifer by Analysis of Images Obtained by X- Ray Microtomography

International Nuclear Information System (INIS)

Fernandes, J S; Lima, F A; Vieira, S F; Reis, P J; Appoloni, C R

2015-01-01

Microstructural parameters evaluation of porous materials, such as, rocks reservoir (water, petroleum, gas...), it is of great importance for several knowledge areas. In this context, the X-ray microtomography (μ-CT) has been showing a technical one quite useful for the analysis of such rocks (sandstone, limestone and carbonate), object of great interest of the petroleum and water industries, because it facilitates the characterization of important parameters, among them, porosity, permeability, grains or pore size distribution. The X-ray microtomography is a non-destructive method, that besides already facilitating the reuse of the samples analyzed, it also supplies images 2-D and 3-D of the sample. In this work samples of reservoir rock of the Guarani aquifer will be analyzed, given by the company of perforation of wells artesian Blue Water, in the municipal district of Videira, Santa Catarina, Brazil. The acquisition of the microtomographys data of the reservoir rocks was accomplished in a Skyscan 1172 μ-CT scanner, installed in Applied Nuclear Physics Laboratory (LFNA) in the State University of Londrina (UEL), Paraná, Brazil. In this context, this work presents the microstructural characterization of reservoir rock sample of the Guarani aquifer, analyzed for two space resolutions, 2.8 μm and 4.8 μm, where determined average porosity was 28.5% and 21.9%, respectively. Besides, we also determined the pore size distribution for both resolutions. Two 3-D images were generated of this sample, one for each space resolution, in which it is possible to visualize the internal structure of the same ones. (paper)

Measurements of capillary pressure and electric permittivity of gas-water systems in porous media at elevated pressures : Application to geological storage of CO2 in aquifers and wetting behavior in coal

NARCIS (Netherlands)

Plug, W.J.

2007-01-01

Sequestration of CO2 in aquifers and coal layers is a promising technique to reduce greenhouse gas emissions. Considering the reservoir properties, e.g. wettability, heterogeneity and the caprocks sealing capacity, the capillary pressure is an important measure to evaluate the efficiency, the

Geostatistical Simulation of Hydrofacies Heterogeneity of the West Thessaly Aquifer Systems in Greece

International Nuclear Information System (INIS)

Modis, K.; Sideri, D.

2013-01-01

Integrating geological properties, such as relative positions and proportions of different hydrofacies, is of highest importance in order to render realistic geological patterns. Sequential indicator simulation (SIS) and Plurigaussian simulation (PS) are alternative methods for conceptual and deterministic modeling for the characterization of hydrofacies distribution. In this work, we studied the spatial differentiation of hydrofacies in the alluvial aquifer system of West Thessaly basin in Greece. For this, we applied both SIS and PS techniques to an extensive set of borehole data from that basin. Histograms of model versus experimental hydrofacies proportions and indicative cross sections were plotted in order to validate the results. The PS technique was shown to be more effective in reproducing the spatial characteristics of the different hydrofacies and their distribution across the study area. In addition, the permeability differentiations reflected in the PS model are in accordance to known heterogeneities of the aquifer capacity.

Geostatistical Simulation of Hydrofacies Heterogeneity of the West Thessaly Aquifer Systems in Greece

Energy Technology Data Exchange (ETDEWEB)

Modis, K., E-mail: kmodis@mail.ntua.gr; Sideri, D. [National Technical University of Athens, School of Mining and Metallurgical Engineering (Greece)

2013-06-15

Integrating geological properties, such as relative positions and proportions of different hydrofacies, is of highest importance in order to render realistic geological patterns. Sequential indicator simulation (SIS) and Plurigaussian simulation (PS) are alternative methods for conceptual and deterministic modeling for the characterization of hydrofacies distribution. In this work, we studied the spatial differentiation of hydrofacies in the alluvial aquifer system of West Thessaly basin in Greece. For this, we applied both SIS and PS techniques to an extensive set of borehole data from that basin. Histograms of model versus experimental hydrofacies proportions and indicative cross sections were plotted in order to validate the results. The PS technique was shown to be more effective in reproducing the spatial characteristics of the different hydrofacies and their distribution across the study area. In addition, the permeability differentiations reflected in the PS model are in accordance to known heterogeneities of the aquifer capacity.

Improved Efficiency of Miscible CO2 Floods and Enhanced Prospects for CO2 Flooding Heterogeneous Reservoirs

Energy Technology Data Exchange (ETDEWEB)

Grigg, Reid B.; Schechter, David S.

1999-10-15

The goal of this project is to improve the efficiency of miscible CO2 floods and enhance the prospects for flooding heterogeneous reservoirs. This report provides results of the second year of the three-year project that will be exploring three principles: (1) Fluid and matrix interactions (understanding the problems). (2) Conformance control/sweep efficiency (solving the problems. 3) Reservoir simulation for improved oil recovery (predicting results).

Impacts of physical and chemical aquifer heterogeneity on basin-scale solute transport: Vulnerability of deep groundwater to arsenic contamination in Bangladesh

Science.gov (United States)

Michael, Holly A.; Khan, Mahfuzur R.

2016-12-01

Aquifer heterogeneity presents a primary challenge in predicting the movement of solutes in groundwater systems. The problem is particularly difficult on very large scales, across which permeability, chemical properties, and pumping rates may vary by many orders of magnitude and data are often sparse. An example is the fluvio-deltaic aquifer system of Bangladesh, where naturally-occurring arsenic (As) exists over tens of thousands of square kilometers in shallow groundwater. Millions of people in As-affected regions rely on deep (≥150 m) groundwater as a safe source of drinking water. The sustainability of this resource has been evaluated with models using effective properties appropriate for a basin-scale contamination problem, but the extent to which preferential flow affects the timescale of downward migration of As-contaminated shallow groundwater is unknown. Here we embed detailed, heterogeneous representations of hydraulic conductivity (K), pumping rates, and sorptive properties (Kd) within a basin-scale numerical groundwater flow and solute transport model to evaluate their effects on vulnerability and deviations from simulations with homogeneous representations in two areas with different flow systems. Advective particle tracking shows that heterogeneity in K does not affect average travel times from shallow zones to 150 m depth, but the travel times of the fastest 10% of particles decreases by a factor of ∼2. Pumping distributions do not strongly affect travel times if irrigation remains shallow, but increases in the deep pumping rate substantially reduce travel times. Simulation of advective-dispersive transport with sorption shows that deep groundwater is protected from contamination over a sustainable timeframe (>1000 y) if the spatial distribution of Kd is uniform. However, if only low-K sediments sorb As, 30% of the aquifer is not protected. Results indicate that sustainable management strategies in the Bengal Basin should consider impacts of both

Scale-up of miscible flood processes for heterogeneous reservoirs. 1993 annual report

Energy Technology Data Exchange (ETDEWEB)

Orr, F.M. Jr.

1994-05-01

Progress is reported for a comprehensive investigation of the scaling behavior of gas injection processes in heterogeneous reservoirs. The interplay of phase behavior, viscous fingering, gravity segregation, capillary imbibition and drainage, and reservoir heterogeneity is examined in a series of simulations and experiments. Compositional and first-contact miscable simulations of viscous fingering and gravity segregation are compared to show that the two techniques can give very different results. Also, analyzed are two-dimensional and three-dimensional flows in which gravity segregation and viscous fingering interact. The simulations show that 2D and 3D flows can differ significantly. A comparison of analytical solutions for three-component two-phase flow with experimental results for oil/water/alcohol systems is reported. While the experiments and theory show reasonable agreement, some differences remain to be explained. The scaling behavior of the interaction of gravity segregation and capillary forces is investigated through simulations and through scaling arguments based on analysis of the differential equations. The simulations show that standard approaches do not agree well with results of low IFT displacements. The scaling analyses, however, reveal flow regimes where capillary, gravity, or viscous forces dominate the flow.

An Integrated Rock Typing Approach for Unraveling the Reservoir Heterogeneity of Tight Sands in the Whicher Range Field of Perth Basin, Western Australia

DEFF Research Database (Denmark)

Ilkhchi, Rahim Kadkhodaie; Rezaee, Reza; Harami, Reza Moussavi

2014-01-01

Tight gas sands in Whicher Range Field of Perth Basin show large heterogeneity in reservoir characteristics and production behavior related to depositional and diagenetic features. Diagenetic events (compaction and cementation) have severely affected the pore system. In order to investigate...... the petrophysical characteristics, reservoir sandstone facies were correlated with core porosity and permeability and their equivalent well log responses to describe hydraulic flow units and electrofacies, respectively. Thus, very tight, tight, and sub-tight sands were differentiated. To reveal the relationship...... between pore system properties and depositional and diagenetic characteristics in each sand type, reservoir rock types were extracted. The identified reservoir rock types are in fact a reflection of internal reservoir heterogeneity related to pore system properties. All reservoir rock types...

Approaches to identifying reservoir heterogeneity and reserve growth opportunities from subsurface data: The Oficina Formation, Budare field, Venezuela

Energy Technology Data Exchange (ETDEWEB)

Hamilton, D.S.; Raeuchle, S.K.; Holtz, M.H. [Bureau of Economic Geology, Austin, TX (United States)] [and others

1997-08-01

We applied an integrated geologic, geophysical, and engineering approach devised to identify heterogeneities in the subsurface that might lead to reserve growth opportunities in our analysis of the Oficina Formation at Budare field, Venezuela. The approach involves 4 key steps: (1) Determine geologic reservoir architecture; (2) Investigate trends in reservoir fluid flow; (3) Integrate fluid flow trends with reservoir architecture; and (4) Estimate original oil-in-place, residual oil saturation, and remaining mobile oil, to identify opportunities for reserve growth. There are three main oil-producing reservoirs in the Oficina Formation that were deposited in a bed-load fluvial system, an incised valley-fill, and a barrier-strandplain system. Reservoir continuity is complex because, in addition to lateral facies variability, the major Oficina depositional systems were internally subdivided by high-frequency stratigraphic surfaces. These surfaces define times of intermittent lacustrine and marine flooding events that punctuated the fluvial and marginal marine sedimentation, respectively. Syn and post depositional faulting further disrupted reservoir continuity. Trends in fluid flow established from initial fluid levels, response to recompletion workovers, and pressure depletion data demonstrated barriers to lateral and vertical fluid flow caused by a combination of reservoir facies pinchout, flooding shale markers, and the faults. Considerable reserve growth potential exists at Budare field because the reservoir units are highly compartment by the depositional heterogeneity and structural complexity. Numerous reserve growth opportunities were identified in attics updip of existing production, in untapped or incompletely drained compartments, and in field extensions.

Aquifer Storage Recovery (ASR) of chlorinated municipal drinking water in a confined aquifer

Science.gov (United States)

Izbicki, John A.; Petersen, Christen E.; Glotzbach, Kenneth J.; Metzger, Loren F.; Christensen, Allen H.; Smith, Gregory A.; O'Leary, David R.; Fram, Miranda S.; Joseph, Trevor; Shannon, Heather

2010-01-01

About 1.02 x 106 m3 of chlorinated municipal drinking water was injected into a confined aquifer, 94-137 m below Roseville, California, between December 2005 and April 2006. The water was stored in the aquifer for 438 days, and 2.64 x 106 m3 of water were extracted between July 2007 and February 2008. On the basis of Cl data, 35% of the injected water was recovered and 65% of the injected water and associated disinfection by-products (DBPs) remained in the aquifer at the end of extraction. About 46.3 kg of total trihalomethanes (TTHM) entered the aquifer with the injected water and 37.6 kg of TTHM were extracted. As much as 44 kg of TTHMs remained in the aquifer at the end of extraction because of incomplete recovery of injected water and formation of THMs within the aquifer by reactions with freechlorine in the injected water. Well-bore velocity log data collected from the Aquifer Storage Recovery (ASR) well show as much as 60% of the injected water entered the aquifer through a 9 m thick, high-permeability layer within the confined aquifer near the top of the screened interval. Model simulations of ground-water flow near the ASR well indicate that (1) aquifer heterogeneity allowed injected water to move rapidly through the aquifer to nearby monitoring wells, (2) aquifer heterogeneity caused injected water to move further than expected assuming uniform aquifer properties, and (3) physical clogging of high-permeability layers is the probable cause for the observed change in the distribution of borehole flow. Aquifer heterogeneity also enhanced mixing of native anoxic ground water with oxic injected water, promoting removal of THMs primarily through sorption. A 3 to 4-fold reduction in TTHM concentrations was observed in the furthest monitoring well 427 m downgradient from the ASR well, and similar magnitude reductions were observed in depth-dependent water samples collected from the upper part of the screened interval in the ASR well near the end of the extraction

The limited role of aquifer heterogeneity on metal reduction in an Atlantic coastal plain determined by push-pull tests

International Nuclear Information System (INIS)

Mailloux, Brian J.; Devlin, Stephanie; Fuller, Mark E.; Onstott, T.C.; De Flaun, Mary F.; Choi, K.-H.; Green-Blum, Maria; Swift, Donald J.P.; McCarthy, John; Dong Hailiang

2007-01-01

Sixty push-pull experiments were conducted to determine the factors controlling Fe(III) and Mn(IV) reduction in a well-characterized, shallow, coastal plain aquifer near Oyster, VA, USA. The five multi-level samplers each equipped with 12 ports sampled a heterogeneous portion of the aquifer from 4.4 to 8m-bgs. Each multi-level sampler (MLS) was injected with groundwater that contained NO 3 - and Br - along with: (1) just groundwater (control treatment), (2) humics, (3) lactate (conducted twice) and (4) lactate plus humics. Microbially mediated Fe(III) reduction caused the aqueous Fe Tot concentrations to increase at every depth in the lactate treatment with significant increases within 1 day even while NO 3 - was present. Little change in the Fe Tot concentrations were observed in the control and humics treatment. Humics may have acted as an electron shuttle to increase Fe(III) reduction in the lactate plus humics treatment. The amount of Mn(IV) reduction was significantly lower than that of Fe(III) reduction. Geochemical modeling indicated that gas formation, sorption on reactive surfaces, and mineral precipitation were important processes and that Fe(III) and SO 4 2- reduction were co-occurring. Conditions were favorable for the precipitation of Fe-carbonates, Fe-sulfides and Fe-silicates. In the lactate treatment protist concentrations increased then decreased and planktonic cell concentrations steadily increased, whereas no change was observed in the control treatment. Correlations of Fe(III) reduction with physical and chemical heterogeneity were weak, probably as a result of the abundance of Fe(III) bearing minerals relative to electron donor abundance and that the push-pull test sampled a representative elemental volume that encompassed the microbial diversity within the aquifer. This work indicates that stimulating metal reduction in aquifer systems is a feasible method for remediating heterogeneous subsurface sites contaminated with metals and

IMPROVING CO2 EFFICIENCY FOR RECOVERING OIL IN HETEROGENEOUS RESERVOIRS

International Nuclear Information System (INIS)

Reid B. Grigg; Robert K. Svec; Zheng-Wen Zeng; Liu Yi; Baojun Bai

2004-01-01

A three-year contract for the project, DOE Contract No. DE-FG26-01BC15364, ''Improving CO 2 Efficiency for Recovering Oil in Heterogeneous Reservoirs'', was started on September 28, 2001. This project examines three major areas in which CO 2 flooding can be improved: fluid and matrix interactions, conformance control/sweep efficiency, and reservoir simulation for improved oil recovery. The project has received a one-year, no-cost extension to September 27, 2005. During this extra time additional deliverables will be (1) the version of MASTER that has been debugged and a foam option added for CO 2 mobility control and (2) adsorption/desorption data on pure component minerals common in reservoir rock that will be used to improve predictions of chemical loss to adsorption in reservoirs. This report discusses the activity during the six-month period covering October 1, 2003 through March 31, 2004 that comprises the first and second fiscal quarters of the project's third year. During this period of the project several areas have advanced: reservoir fluid/rock interactions and their relationships to changing injectivity, and surfactant adsorption on quarried core and pure component granules, foam stability, and high flow rate effects. Presentations and papers included: a papers covered in a previous report was presented at the fall SPE ATCE in Denver in October 2003, a presentation at the Southwest ACS meeting in Oklahoma City, presentation on CO 2 flood basic behavior at the Midland Annual CO 2 Conference December 2003; two papers prepared for the biannual SPE/DOE Symposium on IOR, Tulsa, April 2004; one paper accepted for the fall 2004 SPE ATCE in Houston; and a paper submitted to an international journal Journal of Colloid and Interface Science which is being revised after peer review

Model-based analysis of δ34S signatures to trace sedimentary pyrite oxidation during managed aquifer recharge in a heterogeneous aquifer

Science.gov (United States)

Seibert, Simone; Descourvieres, Carlos; Skrzypek, Grzegorz; Deng, Hailin; Prommer, Henning

2017-05-01

The oxidation of pyrite is often one of the main drivers affecting groundwater quality during managed aquifer recharge in deep aquifers. Data and techniques that allow detailed identification and quantification of pyrite oxidation are therefore crucial for assessing and predicting the adverse water quality changes that may be associated with this process. In this study, we explore the benefits of combining stable sulphur isotope analysis with reactive transport modelling to improve the identification and characterisation of pyrite oxidation during an aquifer storage and recovery experiment in a chemically and physically heterogeneous aquifer. We characterise the stable sulphur isotope signal (δ34S) in both the ambient groundwater and the injectant as well as its spatial distribution within the sedimentary sulphur species. The identified stable sulphur isotope signal for pyrite was found to vary between -32 and +34‰, while the signal of the injectant ranged between +9.06 and +14.45‰ during the injection phase of the experiment. Both isotope and hydrochemical data together suggest a substantial contribution of pyrite oxidation to the observed, temporally variable δ34S signals. The variability of the δ34S signal in pyrite and the injectant were both found to complicate the analysis of the stable isotope data. However, the incorporation of the data into a numerical modelling approach allowed to successfully employ the δ34S signatures as a valuable additional constraint for identifying and quantifying the contribution of pyrite oxidation to the redox transformations that occur in response to the injection of oxygenated water.

Stochastic analysis of the efficiency of coupled hydraulic-physical barriers to contain solute plumes in highly heterogeneous aquifers

Science.gov (United States)

Pedretti, Daniele; Masetti, Marco; Beretta, Giovanni Pietro

2017-10-01

The expected long-term efficiency of vertical cutoff walls coupled to pump-and-treat technologies to contain solute plumes in highly heterogeneous aquifers was analyzed. A well-characterized case study in Italy, with a hydrogeological database of 471 results from hydraulic tests performed on the aquifer and the surrounding 2-km-long cement-bentonite (CB) walls, was used to build a conceptual model and assess a representative remediation site adopting coupled technologies. In the studied area, the aquifer hydraulic conductivity Ka [m/d] is log-normally distributed with mean E (Ya) = 0.32 , variance σYa2 = 6.36 (Ya = lnKa) and spatial correlation well described by an exponential isotropic variogram with integral scale less than 1/12 the domain size. The hardened CB wall's hydraulic conductivity, Kw [m/d], displayed strong scaling effects and a lognormal distribution with mean E (Yw) = - 3.43 and σYw2 = 0.53 (Yw =log10Kw). No spatial correlation of Kw was detected. Using this information, conservative transport was simulated across a CB wall in spatially correlated 1-D random Ya fields within a numerical Monte Carlo framework. Multiple scenarios representing different Kw values were tested. A continuous solute source with known concentration and deterministic drains' discharge rates were assumed. The efficiency of the confining system was measured by the probability of exceedance of concentration over a threshold (C∗) at a control section 10 years after the initial solute release. It was found that the stronger the aquifer heterogeneity, the higher the expected efficiency of the confinement system and the lower the likelihood of aquifer pollution. This behavior can be explained because, for the analyzed aquifer conditions, a lower Ka generates more pronounced drawdown in the water table in the proximity of the drain and consequently a higher advective flux towards the confined area, which counteracts diffusive fluxes across the walls. Thus, a higher σYa2 results

Geochemical Impacts of Leaking CO2 from Subsurface Storage Reservoirs to Unconfined and Confined Aquifers

Energy Technology Data Exchange (ETDEWEB)

Qafoku, Nikolla; Brown, Christopher F.; Wang, Guohui; Sullivan, E. C.; Lawter, Amanda R.; Harvey, Omar R.; Bowden, Mark

2013-04-15

Experimental research work has been conducted and is undergoing at Pacific Northwest National Laboratory (PNNL) to address a variety of scientific issues related with the potential leaks of the carbon dioxide (CO2) gas from deep storage reservoirs. The main objectives of this work are as follows: • Develop a systematic understanding of how CO2 leakage is likely to influence pertinent geochemical processes (e.g., dissolution/precipitation, sorption/desorption and redox reactions) in the aquifer sediments. • Identify prevailing environmental conditions that would dictate one geochemical outcome over another. • Gather useful information to support site selection, risk assessment, policy-making, and public education efforts associated with geological carbon sequestration. In this report, we present results from experiments conducted at PNNL to address research issues related to the main objectives of this effort. A series of batch and column experiments and solid phase characterization studies (quantitative x-ray diffraction and wet chemical extractions with a concentrated acid) were conducted with representative rocks and sediments from an unconfined, oxidizing carbonate aquifer, i.e., Edwards aquifer in Texas, and a confined aquifer, i.e., the High Plains aquifer in Kansas. These materials were exposed to a CO2 gas stream simulating CO2 gas leaking scenarios, and changes in aqueous phase pH and chemical composition were measured in liquid and effluent samples collected at pre-determined experimental times. Additional research to be conducted during the current fiscal year will further validate these results and will address other important remaining issues. Results from these experimental efforts will provide valuable insights for the development of site-specific, generation III reduced order models. In addition, results will initially serve as input parameters during model calibration runs and, ultimately, will be used to test model predictive capability and

Impact of sub-horizontal discontinuities and vertical heterogeneities on recharge processes in a weathered crystalline aquifer in southern India

Science.gov (United States)

Nicolas, Madeleine; Selles, Adrien; Bour, Olivier; Maréchal, Jean-Christophe; Crenner, Marion; Wajiduddin, Mohammed; Ahmed, Shakeel

2017-04-01

In the face of increasing demands for irrigated agriculture, many states in India are facing water scarcity issues, leading to severe groundwater depletion. Because perennial water resources in southern India consist mainly of crystalline aquifers, understanding how recharge takes place and the role of preferential flow zones in such heterogeneous media is of prime importance for successful and sustainable aquifer management. Here we investigate how vertical heterogeneities and highly transmissive sub-horizontal discontinuities may control groundwater flows and recharge dynamics. Recharge processes in the vadose zone were examined by analysing the propagation of an infiltration front and mass transfers resulting from the implementation of a managed aquifer recharge (MAR) structure. Said structure was set up in the Experimental Hydrogeological Park in Telangana (Southern India), a well-equipped and continuously monitored site, which is periodically supplied with surface water deviated from the nearby Musi river, downstream of Hyderabad. An initial volume balance equation was applied to quantify the overall inputs from the MAR structure into the groundwater system, which was confirmed using a chloride mass balance approach. To understand how this incoming mass is then distributed within the aquifer, we monitored the evolution of water volumes in the tank, and the resulting lateral propagation front observed in the surrounding borehole network. Borehole logs of temperature and conductivity were regularly performed to identify preferential flow paths. As a result we observed that mass transfers take place in the way of preferential lateral flow through the most transmissive zones of the profile. These include the interface between the lower portion of the upper weathered horizon (the saprolite) and the upper part of the underlying fissured granite, as well as the first flowing fractures. This leads to a rapid lateral transfer of recharge, which allows quick

Improved Efficiency of Miscible CO2 Floods and Enhanced Prospects for CO2 Flooding Heterogeneous Reservoirs; ANNUAL

International Nuclear Information System (INIS)

Grigg, Reid B.; Schechter, David S.

1999-01-01

The goal of this project is to improve the efficiency of miscible CO2 floods and enhance the prospects for flooding heterogeneous reservoirs. This report provides results of the second year of the three-year project that will be exploring three principles: (1) Fluid and matrix interactions (understanding the problems). (2) Conformance control/sweep efficiency (solving the problems. 3) Reservoir simulation for improved oil recovery (predicting results)

Water Influx, and Its Effect on Oil Recovery: Part 1. Aquifer Flow, SUPRI TR-103

Energy Technology Data Exchange (ETDEWEB)

Brigham, William E.

1999-08-09

Natural water encroachment is commonly seen in many oil and gas reservoirs. In fact, overall, there is more water than oil produced from oil reservoirs worldwide. Thus it is clear that an understanding of reservoir/aquifer interaction can be an important aspect of reservoir management to optimize recovery of hydrocarbons. Although the mathematics of these processes are difficult, they are often amenable to analytical solution and diagnosis. Thus this will be the ultimate goal of a series of reports on this subject. This first report deals only with aquifer behavior, so it does not address these important reservoir/aquifer issues. However, it is an important prelude to them, for the insight gained gives important clues on how to address reservoir/aquifer problems. In general when looking at aquifer flow, there are two convenient inner boundary conditions that can be considered; constant pressure or constant flow rate. There are three outer boundary conditions that are convenient to consider; infinite, closed and constant pressure. And there are three geometries that can be solved reasonably easily; linear, radial and spherical. Thus there are a total of eighteen different solutions that can be analyzed.

Scale-up of miscible flood processes for heterogeneous reservoirs. Final report

Energy Technology Data Exchange (ETDEWEB)

Orr, F.M. Jr.

1996-04-01

Results of a wide-ranging investigation of the scaling of gas injection processes are reported. The research examines how the physical mechanisms at work during a gas injection project interact to determine process performance. In particular, the authors examine: the interactions of equilibrium phase behavior and two-phase flow that determine local displacement efficiency and minimum miscibility pressure, the combined effects of viscous fingering, gravity segregation and heterogeneity that control sweep efficiency in 2- and 3-dimensional porous media, the use of streamtube/streamline methods to create very efficient simulation technique for multiphase compositional displacements, the scaling of viscous, capillary and gravity forces for heterogeneous reservoirs, and the effects of the thin films and spreading behavior on three-phase flow. The following key results are documented: rigorous procedures for determination of minimum miscibility pressure (MMP) or minimum miscibility enrichment (MME) for miscibility have been developed for multicomponent systems; the complex dependence of MMP`s for nitrogen/methane floods on oil and injection gas composition observed experimentally is explained for the first time; the presence of layer-like heterogeneities strongly influences the interplay of gravity segregation and viscous fingering, as viscous fingers adapt to preferential flow paths and low permeability layers restrict vertical flow; streamtube/streamline simulation techniques are demonstrated for a variety of injection processes in 2 and 3 dimensions; quantitative scaling estimates for the transitions from capillary-dominated to gravity-dominated to viscous-dominated flows are reported; experimental results are given that demonstrate that high pressure CO{sub 2} can be used to generate low IFT gravity drainage in fractured reservoirs if fractures are suitably connected; and the effect of wetting and spreading behavior on three-phase flow is described. 209 refs.

Simulation of the mulltizones clastic reservoir: A case study of Upper Qishn Clastic Member, Masila Basin-Yemen

Science.gov (United States)

Khamis, Mohamed; Marta, Ebrahim Bin; Al Natifi, Ali; Fattah, Khaled Abdel; Lashin, Aref

2017-06-01

The Upper Qishn Clastic Member is one of the main oil-bearing reservoirs that are located at Masila Basin-Yemen. It produces oil from many zones with different reservoir properties. The aim of this study is to simulate and model the Qishn sandstone reservoir to provide more understanding of its properties. The available, core plugs, petrophysical, PVT, pressure and production datasets, as well as the seismic structural and geologic information, are all integrated and used in the simulation process. Eclipse simulator was used as a powerful tool for reservoir modeling. A simplified approach based on a pseudo steady-state productivity index and a material balance relationship between the aquifer pressure and the cumulative influx, is applied. The petrophysical properties of the Qishn sandstone reservoir are mainly investigated based on the well logging and core plug analyses. Three reservoir zones of good hydrocarbon potentiality are indicated and named from above to below as S1A, S1C and S2. Among of these zones, the S1A zone attains the best petrophysical and reservoir quality properties. It has an average hydrocarbon saturation of more than 65%, high effective porosity up to 20% and good permeability record (66 mD). The reservoir structure is represented by faulted anticline at the middle of the study with a down going decrease in geometry from S1A zone to S2 zone. It is limited by NE-SW and E-W bounding faults, with a weak aquifer connection from the east. The analysis of pressure and PVT data has revealed that the reservoir fluid type is dead oil with very low gas liquid ratio (GLR). The simulation results indicate heterogeneous reservoir associated with weak aquifer, supported by high initial water saturation and high water cut. Initial oil in place is estimated to be around 628 MM BBL, however, the oil recovery during the period of production is very low (<10%) because of the high water cut due to the fractures associated with many faults. Hence, secondary and

Method of improving heterogeneous oil reservoir polymer flooding effect by positively-charged gel profile control

Science.gov (United States)

Zhao, Ling; Xia, Huifen

2018-01-01

The project of polymer flooding has achieved great success in Daqing oilfield, and the main oil reservoir recovery can be improved by more than 15%. But, for some strong oil reservoir heterogeneity carrying out polymer flooding, polymer solution will be inefficient and invalid loop problem in the high permeability layer, then cause the larger polymer volume, and a significant reduction in the polymer flooding efficiency. Aiming at this problem, it is studied the method that improves heterogeneous oil reservoir polymer flooding effect by positively-charged gel profile control. The research results show that the polymer physical and chemical reaction of positively-charged gel with the residual polymer in high permeability layer can generate three-dimensional network of polymer, plugging high permeable layer, and increase injection pressure gradient, then improve the effect of polymer flooding development. Under the condition of the same dosage, positively-charged gel profile control can improve the polymer flooding recovery factor by 2.3∼3.8 percentage points. Under the condition of the same polymer flooding recovery factor increase value, after positively-charged gel profile control, it can reduce the polymer volume by 50 %. Applying mechanism of positively-charged gel profile control technology is feasible, cost savings, simple construction, and no environmental pollution, therefore has good application prospect.

Megaporosity and permeability of Thalassinoides-dominated ichnofabrics in the Cretaceous karst-carbonate Edwards-Trinity aquifer system, Texas

Science.gov (United States)

Cunningham, Kevin J.; Sukop, Michael C.

2012-01-01

Current research has demonstrated that trace fossils and their related ichnofabrics can have a critical impact on the fluid-flow properties of hydrocarbon reservoirs and groundwater aquifers. Most petroleum-associated research has used ichnofabrics to support the definition of depositional environments and reservoir quality, and has concentrated on siliciclastic reservoir characterization and, to a lesser degree, carbonate reservoir characterization (for example, Gerard and Bromley, 2008; Knaust, 2009). The use of ichnology in aquifer characterization has almost entirely been overlooked by the hydrologic community because the dynamic reservoir-characterization approach has not caught on with hydrologists and so hydrology is lagging behind reservoir engineering in this area (de Marsily and others, 2005). The objective of this research is to show that (1) ichnofabric analysis can offer a productive methodology for purposes of carbonate aquifer characterization, and (2) a clear relation can exist between ichnofabrics and groundwater flow in carbonate aquifers.

Implications of heterogeneous fracture distribution on reservoir quality; an analogue from the Torridon Group sandstone, Moine Thrust Belt, NW Scotland

Science.gov (United States)

Watkins, Hannah; Healy, David; Bond, Clare E.; Butler, Robert W. H.

2018-03-01

Understanding fracture network variation is fundamental in characterising fractured reservoirs. Simple relationships between fractures, stress and strain are commonly assumed in fold-thrust structures, inferring relatively homogeneous fracture patterns. In reality fractures are more complex, commonly appearing as heterogeneous networks at outcrop. We use the Achnashellach Culmination (NW Scotland) as an outcrop analogue to a folded tight sandstone reservoir in a thrust belt. We present fracture data is collected from four fold-thrust structures to determine how fracture connectivity, orientation, permeability anisotropy and fill vary at different structural positions. We use a 3D model of the field area, constructed using field observations and bedding data, and geomechanically restored using Move software, to determine how factors such as fold curvature and strain influence fracture variation. Fracture patterns in the Torridon Group are consistent and predictable in high strain forelimbs, however in low strain backlimbs fracture patterns are inconsistent. Heterogeneities in fracture connectivity and orientation in low strain regions do not correspond to fluctuations in strain or fold curvature. We infer that where strain is low, other factors such as lithology have a greater control on fracture formation. Despite unpredictable fracture attributes in low strain regions, fractured reservoir quality would be highest here because fractures in high strain forelimbs are infilled with quartz. Heterogeneities in fracture attribute data on fold backlimbs mean that fractured reservoir quality and reservoir potential is difficult to predict.

An Aquifer Thermal Energy Storage (ATES) System for Continuous and Sustainable Cold Supply in Oman

Science.gov (United States)

Winterleitner, G.; Schütz, F.; Huenges, E.

2016-12-01

The aim of the GeoSolCool research programme between the German Research Centre for Geoscience (GFZ) and The Research Council of Oman (TRC) is the development of an innovative and sustainable cooling system in combination with an aquifer thermal energy storage system in northern Oman. An integral part of this project is the design of a subsurface aquifer reservoir system for storage of thermal energy through hot water injection. An accurate characterisation of potential storage horizons is thus essential to ensure optimal efficiency of the cooling system. The study area, 40 km west of Muscat is characterised by a thick Cenozoic mixed carbonate-siliciclastic sedimentary succession, containing at least 3 aquifer horizons. We used a multidisciplinary approach for the initial ATES development phase, including geological fieldwork dovetailed with remote sensing analyses, thin-section analyses, geological modelling and reservoir fluid flow forecasting. First results indicate two potential storage horizons: (1) a Miocene-aged clastic-dominated alluvial fan system and (2) an Eocene carbonate sequence. The alluvial fan system is a more than 300 m thick, coarse clastic (mainly gravels and sandstones) succession of coalesced individual fans. Thin-section analyses showed that hydraulic parameters are favourable for the gravel and sandstone intervals but reservoir architecture is complex due to multiple generations of interconnecting fans with highly heterogeneous facies distributions. The Eocene carbonates were deposited in a carbonate ramp setting, strongly influenced by currents and storm events. Individual facies belts extend over kilometres and thus horizontal reservoir connectivity is expected to be good with minor facies variability. Thin-section analyses showed that especially the fossil-rich sections show good storage qualities. Fluid flow forecasting indicate that both potential horizons have good to very good storage characteristics. However, intense diagenetic

Variations in hydraulic conductivity with scale of measurement during aquifer tests in heterogeneous, porous carbonate rocks

Science.gov (United States)

Schulze-Makuch, Dirk; Cherkauer, Douglas S.

Previous studies have shown that hydraulic conductivity of an aquifer seems to increase as the portion of the aquifer tested increases. To date, such studies have all relied on different methods to determine hydraulic conductivity at each scale of interest, which raises the possibility that the observed increase in hydraulic conductivity is due to the measurement method, not to the scale. This study analyzes hydraulic conductivity with respect to scale during individual aquifer tests in porous, heterogeneous carbonate rocks in southeastern Wisconsin, USA. Results from this study indicate that hydraulic conductivity generally increases during an individual test as the volume of aquifer impacted increases, and the rate of this increase is the same as the rate of increase determined by using different measurement methods. Thus, scale dependence of hydraulic conductivity during single tests does not depend on the method of measurement. This conclusion is supported by 22 of 26 aquifer tests conducted in porous-flow-dominated carbonate units within the aquifer. Instead, scale dependency is probably caused by heterogeneities within the aquifer, a conclusion supported by digital simulation. All of the observed types of hydraulic-conductivity variations with scale during individual aquifer tests can be explained by a conceptual model of a simple heterogeneous aquifer composed of high-conductivity zones within a low-conductivity matrix. Résumé Certaines études ont montré que la conductivité hydraulique d'un aquifère semble augmenter en même temps que la partie testée de l'aquifère s'étend. Jusqu'à présent, ces études ont toutes reposé sur des méthodes de détermination de la conductivité hydraulique différentes pour chaque niveau d'échelle, ce qui a conduit à penser que l'augmentation observée de la conductivité hydraulique pouvait être due aux méthodes de mesure et non à l'effet d'échelle. Cette étude analyse la conductivité hydraulique par

Transport of reservoir fines

DEFF Research Database (Denmark)

Yuan, Hao; Shapiro, Alexander; Stenby, Erling Halfdan

Modeling transport of reservoir fines is of great importance for evaluating the damage of production wells and infectivity decline. The conventional methodology accounts for neither the formation heterogeneity around the wells nor the reservoir fines’ heterogeneity. We have developed an integral...... dispersion equation in modeling the transport and the deposition of reservoir fines. It successfully predicts the unsymmetrical concentration profiles and the hyperexponential deposition in experiments....

Submarine fan reservoir architecture and heterogeneity influence on hard-to-recover reserves. Achimov Fm

International Nuclear Information System (INIS)

Kondratyev, A; Rukavishnikov, V; Maksyutin, K; Shakirzyanov, L

2015-01-01

Due to the fact that simulation model calculation is the basic method used for estimating the efficiency of a development strategy, it is necessary to design geological and simulation models within which reservoir properties and heterogeneity are defined. In addition, the estimation of the influence of various kinds of geological uncertainties on reservoir properties will allow defining a more effective development strategy. The Achimov formation of the Vingapur oil field was considered in the current study. The northern part of the field is now quite attractive for the development of this formation. The goal of this paper was the complex investigation of petrophysical properties to make a prognosis for the field and assess the effect of geologic uncertainties on production. The first step implied studying the western part of the field where core data are available, the next stage was developing an algorithm to make a prognosis for properties and the geologic and reservoir simulation models were eventually constructed to study the effect of geologic uncertainties in the northern part. As the result of the sedimentary analysis, a model of deposition was defined within which structural elements were also determined. On the basis of wireline and core data analysis, the petrophysical model of the reservoir was build where the method of Rock Types identification using specific cut-off values for wireline logs was applied for the evaluations. In addition to this, the Hydraulic Flow unit approach was employed, which allowed estimating the less extensively explored areas of the field where core had not been retrieved from. Also, this paper provides the results of the seismic attribute analysis and calculations in order to characterize uncertainty in cumulative oil production under the influence of petrophysical and geological heterogeneity

Application of multiple-point geostatistics to simulate the effect of small scale aquifer heterogeneity on the efficiency of Aquifer Thermal Energy Storage (ATES)

Science.gov (United States)

Possemiers, Mathias; Huysmans, Marijke; Batelaan, Okke

2015-04-01

Adequate aquifer characterization and simulation using heat transport models are indispensible for determining the optimal design for Aquifer Thermal Energy Storage (ATES) systems and wells. Recent model studies indicate that meter scale heterogeneities in the hydraulic conductivity field introduce a considerable uncertainty in the distribution of thermal energy around an ATES system and can lead to a reduction in the thermal recoverability. In this paper, the influence of centimeter scale clay drapes on the efficiency of a doublet ATES system and the distribution of the thermal energy around the ATES wells are quantified. Multiple-point geostatistical simulation of edge properties is used to incorporate the clay drapes in the models. The results show that clay drapes have an influence both on the distribution of thermal energy in the subsurface and on the efficiency of the ATES system. The distribution of the thermal energy is determined by the strike of the clay drapes, with the major axis of anisotropy parallel to the clay drape strike. The clay drapes have a negative impact (3.3 - 3.6%) on the energy output in the models without a hydraulic gradient. In the models with a hydraulic gradient, however, the presence of clay drapes has a positive influence (1.6 - 10.2%) on the energy output of the ATES system. It is concluded that it is important to incorporate small scale heterogeneities in heat transport models to get a better estimate on ATES efficiency and distribution of thermal energy.

Blocking effect and numerical study of polymer particles dispersion flooding in heterogeneous reservoir

Science.gov (United States)

Zhu, Weiyao; Li, Jianhui; Lou, Yu

2018-02-01

Polymer flooding has become an effective way to improve the sweep efficiency in many oil fields. Many scholars have carried out a lot of researches on the mechanism of polymer flooding. In this paper, the effect of polymer on seepage is analyzed. The blocking effect of polymer particles was studied experimentally, and the residual resistance coefficient (RRF) were used to represent the blocking effect. We also build a mathematical model for heterogeneous concentration distribution of polymer particles. Furthermore, the effects of polymer particles on reservoir permeability, fluid viscosity and relative permeability are considered, and a two-phase flow model of oil and polymer particles is established. In addition, the model was tested in the heterogeneous stratum model, and three influencing factors, such as particle concentration, injection volume and PPD (short for polymer particle dispersion) injection time, were analyzed. Simulation results show that PPD can effectively improve sweep efficiency and especially improve oil recovery of low permeability layer. Oil recovery increases with the increase of particle concentration, but oil recovery increase rate gradually decreases with that. The greater the injected amount of PPD, the greater oil recovery and the smaller oil recovery increase rate. And there is an optimal timing to inject PPD for specific reservoir.

Application of multiple-point geostatistics to simulate the effect of small-scale aquifer heterogeneity on the efficiency of aquifer thermal energy storage

Science.gov (United States)

Possemiers, Mathias; Huysmans, Marijke; Batelaan, Okke

2015-08-01

Adequate aquifer characterization and simulation using heat transport models are indispensible for determining the optimal design for aquifer thermal energy storage (ATES) systems and wells. Recent model studies indicate that meter-scale heterogeneities in the hydraulic conductivity field introduce a considerable uncertainty in the distribution of thermal energy around an ATES system and can lead to a reduction in the thermal recoverability. In a study site in Bierbeek, Belgium, the influence of centimeter-scale clay drapes on the efficiency of a doublet ATES system and the distribution of the thermal energy around the ATES wells are quantified. Multiple-point geostatistical simulation of edge properties is used to incorporate the clay drapes in the models. The results show that clay drapes have an influence both on the distribution of thermal energy in the subsurface and on the efficiency of the ATES system. The distribution of the thermal energy is determined by the strike of the clay drapes, with the major axis of anisotropy parallel to the clay drape strike. The clay drapes have a negative impact (3.3-3.6 %) on the energy output in the models without a hydraulic gradient. In the models with a hydraulic gradient, however, the presence of clay drapes has a positive influence (1.6-10.2 %) on the energy output of the ATES system. It is concluded that it is important to incorporate small-scale heterogeneities in heat transport models to get a better estimate on ATES efficiency and distribution of thermal energy.

Field study of macrodispersion in a heterogeneous aquifer. 2

International Nuclear Information System (INIS)

Boggs, J.M.; Rehfeldt, K.R.

1990-01-01

Observations of the spatial variability of the hydraulic conductivity field at the site of a large-scale natural gradient tracer experiment located at Columbus Air Force Base in Mississippi are presented. Direct measurements of hydraulic conductivity of the heterogeneous alluvial aquifer at the site were made using a variety of methods including aquifer tests, borehole flowmeter logging, double-packer tests, slug tests, and a newly developed laboratory permeameter to test undisturbed soil cores. The borehole flowmeter method was shown to be the most effective method for measuring conductivity variability. Estimates of the log hydraulic conductivity variance (σ 2 lnL ) and the horizontal and vertical correlation sales, (λ h and λ v ) of 4.5, 12 m, and 1.5 m, respectively, were calculated assuming second order stationarity of the conductivity field. Large-scale spatial variations in the mean groundwater velocity indicated by the natural gradient tracer experiment, which were shown to be a direct result of contrasts in the mean hydraulic conductivity along the plume pathway, strongly suggested the presence of a conductivity trend. The measured hydraulic conductivity data were subsequently detrended using least-squares regression to remove three-dimensional polynomials. The third-order polynomial was judged the best representation of the conductivity drift based on its overall compatibility with the groundwater flow field inferred from the tracer plume observations. Significantly lower estimates for σ 2 lnK , λ h , and λ v of 2.8, 5.3 m, and 0.7 m, respectively, were obtained from the third-order log conductivity residuals. The experience with the borehole flowmeter technique shows the feasibility of observing the statistical parameters of the hydraulic conductivity variability required for stochastic models of macrodispersion. (Author) (20 refs., 3 figs., 10 tabs.)

Sedimentological analysis of a contaminated groundwater aquifer

International Nuclear Information System (INIS)

Towse, D.

1991-01-01

The use of sedimentological reservoir analysis techniques adapted from standard oilfield practice can improve the efficiency and reduce the costs of the evaluation of groundwater aquifers and the design of restoration programs. An evaluation/restoration program at a site in California drilled over 200 test wells in about 750 ac. All wells were logged lithologically and with wireline. The shallow aquifer is a complex braided alluvial floodplain deposit of Late Quaternary age. Analysis demonstrates depositional and erosional responses to periodic hinterland uplifts and to changing climatic conditions. Channel, overbank, lacustrine, and minor deltaic deposits can be recognized. The aquifer architecture has been interpreted to explain the movement of fuel and halogenated hydrocarbon solvents in the sediments and water. Routine engineering geology techniques and hydrologic tests were used to evaluate contamination and to design experimental restoration processes. As demonstrated here, sedimentological techniques show promise in reducing the costs and time required for this type of study. The abundant detailed data will be used in an attempt to develop a microcomputer-based expert system for rapid preliminary analyses of similar aquifers or reservoirs

Integrated reservoir characterization: Improvement in heterogeneities stochastic modelling by integration of additional external constraints

Energy Technology Data Exchange (ETDEWEB)

Doligez, B.; Eschard, R. [Institut Francais du Petrole, Rueil Malmaison (France); Geffroy, F. [Centre de Geostatistique, Fontainebleau (France)] [and others

1997-08-01

The classical approach to construct reservoir models is to start with a fine scale geological model which is informed with petrophysical properties. Then scaling-up techniques allow to obtain a reservoir model which is compatible with the fluid flow simulators. Geostatistical modelling techniques are widely used to build the geological models before scaling-up. These methods provide equiprobable images of the area under investigation, which honor the well data, and which variability is the same than the variability computed from the data. At an appraisal phase, when few data are available, or when the wells are insufficient to describe all the heterogeneities and the behavior of the field, additional constraints are needed to obtain a more realistic geological model. For example, seismic data or stratigraphic models can provide average reservoir information with an excellent areal coverage, but with a poor vertical resolution. New advances in modelisation techniques allow now to integrate this type of additional external information in order to constrain the simulations. In particular, 2D or 3D seismic derived information grids, or sand-shale ratios maps coming from stratigraphic models can be used as external drifts to compute the geological image of the reservoir at the fine scale. Examples are presented to illustrate the use of these new tools, their impact on the final reservoir model, and their sensitivity to some key parameters.

Estimating Groundwater Mounding in Sloping Aquifers for Managed Aquifer Recharge.

Science.gov (United States)

Zlotnik, Vitaly A; Kacimov, Anvar; Al-Maktoumi, Ali

2017-11-01

Design of managed aquifer recharge (MAR) for augmentation of groundwater resources often lacks detailed data, and simple diagnostic tools for evaluation of the water table in a broad range of parameters are needed. In many large-scale MAR projects, the effect of a regional aquifer base dip cannot be ignored due to the scale of recharge sources (e.g., wadis, streams, reservoirs). However, Hantush's (1967) solution for a horizontal aquifer base is commonly used. To address sloping aquifers, a new closed-form analytical solution for water table mound accounts for the geometry and orientation of recharge sources at the land surface with respect to the aquifer base dip. The solution, based on the Dupiuit-Forchheimer approximation, Green's function method, and coordinate transformations is convenient for computing. This solution reveals important MAR traits in variance with Hantush's solution: mounding is limited in time and space; elevation of the mound is strongly affected by the dip angle; and the peak of the mound moves over time. These findings have important practical implications for assessment of various MAR scenarios, including waterlogging potential and determining proper rates of recharge. Computations are illustrated for several characteristic MAR settings. © 2017, National Ground Water Association.

Heterogeneous carbonaceous matter in sedimentary rock lithocomponents causes significant trichloroethylene (TCE) sorption in a low organic carbon content aquifer/aquitard system.

Science.gov (United States)

Choung, Sungwook; Zimmerman, Lisa R; Allen-King, Richelle M; Ligouis, Bertrand; Feenstra, Stanley

2014-10-15

This study evaluated the effects of heterogeneous thermally altered carbonaceous matter (CM) on trichloroethylene (TCE) sorption for a low fraction organic carbon content (foc) alluvial sedimentary aquifer and aquitard system (foc=0.046-0.105%). The equilibrium TCE sorption isotherms were highly nonlinear with Freundlich exponents of 0.46-0.58. Kerogen+black carbon was the dominant CM fraction extracted from the sediments and accounted for >60% and 99% of the total in the sands and silt, respectively. Organic petrological examination determined that the kerogen included abundant amorphous organic matter (bituminite), likely of marine origin. The dark calcareous siltstone exhibited the greatest TCE sorption among aquifer lithocomponents and accounted for most sorption in the aquifer. The results suggest that the source of the thermally altered CM, which causes nonlinear sorption, was derived from parent Paleozoic marine carbonate rocks that outcrop throughout much of New York State. A synthetic aquifer-aquitard unit system (10% aquitard) was used to illustrate the effect of the observed nonlinear sorption on mass storage potential at equilibrium. The calculation showed that >80% of TCE mass contained in the aquifer was sorbed on the aquifer sediment at aqueous concentration TCE groundwater plume in the aquifer studied. It is implied that sorption may similarly contribute to TCE persistence in other glacial alluvial aquifers with similar geologic characteristics, i.e., comprised of sedimentary rock lithocomponents that contain thermally altered CM. Copyright © 2014 Elsevier B.V. All rights reserved.

The fate of pesticides in soil and aquifers from a small-scale point of view: Does microbial and spatial heterogeneity have an impact?

DEFF Research Database (Denmark)

Aamand, J.; Badawi, N.; Rosenbom, Annette Elisabeth

Millions of tonnes of pesticides are used each year worldwide in agricultural production resulting in pollution of groundwater aquifers. There is, however, a striking contrast between the input levels (up to several kg per hectare) and the contaminant concentrations detected in groundwater, which...... are normally in the microgram to nanogram per litre range. Resent research has revealed a large spatial variation in pesticide mineralisation potentials, but little is known about how these variations/heterogeneities affect the fate of contaminants. We analysed how mineralisation potentials of phenoxy acid...... herbicides (MCPA, 2,4-D) were spatially distributed in soil, subsoil, and groundwater aquifers using a 96-well microplate mineralisation assay. In the top soil, all samples showed rapid mineralisation following Monod mineralisation kinetics. In the subsoil sediments, a more heterogeneous distribution...

Heterogeneity-enhanced gas phase formation in shallow aquifers during leakage of CO2-saturated water from geologic sequestration sites

DEFF Research Database (Denmark)

Plampin, Michael R.; Lassen, Rune Nørbæk; Sakaki, Toshihiro

2014-01-01

sands. Soil moisture sensors were utilized to observe the formation of gas phase near the porous media interfaces. Results indicate that the conditions under which heterogeneity controls gas phase evolution can be successfully predicted through analysis of simple parameters, including the dissolved CO2......, it is important to understand the physical processes that CO2 will undergo as it moves through naturally heterogeneous porous media formations. Previous studies have shown that heterogeneity can enhance the evolution of gas phase CO2 in some cases, but the conditions under which this occurs have not yet been...... quantitatively defined, nor tested through laboratory experiments. This study quantitatively investigates the effects of geologic heterogeneity on the process of gas phase CO2 evolution in shallow aquifers through an extensive set of experiments conducted in a column that was packed with layers of various test...

Simulation of CO2 Sequestration at Rock Spring Uplift, Wyoming: Heterogeneity and Uncertainties in Storage Capacity, Injectivity and Leakage

Energy Technology Data Exchange (ETDEWEB)

Deng, Hailin [Los Alamos National Laboratory; Dai, Zhenxue [Los Alamos National Laboratory; Jiao, Zunsheng [Wyoming State Geological Survey; Stauffer, Philip H. [Los Alamos National Laboratory; Surdam, Ronald C. [Wyoming State Geological Survey

2011-01-01

Many geological, geochemical, geomechanical and hydrogeological factors control CO{sub 2} storage in subsurface. Among them heterogeneity in saline aquifer can seriously influence design of injection wells, CO{sub 2} injection rate, CO{sub 2} plume migration, storage capacity, and potential leakage and risk assessment. This study applies indicator geostatistics, transition probability and Markov chain model at the Rock Springs Uplift, Wyoming generating facies-based heterogeneous fields for porosity and permeability in target saline aquifer (Pennsylvanian Weber sandstone) and surrounding rocks (Phosphoria, Madison and cap-rock Chugwater). A multiphase flow simulator FEHM is then used to model injection of CO{sub 2} into the target saline aquifer involving field-scale heterogeneity. The results reveal that (1) CO{sub 2} injection rates in different injection wells significantly change with local permeability distributions; (2) brine production rates in different pumping wells are also significantly impacted by the spatial heterogeneity in permeability; (3) liquid pressure evolution during and after CO{sub 2} injection in saline aquifer varies greatly for different realizations of random permeability fields, and this has potential important effects on hydraulic fracturing of the reservoir rock, reactivation of pre-existing faults and the integrity of the cap-rock; (4) CO{sub 2} storage capacity estimate for Rock Springs Uplift is 6614 {+-} 256 Mt at 95% confidence interval, which is about 36% of previous estimate based on homogeneous and isotropic storage formation; (5) density profiles show that the density of injected CO{sub 2} below 3 km is close to that of the ambient brine with given geothermal gradient and brine concentration, which indicates CO{sub 2} plume can sink to the deep before reaching thermal equilibrium with brine. Finally, we present uncertainty analysis of CO{sub 2} leakage into overlying formations due to heterogeneity in both the target saline

Spatial heterogeneity and seasonal succession of phytoplankton along the longitudinal gradient in a eutrophic reservoir

Czech Academy of Sciences Publication Activity Database

Rychtecký, Pavel; Znachor, Petr

2011-01-01

Roč. 663, č. 1 (2011), s. 175-186 ISSN 0018-8158 R&D Projects: GA ČR(CZ) GP206/07/P407; GA ČR(CZ) GA206/08/0015 Institutional research plan: CEZ:AV0Z60170517 Keywords : phytoplankton * reservoir * spatial heterogeneity * seasonal succession * functional classification * f lood event Subject RIV: DA - Hydrology ; Limnology Impact factor: 1.784, year: 2011

Apparent directional mass-transfer capacity coefficients in three-dimensional anisotropic heterogeneous aquifers under radial convergent transport

Science.gov (United States)

Pedretti, D.; Fernàndez-Garcia, D.; Sanchez-Vila, X.; Bolster, D.; Benson, D. A.

2014-02-01

Aquifer hydraulic properties such as hydraulic conductivity (K) are ubiquitously heterogeneous and typically only a statistical characterization can be sought. Additionally, statistical anisotropy at typical characterization scales is the rule. Thus, regardless of the processes governing solute transport at the local (pore) scale, transport becomes non-Fickian. Mass-transfer models provide an efficient tool that reproduces observed anomalous transport; in some cases though, these models lack predictability as model parameters cannot readily be connected to the physical properties of aquifers. In this study, we focus on a multirate mass-transfer model (MRMT), and in particular the apparent capacity coefficient (β), which is a strong indicator of the potential of immobile zones to capture moving solute. We aim to find if the choice of an apparent β can be phenomenologically related to measures of statistical anisotropy. We analyzed an ensemble of random simulations of three-dimensional log-transformed multi-Gaussian permeability fields with stationary anisotropic correlation under convergent flow conditions. It was found that apparent β also displays an anisotropic behavior, physically controlled by the aquifer directional connectivity, which in turn is controlled by the anisotropic correlation model. A high hydraulic connectivity results in large β values. These results provide new insights into the practical use of mass-transfer models for predictive purposes.

Characterizing Structural and Stratigraphic Heterogeneities in a Faulted Aquifer Using Pump Tests with an Array of Westbay Multilevel Monitoring Wells

Science.gov (United States)

Johnson, B.; Zhurina, E. N.

2001-12-01

We are developing and assessing field testing and analysis methodologies for quantitative characterization of aquifer heterogenities using data measured in an array of multilevel monitoring wells (MLW) during pumping and recovery well tests. We have developed a unique field laboratory to determine the permeability field in a 20m by 40m by 70m volume in the fault partitioned, siliciclastic Hickory aquifer system in central Texas. The site incorporates both stratigraphic variations and a normal fault system that partially offsets the aquifer and impedes cross-fault flow. We constructed a high-resolution geologic model of the site based upon 1050 m of core and a suite of geophysical logs from eleven, closely spaced (3-10m), continuously cored boreholes to depths of 125 m. Westbay multilevel monitoring systems installed in eight holes provide 94 hydraulically isolated measurement zones and 25 injection zones. A good geologic model is critical to proper installation of the MLW. Packers are positioned at all significant fault piercements and selected, laterally extensive, clay-rich strata. Packers in adjacent MLW bracket selected hydrostratigraphic intervals. Pump tests utilized two, uncased, fully penetrating irrigation wells that straddle the fault system and are in close proximity (7 to 65 m) to the MLW. Pumping and recovery transient pressure histories were measured in 85 zones using pressure transducers with a resolution of 55 Pa (0.008 psi). The hydraulic response is that of an anisotropic, unconfined aquifer. The transient pressure histories vary significantly from zone to zone in a single MLW as well as between adjacent MLW. Derivative plots are especially useful for differentiating details of pressure histories. Based on the geologic model, the derivative curve of a zone reflects its absolute vertical position, vertical stratigraphic position, and proximity to either a fault or significant stratigraphic heterogeneity. Additional forward modeling is needed to

Possibility of predicting the water drive mechanism of oil bearing reservoirs before its exploitation

Energy Technology Data Exchange (ETDEWEB)

Cubric, S

1971-10-01

The study deals with the application of Van Everdingen and Hurst's method to prediction of water influx from aquifer into an oil-bearing part of a reservoir. The examples show an influence of the factors affecting the water influx (time, permeability, ratio of radii of the aquifer, and oil-bearing part of reservoir.)

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

Energy Technology Data Exchange (ETDEWEB)

Boerresen, Knut Arne

1996-12-31

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

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

Energy Technology Data Exchange (ETDEWEB)

Boerresen, Knut Arne

1997-12-31

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

IMPROVING CO2 EFFICIENCY FOR RECOVERING OIL IN HETEROGENEOUS RESERVOIRS

Energy Technology Data Exchange (ETDEWEB)

Reid B. Grigg

2003-10-31

The second annual report of ''Improving CO{sub 2} Efficiency for Recovery Oil in Heterogeneous Reservoirs'' presents results of laboratory studies with related analytical models for improved oil recovery. All studies have been undertaken with the intention to optimize utilization and extend the practice of CO{sub 2} flooding to a wider range of reservoirs. Many items presented in this report are applicable to other interest areas: e.g. gas injection and production, greenhouse gas sequestration, chemical flooding, reservoir damage, etc. Major areas of studies include reduction of CO{sub 2} mobility to improve conformance, determining and understanding injectivity changes in particular injectivity loses, and modeling process mechanisms determined in the first two areas. Interfacial tension (IFT) between a high-pressure, high-temperature CO{sub 2} and brine/surfactant and foam stability are used to assess and screen surfactant systems. In this work the effects of salinity, pressure, temperature, surfactant concentration, and the presence of oil on IFT and CO{sub 2} foam stability were determined on the surfactant (CD1045{trademark}). Temperature, pressure, and surfactant concentration effected both IFT and foam stability while oil destabilized the foam, but did not destroy it. Calcium lignosulfonate (CLS) can be used as a sacrificial and an enhancing agent. This work indicates that on Berea sandstone CLS concentration, brine salinity, and temperature are dominant affects on both adsorption and desorption and that adsorption is not totally reversible. Additionally, CLS adsorption was tested on five minerals common to oil reservoirs; it was found that CLS concentration, salinity, temperature, and mineral type had significant effects on adsorption. The adsorption density from most to least was: bentonite > kaolinite > dolomite > calcite > silica. This work demonstrates the extent of dissolution and precipitation from co-injection of CO{sub 2} and

Quantifying Fracture Heterogeneity in Different Domains of Folded Carbonate Rocks to Improve Fractured Reservoir Analog Fluid Flow Models

NARCIS (Netherlands)

Bisdom, K.; Bertotti, G.; Gauthier, B.D.M.; Hardebol, N.J.

2013-01-01

Fluid flow in carbonate reservoirs is largely controlled by multiscale fracture networks. Significant variations of fracture network porosity and permeability are caused by the 3D heterogeneity of the fracture network characteristics, such as intensity, orientation and size. Characterizing fracture

Application of Integrated Reservoir Management and Reservoir Characterization to Optimize Infill Drilling

Energy Technology Data Exchange (ETDEWEB)

P. K. Pande

1998-10-29

Initial drilling of wells on a uniform spacing, without regard to reservoir performance and characterization, must become a process of the past. Such efforts do not optimize reservoir development as they fail to account for the complex nature of reservoir heterogeneities present in many low permeability reservoirs, and carbonate reservoirs in particular. These reservoirs are typically characterized by: o Large, discontinuous pay intervals o Vertical and lateral changes in reservoir properties o Low reservoir energy o High residual oil saturation o Low recovery efficiency

APPLICATION OF INTEGRATED RESERVOIR MANAGEMENT AND RESERVOIR CHARACTERIZATION

Energy Technology Data Exchange (ETDEWEB)

Jack Bergeron; Tom Blasingame; Louis Doublet; Mohan Kelkar; George Freeman; Jeff Callard; David Moore; David Davies; Richard Vessell; Brian Pregger; Bill Dixon; Bryce Bezant

2000-03-01

Reservoir performance and characterization are vital parameters during the development phase of a project. Infill drilling of wells on a uniform spacing, without regard to characterization does not optimize development because it fails to account for the complex nature of reservoir heterogeneities present in many low permeability reservoirs, especially carbonate reservoirs. These reservoirs are typically characterized by: (1) large, discontinuous pay intervals; (2) vertical and lateral changes in reservoir properties; (3) low reservoir energy; (4) high residual oil saturation; and (5) low recovery efficiency. The operational problems they encounter in these types of reservoirs include: (1) poor or inadequate completions and stimulations; (2) early water breakthrough; (3) poor reservoir sweep efficiency in contacting oil throughout the reservoir as well as in the nearby well regions; (4) channeling of injected fluids due to preferential fracturing caused by excessive injection rates; and (5) limited data availability and poor data quality. Infill drilling operations only need target areas of the reservoir which will be economically successful. If the most productive areas of a reservoir can be accurately identified by combining the results of geological, petrophysical, reservoir performance, and pressure transient analyses, then this ''integrated'' approach can be used to optimize reservoir performance during secondary and tertiary recovery operations without resorting to ''blanket'' infill drilling methods. New and emerging technologies such as geostatistical modeling, rock typing, and rigorous decline type curve analysis can be used to quantify reservoir quality and the degree of interwell communication. These results can then be used to develop a 3-D simulation model for prediction of infill locations. The application of reservoir surveillance techniques to identify additional reservoir ''pay'' zones

Identifying functional zones of denitrification in heterogeneous aquifer systems by numerical simulations - a case study

Science.gov (United States)

Jang, E.; Kalbacher, T.; He, W.; Shao, H.; Schueth, C.; Kolditz, O.

2014-12-01

Nitrate contamination in shallow groundwater is still one of the common problems in many countries. Because of its high solubility and anionic nature, nitrate can easily leach through soil and persist in groundwater for decades. High nitrate concentration has been suggested as a major cause of accelerated eutrophication, methemoglobinemia and gastric cancer. There are several factors influencing the fate of nitrate in groundwater system, which is e.g. distribution of N- sources to soil and groundwater, distribution and amount of reactive substances maintaining denitrification, rate of nitrate degradation and its kinetics, and geological characteristics of the aquifer. Nitrate transport and redox transformation processes are closely linked to complex and spatially distributed physical and chemical interaction, therefore it is difficult to predict and quantify in the field and laboratory experiment. Models can play a key role in elucidation of nitrate reduction pathway in groundwater system and in the design and evaluation of field tests to investigate in situ remediation technologies as well. The goal of the current study is to predict groundwater vulnerability to nitrate, to identify functional zones of denitrification in heterogeneous aquifer systems and to describe the uncertainty of the predictions due to scale effects. For this aim, we developed a kinetic model using multi-component mass transport code OpenGeoSys coupling with IPhreeqc module of the geochemical solver PHREEQC. The developed model included sequential aerobic and nitrate-based respiration, multi-Monod kinetics, multi-species biogeochemical reactions, and geological characteristics of the groundwater aquifer. Moreover water-rock interaction such as secondary mineral precipitation was also included in this model. In this presentation, we focused on the general modelling approach and present the simulation results of nitrate transport simulation in a hypothetical aquifer systems based on data from

LNAPL source zone delineation using soil gases in a heterogeneous silty-sand aquifer

Science.gov (United States)

Cohen, Grégory J. V.; Jousse, Florie; Luze, Nicolas; Höhener, Patrick; Atteia, Olivier

2016-09-01

Source delineation of hydrocarbon contaminated sites is of high importance for remediation work. However, traditional methods like soil core extraction and analysis or recent Membrane Interface Probe methods are time consuming and costly. Therefore, the development of an in situ method based on soil gas analysis can be interesting. This includes the direct measurement of volatile organic compounds (VOCs) in soil gas taken from gas probes using a PID (Photo Ionization Detector) and the analysis of other soil gases related to VOC degradation distribution (CH4, O2, CO2) or related to presence of Light Non-Aqueous Phase Liquid (LNAPL) as 222Rn. However, in widespread heterogeneous formations, delineation by gas measurements becomes more challenging. The objective of this study is twofold: (i) to analyse the potential of several in situ gas measurement techniques in comparison to soil coring for LNAPL source delineation at a heterogeneous contaminated site where the techniques might be limited by a low diffusion potential linked to the presence of fine sands and silts, and (ii) to analyse the effect of vertical sediment heterogeneities on the performance of these gas measurement methods. Thus, five types of gases were analysed: VOCs, their three related degradation products O2, CO2 and CH4 and 222Rn. Gas measurements were compared to independent LNAPL analysis by coring. This work was conducted at an old industrial site frequently contaminated by a Diesel-Fuel mixture located in a heterogeneous fine-grained aquifer. Results show that in such heterogeneous media migration of reactive gases like VOCs occurs only across small distances and the VOC concentrations sampled with gas probes are mainly related to local conditions rather than the presence of LNAPL below the gas probe. 222Rn is not well correlated with LNAPL because of sediment heterogeneity. Oxygen, CO2, and especially CH4, have larger lengths of diffusion and give the clearest picture for LNAPL presence at this

Lead Isotope Compositions of Acid Residues from Olivine-Phyric Shergottite Tissint: Implications for Heterogeneous Shergottite Source Reservoirs

Science.gov (United States)

Moriwaki, R.; Usui, T.; Yokoyama, T.; Simon, J. I.; Jones, J. H.

2015-01-01

Geochemical studies of shergottites suggest that their parental magmas reflect mixtures between at least two distinct geochemical source reservoirs, producing correlations between radiogenic isotope compositions and trace element abundances. These correlations have been interpreted as indicating the presence of a reduced, incompatible element- depleted reservoir and an oxidized, incompatible- element-enriched reservoir. The former is clearly a depleted mantle source, but there is ongoing debate regarding the origin of the enriched reservoir. Two contrasting models have been proposed regarding the location and mixing process of the two geochemical source reservoirs: (1) assimilation of oxidized crust by mantle derived, reduced magmas, or (2) mixing of two distinct mantle reservoirs during melting. The former requires the ancient Martian crust to be the enriched source (crustal assimilation), whereas the latter requires isolation of a long-lived enriched mantle domain that probably originated from residual melts formed during solidification of a magma ocean (heterogeneous mantle model). This study conducts Pb isotope and trace element concentration analyses of sequential acid-leaching fractions (leachates and the final residues) from the geochemically depleted olivine-phyric shergottite Tissint. The results suggest that the Tissint magma is not isotopically uniform and sampled at least two geochemical source reservoirs, implying that either crustal assimilation or magma mixing would have played a role in the Tissint petrogenesis.

A newly developed borehole flowmeter technology for heterogeneous aquifers

International Nuclear Information System (INIS)

Young, S.C.

1990-01-01

Extensive borehole flowmeter tests were performed at 37 fully-screened wells on a one-hectare test site to characterize the three-dimensional hydraulic conductivity field of an alluvial aquifer with a σ lnK of 4.7. During the site investigations, several major advancements with respect to borehole flowmeter technology were developed. The milestones included: (1) the development of a field-durable electromagnetic borehole flowmeter with a lower detection limit of 0.1 l/min; (2) the realization of the importance of the pumping rate with respect to the calculated value for the depth-averaged hydraulic conductivity; and (3) an evaluation of alternative methods for calculating the depth-averaged hydraulic conductivity. The predicted three-dimensional hydraulic conductivity field was compared to the results of 10 small-scale (3 to 7 m) tracer tests, information about the depositional history of the aquifer, and the results of three large-scale aquifer tests. The hydraulic conductivity data predict the major features of the tracer breakthrough curves, maps the outline of a former river meander in an aerial photograph, and leads to a geometric mean consistent with the average hydraulic conductivity of the aquifer. (Author) (14 refs., 15 figs., 2 tabs.)

Fine-Scale Spatial Heterogeneity in the Distribution of Waterborne Protozoa in a Drinking Water Reservoir.

Science.gov (United States)

Burnet, Jean-Baptiste; Ogorzaly, Leslie; Penny, Christian; Cauchie, Henry-Michel

2015-09-23

The occurrence of faecal pathogens in drinking water resources constitutes a threat to the supply of safe drinking water, even in industrialized nations. To efficiently assess and monitor the risk posed by these pathogens, sampling deserves careful design, based on preliminary knowledge on their distribution dynamics in water. For the protozoan pathogens Cryptosporidium and Giardia, only little is known about their spatial distribution within drinking water supplies, especially at fine scale. Two-dimensional distribution maps were generated by sampling cross-sections at meter resolution in two different zones of a drinking water reservoir. Samples were analysed for protozoan pathogens as well as for E. coli, turbidity and physico-chemical parameters. Parasites displayed heterogeneous distribution patterns, as reflected by significant (oo)cyst density gradients along reservoir depth. Spatial correlations between parasites and E. coli were observed near the reservoir inlet but were absent in the downstream lacustrine zone. Measurements of surface and subsurface flow velocities suggest a role of local hydrodynamics on these spatial patterns. This fine-scale spatial study emphasizes the importance of sampling design (site, depth and position on the reservoir) for the acquisition of representative parasite data and for optimization of microbial risk assessment and monitoring. Such spatial information should prove useful to the modelling of pathogen transport dynamics in drinking water supplies.

Nonpoint source solute transport normal to aquifer bedding in heterogeneous, Markov chain random fields

Science.gov (United States)

Zhang, Hua; Harter, Thomas; Sivakumar, Bellie

2006-06-01

Facies-based geostatistical models have become important tools for analyzing flow and mass transport processes in heterogeneous aquifers. Yet little is known about the relationship between these latter processes and the parameters of facies-based geostatistical models. In this study, we examine the transport of a nonpoint source solute normal (perpendicular) to the major bedding plane of an alluvial aquifer medium that contains multiple geologic facies, including interconnected, high-conductivity (coarse textured) facies. We also evaluate the dependence of the transport behavior on the parameters of the constitutive facies model. A facies-based Markov chain geostatistical model is used to quantify the spatial variability of the aquifer system's hydrostratigraphy. It is integrated with a groundwater flow model and a random walk particle transport model to estimate the solute traveltime probability density function (pdf) for solute flux from the water table to the bottom boundary (the production horizon) of the aquifer. The cases examined include two-, three-, and four-facies models, with mean length anisotropy ratios for horizontal to vertical facies, ek, from 25:1 to 300:1 and with a wide range of facies volume proportions (e.g., from 5 to 95% coarse-textured facies). Predictions of traveltime pdfs are found to be significantly affected by the number of hydrostratigraphic facies identified in the aquifer. Those predictions of traveltime pdfs also are affected by the proportions of coarse-textured sediments, the mean length of the facies (particularly the ratio of length to thickness of coarse materials), and, to a lesser degree, the juxtapositional preference among the hydrostratigraphic facies. In transport normal to the sedimentary bedding plane, traveltime is not lognormally distributed as is often assumed. Also, macrodispersive behavior (variance of the traveltime) is found not to be a unique function of the conductivity variance. For the parameter range

Numerical simulation of the environmental impact of hydraulic fracturing of tight/shale gas reservoirs on near-surface groundwater: Background, base cases, shallow reservoirs, short-term gas, and water transport

Science.gov (United States)

Reagan, Matthew T; Moridis, George J; Keen, Noel D; Johnson, Jeffrey N

2015-01-01

Hydrocarbon production from unconventional resources and the use of reservoir stimulation techniques, such as hydraulic fracturing, has grown explosively over the last decade. However, concerns have arisen that reservoir stimulation creates significant environmental threats through the creation of permeable pathways connecting the stimulated reservoir with shallower freshwater aquifers, thus resulting in the contamination of potable groundwater by escaping hydrocarbons or other reservoir fluids. This study investigates, by numerical simulation, gas and water transport between a shallow tight-gas reservoir and a shallower overlying freshwater aquifer following hydraulic fracturing operations, if such a connecting pathway has been created. We focus on two general failure scenarios: (1) communication between the reservoir and aquifer via a connecting fracture or fault and (2) communication via a deteriorated, preexisting nearby well. We conclude that the key factors driving short-term transport of gas include high permeability for the connecting pathway and the overall volume of the connecting feature. Production from the reservoir is likely to mitigate release through reduction of available free gas and lowering of reservoir pressure, and not producing may increase the potential for release. We also find that hydrostatic tight-gas reservoirs are unlikely to act as a continuing source of migrating gas, as gas contained within the newly formed hydraulic fracture is the primary source for potential contamination. Such incidents of gas escape are likely to be limited in duration and scope for hydrostatic reservoirs. Reliable field and laboratory data must be acquired to constrain the factors and determine the likelihood of these outcomes. Key Points: Short-term leakage fractured reservoirs requires high-permeability pathways Production strategy affects the likelihood and magnitude of gas release Gas release is likely short-term, without additional driving forces PMID

The effect of soil heterogeneity on ATES performance

Science.gov (United States)

Sommer, W.; Rijnaarts, H.; Grotenhuis, T.; van Gaans, P.

2012-04-01

Due to an increasing demand for sustainable energy, application of Aquifer Thermal Energy Storage (ATES) is growing rapidly. Large-scale application of ATES is limited by the space that is available in the subsurface. Especially in urban areas, suboptimal performance is expected due to thermal interference between individual wells of a single system, or interference with other ATES systems or groundwater abstractions. To avoid thermal interference there are guidelines on well spacing. However, these guidelines, and also design calculations, are based on the assumption of a homogeneous subsurface, while studies report a standard deviation in logpermeability of 1 to 2 for unconsolidated aquifers (Gelhar, 1993). Such heterogeneity may create preferential pathways, reducing ATES performance due to increased advective heat loss or interference between ATES wells. The role of hydraulic heterogeneity of the subsurface related to ATES performance has received little attention in literature. Previous research shows that even small amounts of heterogeneity can result in considerable uncertainty in the distribution of thermal energy in the subsurface and an increased radius of influence (Ferguson, 2007). This is supported by subsurface temperature measurements around ATES wells, which suggest heterogeneity gives rise to preferential pathways and short-circuiting between ATES wells (Bridger and Allen, 2010). Using 3-dimensional stochastic heat transport modeling, we quantified the influence of heterogeneity on the performance of a doublet well energy storage system. The following key parameters are varied to study their influence on thermal recovery and thermal balance: 1) regional flow velocity, 2) distance between wells and 3) characteristics of the heterogeneity. Results show that heterogeneity at the scale of a doublet ATES system introduces an uncertainty up to 18% in expected thermal recovery. The uncertainty increases with decreasing distance between ATES wells. The

Effect of heterogeneity in a horizontal well with multiple fractures on the long term forecast in shale gas reservoirs

Energy Technology Data Exchange (ETDEWEB)

Nobakht, M.; Ambrose, R.; Clarkson, C.R. [Society of Petroleum Engineers (Canada)

2011-07-01

Multiple fracture horizontal wells (MFHWs) are the most popular type of method used for exploiting shale gas reservoirs. When analyzing MFHW's a homogeneous completion model is often used, but this rarely occurs in the field. This paper develops a hybrid method for forecasting MFHWs based on a heterogeneous completion and investigates the effect of completion heterogeneity on production forecasts. First, a current forecasting method for homogeneous completions was modified for heterogeneous completions. The new forecasting method was then validated using a numerical simulation. A relationship between Arps' hyperbolic decline exponent and the heterogeneity of a completion for a particular case was then developed. Lastly, a field case was analyzed to compare the impact of forecasting with and without taking a heterogeneous completion into consideration. Through analysis and simulations this paper found that the long-term forecast of MFHWs can be greatly impacted should heterogeneity of the completion be ignored.

Comparison of stochastic and regression based methods for quantification of predictive uncertainty of model-simulated wellhead protection zones in heterogeneous aquifers

DEFF Research Database (Denmark)

Christensen, Steen; Moore, C.; Doherty, J.

2006-01-01

accurate and required a few hundred model calls to be computed. (b) The linearized regression-based interval (Cooley, 2004) required just over a hundred model calls and also appeared to be nearly correct. (c) The calibration-constrained Monte-Carlo interval (Doherty, 2003) was found to be narrower than......For a synthetic case we computed three types of individual prediction intervals for the location of the aquifer entry point of a particle that moves through a heterogeneous aquifer and ends up in a pumping well. (a) The nonlinear regression-based interval (Cooley, 2004) was found to be nearly...... the regression-based intervals but required about half a million model calls. It is unclear whether or not this type of prediction interval is accurate....

Probabilistic human health risk assessment of degradation-related chemical mixtures in heterogeneous aquifers: Risk statistics, hot spots, and preferential channels

Science.gov (United States)

Henri, Christopher V.; Fernàndez-Garcia, Daniel; de Barros, Felipe P. J.

2015-06-01

The increasing presence of toxic chemicals released in the subsurface has led to a rapid growth of social concerns and the need to develop and employ models that can predict the impact of groundwater contamination on human health risk under uncertainty. Monitored natural attenuation is a common remediation action in many contamination cases. However, natural attenuation can lead to the production of daughter species of distinct toxicity that may pose challenges in pollution management strategies. The actual threat that these contaminants pose to human health depends on the interplay between the complex structure of the geological media and the toxicity of each pollutant byproduct. This work addresses human health risk for chemical mixtures resulting from the sequential degradation of a contaminant (such as a chlorinated solvent) under uncertainty through high-resolution three-dimensional numerical simulations. We systematically investigate the interaction between aquifer heterogeneity, flow connectivity, contaminant injection model, and chemical toxicity in the probabilistic characterization of health risk. We illustrate how chemical-specific travel times control the regime of the expected risk and its corresponding uncertainties. Results indicate conditions where preferential flow paths can favor the reduction of the overall risk of the chemical mixture. The overall human risk response to aquifer connectivity is shown to be nontrivial for multispecies transport. This nontriviality is a result of the interaction between aquifer heterogeneity and chemical toxicity. To quantify the joint effect of connectivity and toxicity in health risk, we propose a toxicity-based Damköhler number. Furthermore, we provide a statistical characterization in terms of low-order moments and the probability density function of the individual and total risks.

Hydrodynamic framework of Saharan Triassic aquifers in South Tunisia and Algeria

Science.gov (United States)

Dhia, H. Ben; Chiarelli, A.

The main characteristics of the lower Triassic in the Saharan part of Tunisia are presented. This first study of the aquifer is made possible because of data available from numerous petroleum wells that exist in the region. The results show that the reservoir is of importance for either geothermal energy recovering or human water needs; especially since its salinity lies in the range 2 g/l to 60 g/l. Along the Tunisian-Llibyan frontier, because of its pressure and salinity (<3 g/l), the aquifer can be used for regional needs. The study also shows that the salinity gradient (SE-NW) increases orthogonally to the runoff direction (SW-NE). This phenomenon was unexpected and it is necessary to consider the aquifer in its regional North African framework and to include its Algerian part to understand it; when the salinity and potentiometric maps include both countries, a regional pattern is evident. Furthermore, a correspondence is noted between the salinity variations and the percentage of detritic elements in the reservoir. Salinity increases toward the NW, while the detritic elements decrease in that direction. Zones with salt content lower than 5 g/l seem to be related to good reservoirs and shales, that are rich in sands, and carbonates. The aquifer water supply is primarily linked to gravity flow and secondarily to compaction flow.

Characterization of aquifer heterogeneity using Cyclostratigraphy and geophysical methods in the upper part of the Karstic Biscayne Aquifer, Southeastern Florida

Science.gov (United States)

Cunningham, Kevin J.; Carlson, Janine L.; Wingard, G. Lynn; Robinson, Edward; Wacker, Michael A.

2004-01-01

This report identifies and characterizes candidate ground-water flow zones in the upper part of the shallow, eogenetic karst limestone of the Biscayne aquifer in the Lake Belt area of north-central Miami-Dade County using cyclostratigraphy, ground-penetrating radar (GPR), borehole geophysical logs, and continuously drilled cores. About 60 miles of GPR profiles were used to calculate depths to shallow geologic contacts and hydrogeologic units, image karst features, and produce qualitative views of the porosity distribution. Descriptions of the lithology, rock fabrics, and cyclostratigraphy, and interpretation of depositional environments of 50 test coreholes were linked to the geophysical interpretations to provide an accurate hydrogeologic framework. Molluscan and benthic foraminiferal paleontologic constraints guided interpretation of depositional environments represented by rockfabric facies. Digital borehole images were used to characterize and quantify large-scale vuggy porosity. Preliminary heat-pulse flowmeter data were coupled with the digital borehole image data to identify candidate ground-water flow zones. Combined results show that the porosity and permeability of the karst limestone of the Biscayne aquifer have a highly heterogeneous and anisotropic distribution that is mostly related to secondary porosity overprinting vertical stacking of rock-fabric facies within high-frequency cycles (HFCs). This distribution of porosity produces a dual-porosity system consisting of diffuse-carbonate and conduit flow zones. The nonuniform ground-water flow in the upper part of the Biscayne aquifer is mostly localized through secondary permeability, the result of solution-enlarged carbonate grains, depositional textures, bedding planes, cracks, root molds, and paleokarst surfaces. Many of the resulting pore types are classified as touching vugs. GPR, borehole geophysical logs, and whole-core analyses show that there is an empirical relation between formation porosity

Aquifer test interpretation using derivative analysis and diagnostic plots

Science.gov (United States)

Hernández-Espriú, Antonio; Real-Rangel, Roberto; Cortés-Salazar, Iván; Castro-Herrera, Israel; Luna-Izazaga, Gabriela; Sánchez-León, Emilio

2017-04-01

Pumping tests remain a method of choice to deduce fundamental aquifer properties and to assess well condition. In the oil and gas (O&G) industry, well testing has been the core technique in examining reservoir behavior over the last 50 years. The pressure derivative by Bourdet, it is perhaps, the most significant single development in the history of well test analysis. Recently, the so-called diagnostics plots (e.g. drawdown and drawdown derivative in a log-log plot) have been successfully tested in aquifers. However, this procedure is still underutilized by groundwater professionals. This research illustrates the applicability range, advantages and drawbacks (e.g. smoothing procedures) of diagnostic plots using field examples from a wide spectrum of tests (short/long tests, constant/variable flow rates, drawdown/buildup stages, pumping well/observation well) in dissimilar geological conditions. We analyze new and pre-existent aquifer tests in Mexico, USA, Canada, Germany, France and Saudi Arabia. In constant flow rate tests, our results show that derivative analysis is an easy, robust and powerful tool to assess near-borehole damage effects, formation heterogeneity, boundaries, flow regimes, infinite-acting radial stages, i.e., valid Theisian framework, and fracture-driven flow. In step tests, the effectiveness relies on high-frequency drawdown measurements. Moreover, we adapt O&G analytical solutions to cater for the conditions in groundwater systems. In this context, further parameters can be computed analytically from the plots, such as skin factor, head losses, wellbore storage, distance to the boundary, channel-aquifer and/or fracture zone width, among others. Therefore, diagnostic plots should be considered a mandatory tool for pumping tests analysis among hydrogeologists. This project has been supported by DGAPA (UNAM) under the research project PAPIIT IN-112815.

Monitoring and modelling of pumping-induced self-potentials for transmissivity estimation within a heterogeneous confined aquifer

Science.gov (United States)

DesRoches, Aaron J.; Butler, Karl E.

2016-12-01

Variations in self-potentials (SP) measured at surface during pumping of a heterogeneous confined fractured rock aquifer have been monitored and modelled in order to investigate capabilities and limitations of SP methods in estimating aquifer hydraulic properties. SP variations were recorded around a pumping well using an irregular grid of 31 non-polarizing Pb-PbCl2 that were referenced to a remote electrode and connected to a commercial multiplexer and digitizer/data logger through a passive lowpass filter on each channel. The lowpass filter reduced noise by a factor of 10 compared to levels obtained using the data logger's integration-based sampling method for powerline noise suppression alone. SP signals showed a linear relationship with water levels observed in the pumping and monitoring wells over the pumping period, with an apparent electrokinetic coupling coefficient of -3.4 mV · m-1. Following recent developments in SP methodology, variability of the SP response between different electrodes is taken as a proxy for lateral variations in hydraulic head within the aquifer and used to infer lateral variations in the aquifer's apparent transmissivity. In order to demonstrate the viability of this approach, SP is modelled numerically to determine its sensitivity to (i) lateral variations in the hydraulic conductivity of the confined aquifer and (ii) the electrical conductivity of the confining layer and conductive well casing. In all cases, SP simulated on the surface still varies linearly with hydraulic head modelled at the base on the confining layer although the apparent coupling coefficient changes to varying degrees. Using the linear relationship observed in the field, drawdown curves were inferred for each electrode location using SP variations observed over the duration of the pumping period. Transmissivity estimates, obtained by fitting the Theis model to inferred drawdown curves at all 31 electrodes, fell within a narrow range of (2.0-4.2) × 10-3 m2 �

Fortescue reservoir development and reservoir studies

Energy Technology Data Exchange (ETDEWEB)

Henzell, S.T.; Hicks, G.J.; Horden, M.J.; Irrgang, H.R.; Janssen, E.J.; Kable, C.W.; Mitchell, R.A.H.; Morrell, N.W.; Palmer, I.D.; Seage, N.W.

1985-03-01

The Fortescue field in the Gippsland Basin, offshore southeastern Australia is being developed from two platforms (Fortescue A and Cobia A) by Esso Australia Ltd. (operator) and BHP Petroleum. The Fortescue reservoir is a stratigraphic trap at the top of the Latrobe Group of sediments. It overlies the western flank of the Halibut and Cobia fields and is separated from them by a non-net sequence of shales and coals which form a hydraulic barrier between the two systems. Development drilling into the Fortescue reservoir commenced in April 1983 with production coming onstream in May 1983. Fortescue, with booked reserves of 44 stock tank gigalitres (280 million stock tank barrels) of 43/sup 0/ API oil, is the seventh major oil reservoir to be developed in the offshore Gippsland Basin by Esso/BHP. In mid-1984, after drilling a total of 20 exploration and development wells, and after approximately one year of production, a detailed three-dimensional, two-phase reservoir simulation study was performed to examine the recovery efficiency, drainage patterns, pressure performance and production rate potential of the reservoir. The model was validated by history matching an extensive suite of Repeat Formation Test (RFT) pressure data. The results confirmed the reserves basis, and demonstrated that the ultimate oil recovery from the reservoir is not sensitive to production rate. This result is consistent with studies on other high quality Latrobe Group reservoirs in the Gippsland Basin which contain undersaturated crudes and receive very strong water drive from the Basin-wide aquifer system. With the development of the simulation model during the development phase, it has been possible to more accurately define the optimal well pattern for the remainder of the development.

Intermediate-Scale Experimental Study to Improve Fundamental Understanding of Attenuation Capacity for Leaking CO2 in Heterogeneous Shallow Aquifers

Science.gov (United States)

Plampin, Michael R.; Porter, Mark L.; Pawar, Rajesh J.; Illangasekare, Tissa H.

2017-12-01

To assess the risks of Geologic Carbon Sequestration (GCS), it is crucial to understand the fundamental physicochemical processes that may occur if and when stored CO2 leaks upward from a deep storage reservoir into the shallow subsurface. Intermediate-scale experiments allow for improved understanding of the multiphase evolution processes that control CO2 migration behavior in the subsurface, because the boundary conditions, initial conditions, and porous media parameters can be better controlled and monitored in the laboratory than in field settings. For this study, a large experimental test bed was designed to mimic a cross section of a shallow aquifer with layered geologic heterogeneity. As water with aqueous CO2 was injected into the system to mimic a CO2-charged water leakage scenario, the spatiotemporal evolution of the multiphase CO2 plume was monitored. Similar experiments were performed with two different sand combinations to assess the relative effects of different types of geologic facies transitions on the CO2 evolution processes. Significant CO2 attenuation was observed in both scenarios, but by fundamentally different mechanisms. When the porous media layers had very different permeabilities, attenuation was caused by local accumulation (structural trapping) and slow redissolution of gas phase CO2. When the permeability difference between the layers was relatively small, on the other hand, gas phase continually evolved over widespread areas near the leading edge of the aqueous plume, which also attenuated CO2 migration. This improved process understanding will aid in the development of models that could be used for effective risk assessment and monitoring programs for GCS projects.

Predicting interwell heterogeneity in fluvial-deltaic reservoirs: Outcrop observations and applications of progressive facies variation through a depositional cycle

Energy Technology Data Exchange (ETDEWEB)

Knox, P.R.; Barton, M.D. [Univ. of Texas, Austin, TX (United States)

1997-08-01

Nearly 11 billion barrels of mobile oil remain in known domestic fluvial-deltaic reservoirs despite their mature status. A large percentage of this strategic resource is in danger of permanent loss through premature abandonment. Detailed reservoir characterization studies that integrate advanced technologies in geology, geophysics, and engineering are needed to identify remaining resources that can be targeted by near-term recovery methods, resulting in increased production and the postponement of abandonment. The first and most critical step of advanced characterization studies is the identification of reservoir architecture. However, existing subsurface information, primarily well logs, provides insufficient lateral resolution to identify low-permeability boundaries that exist between wells and compartmentalize the reservoir. Methods to predict lateral variability in fluvial-deltaic reservoirs have been developed on the basis of outcrop studies and incorporate identification of depositional setting and position within a depositional cycle. The position of a reservoir within the framework of a depositional cycle is critical. Outcrop studies of the Cretaceous Ferron Sandstone of Utah have demonstrated that the architecture and internal heterogeneity of sandstones deposited within a given depositional setting (for example, delta front) vary greatly depending upon whether they were deposited in the early, progradational part of a cycle or the late, retrogradational part of a cycle. The application of techniques similar to those used by this study in other fluvial-deltaic reservoirs will help to estimate the amount and style of remaining potential in mature reservoirs through a quicklook evaluation, allowing operators to focus characterization efforts on reservoirs that have the greatest potential to yield additional resources.

Two-phase flow visualization under reservoir conditions for highly heterogeneous conglomerate rock: A core-scale study for geologic carbon storage.

Science.gov (United States)

Kim, Kue-Young; Oh, Junho; Han, Weon Shik; Park, Kwon Gyu; Shinn, Young Jae; Park, Eungyu

2018-03-20

Geologic storage of carbon dioxide (CO 2 ) is considered a viable strategy for significantly reducing anthropogenic CO 2 emissions into the atmosphere; however, understanding the flow mechanisms in various geological formations is essential for safe storage using this technique. This study presents, for the first time, a two-phase (CO 2 and brine) flow visualization under reservoir conditions (10 MPa, 50 °C) for a highly heterogeneous conglomerate core obtained from a real CO 2 storage site. Rock heterogeneity and the porosity variation characteristics were evaluated using X-ray computed tomography (CT). Multiphase flow tests with an in-situ imaging technology revealed three distinct CO 2 saturation distributions (from homogeneous to non-uniform) dependent on compositional complexity. Dense discontinuity networks within clasts provided well-connected pathways for CO 2 flow, potentially helping to reduce overpressure. Two flow tests, one under capillary-dominated conditions and the other in a transition regime between the capillary and viscous limits, indicated that greater injection rates (potential causes of reservoir overpressure) could be significantly reduced without substantially altering the total stored CO 2 mass. Finally, the capillary storage capacity of the reservoir was calculated. Capacity ranged between 0.5 and 4.5%, depending on the initial CO 2 saturation.

Considering heterogeneities by transmissibilities averaging on adapted meshes in reservoir simulation; Prise en compte des heterogeneites par prise de moyenne des transmissivites sur maillages adaptes en simulation de reservoir

Energy Technology Data Exchange (ETDEWEB)

Urgelli, D

1998-10-16

Reservoir heterogeneity can be described using geostatistical models. But these models generate the heterogeneity on millions of fine grid blocks, which leads to prohibitive computational costs for reservoir simulations. In order to reduce the number of grid blocks, averaging techniques are needed to up-scale the fine scale permeabilities to the larger scales appropriate for flow simulation and engineering calculations. Grid block permeability up-scaling for numerical reservoir simulations has been discussed for a long time in the literature. It is now recognized that a full permeability tensor is needed to get an accurate reservoir description. But, the equivalent permeability on coarse grid blocks cannot be used directly on the numerical scheme. Usually, the harmonic average of the coarse grid block permeability is used for the transmissibility calculation, but it might cause a loss of accuracy. The purpose of this thesis is to present a new procedure for computing the equivalent transmissibility in the discretized flow equations on Cartesian grids and Corner Point Geometry grids. An application of this technique to a finite volume type numerical scheme is detailed. The principle of this technique is to calculate a permeability term on a shifted block placed between the two adjacent blocks where the transmissibility must be determined. At the field scale, the flow region can be divided into two types : a linear flow pattern with a low pressure gradient far from the wells and a radial flow pattern with a high pressure gradient in the vicinity of the wells. The radial flow region is usually more important for the prediction of production forecast, because it is directly related to the well. This was demonstrated theoretically and numerically for 2-D problem. The transmissibility up-scaling in radial flow pattern consists to determine the transmissibilities in the vicinity of wells and the numerical Productivity Index simultaneously. This new method called `shifted

Apport de la géostatistique à la description des stockages de gaz en aquifère Contribution of Geostatistics to Describing Aquifer Gas-Storage Reservoirs

Directory of Open Access Journals (Sweden)

Delhomme J. P.

2006-11-01

Full Text Available L'étude du comportement d'un réservoir de gaz en nappe aquifère réclame une connaissance aussi précise que possible des caractéristiques géométriques et pétrophysiques des couches réservoirs. Les moyens d'investigation sont de deux natures : - forages permettant une connaissance locale des roches réservoirs ; - mesures sismiques conduisant à une estimation approximative des cotes de certains repères stratigraphiques, en des points situés le long de profils. Les données recueillies sont donc, par nature, fragmentaires et discrètes : là où elles sont absentes, il y a lieu d'estimer les grandeurs étudiées en tenant compte au mieux de notre connaissance de leur variabilité spatiale. Ce problème d'interpolation optimale a donné lieu, depuis une vingtaine d'années, à l'élaboration et la mise en pratique d'un outil théorique particulièrement bien adapté aux besoins exprimés par les techniciens des sciences de la terre : la théorie des variables régionalisées due à G. Matheron. Des programmes informatiques mettant en oeuvre cette théorie sont actuellement opérationnels. Des exemples d'application en sont donnés : - tracé automatique de cartes structurales à partir des données de forages et des mesures sismiques ; - estimation des incertitudes de prévision sur les profondeurs ; - tracé de plusieurs variantes de carte compatibles avec les données ; - établissement d'éléments statistiques relatifs à une grandeur caractéristique d'un stockage : volume stockable par exemple ; - génération automatique des données nécessaires à la mise en oeuvre d'un modèle maillé de réservoir. Predicting and monitoring the behavior of an aquifer gas-storage reservoir requires as precise a knowledge as possible of the geometric and petrophysical properties of the reservoir layer. Two ways of obtaining this information can be given: (a Boreholes which provide local knowledge of the reservoir, and (b Seismic measurements

Characterization of oil and gas reservoir heterogeneity

Energy Technology Data Exchange (ETDEWEB)

1991-01-01

The objective of the cooperative research program is to characterize Alaskan reservoirs in terms of their reserves, physical and chemical properties, geologic configuration and structure, and the development potential. The tasks completed during this period include: (1) geologic reservoir description of Endicott Field; (2) petrographic characterization of core samples taken from selected stratigraphic horizons of the West Sak and Ugnu (Brookian) wells; (3) development of a polydispersed thermodynamic model for predicting asphaltene equilibria and asphaltene precipitation from crude oil-solvent mixtures, and (4) preliminary geologic description of the Milne Point Unit.

Kinetics of carbonate dissolution in CO2-saturated aqueous system at reservoir conditions

Science.gov (United States)

Peng, Cheng; Crawshaw, John P.; Maitland, Geoffrey; Trusler, J. P. Martin

2014-05-01

results of the study indicate that the rotating disc technique can allow accurate measurement of the carbonate dissolution rate under surface-reaction-controlled conditions, and that the carbonate dissolution rate typically increases with the increase of temperature, CO2 partial pressure and solution acidity. The study shows that the dissolution of carbonate in CO2-free acidic solutions can be described as a first order heterogeneous reaction; however, this model is not sufficient to describe the reaction kinetics of carbonate minerals in the (CO2 + H2O) system, particularly for high reactivity carbonates, such as calcite, at reservoir conditions. For these systems, both pH and the activity of CO2(aq) influence the dissolution rate. Based on the experimental results, kinetic models have been developed and parameterised to describe the dissolution of different carbonate minerals. The results of this study should facilitate more rigorous modelling of mineral dissolution in deep saline aquifers used for CO2 storage. We gratefully acknowledge the funding of QCCSRC provided jointly by Qatar Petroleum, Shell, and the Qatar Science & Technology Park. Keywords: Carbon Dioxide, Carbonate, High Pressure, High Temperature, Reaction Kinetics.

Seismic reflection and structuring characterization of deep aquifer system in the Dakhla syncline (Cap Bon, North-Eastern Tunisia)

Science.gov (United States)

Bellali, Abir; Jarraya Horriche, Faten; Gabtni, Hakim; Bédir, Mourad

2018-04-01

The Dakhla syncline is located in the North-Eastern Tunisia. It is bounded by Abd El Rahmene anticline to the North-West, El Haouaria Graben to the North-East, Grombalia Graben to the South-West and the Mediterranean Sea to the East. The main aquifer reservoirs of Dakhla syncline are constituted by stacks of fluvial to deltaic Neogene sequences and carbonates. The interpretation of eight seismic reflection profiles, calibrated by wire line logging data of three oil wells, hydraulic wells and geologic field sections highlighted the impact of tectonics on the structuring geometry of aquifers and their distribution in elevated structures and subsurface depressions. Lithostratigraphic correlations and seismic profiles analysis through the syncline show that the principal aquifers are thickest within the central and northern part of the study area and thinnest to the southern part of the syncline. Seismic sections shows that the fracture/fault pattern in this syncline is mainly concentrated along corridors with a major direction of NW-SE and secondary directions of N-S, E-W and NE-SW with different release. This is proved by the complexity structure of Eastern Tunisia, resulted from the interaction between the African and Eurasiatic plates. Isochron maps of aquifers systems exhibited the structuring of this syncline in sub-surface characterized by important lateral and vertical geometric and thickness variations. Seismic sections L1, L2, L3, L4, L5 and petroleum wells showed an heterogeneous multilayer aquifers of Miocene formed by the arrangement of ten sandstone bodies, separated by impermeable clay packages. Oligo-Miocene deposits correspond to the most great potential aquifers, with respectively an average transmissivity estimated: Somaa aquifer 6.5 10-4 m2/s, Sandstone level aquifer 2.6 10-3 m2/s, Beglia aquifer 1.1 10-3 m2/s, Ain Ghrab aquifer 1.3 10-4 m2/s and Oligocene aquifer 2 10-3 m2/s. The interpretation of spatial variations of seismic units and the

Support vector regression for porosity prediction in a heterogeneous reservoir: A comparative study

Science.gov (United States)

Al-Anazi, A. F.; Gates, I. D.

2010-12-01

In wells with limited log and core data, porosity, a fundamental and essential property to characterize reservoirs, is challenging to estimate by conventional statistical methods from offset well log and core data in heterogeneous formations. Beyond simple regression, neural networks have been used to develop more accurate porosity correlations. Unfortunately, neural network-based correlations have limited generalization ability and global correlations for a field are usually less accurate compared to local correlations for a sub-region of the reservoir. In this paper, support vector machines are explored as an intelligent technique to correlate porosity to well log data. Recently, support vector regression (SVR), based on the statistical learning theory, have been proposed as a new intelligence technique for both prediction and classification tasks. The underlying formulation of support vector machines embodies the structural risk minimization (SRM) principle which has been shown to be superior to the traditional empirical risk minimization (ERM) principle employed by conventional neural networks and classical statistical methods. This new formulation uses margin-based loss functions to control model complexity independently of the dimensionality of the input space, and kernel functions to project the estimation problem to a higher dimensional space, which enables the solution of more complex nonlinear problem optimization methods to exist for a globally optimal solution. SRM minimizes an upper bound on the expected risk using a margin-based loss function ( ɛ-insensitivity loss function for regression) in contrast to ERM which minimizes the error on the training data. Unlike classical learning methods, SRM, indexed by margin-based loss function, can also control model complexity independent of dimensionality. The SRM inductive principle is designed for statistical estimation with finite data where the ERM inductive principle provides the optimal solution (the

Geological exploration for a high-temperature aquifer thermal energy storage (HT-ATES) system: a case study from Oman

Science.gov (United States)

Winterleitner, Gerd; Schütz, Felina; Huenges, Ernst

2017-04-01

A collaborative research programme between the German Research Centre for Geoscience, Potsdam (GFZ) and The Research Council of Oman (TRC) is underway, which aims to develop and implement an innovative concept of a sustainable thermally driven cooling system in combination with a HT-ATES in northern Oman. The system will use an absorption chiller for cold supply, which nominally requires water of around 100°C as energy source. Solar collectors will provide this thermal energy and energy surpluses during daytimes will be stored to ensure a continuous operation of the cooling system. An integral part of this project is, therefore, the development of an efficient HT-ATES (100°C), which is based on temporary storage and recovery of thermal energy through hot water injection in subsurface aquifer horizons. Thus, an accurate thermal and fluid flow characterisation of potential reservoir horizons is essential to ensure optimal efficiency of the cooling system. The study area is located in the Al Khwad area, approximately 40 km to the west of Muscat. The area is characterised by a thick Cenozoic mixed carbonate-siliciclastic sedimentary succession, containing at least 3 aquifer horizons. We use a multidisciplinary approach for the initial ATES exploration and development phase, including traditional geological fieldwork dovetailed with virtual outcrop geology, thin-section analyses, geological modelling and reservoir fluid flow forecasting analyses. Our first results indicate two potential storage horizons: (1) a Miocene-aged clastic-dominated alluvial fan system and (2) an Eocene carbonate-dominated sequence. The alluvial fan system is characterised by a more than 300 m thick, coarse-clastic succession of coalesced individual fans. Thermal and hydraulic parameters are favourable for gravel and sandstone intervals but reservoir architecture is complex due to multiple generations of interconnecting fans with highly heterogeneous facies distributions. The Eocene carbonates

Application of Cutting-Edge 3D Seismic Attribute Technology to the Assessment of Geological Reservoirs for CO2 Sequestration

Energy Technology Data Exchange (ETDEWEB)

Christopher Liner; Jianjun Zeng; Po Geng Heather King Jintan Li; Jennifer Califf; John Seales

2010-03-31

The goals of this project were to develop innovative 3D seismic attribute technologies and workflows to assess the structural integrity and heterogeneity of subsurface reservoirs with potential for CO{sub 2} sequestration. Our specific objectives were to apply advanced seismic attributes to aide in quantifying reservoir properies and lateral continuity of CO{sub 2} sequestration targets. Our study area is the Dickman field in Ness County, Kansas, a type locality for the geology that will be encountered for CO{sub 2} sequestration projects from northern Oklahoma across the U.S. midcontent to Indiana and beyond. Since its discovery in 1962, the Dickman Field has produced about 1.7 million barrels of oil from porous Mississippian carbonates with a small structural closure at about 4400 ft drilling depth. Project data includes 3.3 square miles of 3D seismic data, 142 wells, with log, some core, and oil/water production data available. Only two wells penetrate the deep saline aquifer. Geological and seismic data were integrated to create a geological property model and a flow simulation grid. We systematically tested over a dozen seismic attributes, finding that curvature, SPICE, and ANT were particularly useful for mapping discontinuities in the data that likely indicated fracture trends. Our simulation results in the deep saline aquifer indicate two effective ways of reducing free CO{sub 2}: (a) injecting CO{sub 2} with brine water, and (b) horizontal well injection. A tuned combination of these methods can reduce the amount of free CO{sub 2} in the aquifer from over 50% to less than 10%.

Application of integrated reservoir management and reservoir characterization to optimize infill drilling, Class II

Energy Technology Data Exchange (ETDEWEB)

Bergeron, Jack; Blasingame, Tom; Doublet, Louis; Kelkar, Mohan; Freeman, George; Callard, Jeff; Moore, David; Davies, David; Vessell, Richard; Pregger, Brian; Dixon, Bill; Bezant, Bryce

2000-03-16

The major purpose of this project was to demonstrate the use of cost effective reservoir characterization and management tools that will be helpful to both independent and major operators for the optimal development of heterogeneous, low permeability carbonate reservoirs such as the North Robertson (Clearfork) Unit.

Geopressured-geothermal aquifers. Final contract report

Energy Technology Data Exchange (ETDEWEB)

1983-08-01

Task 1 is to provide petrophysical and reservoir analysis of wells drilled into geopressured-geothermal aquifers containing dissolved methane. The list of Design Wells and Wells of Opportunity analyzed: Fairfax Foster Sutter No. 2 (WOO), Pleasant Bayou No. 2 (Design), Amoco Fee No. 1 (Design), G.M. Koelemay No. 1 (WOO), Gladys McCall No. 1 (Design), P.R. Girouard No. 1 (WOO), and Crown Zellerbach No. 2 (WOO). Petrophysical and reservoir analysis of the above wells were performed based on availability of data. The analysis performed on each well, the assumptions made during simulation, and conclusions reached.

Application of conditional simulation of heterogeneous rock properties to seismic scattering and attenuation analysis in gas hydrate reservoirs

Science.gov (United States)

Huang, Jun-Wei; Bellefleur, Gilles; Milkereit, Bernd

2012-02-01

We present a conditional simulation algorithm to parameterize three-dimensional heterogeneities and construct heterogeneous petrophysical reservoir models. The models match the data at borehole locations, simulate heterogeneities at the same resolution as borehole logging data elsewhere in the model space, and simultaneously honor the correlations among multiple rock properties. The model provides a heterogeneous environment in which a variety of geophysical experiments can be simulated. This includes the estimation of petrophysical properties and the study of geophysical response to the heterogeneities. As an example, we model the elastic properties of a gas hydrate accumulation located at Mallik, Northwest Territories, Canada. The modeled properties include compressional and shear-wave velocities that primarily depend on the saturation of hydrate in the pore space of the subsurface lithologies. We introduce the conditional heterogeneous petrophysical models into a finite difference modeling program to study seismic scattering and attenuation due to multi-scale heterogeneity. Similarities between resonance scattering analysis of synthetic and field Vertical Seismic Profile data reveal heterogeneity with a horizontal-scale of approximately 50 m in the shallow part of the gas hydrate interval. A cross-borehole numerical experiment demonstrates that apparent seismic energy loss can occur in a pure elastic medium without any intrinsic attenuation of hydrate-bearing sediments. This apparent attenuation is largely attributed to attenuative leaky mode propagation of seismic waves through large-scale gas hydrate occurrence as well as scattering from patchy distribution of gas hydrate.

Assessing submarine groundwater discharge (SGD) and nitrate fluxes in highly heterogeneous coastal karst aquifers: Challenges and solutions

Science.gov (United States)

Montiel, Daniel; Dimova, Natasha; Andreo, Bartolomé; Prieto, Jorge; García-Orellana, Jordi; Rodellas, Valentí

2018-02-01

Groundwater discharge in coastal karst aquifers worldwide represents a substantial part of the water budget and is a main pathway for nutrient transport to the sea. Groundwater discharge to the sea manifests under different forms, making its assessment very challenging particularly in highly heterogeneous coastal systems karst systems. In this study, we present a methodology approach to identify and quantify four forms of groundwater discharge in a mixed lithology system in southern Spain (Maro-Cerro Gordo) that includes an ecologically protected coastal area comprised of karstic marble. We found that groundwater discharge to the sea occurs via: (1) groundwater-fed creeks, (2) coastal springs, (3) diffuse groundwater seepage through seabed sediments, and (4) submarine springs. We used a multi-method approach combining tracer techniques (salinity, 224Ra, and 222Rn) and direct measurements (seepage meters and flowmeters) to evaluate the discharge. Groundwater discharge via submarine springs was the most difficult to assess due to their depth (up to 15 m) and extensive development of the springs conduits. We determined that the total groundwater discharge over the 16 km of shoreline of the study area was at least 11 ± 3 × 103 m3 d-1 for the four types of discharge assessed. Groundwater-derived nitrate (NO3-) fluxes to coastal waters over ∼3 km (or 20%) in a highly populated and farmed section of Maro-Cerro Gordo was 641 ± 166 mol d-1, or ∼75% of the total NO3- loading in the study area. We demonstrate in this study that a multi-method approach must be applied to assess all forms of SGD and derived nutrient fluxes to the sea in highly heterogeneous karst aquifer systems.

Spatio-temporal variation in groundwater head affected by stratigraphic heterogeneity of the alluvial aquifer in Northwest India

Science.gov (United States)

van Dijk, W. M.; Joshi, S. K.; Densmore, A. L.; Jackson, C. R.; Sutanudjaja, E.; Lafare, A. E. A.; Gupta, S.; Mackay, J. D.; Mason, P. J.; Sinha, R.

2017-12-01

Groundwater is a primary source of freshwater in the alluvial aquifer system of northwestern India. Unsustainable exploitation of the groundwater resources has led to a regional hotspot in groundwater depletion. Rapid groundwater-level decline shows spatial variation, as the effects of various stresses, including precipitation, potential evapotranspiration and abstraction, are likely to be influenced by the stratigraphic and geomorphic heterogeneity between sediment fan and interfan areas (see Geomorphological map in Figure A). We used a transfer function-noise (TFN) time series approach to quantify the effect of the various stress components in the period 1974-2010, based on predefined impulse response functions (IRFs) of von Asmuth et al. (2008). The objective of this study was 1) to acquire the impulse response function of various stresses, 2) assess the spatial estimation parameter (the zeroth moment, M0) of the spatial development of the groundwater head and 3) relate the spatial M0 to the observed stratigraphic and geomorphic heterogeneity. We collected information on the groundwater head pre- and post-monsoon, the district-wise monthly precipitation and potential evapotranspiration, and we modeled the monthly abstraction rate using land-use information. The TFN identified the IRF of precipitation as well as abstraction. The IRF, summarized in the parameter M0, identified a hotspot for the abstraction stress (see M0 spatial map for abstraction in Figure B) at the margins of the Sutlej and Yamuna fans. No hotspot is observed for the precipitation stress, but the M0 for precipitation increases with distance from the Himalayan front. At larger distances from the Himalayan front, observed groundwater head rises cannot be explained by the IRFs for the abstraction and precipitation stresses. This is likely because the current TFN models do not account for other stresses, such as recharge by canal leakage, which are locally important. We conclude that the spatial

in Heterogeneous Media

Directory of Open Access Journals (Sweden)

Saeed Balouchi

2013-01-01

Full Text Available Fractured reservoirs contain about 85 and 90 percent of oil and gas resources respectively in Iran. A comprehensive study and investigation of fractures as the main factor affecting fluid flow or perhaps barrier seems necessary for reservoir development studies. High degrees of heterogeneity and sparseness of data have incapacitated conventional deterministic methods in fracture network modeling. Recently, simulated annealing (SA has been applied to generate stochastic realizations of spatially correlated fracture networks by assuming that the elastic energy of fractures follows Boltzmann distribution. Although SA honors local variability, the objective function of geometrical fracture modeling is defined for homogeneous conditions. In this study, after the introduction of SA and the derivation of the energy function, a novel technique is presented to adjust the model with highly heterogeneous data for a fractured field from the southwest of Iran. To this end, the regular object-based model is combined with a grid-based technique to cover the heterogeneity of reservoir properties. The original SA algorithm is also modified by being constrained in different directions and weighting the energy function to make it appropriate for heterogeneous conditions. The simulation results of the presented approach are in good agreement with the observed field data.

Reservoir resistivity characterization incorporating flow dynamics

KAUST Repository

Arango, Santiago

2016-04-07

Systems and methods for reservoir resistivity characterization are provided, in various aspects, an integrated framework for the estimation of Archie\\'s parameters for a strongly heterogeneous reservoir utilizing the dynamics of the reservoir are provided. The framework can encompass a Bayesian estimation/inversion method for estimating the reservoir parameters, integrating production and time lapse formation conductivity data to achieve a better understanding of the subsurface rock conductivity properties and hence improve water saturation imaging.

Reservoir resistivity characterization incorporating flow dynamics

KAUST Repository

Arango, Santiago; Sun, Shuyu; Hoteit, Ibrahim; Katterbauer, Klemens

2016-01-01

Systems and methods for reservoir resistivity characterization are provided, in various aspects, an integrated framework for the estimation of Archie's parameters for a strongly heterogeneous reservoir utilizing the dynamics of the reservoir are provided. The framework can encompass a Bayesian estimation/inversion method for estimating the reservoir parameters, integrating production and time lapse formation conductivity data to achieve a better understanding of the subsurface rock conductivity properties and hence improve water saturation imaging.

Heterogeneity-enhanced gas phase formation in shallow aquifers during leakage of CO2-saturated water from geologic sequestration sites

Science.gov (United States)

Plampin, Michael R.; Lassen, Rune N.; Sakaki, Toshihiro; Porter, Mark L.; Pawar, Rajesh J.; Jensen, Karsten H.; Illangasekare, Tissa H.

2014-12-01

A primary concern for geologic carbon storage is the potential for leakage of stored carbon dioxide (CO2) into the shallow subsurface where it could degrade the quality of groundwater and surface water. In order to predict and mitigate the potentially negative impacts of CO2 leakage, it is important to understand the physical processes that CO2 will undergo as it moves through naturally heterogeneous porous media formations. Previous studies have shown that heterogeneity can enhance the evolution of gas phase CO2 in some cases, but the conditions under which this occurs have not yet been quantitatively defined, nor tested through laboratory experiments. This study quantitatively investigates the effects of geologic heterogeneity on the process of gas phase CO2 evolution in shallow aquifers through an extensive set of experiments conducted in a column that was packed with layers of various test sands. Soil moisture sensors were utilized to observe the formation of gas phase near the porous media interfaces. Results indicate that the conditions under which heterogeneity controls gas phase evolution can be successfully predicted through analysis of simple parameters, including the dissolved CO2 concentration in the flowing water, the distance between the heterogeneity and the leakage location, and some fundamental properties of the porous media. Results also show that interfaces where a less permeable material overlies a more permeable material affect gas phase evolution more significantly than interfaces with the opposite layering.

Modelling of Pesticide Transport During An Injection Experiment In A Physical and Geochemical Heterogeneous Aquifer

Science.gov (United States)

Hojberg, A. L.; Engesgaard, P.; Bjerg, P. L.

The fate of selected pesticides under natural groundwater conditions was studied by natural gradient short and long term injection experiments in a shallow uncon- fined aerobic aquifer. Bentazone, DNOC, MCPP, dichlorprop, isoproturon, and BAM (dichlobenil metabolite) were injected in aqueous solution with bromide as a nonre- active tracer. The Bromide and pesticide plumes were sampled during the initial 25 m of migration in a dense monitoring net of multilevel samplers. The aquifer was physical and geochemical heterogeneous, which affected transport of several of the pesticides. A 3D reactive transport code was developed including one- and two-site linear/nonlinear equilibrium/nonequilibrium sorption and first-order as well as single Monod degradation kinetic coupled to microbial growth. Model simulations demon- strated that microbial growth was likely supported by the phenoxy acids MCPP and dichlorprop, while degradation of DNOC was adequately described by first-order degradation with no initial lag time. An observed vertical increase in pH was observed at the site and implemented in the transport code. The numerical analysis indicated that degradation of the three degradable pesticides may have been affected by vertical pH variations. Spatial variability in observed DNOC sorption was similarly suspected to be an effect of varying pH. pH dependency on DNOC sorption was confirmed by the model recognized by a match to observed breakthrough at the individual sampling points, when pH variation was included in the simulations.

Delta 37Cl and Characterisation of Petroleum-gas Reservoirs

Science.gov (United States)

Woulé Ebongué, V.; Jendrzejewski, N.; Walgenwitz, F.; Pineau, F.; Javoy, M.

2003-04-01

The geochemical characterisation of formation waters from oil/gas fields is used to detect fluid-flow barriers in reservoirs and to reconstruct the system dynamic. During the progression of the reservoir filling, the aquifer waters are pushed by hydrocarbons toward the reservoir bottom and their compositions evolve due to several parameters such as water-rock interactions, mixing with oil-associated waters, physical processes etc. The chemical and isotopic evolution of these waters is recorded in irreducible waters that have been progressively "fossilised" in the oil/gas column. Residual salts precipitated from these waters were recovered. Chloride being the most important dissolved anion in these waters and not involved in diagenetic reactions, its investigation should give insights into the different transport or mixing processes taking place in the sedimentary basin and point out to the formation waters origins. The first aim of our study was to test the Cl-RSA technique (Chlorine Residual Salts Analysis) based on the well-established Sr-RSA technique. The main studied area is a turbiditic sandstone reservoir located in the Lower Congo basin in Angola. Present-day aquifer waters, irreducible waters from sandstone and shale layers as well as drilling mud and salt dome samples were analysed. Formation waters (aquifer and irreducible trapped in shale) show an overall increase of chlorinity with depth. Their δ37Cl values range from -1.11 ppm to +2.30 ppm ± 0.05 ppm/ SMOC. Most Cl-RSA data as well as the δ37Cl obtained on a set of water samples (from different aquifers in the same area) are lower than -0.13 ppm with lower δ37Cl values at shallower depths. In a δ37Cl versus chlorinity diagram, they are distributed along a large range of chlorinity: 21 to 139 g/l, in two distinct groups. (1) Irreducible waters from one of the wells display a positive correlation between chlorinity and the δ37Cl values. (2) In contrary, the majority of δ37Cl measured on aquifers

CO2 interfacial properties: application to multiphase flow at reservoir conditions

International Nuclear Information System (INIS)

Chalbaud, C.

2007-07-01

In this work we deal with the interfacial properties of CO 2 at reservoir conditions with a special interest on deep saline aquifers. Each chapter of this dissertation represents a different physical scale studied with different experimental devices and simulation tools. The results obtained in the first part of this study represent a complete data set of brine-CO 2 interfacial tension at reservoir conditions. A semi-analytical equation is proposed in order to facilitate the work of reservoir engineers. The second deals with the interfacial properties at the pore scale using glass micro-models at different wettability conditions. This part shows the wetting behavior of CO 2 on hydrophobic or oil-wet solid surfaces. A pore network model was used for the interpretation and exploitation of these results. The third part corresponds to two different experimental approaches at the core scale at different wettability conditions associated to a modelling at flue Darcy scale. This part is a significant contribution to the validation of COORES compositional reservoir simulator developed by IFP. It has also allow us to estimate multiphase properties, Pc and kr, for brine-CO 2 systems at reservoir conditions. This study presents the necessary scales to model CO 2 storage in deep saline aquifers. (author)

Cenomanian-Turonian aquifer of central Israel, its development and possible use as a storage reservoir

Science.gov (United States)

Schneider, Robert

1964-01-01

The Cenomanian-Turonian formations constitute a highly permeable dolomite and limestone aquifer in central Israel. The aquifer is on the west limb of an anticlinorium that trends north-northeast. In places it may be as much as 800 meters thick, but in the report area, largely the foothills of the Judean-Ephraim Mountains where the water development is most intensive, its thickness is generally considerably less. In some places the aquifer occurs at or near the land surface, or it is covered by sandy and gravelly coastal-plain deposits. However, in a large part of the area, it is overlain by as much as 400 meters of relatively impermeable strata, and it is probably underlain by less permeable Lower Cretaceous strata. In general the aquifer water is under artesian pressure. The porosity of the aquifer is characterized mainly by solution channels and cavities produced by jointing and faulting. In addition to the generally high permeability of the aquifer, some regions, which probably coincide with ancient drainage patterns and (or) fault zones, have exceptionally high permeabilities. The source of most of the water in the aquifer is believed to be rain that falls on the foothills area. The westward movement of ground water from the mountainous outcrop areas appears to be impeded by a zone of low permeability which is related to structural and stratigraphic conditions along the western side of the mountains. Gradients of the piezometric surface are small, and the net direction of water movement is westward and northwestward under natural conditions. Locally, however, the flow pattern may be in other directions owing to spatial variations in permeability in the aquifer, the location of natural discharge outlets, and the relation of the aquifer to adjacent geologic formations. There probably is also a large vertical component of flow. Pumping has modified the flow pattern by producing several irregularly shaped shallow depressions in the piezometric surface although, to

On Fluid and Thermal Dynamics in a Heterogeneous CO2 Plume Geothermal Reservoir

Directory of Open Access Journals (Sweden)

Tianfu Xu

2017-01-01

Full Text Available CO2 is now considered as a novel heat transmission fluid to extract geothermal energy. It can achieve both the energy exploitation and CO2 geological sequestration. The migration pathway and the process of fluid flow within the reservoirs affect significantly a CO2 plume geothermal (CPG system. In this study, we built three-dimensional wellbore-reservoir coupled models using geological and geothermal conditions of Qingshankou Formation in Songliao Basin, China. The performance of the CPG system is evaluated in terms of the temperature, CO2 plume distribution, flow rate of production fluid, heat extraction rate, and storage of CO2. For obtaining a deeper understanding of CO2-geothermal system under realistic conditions, heterogeneity of reservoir’s hydrological properties (in terms of permeability and porosity is taken into account. Due to the fortissimo mobility of CO2, as long as a highly permeable zone exists between the two wells, it is more likely to flow through the highly permeable zone to reach the production well, even though the flow path is longer. The preferential flow shortens circulation time and reduces heat-exchange area, probably leading to early thermal breakthrough, which makes the production fluid temperature decrease rapidly. The analyses of flow dynamics of CO2-water fluid and heat may be useful for future design of a CO2-based geothermal development system.

Energy R and D. Geothermal energy and underground reservoirs; R et D energie. Geothermie et reservoirs souterrains

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-07-01

Geothermal energy appears as a viable economic alternative among the different renewable energy sources. The French bureau of geological and mining researches (BRGM) is involved in several research and development programs in the domain of geothermal energy and underground reservoirs. This document presents the content of 5 programs: the deep hot dry rock system of Soultz-sous-Forets (construction and testing of the scientific pilot, modeling of the reservoir structure), the development of low and high enthalpy geothermal energy in the French West Indies, the comparison of the geothermal development success of Bouillante (Guadeloupe, French West Indies) with the check of the geothermal development of Nyssiros (Greece) and Pantelleria (Italy), the development of the high enthalpy geothermal potentialities of Reunion Island, and the underground storage of CO{sub 2} emissions in geologic formations (deep aquifers, geothermal reservoirs, abandoned mines or oil reservoirs). (J.S.)

Assessment of a Geothermal Doublet in the Malm Aquifer Using a Push-Pull Tracer Test

Science.gov (United States)

Lafogler, Mark; Somogyi, Gabriella; Nießner, Reinhard; Baumann, Thomas

2013-04-01

Geothermal exploration of the Malm aquifer in Bavaria is highly successful. Data about the long-term operation, however, is still scarce, although detailed knowledge about the processes occurring in the aquifer is a key requirement to run geothermal facilities efficiently and economically. While there usually is a constant flow of data from the production well (temperatures, hydraulic data, hydrochemical conditions, gas composition) not even the temperatures in the immediate surrounding of the reinjection well are accessible or known. In 2011 the geothermal facility in Pullach was extended with a third geothermal well reaching into the Malm aquifer which is now used as a reinjection well. The former reinjection well was converted to a production well after 5 years of operation. This setting offers a unique opportunity to study the processes in the vicinity of a reinjection well and provides the data base to describe the hydraulic, thermal and hydrochemical performance of the reservoir. The viscosity of the reinjected cold water is increasing by 60% compared to the production well, thus one would expect an increase of the reinjection pressure as the cold water plume spreads around the reinjection well. Measurements, however, show a significant decrease of the reinjection pressure, suggesting processes in the aquifer which positively change the hydraulic properties and overcompensate the viscosity effects. Hydrochemical data and modeling indicate that a dissolution of the matrix along the flow pathways is responsible for the decreasing reinjection pressures. The change of the flow direction from reinjection to production was used to conduct a push-pull tracer test. Here, a series of fluorescent dye pulses was added to the reinjected water before the former reinjection well was shut down (push phase). These tracers included a conservative tracer (Fluorescein), surface-sensitive tracers (Eosin/Sulforhodamin B), and a NAPL-sensitive tracer (Na-Naphthionate). After

How to Recharge a Confined Aquifer: An Exploration of Geologic Controls on Groundwater Storage.

Science.gov (United States)

Maples, S.; Fogg, G. E.; Maxwell, R. M.; Liu, Y.

2017-12-01

Decreased snowpack storage and groundwater overdraft in California has increased interest in managed aquifer recharge (MAR) of excess winter runoff to the Central Valley aquifer system, which has unused storage capacity that far exceeds the state's surface reservoirs. Recharge to the productive, confined aquifer system remains a challenge due to the presence of nearly-ubiquitous, multiple silt and clay confining units that limit recharge pathways. However, previous studies have identified interconnected networks of sand and gravel deposits that bypass the confining units and accommodate rapid, high-volume recharge to the confined aquifer system in select locations. We use the variably-saturated, fully-integrated groundwater/surface-water flow code, ParFlow, in combination with a high-resolution, transition probability Markov-chain geostatistical model of the subsurface geologic heterogeneity of the east side of the Sacramento Valley, CA, to characterize recharge potential across a landscape that includes these geologic features. Multiple 180-day MAR simulations show that recharge potential is highly dependent on subsurface geologic structure, with a several order-of-magnitude range of recharge rates and volumes across the landscape. Where there are recharge pathways to the productive confined-aquifer system, pressure propagation in the confined system is widespread and rapid, with multi-kilometer lateral pressure propagation. Although widespread pressure propagation occurs in the confined system, only a small fraction of recharge volume is accommodated there. Instead, the majority of recharge occurs by filling unsaturated pore spaces. Where they outcrop at land surface, high-K recharge pathways fill rapidly, accommodating the majority of recharge during early time. However, these features become saturated quickly, and somewhat counterintuitively, the low-K silt and clay facies accommodate the majority of recharge volume during most of the simulation. These findings

Isotopic study of the Continental Intercalaire aquifer and its relationship with other aquifers of the northern Sahara

International Nuclear Information System (INIS)

Gonfiantini, R.; Sauzay, G.; Payne, B.R.; Conrad, G.; Fontes, J.Ch.

1974-01-01

The Northern Sahara contains several aquifers, the largest of which is that of the Continental Intercalaire formations. In its eastern part the aquifer is confined and presents a very homogeneous isotopic composition. The 14 C activity is low or zero except in the outcrop zones of the north (Saharan Atlas), the east (Dahar) and the south (Tinrhert), all of which are recharge zones. In these areas the isotopic composition does not differ appreciably from that of the old water in the confined part of the aquifer. In the western part, where the reservoir outcrops widely, the 14 C activities show the extent of the local recharge. The heavy isotope content indicates the overflow of the surface aquifer of the western Grand Erg into the Continental Intercalaire over the whole Gourara front. The mixtures thus formed pass under the Tademait and drain towards the Touat. In the resurgence zone of the Gulf of G abes in Tunisia the heavy-isotope content confirms the recharging of the aquifer of the Complex terminal by drainage of water from the Continental Intercalaire through the El-Hamma fault system. The water then runs eastwards, mixing with local contributions. The marine Miocene confined aquifer of Zarzis-Djerba in the Gulf of Gabes receives no contribution from the Continental Intercalaire. The water in the aquifer of the western Grand Erg indicates an evaporation mechanism, probably peculiar to the dune systems, which gives rise to heavy-isotope enrichment compared with the recharge of other types of formations. (author) [fr

Integration of advanced geoscience and engineering techniques to quantify interwell heterogeneity in reservoir models. Final report, September 29, 1993--September 30, 1996

Energy Technology Data Exchange (ETDEWEB)

Weiss, W.W.; Buckley, J.S.; Ouenes, A.

1997-05-01

The goal of this three-year project was to provide a quantitative definition of reservoir heterogeneity. This objective was accomplished through the integration of geologic, geophysical, and engineering databases into a multi-disciplinary understanding of reservoir architecture and associated fluid-rock and fluid-fluid interactions. This interdisciplinary effort integrated geological and geophysical data with engineering and petrophysical results through reservoir simulation to quantify reservoir architecture and the dynamics of fluid-rock and fluid-fluid interactions. An improved reservoir description allows greater accuracy and confidence during simulation and modeling as steps toward gaining greater recovery efficiency from existing reservoirs. A field laboratory, the Sulimar Queen Unit, was available for the field research. Several members of the PRRC staff participated in the development of improved reservoir description by integration of the field and laboratory data as well as in the development of quantitative reservoir models to aid performance predictions. Subcontractors from Stanford University and the University of Texas at Austin (UT) collaborated in the research and participated in the design and interpretation of field tests. The three-year project was initiated in September 1993 and led to the development and application of various reservoir description methodologies. A new approach for visualizing production data graphically was developed and implemented on the Internet. Using production data and old gamma rays logs, a black oil reservoir model that honors both primary and secondary performance was developed. The old gamma ray logs were used after applying a resealing technique, which was crucial for the success of the project. In addition to the gamma ray logs, the development of the reservoir model benefitted from an inverse Drill Stem Test (DST) technique which provided initial estimates of the reservoir permeability at different wells.

Oligo-Miocene reservoir sequence characterization and structuring in the Sisseb El Alem-Kalaa Kebira regions (Northeastern Tunisia)

Science.gov (United States)

Houatmia, Faten; Khomsi, Sami; Bédir, Mourad

2015-11-01

The Sisseb El Alem-Enfidha basin is located in the northeastern Tunisia, It is borded by Nadhour - Saouaf syncline to the north, Kairouan plain to the south, the Mediterranean Sea to the east and Tunisian Atlassic "dorsale" to the west. Oligocene and Miocene deltaic deposits present the main potential deep aquifers in this basin with high porosity (25%-30%). The interpretation of twenty seismic reflection profiles, calibrated by wire line logging data of twelve oil wells, hydraulic wells and geologic field sections highlighted the impact of tectonics on the structuring geometry of Oligo-Miocene sandstones reservoirs and their distribution in raised structures and subsurface depressions. Miocene seismostratigraphy analysis from Ain Ghrab Formation (Langhian) to the Segui Formation (Quaternary) showed five third-order seismic sequence deposits and nine extended lenticular sandy bodies reservoirs limited by toplap and downlap surfaces unconformities, Oligocene deposits presented also five third- order seismic sequences with five extended lenticular sandy bodies reservoirs. The Depth and the thickness maps of these sequence reservoir packages exhibited the structuring of this basin in sub-basins characterized by important lateral and vertical geometric and thichness variations. Petroleum wells wire line logging correlation with clay volume calculation showed an heterogeneous multilayer reservoirs of Oligocene and Miocene formed by the arrangement of fourteen sandstone bodies being able to be good reservoirs, separated by impermeable clay packages and affected by faults. Reservoirs levels correspond mainly to the lower system tract (LST) of sequences. Intensive fracturing by deep seated faults bounding the different sub-basins play a great role for water surface recharge and inter-layer circulations between affected reservoirs. The total pore volume of the Oligo-Miocene reservoir sandy bodies in the study area, is estimated to about 4 × 1012 m3 and equivalent to 4 �

Nutrient Removal during Stormwater Aquifer Storage and Recovery in an Anoxic Carbonate Aquifer.

Science.gov (United States)

Vanderzalm, Joanne L; Page, Declan W; Dillon, Peter J; Barry, Karen E; Gonzalez, Dennis

2018-03-01

Stormwater harvesting coupled to managed aquifer recharge (MAR) provides a means to use the often wasted stormwater resource while also providing protection of the natural and built environment. Aquifers can act as a treatment barrier within a multiple-barrier approach to harvest and use urban stormwater. However, it remains challenging to assess the treatment performance of a MAR scheme due to the heterogeneity of aquifers and MAR operations, which in turn influences water treatment processes. This study uses a probabilistic method to evaluate aquifer treatment performance based on the removal of total organic C (TOC), N, and P during MAR with urban stormwater in an anoxic carbonate aquifer. Total organic C, N, and P are represented as stochastic variables and described by probability density functions (PDFs) for the "injectant" and "recovery"; these injectant and recovery PDFs are used to derive a theoretical MAR removal efficiency PDF. Four long-term MAR sites targeting one of two tertiary carbonate aquifers (T1 and T2) were used to describe the nutrient removal efficiencies. Removal of TOC and total N (TN) was dominated by redox processes, with median removal of TOC between 50 and 60% at all sites and TN from 40 to 50% at three sites with no change at the fourth. Total P removal due to filtration and sorption accounted for median removal of 29 to 53%. Thus, the statistical method was able to characterize the capacity of the anoxic carbonate aquifer treatment barrier for nutrient removal, which highlights that aquifers can be an effective long-term natural treatment option for management of water quality, as well as storage of urban stormwater. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Enhancing drought resilience with conjunctive use and managed aquifer recharge in California and Arizona

Science.gov (United States)

Scanlon, Bridget R.; Reedy, Robert C.; Faunt, Claudia C.; Pool, Donald; Uhlman, Kristine

2016-03-01

Projected longer-term droughts and intense floods underscore the need to store more water to manage climate extremes. Here we show how depleted aquifers have been used to store water by substituting surface water use for groundwater pumpage (conjunctive use, CU) or recharging groundwater with surface water (managed aquifer recharge, MAR). Unique multi-decadal monitoring from thousands of wells and regional modeling datasets for the California Central Valley and central Arizona were used to assess CU and MAR. In addition to natural reservoir capacity related to deep water tables, historical groundwater depletion further expanded aquifer storage by ˜44 km3 in the Central Valley and by ˜100 km3 in Arizona, similar to or exceeding current surface reservoir capacity by up to three times. Local river water and imported surface water, transported through 100s of km of canals, is substituted for groundwater (≤15 km3 yr-1, CU) or is used to recharge groundwater (MAR, ≤1.5 km3 yr-1) during wet years shifting to mostly groundwater pumpage during droughts. In the Central Valley, CU and MAR locally reversed historically declining water-level trends, which contrasts with simulated net regional groundwater depletion. In Arizona, CU and MAR also reversed historically declining groundwater level trends in active management areas. These rising trends contrast with current declining trends in irrigated areas that lack access to surface water to support CU or MAR. Use of depleted aquifers as reservoirs could expand with winter flood irrigation or capturing flood discharges to the Pacific (0-1.6 km3 yr-1, 2000-2014) with additional infrastructure in California. Because flexibility and expanded portfolio options translate to resilience, CU and MAR enhance drought resilience through multi-year storage, complementing shorter term surface reservoir storage, and facilitating water markets.

Enhancing drought resilience with conjunctive use and managed aquifer recharge in California and Arizona

Science.gov (United States)

Scanlon, Bridget R.; Reedy, Robert C.; Faunt, Claudia; Pool, Donald R.; Uhlman, Kristine;

2016-01-01

Projected longer‐term droughts and intense floods underscore the need to store more water to manage climate extremes. Here we show how depleted aquifers have been used to store water by substituting surface water use for groundwater pumpage (conjunctive use, CU) or recharging groundwater with surface water (Managed Aquifer Recharge, MAR). Unique multi‐decadal monitoring from thousands of wells and regional modeling datasets for the California Central Valley and central Arizona were used to assess CU and MAR. In addition to natural reservoir capacity related to deep water tables, historical groundwater depletion further expanded aquifer storage by ~44 km3 in the Central Valley and by ~100 km3 in Arizona, similar to or exceeding current surface reservoir capacity by up to three times. Local river water and imported surface water, transported through 100s of km of canals, is substituted for groundwater (≤15 km3/yr, CU) or is used to recharge groundwater (MAR, ≤1.5 km3/yr) during wet years shifting to mostly groundwater pumpage during droughts. In the Central Valley, CU and MAR locally reversed historically declining water‐level trends, which contrasts with simulated net regional groundwater depletion. In Arizona, CU and MAR also reversed historically declining groundwater level trends in Active Management Areas. These rising trends contrast with current declining trends in irrigated areas that lack access to surface water to support CU or MAR. Use of depleted aquifers as reservoirs could expand with winter flood irrigation or capturing flood discharges to the Pacific (0 – 1.6 km3/yr, 2000–2014) with additional infrastructure in California. Because flexibility and expanded portfolio options translate to resilience, CU and MAR enhance drought resilience through multi‐year storage, complementing shorter term surface reservoir storage, and facilitating water markets.

HIGH RESOLUTION PREDICTION OF GAS INJECTION PROCESS PERFORMANCE FOR HETEROGENEOUS RESERVOIRS

Energy Technology Data Exchange (ETDEWEB)

Franklin M. Orr, Jr.

2004-05-01

This final technical report describes and summarizes results of a research effort to investigate physical mechanisms that control the performance of gas injection processes in heterogeneous reservoirs and to represent those physical effects in an efficient way in simulations of gas injection processes. The research effort included four main lines of research: (1) Efficient compositional streamline methods for 3D flow; (2) Analytical methods for one-dimensional displacements; (3) Physics of multiphase flow; and (4) Limitations of streamline methods. In the first area, results are reported that show how the streamline simulation approach can be applied to simulation of gas injection processes that include significant effects of transfer of components between phases. In the second area, the one-dimensional theory of multicomponent gas injection processes is extended to include the effects of volume change as components change phase. In addition an automatic algorithm for solving such problems is described. In the third area, results on an extensive experimental investigation of three-phase flow are reported. The experimental results demonstrate the impact on displacement performance of the low interfacial tensions between the gas and oil phases that can arise in multicontact miscible or near-miscible displacement processes. In the fourth area, the limitations of the streamline approach were explored. Results of an experimental investigation of the scaling of the interplay of viscous, capillary, and gravity forces are described. In addition results of a computational investigation of the limitations of the streamline approach are reported. The results presented in this report establish that it is possible to use the compositional streamline approach in many reservoir settings to predict performance of gas injection processes. When that approach can be used, it requires substantially less (often orders of magnitude) computation time than conventional finite difference

Reservoir Models for Gas Hydrate Numerical Simulation

Science.gov (United States)

Boswell, R.

2016-12-01

Scientific and industrial drilling programs have now providing detailed information on gas hydrate systems that will increasingly be the subject of field experiments. The need to carefully plan these programs requires reliable prediction of reservoir response to hydrate dissociation. Currently, a major emphasis in gas hydrate modeling is the integration of thermodynamic/hydrologic phenomena with geomechanical response for both reservoir and bounding strata. However, also critical to the ultimate success of these efforts is the appropriate development of input geologic models, including several emerging issues, including (1) reservoir heterogeneity, (2) understanding of the initial petrophysical characteristics of the system (reservoirs and seals), the dynamic evolution of those characteristics during active dissociation, and the interdependency of petrophysical parameters and (3) the nature of reservoir boundaries. Heterogeneity is ubiquitous aspect of every natural reservoir, and appropriate characterization is vital. However, heterogeneity is not random. Vertical variation can be evaluated with core and well log data; however, core data often are challenged by incomplete recovery. Well logs also provide interpretation challenges, particularly where reservoirs are thinly-bedded due to limitation in vertical resolution. This imprecision will extend to any petrophysical measurements that are derived from evaluation of log data. Extrapolation of log data laterally is also complex, and should be supported by geologic mapping. Key petrophysical parameters include porosity, permeability and it many aspects, and water saturation. Field data collected to date suggest that the degree of hydrate saturation is strongly controlled by/dependant upon reservoir quality and that the ratio of free to bound water in the remaining pore space is likely also controlled by reservoir quality. Further, those parameters will also evolve during dissociation, and not necessary in a simple

Benzene dynamics and biodegradation in alluvial aquifers affected by river fluctuations.

Science.gov (United States)

Batlle-Aguilar, J; Morasch, B; Hunkeler, D; Brouyère, S

2014-01-01

The spatial distribution and temporal dynamics of a benzene plume in an alluvial aquifer strongly affected by river fluctuations was studied. Benzene concentrations, aquifer geochemistry datasets, past river morphology, and benzene degradation rates estimated in situ using stable carbon isotope enrichment were analyzed in concert with aquifer heterogeneity and river fluctuations. Geochemistry data demonstrated that benzene biodegradation was on-going under sulfate reducing conditions. Long-term monitoring of hydraulic heads and characterization of the alluvial aquifer formed the basis of a detailed modeled image of aquifer heterogeneity. Hydraulic conductivity was found to strongly correlate with benzene degradation, indicating that low hydraulic conductivity areas are capable of sustaining benzene anaerobic biodegradation provided the electron acceptor (SO4 (2-) ) does not become rate limiting. Modeling results demonstrated that the groundwater flux direction is reversed on annual basis when the river level rises up to 2 m, thereby forcing the infiltration of oxygenated surface water into the aquifer. The mobilization state of metal trace elements such as Zn, Cd, and As present in the aquifer predominantly depended on the strong potential gradient within the plume. However, infiltration of oxygenated water was found to trigger a change from strongly reducing to oxic conditions near the river, causing mobilization of previously immobile metal species and vice versa. MNA appears to be an appropriate remediation strategy in this type of dynamic environment provided that aquifer characterization and targeted monitoring of redox conditions are adequate and electron acceptors remain available until concentrations of toxic compounds reduce to acceptable levels. © 2013, National Ground Water Association.

Investigating the effect of heterogeneity on infill wells

Directory of Open Access Journals (Sweden)

Mahmood Bagheri

2015-12-01

Full Text Available Abstract In recent years, improving oil recovery (IOR has become an important subject for the petroleum industry. One IOR method is infill drilling, which improves hydrocarbon recovery from virgin zones of the reservoir. Determining the appropriate location for the infill wells is very challenging and greatly depends on different factors such as the reservoir heterogeneity. This study aims to investigate the effect of reservoir heterogeneity on the location of infill well. In order to characterize the effect of heterogeneity on infill well locations, some geostatistical methods, e.g., sequential gaussian simulation, have been applied to generate various heterogeneity models. In particular, different correlation ranges (R were used to observe the effect of heterogeneity. Results revealed that an increase in correlation ranges will lead to (1 a higher field oil production total, and (2 a faster expansion of the drainage radius which consequently reduced the need for infill wells. The results of this study will help engineers to appropriately design infill drilling schemes.

Application of Reservoir Characterization and Advanced Technology to Improve Recovery and Economics in a Lower Quality Shallow Shelf Carbonate Reservoir

International Nuclear Information System (INIS)

Hickman, Scott T.; Justice James L.; Taylor, Archie R.

1999-01-01

The Class 2 Project at West Welch was designed to demonstrate the use of advanced technologies to enhance the economics of improved oil recovery (IOR) projects in lower quality Shallow Shelf Carbonate (SSC) reservoirs, resulting in recovery of additional oil that would otherwise be left in the reservoir at project abandonment. Accurate reservoir description is critical to the effective evaluation and efficient design of IOR projects in the heterogeneous SSC reservoirs

Aquifer storage and recovery: recent hydrogeological advances and system performance.

Science.gov (United States)

Maliva, Robert G; Guo, Weixing; Missimer, Thomas M

2006-12-01

Aquifer storage and recovery (ASR) is part of the solution to the global problem of managing water resources to meet existing and future freshwater demands. However, the metaphoric "ASR bubble" has been burst with the realization that ASR systems are more physically and chemically complex than the general conceptualization. Aquifer heterogeneity and fluid-rock interactions can greatly affect ASR system performance. The results of modeling studies and field experiences indicate that more sophisticated data collection and solute-transport modeling are required to predict how stored water will migrate in heterogeneous aquifers and how fluid-rock interactions will affect the quality of stored water. It has been well-demonstrated, by historic experience, that ASR systems can provide very large volumes of storage at a lesser cost than other options. The challenges moving forward are to improve the success rate of ASR systems, optimize system performance, and set expectations appropriately.

Geochemical detection of carbon dioxide in dilute aquifers

Directory of Open Access Journals (Sweden)

Aines Roger

2009-03-01

Full Text Available Abstract Background Carbon storage in deep saline reservoirs has the potential to lower the amount of CO2 emitted to the atmosphere and to mitigate global warming. Leakage back to the atmosphere through abandoned wells and along faults would reduce the efficiency of carbon storage, possibly leading to health and ecological hazards at the ground surface, and possibly impacting water quality of near-surface dilute aquifers. We use static equilibrium and reactive transport simulations to test the hypothesis that perturbations in water chemistry associated with a CO2 gas leak into dilute groundwater are important measures for the potential release of CO2 to the atmosphere. Simulation parameters are constrained by groundwater chemistry, flow, and lithology from the High Plains aquifer. The High Plains aquifer is used to represent a typical sedimentary aquifer overlying a deep CO2 storage reservoir. Specifically, we address the relationships between CO2 flux, groundwater flow, detection time and distance. The CO2 flux ranges from 103 to 2 × 106 t/yr (0.63 to 1250 t/m2/yr to assess chemical perturbations resulting from relatively small leaks that may compromise long-term storage, water quality, and surface ecology, and larger leaks characteristic of short-term well failure. Results For the scenarios we studied, our simulations show pH and carbonate chemistry are good indicators for leakage of stored CO2 into an overlying aquifer because elevated CO2 yields a more acid pH than the ambient groundwater. CO2 leakage into a dilute groundwater creates a slightly acid plume that can be detected at some distance from the leak source due to groundwater flow and CO2 buoyancy. pH breakthrough curves demonstrate that CO2 leaks can be easily detected for CO2 flux ≥ 104 t/yr within a 15-month time period at a monitoring well screened within a permeable layer 500 m downstream from the vertical gas trace. At lower flux rates, the CO2 dissolves in the aqueous phase

Geochemical detection of carbon dioxide in dilute aquifers.

Science.gov (United States)

Carroll, Susan; Hao, Yue; Aines, Roger

2009-03-26

Carbon storage in deep saline reservoirs has the potential to lower the amount of CO2 emitted to the atmosphere and to mitigate global warming. Leakage back to the atmosphere through abandoned wells and along faults would reduce the efficiency of carbon storage, possibly leading to health and ecological hazards at the ground surface, and possibly impacting water quality of near-surface dilute aquifers. We use static equilibrium and reactive transport simulations to test the hypothesis that perturbations in water chemistry associated with a CO2 gas leak into dilute groundwater are important measures for the potential release of CO2 to the atmosphere. Simulation parameters are constrained by groundwater chemistry, flow, and lithology from the High Plains aquifer. The High Plains aquifer is used to represent a typical sedimentary aquifer overlying a deep CO2 storage reservoir. Specifically, we address the relationships between CO2 flux, groundwater flow, detection time and distance. The CO2 flux ranges from 10(3) to 2 x 10(6) t/yr (0.63 to 1250 t/m2/yr) to assess chemical perturbations resulting from relatively small leaks that may compromise long-term storage, water quality, and surface ecology, and larger leaks characteristic of short-term well failure. For the scenarios we studied, our simulations show pH and carbonate chemistry are good indicators for leakage of stored CO2 into an overlying aquifer because elevated CO2 yields a more acid pH than the ambient groundwater. CO2 leakage into a dilute groundwater creates a slightly acid plume that can be detected at some distance from the leak source due to groundwater flow and CO2 buoyancy. pH breakthrough curves demonstrate that CO2 leaks can be easily detected for CO2 flux >or= 10(4) t/yr within a 15-month time period at a monitoring well screened within a permeable layer 500 m downstream from the vertical gas trace. At lower flux rates, the CO2 dissolves in the aqueous phase in the lower most permeable unit and does

Experimental investigation of geochemical and mineralogical effects of CO2 sequestration on flow characteristics of reservoir rock in deep saline aquifers

Science.gov (United States)

Rathnaweera, T. D.; Ranjith, P. G.; Perera, M. S. A.

2016-01-01

Interactions between injected CO2, brine, and rock during CO2 sequestration in deep saline aquifers alter their natural hydro-mechanical properties, affecting the safety, and efficiency of the sequestration process. This study aims to identify such interaction-induced mineralogical changes in aquifers, and in particular their impact on the reservoir rock’s flow characteristics. Sandstone samples were first exposed for 1.5 years to a mixture of brine and super-critical CO2 (scCO2), then tested to determine their altered geochemical and mineralogical properties. Changes caused uniquely by CO2 were identified by comparison with samples exposed over a similar period to either plain brine or brine saturated with N2. The results show that long-term reaction with CO2 causes a significant pH drop in the saline pore fluid, clearly due to carbonic acid (as dissolved CO2) in the brine. Free H+ ions released into the pore fluid alter the mineralogical structure of the rock formation, through the dissolution of minerals such as calcite, siderite, barite, and quartz. Long-term CO2 injection also creates a significant CO2 drying-out effect and crystals of salt (NaCl) precipitate in the system, further changing the pore structure. Such mineralogical alterations significantly affect the saline aquifer’s permeability, with important practical consequences for the sequestration process. PMID:26785912

Inverse modelling of aquifer parameters in basaltic rock with the help of pumping test method using MODFLOW software

Directory of Open Access Journals (Sweden)

Kanak Moharir

2017-11-01

The present study of estimation of aquifer factors such as transmissivity (T and storativity (S are vital for the evaluation of groundwater resources. There are several methods to estimate the accurate aquifer parameters (i.e. hydrograph analysis, pumping test, etc.. In initial days, these parameters are projected either by means of in-situ test or execution test on aquifer well samples carried in the laboratory. The simultaneous information on the hydraulic behavior of the well (borehole that provides on this method, the reservoir and the reservoir boundaries, are important for efficient aquifer and well data management and analysis. The most common in-situ test is pumping test performed on wells, which involves the measurement of the fall and increase of groundwater level with respect to time. The alteration in groundwater level (drawdown/recovery is caused due to pumping of water from the well. Theis (1935 was first to propose method to evaluate aquifer parameters from the pumping test on a bore well in a confined aquifer. It is essential to know the transmissivity (T = Kb, where b is the aquifer thickness; pumping flow rate, Q = TW (dh/dl flow through an aquifer and storativity (confined aquifer: S = bSs, unconfined: S = Sy, for the characterization of the aquifer parameters in an unknown area so as to predict the rate of drawdown of the groundwater table/potentiometric surface throughout the pumping test of an aquifer. The determination of aquifer's parameters is an important basis for groundwater resources evaluation, numerical simulation, development and protection as well as scientific management. For determining aquifer's parameters, pumping test is a main method. A case study shows that these techniques have been fast speed and high correctness. The results of parameter's determination are optimized so that it has important applied value for scientific research and geology engineering preparation.

Numerical modeling of fracking fluid and methane migration through fault zones in shale gas reservoirs

Science.gov (United States)

Taherdangkoo, Reza; Tatomir, Alexandru; Sauter, Martin

2017-04-01

Hydraulic fracturing operation in shale gas reservoir has gained growing interest over the last few years. Groundwater contamination is one of the most important environmental concerns that have emerged surrounding shale gas development (Reagan et al., 2015). The potential impacts of hydraulic fracturing could be studied through the possible pathways for subsurface migration of contaminants towards overlying aquifers (Kissinger et al., 2013; Myers, 2012). The intent of this study is to investigate, by means of numerical simulation, two failure scenarios which are based on the presence of a fault zone that penetrates the full thickness of overburden and connect shale gas reservoir to aquifer. Scenario 1 addresses the potential transport of fracturing fluid from the shale into the subsurface. This scenario was modeled with COMSOL Multiphysics software. Scenario 2 deals with the leakage of methane from the reservoir into the overburden. The numerical modeling of this scenario was implemented in DuMux (free and open-source software), discrete fracture model (DFM) simulator (Tatomir, 2012). The modeling results are used to evaluate the influence of several important parameters (reservoir pressure, aquifer-reservoir separation thickness, fault zone inclination, porosity, permeability, etc.) that could affect the fluid transport through the fault zone. Furthermore, we determined the main transport mechanisms and circumstances in which would allow frack fluid or methane migrate through the fault zone into geological layers. The results show that presence of a conductive fault could reduce the contaminant travel time and a significant contaminant leakage, under certain hydraulic conditions, is most likely to occur. Bibliography Kissinger, A., Helmig, R., Ebigbo, A., Class, H., Lange, T., Sauter, M., Heitfeld, M., Klünker, J., Jahnke, W., 2013. Hydraulic fracturing in unconventional gas reservoirs: risks in the geological system, part 2. Environ Earth Sci 70, 3855

Characterizing a complex aquifer system using geophysics, hydrodynamics and geochemistry: A new distribution of Miocene aquifers in the Zéramdine and Mahdia-Jébéniana blocks (east-central Tunisia)

Science.gov (United States)

Lachaal, Fethi; Bédir, Mourad; Tarhouni, Jamila; Gacha, Ayadi Ben; Leduc, Christian

2011-06-01

The Zéramdine and Mahdia-Jébéniana blocks are located in the Sahel region in east-central Tunisia. Active tectonics have divided the region into numerous sub-units, as result of multiple phases of distension and compression. The Miocene fluvio-deltaic sediment sandy layers have aquiferous capacities but their hydraulic properties are still unknown, due to the lack of investigation wells. This study proposes a new description of the regional hydrogeology of Miocene deposits. Seismic-reflection and wireline logging of petroleum and water wells were used to understand the structure and the geometry of the Miocene reservoirs. The groundwater flow and its relationship to the sedimentary and tectonic context were then identified by studying piezometry and hydrochemistry. Two Miocene deep aquifer systems were identified: (1) Zéramdine-Béni Hassen to the north and (2) Jébéniana-Ksour Essef to the south. These aquifers are separated by the Mahdia graben. Other major tectonic structures, such as the Zéramdine fault corridor, the Moknine graben, and the El-Jem half-graben represent lateral boundaries for these aquifers. Other deeper sandy and clayey-sandy reservoirs were also identified in the area. Their repartition, thickness and depth vary from one block to other. Hydrodynamics of the deep aquifers seems to be controlled by geological structures. Two independent compartments were identified: in the northern block groundwater flows from West to East and from Northwest to Southeast, while in the southern block it flows from Northwest to Southeast. Geochemical facies are of two types: Na-Ca-Cl-SO 4 for the Zéramdine-Béni Hassen deep aquifer and Na-Cl for the Jébéniana-Ksour Essef deep aquifer. The hydrodynamic and geochemical results confirm the sharing of the Miocene sediments into two aquifers.

Geothermal reservoirs. Position of slotted section of the tube casing

International Nuclear Information System (INIS)

Carotenuto, A.; Vanoli, L.; Casarosa, C.

1999-01-01

In the present work the authors have verified the influence of the position of slotted section casing on heat rate drawn by plants for exploitation of geothermal reservoirs that use heat exchangers placed at the bottom of the well (DHE). This study have been done modelling numerically the aquifer, by means of finite element method, evaluating the heat rate drawn by the heat exchanger at different position of the slotted section of the tube casing. Numerical calculations have allowed to show the influence of the main characteristics of the aquifer and of the main characteristics of the aquifer and of the plant on design of the slotted section of the tube casing. In particular, the authors have studied the influence of i) equivalent conductivity and permeability of the aquifer, ii) mass flow rate and the inlet and outlet aquifer temperature difference in the well, iii) the ratio between the length of the slotted section and the thickness of the geothermal layer, varying the position of the slotted section of the tube casing in the aquifer [it

Preliminary Groundwater Simulations To Compare Different Reconstruction Methods of 3-d Alluvial Heterogeneity

Science.gov (United States)

Teles, V.; de Marsily, G.; Delay, F.; Perrier, E.

Alluvial floodplains are extremely heterogeneous aquifers, whose three-dimensional structures are quite difficult to model. In general, when representing such structures, the medium heterogeneity is modeled with classical geostatistical or Boolean meth- ods. Another approach, still in its infancy, is called the genetic method because it simulates the generation of the medium by reproducing sedimentary processes. We developed a new genetic model to obtain a realistic three-dimensional image of allu- vial media. It does not simulate the hydrodynamics of sedimentation but uses semi- empirical and statistical rules to roughly reproduce fluvial deposition and erosion. The main processes, either at the stream scale or at the plain scale, are modeled by simple rules applied to "sediment" entities or to conceptual "erosion" entities. The model was applied to a several kilometer long portion of the Aube River floodplain (France) and reproduced the deposition and erosion cycles that occurred during the inferred climate periods (15 000 BP to present). A three-dimensional image of the aquifer was gener- ated, by extrapolating the two-dimensional information collected on a cross-section of the floodplain. Unlike geostatistical methods, this extrapolation does not use a statis- tical spatial analysis of the data, but a genetic analysis, which leads to a more realistic structure. Groundwater flow and transport simulations in the alluvium were carried out with a three-dimensional flow code or simulator (MODFLOW), using different rep- resentations of the alluvial reservoir of the Aube River floodplain: first an equivalent homogeneous medium, and then different heterogeneous media built either with the traditional geostatistical approach simulating the permeability distribution, or with the new genetic model presented here simulating sediment facies. In the latter case, each deposited entity of a given lithology was assigned a constant hydraulic conductivity value. Results of these

CO2/Brine transport into shallow aquifers along fault zones.

Science.gov (United States)

Keating, Elizabeth H; Newell, Dennis L; Viswanathan, Hari; Carey, J W; Zyvoloski, G; Pawar, Rajesh

2013-01-02

Unintended release of CO(2) from carbon sequestration reservoirs poses a well-recognized risk to groundwater quality. Research has largely focused on in situ CO(2)-induced pH depression and subsequent trace metal mobilization. In this paper we focus on a second mechanism: upward intrusion of displaced brine or brackish-water into a shallow aquifer as a result of CO(2) injection. Studies of two natural analog sites provide insights into physical and chemical mechanisms controlling both brackish water and CO(2) intrusion into shallow aquifers along fault zones. At the Chimayó, New Mexico site, shallow groundwater near the fault is enriched in CO(2) and, in some places, salinity is significantly elevated. In contrast, at the Springerville, Arizona site CO(2) is leaking upward through brine aquifers but does not appear to be increasing salinity in the shallow aquifer. Using multiphase transport simulations we show conditions under which significant CO(2) can be transported through deep brine aquifers into shallow layers. Only a subset of these conditions favor entrainment of salinity into the shallow aquifer: high aspect-ratio leakage pathways and viscous coupling between the fluid phases. Recognition of the conditions under which salinity is favored to be cotransported with CO(2) into shallow aquifers will be important in environmental risk assessments.

Is high-resolution inverse characterization of heterogeneous river bed hydraulic conductivities needed and possible?

Directory of Open Access Journals (Sweden)

W. Kurtz

2013-10-01

Full Text Available River–aquifer exchange fluxes influence local and regional water balances and affect groundwater and river water quality and quantity. Unfortunately, river–aquifer exchange fluxes tend to be strongly spatially variable, and it is an open research question to which degree river bed heterogeneity has to be represented in a model in order to achieve reliable estimates of river–aquifer exchange fluxes. This research question is addressed in this paper with the help of synthetic simulation experiments, which mimic the Limmat aquifer in Zurich (Switzerland, where river–aquifer exchange fluxes and groundwater management activities play an important role. The solution of the unsaturated–saturated subsurface hydrological flow problem including river–aquifer interaction is calculated for ten different synthetic realities where the strongly heterogeneous river bed hydraulic conductivities (L are perfectly known. Hydraulic head data (100 in the default scenario are sampled from the synthetic realities. In subsequent data assimilation experiments, where L is unknown now, the hydraulic head data are used as conditioning information, with the help of the ensemble Kalman filter (EnKF. For each of the ten synthetic realities, four different ensembles of L are tested in the experiments with EnKF; one ensemble estimates high-resolution L fields with different L values for each element, and the other three ensembles estimate effective L values for 5, 3 or 2 zones. The calibration of higher-resolution L fields (i.e. fully heterogeneous or 5 zones gives better results than the calibration of L for only 3 or 2 zones in terms of reproduction of states, stream–aquifer exchange fluxes and parameters. Effective L for a limited number of zones cannot always reproduce the true states and fluxes well and results in biased estimates of net exchange fluxes between aquifer and stream. Also in case only 10 head data are used for conditioning, the high

Numerical simulation of the environmental impact of hydraulic fracturing of tight/shale gas reservoirs on near-surface ground water: background, base cases, shallow reservoirs, short-term gas and water transport

Science.gov (United States)

Researchers examined gas and water transport between a deep tight shale gas reservoir and a shallow overlying aquifer in the two years following hydraulic fracturing, assuming a pre-existing connecting pathway.

Estimation of original reservoir fluid composition prior to aquifer boiling induced by well discharge. Kieki niso ryunyu ni okeru choryu sonai futto izen no chinetsu ryutai no kagaku soshiki no suiteiho

Energy Technology Data Exchange (ETDEWEB)

Seki, Y [Geological Survey of Japan, Tsukuba (Japan)

1991-07-29

A method for estimating chemical composition of original fluid before boiling from the composition of whole fluid flowing into a well is described for the case where an aquifer boiling has begun in a reservoir bed associated with discharge of geothermal fluid from the well (the enthalpy of fluid flowing into the well is larger than an enthalpy possessed by a hot fluid-phase saturated by steam at measured temperatures at flowing point). In this case, it is especially pointed out that the gas-liquid ratio at the well flow-in point becomes larger than the one at boiling. The boiling in the reservoir bed is modelled into two types. One is for larger coefficient of permeation in the reservoir bed where the discharge flow at the well is large, the temperature drop around the well is small, and the boiling is in single stage. The other is for smaller coefficient of permeation in the reservoir bed where the discharge flow and temperature drop are contrastive to the former case, and the boiling is in multi-stage. Calculation processes based on this boiling model are explained with calculation examples. 8 refs.,7 figs.

L'aquifère du bassin de la Mamora, Maroc: geometrie et ecoulements souterrainsThe aquifer of the Mamora Basin, Morocco: geometry and groundwater flow

Science.gov (United States)

Zouhri, L.

2001-05-01

The Mamora aquifer, in the northern Moroccan Meseta, constitutes the main regional water resource. Its impermeable basement is mostly composed of blue marls. The lithostratigraphy of the basin aquifer is characterised by a sequence of sandstones, sandy limestones, conglomerates and sandy clays. The structure of the basement of the Mamora aquifer, deduced from electrical resistivity measurements, allowed the hydrogeological behaviour of the reservoir, and the direction of the groundwater flow, to be established. The combination of the lithological, morphological, piezometric, geophysical and structural investigations revealed a northward thickening of the substrate with groundwater flow towards the Rharb (to the north) and towards the Atlantic Ocean (northwest). This 'multicriteria' approach enabled a structural model to be defined, which correlated well with the aquifer geometry and the groundwater flow. The variability of the hydrogeological units, and the northward thickening of the sedimentary facies, were controlled by northeast-southwest orientated faults, which affect their impermeability.

Reservoir Characterization, Production Characteristics, and Research Needs for Fluvial/Alluvial Reservoirs in the United States

Energy Technology Data Exchange (ETDEWEB)

Cole, E.L.; Fowler, M.L.; Jackson, S.R.; Madden, M.P.; Raw-Schatzinger, V.; Salamy, S.P.; Sarathi, P.; Young, M.A.

1999-04-28

The Department of Energy's (DOE's) Oil Recovery Field Demonstration Program was initiated in 1992 to maximize the economically and environmentally sound recovery of oil from known domestic reservoirs and to preserve access to this resource. Cost-shared field demonstration projects are being initiated in geology defined reservoir classes which have been prioritized by their potential for incremental recovery and their risk of abandonment. This document defines the characteristics of the fifth geological reservoir class in the series, fluvial/alluvial reservoirs. The reservoirs of Class 5 include deposits of alluvial fans, braided streams, and meandering streams. Deposit morphologies vary as a complex function of climate and tectonics and are characterized by a high degree of heterogeneity to fluid flow as a result of extreme variations in water energy as the deposits formed.

Assessing aquifer storage and recovery feasibility in the Gulf Coastal Plains of Texas

Directory of Open Access Journals (Sweden)

W. Benjamin Smith

2017-12-01

Full Text Available Study region: The Gulf Coast and Carrizo-Wilcox aquifer systems in the Gulf Coastal Plains of Texas. Study focus: Aquifer storage and recovery is a water storage alternative that is underutilized in Texas, a state with both long periods of drought and high intensity storms. Future water storage plans in Texas almost exclusively rely on surface reservoirs, subject to high evaporative losses. This study seeks to identify sites where aquifer storage and recovery (ASR may be successful, especially in recovery of injected waters, by analyzing publicly-available hydrogeologic data. Transmissivity, hydraulic gradient, well density, depth to aquifer, and depth to groundwater are used in a GIS-based index to determine feasibility of implementing an ASR system in the Gulf Coast and Carrizo-Wilcox aquifer systems. New hydrological insights for the region: Large regions of the central and northern Gulf Coast and the central and southern Carrizo-Wilcox aquifer systems are expected to be hydrologically feasible regions for ASR. Corpus Christi, Victoria, San Antonio, Bryan, and College Station are identified as possible cities where ASR would be a useful water storage strategy. Keywords: Aquifer storage and recovery (ASR, GIS, Gulf coast, Carrizo-Wilcox, Managed aquifer recharge (MAR

The use of the alluvial-lacustrine aquifer like a regulation reservoir. The example of the Oricola (Abruzzo); L'uso di acquiferi fluvio-lacustri quali serbatoi naturali di compenso. L'esempio della piana di Oricola (Abruzzo)

Energy Technology Data Exchange (ETDEWEB)

Celico, F. [Isernia Univ. degli Studi del Molise, Isernia (Italy). Dipt. di Scienze e Tecnologie per l' Ambiente e il Territorio; Habetswallner, F. [Naples Univ. Federico 2., Naples (Italy). Dipt. di Geofisica e Vulcanologia

2000-12-01

The hypothesis of using the Oricola Plane's alluvial-lacustrine aquifer (Abruzzo) like a regulation reservoir has been studied. The alluvial-lacustrine aquifer is constituted by silty and sandy deposits. The idea of using the aquifer like a regulation reservoir has been developed after the realization of a geophysical survey. Twenty six V.E.S. has been realised, with an AB distance of 300-400 metres. The volume of the reservoir, that is to say the volume of sand and gravel in the saturated medium, is about 3,8 x 10{sup 6} m{sup 3}. The results of this survey has been interpreted as a function of the drilling results near l'Immagine area. During the first test an effective porosity of 9,25% has been calculated for the medium-high portion of the reservoir. The results of a mathematical and physical model show that a mathematical transient model of groundwater flow can be implemented. [Italian] Lo studio condotto ha consentito di formulare un'ipotesi di utilizzo dell'aquifero fluvio-lacustre della piana di Oricola (Abruzzo) quale serbatoio naturale di compenso. E' stata infatti individuata una configurazione a catino della porzione centro-occidentale dell'aquifero, il cui volume e' pari a circa 3,8 x 10{sup 6} m{sup 3}. La determinazione sperimentale della porosita' efficace dei depositi fluvio-lacustri, oscillante tra il 4% ed il 9,5% circa, ha consentito a sua volta di calcolare il volume idrico invasato al di sotto del livello piezometrico di piena (pari a circa 0,28 x 10{sup 6} m{sup 3}), nonche' la sua variazione al progressivo decremento del livello di falda, prevalentemente indotto dagli emungimenti. Allo scopo di consentire una programmazione consapevole degli scenari di utilizzazione del serbatoio di compenso nel breve periodo, sono state messe a punto delle equazioni di correlazione tra le riserve permanenti presenti nel serbatoio stesso e la profondita' della falda dal piano campagna. Tutto quanto finora

Bedrock aquifers of eastern San Juan County, Utah

Science.gov (United States)

Avery, Charles

1986-01-01

This study is one of a series of studies appraising the waterbearing properties of the Navajo Sandstone and associated formations in southern Utah.  The study area is about 4,600 square miles, extending from the Utah-Arizona State line northward to the San Juan-Grand County line and westward from the Utah-Colorado State line to the longitude of about 109°50'.Some of the water-yielding formations are grouped into aquifer systems. The C aquifer is comprised of the DeChelly Sandstone Member of the Cutler Formation.  The P aquifer is comprised of the Cedar Mesa Member of the Cutler Formation and the undifferentiated Cutler Formation. The N aquifer is comprised of the sedimentary section that includes the Wingate Sandstone, Kayenta Formation, Navajo Sandstone, Carmel Formation, and Entrada sandstone.  The M aquifer is comprised of the Bluff Sandstone Member and other sandstone units of the Morrison Formation.  The D aquifer is comprised of the Burro Canyon Formation and Dakota Sandstone.  Discharge from the ground-water reservoir to the San Juan River between gaging stations at Four Corners and Mexican Hat is about 66 cubic feet per second.The N aquifer is the main aquifer in the study area. Recharge by infiltration of precipitation is estimated to be 25,000 acre-feet per year.  A major ground-water divide exists under the broad area east of Monticello.  The thickness of the N aquifer, where the sedimentary section is fully preserved and saturated, generally is 750 to 1,250 feet.   Hydraulic conductivity values obtained from aquifer tests range from 0.02 to 0.34 foot per day.  The total volume of water in transient storage is about 11 million acre-feet. Well discharge somewhat exceeded 2,340 acre-feet during 1981.  Discharge to the San Juan River from the N aquifer is estimated to be 6.9 cubic feet per second. Water quality ranges from a calcium bicarbonate to sodium chloride type water

Evaluation of potential gas clogging associated with managed aquifer recharge from a spreading basin, southwestern Utah, U.S.A.

Science.gov (United States)

Heilweil, Victor M.; Marston, Thomas

2013-01-01

Sand Hollow Reservoir in southwestern Utah, USA, is operated for both surface-water storage and managed aquifer recharge via infiltration from surface basin spreading to the underlying Navajo Sandstone. The total volume of estimated recharge from 2002 through 2011 was 131 Mm3., resulting in groundwater levels rising as much as 40 m. Hydraulic and hydrochemical data from the reservoir and various monitoring wells in Sand Hollow were used to evaluate the timing and location or reservoir recharge moving through the aquifer, along either potential clogging from trapped gases in pore throats, siltation, or algal mats. Several hyrdochemical tracers indicated this recharge had arrived at four monitoring wells located within about 300 m of the reservoir by 2012. At these wells, peak total dissolved-gas pressures exceeded two atmospheres (>1,500 mm mercury) and dissolved oxygen approached three times atmospherically equilibrated concentrations (>25 mg/L). these field parameters indicate that large amounts of gas trapped in pore spaces beneath the water table have dissolved. Lesser but notable increases in these dissolved-gas parameters (without increases in other indicators such as chloride-to-bromide ratios) at monitoring wells farther away (>300 m) indicate moderate amounts of in-situ sir entrapment and dissolution caused by the rise in regional groundwater levels. This is confirmed by hydrochemical difference between these sites and wells closer to the reservoir where recharge had already arrived. As the reservoir was being filled by 2002, managed aquifer recharge rates were initially very high (1.5 x 10-4 cm/s) with the vadose zone becoming saturated beneath and surrounding the reservoir. These rates declined to less than 3.5 x 10-6 cm/s during 2008. The 2002-08 decrease was likely associated with a declining regional hydraulic gradient and clogging. Increasing recharge rates during mid-2009 through 2010 may have been partly caused by dissolution of air bubbles

The thermal impact of aquifer thermal energy storage (ATES) systems: a case study in the Netherlands, combining monitoring and modeling

Science.gov (United States)

Visser, Philip W.; Kooi, Henk; Stuyfzand, Pieter J.

2015-05-01

Results are presented of a comprehensive thermal impact study on an aquifer thermal energy storage (ATES) system in Bilthoven, the Netherlands. The study involved monitoring of the thermal impact and modeling of the three-dimensional temperature evolution of the storage aquifer and over- and underlying units. Special attention was paid to non-uniformity of the background temperature, which varies laterally and vertically in the aquifer. Two models were applied with different levels of detail regarding initial conditions and heterogeneity of hydraulic and thermal properties: a fine-scale heterogeneity model which construed the lateral and vertical temperature distribution more realistically, and a simplified model which represented the aquifer system with only a limited number of homogeneous layers. Fine-scale heterogeneity was shown to be important to accurately model the ATES-impacted vertical temperature distribution and the maximum and minimum temperatures in the storage aquifer, and the spatial extent of the thermal plumes. The fine-scale heterogeneity model resulted in larger thermally impacted areas and larger temperature anomalies than the simplified model. The models showed that scattered and scarce monitoring data of ATES-induced temperatures can be interpreted in a useful way by groundwater and heat transport modeling, resulting in a realistic assessment of the thermal impact.

Identification des caractéristiques hydrogéologiques d'un réservoir en nappe aquifère Identification of the Hydrogeological Characteristics of an Aquifer Reservoir

Directory of Open Access Journals (Sweden)

Carriere J. F.

2006-11-01

Full Text Available Un des problèmes délicats de la reconnaissance d'un réservoir souterrain en nappe aquifère est l'identification de la distribution spatiale des paramètres hydrogéologiques. Une démarche usuelle consiste à interpréter des tests hydrauliques d'interférences ou un historique d'exploitation à l'aide d'un modèle maillé en identifiant les champs de paramètres qui décrivent l'aquifère (perméabilités, paramètres de réalimentation, etc. Cet ajustement doit tenir compte de toutes les sources d'information dont on dispose (tests de puits, connaissance géologique de la formation, etc. . Un programme d'ajustement automatique, répondant à ces critères, a été élaboré par l'Ecole des Mines de Paris et le Gaz de France. II permet d'interpréter les tests d'interférences et les premières injections expérimentales de gaz. Le calcul se déroule selon un processus d'optimisation en trois phases : - estimation géostatistique du champ de paramètres à identifier, à partir de valeurs ponctuelles connues et de valeurs ajustables en un nombre restreint de points choisis, dits pilotes ; - simulation des essais à l'aide d'un modèle monophasique bidimensionnel et comparaison des pressions calculées avec les valeurs mesurées ; - choix, par un algorithme de minimisation, des modifications à apporter aux valeurs des paramètres aux points pilotes. L'application à plusieurs cas réels a montré le grand intérêt de cette méthode. One of the delicate problems in the exploration of an underground aquifer reservoir is the identification of the spatial distribution of the hydrogeological parameters. The standard approach consists in interpreting hydraulic interference tests or the operating history of the formation with the help of a meshed model, by identifying the parameter fields describing the aquifer (permeabilities, feeding parameters, etc. . This approach must take all available information sources into account (well tests

Integrated reservoir assessment and characterization: Final report, October 1, 1985--September 30, 1988

Energy Technology Data Exchange (ETDEWEB)

Honarpour, M.; Szpakiewicz, M.; Sharma, B.; Chang, Ming-Ming; Schatzinger, R.; Jackson, S.; Tomutsa, L.; Maerefat, N.

1989-05-01

This report covers the development of a generic approach to reservoir characterization, the preliminary studies leading to the selection of an appropriate depositional system for detailed study, the application of outcrop studies to quantified reservoir characterization, and the construction of a quantified geological/engineering model used to screen the effects and scales of various geological heterogeneities within a reservoir. These heterogeneities result in large production/residual oil saturation contrasts over small distances. 36 refs., 124 figs., 38 tabs.

Methane production by Methanothermobacter thermautotrophicus to recover energy from carbon dioxide sequestered in geological reservoirs.

Science.gov (United States)

Kawaguchi, Hideo; Sakuma, Takahiro; Nakata, Yuiko; Kobayashi, Hajime; Endo, Keita; Sato, Kozo

2010-07-01

To recover energy from carbon dioxide sequestered in geological reservoirs, the geochemical effects of acidic and substrate- and nutrient-limiting conditions on methane production by the hydrogenotrophic methanogen Methanothermobacter thermautotrophicus were investigated in a simulated deep saline aquifer environment using formation water media retrieved from petroleum reservoirs. 2009 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Contamination risk and drinking water protection for a large-scale managed aquifer recharge site in a semi-arid karst region, Jordan

Science.gov (United States)

Xanke, Julian; Liesch, Tanja; Goeppert, Nadine; Klinger, Jochen; Gassen, Niklas; Goldscheider, Nico

2017-09-01

Karst aquifers in semi-arid regions are particularly threatened by surface contamination, especially during winter seasons when extremely variable rainfall of high intensities prevails. An additional challenge is posed when managed recharge of storm water is applied, since karst aquifers display a high spatial variability of hydraulic properties. In these cases, adapted protection concepts are required to address the interaction of surface water and groundwater. In this study a combined protection approach for the surface catchment of the managed aquifer recharge site at the Wala reservoir in Jordan and the downstream Hidan wellfield, which are both subject to frequent bacteriological contamination, is developed. The variability of groundwater quality was evaluated by correlating contamination events to rainfall, and to recharge from the reservoir. Both trigger increased wadi flow downstream of the reservoir by surface runoff generation and groundwater seepage, respectively. A tracer test verified the major pathway of the surface flow into the underground by infiltrating from pools along Wadi Wala. An intrinsic karst vulnerability and risk map was adapted to the regional characteristics and developed to account for the catchment separation by the Wala Dam and the interaction of surface water and groundwater. Implementation of the proposed protection zones for the wellfield and the reservoir is highly recommended, since the results suggest an extreme contamination risk resulting from livestock farming, arable agriculture and human occupation along the wadi. The applied methods can be transferred to other managed aquifer recharge sites in similar karstic environments of semi-arid regions.

Experimental and modeling results on geochemical impacts of leaking CO2 from subsurface storage reservoirs to an unconfined oxidizing carbonate aquifer

Science.gov (United States)

Qafoku, N. P.; Bacon, D. H.; Shao, H.; Lawter, A.; Wang, G.; Brown, C. F.

2013-12-01

Deep subsurface storage and sequestration of CO2 has been identified as a potential mitigation technique for rising atmospheric CO2 concentrations. Sequestered CO2 represents a potential risk to overlying aquifers if the CO2 leaks from the deep storage reservoir. Experimental and modeling work is required to evaluate risks to groundwater quality and develop a systematic understanding on how CO2 leakage may cause important changes in aquifer chemistry and mineralogy by promoting dissolution/precipitation, adsorption/desorption, and redox reactions. Solid materials (rocks and slightly weathered rocks) from an unconfined aquifer, i.e., the Edwards Aquifer in Texas, were used in this investigation. The experimental part consisted of: 1) wet chemical acid extractions (8M HNO3 solution at 90 0C); 2) batch experiments conducted at low solid to solution ratios to study time-dependent releases of major, minor and trace elements during periodic or continuous exposure to CO2 gas; 3) hydraulically saturated column experiments conducted under continuous and stop-flow conditions using a CO2 gas saturated synthetic groundwater; 4) pre- and post-treatment solid phase characterization studies. Major variables tested included reaction time (0-336 hours), CO2 flow rate (50 to 350 ml/min), brine concentration (0.1 and 1 M NaCl), rock type and particle size fraction. We are currently investigating the solution composition effects (i.e., presence of contaminants in the initial solution) on the fate and behavior of potential contaminants (As, Pb and Cd) in these systems. Results from the solid phase characterization studies showed that the mineralogy of the Edwards aquifer materials was dominated by calcite. Quartz and montmorillonite were also present in some samples. Acid extractions confirmed that the solid phase had appreciable amounts of potential contaminants (As, Cd, Cr, Cu, Pb and Zn). However, the results from the batch and column experiments demonstrated that these contaminants

Spatial and temporal heterogeneity in a subtropical reservoir and their effects over the benthic macroinvertebrate community

Directory of Open Access Journals (Sweden)

Frederico Guilherme de Souza Beghelli

2014-09-01

Full Text Available AIM: The objective of the present study was to demonstrate the influences of the environment spatial heterogeneity on benthic macroinvertebrates considering transverse and longitudinal gradients as also seasonality. METHODS: Four samplings were performed: two in the wet and two in the dry season in the riverine, transitional and lacustrine zones in the littoral and profundal regions of Itupararanga reservoir, SP, Brazil. Abiotic characterization of the water and of the sediment was performed. The biotic characterization was based on richness, dominance, diversity, and density of organisms, as well as on the relative abundance of predominant taxa. Two-way ANOSIM analyses were performed for both biotic and abiotic components, in order to test the significance of the differences in the longitudinal and transverse directions as well as of the differences between seasons. RESULTS: Compartmentalization was present in both directions, longitudinal and transverse. In a general way, the littoral region presented higher diversity values when compared with the profundal region, and the riverine zone presented high densities and high percentage of taxons, which usually indicate organic pollution. The differentiation between the transitional and lacustrine zones was determined mainly by taxonomic composition. Seasonality was also observed and the transportation of small particles, the entrance of nutrients, and the presence of macrophytes were considered as determinants for differentiation. CONCLUSIONS: Together, these results demonstrate the responses of benthic macroinvertebrate communities considering distinct sources of variation: longitudinal heterogeneity, determined by the increasing distance from the forming rivers that leads to a gradient of physical and chemical conditions; transverse heterogeneity, determined by the proximity with the land environment and depth differences. Seasonal heterogeneity was recorded during the period of this research and

The effect of heterogeneity on the character of density-driven natural convection of CO{sub 2} overlying a brine layer

Energy Technology Data Exchange (ETDEWEB)

Farajzadeh, R. [Shell International Exploration and Production, Houston, TX (United States); Ranganathan, P.; Zitha, P.L.J.; Bruining, J. [Delft Univ. of Technology, Delft (Netherlands)

2010-07-01

This paper investigated the effect of heterogeneity on the character of natural-convection flow of carbon dioxide (CO{sub 2}) in aquifers and on the dissolution rate of CO{sub 2} in brine, contributing to a better understanding of the effect of heterogeneity on CO{sub 2} mass transfer in aquifers, which is necessary for efficient storage of CO{sub 2} in aquifers. The aquifer permeability, which is in practice heterogeneous, largely governs the efficiency of mixing in density-driven natural convection. The aquifer's degree of permeability variance and the correlation length informs the character of flow-driven mixing processes. Numerical simulation was used to identify different flow regimes of a density-driven natural flow regime. Heterogeneous fields were generated using a spectral method that allows the use of power-law variograms. From the simulations it was observed that the rate of mass transfer of carbon dioxide (CO{sub 2}) into water is higher for heterogeneous media. The formulation of the physical model and related equations and the method for generating the permeability fields were described. The simulation results indicated that gravity-induced fingering is the dominant pattern in low heterogeneity, but fingering will not occur in realistic porous media. The results also showed that the permeability field structure dominates at moderate heterogeneity, and that the flow is dispersive at high heterogeneity when the correlation length of the field is small. Heterogeneous media facilitate a larger rate of CO{sub 2} dissolution than homogenous media, which means that the former can store larger volumes of CO{sub 2}. 49 refs., 3 tabs., 13 figs.

Ensemble-Based Data Assimilation in Reservoir Characterization: A Review

Directory of Open Access Journals (Sweden)

Seungpil Jung

2018-02-01

Full Text Available This paper presents a review of ensemble-based data assimilation for strongly nonlinear problems on the characterization of heterogeneous reservoirs with different production histories. It concentrates on ensemble Kalman filter (EnKF and ensemble smoother (ES as representative frameworks, discusses their pros and cons, and investigates recent progress to overcome their drawbacks. The typical weaknesses of ensemble-based methods are non-Gaussian parameters, improper prior ensembles and finite population size. Three categorized approaches, to mitigate these limitations, are reviewed with recent accomplishments; improvement of Kalman gains, add-on of transformation functions, and independent evaluation of observed data. The data assimilation in heterogeneous reservoirs, applying the improved ensemble methods, is discussed on predicting unknown dynamic data in reservoir characterization.

Relationship between tectonic structures and hydrogeochemical compartmentalization in aquifers: Example of the “Jeffara de Medenine” system, south–east Tunisia

Directory of Open Access Journals (Sweden)

Hayet Chihi

2015-09-01

The kriged maps of major-ion concentrations and of total dissolved solids in the aquifers were then analyzed and compared with the reservoir facies distribution for each compartment, the geometric characteristics of the aquifer, and the piezometric level trends. This allowed to characterize the hydraulic behavior of the Medenine fault and to understand the underlying physical and chemical processes having led to the spatial distribution of the geochemical properties, and thus, the hydrogeochemical functioning of the aquifers.

Application of Reservoir Characterization and Advanced Technology to Improve Recovery and Economics in a Lower Quality Shallow Shelf Carbonate Reservoir

International Nuclear Information System (INIS)

Taylor, Archie R.

1996-01-01

The Class 2 Project at West Welch was designed to demonstrate the use of advanced technologies to enhance the economics of improved oil recovery (IOR) projects in lower quality Shallow Shelf Carbonate (SSC) reservoirs, resulting in recovery of additional oil that would otherwise be left in the reservoir at project abandonment. Accurate reservoir description is critical to the effective evaluation and efficient design of IOR projects in the heterogeneous SSC reservoirs. Therefore, the majority of Budget Period 1 was devoted to reservoir characterization. Technologies being demonstrated include: (1) Advanced petrophysics; (2) Three dimensional (3-D) seismic; (3) Cross-well bore tomography; (4) Advanced reservoir simulation; (5) Carbon dioxide (CO 2 ) stimulation treatments; (6) Hydraulic fracturing design and monitoring; and (7) Mobility control agents

Use of high performance computing to examine the effectiveness of aquifer remediation

International Nuclear Information System (INIS)

Tompson, A.F.B.; Ashby, S.F.; Falgout, R.D.; Smith, S.G.; Fogwell, T.W.; Loosmore, G.A.

1994-06-01

Large-scale simulation of fluid flow and chemical migration is being used to study the effectiveness of pump-and-treat restoration of a contaminated, saturated aquifer. A three-element approach focusing on geostatistical representations of heterogeneous aquifers, high-performance computing strategies for simulating flow, migration, and reaction processes in large three-dimensional systems, and highly-resolved simulations of flow and chemical migration in porous formations will be discussed. Results from a preliminary application of this approach to examine pumping behavior at a real, heterogeneous field site will be presented. Future activities will emphasize parallel computations in larger, dynamic, and nonlinear (two-phase) flow problems as well as improved interpretive methods for defining detailed material property distributions

3D modeling of carbonates petro-acoustic heterogeneities

Science.gov (United States)

Baden, Dawin; Guglielmi, Yves; Saracco, Ginette; Marié, Lionel; Viseur, Sophie

2015-04-01

Characterizing carbonate reservoirs heterogeneity is a challenging issue for Oil & Gas Industry, CO2 sequestration and all kinds of fluid manipulations in natural reservoirs, due to the significant impact of heterogeneities on fluid flow and storage within the reservoir. Although large scale (> meter) heterogeneities such as layers petrophysical contrasts are well addressed by computing facies-based models, low scale (ultrasonic apparatus and using different sensors allowing acoustic characterization through a bandwidth varying from 50 to 500 kHz. Comprehensive measurements realized on each samples allowed statistical analyses of petro-acoustic properties such as attenuation, shear and longitudinal wave velocity. The cores properties (geological and acoustic facies) were modeled in 3D using photogrammetry and GOCAD geo-modeler. This method successfully allowed detecting and imaging in three dimensions differential diagenesis effects characterized by the occurrence of decimeter-scale diagenetic horizons in samples assumed to be homogeneous and/or different diagenetic sequences between shells filling and the packing matrix. We then discuss how small interfaces such as cracks, stylolithes and laminations which are also imaged may have guided these differential effects, considering that understanding the processes may be taken as an analogue to actual fluid drainage complexity in deep carbonate reservoir.

An evaluation of seepage gains and losses in Indian Creek Reservoir, Ada County, Idaho, April 2010–November 2011

Science.gov (United States)

Williams, Marshall L.; Etheridge, Alexandra B.

2013-01-01

The U.S. Geological Survey, in cooperation with the Idaho Department of Water Resources, conducted an investigation on Indian Creek Reservoir, a small impoundment in east Ada County, Idaho, to quantify groundwater seepage into and out of the reservoir. Data from the study will assist the Idaho Water Resources Department’s Comprehensive Aquifer Management Planning effort to estimate available water resources in Ada County. Three independent methods were utilized to estimate groundwater seepage: (1) the water-budget method; (2) the seepage-meter method; and (3) the segmented Darcy method. Reservoir seepage was quantified during the periods of April through August 2010 and February through November 2011. With the water-budget method, all measureable sources of inflow to and outflow from the reservoir were quantified, with the exception of groundwater; the water-budget equation was solved for groundwater inflow to or outflow from the reservoir. The seepage-meter method relies on the placement of seepage meters into the bottom sediments of the reservoir for the direct measurement of water flux across the sediment-water interface. The segmented-Darcy method utilizes a combination of water-level measurements in the reservoir and in adjacent near-shore wells to calculate water-table gradients between the wells and the reservoir within defined segments of the reservoir shoreline. The Darcy equation was used to calculate groundwater inflow to and outflow from the reservoir. Water-budget results provided continuous, daily estimates of seepage over the full period of data collection, while the seepage-meter and segmented Darcy methods provided instantaneous estimates of seepage. As a result of these and other difference in methodologies, comparisons of seepage estimates provided by the three methods are considered semi-quantitative. The results of the water-budget derived estimates of seepage indicate seepage to be seasonally variable in terms of the direction and magnitude

Geomorphic Controls on Aquifer Geometry in Northwestern India

Science.gov (United States)

van Dijk, W. M.; Densmore, A. L.; Sinha, R.; Gupta, S.; Mason, P. J.; Singh, A.; Joshi, S. K.; Nayak, N.; Kumar, M.; Shekhar, S.

2014-12-01

The Indo-Gangetic foreland basin suffers from one of the highest rates of groundwater extraction in the world, especially in the Indian states of Punjab, Haryana and Rajasthan. To understand the effects of this extraction on ground water levels, we must first understand the geometry and sedimentary architecture of the aquifer system, which in turn depend upon its geomorphic setting. We use satellite images and digital elevation models to map the geomorphology of the Sutlej and Yamuna river systems, while aquifer geometry is assessed using ~250 wells that extend to ~300 m depth in Punjab and Haryana. The Sutlej and Yamuna rivers have deposited large sedimentary fans at their outlets. Elongate downslope ridges on the fan surfaces form distributary networks that radiate from the Sutlej and Yamuna fan apices, and we interpret these ridges as paleochannel deposits associated with discrete fan lobes. Paleochannels picked out by soil moisture variations illustrate a complex late Quaternary history of channel avulsion and incision, probably associated with variations in monsoon intensity. Aquifer bodies on the Sutlej and Yamuna fans have a median thickness of 7 and 6 m, respectively, and follow a heavy-tailed distribution, probably because of stacked sand bodies. The percentage of aquifer material in individual lithologs decreases downstream, although the exponent on the thickness distribution remains the same, indicating that aquifer bodies decrease in number down fan but do not thin appreciably. Critically, the interfan area between the Sutlej and Yamuna fans has thinner aquifers and a lower proportion of aquifer material, despite its proximal location. Our data show that the Sutlej and Yamuna fan systems form the major aquifer systems in this area, and that their geomorphic setting therefore provides a first-order control on aquifer distribution and geometry. The large spatial heterogeneity of the system must be considered in any future aquifer management scheme.

APPLICATION OF RESERVOIR CHARACTERIZATION AND ADVANCED TECHNOLOGY TO IMPROVE RECOVERY AND ECONOMICS IN A LOWER QUALITY SHALLOW SHELF SAN ANDRES RESERVOIR

International Nuclear Information System (INIS)

Hickman, T. Scott

2003-01-01

The Class 2 Project at West Welch was designed to demonstrate the use of advanced technologies to enhance the economics of improved oil recovery (IOR) projects in lower quality Shallow Shelf Carbonate (SSC) reservoirs, resulting in recovery of additional oil that would otherwise be left in the reservoir at project abandonment. Accurate reservoir description is critical to the effective evaluation and efficient design of IOR projects in the heterogeneous SSC reservoirs. Therefore, the majority of Budget Period 1 was devoted to reservoir characterization. Technologies being demonstrated include: (1) Advanced petrophysics; (2) Three-dimensional (3-D) seismic; (3) Crosswell bore tomography; (4) Advanced reservoir simulation; (5) Carbon dioxide (CO 2 ) stimulation treatments; (6) Hydraulic fracturing design and monitoring; and (7) Mobility control agents

APPLICATION OF RESERVOIR CHARACTERIZATION AND ADVANCED TECHNOLOGY TO IMPROVE RECOVERY AND ECONOMICS IN A LOWER QUALITY SHALLOW SHELF SAN ANDRES RESERVOIR

International Nuclear Information System (INIS)

Raj Kumar; Keith Brown; Hickman, T. Scott; Justice, James J.

2000-01-01

The Class 2 Project at West Welch was designed to demonstrate the use of advanced technologies to enhance the economics of improved oil recovery (IOR) projects in lower quality Shallow Shelf Carbonate (SSC) reservoirs, resulting in recovery of additional oil that would otherwise be left in the reservoir at project abandonment. Accurate reservoir description is critical to the effective evaluation and efficient design of IOR projects in the heterogeneous SSC reservoirs. Therefore, the majority of Budget Period 1 was devoted to reservoir characterization. Technologies being demonstrated include: (1) Advanced petrophysics; (2) Three-dimensional (3-D) seismic; (3) Crosswell bore tomography; (4) Advanced reservoir simulation; (5) Carbon dioxide (CO 2 ) stimulation treatments; (6) Hydraulic fracturing design and monitoring; and (7) Mobility control agents

APPLICATION OF RESERVOIR CHARACTERIZATION AND ADVANCED TECHNOLOGY TO IMPROVE RECOVERY AND ECONOMICS IN A LOWER QUALITY SHALLOW SHELF SAN ANDRES RESERVOIR

International Nuclear Information System (INIS)

Hickman, T. Scott; Justice, James J.

2001-01-01

The Class 2 Project at West Welch was designed to demonstrate the use of advanced technologies to enhance the economics of improved oil recovery (IOR) projects in lower quality Shallow Shelf Carbonate (SSC) reservoirs, resulting in recovery of additional oil that would otherwise be left in the reservoir at project abandonment. Accurate reservoir description is critical to the effective evaluation and efficient design of IOR projects in the heterogeneous SSC reservoirs. Therefore, the majority of Budget Period 1 was devoted to reservoir characterization. Technologies being demonstrated include: (1) Advanced petrophysics; (2) Three-dimensional (3-D) seismic; (3) Crosswell bore tomography; (4) Advanced reservoir simulation; (5) Carbon dioxide (CO 2 ) stimulation treatments; (6) Hydraulic fracturing design and monitoring; and (7) Mobility control agents

APPLICATION OF RESERVOIR CHARACTERIZATION AND ADVANCED TECHNOLOGY TO IMPROVE RECOVERY AND ECONOMICS IN A LOWER QUALITY SHALLOW SHELF SAN ANDRES RESERVOIR

Energy Technology Data Exchange (ETDEWEB)

T. Scott Hickman; James J. Justice

2001-06-16

The Class 2 Project at West Welch was designed to demonstrate the use of advanced technologies to enhance the economics of improved oil recovery (IOR) projects in lower quality Shallow Shelf Carbonate (SSC) reservoirs, resulting in recovery of additional oil that would otherwise be left in the reservoir at project abandonment. Accurate reservoir description is critical to the effective evaluation and efficient design of IOR projects in the heterogeneous SSC reservoirs. Therefore, the majority of Budget Period 1 was devoted to reservoir characterization. Technologies being demonstrated include: (1) Advanced petrophysics; (2) Three-dimensional (3-D) seismic; (3) Crosswell bore tomography; (4) Advanced reservoir simulation; (5) Carbon dioxide (CO{sub 2}) stimulation treatments; (6) Hydraulic fracturing design and monitoring; and (7) Mobility control agents.

Contribution of environmental isotopes to the study of large aquifers in Morocco

International Nuclear Information System (INIS)

Kabbaj, A.; Zeryouhi, I.; Carlier, P.

1978-01-01

The geochemistry of environmental isotopes has been applied to several aquifers in Maroc, some of them quite large: Charf el Akab in the Tanger region, the Oum er Rbia basin and the Tadla aquifer, the free nappe of limnic limes tone in the Sais plane, and the lias limestone aquifer. The isotopic investigations on the basis of hydrogeochemical data have given more precise information on the supply conditions of these aquifers. The types of water of different origin from the Atlas or the phosphate plateau in the Sais plane and the Tadla basin have been distinguished, the supply from one aquifer to another Lias nappe which, via the flexures of the Sais plane, supplies the nappe of limic limestone has been assessed, the homogeneity or heterogeneity of these aquifers has been investigated as well as their impermeability, the Tadla aquifer and the special case of Charf el Akab compared with the marine region. The findings have proved the usefulness of these techniques and permitted a specification of the general conditions for their application. (orig.) [de

Relative influence of deposition and diagenesis on carbonate reservoir layering

Energy Technology Data Exchange (ETDEWEB)

Poli, Emmanuelle [Total E and P, Courbevoie (France); Javaux, Catherine [Total E and P, Pointe Noire (Congo)

2008-07-01

The architecture heterogeneities and petrophysical properties of carbonate reservoirs result from a combination of platform morphology, related depositional environments, relative sea level changes and diagenetic events. The reservoir layering built for static and dynamic modelling purposes should reflect the key heterogeneities (depositional or diagenetic) which govern the fluid flow patterns. The layering needs to be adapted to the goal of the modelling, ranging from full field computations of hydrocarbon volumes, to sector-based fine-scale simulations to test the recovery improvement. This paper illustrates various reservoir layering types, including schemes dominated by depositional architecture, and those more driven by the diagenetic overprint. The examples include carbonate platform reservoirs from different stratigraphic settings (Tertiary, Cretaceous, Jurassic and Permian) and different regions (Europe, Africa and Middle East areas). This review shows how significant stratigraphic surfaces (such as sequence boundaries or maximum flooding) with their associated facies shifts, can be often considered as key markers to constrain the reservoir layering. Conversely, how diagenesis (dolomitization and karst development), resulting in units with particular poroperm characteristics, may significantly overprint the primary reservoir architecture by generating flow units which cross-cut depositional sequences. To demonstrate how diagenetic processes can create reservoir bodies with geometries that cross-cut the depositional fabric, different types of dolomitization and karst development are illustrated. (author)

Characterization of dynamic change of Fan-delta reservoir properties in water-drive development

Energy Technology Data Exchange (ETDEWEB)

Wu Shenghe; Xiong Qihua; Liu Yuhong [Univ. of Petroleum Changping, Beijing (China)

1997-08-01

Fan-delta reservoir in Huzhuangji oil field of east China, is a typical highly heterogeneous reservoir. The oil field has been developed by water-drive for 10 years, but the oil recovery is less than 12%, and water cut is over 90%, resulting from high heterogeneity and serious dynamic change of reservoir properties. This paper aims at the study of dynamic change of reservoir properties in water-drive development. Through quantitative imaging analysis and mercury injection analysis of cores from inspection wells, the dynamic change of reservoir pore structure in water-drive development was studied. The results show that the {open_quotes}large pore channels{close_quotes} develop in distributary channel sandstone and become larger in water-drive development, resulting in more serious pore heterogeneity. Through reservoir sensitivity experiments, the rock-fluid reaction in water-drive development is studied. The results show the permeability of some distal bar sandstone and deserted channel sandstone becomes lower due to swelling of I/S clay minerals in pore throats. OD the other hand, the permeability of distributary channel and mouth bar sandstone become larger because the authigenic Koalinites in pore throats are flushed away with the increase of flow rate of injection water. Well-logging analysis of flooded reservoirs are used to study the dynamic change of reservoir properties in various flow units. The distribution of remaining oil is closely related to the types and distribution of flow units.

Modeling CO₂ Sequestration in Saline Aquifer and Depleted Oil Reservoir To Evaluate Regional CO₂ Sequestration Potential of Ozark Plateau Aquifer System, South-Central Kansas

Energy Technology Data Exchange (ETDEWEB)

Watney, W. Lynn [University Of Kansas Center For Research, Inc. Lawrence, KS (United States); Rush, Jason [University Of Kansas Center For Research, Inc. Lawrence, KS (United States); Raney, Jennifer [University Of Kansas Center For Research, Inc. Lawrence, KS (United States)

2014-09-30

1. Drilled, cored, and logged three wells to the basement and collecting more than 2,700 ft of conventional core; obtained 20 mⁱ² of multicomponent 3D seismic imaging and merged and reprocessed more than 125 mi² of existing 3D seismic data for use in modeling CO₂- EOR oil recovery and CO₂ storage in five oil fields in southern Kansas. 2. Determined the technical feasibility of injecting and sequestering CO₂ in a set of four depleted oil reservoirs in the Cutter, Pleasant Prairie South, Eubank, and Shuck fields in southwest Kansas; of concurrently recovering oil from those fields; and of quantifying the volumes of CO2 sequestered and oil recovered during the process. 3. Formed a consortium of six oil operating companies, five of which own and operate the four fields. The consortium became part of the Southwest Kansas CO₂-EOR Initiative for the purpose of sharing data, knowledge, and interest in understanding the potential for CO₂-EOR in Kansas. 4. Built a regional well database covering 30,000 mi² and containing stratigraphic tops from ~90,000 wells; correlated 30 major stratigraphic horizons; digitized key wells, including wireline logs and sample logs; and analyzed more than 3,000 drill stem tests to establish that fluid levels in deep aquifers below the Permian evaporites are not connected to the surface and therefore pressures are not hydrostatic. Connectivity with the surface aquifers is lacking because shale aquitards and impermeable evaporite layers consist of both halite and anhydrite. 5. Developed extensive web applications and an interactive mapping system that do the following: a. Facilitate access to a wide array of data obtained in the study, including core descriptions and analyses, sample logs, digital (LAS) well logs, seismic data, gravity and magnetics maps, structural and stratigraphic maps, inferred fault traces, earthquakes, Class I and II disposal wells, and

Modeling CO₂ Sequestration in Saline Aquifer and Depleted Oil Reservoir To Evaluate Regional CO₂ Sequestration Potential of Ozark Plateau Aquifer System, South-Central Kansas

Energy Technology Data Exchange (ETDEWEB)

Watney, W. Lynn [University Of Kansas Center For Research, Inc. Lawrence, KS (United States)

2014-09-30

1. Drilled, cored, and logged three wells to the basement and collecting more than 2,700 ft of conventional core; obtained 20 mⁱ² of multicomponent 3D seismic imaging and merged and reprocessed more than 125 mi² of existing 3D seismic data for use in modeling CO₂- EOR oil recovery and CO₂ storage in five oil fields in southern Kansas. 2. Determined the technical feasibility of injecting and sequestering CO₂ in a set of four depleted oil reservoirs in the Cutter, Pleasant Prairie South, Eubank, and Shuck fields in southwest Kansas; of concurrently recovering oil from those fields; and of quantifying the volumes of CO2 sequestered and oil recovered during the process. 3. Formed a consortium of six oil operating companies, five of which own and operate the four fields. The consortium became part of the Southwest Kansas CO₂-EOR Initiative for the purpose of sharing data, knowledge, and interest in understanding the potential for CO₂-EOR in Kansas. 4. Built a regional well database covering 30,000 mi² and containing stratigraphic tops from ~90,000 wells; correlated 30 major stratigraphic horizons; digitized key wells, including wireline logs and sample logs; and analyzed more than 3,000 drill stem tests to establish that fluid levels in deep aquifers below the Permian evaporites are not connected to the surface and therefore pressures are not hydrostatic. Connectivity with the surface aquifers is lacking because shale aquitards and impermeable evaporite layers consist of both halite and anhydrite. 5. Developed extensive web applications and an interactive mapping system that do the following: a. Facilitate access to a wide array of data obtained in the study, including core descriptions and analyses, sample logs, digital (LAS) well logs, seismic data, gravity and magnetics maps, structural and stratigraphic maps, inferred fault traces, earthquakes, Class I and II disposal wells, and

The contribution of environmental isotopes to studies of large aquifers in Morocco

International Nuclear Information System (INIS)

Kabbaj, A.; Zeryouhi, I.; Carlier, Ph.

1979-01-01

The geochemistry of environmental isotopes has been used for the study of various aquifers in Morocco, some of which are large, such as the Charf el Akab in the Tangiers area, the Oum er Rbia basin and the Turonian aquifer of the Tadla, the free groundwater of the Quaternary lacustrine limestones of the Sais Plain and the Lias limestone aquifer. These isotope studies take hydrogeochemical data into account and have made it possible to determine the conditions of recharge of the aquifers, to distinguish waters of different origin from the Atlas Mountains or from the Phosphate Plateau in the Tadla Basin and the Sais plain, to estimate the recharge of one aquifer by another - for example groundwater of the Lias limestones passing via the folds of the Sais Plain into the lacustrine limestone aquifer - and to test the homogeneity or heterogeneity of these aquifers and their tightness (e.g. the Turonian aquifer of the Tadla and the special case of the Charf el Akab in relation to the marine environment). Altogether, these results made it possible to test the value of the techniques used and to specify the general conditions in which they can profitably be used. (author)

Elastic Rock Heterogeneity Controls Brittle Rock Failure during Hydraulic Fracturing

Science.gov (United States)

Langenbruch, C.; Shapiro, S. A.

2014-12-01

For interpretation and inversion of microseismic data it is important to understand, which properties of the reservoir rock control the occurrence probability of brittle rock failure and associated seismicity during hydraulic stimulation. This is especially important, when inverting for key properties like permeability and fracture conductivity. Although it became accepted that seismic events are triggered by fluid flow and the resulting perturbation of the stress field in the reservoir rock, the magnitude of stress perturbations, capable of triggering failure in rocks, can be highly variable. The controlling physical mechanism of this variability is still under discussion. We compare the occurrence of microseismic events at the Cotton Valley gas field to elastic rock heterogeneity, obtained from measurements along the treatment wells. The heterogeneity is characterized by scale invariant fluctuations of elastic properties. We observe that the elastic heterogeneity of the rock formation controls the occurrence of brittle failure. In particular, we find that the density of events is increasing with the Brittleness Index (BI) of the rock, which is defined as a combination of Young's modulus and Poisson's ratio. We evaluate the physical meaning of the BI. By applying geomechanical investigations we characterize the influence of fluctuating elastic properties in rocks on the probability of brittle rock failure. Our analysis is based on the computation of stress fluctuations caused by elastic heterogeneity of rocks. We find that elastic rock heterogeneity causes stress fluctuations of significant magnitude. Moreover, the stress changes necessary to open and reactivate fractures in rocks are strongly related to fluctuations of elastic moduli. Our analysis gives a physical explanation to the observed relation between elastic heterogeneity of the rock formation and the occurrence of brittle failure during hydraulic reservoir stimulations. A crucial factor for understanding

Heterogeneity and contaminant transport modeling for the Savannah River integrated demonstration site

International Nuclear Information System (INIS)

Chesnut, D.A.

1992-11-01

The effectiveness of remediating aquifers and vadose zone sediments is frequently controlled by spatial heterogeneities. A continuing and long-recognized problem in selecting, planning, implementing, and operating remediation projects is the development of methods for quantitatively describing heterogeneity and predicting its effects on process performance. The similarity to and differences from modeling oil recovery processes in the petroleum industry are illustrated by the extension to contaminant extraction processes of an analytic model originally developed for waterflooding petroleum reservoirs. The resulting equations incorporate the effects of heterogeneity through a single parameter, σ. Fitting this model to the Savannah River in situ Air Stripping test data suggests that the injection of air into a horizontal well below the water table may have improved performance by changing the flow pattern in the vadose zone. This change increased the capture volume, and consequently the contaminant mass inventory, of the horizontal injection well completed in the vadose zone. The apparent increases (compared to extraction only from the horizontal well) are from 10,200 to 21,000 pounds for TCE and from 3,600 pounds to 59,800 pounds for PCE. The predominance of PCE in this calculated increase suggests that redistribution of flow paths in the vadose zone, rather than in-situ stripping, may provide most of the improvement. Although this preliminary conclusion remains to be reinforced by more sophisticated modeling currently in progress, there appears to be a definite improvement, which is attributable to air injection, over conventional remediation methods

Integrated Reflection Seismic Monitoring and Reservoir Modeling for Geologic CO2 Sequestration

Energy Technology Data Exchange (ETDEWEB)

John Rogers

2011-12-31

The US DOE/NETL CCS MVA program funded a project with Fusion Petroleum Technologies Inc. (now SIGMA) to model the proof of concept of using sparse seismic data in the monitoring of CO{sub 2} injected into saline aquifers. The goal of the project was to develop and demonstrate an active source reflection seismic imaging strategy based on deployment of spatially sparse surface seismic arrays. The primary objective was to test the feasibility of sparse seismic array systems to monitor the CO{sub 2} plume migration injected into deep saline aquifers. The USDOE/RMOTC Teapot Dome (Wyoming) 3D seismic and reservoir data targeting the Crow Mountain formation was used as a realistic proxy to evaluate the feasibility of the proposed methodology. Though the RMOTC field has been well studied, the Crow Mountain as a saline aquifer has not been studied previously as a CO{sub 2} sequestration (storage) candidate reservoir. A full reprocessing of the seismic data from field tapes that included prestack time migration (PSTM) followed by prestack depth migration (PSDM) was performed. A baseline reservoir model was generated from the new imaging results that characterized the faults and horizon surfaces of the Crow Mountain reservoir. The 3D interpretation was integrated with the petrophysical data from available wells and incorporated into a geocellular model. The reservoir structure used in the geocellular model was developed using advanced inversion technologies including Fusion's ThinMAN{trademark} broadband spectral inversion. Seal failure risk was assessed using Fusion's proprietary GEOPRESS{trademark} pore pressure and fracture pressure prediction technology. CO{sub 2} injection was simulated into the Crow Mountain with a commercial reservoir simulator. Approximately 1.2MM tons of CO{sub 2} was simulated to be injected into the Crow Mountain reservoir over 30 years and subsequently let 'soak' in the reservoir for 970 years. The relatively small plume

An Integrated Approach to Characterizing Bypassed Oil in Heterogeneous and Fractured Reservoirs Using Partitioning Tracers. Annual Report

International Nuclear Information System (INIS)

Akhil Datta-Gupta

2006-01-01

This report presents an efficient trajectory-based approach to integrate transient pressure data into high-resolution reservoir and aquifer models. The method involves alternating travel time and peak amplitude matching of pressure response using inverse modeling and is particularly well-suited for high resolution subsurface characterization using hydraulic tomography or pressure interference tests. Compared to travel time inversion only, our proposed approach results in a significantly improved match of the pressure response at the wells and also better estimates of subsurface properties. This is accomplished with very little increase in computational cost. Utilizing the concept of a ''diffusive'' time of flight derived from an asymptotic solution of the diffusivity equation, we develop analytical approaches to estimate the sensitivities for travel time and peak amplitude of pressure response to subsurface properties. The sensitivities are then used in an iterative least-squared minimization to match the pressure data. We illustrate our approach using synthetic and field examples. In the field application at a fractured limestone formation, the predominant fracture patterns emerging from the inversion are shown to be consistent with independent geophysical experiments and borehole data

Water resources of Rockland County, New York, 2005-07, with emphasis on the Newark Basin Bedrock Aquifer

Science.gov (United States)

Heisig, Paul M.

2011-01-01

Concerns over the state of water resources in Rockland County, NY, prompted an assessment of current (2005-07) conditions. The investigation included a review of all water resources but centered on the Newark basin aquifer, a fractured-bedrock aquifer over which nearly 300,000 people reside. Most concern has been focused on this aquifer because of (1) high summer pumping rates, with occasional entrained-air problems and an unexplained water-level decline at a monitoring well, (2) annual withdrawals that have approached or even exceeded previous estimates of aquifer recharge, and (3) numerous contamination problems that have caused temporary or long-term shutdown of production wells. Public water supply in Rockland County uses three sources of water in roughly equal parts: (1) the Newark basin sedimentary bedrock aquifer, (2) alluvial aquifers along the Ramapo and Mahwah Rivers, and (3) surface waters from Lake DeForest Reservoir and a smaller, new reservoir supply in the Highlands part of the county. Water withdrawals from the alluvial aquifer in the Ramapo River valley and the Lake DeForest Reservoir are subject to water-supply application permits that stipulate minimum flows that must be maintained downstream into New Jersey. There is a need, therefore, at a minimum, to prevent any loss of the bedrock-aquifer resource--to maintain it in terms of both sustainable use and water-quality protection. The framework of the Newark basin bedrock aquifer included characterization of (1) the structure and fracture occurrence associated with the Newark basin strata, (2) the texture and thickness of overlying glacial and alluvial deposits, (3) the presence of the Palisades sill and associated basaltic units on or within the Newark basin strata, and (4) the streams that drain the aquifer system. The greatest concern regarding sustainability of groundwater resources is the aquifer response to the seasonal increase in pumping rates from May through October (an average increase

Aquifer Characteristics Data Report for the Weldon Spring Site chemical plant/raffinate pits and vicinity properties for the Weldon Spring Site Remedial Action Project, Weldon Spring, Missouri

International Nuclear Information System (INIS)

1990-11-01

This report describes the procedures and methods used, and presents the results of physical testing performed, to characterize the hydraulic properties of the shallow Mississippian-Devonian aquifer beneath the Weldon Spring chemical plant, raffinate pits, and vicinity properties. The aquifer of concern is composed of saturated rocks of the Burlington-Keokuk Limestone which constitutes the upper portion of the Mississippian-Devonian aquifer. This aquifer is a heterogeneous anisotropic medium which can be described in terms of diffuse Darcian flow overlain by high porosity discrete flow zones and conduits. Average hydraulic conductivity for all wells tested is 9.6E-02 meters/day (3.1E-01 feet/day). High hydraulic conductivity values are representative of discrete flow in the fractured and weathered zones in the upper Burlington-Keokuk Limestone. They indicate heterogeneities within the Mississippian-Devonian aquifer. Aquifer heterogeneity in the horizontal plane is believed to be randomly distributed and is a function of fracture spacing, solution voids, and preglacial weathering phenomena. Relatively high hydraulic conductivities in deeper portions of the aquifer are though to be due to the presence of widely spaced fractures. 44 refs., 27 figs., 9 tabs

Demonstrating storage of CO2 in geological reservoirs: the Sleipner and SACS projects

International Nuclear Information System (INIS)

Torp, T.A.; Gale, J.

2004-01-01

At the Sleipner gas field in the North Sea, CO 2 has been stripped from the produced natural gas and injected into a sand layer called the Utsira formation. Injection started in October 1996, to date nearly 8 million tonnes of CO 2 have been injected without any significant operational problems observed in the capture plant or in the injection well. The Sleipner project is the first commercial application of CO 2 storage in deep saline aquifers in the world. To monitor the injected CO 2 , a separate project called the saline aquifer CO 0 2 storage (SACS) project was established in 1998. As part of the SACS project, 3D seismic surveying has been used to successfully monitor the CO 2 in the Utsira formation, an industry first. Repeat seismic surveys have successfully imaged movement of the injected CO 2 within the reservoir. Reservoir simulation tools have been successfully adapted to describe the migration of the CO 2 in the reservoir. The simulation packages have been calibrated against the repeat seismic surveys and shown themselves to be capable of replicating the position of the CO 2 in the reservoir. The possible reactions between minerals within the reservoir sand and the injected CO 2 have been studied by laboratory experiments and simulations. The cumulative experiences of the Sleipner and SACS projects will be embodied in a Best Practice Manual to assist other organisations planning CO 2 injection projects to take advantage of the learning processes undertaken and to assist in facilitating new projects of this type. (author)

IMPROVING CO2 EFFICIENCY FOR RECOVERING OIL IN HETEROGENEOUS RESERVOIRS

Energy Technology Data Exchange (ETDEWEB)

Reid B. Grigg; Robert K. Svec; Zhengwen Zeng; Baojun Bai; Yi Liu

2004-09-27

The third annual report of ''Improving CO{sub 2} Efficiency for Recovery Oil in Heterogeneous Reservoirs'' presents results of laboratory studies with related analytical models for improved oil recovery. All studies were designed to optimize utilization and extend the practice of CO{sub 2} flooding to a wider range of reservoirs. Chapter 1 describes the behavior at low concentrations of the surfactant Chaser International CD1045{trademark} (CD) versus different salinity, pressure and temperature. Results of studies on the effects of pH and polymer (hydrolyzed polyacrylamide?HPAM) and CO{sub 2} foam stability after adsorption in the core are also reported. Calcium lignosulfonate (CLS) transport mechanisms through sandstone, description of the adsorption of CD and CD/CLS onto three porous media (sandstone, limestone and dolomite) and five minerals, and the effect of adsorption on foam stability are also reported. In Chapter 2, the adsorption kinetics of CLS in porous Berea sandstone and non-porous minerals are compared by monitoring adsorption density change with time. Results show that adsorption requires a much longer time for the porous versus non-porous medium. CLS adsorption onto sandstone can be divided into three regions: adsorption controlled by dispersion, adsorption controlled by diffusion and adsorption equilibrium. NaI tracer used to characterize the sandstone had similar trends to earlier results for the CLS desorption process, suggesting a dual porosity model to simulate flow through Berea sandstone. The kinetics and equilibrium test for CD adsorption onto five non-porous minerals and three porous media are reported in Chapter 3. CD adsorption and desorption onto non-porous minerals can be established in less than one hour with adsorption densities ranging from 0.4 to 1.2 mg of CD per g of mineral in decreasing order of montmorillonite, dolomite, kaolinite, silica and calcite. The surfactant adsorption onto three porous media takes

Direct Breakthrough Curve Prediction From Statistics of Heterogeneous Conductivity Fields

Science.gov (United States)

Hansen, Scott K.; Haslauer, Claus P.; Cirpka, Olaf A.; Vesselinov, Velimir V.

2018-01-01

This paper presents a methodology to predict the shape of solute breakthrough curves in heterogeneous aquifers at early times and/or under high degrees of heterogeneity, both cases in which the classical macrodispersion theory may not be applicable. The methodology relies on the observation that breakthrough curves in heterogeneous media are generally well described by lognormal distributions, and mean breakthrough times can be predicted analytically. The log-variance of solute arrival is thus sufficient to completely specify the breakthrough curves, and this is calibrated as a function of aquifer heterogeneity and dimensionless distance from a source plane by means of Monte Carlo analysis and statistical regression. Using the ensemble of simulated groundwater flow and solute transport realizations employed to calibrate the predictive regression, reliability estimates for the prediction are also developed. Additional theoretical contributions include heuristics for the time until an effective macrodispersion coefficient becomes applicable, and also an expression for its magnitude that applies in highly heterogeneous systems. It is seen that the results here represent a way to derive continuous time random walk transition distributions from physical considerations rather than from empirical field calibration.

Information content of slug tests for estimating hydraulic properties in realistic, high-conductivity aquifer scenarios

Science.gov (United States)

Cardiff, Michael; Barrash, Warren; Thoma, Michael; Malama, Bwalya

2011-06-01

heterogeneous, highly conductive aquifer, we present some general findings that have applicability to slug testing. In particular, we find that aquifer hydraulic conductivity estimates obtained from larger slug heights tend to be lower on average (presumably due to non-linear wellbore losses) and tend to be less variable (presumably due to averaging over larger support volumes), supporting the notion that using the smallest slug heights possible to produce measurable water level changes is an important strategy when mapping aquifer heterogeneity. Finally, we present results specific to characterization of the aquifer at the Boise Hydrogeophysical Research Site. Specifically, we note that (1) K estimates obtained using a range of different slug heights give similar results, generally within ±20%; (2) correlations between estimated K profiles with depth at closely-spaced wells suggest that K values obtained from slug tests are representative of actual aquifer heterogeneity and not overly affected by near-well media disturbance (i.e., "skin"); (3) geostatistical analysis of K values obtained indicates reasonable correlation lengths for sediments of this type; and (4) overall, K values obtained do not appear to correlate well with porosity data from previous studies.

Integration of dynamical data in a geostatistical model of reservoir; Integration des donnees dynamiques dans un modele geostatistique de reservoir

Energy Technology Data Exchange (ETDEWEB)

Costa Reis, L.

2001-01-01

We have developed in this thesis a methodology of integrated characterization of heterogeneous reservoirs, from geologic modeling to history matching. This methodology is applied to the reservoir PBR, situated in Campos Basin, offshore Brazil, which has been producing since June 1979. This work is an extension of two other thesis concerning geologic and geostatistical modeling of the reservoir PBR from well data and seismic information. We extended the geostatistical litho-type model to the whole reservoir by using a particular approach of the non-stationary truncated Gaussian simulation method. This approach facilitated the application of the gradual deformation method to history matching. The main stages of the methodology for dynamic data integration in a geostatistical reservoir model are presented. We constructed a reservoir model and the initial difficulties in the history matching led us to modify some choices in the geological, geostatistical and flow models. These difficulties show the importance of dynamic data integration in reservoir modeling. The petrophysical property assignment within the litho-types was done by using well test data. We used an inversion procedure to evaluate the petrophysical parameters of the litho-types. The up-scaling is a necessary stage to reduce the flow simulation time. We compared several up-scaling methods and we show that the passage from the fine geostatistical model to the coarse flow model should be done very carefully. The choice of the fitting parameter depends on the objective of the study. In the case of the reservoir PBR, where water is injected in order to improve the oil recovery, the water rate of the producing wells is directly related to the reservoir heterogeneity. Thus, the water rate was chosen as the fitting parameter. We obtained significant improvements in the history matching of the reservoir PBR. First, by using a method we have proposed, called patchwork. This method allows us to built a coherent

Pennsylvanian carbonate buildups, Paradox basin: Increasing reserves in heterogeneous, shallow-shelf reservoirs

Science.gov (United States)

Montgomery, S.L.; Chidsey, T.C.; Eby, D.E.; Lorenz, D.M.; Culham, W.E.

1999-01-01

Productive carbonate buildups of Pennsylvanian age in the southern Paradox basin, Utah, contain up to 200 million bbl remaining oil potentially recoverable by enhanced recovery methods. These buildups comprise over 100 satellite fields to the giant Greater Aneth field, where secondary recovery operations thus far have been concentrated. Several types of satellite buildups exist and produce oil from the Desert Creek zone of the Paradox Formation. Many of the relevant fields have undergone early abandonment; wells in Desert Creek carbonate mounds commonly produce at very high initial rates (>1000 bbl/day) and then suffer precipitous declines. An important new study focused on the detailed characterization of five separate reservoirs has resulted in significant information relevant to their future redevelopment. Completed assessment of Anasazi field suggests that phylloid algal mounds, the major productive buildup type in this area, consist of ten separate lithotypes and can be described in terms of a two-level reservoir system with an underlying high-permeability mound-core interval overlain by a lower permeability but volumetrically larger supramound (mound capping) interval. Reservoir simulations and related performance predictions indicate that CO2 flooding of these reservoirs should have considerable success in recovering remaining oil reserves.Productive carbonate buildups of Pennsylvanian age in the southern Paradox basin, Utah, contain up to 200 million bbl remaining oil potentially recoverable by enhanced recovery methods. These buildups comprise over 100 satellite fields to the giant Greater Aneth field, where secondary recovery operations thus far have been concentrated. Several types of satellite buildups exist and produce oil from the Desert Creek zone of the Paradox Formation. Many of the relevant fields have undergone early abandonment; wells in Desert Creek carbonate mounds commonly produce at very high initial rates (>1000 bbl/day) and then suffer

Thermophysical behavior of St. Peter sandstone: application to compressed air energy storage in an aquifer

Energy Technology Data Exchange (ETDEWEB)

Erikson, R.L.

1983-12-01

The long-term stability of a sandstone reservoir is of primary importance to the success of compressed air energy storage (CAES) in aquifers. The purpose of this study was to: develop experimental techniques for the operation of the CAES Porous Media Flow Loop (PMFL), an apparatus designed to study the stability of porous media in subsurface geologic environments, conduct experiments in the PMFL designed to determine the effects of temperature, stress, and humidity on the stability of candidate CAES reservoir materials, provide support for the CAES field demonstration project in Pittsfield, Illinois, by characterizing the thermophysical stability of Pittsfield reservoir sandstone under simulated field conditions.

Characterization of aquifer heterogeneity in a complex fluvial hydrogeologic system to evaluate migration in ground water

International Nuclear Information System (INIS)

Baker, F.G.; Pavlik, H.F.

1990-01-01

The hydrogeology and extent of ground water contamination were characterized at a site in northern California. Wood preserving compounds, primarily pentachlorophenol (PCP) and creosote, have been detected in the soil and ground water. A plume of dissolved PCP up to 1.5 miles long has been identified south of the plant. The aquifer consists of a complex multizonal system of permeable gravels and sands composed of units from four geologic formations deposited by the ancestral Feather River. Fluvial channel gravels form the principal aquifer zones and contain overbank clay and silt deposits which locally form clay lenses or more continuous aquitards. The geometric mean horizontal hydraulic conductivities for channel gravels range between 120 to 530 feet/day. Mean vertical aquitard hydraulic conductivity is 0.07 feet/day. Ground water flow is generally southward with a velocity ranging from 470 to 1000 feet/year. The spatial distribution of dissolved PCP in the aquifer documents the interactions between major permeable zones. Hydrostratigraphic evidence pointing to the separation of aquifer zones is supported by the major ion chemistry of ground water. The sodium and calcium-magnesium bicarbonate-rich water present in the upper aquifer zones is significantly different in chemical composition from the predominantly sodium chloride-rich water present in the deeper permeable zone. This indicates that hydrodynamic separation exists between the upper and lower zones of the aquifer, limiting the vertical movement of the PCP plume. A numerical ground water model, based on this conceptual hydrogeologic model, was developed to evaluate groundwater transport pathways and for use in the design of a ground water extraction and treatment system. (9 refs., 7 figs., tab.)

Analysis of Tide and Offshore Storm-Induced Water Table Fluctuations for Structural Characterization of a Coastal Island Aquifer

Science.gov (United States)

Trglavcnik, Victoria; Morrow, Dean; Weber, Kela P.; Li, Ling; Robinson, Clare E.

2018-04-01

Analysis of water table fluctuations can provide important insight into the hydraulic properties and structure of a coastal aquifer system including the connectivity between the aquifer and ocean. This study presents an improved approach for characterizing a permeable heterogeneous coastal aquifer system through analysis of the propagation of the tidal signal, as well as offshore storm pulse signals through a coastal aquifer. Offshore storms produce high wave activity, but are not necessarily linked to significant onshore precipitation. In this study, we focused on offshore storm events during which no onshore precipitation occurred. Extensive groundwater level data collected on a sand barrier island (Sable Island, NS, Canada) show nonuniform discontinuous propagation of the tide and offshore storm pulse signals through the aquifer with isolated inland areas showing enhanced response to both oceanic forcing signals. Propagation analysis suggests that isolated inland water table fluctuations may be caused by localized leakage from a confined aquifer that is connected to the ocean offshore but within the wave setup zone. Two-dimensional groundwater flow simulations were conducted to test the leaky confined-unconfined aquifer conceptualization and to identify the effect of key parameters on tidal signal propagation in leaky confined-unconfined coastal aquifers. This study illustrates that analysis of offshore storm signal propagation, in addition to tidal signal propagation, provides a valuable and low resource approach for large-scale characterization of permeable heterogeneous coastal aquifers. Such an approach is needed for the effective management of coastal environments where water resources are threatened by human activities and the changing climate.

Transport of the reactive substances eosin, uranium and lithium in a heterogeneous aquifer; Transport der reaktiven Stoffe Eosin, Uranin und Lithium in einem heterogenen Grundwasserleiter

Energy Technology Data Exchange (ETDEWEB)

Doering, U.

1997-02-01

To predict the movement of a contaminant plume in an aquifer is still a task of great uncertainty. This uncertainty is generally attributed to an insufficient understanding of the chemical reaction processes and/or to the natural aquifer heterogeneities. In an integrated approach of field experiments, laboratory experiments and numerical simulations, the transport of the weakly reactive solutes eosin, uranin and lithium was investigated at a test site near the Research Center in Juelich. The field scale transport behavior of the solutes was studied by large scale tracer tests. To characterize aquifer heterogeneities, in-situ and laboratory measurements were performed. In-situ measurements covered about 1500 flowmeter measurements and 90 determinations of the groundwater flow velocity by the borehole method. The spatial variability of hydraulic and physico-chemical parameters was further determined on 400 sediment samples. These parameters included: Grain size distribution, calculated hydraulic conductivity, unconformity and as physico-chemical parameters the organic carbon content, specific surface and the cation exchange capacity. Furthermore sorption coefficients were measured on 75 sediment samples for uranium and lithium. The statistical evaluation of these data showed that the hydraulic heterogeneity was larger but in the same order of magnitude as the physico-chemical parameters. (orig./SR) [Deutsch] Eine Schadstoff-Ausbreitung im Grundwasser vorherzusagen, ist noch immer eine Aufgabe mit unsicherem Ergebnis. Diese Prognose-Unsicherheiten werden im Allgemeinen auf ein unzureichendes Verstaendnis der chemischen Reaktionsprozesse und/oder auf die natuerliche Heterogenitaet des Grundwasserleiters zurueckgefuehrt. In dem hier beschriebenen Forschungsprojekt, das Feldversuche, Laborversuche und numerische Simulationen integriert, wurde der Transport der schwach reaktiven Substanzen Eosin, Uranin und Lithium auf einem Versuchsgelaende nahe des Forschungszentrums

Using the nonlinear aquifer storage–discharge relationship to simulate the base flow of glacier- and snowmelt-dominated basins in northwest China

Directory of Open Access Journals (Sweden)

R. Gan

2013-09-01

Full Text Available Base flow is an important component in hydrological modeling. This process is usually modeled by using the linear aquifer storage–discharge relation approach, although the outflow from groundwater aquifers is nonlinear. To identify the accuracy of base flow estimates in rivers dominated by snowmelt and/or glacier melt in arid and cold northwestern China, a nonlinear storage–discharge relationship for use in SWAT (Soil Water Assessment Tool modeling was developed and applied to the Manas River basin in the Tian Shan Mountains. Linear reservoir models and a digital filter program were used for comparisons. Meanwhile, numerical analysis of recession curves from 78 river gauge stations revealed variation in the parameters of the nonlinear relationship. It was found that the nonlinear reservoir model can improve the streamflow simulation, especially for low-flow period. The higher Nash–Sutcliffe efficiency, logarithmic efficiency, and volumetric efficiency, and lower percent bias were obtained when compared to the one-linear reservoir approach. The parameter b of the aquifer storage–discharge function varied mostly between 0.0 and 0.1, which is much smaller than the suggested value of 0.5. The coefficient a of the function is related to catchment properties, primarily the basin and glacier areas.

Using the nonlinear aquifer storage-discharge relationship to simulate the base flow of glacier- and snowmelt-dominated basins in northwest China

Science.gov (United States)

Gan, R.; Luo, Y.

2013-09-01

Base flow is an important component in hydrological modeling. This process is usually modeled by using the linear aquifer storage-discharge relation approach, although the outflow from groundwater aquifers is nonlinear. To identify the accuracy of base flow estimates in rivers dominated by snowmelt and/or glacier melt in arid and cold northwestern China, a nonlinear storage-discharge relationship for use in SWAT (Soil Water Assessment Tool) modeling was developed and applied to the Manas River basin in the Tian Shan Mountains. Linear reservoir models and a digital filter program were used for comparisons. Meanwhile, numerical analysis of recession curves from 78 river gauge stations revealed variation in the parameters of the nonlinear relationship. It was found that the nonlinear reservoir model can improve the streamflow simulation, especially for low-flow period. The higher Nash-Sutcliffe efficiency, logarithmic efficiency, and volumetric efficiency, and lower percent bias were obtained when compared to the one-linear reservoir approach. The parameter b of the aquifer storage-discharge function varied mostly between 0.0 and 0.1, which is much smaller than the suggested value of 0.5. The coefficient a of the function is related to catchment properties, primarily the basin and glacier areas.

Aquifer test to determine hydraulic properties of the Elm aquifer near Aberdeen, South Dakota

Science.gov (United States)

Schaap, Bryan D.

2000-01-01

SOLVE, Inc. These best fit theoretical response curves are based on a transmissivity of 24,000 ft2/d or a hydraulic conductivity of about 600 ft/d, a storage coefficient of 0.05, a specific yield of 0.42, and vertical hydraulic conductivity equal to horizontal hydraulic conductivity. The theoretical type curves match the observed data fairly closely at Wells A and B until about 2,500 minutes and 1,000 minutes, respectively, after pumping began. The increasing rate of drawdown after these breaks is an indication that a no-flow boundary (an area with much lower hydraulic conductivity) likely was encountered and that Wells A and B may be completed in a part of the Elm aquifer with limited hydraulic connection to the rest of the aquifer. Additional analysis indicates that if different assumptions regarding the screened interval for Well B and aquifer anisotropy are used, type curves can be calculated that fit the observed data using a lower specific yield that is within the commonly accepted range. When the screened interval for Well B was reduced to 5 ft near the top of the aquifer and horizontal hydraulic conductivity was set to 20 times vertical hydraulic conductivity, the type curves calculated using a specific yield of 0.1 and a transmissivity of 30,200 ft2/d also matched the observed data from Wells A and B fairly well. A version of the Theim equilibrium equation was used to calculate the theoretical drawdown in an idealized unconfined aquifer when a perfectly efficient well is being pumped at a constant rate. These calculations were performed for a range of pumping rates, drawdowns at the wells, and distances between wells that might be found in a production well field in the Elm aquifer. Although the aquifer test indicates that hydraulic conductivity near the well may be adequate to support a production well, the comparison of drawdown and recovery curves indicates the possibility that heterogeneities may limit the productive capacity of specific loca

How secure is subsurface CO2 storage? Controls on leakage in natural CO2 reservoirs

Science.gov (United States)

Miocic, Johannes; Gilfillan, Stuart; McDermott, Christopher; Haszeldine, Stuart

2014-05-01

Carbon Capture and Storage (CCS) is the only industrial scale technology available to directly reduce carbon dioxide (CO2) emissions from fossil fuelled power plants and large industrial point sources to the atmosphere. The technology includes the capture of CO2 at the source and transport to subsurface storage sites, such as depleted hydrocarbon reservoirs or saline aquifers, where it is injected and stored for long periods of time. To have an impact on the greenhouse gas emissions it is crucial that there is no or only a very low amount of leakage of CO2 from the storage sites to shallow aquifers or the surface. CO2 occurs naturally in reservoirs in the subsurface and has often been stored for millions of years without any leakage incidents. However, in some cases CO2 migrates from the reservoir to the surface. Both leaking and non-leaking natural CO2 reservoirs offer insights into the long-term behaviour of CO2 in the subsurface and on the mechanisms that lead to either leakage or retention of CO2. Here we present the results of a study on leakage mechanisms of natural CO2 reservoirs worldwide. We compiled a global dataset of 49 well described natural CO2 reservoirs of which six are leaking CO2 to the surface, 40 retain CO2 in the subsurface and for three reservoirs the evidence is inconclusive. Likelihood of leakage of CO2 from a reservoir to the surface is governed by the state of CO2 (supercritical vs. gaseous) and the pressure in the reservoir and the direct overburden. Reservoirs with gaseous CO2 is more prone to leak CO2 than reservoirs with dense supercritical CO2. If the reservoir pressure is close to or higher than the least principal stress leakage is likely to occur while reservoirs with pressures close to hydrostatic pressure and below 1200 m depth do not leak. Additionally, a positive pressure gradient from the reservoir into the caprock averts leakage of CO2 into the caprock. Leakage of CO2 occurs in all cases along a fault zone, indicating that

Hydrogeological geochemical and isotopic study of the coastal aquifer of Sousse Eastern, Tunisia

International Nuclear Information System (INIS)

Ben-Hamouda, M. F.; Carreira, P.; Marques, J. M.; Eggenkamp, H.

2012-12-01

At Sahel, near one of the seaside resort available in Tunisia, the water quantity and quality is a major problem ever at southern center of Tunisia. The Oued Laya coastal system is no exception. The levels, a shallow aquifer up to depths of about 60 m whose reservoir is mainly formed by Mio-Pliocnesediments (with some gypsum lenses dispersed within the geological formations) and deep aquifer, situated between 100 and 250 m depth, located in the Miocene sandstone formations. The results of geochemical and isotopic studies have shown that groundwater salinity seems not be linked with the increasing water well's abstraction. In contrast, water mineralization seems to acquired by dissolution of minerals in the aquifer system especially halie and gypsum. Besides ion exchange processes play also an important role in the groundwater mineralization. Therefore, it clearly appears that several sources might contribute with different mineralization to the selenization of the aquifer through the natural recharge and also through the return of water irrigation. The contamination of the Mio-Pliocene shallow aquifer by a mixture with seawater is confirmed, and stable isotopes data do not support the hypothesis of mixing with seawater. (Author)

Hydrochemical processes in a shallow coal seam gas aquifer and its overlying stream–alluvial system: implications for recharge and inter-aquifer connectivity

International Nuclear Information System (INIS)

Duvert, Clément; Raiber, Matthias; Owen, Daniel D.R.; Cendón, Dioni I.; Batiot-Guilhe, Christelle; Cox, Malcolm E.

2015-01-01

Highlights: • Major ions and isotopes used to study inter-aquifer mixing in a shallow CSG setting. • Considerable heterogeneity in the water composition of the coal-bearing aquifer. • Rapid recharge of the coal-bearing aquifer through highly fractured igneous rocks. • Potential mixing between the coal-bearing aquifer and downstream alluvial aquifer. • Need to consider the seasonal influences on inter-aquifer mixing in CSG settings. - Abstract: In areas of potential coal seam gas (CSG) development, understanding interactions between coal-bearing strata and adjacent aquifers and streams is of highest importance, particularly where CSG formations occur at shallow depth. This study tests a combination of hydrochemical and isotopic tracers to investigate the transient nature of hydrochemical processes, inter-aquifer mixing and recharge in a catchment where the coal-bearing aquifer is in direct contact with the alluvial aquifer and surface drainage network. A strong connection was observed between the main stream and underlying alluvium, marked by a similar evolution from fresh Ca–Mg–HCO 3 waters in the headwaters towards brackish Ca–Na–Cl composition near the outlet of the catchment, driven by evaporation and transpiration. In the coal-bearing aquifer, by contrast, considerable site-to-site variations were observed, although waters generally had a Na–HCO 3 –Cl facies and high residual alkalinity values. Increased salinity was controlled by several coexisting processes, including transpiration by plants, mineral weathering and possibly degradation of coal organic matter. Longer residence times and relatively enriched carbon isotopic signatures of the downstream alluvial waters were suggestive of potential interactions with the shallow coal-bearing aquifer. The examination of temporal variations in deuterium excess enabled detection of rapid recharge of the coal-bearing aquifer through highly fractured igneous rocks, particularly at the catchment

The Role of Horizontal Wells when Developing Low-Permeable, Heterogeneous Reservoirs

Directory of Open Access Journals (Sweden)

M.P. Yurova

2017-09-01

Full Text Available The widespread use of horizontal drilling in recent years has shown that horizontal wells can be successfully used both at the initial and late stages of development. This is due to the fact that horizontal wells, in contrast to vertical wells, contact a larger area of ​​the productive formation, while the surface of drainage of the oil-saturated layer, productivity of the wells due to the formation of cracks, and also the influence on thin layers increases. One of the methods of impact on the reservoir is the steam-thermal method. The main advantage of the use of the heat wave method in horizontal wells is a significant increase in the well production rate, a decrease in the water cut of the reservoir, a decrease in the oil viscosity, an increase in the injectivity of the injection well, and an increase in the inflow in producing wells. As a result of the total effect, a significant increase in production is obtained throughout the entire deposit. Enhanced oil recovery from the injection of steam is achieved by reducing the viscosity of oil, covering the reservoir with steam, distilling oil and extracting with a solvent. All this increases the displacement coefficient. One of the most effective ways to increase oil recovery at a late stage of field operation is sidetracking in emergency, highly watered and low-productive wells. This leads to the development of residual reserves in weakly drained zones of reservoirs with a substantial increase in well productivity in low-permeable reservoirs. This approach assumes that the initial drilling of wells is a ‘pilot’ stage, which precedes the development of oil reserves in the late stages of deposit development. In the fields of Western Siberia, multiple hydraulic fracturing of the reservoir has been improved due to a special stinger in the liner hanger of multi-packer installation, which excludes the influence of high pressures on the production column under the multiple hydraulic fracturing

Interprétation hydrogéologique de l'aquifère des bassins sud-rifains (Maroc) : apport de la sismique réflexionHydrogeological interpretation of the southern Rifean basins aquifer (Morocco): seismic reflexion contribution

Science.gov (United States)

Zouhri, Lahcen; Gorini, Christian; Lamouroux, Christian; Vachard, Daniel; Dakki, Mohammed

2003-03-01

The aquifer of the Rharb Basin is constituted by heterogeneous material. The seismic reflexion interpretation carried out in this area, highlighted a permeable device compartmentalized in raised and subsided blocks. Depressions identified in the northern and southernmost zones are characterized by Plio-Quaternary fillings that are favourable to the hydrogeological exploitation. Two mechanisms contribute to structure the Plio-Quaternary aquifer: the Hercynian reactivation in the southernmost part, and the gravitational mechanism of the Pre-Rifean nappe. The groundwater flow and the aquifer thickening are controlled by this reactivation.

MRF-based Stochastic Joint Inversion of Hydrological and Geophysical Datasets to Evaluate Aquifer Heterogeneities.

Science.gov (United States)

Oware, E. K.

2016-12-01

Hydrogeophysical assessment of aquifer parameters typically involve sparse noisy measurements coupled with incomplete understanding of the underlying physical process. Thus, recovering a single deterministic solution in light of the largely uncertain inputs is unrealistic. Stochastic imaging (SI) allows the retrieval of multiple equiprobable outcomes that facilitate probabilistic assessment of aquifer properties in a realistic fashion. Representation of prior models is a key aspect of the formulation of SI frameworks. However, higher-order (HO) statistics for representing complex priors in SI are usually borrowed from training images (TIs), which may bias outcomes if the prior hypotheses are inaccurate. A data-driven HO simulation alternative based on Markov random field (MRF) modeling is presented. Here, the modeling of spatial features is guided by potential (Gibbs) energy (PE) minimization. The estimation of the PE encompasses local neighborhood configuration (LNC) and prior statistical constraints. The lower the estimated PE the higher the likelihood of that particular local structure and vice versa. Hence, the LNC component of the PE estimation is designed to promote the recovery of some desired structures while penalizing the retrieval of patterns that are inconsistent with prior expectation. The statistical structure is adaptively inferred from the joint conditional datasets. The reconstruction proceeds in two-steps with the estimation of the lithological structure of the aquifer followed by the simulation of attributes within the identified lithologies. This two-step approach permits the delineation of physically realistic crisp lithological boundaries. The algorithm is demonstrated with a joint inversion of time-lapse concentration and electrical resistivity measurements, in a hypothetical trinary hydrofacies aquifer characterization problem.

The aquifer recharge: an overview of the legislative and planning aspect.

Science.gov (United States)

De Giglio, O; Caggiano, G; Apollonio, F; Marzella, A; Brigida, S; Ranieri, E; Lucentini, L; Uricchio, V F; Montagna, M T

2018-01-01

In most regions of the world, safeguarding groundwater resources is a serious issue, particularly in coastal areas where groundwater is the main water source for drinking, irrigation and industry. Water availability depends on climate, topography and geology. The aim of this paper is to evaluate aquifer recharge as a possible strategy to relieve water resource scarcity. Natural aquifer recharge is defined as the downward flow of water reaching the water table, increasing the groundwater reservoir. Hydro-meteorological factors (rainfall, evapotranspiration and runoff) may alter natural recharge processes. Artificial aquifer recharge is a process by which surface water is introduced with artificial systems underground to fill an aquifer. As a consequence of global warming that has increased the frequency and severity of natural disasters like the drought, the impacts of climate change and seasonality, the artificial recharge has been considered as a viable option. Different direct and indirect techniques can be used, and the choice depends on the hydrologic characteristics of a specific area. In Italy, Legislative Decree no. 152/06 plans artificial aquifer recharge as an additional measure in water management, and Decree no. 100/2016 establishes quantitative and qualitative conditions for recharge. Many projects examine aquifer recharge, such us WADIS-MAR in the southern Mediterranean region, WARBO in Italy and municipal wastewater treatment project in Apulia, a southern Italian region. However, aside from groundwater recharge, the community must foster a spirit of cooperation to manage groundwater as a sustainable resource.

Use of ``rock-typing`` to characterize carbonate reservoir heterogeneity. Final report

Energy Technology Data Exchange (ETDEWEB)

Ikwuakor, K.C.

1994-03-01

The objective of the project was to apply techniques of ``rock-typing`` and quantitative formation evaluation to borehole measurements in order to identify reservoir and non-reservoir rock-types and their properties within the ``C`` zone of the Ordovician Red River carbonates in the northeast Montana and northwest North Dakota areas of the Williston Basin. Rock-typing discriminates rock units according to their pore-size distribution. Formation evaluation estimates porosities and pore fluid saturation. Rock-types were discriminated using crossplots involving three rock-typing criteria: (1) linear relationship between bulk density and porosity, (2) linear relationship between acoustic interval transit-time and porosity, and (3) linear relationship between acoustic interval transit-time and bulk density. Each rock-type was quantitatively characterized by the slopes and intercepts established for different crossplots involving the above variables, as well as porosities and fluid saturations associated with the rock-types. All the existing production was confirmed through quantitative formation evaluation. Highly porous dolomites and anhydritic dolomites contribute most of the production, and constitute the best reservoir rock-types. The results of this study can be applied in field development and in-fill drilling. Potential targets would be areas of porosity pinchouts and those areas where highly porous zones are downdip from non-porous and tight dolomites. Such areas are abundant. In order to model reservoirs for enhanced oil recovery (EOR) operations, a more localized (e.g. field scale) study, expanded to involve other rock-typing criteria, is necessary.

Contribution to the hydrogeological, geochemical and isotopic study of Ain El Beidha and Merguellil (Kairouan plain) aquifers: Implication for the dam-aquifer relationship

International Nuclear Information System (INIS)

Ben Ammar, Safouan

2007-01-01

karst before reaching the Kairouan plain aquifer (springs). Groundwater under flow is estimated at 9 M m3 year-1 and the karstic spring flow is evaluated at 10 M m3 year-1. The spring waters show an intermediate isotope composition between dam reservoir water and the upper catchment of Ain el Beidha basin. The contribution of dam water in mixed water (spring) varies between 21 to 66% depending on time. Values from 18O and 2H ratio are well correlated with the karstic spring flow and with the water level in the reservoir. The hydrogeological study helped to understand the hydrodynamic functioning of the Kairouan plain aquifer system and identified a decline of the water table levels (1.5 m year-1). This decrease is explained mainly by over exploitation (4.8 M m3 year-1). The hydrochemical investigation indicated that the rock-water interaction is the main process contributing to the groundwater salinization. All the samples collected in the Merguellil basin are of the main hydrochemical type: Cl-SO4-Na. Stable isotope values measured in the upstream part of plain, closer the dam, differ from other parts of the aquifer, therefore suggesting a significant input from evaporated dam waters mixed with Ain el Beidha groundwater (spring water coming from the karst). This contamination can be observed as far as 7 km downstream. However, isotopic imprint of the previous recharge process (infiltration of wadi floods) are still noticeable. The residence time of the groundwater was estimated by carbon-14 dating that shows variable values of transit velocity of the groundwater ranging from 3.36 to 0.44 m year-1 depending on the groundwater flow and on the lithological variability of the aquifer. (Author).

Risk Assessment of Carbon Sequestration into A Naturally Fractured Reservoir at Kevin Dome, Montana

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Minh [Univ. of Wyoming, Laramie, WY (United States); Onishi, Tsubasa [Texas A & M Univ., College Station, TX (United States); Carey, James William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Will, Bob [Schlumberger, Houston, TX (United States); Zaluski, Wade [Schlumberger, Houston, TX (United States); Bowen, David [Montana State Univ., Bozeman, MT (United States); DeVault, Brian [Vecta Oil and Gas, Dallas, TX (United States); Duguid, Andrew [Battelle Memorial Inst., Columbus, OH (United States); Spangler, Lee [Montana State Univ., Bozeman, MT (United States); Stauffer, Philip H. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-12-22

In this report, we describe risk assessment work done using the National Risk Assessment Partnership (NRAP) applied to CO₂ storage at Kevin Dome, Montana. Geologic CO₂ sequestration in saline aquifers poses certain risks including CO₂/brine leakage through wells or non-sealing faults into groundwater or to the land surface. These risks are difficult to quantify due to data availability and uncertainty. One solution is to explore the consequences of these limitations by running large numbers of numerical simulations on the primary CO2 injection reservoir, shallow reservoirs/aquifers, faults, and wells to assess leakage risks and uncertainties. However, a large number of full-physics simulations is usually too computationally expensive. The NRAP integrated assessment model (NRAP-IAM) uses reduced order models (ROMs) developed from full-physics simulations to address this issue. A powerful stochastic framework allows NRAPIAM to explore complex interactions among many uncertain variables and evaluate the likely performance of potential sequestration sites.

Development and application of 3-D fractal reservoir model based on collage theorem

Energy Technology Data Exchange (ETDEWEB)

Kim, I.K.; Kim, K.S.; Sung, W.M. [Hanyang Univ., Seoul (Korea, Republic of)

1995-04-30

Reservoir characterization is the essential process to accurately evaluate the reservoir and has been conducted by geostatistical method, SRA algorithm, and etc. The characterized distribution of heterogeneous property by these methods shows randomly distributed phenomena, and does not present anomalous shape of property variation at discontinued space as compared with the observed shape in nature. This study proposed a new algorithm of fractal concept based on collage theorem, which can virtually present not only geometric shape of irregular and anomalous pore structures or coastlines, but also property variation for discontinuously observed data. With a basis of fractal concept, three dimensional fractal reservoir model was developed to more accurately characterize the heterogeneous reservoir. We performed analysis of pre-predictable hypothetically observed permeability data by using the fractal reservoir model. From the results, we can recognize that permeability distributions in the areal view or the cross-sectional view were consistent with the observed data. (author). 8 refs., 1 tab., 6 figs.

Bioremediation of a diesel fuel contaminated aquifer: simulation studies in laboratory aquifer columns

Science.gov (United States)

Hess, A.; Höhener, P.; Hunkeler, D.; Zeyer, J.

1996-08-01

The in situ bioremediation of aquifers contaminated with petroleum hydrocarbons is commonly based on the infiltration of groundwater supplemented with oxidants (e.g., O 2, NO 3-) and nutrients (e.g., NH 4+, PO 43-). These additions stimulate the microbial activity in the aquifer and several field studies describing the resulting processes have been published. However, due to the heterogeneity of the subsurface and due to the limited number of observation wells usually available, these field data do not offer a sufficient spatial and temporal resolution. In this study, flow-through columns of 47-cm length equipped with 17 sampling ports were filled with homogeneously contaminated aquifer material from a diesel fuel contaminated in situ bioremediation site. The columns were operated over 96 days at 12°C with artificial groundwater supplemented with O 2, NO 3- and PO 43-. Concentration profiles of O 2, NO 3-, NO 2-, dissolved inorganic and organic carbon (DIC and DOC, respectively), protein, microbial cells and total residual hydrocarbons were measured. Within the first 12 cm, corresponding to a mean groundwater residence time of < 3.6 h, a steep O 2 decrease from 4.6 to < 0.3 mg l -1, denitrification, a production of DIC and DOC, high microbial cell numbers and a high removal of hydrocarbons were observed. Within a distance of 24 to 40.5 cm from the infiltration, O 2 was below 0.1 mg l -1 and a denitrifying activity was found. In the presence and in the absence of O 2, n-alkanes were preferentially degraded compared to branched alkanes. The results demonstrate that: (1) infiltration of aerobic groundwater into columns filled with aquifer material contaminated with hydrocarbons leads to a rapid depletion of O 2; (2) O 2 and NO 3- can serve as oxidants for the mineralization of hydrocarbons; and (3) the modelling of redox processes in aquifers has to consider denitrifying activity in presence of O 2.

Environmental and Water Quality Operational Studies. General Guidelines for Monitoring Contaminants in Reservoirs

Science.gov (United States)

1986-02-01

espacially trte for the topics of sampling and analytical methods, statistical considerations, and the design of general water quality monitoring networks. For...and to the establishment and habitat differentiation of biological populations within reservoirs. Reservoir operatirn, esp- cially the timing...8217 % - - % properties of bottom sediments, as well as specific habitat associations of biological populations of reservoirs. Thus, such heterogeneities

Architecture and reservoir quality of low-permeable Eocene lacustrine turbidite sandstone from the Dongying Depression, East China

Science.gov (United States)

Munawar, Muhammad Jawad; Lin, Chengyan; Chunmei, Dong; Zhang, Xianguo; Zhao, Haiyan; Xiao, Shuming; Azeem, Tahir; Zahid, Muhammad Aleem; Ma, Cunfei

2018-05-01

The architecture and quality of lacustrine turbidites that act as petroleum reservoirs are less well documented. Reservoir architecture and multiscale heterogeneity in turbidites represent serious challenges to production performance. Additionally, establishing a hierarchy profile to delineate heterogeneity is a challenging task in lacustrine turbidite deposits. Here, we report on the turbidites in the middle third member of the Eocene Shahejie Formation (Es3), which was deposited during extensive Middle to Late Eocene rifting in the Dongying Depression. Seismic records, wireline log responses, and core observations were integrated to describe the reservoir heterogeneity by delineating the architectural elements, sequence stratigraphic framework and lithofacies assemblage. A petrographic approach was adopted to constrain microscopic heterogeneity using an optical microscope, routine core analyses and X-ray diffraction (XRD) analyses. The Es3m member is interpreted as a sequence set composed of four composite sequences: CS1, CS2, CS3 and CS4. A total of forty-five sequences were identified within these four composite sequences. Sand bodies were mainly deposited as channels, levees, overbank splays, lobes and lobe fringes. The combination of fining-upward and coarsening-upward lithofacies patterns in the architectural elements produces highly complex composite flow units. Microscopic heterogeneity is produced by diagenetic alteration processes (i.e., feldspar dissolution, authigenic clay formation and quartz cementation). The widespread kaolinization of feldspar and mobilization of materials enhanced the quality of the reservoir by producing secondary enlarged pores. In contrast, the formation of pore-filling authigenic illite and illite/smectite clays reduced its permeability. Recovery rates are higher in the axial areas and smaller in the marginal areas of architectural elements. This study represents a significant insight into the reservoir architecture and

Testing alternative conceptual models of seawater intrusion in a coastal aquifer using computer simulation, southern California, USA

Science.gov (United States)

Nishikawa, Tracy

1997-01-01

Two alternative conceptual models of the physical processes controlling seawater intrusion in a coastal basin in California, USA, were tested to identify a likely principal pathway for seawater intrusion. The conceptual models were tested by using a two-dimensional, finite-element groundwater flow and transport model. This pathway was identified by the conceptual model that best replicated the historical data. The numerical model was applied in cross section to a submarine canyon that is a main avenue for seawater to enter the aquifer system underlying the study area. Both models are characterized by a heterogeneous, layered, water-bearing aquifer. However, the first model is characterized by flat-lying aquifer layers and by a high value of hydraulic conductivity in the basal aquifer layer, which is thought to be a principal conduit for seawater intrusion. The second model is characterized by offshore folding, which was modeled as a very nearshore outcrop, thereby providing a shorter path for seawater to intrude. General conclusions are that: 1) the aquifer system is best modeled as a flat, heterogeneous, layered system; 2) relatively thin basal layers with relatively high values of hydraulic conductivity are the principal pathways for seawater intrusion; and 3) continuous clay layers of low hydraulic conductivity play an important role in controlling the movement of seawater.

Hydrogeological impacts evaluation like a subsidy for the hydroelectric reservoir installation in the Sao Paulo State, Brazil

International Nuclear Information System (INIS)

Albuquerque Filho, Jose Luiz; Bottura, Joao Alberto; Borin Junior, Tarcisio; Correa, Wilson Aparecido Garcia

1994-01-01

Hydrogeological studies developed in the influence areas of the big reservoirs at the Sao Paulo State, Sao Paulo/Mato Grosso do Sul and Sao Paulo/Parana, dedicated to the pre-filling situation evaluation, facilitated the preventive, corrective or alleviative actions adoption of the possible alterations in the adjacent free aquifers and, consequently, in the land use and occupation, as well as the planning of the rational usage of non-occupied areas in the reservoir margin. It presents the origin, the history and the objectives of the studies as well as the foreseen and confirmed hydrogeological impacts in monitored reservoirs

Integrating non-colocated well and geophysical data to capture subsurface heterogeneity at an aquifer recharge and recovery site

Science.gov (United States)

Gottschalk, Ian P.; Hermans, Thomas; Knight, Rosemary; Caers, Jef; Cameron, David A.; Regnery, Julia; McCray, John E.

2017-12-01

Geophysical data have proven to be very useful for lithological characterization. However, quantitatively integrating the information gained from acquiring geophysical data generally requires colocated lithological and geophysical data for constructing a rock-physics relationship. In this contribution, the issue of integrating noncolocated geophysical and lithological data is addressed, and the results are applied to simulate groundwater flow in a heterogeneous aquifer in the Prairie Waters Project North Campus aquifer recharge site, Colorado. Two methods of constructing a rock-physics transform between electrical resistivity tomography (ERT) data and lithology measurements are assessed. In the first approach, a maximum likelihood estimation (MLE) is used to fit a bimodal lognormal distribution to horizontal crosssections of the ERT resistivity histogram. In the second approach, a spatial bootstrap is applied to approximate the rock-physics relationship. The rock-physics transforms provide soft data for multiple point statistics (MPS) simulations. Subsurface models are used to run groundwater flow and tracer test simulations. Each model's uncalibrated, predicted breakthrough time is evaluated based on its agreement with measured subsurface travel time values from infiltration basins to selected groundwater recovery wells. We find that incorporating geophysical information into uncalibrated flow models reduces the difference with observed values, as compared to flow models without geophysical information incorporated. The integration of geophysical data also narrows the variance of predicted tracer breakthrough times substantially. Accuracy is highest and variance is lowest in breakthrough predictions generated by the MLE-based rock-physics transform. Calibrating the ensemble of geophysically constrained models would help produce a suite of realistic flow models for predictive purposes at the site. We find that the success of breakthrough predictions is highly

Geological heterogeneity: Goal-oriented simplification of structure and characterization needs

Science.gov (United States)

Savoy, Heather; Kalbacher, Thomas; Dietrich, Peter; Rubin, Yoram

2017-11-01

Geological heterogeneity, i.e. the spatial variability of discrete hydrogeological units, is investigated in an aquifer analog of glacio-fluvial sediments to determine how such a geological structure can be simplified for characterization needs. The aquifer analog consists of ten hydrofacies whereas the scarcity of measurements in typical field studies precludes such detailed spatial models of hydraulic properties. Of particular interest is the role of connectivity of the hydrofacies structure, along with its effect on the connectivity of mass transport, in site characterization for predicting early arrival times. Transport through three realizations of the aquifer analog is modeled with numerical particle tracking to ascertain the fast flow channel through which early arriving particles travel. Three simplification schemes of two-facies models are considered to represent the aquifer analogs, and the velocity within the fast flow channel is used to estimate the apparent hydraulic conductivity of the new facies. The facies models in which the discontinuous patches of high hydraulic conductivity are separated from the rest of the domain yield the closest match in early arrival times compared to the aquifer analog, but assuming a continuous high hydraulic conductivity channel connecting these patches yields underestimated early arrivals times within the range of variability between the realizations, which implies that the three simplification schemes could be advised but pose different implications for field measurement campaigns. Overall, the results suggest that the result of transport connectivity, i.e. early arrival times, within realistic geological heterogeneity can be conserved even when the underlying structural connectivity is modified.

A Simple Model to Describe the Relationship among Rainfall, Groundwater and Land Subsidence under a Heterogeneous Aquifer

Science.gov (United States)

Zheng, Y. Y.; Chen, Y. L.; Lin, H. R.; Huang, S. Y.; Yeh, T. C. J.; Wen, J. C.

2017-12-01

Land subsidence is a very serious problem of Zhuoshui River alluvial fan, Taiwan. The main reason of land subsidence is a compression of soil, but the compression measured in the wide area is very extensive (Maryam et al., 2013; Linlin et al., 2014). Chen et al. [2010] studied the linear relationship between groundwater level and subsurface altitude variations from Global Positioning System (GPS) station in Zhuoshui River alluvial fan. But the subsurface altitude data were only from two GPS stations. Their distributions are spared and small, not enough to express the altitude variations of Zhuoshui River alluvial fan. Hung et al. [2011] used Interferometry Synthetic Aperture Radar (InSAR) to measure the surface subsidence in Zhuoshui River alluvial fan, but haven't compared with groundwater level. The study compares the correlation between rainfall events and groundwater level and compares the correlation between groundwater level and subsurface altitude, these two correlation affected by heterogeneous soil. From these relationships, a numerical model is built to simulate the land subsidence variations and estimate the coefficient of aquifer soil compressibility. Finally, the model can estimate the long-term land subsidence. Keywords: Land Subsidence, InSAR, Groundwater Level, Numerical Model, Correlation Analyses

A coupling alternative to reactive transport simulations for long-term prediction of chemical reactions in heterogeneous CO2 storage systems

Directory of Open Access Journals (Sweden)

M. De Lucia

2015-02-01

Full Text Available Fully coupled, multi-phase reactive transport simulations of CO2 storage systems can be approximated by a simplified one-way coupling of hydrodynamics and reactive chemistry. The main characteristics of such systems, and hypotheses underlying the proposed alternative coupling, are (i that the presence of CO2 is the only driving force for chemical reactions and (ii that its migration in the reservoir is only marginally affected by immobilisation due to chemical reactions. In the simplified coupling, the exposure time to CO2 of each element of the hydrodynamic grid is estimated by non-reactive simulations and the reaction path of one single batch geochemical model is applied to each grid element during its exposure time. In heterogeneous settings, analytical scaling relationships provide the dependency of velocity and amount of reactions to porosity and gas saturation. The analysis of TOUGHREACT fully coupled reactive transport simulations of CO2 injection in saline aquifer, inspired to the Ketzin pilot site (Germany, both in homogeneous and heterogeneous settings, confirms that the reaction paths predicted by fully coupled simulations in every element of the grid show a high degree of self-similarity. A threshold value for the minimum concentration of dissolved CO2 considered chemically active is shown to mitigate the effects of the discrepancy between dissolved CO2 migration in non-reactive and fully coupled simulations. In real life, the optimal threshold value is unknown and has to be estimated, e.g. by means of 1-D or 2-D simulations, resulting in an uncertainty ultimately due to the process de-coupling. However, such uncertainty is more than acceptable given that the alternative coupling enables using grids of the order of millions of elements, profiting from much better description of heterogeneous reservoirs at a fraction of the calculation time of fully coupled models.

Numerical Simulation of Natural Convection in Heterogeneous Porous media for CO2 Geological Storage

NARCIS (Netherlands)

Ranganathan, P.; Farajzadeh, R.; Bruining, J.; Zitha, P.L.J.

2012-01-01

We report a modeling and numerical simulation study of density-driven natural convection during geological CO2 storage in heterogeneous formations. We consider an aquifer or depleted oilfield overlain by gaseous CO2, where the water density increases due to CO2 dissolution. The heterogeneity of the

FEWA: a Finite Element model of Water flow through Aquifers

International Nuclear Information System (INIS)

Yeh, G.T.; Huff, D.D.

1983-11-01

This report documents the implementation and demonstration of a Finite Element model of Water flow through Aquifers (FEWA). The particular features of FEWA are its versatility and flexibility to deal with as many real-world problems as possible. Point as well as distributed sources/sinks are included to represent recharges/pumpings and rainfall infiltrations. All sources/sinks can be transient or steady state. Prescribed hydraulic head on the Dirichlet boundaries and fluxes on Neumann or Cauchy boundaries can be time-dependent or constant. Source/sink strength over each element and node, hydraulic head at each Dirichlet boundary node, and flux at each boundary segment can vary independently of each other. Either completely confined or completely unconfined aquifers, or partially confined and partially unconfined aquifers can be dealt with effectively. Discretization of a compound region with very irregular curved boundaries is made easy by including both quadrilateral and triangular elements in the formulation. Large-field problems can be solved efficiently by including a pointwise iterative solution strategy as an optional alternative to the direct elimination solution method for the matrix equation approximating the partial differential equation of groundwater flow. FEWA also includes transient flow through confining leaky aquifers lying above and/or below the aquifer of interest. The model is verified against three simple cases to which analytical solutions are available. It is then demonstrated by two examples of how the model can be applied to heterogeneous and anisotropic aquifers with transient boundary conditions, time-dependent sources/sinks, and confining aquitards for a confined aquifer of variable thickness and for a free surface problem in an unconfined aquifer, respectively. 20 references, 25 figures, 8 tables

FEWA: a Finite Element model of Water flow through Aquifers

Energy Technology Data Exchange (ETDEWEB)

Yeh, G.T.; Huff, D.D.

1983-11-01

This report documents the implementation and demonstration of a Finite Element model of Water flow through Aquifers (FEWA). The particular features of FEWA are its versatility and flexibility to deal with as many real-world problems as possible. Point as well as distributed sources/sinks are included to represent recharges/pumpings and rainfall infiltrations. All sources/sinks can be transient or steady state. Prescribed hydraulic head on the Dirichlet boundaries and fluxes on Neumann or Cauchy boundaries can be time-dependent or constant. Source/sink strength over each element and node, hydraulic head at each Dirichlet boundary node, and flux at each boundary segment can vary independently of each other. Either completely confined or completely unconfined aquifers, or partially confined and partially unconfined aquifers can be dealt with effectively. Discretization of a compound region with very irregular curved boundaries is made easy by including both quadrilateral and triangular elements in the formulation. Large-field problems can be solved efficiently by including a pointwise iterative solution strategy as an optional alternative to the direct elimination solution method for the matrix equation approximating the partial differential equation of groundwater flow. FEWA also includes transient flow through confining leaky aquifers lying above and/or below the aquifer of interest. The model is verified against three simple cases to which analytical solutions are available. It is then demonstrated by two examples of how the model can be applied to heterogeneous and anisotropic aquifers with transient boundary conditions, time-dependent sources/sinks, and confining aquitards for a confined aquifer of variable thickness and for a free surface problem in an unconfined aquifer, respectively. 20 references, 25 figures, 8 tables.

CHARACTERIZATION OF SANDSTONE RESERVOIRS FOR ENHANCED OIL RECOVERY: THE PERMIAN UPPER MINNELUSA FORMATION, POWDER RIVER BASIN, WYOMING.

Science.gov (United States)

Schenk, C.J.; Schmoker, J.W.; Scheffler, J.M.

1986-01-01

Upper Minnelusa sandstones form a complex group of reservoirs because of variations in regional setting, sedimentology, and diagenetic alteration. Structural lineaments separate the reservoirs into northern and southern zones. Production in the north is from a single pay sand, and in the south from multi-pay sands due to differential erosion on top of the Upper Minnelusa. The intercalation of eolian dune, interdune, and sabkha sandstones with marine sandstones, carbonates, and anhydrites results in significant reservoir heterogeneity. Diagenetic alterations further enhance heterogeneity, because the degree of cementation and dissolution is partly facies-related.

Three-dimensional audio-magnetotelluric sounding in monitoring coalbed methane reservoirs

Science.gov (United States)

Wang, Nan; Zhao, Shanshan; Hui, Jian; Qin, Qiming

2017-03-01

Audio-magnetotelluric (AMT) sounding is widely employed in rapid resistivity delineation of objective geometry in near surface exploration. According to reservoir patterns and electrical parameters obtained in Qinshui Basin, China, two-dimensional and three-dimensional synthetic "objective anomaly" models were designed and inverted with the availability of a modular system for electromagnetic inversion (ModEM). The results revealed that 3-D full impedance inversion yielded the subsurface models closest to synthetic models. One or more conductive targets were correctly recovered. Therefore, conductive aquifers in the study area, including hydrous coalbed methane (CBM) reservoirs, were suggested to be the interpretation signs for reservoir characterization. With the aim of dynamic monitoring of CBM reservoirs, the AMT surveys in continuous years (June 2013-May 2015) were carried out. 3-D inversion results demonstrated that conductive anomalies accumulated around the producing reservoirs at the corresponding depths if CBM reservoirs were in high water production rates. In contrast, smaller conductive anomalies were generally identical with rapid gas production or stopping production of reservoirs. These analyses were in accordance with actual production history of CBM wells. The dynamic traces of conductive anomalies revealed that reservoir water migrated deep or converged in axial parts and wings of folds, which contributed significantly to formations of CBM traps. Then the well spacing scenario was also evaluated based on the dynamic production analysis. Wells distributed near closed faults or flat folds, rather than open faults, had CBM production potential to ascertain stable gas production. Therefore, three-dimensional AMT sounding becomes an attractive option with the ability of dynamic monitoring of CBM reservoirs, and lays a solid foundation of quantitative evaluation of reservoir parameters.

Facies sedimentology, mineralogy and genetic stratigraphy of the lower-Lias silici-clastic reservoirs of Cere-La-Ronde; Sedimentologie de facies, mineralogie et stratigraphie genetique des reservoirs silicoclastiques du Lias inferieur de Cere-La-Ronde

Energy Technology Data Exchange (ETDEWEB)

Geiller, M.

1997-11-21

Some sandstone reservoirs in the South West of the Parisian Basin (Sologne) are used for gas storage in the underground aquifer by GDF. The study aims to reconstruct the geometry of these reservoirs and to establish the factors controlling their deposition in the Sologne basin during Rhaetian and Hettangian times. This study combines palynological, sedimentological, mineralogical and sequential analyses. It is applied to channel deposits as well as to flood-plain and over-bank deposits which are rarely considered. The formations are deposited in a continental transgressive context associated to a decreasing subsidence. The different depositional environments varied from the alluvial fan to the coastal plain with different intermediate alluvial plains. They get organized in three depositional profiles which are emphasized by hydrodynamic discontinuities due to irreversible modifications in depositional conditions. The clayey associations change with each depositional profile according to detrital source modifications. They characterize discontinuities due to geodynamic events affecting the Sologne basin (depositional profile changes, pedogenesis). In this continental context, the genetic sequences record a cycle of variation of the river longitudinal profile slope. They determine the sediments geometry which results from the relative sea-level variations. Local tectonics creates an heterogenous subsidence and consequently controls the distribution of the sediments. During tectonic instability periods, the subsiding areas migrate while they do not during tectonic stability periods. The latter end with irreversible change in depositional profile. (author) 135 refs.

Numerical Simulation of Borehole Flow in Deep Monitor Wells, Pearl Harbor Aquifer, Oahu, Hawaii

Science.gov (United States)

Rotzoll, K.; Oki, D. S.; El-Kadi, A. I.

2010-12-01

Salinity profiles collected from uncased deep monitor wells are commonly used to monitor freshwater-lens thickness in coastal aquifers. However, vertical flow in these wells can cause the measured salinity to differ from salinity in the adjacent aquifer. Substantial borehole flow has been observed in uncased wells in the Pearl Harbor aquifer, Oahu, Hawaii. A numerical modeling approach, incorporating aquifer hydraulic characteristics and recharge rates representative of the Pearl Harbor aquifer, was used to evaluate the effects of borehole flow on measured salinity profiles from deep monitor wells. Borehole flow caused by vertical hydraulic gradients associated with the natural regional groundwater-flow system and local groundwater withdrawals was simulated. Model results were used to estimate differences between vertical salinity profiles in deep monitor wells and the adjacent aquifer in areas of downward, horizontal, and upward flow within the regional flow system—for cases with and without nearby pumped wells. Aquifer heterogeneity, represented in the model as layers of contrasting permeability, was incorporated in model scenarios. Results from this study provide insight into the magnitude of the differences between vertical salinity profiles from deep monitor wells and the salinity distributions in the aquifers. These insights are relevant and are critically needed for management and predictive modeling purposes.

Advanced Techniques for Reservoir Simulation and Modeling of Non-Conventional Wells

Energy Technology Data Exchange (ETDEWEB)

Durlofsky, Louis J.

2000-08-28

This project targets the development of (1) advanced reservoir simulation techniques for modeling non-conventional wells; (2) improved techniques for computing well productivity (for use in reservoir engineering calculations) and well index (for use in simulation models), including the effects of wellbore flow; and (3) accurate approaches to account for heterogeneity in the near-well region.

Carbon Sequestration in Unconventional Reservoirs: Geophysical, Geochemical and Geomechanical Considerations

Science.gov (United States)

Zakharova, Natalia V.

In the face of the environmental challenges presented by the acceleration of global warming, carbon capture and storage, also called carbon sequestration, may provide a vital option to reduce anthropogenic carbon dioxide emissions, while meeting the world's energy demands. To operate on a global scale, carbon sequestration would require thousands of geologic repositories that could accommodate billions of tons of carbon dioxide per year. In order to reach such capacity, various types of geologic reservoirs should be considered, including unconventional reservoirs such as volcanic rocks, fractured formations, and moderate-permeability aquifers. Unconventional reservoirs, however, are characterized by complex pore structure, high heterogeneity, and intricate feedbacks between physical, chemical and mechanical processes, and their capacity to securely store carbon emissions needs to be confirmed. In this dissertation, I present my contribution toward the understanding of geophysical, geochemical, hydraulic, and geomechanical properties of continental basalts and fractured sedimentary formations in the context of their carbon storage capacity. The data come from two characterization projects, in the Columbia River Flood Basalt in Washington and the Newark Rift Basin in New York, funded by the U.S. Department of Energy through Big Sky Carbon Sequestration Partnerships and TriCarb Consortium for Carbon Sequestration. My work focuses on in situ analysis using borehole geophysical measurements that allow for detailed characterization of formation properties on the reservoir scale and under nearly unaltered subsurface conditions. The immobilization of injected CO2 by mineralization in basaltic rocks offers a critical advantage over sedimentary reservoirs for long-term CO2 storage. Continental flood basalts, such as the Columbia River Basalt Group, possess a suitable structure for CO2 storage, with extensive reservoirs in the interflow zones separated by massive impermeable

Simulation of geothermal water extraction in heterogeneous reservoirs using dynamic unstructured mesh optimisation

Science.gov (United States)

Salinas, P.; Pavlidis, D.; Jacquemyn, C.; Lei, Q.; Xie, Z.; Pain, C.; Jackson, M.

2017-12-01

It is well known that the pressure gradient into a production well increases with decreasing distance to the well. To properly capture the local pressure drawdown into the well a high grid or mesh resolution is required; moreover, the location of the well must be captured accurately. In conventional simulation models, the user must interact with the model to modify grid resolution around wells of interest, and the well location is approximated on a grid defined early in the modelling process.We report a new approach for improved simulation of near wellbore flow in reservoir scale models through the use of dynamic mesh optimisation and the recently presented double control volume finite element method. Time is discretized using an adaptive, implicit approach. Heterogeneous geologic features are represented as volumes bounded by surfaces. Within these volumes, termed geologic domains, the material properties are constant. Up-, cross- or down-scaling of material properties during dynamic mesh optimization is not required, as the properties are uniform within each geologic domain. A given model typically contains numerous such geologic domains. Wells are implicitly coupled with the domain, and the fluid flows is modelled inside the wells. The method is novel for two reasons. First, a fully unstructured tetrahedral mesh is used to discretize space, and the spatial location of the well is specified via a line vector, ensuring its location even if the mesh is modified during the simulation. The well location is therefore accurately captured, the approach allows complex well trajectories and wells with many laterals to be modelled. Second, computational efficiency is increased by use of dynamic mesh optimization, in which an unstructured mesh adapts in space and time to key solution fields (preserving the geometry of the geologic domains), such as pressure, velocity or temperature, this also increases the quality of the solutions by placing higher resolution where required

Potential water supply of a small reservoir and alluvial aquifer system in southern Zimbabwe

NARCIS (Netherlands)

de Hamer, W.; Love, D.; Owen, R.; Booij, Martijn J.; Hoekstra, Arjen Ysbert

2008-01-01

Groundwater use by accessing alluvial aquifers of non-perennial rivers can be an important additional water resource in the semi-arid region of southern Zimbabwe. The research objective of the study was to calculate the potential water supply for the upper-Mnyabezi catchment under current conditions

Potential water supply of a small reservoir and alluvial aquifer system in southern Zimbabwe

NARCIS (Netherlands)

de Hamer, W.; Love, D.; Owen, R.; Booij, Martijn J.; Hoekstra, Arjen Ysbert

2007-01-01

Groundwater use by accessing alluvial aquifers of non‐perennial rivers can be an important additional water resource in the semi‐arid region of southern Zimbabwe. The research objective of the study was to calculate the potential water supply for the upper‐Mnyabezi catchment under current conditions

Preliminary formation analysis for compressed air energy storage in depleted natural gas reservoirs :

Energy Technology Data Exchange (ETDEWEB)

Gardner, William Payton

2013-06-01

The purpose of this study is to develop an engineering and operational understanding of CAES performance for a depleted natural gas reservoir by evaluation of relative permeability effects of air, water and natural gas in depleted natural gas reservoirs as a reservoir is initially depleted, an air bubble is created, and as air is initially cycled. The composition of produced gases will be evaluated as the three phase flow of methane, nitrogen and brine are modeled. The effects of a methane gas phase on the relative permeability of air in a formation are investigated and the composition of the produced fluid, which consists primarily of the amount of natural gas in the produced air are determined. Simulations of compressed air energy storage (CAES) in depleted natural gas reservoirs were carried out to assess the effect of formation permeability on the design of a simple CAES system. The injection of N2 (as a proxy to air), and the extraction of the resulting gas mixture in a depleted natural gas reservoir were modeled using the TOUGH2 reservoir simulator with the EOS7c equation of state. The optimal borehole spacing was determined as a function of the formation scale intrinsic permeability. Natural gas reservoir results are similar to those for an aquifer. Borehole spacing is dependent upon the intrinsic permeability of the formation. Higher permeability allows increased injection and extraction rates which is equivalent to more power per borehole for a given screen length. The number of boreholes per 100 MW for a given intrinsic permeability in a depleted natural gas reservoir is essentially identical to that determined for a simple aquifer of identical properties. During bubble formation methane is displaced and a sharp N2methane boundary is formed with an almost pure N2 gas phase in the bubble near the borehole. During cycling mixing of methane and air occurs along the boundary as the air bubble boundary moves. The extracted gas mixture changes as a

Analysis of aquifer tests conducted in boreholes USW WT-10, UE-25 WT No. 12, and USW SD-7, 1995-96, Yucca Mountain, Nevada

International Nuclear Information System (INIS)

O'Brien, G.M.

1997-01-01

Single-borehole aquifer tests were conducted in three boreholes in the Yucca Mountain area between March 1995 and January 1996 to obtain estimates of borehole specific capacity and aquifer transmissivity. Analysis of aquifer testing in borehole USW SD-7 also resulted in an estimate of reservoir volume. Aquifer-test data were analyzed with the Cooper and Jacob straight-line method, two modified Theis nonequilibrium equation solutions, and a modified reservoir-limit solution. The highest estimates of transmissivity were in borehole USW WT-10, completed in the Topopah Spring Tuff. Mean transmissivity, based on the results of three drawdown tests, was 1,600 meters squared per day. Mean specific capacity in borehole USW WT-10 after 5 hours of pumping was 1,100 meters squared per day, and was estimated to be 740 meters squared per day after 24 hours of pumping. Aquifer testing in borehole UE-25 WT No. 12 appeared to be significantly affected by well losses. A mean transmissivity of 7 meters squared per day was obtained on the basis of analysis of three drawdown tests in borehole UE-25 WT No. 12. Mean specific capacity in borehole UE-25 WT No. 12, after 24 hours of pumping, was 7 meters squared per day. Borehole UE-25 WT No. 12 seemed to be producing water from fractures that could provide only a limited amount of water to the borehole

Geological entropy and solute transport in heterogeneous porous media

Science.gov (United States)

Bianchi, Marco; Pedretti, Daniele

2017-06-01

We propose a novel approach to link solute transport behavior to the physical heterogeneity of the aquifer, which we fully characterize with two measurable parameters: the variance of the log K values (σY2), and a new indicator (HR) that integrates multiple properties of the K field into a global measure of spatial disorder or geological entropy. From the results of a detailed numerical experiment considering solute transport in K fields representing realistic distributions of hydrofacies in alluvial aquifers, we identify empirical relationship between the two parameters and the first three central moments of the distributions of arrival times of solute particles at a selected control plane. The analysis of experimental data indicates that the mean and the variance of the solutes arrival times tend to increase with spatial disorder (i.e., HR increasing), while highly skewed distributions are observed in more orderly structures (i.e., HR decreasing) or at higher σY2. We found that simple closed-form empirical expressions of the bivariate dependency of skewness on HR and σY2 can be used to predict the emergence of non-Fickian transport in K fields considering a range of structures and heterogeneity levels, some of which based on documented real aquifers. The accuracy of these predictions and in general the results from this study indicate that a description of the global variability and structure of the K field in terms of variance and geological entropy offers a valid and broadly applicable approach for the interpretation and prediction of transport in heterogeneous porous media.

Transient well flow in layered aquifer systems: the uniform well-face drawdown solution

Science.gov (United States)

Hemker, C. J.

1999-11-01

Previously a hybrid analytical-numerical solution for the general problem of computing transient well flow in vertically heterogeneous aquifers was proposed by the author. The radial component of flow was treated analytically, while the finite-difference technique was used for the vertical flow component only. In the present work the hybrid solution has been modified by replacing the previously assumed uniform well-face gradient (UWG) boundary condition in such a way that the drawdown remains uniform along the well screen. The resulting uniform well-face drawdown (UWD) solution also includes the effects of a finite diameter well, wellbore storage and a thin skin, while partial penetration and vertical heterogeneity are accommodated by the one-dimensional discretization. Solutions are proposed for well flow caused by constant, variable and slug discharges. The model was verified by comparing wellbore drawdowns and well-face flux distributions with published numerical solutions. Differences between UWG and UWD well flow will occur in all situations with vertical flow components near the well, which is demonstrated by considering: (1) partially penetrating wells in confined aquifers, (2) fully penetrating wells in unconfined aquifers with delayed response and (3) layered aquifers and leaky multiaquifer systems. The presented solution can be a powerful tool for solving many well-hydraulic problems, including well tests, flowmeter tests, slug tests and pumping tests. A computer program for the analysis of pumping tests, based on the hybrid analytical-numerical technique and UWG or UWD conditions, is available from the author.

MULTIDISCIPLINARY IMAGING OF ROCK PROPERTIES IN CARBONATE RESERVOIRS FOR FLOW-UNIT TARGETING

Energy Technology Data Exchange (ETDEWEB)

Stephen C. Ruppel

2005-02-01

Despite declining production rates, existing reservoirs in the US contain large quantities of remaining oil and gas that constitute a huge target for improved diagnosis and imaging of reservoir properties. The resource target is especially large in carbonate reservoirs, where conventional data and methodologies are normally insufficient to resolve critical scales of reservoir heterogeneity. The objectives of the research described in this report were to develop and test such methodologies for improved imaging, measurement, modeling, and prediction of reservoir properties in carbonate hydrocarbon reservoirs. The focus of the study is the Permian-age Fullerton Clear Fork reservoir of the Permian Basin of West Texas. This reservoir is an especially appropriate choice considering (a) the Permian Basin is the largest oil-bearing basin in the US, and (b) as a play, Clear Fork reservoirs have exhibited the lowest recovery efficiencies of all carbonate reservoirs in the Permian Basin.

Impact of mixing chemically heterogeneous groundwaters on the sustainability of an open-loop groundwater heat pump

Science.gov (United States)

Burté, L.; Farasin, J.; Cravotta, C., III; Gerard, M. F.; Cotiche Baranger, C.; Aquilina, L.; Le Borgne, T.

2017-12-01

Geothermal systems using shallow aquifers are commonly used for heating and cooling. The sustainability of these systems can be severely impacted by the occurrence of clogging process. The geothermal loop operation (including pumping of groundwater, filtering and heat extraction through exchangers and cooled water injection) can lead to an unexpected biogeochemical reactivity and scaling formation that can ultimately lead to the shutdown of the geothermal doublet. Here, we report the results of investigations carried out on a shallow geothermal doublet (dynamic). Hydrochemical data collected at the pumping well showed that groundwater was chemically heterogeneous long the 11 meters well screen. While the aquifer was dominantly oxic, a localized inflow of anoxic water was detected and evaluated to produce about 40% of the total flow . The mixture of chemically heterogeneous water induced by pumping lead to the oxidation of reductive species and thus to the formation of biogenic precipitates responsible for clogging. The impact of pumping waters of different redox potential and chemical characteristics was quantified by numerical modeling using PHREEQC. These results shows that natural chemical heterogeneity can occur at a small scale in heterogeneous aquifers and highlight the importance of their characterization during the production well testing and the geothermal loop operation in order to take preventive measures to avoid clogging.

Numerical simulation of pore size dependent anhydrite precipitation in geothermal reservoirs

Science.gov (United States)

Mürmann, Mario; Kühn, Michael; Pape, Hansgeorg; Clauser, Christoph

2013-04-01

cementation in a 2D hypothetical core flooding experiment. With this new approach cementation patterns observed in the Allermöhe core samples can be explained now. The obtained results show that the variation of fluid supersaturation within a pore governs spatially heterogeneous anhydrite cementation. This variation and the fluid velocity determine the precipitation. Our numerical simulation results clearly emphasize the necessity to consider the spatial variation of supersaturation on the pore scale. References Baermann A., Kroeger J., Taugs R., Wuestenhagen K., Zarth M. (2000) Anhydrite cementation in Rhaetian Sandstone in Hamburg - Morphology and Structures, Zeitschrift für Angewandte Geologie, 46(3), 138-143 (in German). Clauser C. (2003) Numerical Simulation of Reactive Flow in Hot Aquifers. SHEMAT and processing SHEMAT, Springer Publishers, Heidelberg. Emmanuel S., Berkowitz B. (2007) Effects of pore size controlled solubility on reactive transport in heterogeneous rock, Geophysical Research Letters, 34, L06404. Putnis A., Mauthe G. (2001) The effect of pore size on cementation in porous rocks, Geofluids, 1, 37-41. Wagner R., Kühn M., Meyn V., Pape H., Vath U., Clauser C. (2005) Numerical simulation of pore space clogging in geothermal reservoirs by precipitation of anhydrite. International Journal of Rock Mechanics and Mining Sciences 42, 1070-1081, doi: 10.1016/ j.ijrmms.2005.05.008.

Application of advanced reservoir characterization, simulation, and production optimization strategies to maximize recovery in slope and basin clastic reservoirs, west Texas (Delaware Basin). Annual progress report, March 31, 1995--March 31, 1996

Energy Technology Data Exchange (ETDEWEB)

Dutton, S.P.; Hovorka, S.D.; Cole, A.G.

1996-08-01

The objective of this Class III project is to demonstrate that detailed reservoir characterization of clastic reservoirs in basinal sandstones of the Delaware Mountain Group in the Delaware Basin of West Texas and New Mexico is a cost-effective way to recover more of the original oil in place by strategic infill-well placement and geologically based field development. Reservoirs in the Delaware Mountain Group have low producibility (average recovery <14 percent of the original oil in place) because of a high degree of vertical and lateral heterogeneity caused by depositional processes and post-depositional diagenetic modification. Detailed correlations of the Ramsey sandstone reservoirs in Geraldine Ford field suggest that lateral sandstone continuity is less than interpreted by previous studies. The degree of lateral heterogeneity in the reservoir sandstones suggests that they were deposited by eolian-derived turbidites. According to the eolian-derived turbidite model, sand dunes migrated across the exposed shelf to the shelf break during sea-level lowstands and provided well sorted sand for turbidity currents or grain flows into the deep basin.

A review on hydraulic fracturing of unconventional reservoir

Directory of Open Access Journals (Sweden)

Quanshu Li

2015-03-01

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

Dynamic Pore-Scale Imaging of Reactive Transport in Heterogeneous Carbonates at Reservoir Conditions Across Multiple Dissolution Regimes

Science.gov (United States)

Menke, H. P.; Bijeljic, B.; Andrew, M. G.; Blunt, M. J.

2014-12-01

Sequestering carbon in deep geologic formations is one way of reducing anthropogenic CO2 emissions. When supercritical CO2 mixes with brine in a reservoir, the acid generated has the potential to dissolve the surrounding pore structure. However, the magnitude and type of dissolution are condition dependent. Understanding how small changes in the pore structure, chemistry, and flow properties affect dissolution is paramount for successful predictive modelling. Both 'Pink Beam' synchrotron radiation and a Micro-CT lab source are used in dynamic X-ray microtomography to investigate the pore structure changes during supercritical CO2 injection in carbonate rocks of varying heterogeneity at high temperatures and pressures and various flow-rates. Three carbonate rock types were studied, one with a homogeneous pore structure and two heterogeneous carbonates. All samples are practically pure calcium carbonate, but have widely varying rock structures. Flow-rate was varied in three successive experiments by over an order of magnitude whlie keeping all other experimental conditions constant. A 4-mm carbonate core was injected with CO2-saturated brine at 10 MPa and 50oC. Tomographic images were taken at 30-second to 20-minute time-resolutions during a 2 to 4-hour injection period. A pore network was extracted using a topological analysis of the pore space and pore-scale flow modelling was performed directly on the binarized images with connected pathways and used to track the altering velocity distributions. Significant differences in dissolution type and magnitude were found for each rock type and flowrate. At the highest flow-rates, the homogeneous carbonate was seen to have predominately uniform dissolution with minor dissolution rate differences between the pores and pore throats. Alternatively, the heterogeneous carbonates which formed wormholes at high flow rates. At low flow rates the homogeneous rock developed wormholes, while the heterogeneous samples showed evidence

Transient well flow in layered aquifer systems: the uniform well-face drawdown solution.

NARCIS (Netherlands)

Hemker, C.J.

1999-01-01

Previously a hybrid analytical-numerical solution for the general problem of computing transient well flow in vertically heterogeneous aquifers was proposed by the author. The radial component of flow was treated analytically, while the finite-difference technique was used for the vertical flow

A fully-coupled discontinuous Galerkin spectral element method for two-phase flow in petroleum reservoirs

Science.gov (United States)

Taneja, Ankur; Higdon, Jonathan

2018-01-01

A high-order spectral element discontinuous Galerkin method is presented for simulating immiscible two-phase flow in petroleum reservoirs. The governing equations involve a coupled system of strongly nonlinear partial differential equations for the pressure and fluid saturation in the reservoir. A fully implicit method is used with a high-order accurate time integration using an implicit Rosenbrock method. Numerical tests give the first demonstration of high order hp spatial convergence results for multiphase flow in petroleum reservoirs with industry standard relative permeability models. High order convergence is shown formally for spectral elements with up to 8th order polynomials for both homogeneous and heterogeneous permeability fields. Numerical results are presented for multiphase fluid flow in heterogeneous reservoirs with complex geometric or geologic features using up to 11th order polynomials. Robust, stable simulations are presented for heterogeneous geologic features, including globally heterogeneous permeability fields, anisotropic permeability tensors, broad regions of low-permeability, high-permeability channels, thin shale barriers and thin high-permeability fractures. A major result of this paper is the demonstration that the resolution of the high order spectral element method may be exploited to achieve accurate results utilizing a simple cartesian mesh for non-conforming geological features. Eliminating the need to mesh to the boundaries of geological features greatly simplifies the workflow for petroleum engineers testing multiple scenarios in the face of uncertainty in the subsurface geology.

Induced groundwater flux by increases in the aquifer's total stress.

Science.gov (United States)

Chang, Ching-Min; Yeh, Hund-Der

2015-01-01

Fluid-filled granular soils experience changes in total stress because of earth and oceanic tides, earthquakes, erosion, sedimentation, and changes in atmospheric pressure. The pore volume may deform in response to the changes in stress and this may lead to changes in pore fluid pressure. The transient fluid flow can therefore be induced by the gradient in excess pressure in a fluid-saturated porous medium. This work demonstrates the use of stochastic methodology in prediction of induced one-dimensional field-scale groundwater flow through a heterogeneous aquifer. A closed-form of mean groundwater flux is developed to quantify the induced field-scale mean behavior of groundwater flow and analyze the impacts of the spatial correlation length scale of log hydraulic conductivity and the pore compressibility. The findings provided here could be useful for the rational planning and management of groundwater resources in aquifers that contain lenses with large vertical aquifer matrix compressibility values. © 2014, National Ground Water Association.

Influence of geologic layering on heat transport and storage in an aquifer thermal energy storage system

Science.gov (United States)

Bridger, D. W.; Allen, D. M.

2014-01-01

A modeling study was carried out to evaluate the influence of aquifer heterogeneity, as represented by geologic layering, on heat transport and storage in an aquifer thermal energy storage (ATES) system in Agassiz, British Columbia, Canada. Two 3D heat transport models were developed and calibrated using the flow and heat transport code FEFLOW including: a "non-layered" model domain with homogeneous hydraulic and thermal properties; and, a "layered" model domain with variable hydraulic and thermal properties assigned to discrete geological units to represent aquifer heterogeneity. The base model (non-layered) shows limited sensitivity for the ranges of all thermal and hydraulic properties expected at the site; the model is most sensitive to vertical anisotropy and hydraulic gradient. Simulated and observed temperatures within the wells reflect a combination of screen placement and layering, with inconsistencies largely explained by the lateral continuity of high permeability layers represented in the model. Simulation of heat injection, storage and recovery show preferential transport along high permeability layers, resulting in longitudinal plume distortion, and overall higher short-term storage efficiencies.

Status of groundwater levels and storage volume in the Equus Beds aquifer near Wichita, Kansas, January 2006 to January 2010

Science.gov (United States)

Hansen, Cristi V.; Aucott, Walter R.

2010-01-01

A part of the Equus Beds aquifer in southwestern Harvey County and northwestern Sedgwick County was developed to supply water to residents of Wichita and for irrigation in south-central Kansas. Groundwater pumping for city and agricultural use caused water levels to decline in a large part of the aquifer northwest of Wichita. In 1965, the city of Wichita began using water from Cheney Reservoir in addition to water from the Equus Beds aquifer to meet the city's increasing demand for water. Irrigation pumpage in the area increased substantially during the 1970s and 1980s and contributed to the water-level declines. Water-level declines reached their maximum to date in October 1992.

Use of static Quantitative Microbial Risk Assessment to determine pathogen risks in an unconfined carbonate aquifer used for Managed Aquifer Recharge.

Science.gov (United States)

Toze, Simon; Bekele, Elise; Page, Declan; Sidhu, Jatinder; Shackleton, Mark

2010-02-01

Managed Aquifer Recharge (MAR) is becoming a mechanism used for recycling treated wastewater and captured urban stormwater and is being used as a treatment barrier to remove contaminants such as pathogens from the recharged water. There is still a need, however, to demonstrate the effectiveness of MAR to reduce any residual risk of pathogens in the recovered water. A MAR research site recharging secondary treated wastewater in an unconfined carbonate aquifer was used in conjunction with a static Quantitative Microbial Risk Assessment (QMRA) to assess the microbial pathogen risk in the recovered water following infiltration and aquifer passage. The research involved undertaking a detailed hydrogeological assessment of the aquifer at the MAR site and determining the decay rates of reference pathogens from an in-situ decay study. These variables along with literature data were then used in the static QMRA which demonstrated that the recovered water at this site did not meet the Australian Guidelines for recycled water when used for differing private green space irrigation scenarios. The results also confirmed the importance of obtaining local hydrogeological data as local heterogeneity can influence of residence time in the aquifer which, in turn, influences the outcomes. The research demonstrated that a static QMRA can be used to determine the residual risk from pathogens in recovered water and showed that it can be a valuable tool in the preliminary design and operation of MAR systems and the incorporation of complementary engineered treatment processes to ensure that there is acceptable health risk from the recovered water. Crown Copyright 2009. Published by Elsevier Ltd. All rights reserved.

Interdisciplinary study of reservoir compartments and heterogeneity. Final report, October 1, 1993--December 31, 1996

Energy Technology Data Exchange (ETDEWEB)

Van Kirk, C.

1998-01-01

A case study approach using Terry Sandstone production from the Hambert-Aristocrat Field, Weld County, Colorado was used to document the process of integration. One specific project goal is to demonstrate how a multidisciplinary approach can be used to detect reservoir compartmentalization and improve reserve estimates. The final project goal is to derive a general strategy for integration for independent operators. Teamwork is the norm for the petroleum industry where teams of geologists, geophysicists, and petroleum engineers work together to improve profits through a better understanding of reservoir size, compartmentalization, and orientation as well as reservoir flow characteristics. In this manner, integration of data narrows the uncertainty in reserve estimates and enhances reservoir management decisions. The process of integration has proven to be iterative. Integration has helped identify reservoir compartmentalization and reduce the uncertainty in the reserve estimates. This research report documents specific examples of integration and the economic benefits of integration.

Numerical studies of CO2 and brine leakage into a shallow aquifer through an open wellbore

Science.gov (United States)

Wang, Jingrui; Hu, Litang; Pan, Lehua; Zhang, Keni

2018-03-01

Industrial-scale geological storage of CO2 in saline aquifers may cause CO2 and brine leakage from abandoned wells into shallow fresh aquifers. This leakage problem involves the flow dynamics in both the wellbore and the storage reservoir. T2Well/ECO2N, a coupled wellbore-reservoir flow simulator, was used to analyze CO2 and brine leakage under different conditions with a hypothetical simulation model in water-CO2-brine systems. Parametric studies on CO2 and brine leakage, including the salinity, excess pore pressure (EPP) and initially dissolved CO2 mass fraction, are conducted to understand the mechanism of CO2 migration. The results show that brine leakage rates increase proportionally with EPP and inversely with the salinity when EPP varies from 0.5 to 1.5 MPa; however, there is no CO2 leakage into the shallow freshwater aquifer if EPP is less than 0.5 MPa. The dissolved CO2 mass fraction shows an important influence on the CO2 plume, as part of the dissolved CO2 becomes a free phase. Scenario simulation shows that the gas lifting effect will significantly increase the brine leakage rate into the shallow freshwater aquifer under the scenario of 3.89% dissolved CO2 mass fraction. The equivalent porous media (EPM) approach used to model the wellbore flow has been evaluated and results show that the EPM approach could either under- or over-estimate brine leakage rates under most scenarios. The discrepancies become more significant if a free CO2 phase evolves. Therefore, a model that can correctly describe the complex flow dynamics in the wellbore is necessary for investigating the leakage problems.

A Numerical Study of Gas Injection and Caprock Leakage from Yort-e-Shah Aquifer in Iran

Directory of Open Access Journals (Sweden)

H. S. Rad

2017-08-01

Full Text Available In order to mitigate the adverse effects of global warming due to anthropogenic CO2 emission into the atmosphere, geological sequestration of CO2 into subsurface formations has been investigated by many studies over the last decade. However, selection of formations and sites for any field application is still open to debate. The most important properties of a formation suitable for carbon sequestration are those which impact the fluid flow processes. The injection or extraction of gas can change the pore pressure within the reservoir, which in turn results in redistribution of the stress field. These events may cause considerably leakage of the fluid into the surrounding geological formations or ground surface. The main objective of this paper is to evaluate the potential of Yort-e-Shah aquifer for CO2 storage, through a series of analyses with a simplified numerical model. The numerical results suggest that the optimum injection pressure in Yort-e-Shah aquifer is about 15.51 MPa with a safety factor of about 1.7. The results of the fluid pressure and gas plume expansion are presented. Also, an analysis was carried out for a case with leak through cap rock. When there is no leak, the pressure within the aquifer is stable, while on the other hand, the pressure in case of leakage is slightly smaller. In case of leakage, the pressure is lowest in the middle of the reservoir, mainly because the nodes at the middle of the aquifer are influenced by all the leakage points, while around the wellbore or near the end of gas plume, are affected less due to their longer distance to leakage points.

Spatial connectivity in a highly heterogeneous aquifer: From cores to preferential flow paths

Science.gov (United States)

Bianchi, M.; Zheng, C.; Wilson, C.; Tick, G.R.; Liu, Gaisheng; Gorelick, S.M.

2011-01-01

This study investigates connectivity in a small portion of the extremely heterogeneous aquifer at the Macrodispersion Experiment (MADE) site in Columbus, Mississippi. A total of 19 fully penetrating soil cores were collected from a rectangular grid of 4 m by 4 m. Detailed grain size analysis was performed on 5 cm segments of each core, yielding 1740 hydraulic conductivity (K) estimates. Three different geostatistical simulation methods were used to generate 3-D conditional realizations of the K field for the sampled block. Particle tracking calculations showed that the fastest particles, as represented by the first 5% to arrive, converge along preferential flow paths and exit the model domain within preferred areas. These 5% fastest flow paths accounted for about 40% of the flow. The distribution of preferential flow paths and particle exit locations is clearly influenced by the occurrence of clusters formed by interconnected cells with K equal to or greater than the 0.9 decile of the data distribution (10% of the volume). The fraction of particle paths within the high-K clusters ranges from 43% to 69%. In variogram-based K fields, some of the fastest paths are through media with lower K values, suggesting that transport connectivity may not require fully connected zones of relatively homogenous K. The high degree of flow and transport connectivity was confirmed by the values of two groups of connectivity indicators. In particular, the ratio between effective and geometric mean K (on average, about 2) and the ratio between the average arrival time and the arrival time of the fastest particles (on average, about 9) are consistent with flow and advective transport behavior characterized by channeling along preferential flow paths. ?? 2011 by the American Geophysical Union.

Geoscience/engineering characterization of the interwell environment in carbonate reservoirs based on outcrop analogs, Permian Basin, West Texas and New Mexico-stratigraphic hierarchy and cycle stacking facies distribution, and interwell-scale heterogeneity: Grayburg Formation, New Mexico. Final report

Energy Technology Data Exchange (ETDEWEB)

Barnaby, R.J.; Ward, W.B.; Jennings, J.W. Jr.

1997-06-01

The Grayburg Formation (middle Guadalupian) is a major producing interval in the Permian Basin and has yielded more than 2.5 billion barrels of oil in West Texas. Grayburg reservoirs have produced, on average, less than 30 percent of their original oil in place and are undergoing secondary and tertiary recovery. Efficient design of such enhanced recovery programs dictates improved geological models to better understand and predict reservoir heterogeneity imposed by depositional and diagenetic controls. The Grayburg records mixed carbonate-siliciclastic sedimentation on shallow-water platforms that rimmed the Delaware and Midland Basins. Grayburg outcrops in the Guadalupe and Brokeoff Mountains region on the northwest margin of the Delaware Basin present an opportunity to construct a detailed, three-dimensional image of the stratigraphic and facies architecture. This model can be applied towards improved description and characterization of heterogeneity in analogous Grayburg reservoirs. Four orders of stratigraphic hierarchy are recognized in the Grayburg Formation. The Grayburg represents a long-term composite sequence composed of four high-frequency sequences (HFS 1-4). Each HFS contains several composite cycles comprising two or more cycles that define intermediate-scale transgressive-regressive successions. Cycles are the smallest scale upward-shoaling vertical facies successions that can be recognized and correlated across various facies tracts. Cycles thus form the basis for establishing the detailed chronostratigraphic correlations needed to delineate facies heterogeneity.

Prediction of the thermohydraulic performance of porous-media reservoirs for compressed-air energy storage

Energy Technology Data Exchange (ETDEWEB)

Wiles, L.E.; McCann, R.A.

1981-09-01

The numerical modeling capability that has been developed at the Pacific Northwest Laboratory (PNL) for the prediction of the thermohydraulic performance of porous media reservoirs for compressed air energy storage (CAES) is described. The capability of the numerical models was demonstrated by application to a variety of parametric analyses and the support analyses for the CAES porous media field demonstration program. The demonstration site analyses include calculations for the displacement of aquifer water to develop the air storage zone, the potential for water coning, thermal development in the reservoir, and the dehydration of the near-wellbore region. Unique features of the demonstration site reservoir that affect the thermohydraulic performance are identified and contrasted against the predicted performance for conditions that would be considered more typical of a commercial CAES site.

Integrated Sedimentological Approach to Assess Reservoir Quality and Architecture of Khuff Carbonates: Outcrop Analog, Central Saudi Arabia

Science.gov (United States)

Osman, Mutsim; Abdullatif, Osman

2017-04-01

The Permian to Triassic Khuff carbonate reservoirs (and equivalents) in the Middle East are estimated to contain about 38.4% of the world's natural gas reserves. Excellent exposed outcrops in central Saudi Arabia provide good outcrop equivalents to subsurface Khuff reservoirs. This study conduct high resolution outcrop scale investigations on an analog reservoir for upper Khartam of Khuff Formation. The main objective is to reconstruct litho- and chemo- stratigraphic outcrop analog model that may serve to characterize reservoir high resolution (interwell) heterogeneity, continuity and architecture. Given the fact of the limitation of subsurface data and toolsin capturing interwell reservoir heterogeneity, which in turn increases the value of this study.The methods applied integrate sedimentological, stratigraphic petrographic, petrophysical data and chemical analyses for major, trace and rare earth elements. In addition, laser scanning survey (LIDAR) was also utilized in this study. The results of the stratigraphic investigations revealed that the lithofacies range from mudstone, wackestone, packestone and grainstone. These lithofacies represent environments ranging from supratidal, intertidal, subtidal and shoal complex. Several meter-scale and less high resolution sequences and composite sequences within 4th and 5th order cycles were also recognized in the outcrop analog. The lithofacies and architectural analysis revealed several vertically and laterally stacked sequences at the outcrop as revealed from the stratigraphic sections and the lidar scan. Chemostratigraphy is effective in identifying lithofacies and sequences within the outcrop analog. Moreover, different chemical signatures were also recognized and allowed establishing and correlating high resolution lithofacies, reservoir zones, layers and surfaces bounding reservoirs and non-reservoir zones at scale of meters or less. The results of this high resolution outcrop analog study might help to understand

Multi-scale nitrate transport in a sandstone aquifer system under intensive agriculture

Science.gov (United States)

Paradis, Daniel; Ballard, Jean-Marc; Lefebvre, René; Savard, Martine M.

2018-03-01

Nitrate transport in heterogeneous bedrock aquifers is influenced by mechanisms that operate at different spatial and temporal scales. To understand these mechanisms in a fractured sandstone aquifer with high porosity, a groundwater-flow and nitrate transport model—reproducing multiple hydraulic and chemical targets—was developed to explain the actual nitrate contamination observed in groundwater and surface water in a study area on Prince Edward Island, Canada. Simulations show that nitrate is leached to the aquifer year-round, with 61% coming from untransformed and transformed organic sources originating from fertilizers and manure. This nitrate reaches the more permeable shallow aquifer through fractures in weathered sandstone that represent only 1% of the total porosity (17%). Some of the nitrate reaches the underlying aquifer, which is less active in terms of groundwater flow, but most of it is drained to the main river. The river-water quality is controlled by the nitrate input from the shallow aquifer. Groundwater in the underlying aquifer, which has long residence times, is also largely influenced by the diffusion of nitrate in the porous sandstone matrix. Consequently, following a change of fertilizer application practices, water quality in domestic wells and the river would change rapidly due to the level of nitrate found in fractures, but a lag time of up to 20 years would be necessary to reach a steady level due to diffusion. This demonstrates the importance of understanding nitrate transport mechanisms when designing effective agricultural and water management plans to improve water quality.

Water resources management in karst aquifers - concepts and modeling approaches

Science.gov (United States)

Sauter, M.; Schmidt, S.; Abusaada, M.; Reimann, T.; Liedl, R.; Kordilla, J.; Geyer, T.

2011-12-01

Water resources management schemes generally imply the availability of a spectrum of various sources of water with a variability of quantity and quality in space and time, and the availability and suitability of storage facilities to cover various demands of water consumers on quantity and quality. Aquifers are generally regarded as suitable reservoirs since large volumes of water can be stored in the subsurface, water is protected from contamination and evaporation and the underground passage assists in the removal of at least some groundwater contaminants. Favorable aquifer properties include high vertical hydraulic conductivities for infiltration, large storage coefficients and not too large hydraulic gradients / conductivities. The latter factors determine the degree of discharge, i.e. loss of groundwater. Considering the above criteria, fractured and karstified aquifers appear to not really fulfill the respective conditions for storage reservoirs. Although infiltration capacity is relatively high, due to low storativity and high hydraulic conductivities, the small quantity of water stored is rapidly discharged. However, for a number of specific conditions, even karst aquifers are suitable for groundwater management schemes. They can be subdivided into active and passive management strategies. Active management options include strategies such as overpumping, i.e. the depletion of the karst water resources below the spring outflow level, the construction of subsurface dams to prevent rapid discharge. Passive management options include the optimal use of the discharging groundwater under natural discharge conditions. System models that include the superposition of the effect of the different compartments soil zone, epikarst, vadose and phreatic zone assist in the optimal usage of the available groundwater resources, while taking into account the different water reservoirs. The elaboration and implementation of groundwater protection schemes employing well

Flow to partially penetrating wells in unconfined heterogeneous aquifers: Mean head and interpretation of pumping tests

Science.gov (United States)

Dagan, G.; Lessoff, S. C.

2011-06-01

A partially penetrating well of length Lw and radius Rw starts to pump at constant discharge Qw at t = 0 from an unconfined aquifer of thickness D. The aquifer is of random and stationary conductivity characterized by KG (geometric mean), σY2 (log conductivity variance), and I and Iv (the horizontal and vertical integral scales). The flow problem is solved under a few simplifying assumptions commonly adopted in the literature for homogeneous media: Rw/Lw ≪ 1, linearization of the free surface condition, and constant drainable porosity n. Additionally, it is assumed that Rw/I well boundary conditions) and that a first-order approximation in σY2 (extended to finite σY2 on a conjectural basis) is adopted. The solution is obtained for the mean head field and the associated water table equation. The main result of the analysis is that the flow domain can be divided into three zones for : (1) the neighborhood of the well R ≪ I, where = (Qw/LwKA)h0(R, z, tKefuv/nD), with h0 being the zero-order solution pertaining to a homogeneous and isotropic aquifer, KA being the conductivity arithmetic mean, and Kefuv being the effective vertical conductivity in mean uniform flow, (2) an exterior zone R ⪆ I in which ?H? = (Qw/LwKefuh)h0(R?, z, tKefuv/nD), with Kefuh being the horizontal effective conductivity, and (3) an intermediate zone in which the solution requires a few numerical quadratures, not carried out here. The application to pumping tests reveals that identification of the aquifer parameters for homogeneous and anisotropic aquifers by commonly used methods can be applied for the drawdown measured in an observation well of length Low?Iv (to ensure exchange of space and ensemble head averages) in the second zone in order to identify Kefuh, Kefuv, and n. In contrast, the use of the drawdown in the well (first zone) leads to an overestimation of Kefuh by the factor KA/Kefuh.

Permeability model of tight reservoir sandstones combining core-plug and miniperm analysis of drillcore; longyearbyen co2lab, Svalbard

NARCIS (Netherlands)

Magnabosco, Cara; Braathen, Alvar; Ogata, Kei

2014-01-01

Permeability measurements in Mesozoic, low-permeability sandstone units within the strata cored in seven drillholes near Longyearbyen, Svalbard, have been analysed to assess the presence of aquifers and their potentials as reservoirs for the storage of carbon dioxide. These targeted sandstones are

Geological and production characteristics of strandplain/barrier island reservoirs in the United States

Energy Technology Data Exchange (ETDEWEB)

Cole, E.L.; Fowler, M.; Jackson, S.; Madden, M.P.; Reeves, T.K.; Salamy, S.P.; Young, M.A.

1994-12-01

The Department of Energy`s (DOE`s) primary mission in the oil research program is to maximize the economically and environmentally sound recovery of oil from domestic reservoirs and to preserve access to this resource. The Oil Recovery Field Demonstration Program supports DOE`s mission through cost-shared demonstrations of improved Oil Recovery (IOR) processes and reservoir characterization methods. In the past 3 years, the DOE has issued Program Opportunity Notices (PONs) seeking cost-shared proposals for the three highest priority, geologically defined reservoir classes. The classes have been prioritized based on resource size and risk of abandonment. This document defines the geologic, reservoir, and production characteristics of the fourth reservoir class, strandplain/barrier islands. Knowledge of the geological factors and processes that control formation and preservation of reservoir deposits, external and internal reservoir heterogeneities, reservoir characterization methodology, and IOR process application can be used to increase production of the remaining oil-in-place (IOR) in Class 4 reservoirs. Knowledge of heterogeneities that inhibit or block fluid flow is particularly critical. Using the TORIS database of 330 of the largest strandplain/barrier island reservoirs and its predictive and economic models, the recovery potential which could result from future application of IOR technologies to Class 4 reservoirs was estimated to be between 1.0 and 4.3 billion barrels, depending on oil price and the level of technology advancement. The analysis indicated that this potential could be realized through (1) infill drilling alone and in combination with polymer flooding and profile modification, (2) chemical flooding (sufactant), and (3) thermal processes. Most of this future potential is in Texas, Oklahoma, and the Rocky Mountain region. Approximately two-thirds of the potentially recoverable resource is at risk of abandonment by the year 2000.

Mines as lower reservoir of an UPSH (Underground Pumping Storage Hydroelectricity): groundwater impacts and feasibility

Science.gov (United States)

Bodeux, Sarah; Pujades, Estanislao; Orban, Philippe; Dassargues, Alain

2016-04-01

The energy framework is currently characterized by an expanding use of renewable sources. However, their intermittence could not afford a stable production according to the energy demand. Pumped Storage Hydroelectricity (PSH) is an efficient possibility to store and release electricity according to the demand needs. Because of the topographic and environmental constraints of classical PSH, new potential suitable sites are rare in countries whose topography is weak or with a high population density. Nevertheless, an innovative alternative is to construct Underground Pumped Storage Hydroelectricity (UPSH) plants by using old underground mine works as lower reservoir. In that configuration, large amount of pumped or injected water in the underground cavities would impact the groundwater system. A representative UPSH facility is used to numerically determine the interactions with surrounding aquifers Different scenarios with varying parameters (hydrogeological and lower reservoir characteristics, boundaries conditions and pumping/injection time-sequence) are computed. Analysis of the computed piezometric heads around the reservoir allows assessing the magnitude of aquifer response and the required time to achieve a mean pseudo-steady state under cyclic solicitations. The efficiency of the plant is also evaluated taking the leakage into the cavity into account. Combining these two outcomes, some criterions are identified to assess the feasibility of this type of projects within potential old mine sites from a hydrogeological point of view.

Estimation of Oil Production Rates in Reservoirs Exposed to Focused Vibrational Energy

KAUST Repository

Jeong, Chanseok

2014-01-01

Elastic wave-based enhanced oil recovery (EOR) is being investigated as a possible EOR method, since strong wave motions within an oil reservoir - induced by earthquakes or artificially generated vibrations - have been reported to improve the production rate of remaining oil from existing oil fields. To date, there are few theoretical studies on estimating how much bypassed oil within an oil reservoir could be mobilized by such vibrational stimulation. To fill this gap, this paper presents a numerical method to estimate the extent to which the bypassed oil is mobilized from low to high permeability reservoir areas, within a heterogeneous reservoir, via wave-induced cross-flow oscillation at the interface between the two reservoir permeability areas. This work uses the finite element method to numerically obtain the pore fluid wave motion within a one-dimensional fluid-saturated porous permeable elastic solid medium embedded in a non-permeable elastic semi-infinite solid. To estimate the net volume of mobilized oil from the low to the high permeability area, a fluid flow hysteresis hypothesis is adopted to describe the behavior at the interface between the two areas. Accordingly, the fluid that is moving from the low to the high permeability areas is assumed to transport a larger volume of oil than the fluid moving in the opposite direction. The numerical experiments were conducted by using a prototype heterogeneous oil reservoir model, subjected to ground surface dynamic loading operating at low frequencies (1 to 50 Hz). The numerical results show that a sizeable amount of oil could be mobilized via the elastic wave stimulation. It is observed that certain wave frequencies are more effective than others in mobilizing the remaining oil. We remark that these amplification frequencies depend on the formation’s elastic properties. This numerical work shows that the wave-based mobilization of the bypassed oil in a heterogeneous oil reservoir is feasible, especially

Evaluation of the operation of Yermasoyia surface and groundwater reservoirs

International Nuclear Information System (INIS)

Iacovides, I.S.

1988-07-01

The environmental isotope technique has been used in conjunction with hydrochemical methods to study the conjunctive use of surface and groundwater in the Yermasoyia area of Cyprus. The isotopes used in this study are 18 O, 2 H and 3 H. The isotopically enriched water in the Yermasoyia dam is released periodically in order to study the movement of the released water. From the stable isotopes and tritium data, it became evident that two regions can be distinguished in the aquifer, the Upper part and the Delta area. The secondary aquifer on either side of the river valley does not appear to receive any water from the seepage of the dam. The overall tracer average velocity in the aquifer was computed to be 16±3m per day and this is equivalent to a permeability of 160m per day. Water bodies originating from low frequency spills have been identified at the coast on the basis of oxygen-18 and tritium. A successful simulation of the reservoir for 1985 increased the confidence in the water balance and was used to verify the quantities estimated for evaporation and seepage. Refs, figs and tabs

Reactive transport impacts on recovered freshwater quality during multiple partially penetrating wells (MPPW-)ASR in a brackish heterogeneous aquifer

NARCIS (Netherlands)

Zuurbier, Koen G.; Hartog, Niels; Stuyfzand, Pieter J.

The use of multiple partially penetrating wells (MPPW) during aquifer storage and recovery (ASR) in brackish aquifers can significantly improve the recovery efficiency (RE) of unmixed injected water. The water quality changes by reactive transport processes in a field MPPW-ASR system and their

Carbonate reservoir characterization with lithofacies clustering and porosity prediction

International Nuclear Information System (INIS)

Al Moqbel, Abdulrahman; Wang, Yanghua

2011-01-01

One of the objectives in reservoir characterization is to quantitatively or semi-quantitatively map the spatial distribution of its heterogeneity and related properties. With the availability of 3D seismic data, artificial neural networks are capable of discovering the nonlinear relationship between seismic attributes and reservoir parameters. For a target carbonate reservoir, we adopt a two-stage approach to conduct characterization. First, we use an unsupervised neural network, the self-organizing map method, to classify the reservoir lithofacies. Then we apply a supervised neural network, the back-propagation algorithm, to quantitatively predict the porosity of the carbonate reservoir. Based on porosity maps at different time levels, we interpret the target reservoir vertically related to three depositional phases corresponding to, respectively, a lowstand system tract before sea water immersion, a highstand system tract when water covers organic deposits and a transition zone for the sea level falling. The highstand system is the most prospective zone, given the organic content deposited during this stage. The transition zone is also another prospective feature in the carbonate depositional system due to local build-ups

pressure distribution in a layered reservoir with gas-cap and bottom

African Journals Online (AJOL)

2012-07-02

Jul 2, 2012 ... Finally, only fluid ratios is recommended as adequate to reveal which ... pressure derivatives, interlayer cross flow, heterogeneity, reservoir characterization, pressure ... sure derivatives to thoroughly understand movement.

Hydrogeological Conditions of a Crystalline Aquifer: Simulation of Optimal Abstraction Rates under Scenarios of Reduced Recharge

Science.gov (United States)

Fynn, Obed Fiifi; Chegbeleh, Larry Pax; Nude, Prosper M.; Asiedu, Daniel K.

2013-01-01

A steady state numerical groundwater flow model has been calibrated to characterize the spatial distribution of a key hydraulic parameter in a crystalline aquifer in southwestern Ghana. This was to provide an initial basis for characterizing the hydrogeology of the terrain with a view to assisting in the large scale development of groundwater resources for various uses. The results suggest that the structural entities that control groundwater occurrence in the area are quite heterogeneous in their nature and orientation, ascribing hydraulic conductivity values in the range of 4.5 m/d to over 70 m/d to the simulated aquifer. Aquifer heterogeneities, coupled possibly with topographical trends, have led to the development of five prominent groundwater flowpaths in the area. Estimated groundwater recharge at calibration ranges between 0.25% and 9.13% of the total annual rainfall and appears to hold significant promise for large-scale groundwater development to support irrigation schemes. However, the model suggests that with reduced recharge by up to 30% of the current rates, the system can only sustain increased groundwater abstraction by up to 150% of the current abstraction rates. Prudent management of the resource will require a much more detailed hydrogeological study that identifies all the aquifers in the basin for the assessment of sustainable basin yield. PMID:24453882

Reservoir Identification: Parameter Characterization or Feature Classification

Science.gov (United States)

Cao, J.

2017-12-01

The ultimate goal of oil and gas exploration is to find the oil or gas reservoirs with industrial mining value. Therefore, the core task of modern oil and gas exploration is to identify oil or gas reservoirs on the seismic profiles. Traditionally, the reservoir is identify by seismic inversion of a series of physical parameters such as porosity, saturation, permeability, formation pressure, and so on. Due to the heterogeneity of the geological medium, the approximation of the inversion model and the incompleteness and noisy of the data, the inversion results are highly uncertain and must be calibrated or corrected with well data. In areas where there are few wells or no well, reservoir identification based on seismic inversion is high-risk. Reservoir identification is essentially a classification issue. In the identification process, the underground rocks are divided into reservoirs with industrial mining value and host rocks with non-industrial mining value. In addition to the traditional physical parameters classification, the classification may be achieved using one or a few comprehensive features. By introducing the concept of seismic-print, we have developed a new reservoir identification method based on seismic-print analysis. Furthermore, we explore the possibility to use deep leaning to discover the seismic-print characteristics of oil and gas reservoirs. Preliminary experiments have shown that the deep learning of seismic data could distinguish gas reservoirs from host rocks. The combination of both seismic-print analysis and seismic deep learning is expected to be a more robust reservoir identification method. The work was supported by NSFC under grant No. 41430323 and No. U1562219, and the National Key Research and Development Program under Grant No. 2016YFC0601

Sedimentological reservoir characteristics of the Paleocene fluvial/lacustrine Yabus Sandstone, Melut Basin, Sudan

Science.gov (United States)

Mahgoub, M. I.; Padmanabhan, E.; Abdullatif, O. M.

2016-11-01

Melut Basin in Sudan is regionally linked to the Mesozoic-Cenozoic Central and Western African Rift System (CWARS). The Paleocene Yabus Formation is the main oil producing reservoir in the basin. It is dominated by channel sandstone and shales deposited in fluvial/lacustrine environment during the third phase of rifting in the basin. Different scales of sedimentological heterogeneities influenced reservoir quality and architecture. The cores and well logs analyses revealed seven lithofacies representing fluvial, deltaic and lacustrine depositional environments. The sandstone is medium to coarse-grained, poorly to moderately-sorted and sub-angular to sub-rounded, arkosic-subarkosic to sublitharenite. On the basin scale, the Yabus Formation showed variation in sandstone bodies, thickness, geometry and architecture. On macro-scale, reservoir quality varies vertically and laterally within Yabus Sandstone where it shows progressive fining upward tendencies with different degrees of connectivity. The lower part of the reservoir showed well-connected and amalgamated sandstone bodies, the middle to the upper parts, however, have moderate to low sandstone bodies' connectivity and amalgamation. On micro-scale, sandstone reservoir quality is directly affected by textures and diagenetic changes such as compaction, cementation, alteration, dissolution and kaolinite clays pore fill and coat all have significantly reduced the reservoir porosity and permeability. The estimated porosity in Yabus Formation ranges from 2 to 20% with an average of 12%; while permeability varies from 200 to 500 mD and up to 1 Darcy. The understanding of different scales of sedimentological reservoir heterogeneities might contribute to better reservoir quality prediction, architecture, consequently enhancing development and productivity.

Risk-Based Management of Contaminated Groundwater: The Role of Geologic Heterogeneity, Exposure and Cancer Risk in Determining the Performance of Aquifer Remediation

International Nuclear Information System (INIS)

Maxwell, R.M.; Carle, S.F.; Tompson, A.F.B.

2000-01-01

The effectiveness of aquifer remediation is typically expressed in terms of a reduction in contaminant concentrations relative to a regulated maximum contaminant level (MCL), and is usually confined by sparse monitoring data and/or simple model calculations. Here, the effectiveness of remediation is examined from a risk-based perspective that goes beyond the traditional MCL concept. A methodology is employed to evaluate the health risk to individuals exposed to contaminated household water that is produced from groundwater. This approach explicitly accounts for differences in risk arising from variability in individual physiology and water use, the uncertainty in estimating chemical carcinogenesis for different individuals, and the uncertainties and variability in contaminant concentrations within groundwater. A hypothetical contamination scenario is developed as a case study in a saturated, alluvial aquifer underlying a real Superfund site. A baseline (unremediated) human exposure and health risk scenario, as induced by contaminated groundwater pumped from this site, is predicted and compared with a similar estimate based upon pump-and-treat exposure intervention. The predicted reduction in risk in the remediation scenario is not an equitable one-that is, it is not uniform to all individuals within a population and varies according to the level of uncertainty in prediction. The importance of understanding the detailed hydrogeologic connections that are established in the heterogeneous geologic regime between the contaminated source, municipal receptors, and remediation wells, and its relationship to this uncertainty is demonstrated. Using two alternative pumping rates, we develop cost-benefit curves based upon reduced exposure and risk to different individuals within the population, under the presence of uncertainty

Carbonate aquifers

Science.gov (United States)

Cunningham, Kevin J.; Sukop, Michael; Curran, H. Allen

2012-01-01

Only limited hydrogeological research has been conducted using ichnology in carbonate aquifer characterization. Regardless, important applications of ichnology to carbonate aquifer characterization include its use to distinguish and delineate depositional cycles, correlate mappable biogenically altered surfaces, identify zones of preferential groundwater flow and paleogroundwater flow, and better understand the origin of ichnofabric-related karst features. Three case studies, which include Pleistocene carbonate rocks of the Biscayne aquifer in southern Florida and Cretaceous carbonate strata of the Edwards–Trinity aquifer system in central Texas, demonstrate that (1) there can be a strong relation between ichnofabrics and groundwater flow in carbonate aquifers and (2) ichnology can offer a useful methodology for carbonate aquifer characterization. In these examples, zones of extremely permeable, ichnofabric-related macroporosity are mappable stratiform geobodies and as such can be represented in groundwater flow and transport simulations.

Field study of macrodispersion in a heterogeneous aquifer. 3

International Nuclear Information System (INIS)

Beard, L.M.; Stauffer, T.B.; MacIntyre, W.G.

1990-01-01

The Tennessee Valley Authority is conducting a second large-scale groundwater research study. In this experiment, dissolved tracers are being injected into a shallow alluvium aquifer. This study will support groundwater protection by making possible more effective design of waste storage facilities, improving monitoring systems, and designing better mitigation programs. The objectives of this study are to better understand the dominant physical and chemical factors affecting contaminant movement in groundwater. A data set will be provided for evaluating transport models and for assessing the reliability of laboratory measure parameters to predict transport. Tritiated water was used as the conservative, nonreactive tracer to overcome problems experienced with the use of bromide in the first experiment. Four non-conservative tracers (naphthalene, carbon 14-labeled para-xylene, benzene, and ortho-dichlorobenzene) were also injected. This paper describes initial laboratory tests and the design and implementation of the second natural gradient injection experiment. (Author) (13 refs., 5 figs., 4 tabs.)

Integration of electrical resistivity imaging and ground penetrating radar to investigate solution features in the Biscayne Aquifer

Science.gov (United States)

Yeboah-Forson, Albert; Comas, Xavier; Whitman, Dean

2014-07-01

The limestone composing the Biscayne Aquifer in southeast Florida is characterized by cavities and solution features that are difficult to detect and quantify accurately because of their heterogeneous spatial distribution. Such heterogeneities have been shown by previous studies to exert a strong influence in the direction of groundwater flow. In this study we use an integrated array of geophysical methods to detect the lateral extent and distribution of solution features as indicative of anisotropy in the Biscayne Aquifer. Geophysical methods included azimuthal resistivity measurements, electrical resistivity imaging (ERI) and ground penetrating radar (GPR) and were constrained with direct borehole information from nearby wells. The geophysical measurements suggest the presence of a zone of low electrical resistivity (from ERI) and low electromagnetic wave velocity (from GPR) below the water table at depths of 4-9 m that corresponds to the depth of solution conduits seen in digital borehole images. Azimuthal electrical measurements at the site reported coefficients of electrical anisotropy as high as 1.36 suggesting the presence of an area of high porosity (most likely comprising different types of porosity) oriented in the E-W direction. This study shows how integrated geophysical methods can help detect the presence of areas of enhanced porosity which may influence the direction of groundwater flow in a complex anisotropic and heterogeneous karst system like the Biscayne Aquifer.

Variable exchange between a stream and an aquifer in the Rio Grande Project Area

Science.gov (United States)

Sheng, Z.; Abudu, S.; Michelsen, A.; King, P.

2016-12-01

Both surface water and groundwater in the Rio Grande Project area in southern New Mexico and Far West Texas have been stressed by natural conditions such as droughts and human activities, including urban development and agricultural irrigation. In some area pumping stress in the aquifer becomes so great that it depletes the river flow especially during the irrigation season, typically from March through October. Therefore understanding such relationship between surface water and groundwater becomes more important in regional water resources planning and management. In this area, stream flows are highly regulated by the upstream reservoirs during the irrigation season and greatly influenced by return flows during non-irrigation season. During a drought additional groundwater pumping to supplement surface water shortage further complicates the surface water and groundwater interaction. In this paper the authors will use observation data and results of numerical models (MODFLOW) to characterize and quantify hydrological exchange fluxes between groundwater in the aquifers and surface water as well as impacts of groundwater pumping. The interaction shows a very interesting seasonal variation (irrigation vs. non-irrigation) as well as impact of a drought. Groundwater has been pumped for both municipal supplies and agricultural irrigation, which has imposed stresses toward both stream flows and aquifer storage. The results clearly show that historic groundwater pumping has caused some reaches of the river change from gaining stream to losing stream. Beyond the exchange between surface water and groundwater in the shallow aquifer, groundwater pumping in a deep aquifer could also enhance the exchanges between different aquifers through leaky confining layers. In the earlier history of pumping, pumping from the shallow aquifer is compensated by simple depletion of surface water, while deep aquifer tends to use the aquifer storage. With continued pumping, the cumulative

Modeling of fault activation and seismicity by injection directly into a fault zone associated with hydraulic fracturing of shale-gas reservoirs

Science.gov (United States)

LBNL, in consultation with the EPA, expanded upon a previous study by injecting directly into a 3D representation of a hypothetical fault zone located in the geologic units between the shale-gas reservoir and the drinking water aquifer.

Water management during climate change using aquifer storage and recovery of stormwater in a dunefield in western Saudi Arabia

International Nuclear Information System (INIS)

Lopez, O; Missimer, T M; Stenchikov, G

2014-01-01

An average of less than 50 mm yr −1 of rainfall occurs in the hyperarid region of central Western Saudi Arabia. Climate change is projected to create greater variation in rainfall accumulation with more intense rainfall and flood events and longer duration droughts. To manage climate change and variability in ephemeral stream basins, dams are being constructed across wadi channels to capture stormwater, but a large percentage of this stored water is lost to evaporation. A dam/reservoir system located in Wadi Al Murwani in Western Saudi Arabia was recently constructed and is expected to contain a maximum stored water volume of 150 million m 3 . A hydrologic assessment of a dunefield lying 45 km downstream was conducted to evaluate its potential use for aquifer storage and recovery of the reservoir water. A 110 m elevation difference between the base of the dam and the upper level of the dunefield occurs, allowing conveyance of the water from the reservoir to the dunefield storage site by gravity feed without pumping, making the recharge system extremely energy efficient. Aquifer storage and recovery coupled with dams would allow water management during extreme droughts and climate change and has widespread potential application in arid regions

Water management during climate change using aquifer storage and recovery of stormwater in a dunefield in western Saudi Arabia

KAUST Repository

Lopez Valencia, Oliver Miguel

2014-07-28

An average of less than 50 mm yr-1 of rainfall occurs in the hyperarid region of central Western Saudi Arabia. Climate change is projected to create greater variation in rainfall accumulation with more intense rainfall and flood events and longer duration droughts. To manage climate change and variability in ephemeral stream basins, dams are being constructed across wadi channels to capture stormwater, but a large percentage of this stored water is lost to evaporation. A dam/reservoir system located in Wadi Al Murwani in Western Saudi Arabia was recently constructed and is expected to contain a maximum stored water volume of 150 million m3. A hydrologic assessment of a dunefield lying 45 km downstream was conducted to evaluate its potential use for aquifer storage and recovery of the reservoir water. A 110 m elevation difference between the base of the dam and the upper level of the dunefield occurs, allowing conveyance of the water from the reservoir to the dunefield storage site by gravity feed without pumping, making the recharge system extremely energy efficient. Aquifer storage and recovery coupled with dams would allow water management during extreme droughts and climate change and has widespread potential application in arid regions. 2014 IOP Publishing Ltd.

Provision of Desalinated Irrigation Water by the Desalination of Groundwater within a Saline Aquifer

Directory of Open Access Journals (Sweden)

David D. J. Antia

2016-12-01

Full Text Available Irrigated land accounts for 70% of global water usage and 30% of global agricultural production. Forty percent of this water is derived from groundwater. Approximately 20%–30% of the groundwater sources are saline and 20%–50% of global irrigation water is salinized. Salinization reduces crop yields and the number of crop varieties which can be grown on an arable holding. Structured ZVI (zero valent iron, Fe0 pellets desalinate water by storing the removed ions as halite (NaCl within their porosity. This allows an “Aquifer Treatment Zone” to be created within an aquifer, (penetrated by a number of wells (containing ZVI pellets. This zone is used to supply partially desalinated water directly from a saline aquifer. A modeled reconfigured aquifer producing a continuous flow (e.g., 20 m3/day, 7300 m3/a of partially desalinated irrigation water is used to illustrate the impact of porosity, permeability, aquifer heterogeneity, abstraction rate, Aquifer Treatment Zone size, aquifer thickness, optional reinjection, leakage and flow by-pass on the product water salinity. This desalination approach has no operating costs (other than abstraction costs (and ZVI regeneration and may potentially be able to deliver a continuous flow of partially desalinated water (30%–80% NaCl reduction for $0.05–0.5/m3.

Hydrogeologic characterization of a fractured granitic rock aquifer, Raymond, California

Energy Technology Data Exchange (ETDEWEB)

Cohen, Andrew J.B. [Univ. of California, Berkeley, CA (United States)

1993-10-01

The hydrogeologic properties of a shallow, fractured granitic rock aquifer in the foothills of the Sierra Nevada, California were investigated via the analysis of borehole geophysical logs and pumping tests. The drawdowns produced during these tests are not indicative of any simple conceptual aquifer model, and borehole logs show that the granite is intensely fractured. These observations are suggestive of a complex fracture-flow geometry which is extremely difficult to decipher. However, through the measurement of orientations of individual subsurface fractures from acoustic televiewer logs, and correlation between particular fractures and electrical resistivity and thermal-pulse flowmeter logs, it was found that the aquifer is, in general, comprised of two subhorizontal and nearly parallel zones of unloading fractures. Downhole flowmeter measurements taken in several wells provide further evidence for the inferred dual-layer structure of the aquifer, as well as yield quantitative measures of the contribution of flow from each zone. Analysis of drawdowns in pumped wells reveals that there are zones of relatively high transmissivity immediately around them. It was found that these properties, as well as a nearby zone of lower transmissivity, can account for their observed drawdowns. A numerical model was constructed to test whether these major heterogeneities could also account for the drawdowns in observation wells. This stepwise analysis of both the geophysical and hydrological data resulted in the formulation of a conceptual model of the aquifer which is consistent with observations, and which can account for its behavior when subjected to pumping.

Application of advanced reservoir characterization, simulation and production optimization strategies to maximize recovery in slope and basin clastic reservoirs, West Texas (Delaware Basin). Annual report

Energy Technology Data Exchange (ETDEWEB)

Dutton, S.P.; Asquith, G.B.; Barton, M.D.; Cole, A.G.; Gogas, J.; Malik, M.A.; Clift, S.J.; Guzman, J.I.

1997-11-01

The objective of this project is to demonstrate that detailed reservoir characterization of slope and basin clastic reservoirs in sandstones of the Delaware Mountain Group in the Delaware Basin of West Texas and New Mexico is a cost-effective way to recover a higher percentage of the original oil in place through strategic placement of infill wells and geologically based field development. This project involves reservoir characterization of two Late Permian slope and basin clastic reservoirs in the Delaware Basin, West Texas, followed by a field demonstration in one of the fields. The fields being investigated are Geraldine Ford and Ford West fields in Reeves and Culberson Counties, Texas. Project objectives are divided into two major phases, reservoir characterization and implementation. The objectives of the reservoir characterization phase of the project were to provide a detailed understanding of the architecture and heterogeneity of the two fields, the Ford Geraldine unit and Ford West field. Reservoir characterization utilized 3-D seismic data, high-resolution sequence stratigraphy, subsurface field studies, outcrop characterization, and other techniques. Once reservoir characterized was completed, a pilot area of approximately 1 mi{sup 2} at the northern end of the Ford Geraldine unit was chosen for reservoir simulation. This report summarizes the results of the second year of reservoir characterization.

Water Supply Source Evaluation in Unmanaged Aquifer Recharge Zones: The Mezquital Valley (Mexico Case Study

Directory of Open Access Journals (Sweden)

Antonio Hernández-Espriú

2016-12-01

Full Text Available The Mezquital Valley (MV hosts the largest unmanaged aquifer recharge scheme in the world. The metropolitan area of Mexico City discharges ~60 m3/s of raw wastewater into the valley, a substantial share of which infiltrates into the regional aquifer. In this work, we aim to develop a comprehensive approach, adapted from oil and gas reservoir modeling frameworks, to assess water supply sources located downgradient from unmanaged aquifer recharge zones. The methodology is demonstrated through its application to the Mezquital Valley region. Geological, geoelectrical, petrophysical and hydraulic information is combined into a 3D subsurface model and used to evaluate downgradient supply sources. Although hydrogeochemical variables are yet to be assessed, outcomes suggest that the newly-found groundwater sources may provide a long-term solution for water supply. Piezometric analyses based on 25-year records suggest that the MV is close to steady-state conditions. Thus, unmanaged recharge seems to have been regulating the groundwater balance for the last decades. The transition from unmanaged to managed recharge is expected to provide benefits to the MV inhabitants. It will also be likely to generate new uncertainties in relation to aquifer dynamics and downgradient systems.

Three-dimensional multiphase effects in aquifer gas storage

Energy Technology Data Exchange (ETDEWEB)

Witherspoon, P.A.; Fuller, P.; Finsterle, S. [Lawrence Berkeley Laboratory, Berkeley, CA (United States)

1995-03-01

The underground storage of natural gas in the United States is one of the most widespread methods of storing energy in the United States. There are two main kinds of storage: (a) dry gas fields, and (b) aquifer storage fields. The storage of gas in dry gas fields involves the conversion of petroleum bearing reservoirs, usually after they have been depleted of any economic production, into a storage operation. An appropriate number of injection-withdrawal (I-W) wells are either drilled or converted from existing exploitation wells, and the storage operations begin by injecting gas to build up to some desired volume of gas in storage.

Numerical investigation of a joint approach to thermal energy storage and compressed air energy storage in aquifers

International Nuclear Information System (INIS)

Guo, Chaobin; Zhang, Keni; Pan, Lehua; Cai, Zuansi; Li, Cai; Li, Yi

2017-01-01

Highlights: •One wellbore-reservoir numerical model was built to study the impact of ATES on CAESA. •With high injection temperature, the joint of ATES can improve CAESA performance. •The considerable utilization of geothermal occurs only at the beginning of operations. •Combination of CAESA and ATES can be achieved in common aquifers. -- Abstract: Different from conventional compressed air energy storage (CAES) systems, the advanced adiabatic compressed air energy storage (AA-CAES) system can store the compression heat which can be used to reheat air during the electricity generation stage. Thus, AA-CAES system can achieve a higher energy storage efficiency. Similar to the AA-CAES system, a compressed air energy storage in aquifers (CAESA) system, which is integrated with an aquifer thermal energy storage (ATES) could possibly achieve the same objective. In order to investigate the impact of ATES on the performance of CAESA, different injection air temperature schemes are designed and analyzed by using numerical simulations. Key parameters relative to energy recovery efficiencies of the different injection schemes, such as pressure distribution and temperature variation within the aquifers as well as energy flow rate in the injection well, are also investigated in this study. The simulations show that, although different injection schemes have a similar overall energy recovery efficiency (∼97%) as well as a thermal energy recovery efficiency (∼79.2%), the higher injection air temperature has a higher energy storage capability. Our results show the total energy storage for the injection air temperature at 80 °C is about 10% greater than the base model scheme at 40 °C. Sensitivity analysis reveal that permeability of the reservoir boundary could have significant impact on the system performance. However, other hydrodynamic and thermodynamic properties, such as the storage reservoir permeability, thermal conductivity, rock grain specific heat and rock

AN ADVANCED FRACTURE CHARACTERIZATION AND WELL PATH NAVIGATION SYSTEM FOR EFFECTIVE RE-DEVELOPMENT AND ENHANCEMENT OF ULTIMATE RECOVERY FROM THE COMPLEX MONTEREY RESERVOIR OF SOUTH ELLWOOD FIELD, OFFSHORE CALIFORNIA

Energy Technology Data Exchange (ETDEWEB)

Steve Horner

2004-04-29

Venoco Inc, intends to re-develop the Monterey Formation, a Class III basin reservoir, at South Ellwood Field, Offshore Santa Barbara, California. Well productivity in this field varies significantly. Cumulative Monterey production for individual wells has ranged from 260 STB to 8,700,000 STB. Productivity is primarily affected by how well the well path connects with the local fracture system and the degree of aquifer support. Cumulative oil recovery to date is a small percentage of the original oil in place. To embark upon successful re-development and to optimize reservoir management, Venoco intends to investigate, map and characterize field fracture patterns and the reservoir conduit system. State of the art borehole imaging technologies including FMI, dipole sonic and cross-well seismic, interference tests and production logs will be employed to characterize fractures and micro faults. These data along with the existing database will be used for construction of a novel geologic model of the fracture network. Development of an innovative fracture network reservoir simulator is proposed to monitor and manage the aquifer's role in pressure maintenance and water production. The new fracture simulation model will be used for both planning optimal paths for new wells and improving ultimate recovery. In the second phase of this project, the model will be used for the design of a pilot program for downhole water re-injection into the aquifer simultaneously with oil production. Downhole water separation units attached to electric submersible pumps will be used to minimize surface fluid handling thereby improving recoveries per well and field economics while maintaining aquifer support. In cooperation with the DOE, results of the field studies as well as the new models developed and the fracture database will be shared with other operators. Numerous fields producing from the Monterey and analogous fractured reservoirs both onshore and offshore will benefit from the

Time scales of DNAPL migration in sandy aquifers examined via numerical simulation

Energy Technology Data Exchange (ETDEWEB)

Gerhard, J.I.; Pang, T.; Kueper, B.H. [University of Edinburgh, Edinburgh (United Kingdom). Inst. of Infrastructure & Environmental

2007-03-15

The time required for dense nonaqueous phase liquid (DNAPL) to cease migrating following release to the subsurface is a valuable component of a site conceptual model. This study uses numerical simulation to investigate the migration of six different DNAPLs in sandy aquifers. The most influential parameters governing migration cessation time are the density and viscosity of the DNAPL and the mean hydraulic conductivity of the aquifer. Releases of between 1 and 40 drums of chlorinated solvent DNAPLs, characterized by relatively high density and low viscosity, require on the order of months to a few years to cease migrating in a heterogeneous medium sand aquifer having an average hydraulic conductivity of 7.4 x 10{sup -3} cm/s. In contrast to this, the release of 20 drums of coal tar {rho}{sub D} = 1061 kg/m{sup 3}, {mu}{sub D} = 0.161 Pa(.)s) requires more than 100 years to cease migrating in the same aquifer. Altering the mean hydraulic conductivity of the aquifer results in a proportional change in cessation times. Parameters that exhibit relatively little influence on migration time scales are the DNAPL-water interfacial tension, release volume, source capillary pressure, mean aquifer porosity, and ambient ground water hydraulic gradient. This study also demonstrates that low-density DNAPLs (e.g., coal tar) give rise to greater amounts of lateral spreading and greater amounts of pooling on capillary barriers than high-density DNAPLs such as trichloroethylene or tetrachloroethylene.

Study on detailed geological modelling for fluvial sandstone reservoir in Daqing oil field

Energy Technology Data Exchange (ETDEWEB)

Zhao Hanqing; Fu Zhiguo; Lu Xiaoguang [Institute of Petroleum Exploration and Development, Daqing (China)

1997-08-01

Guided by the sedimentation theory and knowledge of modern and ancient fluvial deposition and utilizing the abundant information of sedimentary series, microfacies type and petrophysical parameters from well logging curves of close spaced thousands of wells located in a large area. A new method for establishing detailed sedimentation and permeability distribution models for fluvial reservoirs have been developed successfully. This study aimed at the geometry and internal architecture of sandbodies, in accordance to their hierarchical levels of heterogeneity and building up sedimentation and permeability distribution models of fluvial reservoirs, describing the reservoir heterogeneity on the light of the river sedimentary rules. The results and methods obtained in outcrop and modem sedimentation studies have successfully supported the study. Taking advantage of this method, the major producing layers (PI{sub 1-2}), which have been considered as heterogeneous and thick fluvial reservoirs extending widely in lateral are researched in detail. These layers are subdivided into single sedimentary units vertically and the microfacies are identified horizontally. Furthermore, a complex system is recognized according to their hierarchical levels from large to small, meander belt, single channel sandbody, meander scroll, point bar, and lateral accretion bodies of point bar. The achieved results improved the description of areal distribution of point bar sandbodies, provide an accurate and detailed framework model for establishing high resolution predicting model. By using geostatistic technique, it also plays an important role in searching for enriched zone of residual oil distribution.

Groundwater Origins and Circulation Patterns Based on Isotopes in Challapampa Aquifer, Bolivia

Directory of Open Access Journals (Sweden)

Etzar Gómez

2016-05-01

Full Text Available Aridity and seasonality of precipitation are characteristics of the highland region in Bolivia. Groundwater becomes an important and safe source of water when surficial bodies are intermittent and affected by natural and anthropogenic contamination. Decades of exploitation of the Challapampa aquifer, combined with lack of information required to understand the groundwater circulation, represent a challenge for reservoir management. This study analyzes isotopic compositions of deuterium and oxygen-18 in different stages in the hydrologic cycle to assess flow patterns in the aquifer, especially in the alluvial fan of River Paria, where records are more extensive in space and time. Interpretations are based on existing and new data. Some implications, such as the age of water, the evaporation effect in groundwater and some thermal intrusions are supported by stable isotopes, tritium, radiocarbon, and electrical conductivity records. New results confirm that modern precipitation over the mountains surrounding the study area is the most important origin of water for shallow aquifers until exploited depths, 100 m below surface. The origin of water in deeper depths, 400 m, seems related to infiltration at higher altitudes and longer residence times.

Application of Fe-Cu/Biochar System for Chlorobenzene Remediation of Groundwater in Inhomogeneous Aquifers

Directory of Open Access Journals (Sweden)

Xu Zhang

2017-12-01

Full Text Available Chlorobenzene (CB, as a typical Volatile Organic Contaminants (VOC, is toxic, highly persistent and easily migrates in water, posing a significant risk to human health and subsurface ecosystems. Therefore, exploring effective approaches to remediate groundwater contaminated by CB is essential. As an enhanced micro-electrolysis system for CB-contaminated groundwater remediation, this study attempted to couple the iron-copper bimetal with biochar. Two series of columns using sands with different grain diameters were used, consisting of iron, copper and biochar fillings as the permeable reactive barriers (PRBs, to simulate the remediation of CB-contaminated groundwater in homogeneous and heterogeneous aquifers. Regardless of the presence of homogeneous or heterogeneous porous media, the CB concentrations in the effluent from the PRB columns were significantly lower than the natural sandy columns, suggesting that the iron and copper powders coupled with biochar particles could have a significant removal effect compared to the natural sand porous media in the first columns. CB was transported relatively quickly in the heterogeneous porous media, likely due to the fact that the contaminant residence time is proportional to the infiltration velocities in the different types of porous media. The average effluent CB concentrations from the heterogeneous porous media were lower than those from homogeneous porous media. The heterogeneity retarded the vertical infiltration of CB, leading to its extended lateral distribution. During the treatment process, benzene and phenol were observed as the products of CB degradation. The ultimate CB removal efficiency was 61.4% and 68.1%, demonstrating that the simulated PRB system with the mixture of iron, copper and biochar was effective at removing CB from homogeneous and heterogeneous aquifers.

Software packages for simulating groundwater flow and the spreading of soluble and insoluble admixtures in aquifers

International Nuclear Information System (INIS)

Roshal, A.A.; Klein, I.S.; Svishchov, A.M.

1993-01-01

Software programs are described designed for solving hydrogeological and environmental problems related to the analysis and prediction of groundwater flow and the spreading of solutes and insolubles in the saturated zones. The software package GWFS (Ground Water Flow Simulation) allows for simulating steady-state and unsteady-state flow in confined, unconfined, and confined-unconfined multi-layer and quasi-3D isotropic and anisotropic aquifer systems. Considered are intra-layer sources and sinks, infiltration, inter-layer leakages, the interrelationships with surface reservoirs and streams, interrelationships with the drains, aquifer discharge to surface sources. The MTS (Mass Transport Simulation) package is designed for solving solute transport problems. Taken into account is convective transport, hydrodynamic dispersion and diffusion, linear equilibrium sorption. The method of characteristics is being implemented here using the ''particles-in-cells'' scheme in which the transport is modeled with the help of tracers. The software package OWFS (Oil-Water Flow Simulation) is designed for the simulation of hydrocarbon (oil-water) migration in aquifers

The typology of Irish hard-rock aquifers based on an integrated hydrogeological and geophysical approach

Science.gov (United States)

Comte, Jean-Christophe; Cassidy, Rachel; Nitsche, Janka; Ofterdinger, Ulrich; Pilatova, Katarina; Flynn, Raymond

2012-12-01

Groundwater flow in hard-rock aquifers is strongly controlled by the characteristics and distribution of structural heterogeneity. A methodology for catchment-scale characterisation is presented, based on the integration of complementary, multi-scale hydrogeological, geophysical and geological approaches. This was applied to three contrasting catchments underlain by metamorphic rocks in the northern parts of Ireland (Republic of Ireland and Northern Ireland, UK). Cross-validated surface and borehole geophysical investigations confirm the discontinuous overburden, lithological compartmentalisation of the bedrock and important spatial variations of the weathered bedrock profiles at macro-scale. Fracture analysis suggests that the recent (Alpine) tectonic fabric exerts strong control on the internal aquifer structure at meso-scale, which is likely to impact on the anisotropy of aquifer properties. The combination of the interpretation of depth-specific hydraulic-test data with the structural information provided by geophysical tests allows characterisation of the hydrodynamic properties of the identified aquifer units. Regionally, the distribution of hydraulic conductivities can be described by inverse power laws specific to the aquifer litho-type. Observed groundwater flow directions reflect this multi-scale structure. The proposed integrated approach applies widely available investigative tools to identify key dominant structures controlling groundwater flow, characterising the aquifer type for each catchment and resolving the spatial distribution of relevant aquifer units and associated hydrodynamic parameters.

High-resolution reservoir characterization by seismic inversion with geological constraints

NARCIS (Netherlands)

Tetyukhina, D.

2010-01-01

Fluvio-deltaic sedimentary systems are of great interest for explorationists because they can form prolific hydrocarbon plays. However, they are also among the most complex and heterogeneous ones encountered in the subsurface. Reservoirs in clinoform systems are difficult to characterize because

CO{sub 2} interfacial properties: application to multiphase flow at reservoir conditions; Proprietes interfaciales du CO{sub 2}: application aux ecoulements en milieu poreux en pression et temperature

Energy Technology Data Exchange (ETDEWEB)

Chalbaud, C

2007-07-15

In this work we deal with the interfacial properties of CO{sub 2} at reservoir conditions with a special interest on deep saline aquifers. Each chapter of this dissertation represents a different physical scale studied with different experimental devices and simulation tools. The results obtained in the first part of this study represent a complete data set of brine-CO{sub 2} interfacial tension at reservoir conditions. A semi-analytical equation is proposed in order to facilitate the work of reservoir engineers. The second deals with the interfacial properties at the pore scale using glass micro-models at different wettability conditions. This part shows the wetting behavior of CO{sub 2} on hydrophobic or oil-wet solid surfaces. A pore network model was used for the interpretation and exploitation of these results. The third part corresponds to two different experimental approaches at the core scale at different wettability conditions associated to a modelling at flue Darcy scale. This part is a significant contribution to the validation of COORES compositional reservoir simulator developed by IFP. It has also allow us to estimate multiphase properties, Pc and kr, for brine-CO{sub 2} systems at reservoir conditions. This study presents the necessary scales to model CO{sub 2} storage in deep saline aquifers. (author)

Key Factors for Determining Risk of Groundwater Impacts Due to Leakage from Geologic Carbon Sequestration Reservoirs

Energy Technology Data Exchange (ETDEWEB)

Carroll, Susan [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Keating, Elizabeth [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mansoor, Kayyum [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Dai, Zhenue [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sun, Yunwei [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Trainor-Guitton, Whitney [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Brown, Chris [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bacon, Diana [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2014-01-06

The National Risk Assessment Partnership (NRAP) is developing a science-based toolset for the analysis of potential impacts to groundwater chemistry from CO₂ injection (www.netldoe.gov/nrap). The toolset adopts a stochastic approach in which predictions address uncertainties in shallow underwater and leakage scenarios. It is derived from detailed physics and chemistry simulation results that are used to train more computationally efficient models,l referred to here as reduced-order models (ROMs), for each component system. In particular, these tools can be used to help regulators and operators understand the expected sizes and longevity of plumes in pH, TDS, and dissolved metals that could result from a leakage of brine and/or CO₂ from a storage reservoir into aquifers. This information can inform, for example, decisions on monitoring strategies that are both effective and efficient. We have used this approach to develop predictive reduced-order models for two common types of reservoirs, but the approach could be used to develop a model for a specific aquifer or other common types of aquifers. In this paper we describe potential impacts to groundwater quality due to CO₂ and brine leakage, discuss an approach to calculate thresholds under which "no impact" to groundwater occurs, describe the time scale for impact on groundwater, and discuss the probability of detecting a groundwater plume should leakage occur.

Obtaining Samples Representative of Contaminant Distribution in an Aquifer

International Nuclear Information System (INIS)

Schalla, Ronald; Spane, Frank A.; Narbutovskih, Susan M.; Conley, Scott F.; Webber, William D.

2002-01-01

Historically, groundwater samples collected from monitoring wells have been assumed to provide average indications of contaminant concentrations within the aquifer over the well-screen interval. In-well flow circulation, heterogeneity in the surrounding aquifer, and the sampling method utilized, however, can significantly impact the representativeness of samples as contaminant indicators of actual conditions within the surrounding aquifer. This paper identifies the need and approaches essential for providing cost-effective and technically meaningful groundwater-monitoring results. Proper design of the well screen interval is critical. An accurate understanding of ambient (non-pumping) flow conditions within the monitoring well is essential for determining the contaminant distribution within the aquifer. The ambient in-well flow velocity, flow direction and volumetric flux rate are key to this understanding. Not only do the ambient flow conditions need to be identified for preferential flow zones, but also the probable changes that will be imposed under dynamic conditions that occur during groundwater sampling. Once the in-well flow conditions are understood, effective sampling can be conducted to obtain representative samples for specific depth zones or zones of interest. The question of sample representativeness has become an important issue as waste minimization techniques such as low flow purging and sampling are implemented to combat the increasing cost of well purging and sampling at many hazardous waste sites. Several technical approaches (e.g., well tracer techniques and flowmeter surveys) can be used to determine in-well flow conditions, and these are discussed with respect to both their usefulness and limitations. Proper fluid extraction methods using minimal, (low) volume and no purge sampling methods that are used to obtain representative samples of aquifer conditions are presented

Geological modeling for methane hydrate reservoir characterization in the eastern Nankai Trough, offshore Japan

Science.gov (United States)

Tamaki, M.; Komatsu, Y.; Suzuki, K.; Takayama, T.; Fujii, T.

2012-12-01

The eastern Nankai trough, which is located offshore of central Japan, is considered as an attractive potential resource field of methane hydrates. Japan Oil, Gas and Metals National Corporation is planning to conduct a production test in early 2013 at the AT1 site in the north slope of Daini-Atsumi Knoll in the eastern Nankai Trough. The depositional environment of methane hydrate-bearing sediments around the production test site is a deep submarine-fan turbidite system, and it is considered that the reservoir properties should show lateral as well as vertical heterogeneity. Since the variations in the reservoir heterogeneity have an impact on the methane hydrate dissociation and gas production performance, precise geological models describing reservoir heterogeneity would be required for the evaluation of reservoir potentials. In preparation for the production test, 3 wells; two monitoring boreholes (AT1-MC and AT1-MT1) and a coring well (AT1-C), were newly acquired in 2012. In addition to a geotechnical hole drilling survey in 2011 (AT1-GT), totally log data from 2 wells and core data from 2 wells were obtained around the production test site. In this study, we conducted well correlations between AT1 and A1 wells drilled in 2003 and then, 3D geological models were updated including AT1 well data in order to refine hydrate reservoir characterization around the production test site. The results of the well correlations show that turbidite sand layers are characterized by good lateral continuity, and give significant information for the distribution morphology of sand-rich channel fills. We also reviewed previously conducted 3D geological models which consist of facies distributions and petrophysical properties distributions constructed from integration of 3D seismic data and a well data (A1 site) adopting a geostatistical approach. In order to test the practical validity of the previously generated models, cross-validation was conducted using AT1 well data. The

Multiple technologies applied to characterization of the porosity and permeability of the Biscayne aquifer, Florida

Science.gov (United States)

Cunningham, K.J.; Sukop, M.C.

2011-01-01

Research is needed to determine how seepage-control actions planned by the Comprehensive Everglades Restoration Plan (CERP) will affect recharge, groundwater flow, and discharge within the dual-porosity karstic Biscayne aquifer where it extends eastward from the Everglades to Biscayne Bay. A key issue is whether the plan can be accomplished without causing urban flooding in adjacent populated areas and diminishing coastal freshwater flow needed in the restoration of the ecologic systems. Predictive simulation of groundwater flow is a prudent approach to understanding hydrologic change and potential ecologic impacts. A fundamental problem to simulation of karst groundwater flow is how best to represent aquifer heterogeneity. Currently, U.S. Geological Survey (USGS) researchers and academic partners are applying multiple innovative technologies to characterize the spatial distribution of porosity and permeability within the Biscayne aquifer.

Effects of Heterogeneity and Uncertainties in Sources and Initial and Boundary Conditions on Spatiotemporal Variations of Groundwater Levels

Science.gov (United States)

Zhang, Y. K.; Liang, X.

2014-12-01

Effects of aquifer heterogeneity and uncertainties in source/sink, and initial and boundary conditions in a groundwater flow model on the spatiotemporal variations of groundwater level, h(x,t), were investigated. Analytical solutions for the variance and covariance of h(x, t) in an unconfined aquifer described by a linearized Boussinesq equation with a white noise source/sink and a random transmissivity field were derived. It was found that in a typical aquifer the error in h(x,t) in early time is mainly caused by the random initial condition and the error reduces as time goes to reach a constant error in later time. The duration during which the effect of the random initial condition is significant may last a few hundred days in most aquifers. The constant error in groundwater in later time is due to the combined effects of the uncertain source/sink and flux boundary: the closer to the flux boundary, the larger the error. The error caused by the uncertain head boundary is limited in a narrow zone near the boundary but it remains more or less constant over time. The effect of the heterogeneity is to increase the variation of groundwater level and the maximum effect occurs close to the constant head boundary because of the linear mean hydraulic gradient. The correlation of groundwater level decreases with temporal interval and spatial distance. In addition, the heterogeneity enhances the correlation of groundwater level, especially at larger time intervals and small spatial distances.

Groundwater potentiality mapping using geoelectrical-based aquifer hydraulic parameters: A GIS-based multi-criteria decision analysis modeling approach

Directory of Open Access Journals (Sweden)

Kehinde Anthony Mogaji Hwee San Lim

2017-01-01

Full Text Available This study conducted a robust analysis on acquired 2D resistivity imaging data and borehole pumping test records to optimize groundwater potentiality mapping in Perak province, Malaysia using derived aquifer hydraulic properties. The transverse resistance (TR parameter was determined from the interpreted 2D resistivity imaging data by applying the Dar-Zarrouk parameter equation. Linear regression and GIS techniques were used to regress the estimated values for TR parameters with the aquifer transmissivity values extracted from the geospatially produced BPT records-based aquifer transmissivity map to develop the aquifer transmissivity parameter predictive (ATPP model. The reliability evaluated ATPP model using the Theil inequality coefficient measurement approach was used to establish geoelectrical-based hydraulic parameters (GHP modeling equations for the modeling of transmissivity (Tr, hydraulic conductivity (K, storativity (St, and hydraulic diffusivity (D properties. The applied GHP modeling equation results to the delineated aquifer media was used to produce aquifer potential conditioning factor maps for Tr, K, St, and D. The maps were modeled to develop an aquifer potential mapping index (APMI model via applying the multi-criteria decision analysis-analytic hierarchy process principle. The area groundwater reservoir productivity potential model map produced based on the processed APMI model estimates in the GIS environment was found to be 71% accurate. This study establishes a good alternative approach to determine aquifer hydraulic parameters even in areas where pumping test information is unavailable using a cost effective geophysical data. The produced map can be explored for hydrological decision making.

Thermal regime of the deep carbonate reservoir of the Po Plain (Italy)

Science.gov (United States)

Pasquale, V.; Chiozzi, P.; Verdoya, M.

2012-04-01

Italy is one of the most important countries in the world with regard to high-medium enthalpy geothermal resources, a large part of which is already extracted at relatively low cost. High temperatures at shallow to medium depth occur within a wide belt, several hundred kilometre long, west of the Apennines mountain chain. This belt, affected by recent lithosphere extension, includes several geothermal fields, which are largely exploited for electricity generation. Between the Alps and Apennines ranges, the deeper aquifer, occurring in carbonate rocks of the Po Plain, can host medium enthalpy fluids, which are exploited for district heating. Such a general picture of the available geothermal resources has been well established through several geophysical investigations and drillings. Nevertheless, additional studies are necessary to evaluate future developments, especially with reference to the deep carbonate aquifer of the Po Plain. In this paper, we focus on the eastern sector of the plain and try to gain a better understanding of the thermal regime by using synergically geothermal methodologies and geological information. The analysis of the temperatures recorded to about 6 km depth in hydrocarbon wells supplies basic constraints to outline the thermal regime of the sedimentary basin and to investigate the occurrence and importance of hydrothermal processes in the carbonate layer. After correction for drilling disturbance, temperatures were analysed, together with geological information, through an inversion technique based on a laterally constant thermal gradient model. The inferred thermal gradient changes with depth; it is quite low within the carbonate layer, while is larger in the overlying, practically impermeable formations. As the thermal conductivity variation does not justify such a thermal gradient difference, the vertical change can be interpreted as due to convective processes occurring in the carbonate layer, acting as thermal reservoir. The

Groundwater vulnerability mapping in Guadalajara aquifers system (Western Mexico)

Science.gov (United States)

Rizo-Decelis, L. David; Marín, Ana I.; Andreo, Bartolomé

2016-04-01

Groundwater vulnerability mapping is a practical tool to implement strategies for land-use planning and sustainable socioeconomic development coherent with groundwater protection. The objective of vulnerability mapping is to identify the most vulnerable zones of catchment areas and to provide criteria for protecting the groundwater used for drinking water supply. The delineation of protection zones in fractured aquifers is a challenging task due to the heterogeneity and anisotropy of hydraulic conductivities, which makes difficult prediction of groundwater flow organization and flow velocities. Different methods of intrinsic groundwater vulnerability mapping were applied in the Atemajac-Toluquilla groundwater body, an aquifers system that covers around 1300 km2. The aquifer supplies the 30% of urban water resources of the metropolitan area of Guadalajara (Mexico), where over 4.6 million people reside. Study area is located in a complex neotectonic active volcanic region in the Santiago River Basin (Western Mexico), which influences the aquifer system underneath the city. Previous works have defined the flow dynamics and identified the origin of recharge. In addition, the mixture of fresh groundwater with hydrothermal and polluted waters have been estimated. Two main aquifers compose the multilayer system. The upper aquifer is unconfined and consists of sediments and pyroclastic materials. Recharge of this aquifer comes from rainwater and ascending vertical fluids from the lower aquifer. The lower aquifer consists of fractured basalts of Pliocene age. Formerly, the main water source has been the upper unit, which is a porous and unconsolidated unit, which acts as a semi-isotropic aquifer. Intense groundwater usage has resulted in lowering the water table in the upper aquifer. Therefore, the current groundwater extraction is carried out from the deeper aquifer and underlying bedrock units, where fracture flow predominates. Pollution indicators have been reported in

Reduced-Order Model for the Geochemical Impacts of Carbon Dioxide, Brine and Trace Metal Leakage into an Unconfined, Oxidizing Carbonate Aquifer, Version 2.1

Energy Technology Data Exchange (ETDEWEB)

Bacon, Diana H.

2013-03-31

The National Risk Assessment Partnership (NRAP) consists of 5 U.S DOE national laboratories collaborating to develop a framework for predicting the risks associated with carbon sequestration. The approach taken by NRAP is to divide the system into components, including injection target reservoirs, wellbores, natural pathways including faults and fractures, groundwater and the atmosphere. Next, develop a detailed, physics and chemistry-based model of each component. Using the results of the detailed models, develop efficient, simplified models, termed reduced order models (ROM) for each component. Finally, integrate the component ROMs into a system model that calculates risk profiles for the site. This report details the development of the Groundwater Geochemistry ROM for the Edwards Aquifer at PNNL. The Groundwater Geochemistry ROM for the Edwards Aquifer uses a Wellbore Leakage ROM developed at LANL as input. The detailed model, using the STOMP simulator, covers a 5x8 km area of the Edwards Aquifer near San Antonio, Texas. The model includes heterogeneous hydraulic properties, and equilibrium, kinetic and sorption reactions between groundwater, leaked CO2 gas, brine, and the aquifer carbonate and clay minerals. Latin Hypercube sampling was used to generate 1024 samples of input parameters. For each of these input samples, the STOMP simulator was used to predict the flux of CO2 to the atmosphere, and the volume, length and width of the aquifer where pH was less than the MCL standard, and TDS, arsenic, cadmium and lead exceeded MCL standards. In order to decouple the Wellbore Leakage ROM from the Groundwater Geochemistry ROM, the response surface was transformed to replace Wellbore Leakage ROM input parameters with instantaneous and cumulative CO2 and brine leakage rates. The most sensitive parameters proved to be the CO2 and brine leakage rates from the well, with equilibrium coefficients for calcite and dolomite, as well as the number of illite and kaolinite

Managed aquifer recharge through off-season irrigation in agricultural regions

Science.gov (United States)

Niswonger, Richard G.; Morway, Eric D.; Triana, Enrique; Huntington, Justin L.

2017-08-01

Options for increasing reservoir storage in developed regions are limited and prohibitively expensive. Projected increases in demand call for new long-term water storage to help sustain agriculture, municipalities, industry, and ecological services. Managed aquifer recharge (MAR) is becoming an integral component of water resources around the world. However, MAR faces challenges, including infrastructure costs, difficulty in enhancing recharge, water quality issues, and lack of available water supplies. Here we examine, through simulation modeling of a hypothetical agricultural subbasin in the western U.S., the potential of agricultural managed aquifer recharge (Ag-MAR) via canal seepage and off-season field irrigation. Weather phenomenon in many regions around the world exhibit decadal and other multiyear cycles of extreme precipitation. An ongoing challenge is to develop approaches to store greater amounts of water during these events. Simulations presented herein incorporate Ag-MAR programs and demonstrate that there is potential to enhance regional recharge by 7-13%, increase crop consumptive use by 9-12%, and increase natural vegetation consumption by 20-30%, where larger relative increases occur for lower aquifer hydraulic conductivity and higher specific yield values. Annual increases in groundwater levels were 7 m, and sustained levels following several years of drought were greater than 2 m. Results demonstrate that Ag-MAR has great potential to enhance long-term sustainability of water resources in agricultural basins.

Relationship of regional water quality to aquifer thermal energy storage

Energy Technology Data Exchange (ETDEWEB)

Allen, R.D.

1983-11-01

Ground-water quality and associated geologic characteristics may affect the feasibility of aquifer thermal energy storage (ATES) system development in any hydrologic region. This study sought to determine the relationship between ground-water quality parameters and the regional potential for ATES system development. Information was collected from available literature to identify chemical and physical mechanisms that could adversely affect an ATES system. Appropriate beneficiation techniques to counter these potential geochemical and lithologic problems were also identified through the literature search. Regional hydrology summaries and other sources were used in reviewing aquifers of 19 drainage regions in the US to determine generic geochemical characteristics for analysis. Numerical modeling techniques were used to perform geochemical analyses of water quality from 67 selected aquifers. Candidate water resources regions were then identified for exploration and development of ATES. This study identified six principal mechanisms by which ATES reservoir permeability may be impaired: (1) particulate plugging, (2) chemical precipitation, (3) liquid-solid reactions, (4) formation disaggregation, (5) oxidation reactions, and (6) biological activity. Specific proven countermeasures to reduce or eliminate these effects were found. Of the hydrologic regions reviewed, 10 were identified as having the characteristics necessary for ATES development: (1) Mid-Atlantic, (2) South-Atlantic Gulf, (3) Ohio, (4) Upper Mississippi, (5) Lower Mississippi, (6) Souris-Red-Rainy, (7) Missouri Basin, (8) Arkansas-White-Red, (9) Texas-Gulf, and (10) California.

Managed aquifer recharge through off-season irrigation in agricultural regions

Science.gov (United States)

Niswonger, Richard; Morway, Eric D.; Triana, Enrique; Huntington, Justin L.

2017-01-01

Options for increasing reservoir storage in developed regions are limited and prohibitively expensive. Projected increases in demand call for new long-term water storage to help sustain agriculture, municipalities, industry, and ecological services. Managed aquifer recharge (MAR) is becoming an integral component of water resources around the world. However, MAR faces challenges, including infrastructure costs, difficulty in enhancing recharge, water quality issues, and lack of available water supplies. Here we examine, through simulation modeling of a hypothetical agricultural subbasin in the western U.S., the potential of agricultural managed aquifer recharge (Ag-MAR) via canal seepage and off-season field irrigation. Weather phenomenon in many regions around the world exhibit decadal and other multiyear cycles of extreme precipitation. An ongoing challenge is to develop approaches to store greater amounts of water during these events. Simulations presented herein incorporate Ag-MAR programs and demonstrate that there is potential to enhance regional recharge by 7–13%, increase crop consumptive use by 9–12%, and increase natural vegetation consumption by 20–30%, where larger relative increases occur for lower aquifer hydraulic conductivity and higher specific yield values. Annual increases in groundwater levels were 7 m, and sustained levels following several years of drought were greater than 2 m. Results demonstrate that Ag-MAR has great potential to enhance long-term sustainability of water resources in agricultural basins.

Out of sight, but in their minds: Brazil and its neighbours work together to protect one of the world’s largest groundwater reservoirs

International Nuclear Information System (INIS)

Jawerth, Nicole

2015-01-01

Shrouded in mystery, the future of the largest groundwater reservoir in Latin America once left scientists, academics and politicians in Brazil, Argentina, Paraguay and Uruguay concerned about the fate of their major freshwater resource. Uncovering clues using nuclear techniques, Brazil and its neighbours are now well-acquainted with the Guarani Aquifer and can confidently expect that, with their new protection and sustainable use framework, water from the aquifer will continue to flow for at least another 200 years. Using isotope hydrology, a nuclear technique, the four countries analysed and assessed the aquifer to evaluate the age, origin and evolution of the groundwater, as well as its quality and the risk of contamination.

Full Waveform Inversion for Reservoir Characterization - A Synthetic Study

KAUST Repository

Zabihi Naeini, E.

2017-05-26

Most current reservoir-characterization workflows are based on classic amplitude-variation-with-offset (AVO) inversion techniques. Although these methods have generally served us well over the years, here we examine full-waveform inversion (FWI) as an alternative tool for higher-resolution reservoir characterization. An important step in developing reservoir-oriented FWI is the implementation of facies-based rock physics constraints adapted from the classic methods. We show that such constraints can be incorporated into FWI by adding appropriately designed regularization terms to the objective function. The advantages of the proposed algorithm are demonstrated on both isotropic and VTI (transversely isotropic with a vertical symmetry axis) models with pronounced lateral and vertical heterogeneity. The inversion results are explained using the theoretical radiation patterns produced by perturbations in the medium parameters.

Anionic co-contaminants and the biogeochemical evolution of aquifer heterogeneity. Final technical report

Energy Technology Data Exchange (ETDEWEB)

Fish, W.

1997-07-01

Adsorption heterogeneity of subsoils may depend on the sorbate and its concentration. Ligands in natural and contaminated subsoils may dissolve substantial metal oxides thereby altering the subsoil heterogeneity. We investigated these hypotheses on sands artificially and naturally coated with various amounts of metal oxides. The adsorbates Cu, oxalate, and mixtures of Cu and oxalate (Cu-Oxalate) were used as probes of the surface. For the concentration range studied, Binding Strength Analysis revealed that the naturally coated samples were heterogeneous at the microscale and the macroscale when oxalate was used as the probe of the surface. Cu revealed a smaller heterogeneity while Cu-Oxalate indicated an intermediate heterogeneity. Various elaborations of homogeneous-site Surface Complexation Models (SCM), calibrated to the surface protonation properties of goethite, modeled accurately the edges of oxalate, Cu, and mixtures of Cu and oxalate. The poorer fits for large concentrations was probably because of the site heterogeneity. The accuracy of SCMs was insensitive to the choice of surface protonation constants (pK{sub a}) and moderately sensitive to the choice of site density. The effective surface complexation constants (K{sup eff}) obtained from individual edges were somewhat different because of the concentration dependent heterogeneity. It was not always possible to use K{sup eff} values for one sorbate concentration to reproduce adsorption of other concentrations of the same sorbate. A modified version of the discrete pK{sub a} spectrum model closely reproduced the acid-base titration curve with two adsorption sites (four pK{sub a}`s). The adsorption of all concentrations of Cu, oxalate, and Cu-Oxalate was often reproduced with only one of those sites. The competition between the dissolved Al and the surface for the oxalate in solution was accurately reproduced with both sites. The dissolution of the oxide coating was often influenced by the pore velocity.

Structure and Filling Characteristics of Paleokarst Reservoirs in the Northern Tarim Basin, Revealed by Outcrop, Core and Borehole Images

Directory of Open Access Journals (Sweden)

Tian Fei

2017-06-01

Full Text Available The Ordovician paleokarst reservoirs in the Tahe oilfield, with burial depths of over 5300 m, experienced multiple phases of geologic processes and exhibit strong heterogeneity. Core testing can be used to analyse the characteristics of typical points at the centimetre scale, and seismic datasets can reveal the macroscopic outlines of reservoirs at the >10-m scale. However, neither method can identify caves, cave fills and fractures at the meter scale. Guided by outcrop investigations and calibrations based on core sample observations, this paper describes the interpretation of high longitudinal resolution borehole images, the identification of the characteristics of caves, cave fills (sedimentary, breccia and chemical fills and fractures in single wells, and the identification of structures and fill characteristics at the meter scale in the strongly heterogeneous paleokarst reservoirs. The paleogeomorphology, a major controlling factor in the distribution of paleokarst reservoirs, was also analysed. The results show that one well can penetrate multiple cave layers of various sizes and that the caves are filled with multiple types of fill. The paleogeomorphology can be divided into highlands, slopes and depressions, which controlled the structure and fill characteristics of the paleokarst reservoirs. The results of this study can provide fundamental meter-scale datasets for interpreting detailed geologic features of deeply buried paleocaves, can be used to connect core- and seismic-scale interpretations, and can provide support for the recognition and development of these strongly heterogeneous reservoirs.

Modelling studies for influence factors of gas bubble in compressed air energy storage in aquifers

International Nuclear Information System (INIS)

Guo, Chaobin; Zhang, Keni; Li, Cai; Wang, Xiaoyu

2016-01-01

CAES (Compressed air energy storage) is credited with its potential ability for large-scale energy storage. Generally, it is more convenient using deep aquifers than employing underground caverns for energy storage, because of extensive presence of aquifers. During the first stage in a typical process of CAESA (compressed air energy storage in aquifers), a large amount of compressed air is injected into the target aquifer to develop an initial space (a gas bubble) for energy storage. In this study, numerical simulations were conducted to investigate the influence of aquifer's permeability, geological structure and operation parameters on the formation of gas bubble and the sustainability for the later cycling operation. The SCT (system cycle times) was designed as a parameter to evaluate the reservoir performance and the effect of operation parameters. Simulation results for pressure and gas saturation results of basic model confirm the feasibility of compressed air energy storage in aquifers. The results of different permeability cases show that, for a certain scale of CAESA system, there is an optimum permeability range for a candidate aquifer. An aquifer within this permeability range will not only satisfy the injectivity requirement but also have the best energy efficiency. Structural impact analysis indicates that the anticline structure has the best performance to hold the bubble under the same daily cycling schedule with the same initial injected air mass. In addition, our results indicate that the SCT shows a logarithmic growth as the injected air mass increase. During the formation of gas bubble, compressed air should be injected into aquifers with moderate rate and the injection can be done in several stages with different injection rate to avoid onset pressure. - Highlights: • Impact of permeability, geological structure, operation parameters was investigated. • With certain air production rate, an optimum permeability exists for performance. �

Impact of lateral flow on the transition from connected to disconnected stream-aquifer systems

Science.gov (United States)

Xian, Yang; Jin, Menggui; Liu, Yanfeng; Si, Aonan

2017-05-01

Understanding the mechanisms by which stream water infiltrates through streambeds to recharge groundwater systems is essential to sustainable management of scarce water resources in arid and semi-arid areas. An inverted water table (IWT) can develop under a stream in response to the desaturation between the stream and underlying aquifer as the system changes from a connected to disconnected status. However, previous studies have suggested that the IWT can only occur at the bottom of a low permeability streambed in which only the vertical flow between the stream and groundwater during disconnection was assumed. In the present study, numerical simulations revealed that the lateral flow induced by capillarity or heterogeneity also plays an essential role on interactions between streams and aquifers. Three pathways were identified for the transition from connection to disconnection in homogenous systems; notably, the lowest point of an IWT can develop not only at the bottom of the streambed but also within the streambed or the aquifer in response to the initial desaturation at, above, or below the interface between the streambed and aquifer (IBSA), respectively. A sensitivity analysis indicated that in wide streams, the lowest point of an IWT only occurs at the bottom of the streambed; however, for a stream half width of 1 m above a 6 m thick sandy loam streambed, the lowest point occurs in the streambed as stream depth is less than 0.5 m. This critical stream depth increases with streambed thickness and decreases with stream width. Thus, in narrow streams the lowest point can also develop in a thick streambed under a shallow stream. In narrow streams, the lowest point also forms in the aquifer if the ratio of the hydraulic conductivity of the streambed to that of the aquifer is greater than the ratio of the streambed thickness to the sum of the stream depth and the streambed thickness; correspondingly, the streambed is thin but relatively permeable and the stream is

Sequestration of carbon in saline aquifers - mathematical and numerical analysis

Energy Technology Data Exchange (ETDEWEB)

Nordbotten, Jan Martin

2004-01-01

The work in this thesis focuses equally on two main topics. The set of these subjects deals with development of criteria for monotonicity of control volume methods. These methods are important and frequently used for solving the pressure equation arising in porous media flow. First we consider homogeneous parallelogram grids, and subsequently general logical Cartesian grids in heterogeneous media. This subject is concluded by the development of a new class of Multi Point Flux Approximation methods, motivated by the monotonicity results obtained. The second topic of this thesis is the development of analytical and semi- analytical solutions to the problem of leakage through abandoned wells. More specially, we look at a set of aquifers, separated by impermeable layers (aquicludes), where injection of water or CO{sub 2} takes place in some or all the aquifers. The aquifers and aquicludes are frequently penetrated by abandoned wells from oil exploration, and our problem consists of finding solutions to flow and leakage through these wells. The goal is to obtain expressions for leakage rates that may be evaluated quickly enough such that Monte Carlo realizations over statistical distributions of properties for abandoned wells can be performed. (author)

Putting integrated reservoir characterization into practice - in house training

Energy Technology Data Exchange (ETDEWEB)

Wright, F.M. Jr.; Best, D.A.; Clarke, R.T. [Mobile Exploration and Producing Technical Center, Dallas, TX (United States)

1997-08-01

The need for even more efficient reservoir characterization and management has forced a change in the way Mobil Oil provides technical support to its production operations. We`ve learned that to be successful, a good understanding of the reservoir is essential. This includes an understanding of the technical and business significance of reservoir heterogeneities at different stages of field development. A multi-disciplinary understanding of the business of integrated reservoir characterization is essential and to facilitate this understanding, Mobil has developed a highly successful {open_quotes}Reservoir Characterization Field Seminar{close_quotes}. Through specific team based case studies that incorporate outcrop examples and data the program provides participants the opportunity to explore historic and alternative approaches to reservoir description, characterization and management. We explore appropriate levels and timing of data gathering, technology applications, risk assessment and management practices at different stages of field development. The case studies presented throughout the course are a unique element of the program which combine real life and hypothetical problem sets that explore how different technical disciplines interact, the approaches to a problem solving they use, the assumptions and uncertainties contained in their contributions and the impact those conclusions may have on other disciplines involved in the overall reservoir management process. The team building aspect of the course was an added bonus.

Vertical small scale variations of sorption and mineralization of three herbicides in subsurface limestone and sandy aquifer

DEFF Research Database (Denmark)

Janniche, Gry Sander; Mouvet, C.; Albrechtsen, Hans-Jørgen

2011-01-01

, France. From two intact core drills, four heterogenic limestone sections were collected from 4.50-26.40 m below surface (mbs) and divided into 12 sub-samples of 8-25 cm length, and one sandy aquifer section from 19.20-19.53 m depth divided into 7 sub-samples of 4-5 cm length. In the sandy aquifer section...... showed that a 30 cm active layer with the measured sorption and mineralization values hardly impacted the fate of the investigated herbicides, whereas a total thickness of layers of 1 m would substantially increase natural attenuation....

Characterising aquifer treatment for pathogens in managed aquifer recharge.

Science.gov (United States)

Page, D; Dillon, P; Toze, S; Sidhu, J P S

2010-01-01

In this study the value of subsurface treatment of urban stormwater during Aquifer Storage Transfer Recovery (ASTR) is characterised using quantitative microbial risk assessment (QMRA) methodology. The ASTR project utilizes a multi-barrier treatment train to treat urban stormwater but to date the role of the aquifer has not been quantified. In this study it was estimated that the aquifer barrier provided 1.4, 2.6, >6.0 log(10) removals for rotavirus, Cryptosporidium and Campylobacter respectively based on pathogen diffusion chamber results. The aquifer treatment barrier was found to vary in importance vis-à-vis the pre-treatment via a constructed wetland and potential post-treatment options of UV-disinfection and chlorination for the reference pathogens. The risk assessment demonstrated that the human health risk associated with potable reuse of stormwater can be mitigated (disability adjusted life years, DALYs aquifer is integrated with suitable post treatment options into a treatment train to attenuate pathogens and protect human health.

A Statistical Graphical Model of the California Reservoir System

Science.gov (United States)

Taeb, A.; Reager, J. T.; Turmon, M.; Chandrasekaran, V.

2017-11-01

The recent California drought has highlighted the potential vulnerability of the state's water management infrastructure to multiyear dry intervals. Due to the high complexity of the network, dynamic storage changes in California reservoirs on a state-wide scale have previously been difficult to model using either traditional statistical or physical approaches. Indeed, although there is a significant line of research on exploring models for single (or a small number of) reservoirs, these approaches are not amenable to a system-wide modeling of the California reservoir network due to the spatial and hydrological heterogeneities of the system. In this work, we develop a state-wide statistical graphical model to characterize the dependencies among a collection of 55 major California reservoirs across the state; this model is defined with respect to a graph in which the nodes index reservoirs and the edges specify the relationships or dependencies between reservoirs. We obtain and validate this model in a data-driven manner based on reservoir volumes over the period 2003-2016. A key feature of our framework is a quantification of the effects of external phenomena that influence the entire reservoir network. We further characterize the degree to which physical factors (e.g., state-wide Palmer Drought Severity Index (PDSI), average temperature, snow pack) and economic factors (e.g., consumer price index, number of agricultural workers) explain these external influences. As a consequence of this analysis, we obtain a system-wide health diagnosis of the reservoir network as a function of PDSI.

The Guarani Aquifer System: estimation of recharge along the Uruguay-Brazil border

Science.gov (United States)

Gómez, Andrea A.; Rodríguez, Leticia B.; Vives, Luis S.

2010-11-01

The cities of Rivera and Santana do Livramento are located on the outcropping area of the sandstone Guarani Aquifer on the Brazil-Uruguay border, where the aquifer is being increasingly exploited. Therefore, recharge estimates are needed to address sustainability. First, a conceptual model of the area was developed. A multilayer, heterogeneous and anisotropic groundwater-flow model was built to validate the conceptual model and to estimate recharge. A field campaign was conducted to collect water samples and monitor water levels used for model calibration. Field data revealed that there exists vertical gradients between confining basalts and underlying sandstones, suggesting basalts could indirectly recharge sandstone in fractured areas. Simulated downward flow between them was a small amount within the global water budget. Calibrated recharge rates over basalts and over outcropping sandstones were 1.3 and 8.1% of mean annual precipitation, respectively. A big portion of sandstone recharge would be drained by streams. The application of a water balance yielded a recharge of 8.5% of average annual precipitation. The numerical model and the water balance yielded similar recharge values consistent with determinations from previous authors in the area and other regions of the aquifer, providing an upper bound for recharge in this transboundary aquifer.

Alluvial Aquifer

Data.gov (United States)

Kansas Data Access and Support Center — This coverage shows the extents of the alluvial aquifers in Kansas. The alluvial aquifers consist of unconsolidated Quaternary alluvium and contiguous terrace...

Hydrogeology and results of aquifer tests in the vicinity of a hazardous-waste disposal site near Byron, Illinois

Science.gov (United States)

Kay, Robert T.; Olson, David N.; Ryan, Barbara J.

1989-01-01

The U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, conducted an investigation of a Superfund Site near Byron, Illinois. The purpose of the investigation was to determine the hydrogeologic properties of the Galena-Platteville and St. Peter aquifers, the primary water-supply aquifers for domestic supply in the area. The Galena and Platteville Groups and older St. Peter Sandstone are separated by the Harmony Hill Shale Member of the Glenwood Formation. The Harmony Hill Shale Member is a semiconfining unit. Groundwater flow in the study area is from the site northwestward to the Rock River. Movement of groundwater in the dolomites is mainly through joints, fractures, and solution openings. Analysis of the Galena-Platteville aquifer-test data indicates that the calculated aquifer transmissivity ranges from 490 to 670 sq ft/day, and the calculated specific yield ranges from 0.017 to 0.140. Aquifer test data also indicate that the Galena-Platteville aquifer is heterogeneous and anisotropic. Analysis of the St. Peter aquifer-test data indicates that the calculated transmissivity of the aquifer ranges from 1,200 to 1 ,305 sq ft/day, storativity ranges from 0.000528 to 0.00128, horizontal hydraulic conductivity ranges from 2.9 to 3.1 ft/day, and leakage through the Harmony Hill Shale Member ranges from .000123 to .000217 ft/day/ft. (USGS)

Climate Change Adaptation in a Mediterranean Semi-Arid Catchment: Testing Managed Aquifer Recharge and Increased Surface Reservoir Capacity

Directory of Open Access Journals (Sweden)

Nicolas Guyennon

2017-09-01

Full Text Available Among different uses of freshwater, irrigation is the most impacting groundwater resource, leading to water table depletion and possible seawater intrusion. The unbalance between the availability of water resources and demand is currently exacerbated and could become worse in the near future in accordance with climate change observations and scenarios provided by Intergovernmental Panel on Climate Change (IPCC. In this context, Increasing Maximum Capacity of the surface reservoir (IMC and Managed Aquifer Recharge (MAR are adaptation measures that have the potential to enhance water supply systems resiliency. In this paper, a multiple-users and multiple-resources-Water Supply System (WSS model is implemented to evaluate the effectiveness of these two adaptation strategies in a context of overexploited groundwater under the RCP 4.5 and the RCP 8.5 IPCC scenarios. The presented a case study that is located in the Puglia, a semi-arid region of South Italy characterized by a conspicuous water demand for irrigation. We observed that, although no significant long-term trend affects the proposed precipitation scenarios, the expected temperature increase highly impacts the WSS resources due to the associated increase of water demand for irrigation purposes. Under the RCP 4.5 the MAR scenario results are more effective than the IMC during long term wet periods (typically 5 years and successfully compensates the impact on the groundwater resources. Differently, under RCP 8.5, due to more persistent dry periods, both adaptation scenarios fail and groundwater resource become exposed to massive sea water intrusion during the second half of the century. We conclude that the MAR scenario is a suitable adaptation strategy to face the expected future changes in climate, although mitigation actions to reduce green-house gases are strongly required.

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.

Seasonal Deep Aquifer Thermal Energy Storage in the Gassum Sandstone Formation

DEFF Research Database (Denmark)

Holmslykke, H.D.H.; Kjøller, C.; Fabricius, Ida Lykke

Seasonal storage of excess heat in hot deep aquifers is considered to optimise the usage of commonly available energy sources. The potential chemical reactions caused by heating the Gassum Sandstone Formation to up to 150°C is investigated by core flooding experiments combined with petrographic...... analysis and geochemical modelling. Synthetic formation water is injected into two sets of Gassum Formation samples at 25°C, 50°C (reservoir temperature), 100°C and 150°C with a velocity of 0.05 PV/hr and 0.1 PV/hr, respectively. A significant increase in the aqueous concentration of silicium and iron...

Heat tracer test in an alluvial aquifer: Field experiment and inverse modelling

Science.gov (United States)

Klepikova, Maria; Wildemeersch, Samuel; Hermans, Thomas; Jamin, Pierre; Orban, Philippe; Nguyen, Frédéric; Brouyère, Serge; Dassargues, Alain

2016-09-01

Using heat as an active tracer for aquifer characterization is a topic of increasing interest. In this study, we investigate the potential of using heat tracer tests for characterization of a shallow alluvial aquifer. A thermal tracer test was conducted in the alluvial aquifer of the Meuse River, Belgium. The tracing experiment consisted in simultaneously injecting heated water and a dye tracer in an injection well and monitoring the evolution of groundwater temperature and tracer concentration in the pumping well and in measurement intervals. To get insights in the 3D characteristics of the heat transport mechanisms, temperature data from a large number of observation wells closely spaced along three transects were used. Temperature breakthrough curves in observation wells are contrasted with what would be expected in an ideal layered aquifer. They reveal strongly unequal lateral and vertical components of the transport mechanisms. The observed complex behavior of the heat plume is explained by the groundwater flow gradient on the site and heterogeneities in the hydraulic conductivity field. Moreover, due to high injection temperatures during the field experiment a temperature-induced fluid density effect on heat transport occurred. By using a flow and heat transport numerical model with variable density coupled with a pilot point approach for inversion of the hydraulic conductivity field, the main preferential flow paths were delineated. The successful application of a field heat tracer test at this site suggests that heat tracer tests is a promising approach to image hydraulic conductivity field. This methodology could be applied in aquifer thermal energy storage (ATES) projects for assessing future efficiency that is strongly linked to the hydraulic conductivity variability in the considered aquifer.

Application of Advanced Reservoir Characterization, Simulation, and Production Optimization Strategies to Maximize Recovery in Slope and Basin Clastic Reservoirs, West Texas (Delaware Basin)

International Nuclear Information System (INIS)

Dutton, Shirley

1999-01-01

The objective of this Class 3 project was demonstrate that detailed reservoir characterization of slope and basin clastic reservoirs in sandstones of the Delaware Mountain Group in the Delaware Basin of West Texas and New Mexico is a cost effective way to recover a higher percentage of the original oil in place through strategic placement of infill wells and geologically based field development. Project objectives are divided into two main phases. The original objectives of the reservoir-characterization phase of the project were (1) to provide a detailed understanding of the architecture and heterogeneity of two representative fields of the Delaware Mountain Group, Geraldine Ford and Ford West, which produce from the Bell Canyon and Cherry Canyon Formations, respectively, (2) to chose a demonstration area in one of the fields, and (3) to simulate a CO 2 flood in the demonstration area

INTEGRATED GEOLOGIC-ENGINEERING MODEL FOR REEF AND CARBONATE SHOAL RESERVOIRS ASSOCIATED WITH PALEOHIGHS: UPPER JURASSIC SMACKOVER FORMATION, NORTHEASTERN GULF OF MEXICO

Energy Technology Data Exchange (ETDEWEB)

Ernest A. Mancini

2001-09-14

The University of Alabama in cooperation with Texas A&M University, McGill University, Longleaf Energy Group, Strago Petroleum Corporation, and Paramount Petroleum Company are undertaking an integrated, interdisciplinary geoscientific and engineering research project. The project is designed to characterize and model reservoir architecture, pore systems and rock-fluid interactions at the pore to field scale in Upper Jurassic Smackover reef and carbonate shoal reservoirs associated with varying degrees of relief on pre-Mesozoic basement paleohighs in the northeastern Gulf of Mexico. The project effort includes the prediction of fluid flow in carbonate reservoirs through reservoir simulation modeling which utilizes geologic reservoir characterization and modeling and the prediction of carbonate reservoir architecture, heterogeneity and quality through seismic imaging. The primary objective of the project is to increase the profitability, producibility and efficiency of recovery of oil from existing and undiscovered Upper Jurassic fields characterized by reef and carbonate shoals associated with pre-Mesozoic basement paleohighs. The principal research effort for Year 1 of the project has been reservoir description and characterization. This effort has included four tasks: (1) geoscientific reservoir characterization, (2) the study of rock-fluid interactions, (3) petrophysical and engineering characterization and (4) data integration. This work was scheduled for completion in Year 1. Overall, the project work is on schedule. Geoscientific reservoir characterization is essentially completed. The architecture, porosity types and heterogeneity of the reef and shoal reservoirs at Appleton and Vocation Fields have been characterized using geological and geophysical data. The study of rock-fluid interactions has been initiated. Observations regarding the diagenetic processes influencing pore system development and heterogeneity in these reef and shoal reservoirs have been

Chemical and microbiological monitoring of a sole-source aquifer intended for artificial recharge, Nassau County, New York

Science.gov (United States)

Katz, Brian G.; Mallard, Gail E.

1980-01-01

In late 1980, approximately 4 million gallons per day of highly treated wastewater will be used to recharge the groundwater reservoir in central Nassau County through a system of 10 recharge basins and 5 shallow injection wells. To evaluate the impact of large-scale recharge with reclaimed water on groundwater quality, the U.S. Geological Survey has collected hydrologic and water-quality data from a 1-square-mile area around the recharge site to provide a basis for future comparison. Extensive chemical and microbiological analyses are being made on samples from 48 wells screened in the upper glacial (water-table) aquifer and the upper part of the underlying Magothy (public-supply) aquifer. Preliminary results indicate that water from the upper glacial aquifer contains significant concentrations of nitrate and low-molecular-weight chlorinated hydrocarbons and detectable concentrations of organochlorine insecticides and polychlorinated biphenyls. At present, no fecal contamination is evident in either aquifer in the area studied. In the few samples containing fecal indicator bacteria, the numbers were low. Nonpoint sources provide significant loads of organic and inorganic compounds; major sources include cesspool and septic-tank effluent, cesspool and septic-tank cleaners and other over-the-counter domestic organic solvents, fertilizers, insecticides for termite and other pest control, and stormwater runoff to recharge basins. The water-table aquifer is composed mainly of stratified, well-sorted sand and gravel and, as a result, is highly permeable. In the 1-square-mile area studied, some contaminants seem to have traveled 200 feet downward to the bottom of the water-table aquifer and into the upper part of the public-supply aquifer. (USGS)

Influence of initial heterogeneities and recharge limitations on the evolution of aperture distributions in carbonate aquifers

Directory of Open Access Journals (Sweden)

B. Hubinger

2011-12-01

Full Text Available Karst aquifers evolve where the dissolution of soluble rocks causes the enlargement of discrete pathways along fractures or bedding planes, thus creating highly conductive solution conduits. To identify general interrelations between hydrogeological conditions and the properties of the evolving conduit systems the aperture-size frequency distributions resulting from generic models of conduit evolution are analysed. For this purpose, a process-based numerical model coupling flow and rock dissolution is employed. Initial protoconduits are represented by tubes with log-normally distributed aperture sizes with a mean μ₀ = 0.5 mm for the logarithm of the diameters. Apertures are spatially uncorrelated and widen up to the metre range due to dissolution by chemically aggressive waters. Several examples of conduit development are examined focussing on influences of the initial heterogeneity and the available amount of recharge. If the available recharge is sufficiently high the evolving conduits compete for flow and those with large apertures and high hydraulic gradients attract more and more water. As a consequence, the positive feedback between increasing flow and dissolution causes the breakthrough of a conduit pathway connecting the recharge and discharge sides of the modelling domain. Under these competitive flow conditions dynamically stable bimodal aperture distributions are found to evolve, i.e. a certain percentage of tubes continues to be enlarged while the remaining tubes stay small-sized. The percentage of strongly widened tubes is found to be independent of the breakthrough time and decreases with increasing heterogeneity of the initial apertures and decreasing amount of available water. If the competition for flow is suppressed because the availability of water is strongly limited breakthrough of a conduit pathway is inhibited and the conduit pathways widen very slowly. The resulting aperture distributions are found to be

Use of sinkhole and specific capacity distributions to assess vertical gradients in a karst aquifer

Science.gov (United States)

McCoy, K.J.; Kozar, M.D.

2008-01-01

The carbonate-rock aquifer in the Great Valley, West Virginia, USA, was evaluated using a database of 687 sinkholes and 350 specific capacity tests to assess structural, lithologic, and topographic influences on the groundwater flow system. The enhanced permeability of the aquifer is characterized in part by the many sinkholes, springs, and solutionally enlarged fractures throughout the valley. Yet, vertical components of subsurface flow in this highly heterogeneous aquifer are currently not well understood. To address this problem, this study examines the apparent relation between geologic features of the aquifer and two spatial indices of enhanced permeability attributed to aquifer karstification: (1) the distribution of sinkholes and (2) the occurrence of wells with relatively high specific capacity. Statistical results indicate that sinkholes (funnel and collapse) occur primarily along cleavage and bedding planes parallel to subparallel to strike where lateral or downward vertical gradients are highest. Conversely, high specific capacity values are common along prominent joints perpendicular or oblique to strike. The similarity of the latter distribution to that of springs suggests these fractures are areas of upward-convergent flow. These differences between sinkhole and high specific capacity distributions suggest vertical flow components are primarily controlled by the orientation of geologic structure and associated subsurface fracturing. ?? 2007 Springer-Verlag.

Salting it away : Saskatchewan's Petroleum Technology Research Centre is leading the study of storing CO{sub 2} in saline aquifers

Energy Technology Data Exchange (ETDEWEB)

Collison, M.

2008-10-15

This paper discussed the 5-year Aquistore project that is being conducted to assess the feasibility of continuously injecting carbon dioxide (CO{sub 2}) into saline aquifers. Conducted by the Petroleum Technology Research Centre (PTRC), the aim of the project is to develop the monitoring technologies needed to prove that the CO{sub 2} can be safely and permanently stored. The $100 million dollar project will also develop technologies needed to build the necessary infrastructure for transporting the CO{sub 2} to the aquifers. Saline aquifers contain more than 10 times the capacity of depleted oil reservoirs. It is estimated that saline aquifers in the Western Canadian Sedimentary Basin (WCSB) contain enough capacity to absorb all reported emissions in Alberta and Saskatchewan every year for the next 1000 years. CO{sub 2} injected into the aquifers will become a supercritical fluid as a result of pressure and temperature forces within the aquifer and will subsequently mineralize and remain there permanently. A dedicated pipeline will transport CO{sub 2} from a refinery in Regina to the aquifer. The project is being funded by Sustainable Development Technology Canada (SDTC), an agency whose mandate is to accelerate the entry of promising energy conservation technologies into the Canadian marketplace. It is hoped that the project will develop saline storage technologies that can be used to promote carbon sequestration in Canada. 5 figs.

A two-phase model of aquifer heterogeneity

International Nuclear Information System (INIS)

Moltyaner, G.L.

1994-11-01

A two-phase model of a fluid-saturated geologic medium is developed with groundwater velocity (rather than the hydraulic conductivity) as the primary model parameter. The model describes the groundwater flow, contaminant transport processes, and geologic medium structure at the local-scale of a continuum representation and relates structure to processes quantitatively. In this model, the heterogeneity of a geologic medium is characterized either in terms of the spatial variability in the bulk (local-scale) fluid density and sediment density, or in terms of variability in the local-scale porosity and effective grain diameter. The local-scale continuity equations resulting from these properties are derived for both phases. The effective grain diameter is employed to quantify the geologic structure. Velocity is employed to quantify the transport process. Since structure controls process, a high correlation is observed between the effective grain diameter and velocity. The observed correlation leads to a new formulation of Darcy's law without invoking the concept of a fictitious (Darcy's) velocity. The local-scale groundwater flow equation is developed on the basis of the new formulation. (author). 16 refs., 4 figs

Origins and processes of groundwater salinization in the urban coastal aquifers of Recife (Pernambuco, Brazil): A multi-isotope approach

International Nuclear Information System (INIS)

Cary, Lise; Petelet-Giraud, Emmanuelle; Bertrand, Guillaume; Kloppmann, Wolfram; Aquilina, Luc; Martins, Veridiana; Hirata, Ricardo; Montenegro, Suzana; Pauwels, Hélène; Chatton, Eliot; Franzen, Melissa; Aurouet, Axel; Lasseur, Eric; Picot, Géraldine; Guerrot, Catherine; Fléhoc, Christine

2015-01-01

In the coastal multilayer aquifer system of a highly urbanized southern city (Recife, Brazil), where groundwaters are affected by salinization, a multi-isotope approach (Sr, B, O, H) was used to investigate the sources and processes of salinization. The high diversity of the geological bodies, built since the Atlantic opening during the Cretaceous, highly constrains the heterogeneity of the groundwater chemistry, e.g. Sr isotope ratios, and needs to be integrated to explain the salinization processes and groundwater pathways. A paleoseawater intrusion, most probably the 120 ky B.P. Pleistocene marine transgression, and cationic exchange are clearly evidenced in the most salinized parts of the Cabo and Beberibe aquifers. All 87 Sr/ 86 Sr values are above the past and present-day seawater signatures, meaning that the Sr isotopic signature is altered due to additional Sr inputs from dilution with different freshwaters, and water–rock interactions. Only the Cabo aquifer presents a well-delimitated area of Na-HCO 3 water typical of a freshening process. The two deep aquifers also display a broad range of B concentrations and B isotope ratios with values among the highest known to date (63–68.5‰). This suggests multiple sources and processes affecting B behavior, among which mixing with saline water, B sorption on clays and mixing with wastewater. The highly fractionated B isotopic values were explained by infiltration of relatively salty water with B interacting with clays, pointing out the major role played by (palaeo)-channels for the deep Beberibe aquifer recharge. Based on an increase of salinity at the end of the dry season, a present-day seawater intrusion is identified in the surficial Boa Viagem aquifer. Our conceptual model presents a comprehensive understanding of the major groundwater salinization pathways and processes, and should be of benefit for other southern Atlantic coastal aquifers to better address groundwater management issues. - Highlights: �

A Greedy Approach for Placement of Subsurface Aquifer Wells in an Ensemble Filtering Framework

KAUST Repository

El Gharamti, Mohamad; Marzouk, Youssef M.; Huan, Xun; Hoteit, Ibrahim

2015-01-01

Optimizing wells placement may help in better understanding subsurface solute transport and detecting contaminant plumes. In this work, we use the ensemble Kalman filter (EnKF) as a data assimilation tool and propose a greedy observational design algorithm to optimally select aquifer wells locations for updating the prior contaminant ensemble. The algorithm is greedy in the sense that it operates sequentially, without taking into account expected future gains. The selection criteria is based on maximizing the information gain that the EnKF carries during the update of the prior uncertainties. We test the efficiency of this algorithm in a synthetic aquifer system where a contaminant plume is set to migrate over a 30 years period across a heterogenous domain.

A Greedy Approach for Placement of Subsurface Aquifer Wells in an Ensemble Filtering Framework

KAUST Repository

El Gharamti, Mohamad

2015-11-26

Optimizing wells placement may help in better understanding subsurface solute transport and detecting contaminant plumes. In this work, we use the ensemble Kalman filter (EnKF) as a data assimilation tool and propose a greedy observational design algorithm to optimally select aquifer wells locations for updating the prior contaminant ensemble. The algorithm is greedy in the sense that it operates sequentially, without taking into account expected future gains. The selection criteria is based on maximizing the information gain that the EnKF carries during the update of the prior uncertainties. We test the efficiency of this algorithm in a synthetic aquifer system where a contaminant plume is set to migrate over a 30 years period across a heterogenous domain.

Comparison of fluid geochemistry and microbiology of multiple organic-rich reservoirs in the Illinois Basin, USA: Evidence for controls on methanogenesis and microbial transport

Energy Technology Data Exchange (ETDEWEB)

Schlegel, M.E.; McIntosh, J.C.; Bates, B.L.; Kirk, M.F.; Martini, A.M. [University of Arizona, Tucson, AZ (United States)

2011-04-01

The Illinois Basin, USA, is an ideal location to investigate hydrogeochemical factors controlling methanogenesis as microbial methane accumulations occur: (1) in three organic-rich reservoirs of different geologic ages and organic matter types - Upper Devonian New Albany Shale (up to 900 m depth), Pennsylvanian coals (up to 600 m depth), and Quaternary glacial sediments (shallow aquifers); (2) across steep salinity gradients; and (3) with variable concentrations of SO{sub 4}{sup 2-}. For all three organic-rich reservoirs aqueous geochemical conditions are favorable for microbial methanogenesis, with near neutral pH, SO{sub 4}{sup 2-} concentrations {gt}2 mM, and Cl{sup -} concentrations {lt}3 M. Also, carbon isotopic fractionation of CH{sub 4}, CO{sub 2}, and DIC is consistent with microbial methanogenesis, and increased carbon isotopic fractionation with average reservoir depth corresponds to a decrease of groundwater flushing rates with average depth of reservoir. Plots of stable isotopes of water and Cl{sup -} show mixing between a brine endmember and freshwater, suggesting that meteoric groundwater recharge has affected all microbial methanogenic systems. Additionally, similar methanogenic communities are present in all three reservoirs with comparable cell counts (8.69E3-2.58E6 cells/mL). TRFLP results show low numbers of archaea species with only two dominant groups of base pairs in coals, shale, and limestone aquifers. These results compare favorably with other methanogen-containing deep subsurface environments. The matching of variations between methanogenic TRFLP data and conservative tracers suggests that deep circulation of meteoric waters influenced archaeal communities in the Illinois Basin.

Synergy of climate change and local pressures on saltwater intrusion in heterogeneous coastal aquifers

Science.gov (United States)

Abou Najm, M.; Safi, A.; El-Fadel, M.; Doummar, J.; Alameddine, I.

2016-12-01

The relative importance of climate change induced sea level rise on the salinization of a highly urbanized karstified coastal aquifers were compared with non-sustainable pumping. A 3D variable-density groundwater flow and solute transport model was used to predict the displacement of the saltwater-freshwater interface in a pilot aquifer located along the Eastern Mediterranean. The results showed that the influence of sea level rise was marginal when compared with the encroachment of salinity associated with anthropogenic abstraction. Model predictions of salinity mass and volumetric displacement of the interface corresponding to a long-term monthly transient model showed that the saltwater intrusion dynamic is highly sensitive to change in the abstraction rates which were estimated based on combinations of water consumption rates and population growth rates. Salinity encroachment, however, appeared to be more sensitive to water consumption rates in comparison to population growth rates, where a 50% increase in the rate of former led to four times more intrusion as compared to an equivalent increase in population growth rate over 20 years. Coupling both increase in population growth and increased consumption rates had a synergistic effect that aggravated the intrusion beyond the sum of the individual impacts. Adaptation strategies targeting a decrease in groundwater exploitation proved to be effective in retarding the intrusion.

Comparison of aquifer characteristics derived from local and regional aquifer tests.

Science.gov (United States)

Randolph, R.B.; Krause, R.E.; Maslia, M.L.

1985-01-01

A comparison of the aquifer parameter values obtained through the analysis of a local and a regional aquifer test involving the same area in southeast Georgia is made in order to evaluate the validity of extrapolating local aquifer-test results for use in large-scale flow simulations. Time-drawdown and time-recovery data were analyzed by using both graphical and least-squares fitting of the data to the Theis curve. Additionally, directional transmissivity, transmissivity tensor, and angle of anisotropy were computed for both tests. -from Authors Georgia drawdown transmissivity regional aquifer tests

Evaluation and Preliminary Design of a Stormwater Aquifer Storage and Recovery (ASR) System at the Wadi Khulays Dunefield in Saudi Arabia

KAUST Repository

Lopez Valencia, Oliver M.

2013-04-01

An important source of freshwater in arid lands is found in groundwater aquifers that are recharged after storm events. However, most of the precipitation is lost due to evaporation and only small fractions actually recharge the aquifers. The construction of dams along wadi channels enables the retention of stormwater, however the reservoirs are still subject to huge evaporative losses and contamination. In this study, the hydraulic properties of a dunefield in western Saudi Arabia are evaluated in order to determine the feasibility of designing a stormwater storage aquifer storage and recovery facility using the dune sands as a natural medium and design recommendations are addressed. The accurate estimation of hydraulic conductivity of unlithified sediments such as dune sands has become very important in the design of natural filtration projects, including aquifer recharge and recovery systems. Therefore, a comparison and selection of methods for the determination of the hydraulic conductivity from grain size distribution found in the literature was done. An improvement to these equations based on measurements on dune samples was obtained.

Geology of the Roswell artesian basin, New Mexico, and its relation to the Hondo Reservoir and Effect on artesian aquifer storage of flood water in Hondo Reservoir

Science.gov (United States)

Bean, Robert T.; Theis, Charles V.

1949-01-01

In the Roswell Basin in southeastern New Mexico artesian water is produced from cavernous zones in the carbonate rocks of the San Andres formation and the lower part of the Chalk Bluff formation, both of Permian age. The Hondo Reservoir, 9 miles west-southwest of Roswell, was completed by the U. S. Bureau of Reclamation in 1907, to store waters of the Rio Hondo for irrigation. The project was not successful, as the impounded water escaped rapidly through holes in the gypsum and limestone of the San Andres formation constituting its floor. Of 27,000 acre~feet that entered the reservoir between 1908 and 1913, only 1,100 acre-feet was drawn Ollt for use, the remainder escaping through the floor of the reservoir. Since 1939, plans have been drawn up by the State Engineer and by Federal agencies to utilize the reservoir to protect Roswell from floods. It has also been suggested that water from the Pecos River might be diverted into underground storage through the reservoir. Sinkholes in the Roswell Basin are largely clustered in areas where gypsum occurs in the bedrock. Collapse of strata is due to solution of underlying rock commonly containing gypsum. Domes occur in gypsiferous strata near Salt Creek. The Bottomless Lakes, sinkhole lakes in the escarpment on the east side of the Pecos, are believed to have developed in north-south hinge-line fractures opened when the westernmost beds in the escarpment collapsed. Collapse was due to solution and removal of gypsiferous rock by artesian water which now fills the lakes.

The Importance of Bank Storage in Supplying Baseflow to Rivers Flowing Through Compartmentalized, Alluvial Aquifers

Science.gov (United States)

Rhodes, Kimberly A.; Proffitt, Tiffany; Rowley, Taylor; Knappett, Peter S. K.; Montiel, Daniel; Dimova, Natasha; Tebo, Daniel; Miller, Gretchen R.

2017-12-01

As water grows scarcer in semiarid and arid regions around the world, new tools are needed to quantify fluxes of water and chemicals between aquifers and rivers. In this study, we quantify the volumetric flux of subsurface water to a 24 km reach of the Brazos River, a lowland river that meanders through the Brazos River Alluvium Aquifer (BRAA), with 8 months of high-frequency differential gaging measurements using fixed gaging stations. Subsurface discharge sources were determined using natural tracers and End-Member Mixing Analysis (EMMA). During a 4 month river stage recession following a high stage event, subsurface discharge decreased from 50 m3/s to 0, releasing a total of 1.0 × 108 m3 of water. Subsurface discharge dried up even as the groundwater table at two locations in the BRAA located 300-500 m from the river remained ˜4 m higher than the river stage. Less than 4% of the water discharged from the subsurface during the prolonged recession period resembled the chemical fingerprint of the alluvial aquifer. Instead, the chemistry of this discharged water closely resembled high stage "event" river water. Together, these findings suggest that the river is well connected to rechargeable bank storage reservoirs but disconnected from the broader alluvial aquifer. The average width of discrete bank storage zones on each side of the river, identified with Electrical Resistivity Tomography (ERT), was approximately 1.5 km. In such highly compartmentalized aquifers, groundwater pumping is unlikely to impact the exchange between the river and the alluvium.

Tracer test modeling for characterizing heterogeneity and local scale residence time distribution in an artificial recharge site.

Science.gov (United States)

Valhondo, Cristina; Martinez-Landa, Lurdes; Carrera, Jesús; Hidalgo, Juan J.; Ayora, Carlos

2017-04-01

Artificial recharge of aquifers (AR) is a standard technique to replenish and enhance groundwater resources, that have widely been used due to the increasing demand of quality water. AR through infiltration basins consists on infiltrate surface water, that might be affected in more or less degree by treatment plant effluents, runoff and others undesirables water sources, into an aquifer. The water quality enhances during the passage through the soil and organic matter, nutrients, organic contaminants, and bacteria are reduced mainly due to biodegradation and adsorption. Therefore, one of the goals of AR is to ensure a good quality status of the aquifer even if lesser quality water is used for recharge. Understand the behavior and transport of the potential contaminants is essential for an appropriate management of the artificial recharge system. The knowledge of the flux distribution around the recharge system and the relationship between the recharge system and the aquifer (area affected by the recharge, mixing ratios of recharged and native groundwater, travel times) is essential to achieve this goal. Evaluate the flux distribution is not always simple because the complexity and heterogeneity of natural systems. Indeed, it is not so much regulate by hydraulic conductivity of the different geological units as by their continuity and inter-connectivity particularly in the vertical direction. In summary for an appropriate management of an artificial recharge system it is needed to acknowledge the heterogeneity of the media. Aiming at characterizing the residence time distribution (RTDs) of a pilot artificial recharge system and the extent to which heterogeneity affects RTDs, we performed and evaluated a pulse injection tracer test. The artificial recharge system was simulated as a multilayer model which was used to evaluate the measured breakthrough curves at six monitoring points. Flow and transport parameters were calibrated under two hypotheses. The first

Continental hydrosystem modelling: the concept of nested stream-aquifer interfaces

Science.gov (United States)

Flipo, N.; Mouhri, A.; Labarthe, B.; Biancamaria, S.; Rivière, A.; Weill, P.

2014-08-01

Coupled hydrological-hydrogeological models, emphasising the importance of the stream-aquifer interface, are more and more used in hydrological sciences for pluri-disciplinary studies aiming at investigating environmental issues. Based on an extensive literature review, stream-aquifer interfaces are described at five different scales: local [10 cm-~10 m], intermediate [~10 m-~1 km], watershed [10 km2-~1000 km2], regional [10 000 km2-~1 M km2] and continental scales [>10 M km2]. This led us to develop the concept of nested stream-aquifer interfaces, which extends the well-known vision of nested groundwater pathways towards the surface, where the mixing of low frequency processes and high frequency processes coupled with the complexity of geomorphological features and heterogeneities creates hydrological spiralling. This conceptual framework allows the identification of a hierarchical order of the multi-scale control factors of stream-aquifer hydrological exchanges, from the larger scale to the finer scale. The hyporheic corridor, which couples the river to its 3-D hyporheic zone, is then identified as the key component for scaling hydrological processes occurring at the interface. The identification of the hyporheic corridor as the support of the hydrological processes scaling is an important step for the development of regional studies, which is one of the main concerns for water practitioners and resources managers. In a second part, the modelling of the stream-aquifer interface at various scales is investigated with the help of the conductance model. Although the usage of the temperature as a tracer of the flow is a robust method for the assessment of stream-aquifer exchanges at the local scale, there is a crucial need to develop innovative methodologies for assessing stream-aquifer exchanges at the regional scale. After formulating the conductance model at the regional and intermediate scales, we address this challenging issue with the development of an

Numerical simulation of flow in deep open boreholes in a coastal freshwater lens, Pearl Harbor Aquifer, O‘ahu, Hawai‘i

Science.gov (United States)

Rotzoll, Kolja

2012-01-01

.65 percent seawater salinity. Groundwater withdrawals and drawdowns generally occur at shallow depths in the freshwater system with respect to the depth of the DMW and cause upward flow in the DMW. Simulated groundwater withdrawal of 4.3 million gallons per day that is 100 ft from a DMW causes thirty times more borehole flow than borehole flow that is induced by the regional flow field alone. The displacement of the 2 percent borehole salinity depth increases from 17 to 33 ft, and the average salinity difference between aquifer and borehole is 0.85 percent seawater salinity. Peak borehole flow caused by local groundwater withdrawal near DMWs is directly proportional to the pumping rate in the nearby production well. Increasing groundwater withdrawal to 16.7 million gallons per day increases upward displacement of the 50 percent salinity depth (midpoint of the transition zone) from 4.6 to 77 ft, and the average salinity difference between aquifer and borehole is 1.4 percent seawater salinity. Simulated groundwater withdrawal that is 3,000 ft away from DMWs causes less borehole flow and salinity displacements than nearby withdrawal. Simulated effects of groundwater withdrawal from a horizontal shaft and withdrawal from a vertical well in a homogeneous aquifer were similar. Generally, the 50 percent salinity depths are less affected by borehole flow than the 2 percent salinity depths. Hence, measured salinity profiles are useful for calibration of regional numerical models despite borehole-flow effects. Commonly, a 1 percent error in salinity is acceptable in numerical modeling studies. Incorporation of heterogeneity in the model is necessary to simulate long vertical steps observed in salinity profiles in southern O‘ahu. A thick zone of low aquifer hydraulic conductivity limits exchange of water between aquifer and well and creates a long vertical step in the salinity profile. A heterogeneous basalt-aquifer scenario simulates observed vertical salinity steps and borehole

Isotopes to Study the coastal aquifer plain, Cap Bon, Tunisia

International Nuclear Information System (INIS)

Ben Hamouda, M. F.; Zouari, Kamel; Tarhouni, J.; Gaye, C.B.; Oueslati, M.N.

2005-01-01

The study area is located in the northeastern part of Tunisia about 60 km south of the Tunis city. It is bounded by the Gulf of Haematite in the East, Djebel Sidi Aberahmane in the West, The town of Nabeul in the south and the area of the town Kelibia in the north. The landscape is a coastal plain slightly sloping (3%) towards the sea. The groundwater of the Oriental coast aquifer system occurs mainly at two levels, a shallow aquifer up to depths of about 50 m whose reservoir is consisted by sediments of the Plio quaternary and a deep aquifer between about 150 and 400 m located in the sand stone formations of Miocene of the anticline of Djebel Sidi Abderrahmene. The climate of the region is semi-arid to sub-humid and of Mediterranean type. There are no perennial rivers in this region; but intense storms occasionally cause surface runoff, which is discharged by the oueds. The study is related to a technical cooperation project with the International Atomic Energy Agency, Vienna, Austria, aimed at the use of isotope techniques to study the seawater intrusion into the coastal aquifers of Cap Bon in Tunisia. In this regard, a better understanding of the recharge and flow regime as well as the origin or salinity of the groundwater was required. To reach this goal, isotope and geochemical investigations were carried out. Water samples were taken from wells, boreholes from deep and shallow aquifer of the Oriental coastal aquifer located between Beni Khiar in the south and Kelibia in the north. The samples were analysed for their chemical and isotopic compositions (18O, 2H, 3H, 13C, 14C, 34S). In the following, the results of these analyses are presented and discussed in terms of the recharge and flow regime of the groundwater and the origin and evolution of its salinity. The results of geochemical and isotopic studies have shown that the groundwater is very eterogeneous and suggest the aquifer is replenished by recent water coming from direct infiltration from rain. At

Groundwater storage and water security: making better use of our largest reservoir.

Science.gov (United States)

Tuinhof, A; Olsthoorn, T; Heederik, J P; de Vries, J

2005-01-01

Provision of sufficient storage capacity under growing water demands and increasing climate variability is one the main concerns for water managers in the coming decades. It is expected that 150-300 km3 of additional storage capacity will be needed by 2025 especially in semi-arid and arid regions where changes in climate variability will have most impact on rainfall and drought. Storage of substantial amounts of water can either be above ground, in reservoirs behind dams or underground in aquifers (sub-surface storage). Recharge enhancement through management of aquifer recharge (MAR) and sub-surface storage (SSS) is a known technology and already successfully applied in a number of countries for many years at different scales. MAR-SSS is a flexible and cost-effective means to increase storage capacity both at village level and in modern water management schemes. A dialogue and information exchange between climate experts and water managers can provide an effective contribution to the planning, design and operation of MAR-SSS schemes.

Hydrology of the Claiborne aquifer and interconnection with the Upper Floridan aquifer in southwest Georgia

Science.gov (United States)

Gordon, Debbie W.; Gonthier, Gerard

2017-04-24

The U.S. Geological Survey conducted a study, in cooperation with the Georgia Environmental Protection Division, to define the hydrologic properties of the Claiborne aquifer and evaluate its connection with the Upper Floridan aquifer in southwest Georgia. The effort involved collecting and compiling hydrologic data from the aquifer in subarea 4 of southwestern Georgia. Data collected for this study include borehole geophysical logs in 7 wells, and two 72-hour aquifer tests to determine aquifer properties.The top of the Claiborne aquifer extends from an altitude of about 200 feet above the North American Vertical Datum of 1988 (NAVD 88) in Terrell County to 402 feet below NAVD 88 in Decatur County, Georgia. The base of the aquifer extends from an altitude of about 60 feet above NAVD 88 in eastern Sumter County to about 750 feet below NAVD 88 in Decatur County. Aquifer thickness ranges from about 70 feet in eastern Early County to 400 feet in Decatur County.The transmissivity of the Claiborne aquifer, determined from two 72-hour aquifer tests, was estimated to be 1,500 and 700 feet squared per day in Mitchell and Early Counties, respectively. The storage coefficient was estimated to be 0.0006 and 0.0004 for the same sites, respectively. Aquifer test data from Mitchell County indicate a small amount of leakage occurred during the test. Groundwater-flow models suggest that the source of the leakage was the underlying Clayton aquifer, which produced about 2.5 feet of drawdown in response to pumping in the Claiborne aquifer. The vertical hydraulic conductivity of the confining unit between the Claiborne and Clayton aquifers was simulated to be about 0.02 foot per day.Results from the 72-hour aquifer tests run for this study indicated no interconnection between the Claiborne and overlying Upper Floridan aquifers at the two test sites. Additional data are needed to monitor the effects that increased withdrawals from the Claiborne aquifer may have on future water resources.

Snowmelt induced hydrologic perturbations drive dynamic microbiological and geochemical behaviors across a shallow riparian aquifer

Directory of Open Access Journals (Sweden)

Robert eDanczak

2016-05-01

Full Text Available Shallow riparian aquifers represent hotspots of biogeochemical activity in the arid western US. While these environments provide extensive ecosystem services, little is known of how natural environmental perturbations influence subsurface microbial communities and associated biogeochemical processes. Over a six-month period we tracked the annual snowmelt-driven incursion of groundwater into the vadose zone of an aquifer adjacent to the Colorado River, leading to increased dissolved oxygen (DO concentrations in the normally suboxic saturated zone. Strong biogeochemical heterogeneity was measured across the site, with abiotic reactions between DO and sulfide minerals driving rapid DO consumption and mobilization of redox active species in reduced aquifer regions. Conversely, extensive DO increases were detected in less reduced sediments. 16S rRNA gene surveys tracked microbial community composition within the aquifer, revealing strong correlations between increases in putative oxygen-utilizing chemolithoautotrophs and heterotrophs and rising DO concentrations. The gradual return to suboxic aquifer conditions favored increasing abundances of 16S rRNA sequences matching members of the Microgenomates (OP11 and Parcubacteria (OD1 that have been strongly implicated in fermentative processes. Microbial community stability measurements indicated that deeper aquifer locations were relatively less affected by geochemical perturbations, while communities in shallower locations exhibited the greatest change. Reactive transport modeling of the geochemical and microbiological results supported field observations, suggesting that a predictive framework can be applied to develop a greater understanding of such environments.

Snowmelt induced hydrologic perturbations drive dynamic microbiological and geochemical behaviors across a shallow riparian aquifer

Science.gov (United States)

Danczak, Robert; Yabusaki, Steven; Williams, Kenneth; Fang, Yilin; Hobson, Chad; Wilkins, Michael

2016-05-01

Shallow riparian aquifers represent hotspots of biogeochemical activity in the arid western US. While these environments provide extensive ecosystem services, little is known of how natural environmental perturbations influence subsurface microbial communities and associated biogeochemical processes. Over a six-month period we tracked the annual snowmelt-driven incursion of groundwater into the vadose zone of an aquifer adjacent to the Colorado River, leading to increased dissolved oxygen (DO) concentrations in the normally suboxic saturated zone. Strong biogeochemical heterogeneity was measured across the site, with abiotic reactions between DO and sulfide minerals driving rapid DO consumption and mobilization of redox active species in reduced aquifer regions. Conversely, extensive DO increases were detected in less reduced sediments. 16S rRNA gene surveys tracked microbial community composition within the aquifer, revealing strong correlations between increases in putative oxygen-utilizing chemolithoautotrophs and heterotrophs and rising DO concentrations. The gradual return to suboxic aquifer conditions favored increasing abundances of 16S rRNA sequences matching members of the Microgenomates (OP11) and Parcubacteria (OD1) that have been strongly implicated in fermentative processes. Microbial community stability measurements indicated that deeper aquifer locations were relatively less affected by geochemical perturbations, while communities in shallower locations exhibited the greatest change. Reactive transport modeling of the geochemical and microbiological results supported field observations, suggesting that a predictive framework can be applied to develop a greater understanding of such environments.

Pore-scale simulations of concentration tails in heterogeneous porous media

Science.gov (United States)

Di Palma, Paolo Roberto; Parmigiani, Andrea; Huber, Christian; Guyennon, Nicolas; Viotti, Paolo

2017-10-01

The retention of contaminants in the finest and less-conductive regions of natural aquifer is known to strongly affect the decontamination of polluted aquifers. In fact, contaminant transfer from low to high mobility regions at the back end of a contaminant plume (i.e. back diffusion) is responsible for the long-term release of contaminants during remediation operation. In this paper, we perform pore-scale calculations for the transport of contaminant through heterogeneous porous media composed of low and high mobility regions with two objectives: (i) study the effect of permeability contrast and solute transport conditions on the exchange of solutes between mobile and immobile regions and (ii) estimate the mass of contaminants sequestered in low mobility regions based on concentration breakthrough curves.

Thermodynamic and hydrochemical controls on CH4 in a coal seam gas and overlying alluvial aquifer: new insights into CH4 origins

OpenAIRE

Owen, D. Des. R.; Shouakar-Stash, O.; Morgenstern, U.; Aravena, R.

2016-01-01

Using a comprehensive data set (dissolved CH4, ?13C-CH4, ?2H-CH4, ?13C-DIC, ?37Cl, ?2H-H2O, ?18O-H2O, Na, K, Ca, Mg, HCO3, Cl, Br, SO4, NO3 and DO), in combination with a novel application of isometric log ratios, this study describes hydrochemical and thermodynamic controls on dissolved CH4 from a coal seam gas reservoir and an alluvial aquifer in the Condamine catchment, eastern Surat/north-western Clarence-Moreton basins, Australia. ?13C-CH4 data in the gas reservoir (?58? to ?49?) and sha...

An evaluation of aquifer intercommunication between the unconfined and Rattlesnake Ridge aquifers on the Hanford Site

International Nuclear Information System (INIS)

Jensen, E.J.

1987-10-01

During 1986, Pacific Northwest Laboratory conducted a study of a portion of the Rattlesnake Ridge aquifer (confined aquifer) that lies beneath the B Pond - Gable Mountain Pond area of the Hanford Site. The purpose was to determine the extent of intercommunication between the unconfined aquifer and the uppermost regionally extensive confined aquifer, referred to as the Rattlesnake Ridge aquifer. Hydraulic head data and chemical data were collected from the ground water in the study area during December 1986. The hydraulic head data were used to determine the effects caused by water discharged to the ground from B Pond on both the water table of the unconfined aquifer and the potentiometric surface of the confined aquifer. The chemical data were collected to determine the extent of chemical constituents migrating from the unconfined aquifer to the confined aquifer. Analysis of chemical constituents in the Rattlesnake Ridge aquifer demonstrated that communication between the unconfined and confined aquifers had occurred. However, the levels of contaminants found in the Rattlesnake Ridge aquifer during this study were below the DOE Derived Concentration Guides

Incorporating the Impacts of Small Scale Rock Heterogeneity into Models of Flow and Trapping in Target UK CO2 Storage Systems

Science.gov (United States)

Jackson, S. J.; Reynolds, C.; Krevor, S. C.

2017-12-01

Predictions of the flow behaviour and storage capacity of CO2 in subsurface reservoirs are dependent on accurate modelling of multiphase flow and trapping. A number of studies have shown that small scale rock heterogeneities have a significant impact on CO2flow propagating to larger scales. The need to simulate flow in heterogeneous reservoir systems has led to the development of numerical upscaling techniques which are widely used in industry. Less well understood, however, is the best approach for incorporating laboratory characterisations of small scale heterogeneities into models. At small scales, heterogeneity in the capillary pressure characteristic function becomes significant. We present a digital rock workflow that combines core flood experiments with numerical simulations to characterise sub-core scale capillary pressure heterogeneities within rock cores from several target UK storage reservoirs - the Bunter, Captain and Ormskirk sandstone formations. Measured intrinsic properties (permeability, capillary pressure, relative permeability) and 3D saturations maps from steady-state core flood experiments were the primary inputs to construct a 3D digital rock model in CMG IMEX. We used vertical end-point scaling to iteratively update the voxel by voxel capillary pressure curves from the average MICP curve; with each iteration more closely predicting the experimental saturations and pressure drops. Once characterised, the digital rock cores were used to predict equivalent flow functions, such as relative permeability and residual trapping, across the range of flow conditions estimated to prevail in the CO2 storage reservoirs. In the case of the Captain sandstone, rock cores were characterised across an entire 100m vertical transect of the reservoir. This allowed analysis of the upscaled impact of small scale heterogeneity on flow and trapping. Figure 1 shows the varying degree to which heterogeneity impacted flow depending on the capillary number in the

Characterization of heterogeneous reservoirs: sentinels method and quantification of uncertainties; Caracterisation des reservoirs heterogenes: methode des sentinelles et quantification des incertitudes

Energy Technology Data Exchange (ETDEWEB)

Mezghani, M.

1999-02-11

The aim of this thesis is to propose a new inversion method to allow both an improved reservoir characterization and a management of uncertainties. In this approach, the identification of the permeability distribution is conducted using the sentinel method in order to match the pressure data. This approach, based on optimal control theory, can be seen as an alternative of least-squares method. Here, we prove the existence of exact sentinels under regularity hypothesis. From a numerical point of view, we consider regularized sentinels. We suggest a novel approach to update the penalization coefficient in order to improve numerical robustness. Moreover, the flexibility of the sentinel method enables to develop a way to treat noisy pressure data. To deal with geostatistical modelling of permeability distribution, we propose to link the pilot point method with sentinels to reach the identification of permeability. We particularly focus on the optimal location of pilot points. Finally, we present an original method, based on adjoint state computations, to quantify the dynamic data contribution to the characterisation of a calibrated geostatistical model. (author) 67 refs.

Out of sight, but in their minds: Brazil and its neighbours work together to protect one of the world’s largest groundwater reservoirs

International Nuclear Information System (INIS)

Jawerth, Nicole

2015-01-01

Shrouded in mystery, the future of the largest groundwater reservoir in Latin America once left scientists, academics and politicians in Brazil, Argentina, Paraguay and Uruguay concerned about the fate of their major freshwater resource. Uncovering clues using nuclear techniques, Brazil and its neighbours are now well-acquainted with the Guarani Aquifer and can confidently expect that, with their new protection and sustainable use framework, water from the aquifer will continue to flow for at least another 200 years. Using isotope hydrology, a nuclear technique (see box), the four countries analysed and assessed the aquifer to evaluate the age, origin and evolution of the groundwater, as well as its quality and the risk of contamination. “The studies were an important contribution to the project because they generated an integrated picture of the whole aquifer, which helped to interpret many important geological, hydrochemical and hydrogeological findings,” said Hung Kiang Chang, Professor at the Institute of Geosciences and Exact Sciences (IGCE) at the São Paulo State University.

Diagnosis of the Ghiss Nekor aquifer in order to elaborate the aquifer contract

Science.gov (United States)

Baite, Wissal; Boukdir, A.; Zitouni, A.; Dahbi, S. D.; Mesmoudi, H.; Elissami, A.; Sabri, E.; Ikhmerdi, H.

2018-05-01

The Ghiss-Nekor aquifer, located in the north-east of the action area of the ABHL, plays a strategic role in the drinkable water supply of the city of Al Hoceima and of the neighboring urban areas. It also participates in the irrigation of PMH. However, this aquifer has problems such as over-exploitation and pollution. In the face of these problems, the only Solution is the establishment of a new mode of governance, which privileges the participation, the involvement and the responsibility of the actors concerned in a negotiated contractual framework, namely the aquifer contract. The purpose of this study is to diagnose the current state of the Ghiss Nekor aquifer, the hydrogeological characterization of the aquifer, the use of the waters of the aquifer, the Problem identification and the introduction of the aquifer contract, which aims at the participatory and sustainable management of underground water resources in the Ghiss- Nekor plain, to ensure sustainable development.

Transport of Cryptosporidium parvum Oocysts in Charge Heterogeneous Porous Media: Microfluidics Experiment and Numerical Simulation

Science.gov (United States)

Liu, Y.; Meng, X.; Guo, Z.; Zhang, C.; Nguyen, T. H.; Hu, D.; Ji, J.; Yang, X.

2017-12-01

Colloidal attachment on charge heterogeneous grains has significant environmental implications for transport of hazardous colloids, such as pathogens, in the aquifer, where iron, manganese, and aluminium oxide minerals are the major source of surface charge heterogeneity of the aquifer grains. A patchwise surface charge model is often used to describe the surface charge heterogeneity of the grains. In the patchwise model, the colloidal attachment efficiency is linearly correlated with the fraction of the favorable patches (θ=λ(θf - θu)+θu). However, our previous microfluidic study showed that the attachment efficiency of oocysts of Cryptosporidium parvum, a waterborne protozoan parasite, was not linear correlated with the fraction of the favorable patches (λ). In this study, we developed a pore scale model to simulate colloidal transport and attachment on charge heterogeneous grains. The flow field was simulated using the LBM method and colloidal transport and attachment were simulated using the Lagrange particle tracking method. The pore scale model was calibrated with experimental results of colloidal and oocyst transport in microfluidic devices and was then used to simulate oocyst transport in charge heterogeneous porous media under a variety of environmental relative conditions, i.e. the fraction of favorable patchwise, ionic strength, and pH. The results of the pore scale simulations were used to evaluate the effect of surface charge heterogeneity on upscaling of oocyst transport from pore to continuum scale and to develop an applicable correlation between colloidal attachment efficiency and the fraction of the favorable patches.

Characterization of oil and gas reservoir heterogeneity. Annual report, November 1, 1990--October 31, 1991

Energy Technology Data Exchange (ETDEWEB)

1991-12-31

The objective of the cooperative research program is to characterize Alaskan reservoirs in terms of their reserves, physical and chemical properties, geologic configuration and structure, and the development potential. The tasks completed during this period include: (1) geologic reservoir description of Endicott Field; (2) petrographic characterization of core samples taken from selected stratigraphic horizons of the West Sak and Ugnu (Brookian) wells; (3) development of a polydispersed thermodynamic model for predicting asphaltene equilibria and asphaltene precipitation from crude oil-solvent mixtures, and (4) preliminary geologic description of the Milne Point Unit.

Interdisciplinary study of reservoir compartments and heterogeneity. Quarterly technical progress report, July 1995--September 1995

Energy Technology Data Exchange (ETDEWEB)

Kirk, C.W. Van; Thompson, R.S.

1995-10-27

This United States Department of Energy (DOE) research project was established to document the integrated team approach for solving reservoir engineering problems. A field study integrating the disciplines of geology, geophysics, and petroleum engineering will be the mechanism for documenting the integrated approach. This is an area of keen interest to the oil and gas industry. The goal will be to provide tools and approaches that can be used to detect reservoir compartments, reach a better reserve estimate, and improve profits early in the life of a field.

Deciphering interaction of regional aquifers in Southern Tunisia using hydrochemistry and isotopic tools

International Nuclear Information System (INIS)

Abid, Kamel; Dulinski, Marek; Ammar, Friha Hadj; Rozanski, Kazimierz; Zouari, Kamel

2012-01-01

Groundwater is the most important source of water supply in southern Tunisia. Previous hydrogeologic and isotopic studies carried out in this region revealed the existence of two major aquifer systems: the “Complex Terminal” (CT) and the “Continental Intercalaire” (CI). Turonian carbonates constitute one of the major aquifer levels of the CT multilayered aquifer. It extends over most of southern Tunisia, and its hydrodynamic regime is largely influenced by tectonics, lithology and recharge conditions. Forty-eight groundwater samples from the CI and Turonian aquifers were collected between January and April 2004 for chemical and isotopic analyses. Hydrochemistry and isotopic tools were combined to get an insight into the processes controlling chemical composition of groundwater and wide-scale interaction of these two aquifer systems. Analysis of the dissolved constituents revealed that several processes control the observed chemical composition: (i) incongruent dissolution of carbonate minerals, (ii) dissolution of evaporitic minerals, and (iii) cation exchange. Dissolution alone cannot account for the observed high supersaturation states of groundwater with respect to calcite and dolomite. The observed supersaturation is most probably linked to geogenic CO 2 entering water-bearing horizons of the CT and CI aquifers via deep tectonic faults and discontinuities and subsequent degassing in the exploitation wells. Presence of geogenic CO 2 in the investigated region was confirmed by C isotope data of the DIC reservoir. The radiocarbon content of the Turonian samples varied between 9.5 and 43 pmc. For CI samples generally lower values were recorded, between 3.8 and 22.5 pmc. Stable isotope composition of Turonian groundwater samples varied from −8.3 to −5.3‰ for δ 18 O and from −60 to −25‰ for δ 2 H. The corresponding ranges of δ values for the Continental Intercalaire samples were from −8.9‰ to −6.9‰ for δ 18 O and from −68.2‰ to �

Determination of timescales of nitrate contamination by groundwater age models in a complex aquifer system

Science.gov (United States)

Koh, E. H.; Lee, E.; Kaown, D.; Lee, K. K.; Green, C. T.

2017-12-01

Timing and magnitudes of nitrate contamination are determined by various factors like contaminant loading, recharge characteristics and geologic system. Information of an elapsed time since recharged water traveling to a certain outlet location, which is defined as groundwater age, can provide indirect interpretation related to the hydrologic characteristics of the aquifer system. There are three major methods (apparent ages, lumped parameter model, and numerical model) to date groundwater ages, which differently characterize groundwater mixing resulted by various groundwater flow pathways in a heterogeneous aquifer system. Therefore, in this study, we compared the three age models in a complex aquifer system by using observed age tracer data and reconstructed history of nitrate contamination by long-term source loading. The 3H-3He and CFC-12 apparent ages, which did not consider the groundwater mixing, estimated the most delayed response time and a highest period of the nitrate loading had not reached yet. However, the lumped parameter model could generate more recent loading response than the apparent ages and the peak loading period influenced the water quality. The numerical model could delineate various groundwater mixing components and its different impacts on nitrate dynamics in the complex aquifer system. The different age estimation methods lead to variations in the estimated contaminant loading history, in which the discrepancy in the age estimation was dominantly observed in the complex aquifer system.

Characterizing fate and transport properties in karst aquifers under different hydrologic conditions

Science.gov (United States)

Rodriguez, E.; Padilla, I. Y.

2017-12-01

Karst landscapes contain very productive aquifers. The hydraulic and hydrogeological characteristics of karst aquifers make these systems capable of storing and transporting large amount of water, but also highly vulnerable to contamination. Their extremely heterogeneous nature prevents accurate prediction in contaminant fate and transport. Even more challenging is to understand the impact of hydrologic conditions changes on fate and transport processes. This studies aims at characterizing fate and transport processes in the karst groundwater system of northern Puerto Rico under different hydrologic conditions. The study involves injecting rhodamine and uranine dyes into a sinkhole, and monitoring concentrations at a spring. Results show incomplete recovery of tracers, but breaking curves can be used to estimate advective, dispersive and mass transfer characteristic of the karst system. Preliminary results suggest significant differences in fate and transport characteristics under different hydrologic conditions.

EPA Region 1 Sole Source Aquifers

Science.gov (United States)

This coverage contains boundaries of EPA-approved sole source aquifers. Sole source aquifers are defined as an aquifer designated as the sole or principal source of drinking water for a given aquifer service area; that is, an aquifer which is needed to supply 50% or more of the drinking water for the area and for which there are no reasonable alternative sources should the aquifer become contaminated.The aquifers were defined by a EPA hydrogeologist. Aquifer boundaries were then drafted by EPA onto 1:24000 USGS quadrangles. For the coastal sole source aquifers the shoreline as it appeared on the quadrangle was used as a boundary. Delineated boundaries were then digitized into ARC/INFO.

Phytoplankton assemblage of a small, shallow, tropical African reservoir.

Science.gov (United States)

Mustapha, Moshood K

2009-12-01

I measured physico-chemical properties and phytoplankton in the small, shallow tropical reservoir of Oyun (Offa, Nigeria) between January 2002 and December 2003. I identified 25 phytoplankton genera in three sampling stations. Bacillariophyceae dominated (75.3%), followed by Chlorophyceae (12.2%), Cyanobacteria (11.1%) and Desmidiaceae (0.73%). The high amount of nutrients (e.g. nitrate, phosphate, sulphate and silica) explain phytoplankton heterogeneity (p<0.05). Phytoplankton was abundant during the rainy season, but the transition period had the richest assemblage and abundance. Fluctuations in phytoplankton density were a result of seasonal changes in concentration of nutrients, grazing pressure and reservoir hydrology. The reservoir is eutrophic with excellent water quality and a diverse phytoplankton assemblage: fish production would be high. These conditions resulted from strategies such as watershed best management practices (BMPs) to control eutrophication and sedimentation, and priorities for water usage established through legislation. Additional measures are recommended to prevent oligotrophy, hypereutrophy, excessive phytoplankton bloom, toxic cyanobacteria, and run-off of organic waste and salts.

How far does the CO2 travel beyond a leaky point?

Science.gov (United States)

Kong, X.; Delshad, M.; Wheeler, M.

2012-12-01

Xianhui Kong, Mojdeh Delshad, Mary F. Wheeler The University of Texas at Austin Numerous research studies have been carried out to investigate the long term feasibility of safe storage of large volumes of CO2 in subsurface saline aquifers. The injected CO2 will undergo complex petrophysical and geochemical processes. During these processes, part of CO2 will be trapped while some will remain as a mobile phase, causing a leakage risk. The comprehensive and accurate characterizations of the trapping and leakage mechanisms are critical for accessing the safety of sequestration, and are challenges in this research area. We have studied different leakage scenarios using realistic aquifer properties including heterogeneity and put forward a comprehensive trapping model for CO2 in deep saline aquifer. The reservoir models include several geological layers and caprocks up to the near surface. Leakage scenarios, such as fracture, high permeability pathways, abandoned wells, are studied. In order to accurately model the fractures, very fine grids are needed near the fracture. Considering that the aquifer usually has a large volume and reservoir model needs large number of grid blocks, simulation would be computational expensive. To deal with this challenge, we carried out the simulations using our in-house parallel reservoir simulator. Our study shows the significance of capillary pressure and permeability-porosity variations on CO2 trapping and leakage. The improved understanding on trapping and leakage will provide confidence in future implementation of sequestration projects.

Microbial Enhanced Oil Recovery - Advanced Reservoir Simulation

DEFF Research Database (Denmark)

Nielsen, Sidsel Marie

the water phase. The biofilm formation implies that the concentration of bacteria near the inlet increases. In combination with surfactant production, the biofilm results in a higher surfactant concentration in the initial part of the reservoir. The oil that is initially bypassed in connection...... simulator. In the streamline simulator, the effect of gravity is introduced using an operator splitting technique. The gravity effect stabilizes oil displacement causing markedly improvement of the oil recovery, when the oil density becomes relatively low. The general characteristics found for MEOR in one......-dimensional simulations are also demonstrated both in two and three dimensions. Overall, this MEOR process conducted in a heterogeneous reservoir also produces more oil compared to waterflooding, when the simulations are run in multiple dimensions. The work presented in this thesis has resulted in two publications so far....

Hydrological connectivity of perched aquifers and regional aquifers in semi-arid environments: a case study from Namibia

Science.gov (United States)

Hamutoko, J. T.; Wanke, H.

2017-12-01

Integrated isotopic and hydrological tracers along with standard hydrological data are used to understand complex dry land hydrological processes on different spatial and temporal scales. The objective of this study is to analyse the relationship between the perched aquifers and the regional aquifer using hydrochemical data and isotopic composition in the Cuvelai-Etosha Basin in Namibia. This relation between the aquifers will aid in understanding groundwater recharge processes and flow dynamics. Perched aquifers are discontinuous shallow aquifers with water level ranging from 0 to 30 meters below ground level. The regional aquifer occurs in semi-consolidated sandstone at depths between about 60 and 160 meters below ground level. Water samples were collected from both aquifers in 10 villages and were analysed for major ions and stable isotopes. The results show overlapping hydrochemistry and isotopic compositions of both aquifers in 8 villages which suggest the possibility of perched aquifer water infiltrating into the regional aquifer. In two villages the hydrochemistry and isotopic composition of the aquifers are totally different and this suggests that there is no interaction between this aquifers. Areas where perched aquifers are connected to regional aquifers maybe recharge zones. These finding have important implications for groundwater resource management.

Magnetotellurics applied to the study of the Guaraní aquifer in Entre Ríos Province, N-E Argentina

Science.gov (United States)

Favetto, Alicia; Curcio, Ana; Pomposiello, Cristina

2011-07-01

The South American Guaraní Aquifer System covers the entire Parana basin and part of the Chaco-Parana basin. This system is one of the most important groundwater reservoirs; it is shared by four neighboring countries covering an area larger than one million square kilometers. The geological units closely related to the Guaraní Aquifer are the Piramboia and Botucatu Formations that consist of Triassic-Jurassic aeolian, fluvial and lacustrine sandstones, and the Serra Geral basalts with clastic intercalations. Serra Geral, an effusive Cretaceous complex, covers the sandstones and provides a high degree of confinement to the system. This paper presents the interpretation of magnetotelluric (MT) data collected during 2007-2008 in Entre Ríos Province, Argentina. These data, recorded in three profiles, mainly provide the depth to the crystalline basement, determinant for the presence of aquifer-related sediments. Models showed that the discrimination of the basalts strongly depends on local electrical characteristics. Model information is quite consistent with the information from oil and thermal wells located close to the profiles.

Earthquakes and depleted gas reservoirs: which comes first?

Science.gov (United States)

Mucciarelli, M.; Donda, F.; Valensise, G.

2015-10-01

While scientists are paying increasing attention to the seismicity potentially induced by hydrocarbon exploitation, so far, little is known about the reverse problem, i.e. the impact of active faulting and earthquakes on hydrocarbon reservoirs. The 20 and 29 May 2012 earthquakes in Emilia, northern Italy (Mw 6.1 and 6.0), raised concerns among the public for being possibly human-induced, but also shed light on the possible use of gas wells as a marker of the seismogenic potential of an active fold and thrust belt. We compared the location, depth and production history of 455 gas wells drilled along the Ferrara-Romagna arc, a large hydrocarbon reserve in the southeastern Po Plain (northern Italy), with the location of the inferred surface projection of the causative faults of the 2012 Emilia earthquakes and of two pre-instrumental damaging earthquakes. We found that these earthquake sources fall within a cluster of sterile wells, surrounded by productive wells at a few kilometres' distance. Since the geology of the productive and sterile areas is quite similar, we suggest that past earthquakes caused the loss of all natural gas from the potential reservoirs lying above their causative faults. To validate our hypothesis we performed two different statistical tests (binomial and Monte Carlo) on the relative distribution of productive and sterile wells, with respect to seismogenic faults. Our findings have important practical implications: (1) they may allow major seismogenic sources to be singled out within large active thrust systems; (2) they suggest that reservoirs hosted in smaller anticlines are more likely to be intact; and (3) they also suggest that in order to minimize the hazard of triggering significant earthquakes, all new gas storage facilities should use exploited reservoirs rather than sterile hydrocarbon traps or aquifers.

A Black Hills-Madison Aquifer origin for Dakota Aquifer groundwater in northeastern Nebraska.

Science.gov (United States)

Stotler, Randy; Harvey, F Edwin; Gosselin, David C

2010-01-01

Previous studies of the Dakota Aquifer in South Dakota attributed elevated groundwater sulfate concentrations to Madison Aquifer recharge in the Black Hills with subsequent chemical evolution prior to upward migration into the Dakota Aquifer. This study examines the plausibility of a Madison Aquifer origin for groundwater in northeastern Nebraska. Dakota Aquifer water samples were collected for major ion chemistry and isotopic analysis ((18)O, (2)H, (3)H, (14)C, (13)C, (34)S, (18)O-SO(4), (87)Sr, (37)Cl). Results show that groundwater beneath the eastern, unconfined portion of the study area is distinctly different from groundwater sampled beneath the western, confined portion. In the east, groundwater is calcium-bicarbonate type, with delta(18)O values (-9.6 per thousand to -12.4 per thousand) similar to local, modern precipitation (-7.4 per thousand to -10 per thousand), and tritium values reflecting modern recharge. In the west, groundwater is calcium-sulfate type, having depleted delta(18)O values (-16 per thousand to -18 per thousand) relative to local, modern precipitation, and (14)C ages 32,000 to more than 47,000 years before present. Sulfate, delta(18)O, delta(2)H, delta(34)S, and delta(18)O-SO(4) concentrations are similar to those found in Madison Aquifer groundwater in South Dakota. Thus, it is proposed that Madison Aquifer source water is also present within the Dakota Aquifer beneath northeastern Nebraska. A simple Darcy equation estimate of groundwater velocities and travel times using reported physical parameters from the Madison and Dakota Aquifers suggests such a migration is plausible. However, discrepancies between (14)C and Darcy age estimates indicate that (14)C ages may not accurately reflect aquifer residence time, due to mixtures of varying aged water.

Hybrid Multi-Objective Optimization of Folsom Reservoir Operation to Maximize Storage in Whole Watershed

Science.gov (United States)

Goharian, E.; Gailey, R.; Maples, S.; Azizipour, M.; Sandoval Solis, S.; Fogg, G. E.

2017-12-01

The drought incidents and growing water scarcity in California have a profound effect on human, agricultural, and environmental water needs. California experienced multi-year droughts, which have caused groundwater overdraft and dropping groundwater levels, and dwindling of major reservoirs. These concerns call for a stringent evaluation of future water resources sustainability and security in the state. To answer to this call, Sustainable Groundwater Management Act (SGMA) was passed in 2014 to promise a sustainable groundwater management in California by 2042. SGMA refers to managed aquifer recharge (MAR) as a key management option, especially in areas with high variation in water availability intra- and inter-annually, to secure the refill of underground water storage and return of groundwater quality to a desirable condition. The hybrid optimization of an integrated water resources system provides an opportunity to adapt surface reservoir operations for enhancement in groundwater recharge. Here, to re-operate Folsom Reservoir, objectives are maximizing the storage in the whole American-Cosumnes watershed and maximizing hydropower generation from Folsom Reservoir. While a linear programing (LP) module tends to maximize the total groundwater recharge by distributing and spreading water over suitable lands in basin, a genetic based algorithm, Non-dominated Sorting Genetic Algorithm II (NSGA-II), layer above it controls releases from the reservoir to secure the hydropower generation, carry-over storage in reservoir, available water for replenishment, and downstream water requirements. The preliminary results show additional releases from the reservoir for groundwater recharge during high flow seasons. Moreover, tradeoffs between the objectives describe that new operation performs satisfactorily to increase the storage in the basin, with nonsignificant effects on other objectives.

Characterization of a managed aquifer recharge system using multiple tracers.

Science.gov (United States)

Moeck, Christian; Radny, Dirk; Popp, Andrea; Brennwald, Matthias; Stoll, Sebastian; Auckenthaler, Adrian; Berg, Michael; Schirmer, Mario

2017-12-31

Knowledge about the residence times of artificially infiltrated water into an aquifer and the resulting flow paths is essential to developing groundwater-management schemes. To obtain this knowledge, a variety of tracers can be used to study residence times and gain information about subsurface processes. Although a variety of tracers exists, their interpretation can differ considerably due to subsurface heterogeneity, underlying assumptions, and sampling and analysis limitations. The current study systematically assesses information gained from seven different tracers during a pumping experiment at a site where drinking water is extracted from an aquifer close to contaminated areas and where groundwater is artificially recharged by infiltrating surface water. We demonstrate that the groundwater residence times estimated using dye and heat tracers are comparable when the thermal retardation for the heat tracer is considered. Furthermore, major ions, acesulfame, and stable isotopes (δ 2 H and δ 18 O) show that mixing of infiltrated water and groundwater coming from the regional flow path occurred and a vertical stratification of the flow system exist. Based on the concentration patterns of dissolved gases (He, Ar, Kr, N 2 , and O 2 ) and chlorinated solvents (e.g., tetrachloroethene), three temporal phases are observed in the ratio between infiltrated water and regional groundwater during the pumping experiment. Variability in this ratio is significantly related to changes in the pumping and infiltration rates. During constant pumping rates, more infiltrated water was extracted, which led to a higher dilution of the regional groundwater. An infiltration interruption caused however, the ratio to change and more regional groundwater is extracted, which led to an increase in all concentrations. The obtained results are discussed for each tracer considered and its strengths and limitations are illustrated. Overall, it is demonstrated that aquifer heterogeneity and

Origins and processes of groundwater salinization in the urban coastal aquifers of Recife (Pernambuco, Brazil): A multi-isotope approach

Energy Technology Data Exchange (ETDEWEB)

Cary, Lise, E-mail: l.cary@brgm.fr [BRGM French Geological Survey, 3 Avenue Claude Guillemin, 45060 Orléans Cedex 2 (France); Petelet-Giraud, Emmanuelle [BRGM French Geological Survey, 3 Avenue Claude Guillemin, 45060 Orléans Cedex 2 (France); Bertrand, Guillaume [Institute of Geosciences, University of São Paulo, Rua do Lago, 562 Butantã, 05508-080 Sao Paulo (Brazil); Kloppmann, Wolfram [BRGM French Geological Survey, 3 Avenue Claude Guillemin, 45060 Orléans Cedex 2 (France); Aquilina, Luc [OSUR-Géosciences Rennes, Université Rennes 1 — CNRS, 35000 Rennes (France); Martins, Veridiana; Hirata, Ricardo [Institute of Geosciences, University of São Paulo, Rua do Lago, 562 Butantã, 05508-080 Sao Paulo (Brazil); Montenegro, Suzana [Civil Engineering Department, Federal University of Pernambuco, 50740 Recife, PE Brazil (Brazil); Pauwels, Hélène [BRGM French Geological Survey, 3 Avenue Claude Guillemin, 45060 Orléans Cedex 2 (France); Chatton, Eliot [OSUR-Géosciences Rennes, Université Rennes 1 — CNRS, 35000 Rennes (France); Franzen, Melissa [CPRM, Brazilian Geologic Survey, Avenida Sul 2291, Recife PE (Brazil); Aurouet, Axel [Géo-Hyd, 101 rue Jacques Charles, 45160 Olivet (France); Lasseur, Eric; Picot, Géraldine; Guerrot, Catherine; Fléhoc, Christine [BRGM French Geological Survey, 3 Avenue Claude Guillemin, 45060 Orléans Cedex 2 (France); and others

2015-10-15

In the coastal multilayer aquifer system of a highly urbanized southern city (Recife, Brazil), where groundwaters are affected by salinization, a multi-isotope approach (Sr, B, O, H) was used to investigate the sources and processes of salinization. The high diversity of the geological bodies, built since the Atlantic opening during the Cretaceous, highly constrains the heterogeneity of the groundwater chemistry, e.g. Sr isotope ratios, and needs to be integrated to explain the salinization processes and groundwater pathways. A paleoseawater intrusion, most probably the 120 ky B.P. Pleistocene marine transgression, and cationic exchange are clearly evidenced in the most salinized parts of the Cabo and Beberibe aquifers. All {sup 87}Sr/{sup 86}Sr values are above the past and present-day seawater signatures, meaning that the Sr isotopic signature is altered due to additional Sr inputs from dilution with different freshwaters, and water–rock interactions. Only the Cabo aquifer presents a well-delimitated area of Na-HCO{sub 3} water typical of a freshening process. The two deep aquifers also display a broad range of B concentrations and B isotope ratios with values among the highest known to date (63–68.5‰). This suggests multiple sources and processes affecting B behavior, among which mixing with saline water, B sorption on clays and mixing with wastewater. The highly fractionated B isotopic values were explained by infiltration of relatively salty water with B interacting with clays, pointing out the major role played by (palaeo)-channels for the deep Beberibe aquifer recharge. Based on an increase of salinity at the end of the dry season, a present-day seawater intrusion is identified in the surficial Boa Viagem aquifer. Our conceptual model presents a comprehensive understanding of the major groundwater salinization pathways and processes, and should be of benefit for other southern Atlantic coastal aquifers to better address groundwater management issues

Seismic velocities to characterize the soil-aquifer continuum on the Orgeval experimental basin (France)

Science.gov (United States)

Pasquet, S.; Ludovic, B.; Dhemaied, A.; Flipo, N.; Guérin, R.; Mouhri, A.; Faycal, R.; Vitale, Q.

2013-12-01

Among geophysical methods applied to hydrogeology, seismic prospecting is frequently confined to the characterization of aquifers geometry. The combined study of pressure- (P) and shear- (SH) wave velocities (respectively Vp and Vs) can however provide information about the aquifer parameters, as it is commonly done for most fluids in hydrocarbon exploration. This approach has recently been proposed in sandy aquifers with the estimation of Vp/Vs ratio. In order to address such issues in more complex aquifer systems (e.g. unconsolidated, heterogeneous or low-permeability media) we carried out P- and SH-wave seismic surveys on the Orgeval experimental basin (70 km east from Paris, France). This basin drains a multi-layer aquifer system monitored by a network of piezometers. The upper part of the aquifer system is characterized by tabular layers well delineated all over the basin thanks to Electrical Resistivity Tomography (ERT), Time Domain ElectroMagnetic (TDEM) soundings and wells. But the lateral variability of the intrinsic properties in each layer raises questions regarding the hydrodynamics of the upper aquifer and the validity of interpolations between piezometers. A simple interpretation of P- and SH-wave first arrivals for tabular models provides 1D velocity structures in very good agreement with the stratification anticipated from ERT and nearby geological logs. Vp/Vs ratios show a strong contrast at a depth consistent with the observed water table level, reinforcing the assumption of a free upper aquifer in the area. Similar experiments have to be conducted under different hydrological conditions to validate these observations. Anticipating the need to propose lateral applications of the method, we additionally performed tomographic inversions of the recorded data to retrieve 2D Vp and Vs models. If interpreted independently, both models fail to depict the stratification of the medium and the water table level cannot be straightforwardly identified

Hydrogeologic and hydraulic characterization of aquifer and nonaquifer layers in a lateritic terrain (West Bengal, India)

Science.gov (United States)

Biswal, Sabinaya; Jha, Madan K.; Sharma, Shashi P.

2018-02-01

The hydrogeologic and hydraulic characteristics of a lateritic terrain in West Bengal, India, were investigated. Test drilling was conducted at ten sites and grain-size distribution curves (GSDCs) were prepared for 275 geologic samples. Performance evaluation of eight grain-size-analysis (GSA) methods was carried out to estimate the hydraulic conductivity (K) of subsurface formations. Finally, the GSA results were validated against pumping-test data. The GSDCs indicated that shallow aquifer layers are coarser than the deeper aquifer layers (uniformity coefficient 0.19-11.4). Stratigraphy analysis revealed that both shallow and deep aquifers of varying thickness exist at depths 9-40 and 40-79 m, respectively. The mean K estimates by the GSA methods are 3.62-292.86 m/day for shallow aquifer layers and 0.97-209.93 m/day for the deeper aquifer layers, suggesting significant aquifer heterogeneity. Pumping-test data indicated that the deeper aquifers are leaky confined with transmissivity 122.69-693.79 m2/day, storage coefficient 1.01 × 10-7-2.13 × 10-4 and leakance 2.01 × 10-7-34.56 × 10-2 day-1. Although the K values yielded by the GSA methods are generally larger than those obtained from the pumping tests, the Slichter, Harleman and US Bureau Reclamation (USBR) GSA methods yielded reasonable values at most of the sites (1-3 times higher than K estimates by the pumping-test method). In conclusion, more reliable aquifers exist at deeper depths that can be tapped for dependable water supply. GSA methods such as Slichter, Harleman and USBR can be used for the preliminary assessment of K in lateritic terrains in the absence of reliable field methods.

Vertically Integrated Models for Carbon Storage Modeling in Heterogeneous Domains

Science.gov (United States)

Bandilla, K.; Celia, M. A.

2017-12-01

Numerical modeling is an essential tool for studying the impacts of geologic carbon storage (GCS). Injection of carbon dioxide (CO2) into deep saline aquifers leads to multi-phase flow (injected CO2 and resident brine), which can be described by a set of three-dimensional governing equations, including mass-balance equation, volumetric flux equations (modified Darcy), and constitutive equations. This is the modeling approach on which commonly used reservoir simulators such as TOUGH2 are based. Due to the large density difference between CO2 and brine, GCS models can often be simplified by assuming buoyant segregation and integrating the three-dimensional governing equations in the vertical direction. The integration leads to a set of two-dimensional equations coupled with reconstruction operators for vertical profiles of saturation and pressure. Vertically-integrated approaches have been shown to give results of comparable quality as three-dimensional reservoir simulators when applied to realistic CO2 injection sites such as the upper sand wedge at the Sleipner site. However, vertically-integrated approaches usually rely on homogeneous properties over the thickness of a geologic layer. Here, we investigate the impact of general (vertical and horizontal) heterogeneity in intrinsic permeability, relative permeability functions, and capillary pressure functions. We consider formations involving complex fluvial deposition environments and compare the performance of vertically-integrated models to full three-dimensional models for a set of hypothetical test cases consisting of high permeability channels (streams) embedded in a low permeability background (floodplains). The domains are randomly generated assuming that stream channels can be represented by sinusoidal waves in the plan-view and by parabolas for the streams' cross-sections. Stream parameters such as width, thickness and wavelength are based on values found at the Ketzin site in Germany. Results from the

Differences in microbial community composition between injection and production water samples of water flooding petroleum reservoirs

Directory of Open Access Journals (Sweden)

P. K. Gao

2015-06-01

Full Text Available Microbial communities in injected water are expected to have significant influence on those of reservoir strata in long-term water flooding petroleum reservoirs. To investigate the similarities and differences in microbial communities in injected water and reservoir strata, high-throughput sequencing of microbial partial 16S rRNA of the water samples collected from the wellhead and downhole of injection wells, and from production wells in a homogeneous sandstone reservoir and a heterogeneous conglomerate reservoir were performed. The results indicate that a small number of microbial populations are shared between the water samples from the injection and production wells in the sandstone reservoir, whereas a large number of microbial populations are shared in the conglomerate reservoir. The bacterial and archaeal communities in the reservoir strata have high concentrations, which are similar to those in the injected water. However, microbial population abundance exhibited large differences between the water samples from the injection and production wells. The number of shared populations reflects the influence of microbial communities in injected water on those in reservoir strata to some extent, and show strong association with the unique variation of reservoir environments.

INTEGRATED GEOLOGIC-ENGINEERING MODEL FOR REEF AND CARBONATE SHOAL RESERVOIRS ASSOCIATED WITH PALEOHIGHS: UPPER JURASSIC SMACKOVER FORMATION, NORTHEASTERN GULF OF MEXICO

Energy Technology Data Exchange (ETDEWEB)

Ernest A. Mancini

2002-09-25

The University of Alabama in cooperation with Texas A&M University, McGill University, Longleaf Energy Group, Strago Petroleum Corporation, and Paramount Petroleum Company are undertaking an integrated, interdisciplinary geoscientific and engineering research project. The project is designed to characterize and model reservoir architecture, pore systems and rock-fluid interactions at the pore to field scale in Upper Jurassic Smackover reef and carbonate shoal reservoirs associated with varying degrees of relief on pre-Mesozoic basement paleohighs in the northeastern Gulf of Mexico. The project effort includes the prediction of fluid flow in carbonate reservoirs through reservoir simulation modeling which utilizes geologic reservoir characterization and modeling and the prediction of carbonate reservoir architecture, heterogeneity and quality through seismic imaging. The primary objective of the project is to increase the profitability, producibility and efficiency of recovery of oil from existing and undiscovered Upper Jurassic fields characterized by reef and carbonate shoals associated with pre-Mesozoic basement paleohighs. The principal research effort for Year 2 of the project has been reservoir characterization, 3-D modeling and technology transfer. This effort has included six tasks: (1) the study of rockfluid interactions, (2) petrophysical and engineering characterization, (3) data integration, (4) 3-D geologic modeling, (5) 3-D reservoir simulation and (6) technology transfer. This work was scheduled for completion in Year 2. Overall, the project work is on schedule. Geoscientific reservoir characterization is essentially completed. The architecture, porosity types and heterogeneity of the reef and shoal reservoirs at Appleton and Vocation Fields have been characterized using geological and geophysical data. The study of rock-fluid interactions is near completion. Observations regarding the diagenetic processes influencing pore system development and

Aquifer thermal-energy-storage modeling

Science.gov (United States)

Schaetzle, W. J.; Lecroy, J. E.

1982-09-01

A model aquifer was constructed to simulate the operation of a full size aquifer. Instrumentation to evaluate the water flow and thermal energy storage was installed in the system. Numerous runs injecting warm water into a preconditioned uniform aquifer were made. Energy recoveries were evaluated and agree with comparisons of other limited available data. The model aquifer is simulated in a swimming pool, 18 ft by 4 ft, which was filled with sand. Temperature probes were installed in the system. A 2 ft thick aquifer is confined by two layers of polyethylene. Both the aquifer and overburden are sand. Four well configurations are available. The system description and original tests, including energy recovery, are described.

Profitability Evaluation of a Hybrid Geothermal and CO2 Sequestration Project for a Coastal Hot Saline Aquifer.

Science.gov (United States)

Plaksina, Tatyana; Kanfar, Mohammed

2017-11-01

With growing interest in commercial projects involving industrial volume CO2 sequestration, a concern about proper containment and control over the gas plume becomes particularly prominent. In this study, we explore the potential of using a typical coastal geopressured hot saline aquifer for two commercial purposes. The first purpose is to harvest geothermal heat of the aquifer for electricity generation and/or direct use and the second one is to utilize the same rock volume for safe and controlled CO2 sequestration without interruption of heat production. To achieve these goals, we devised and economically evaluated a scheme that recovers operational and capital costs within first 4 years and yields positive internal rate of return of about 15% at the end of the operations. Using our strategic design of well placement and operational scheduling, we were able to achieve in our numerical simulation study the following results. First, the hot water production rates allowed to run a 30 MW organic Rankine cycle plant for 20 years. Second, during the last 10 years of operation we managed to inject into the same reservoir (volume of 0.8 x 109 m3) approximately 10 million ton of the supercritical gas. Third, decades of numerical monitoring the plume after the end of the operations showed that this large volume of CO2 is securely sequestrated inside the reservoir without compromising the caprock integrity.

Reservoir characterization of Pennsylvanian sandstone reservoirs. Final report

Energy Technology Data Exchange (ETDEWEB)

Kelkar, M.

1995-02-01

This final report summarizes the progress during the three years of a project on Reservoir Characterization of Pennsylvanian Sandstone Reservoirs. The report is divided into three sections: (i) reservoir description; (ii) scale-up procedures; (iii) outcrop investigation. The first section describes the methods by which a reservoir can be described in three dimensions. The next step in reservoir description is to scale up reservoir properties for flow simulation. The second section addresses the issue of scale-up of reservoir properties once the spatial descriptions of properties are created. The last section describes the investigation of an outcrop.

Effect of pore structure on the seepage characteristics of tight sandstone reservoirs: A case study of Upper Jurassic Penglaizhen Fm reservoirs in the western Sichuan Basin

Directory of Open Access Journals (Sweden)

Liqiang Sima

2017-01-01

Full Text Available Tight sandstone reservoirs are characterized by complex pore structures and strong heterogeneity, and their seepage characteristics are much different from those of conventional sandstone reservoirs. In this paper, the tight sandstone reservoirs of Upper Jurassic Penglaizhen Fm in western Sichuan Basin were analyzed in terms of their pore structures by using the data about physical property, mercury injection and nuclear magnetic resonance (NMR tests. Then, the seepage characteristics and the gas–water two-phase migration mechanisms and distribution of tight sandstone reservoirs with different types of pore structures in the process of hydrocarbon accumulation and development were simulated by combining the relative permeability experiment with the visual microscopic displacement model. It is shown that crotch-like viscous fingering occurs in the process of gas front advancing in reservoirs with different pore structures. The better the pore structure is, the lower the irreducible water saturation is; the higher the gas-phase relative permeability of irreducible water is, the more easily the gas reservoir can be developed. At the late stage of development, the residual gas is sealed in reservoirs in the forms of bypass, cutoff and dead end. In various reservoirs, the interference between gas and water is stronger, so gas and water tends to be produced simultaneously. The sealed gas may reduce the production rate of gas wells significantly, and the existence of water phase may reduce the gas permeability greatly; consequently, the water-bearing low-permeability tight sandstone gas reservoirs reveal serious water production, highly-difficult development and low-recovery percentage at the late stage, which have adverse impacts on the effective production and development of gas wells.

ATES Contribution to the Housing Energy Balance: a Simple Assessment Methodology Contribution du stockage d’énergie thermique en aquifère au bilan énergétique lié à l’habitat : méthodologie d’évaluation rapide