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Permeability Upscaling Measured on a Block of Berea Sandstone: Results and Interpretation

Description: To physically investigate permeability upscaling over 13,000 permeability values were measured with four different sample supports (i.e., sample volumes) on a block of Berea Sandstone. At each sample support spatially-exhaustive permeability data sets were measured, subject to consistent flow geometry and boundary conditions, with a specially adapted minipermeameter test system. Here, we present and analyze a subset of the data consisting of 2304 permeability values collected from a single block face oriented normal to stratification. Results reveal a number of distinct and consistent trends (i.e., upscaling) relating changes in key summary statistics to an increasing sample support. Examples include the sample mean and semivariogram range that increase with increasing sample support and the sample variance that decreases. To help interpret the measured mean upscaling we compared it to theoretical models that are only available for somewhat different flow geometries. The comparison suggests that the non-uniform flow imposed by the rninipermeameter coupled with permeability anisotropy at the scale of the local support (i.e., smallest sample support for which data is available) are the primary controls on the measured upscaling. This work demonstrates, experimentally, that it is not always appropriate to treat the local-support permeability as an intrinsic feature of the porous medium; that is, independent of its conditions of measurement.
Date: May 6, 1999
Creator: Tidwell, Vincent C. & Wilson, John L.
Partner: UNT Libraries Government Documents Department

Microseismic Monitoring of the Mounds Drill Cuttings Injection Tests

Description: This paper describes the microseismic mapping of repeated injections of drill cuttings into two separate formations at a test site near Mounds, OK. Injections were performed in sandstone and shale formations at depths of 830 and 595 m, respectively. Typical injection disposal was simulated using multiple small-volume injections over a three-day period, with long shut-in periods interspersed between the injections. Microseismic monitoring was achieved using a 5-level array of wireline-run, triaxial- accelerometer receivers in a monitor well 76 m from the disposed well. Results of the mapped microseismic locations showed that the disposal domti W= generally aligns with the major horizontal stress with some variations in azimuth and that wide variations in height and length growth occurred with continued injections. These experiments show that the cuttings injection process cm be adequately monitored from a downhole, wireline-run receiver array, thus providing process control and environmental assurance.
Date: January 25, 1999
Creator: Branagan, P.T.; Mahrer, K.D.; Moschovidis, Z.A.; Warpinski, N.R. & Wolhart, S.L.
Partner: UNT Libraries Government Documents Department

Isotope constraints on the involvement of fluids in the San Andreas Fault System, California

Description: Fluids are suspected to play a major role in earthquake mechanics, especially in the case of the weak San Andreas Fault (SAF). Models developed to explain the weakness of the fault are similar but rely on different fluid sources. A recent study of groundwaters associated with the SAF has provided evidence for a geopressured mantle fluid source (Kennedy et al., 1997). We present here an isotope study comparing deformation zones (gouges, breccias, fault veins, slickensides, cataclasites), and vein fillings with their hosts and the fluids associated with these materials, as sampled by fluid inclusions. We are investigating ca. 250 samples from over 20 localities along the San Andreas and adjacent faults from South San Francisco to East Los Angeles. Samples from the exhumed San Gabriel Fault, a deeper equivalent of the SAF, are included as well as samples from the Santa Ynez Fault, another former strand of the SAF embedded in Miocene limestones. All the major lithologies (granites, gneisses, sandstones, limestones, marbles and serpentinites) have been sampled for isotope analyses of C, O, H, He, Ne, Ar, Sr, Nd, and Pb.
Date: July 1, 1998
Creator: Pili, E.; Kennedy, B.M.; Conrad, S.M.; Gratier, J.-P. & Poitrasson, F.
Partner: UNT Libraries Government Documents Department

Geologic and Engineering Characterization of East Ford Field, Reeves County, Texas

Description: The objective of this Class III 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 geologically based field development. The project focused on reservoir characterization of the East Ford unit, a representative Delaware Mountain Group field that produces from the upper Bell Canyon Formation (Ramsey Sandstone). The field, discovered in 1960, is operated by Oral Petco, Inc., as the East Ford unit: it contained an estimated 18.4 million barrels (MMbbl) of original oil in place.
Date: August 16, 1999
Creator: Dutton, Shirley P.; Flanders, William A.; Guzman, Jose I. & Zirczy, Helena
Partner: UNT Libraries Government Documents Department

Strategies for reservoir characterization and identification of incremental recovery opportunities in mature reservoirs in Frio Fluvial-Deltaic sandstones, south Texas: An example from Rincon Field, Starr County. Topical report

Description: Fluvial-deltaic sandstone reservoirs in the United States are being abandoned at high rates, yet they still contain more than 34 billion barrels of unrecovered oil. The mature Oligocene-age fluvial-deltaic reservoirs of the Frio Formation along the Vicksburg Fault Zone in South Texas are typical of this class in that, after more than three decades of production, they still contain 61 percent of the original mobile oil in place, or 1.6 billion barrels. This resource represents a tremendous target for advanced reservoir characterization studies that integrate geological and engineering analysis to locate untapped and incompletely drained reservoir compartments isolated by stratigraphic heterogeneities. The D and E reservoir intervals of Rincon field, Starr County, South Texas, were selected for detailed study to demonstrate the ability of advanced characterization techniques to identify reservoir compartmentalization and locate specific infield reserve-growth opportunities. Reservoir architecture, determined through high-frequency genetic stratigraphy and facies analysis, was integrated with production history and facies-based petrophysical analysis of individual flow units to identify recompletion and geologically targeted infill drilling opportunities. Estimates of original oil in place versus cumulative production in D and E reservoirs suggest that potential reserve growth exceeds 4.5 million barrels. Comparison of reservoir architecture and the distribution of completions in each flow unit indicates a large number of reserve-growth opportunities. Potential reserves can be assigned to each opportunity by constructing an Sooh map of remaining mobile oil, which is the difference between original oil in place and the volumes drained by past completions.
Date: November 1, 1995
Creator: McRae, L.; Holtz, M. & Hentz, T.
Partner: UNT Libraries Government Documents Department

The streaming potential of liquid carbon dioxide in BreaSandstone

Description: We report here, for the first time, evolution of the streaming potential coupling coefficient as liquid carbon dioxide infiltrates Berea sandstone. Using 125 Omega-m tap water, the coupling coefficient determined before and after each CO2 flood of five samples averaged approximately -30 mV/0.1 MPa. After liquid CO2 passed through the specimens displacing all mobile pore water, trapped water remained and the coupling coefficient was approximately -3 mV/0.1 MPa. A bound water limit of the coupling coefficient for liquid CO2 flow was found using an air-dried sample to be -0.02 mV/0.1 MPa. For initially water-saturated samples, bulk resistivity varied during CO2 invasion from 330 Ohm-m, to 150 Ohm-m during CO2/water mixing, to a final value of 380 Ohm-m. Results suggest that trapped and bound water control electrical conduction and the electrokinetic response. Applications include monitoring CO2 injectate in subsurface reservoirs using the self potential method.
Date: October 1, 2004
Creator: Moore, J.; Glaser, S.; Morrison, F. & Hoversten, G.M.
Partner: UNT Libraries Government Documents Department

Low temperature elastic constants and nonlinear acoustic response in rocks and complex materials

Description: The 'P-M Space' model of Guyer and McCall has some success in describing the large nonlinear effects ('slow dynamics') observed by Johnson et al. in rocks. The model uses elements which couple classical nonlinear elasticity with hysteretic components. The actual processes and scales corresponding to the model elements are not yet defined, however it is reasonable to seek energy scales by studying the low-temperature dependence of the elastic constants. We have measured qualitative elastic properties of basalt and Berea sandstone from room temperature down to 4 K using Resonant Ultrasound Spectroscopy (RUS). A simple elastic solid should show a monotonic increase in the elastic constants as temperature decreases. The basalt samples show this gross behavior but the sandstone shows a very unexpected anomalous regime between 40 K and 200 K where the elastic constants decrease with decreasing temperature. Both rocks show temperature-dependent structure in both the modulus and internal friction, and also significant hysteresis, indicating history and rate-dependent properties. This data provides insight into the time and energy scales of dynamical effects observed in sandstones.
Date: January 1, 2001
Creator: Darling, T. W. (Timothy W.); Ulrich, T. J. (Timothy J.); Johnson, P. A. (Paul A.) & Tencate, J. A. (James A.)
Partner: UNT Libraries Government Documents Department

The interplay of fractures and sedimentary architecture: Natural gas from reservoirs in the Molina sandstones, Piceance Basin, Colorado

Description: The Molina Member of the Wasatch Formation produces natural gas from several fields along the Colorado River in the Piceance Basin, northwestern Colorado. The Molina Member is a distinctive sandstone that was deposited in a unique fluvial environment of shallow-water floods. This is recorded by the dominance of plane-parallel bedding in many of the sandstones. The Molina sandstones crop out on the western edge of the basin, and have been projected into the subsurface and across the basin to correlate with thinner sandy units of the Wasatch Formation at the eastern side of the basin. Detailed study, however, has shown that the sedimentary characteristics of the type-section Molina sandstones are incompatible with a model in which the eastern sandstones are its distal facies equivalent. Rather, the eastern sandstones represent separate and unrelated sedimentary systems that prograded into the basin from nearby source-area highlands. Therefore, only the subsurface {open_quotes}Molina{close_quotes} reservoirs that are in close proximity to the western edge of the basin are continuous with the type-section sandstones. Reservoirs in the Grand Valley and Rulison gas fields were deposited in separate fluvial systems. These sandstones contain more typical fluvial sedimentary structures such as crossbeds and lateral accretion surfaces. Natural fractures play an important role in enhancing the conductivity and permeability of the Molina and related sandstones of the Wasatch Formation.
Date: March 1, 1997
Creator: Lorenz, J.C.
Partner: UNT Libraries Government Documents Department

Microscale Flow Modeling in Geologic Materials

Description: Three-dimensional imaging techniques, numerical methods for simulating flow and transport, and emergent computational architectures are combined to enable fundamental studies of fluid flow at the pore scale. High resolution reconstructions of porous media obtained using laser scanning confocal microscopy reduce sampling artifacts to sub-micron features, and simultaneously capture multiple grain length scales. However, the volumetric image data sets are extremely large, and there are significant computational challenges in utilizing this information effectively. The principal problem lies in the complexity of the geometry and the retention of this structure in numerical analyses. Lattice Boltzmann (LB) methods provide a direct means to simulate transport processes in complex geometric domains due to the unique ability to treat accurately and efficiently the multitude of discrete boundary conditions. LB methods are numerically explicit as formulated, and this characteristic is exploited through a mapping of the numerical domain to distributed computing architectures. These techniques are applied to perform single phase flow simulations in 3D data sets obtained from cores of Berea sandstone using confocal microscopy. Simulations are performed using both a purpose-built distributed processor computer and a massively parallel processer (MPP) platform.
Date: February 16, 1999
Creator: Fredrich, J.T. & O'Connor, R.M.
Partner: UNT Libraries Government Documents Department

DILUTE SURFACTANT METHODS FOR CARBONATE FORMATIONS

Description: There are many carbonate reservoirs in US (and the world) with light oil and fracture pressure below its minimum miscibility pressure (or reservoir may be naturally fractured). Many carbonate reservoirs are naturally fractured. Waterflooding is effective in fractured reservoirs, if the formation is water-wet. Many fractured carbonate reservoirs, however, are mixed-wet and recoveries with conventional methods are low (less than 10%). Thermal and miscible tertiary recovery techniques are not effective in these reservoirs. Surfactant flooding (or huff-n-puff) is the only hope, yet it was developed for sandstone reservoirs in the past. The goal of this research is to evaluate dilute (hence relatively inexpensive) surfactant methods for carbonate formations and identify conditions under which they can be effective. We have acquired field oil and core samples and field brine compositions from Marathon. We have conducted preliminary adsorption and wettability studies. Addition of Na{sub 2}CO{sub 3} decreases anionic surfactant adsorption on calcite surface. Receding contact angles increase with surfactant adsorption. Plans for the next quarter include conducting adsorption, phase behavior and wettability studies.
Date: January 1, 2003
Creator: Mohanty, Kishore K.
Partner: UNT Libraries Government Documents Department

Experimental Investigation of Relative Permeability Upscaling from the Micro-Scale to the Macro-Scale

Description: During this reporting period, shown experimentally that the optical coherence imaging system can acquire information on grain interfaces and void shape for a maximum depth of half a millimeter into sandstone. The measurement of interfacial area per volume (IAV), capillary pressure and saturation in two dimensional micro-models structures has shown the existence of a unique relationship among these hydraulic parameters for different pore geometry. The measurement of interfacial area per volume on a three-dimensional natural sample, i.e., sandstone, has shown the homogeneity of IAV with depth in a sample when the fluids are in equilibrium.
Date: January 29, 2003
Creator: Pyrak-Nolte, Laura J.; Cheng, JiangTao; Yu, Ping; Giordano, Nicholas; Mustata, Mirela; Chen, Diaquam et al.
Partner: UNT Libraries Government Documents Department

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

Description: Production of gas from the Frontier Formation at 18,300 R depth in the Frewen No. 4 Deep well, eastern Green River basin (Wyoming), was uneconomic despite the presence of numerous open natural fractures. Initial production tested at 500 MCFD, but dropped from 360 MCFD to 140 MCFD during a 10-day production test, and the well was abandoned. Examination of the fractures in the core suggests several probable reasons for this poor production. One factor is the presence of a hydrocarbon residue (carbon) which filled much of the porosity left in the smaller fractures after mineralization. An equally important factor is probably the reorientation of the in situ horizontal compressive stress to a trend normal to the main fractures, and which now acts to close fracture apertures rapidly during reservoir drawdown. This data set has unpleasant implications for the search for similar, deep fractured reservoirs.
Date: November 1, 1996
Creator: Lorenz, J.C.; Billingsley, R.L. & Evans, L.W.
Partner: UNT Libraries Government Documents Department

Nonlinear interaction of plane elastic waves

Description: The paper presents basic first order results of nonlinear elastic theory by Murnaghan for elastic wave propagation in isotropic solids. The authors especially address the problem of resonant scattering of two collimated beams and present analytical solutions for amplitudes of all possible types of resonant interactions for elastic plane waves. For estimation of nonlinear scattered waves they use measured elastic parameters for sandstone. The most profound nonlinear effect is expected for interactions of two SH waves generating compressional P wave at sum frequency. Estimations show that nonlinear phenomena is likely to be observed in seismic data. Basic equations of nonlinear five-constant theory by Murnaghan are also presented.
Date: June 1, 1998
Creator: Korneev, V.A.; Nihei, K.T. & Myer, L.R.
Partner: UNT Libraries Government Documents Department

Microseismic monitoring of the B-sand hydraulic fracture experiment at the DOE/GRI multi-site project

Description: Six hydraulic-fracture injections into a fluvial sandstone at a depth of 4500 ft were monitored with multi-level triaxial seismic receivers in two wells, resulting in maps of the growth and final geometry of each fracture based upon microseismic activity. These diagnostic images show that the hydraulic fractures are highly contained for smaller-volume KCl-water injections, but height growth is significant for the larger-volume, higher-rate, higher-viscosity treatments. Fracture lengths for most injections are similar. Final results are also compared with fracture models.
Date: November 1996
Creator: Warpinski, N. R.; Wright, T. B.; Peterson, R. E. & Branagan, P. T.
Partner: UNT Libraries Government Documents Department

Geological and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic reservoir. Deliverable 2.5.4, Ferron Sandstone lithologic strip logs, Emergy & Sevier Counties, Utah: Volume I

Description: Strip logs for 491 wells were produced from a digital subsurface database of lithologic descriptions of the Ferron Sandstone Member of the Mancos Shale. This subsurface database covers wells from the parts of Emery and Sevier Counties in central Utah that occur between Ferron Creek on the north and Last Chance Creek on the south. The lithologic descriptions were imported into a logging software application designed for the display of stratigraphic data. Strip logs were produced at a scale of one inch equals 20 feet. The strip logs were created as part of a study by the Utah Geological Survey to develop a comprehensive, interdisciplinary, and qualitative characterization of a fluvial-deltaic reservoir using the Ferron Sandstone as a surface analogue. The study was funded by the U.S. Department of Energy (DOE) under the Geoscience/Engineering Reservoir Characterization Program.
Date: December 8, 1995
Creator: Allison, M.L.
Partner: UNT Libraries Government Documents Department

Anisotropy and spatial variation of relative permeability and lithologic character of Tensleep Sandstone reservoirs in the Bighorn and Wind River basins, Wyoming. Quarterly report, January 1, 1996--March 31, 1996

Description: Work in conjunction with Marathon Oil Company in the Oregon Basin field utilizing Formation MicroImager and Formation MicroScanner logs has been completed. Tensleep outcrops on the western side of the Bighorn Basin are not of the quality necessary to do detailed study of stratification. This made the use of borehole imaging logs, in which stratification can be recognized, particularly attractive for the western side of the Bighorn Basin. The borehole imaging logs were used to determine the dip angle and dip direction of stratification as well as to distinguish different lithologies. It is also possible to recognize erosional bounding surfaces and classify them according to a process-oriented hierarchy. Foreset and bounding surface orientation data was utilized to create bedform reconstructions in order to simulate the distribution of flow-units bounded by erosional surfaces. The bedform reconstructions indicate that the bedforms on the western side of the basin are somewhat different from those on the eastern side of the Bighorn Basin. A report has been submitted to Marathon Oil Company, the principal cost-share subcontractor. Marine dolomitic units initially identified and correlated in the Bighorn Basin have been correlated into the Wind River Basin. Gross and net sand maps have been produced for the entire upper Tensleep in the Bighorn and Wind River Basins, as well as for each of the eolian units identified in the study. These maps indicate an overall thickening of the Tensleep to the west and south. This thickening is a result of both greater subsidence to the west and south and greater differential erosion to the north and east. An article documenting the North Oregon Basin field study will appear in the Gulf Coast Society of Economic Paleontologists and Mineralogists Foundation Conference volume entitled {open_quotes}Stratigraphic Analysis Utilizing Advanced Geophysical, Wireline and Borehole Technology for Petroleum Exploration and Production{close_quotes}.
Date: April 26, 1996
Creator: Dunn, T.L.
Partner: UNT Libraries Government Documents Department

Reservoir characterization of Pennsylvanian Sandstone reservoirs. Quarterly progress report, January 1, 1991--March 31, 1991

Description: The overall objectives of this work are: (i) to investigate the importance of various qualities and quantities of data on the optimization of waterflooding performance; and (ii) to study the application of newly developed geostatistical techniques to analyze available production data to predict future proposals of infill drilling. The study will be restricted to Pennsylvanian sandstone reservoirs commonly found in Oklahoma.
Date: August 8, 1993
Creator: Kelkar, B.G.
Partner: UNT Libraries Government Documents Department

Reservoir characterization of Pennsylvanian sandstone reservoirs

Description: The overall objectives of this work are: (i) to investigate the importance of various qualities and quantities of data on the optimization of water flooding performance; and (ii) to study the application of newly developed, geostatistical techniques to analyze available production data to predict future prospects of infill drilling. Specifically to satisfy our first objective, we will study the feasibility of applying fractal geometry concepts to characterize individual formations; develop a three-dimensional conditional simulation program to define reservoir properties at various scales; establish a method to integrate the data collected at various scales including the well test and the core data; and to investigate the utility of outcrop data in describing subsurface reservoir details. To satisfy the second objective, we will investigate various techniques to utilize the production data, including initial potential and the production decline, in proposing a possible location for a future infill well. The techniques investigated will include geostatistical analyses. The study will be restricted to Pennsylvanian sandstones reservoirs commonly found in Oklahoma.
Date: March 1, 1995
Creator: Kelkar, B.G.
Partner: UNT Libraries Government Documents Department

Reservoir characterization of Pennsylvanian sandstone reservoirs. January 1-March 31, 1993

Description: The overall objectives of this work are: (i) to investigate the importance of various qualities and quantities of data on the optimization of water flooding performance; and (ii) to study the application of newly developed, geostatistical techniques to analyze available production data to predict future prospects of infill drilling. Specifically to satisfy the first objective, the authors will study the feasibility of applying fractal geometry concepts to characterize individual formations; develop a three-dimensional conditional simulation program to define reservoir properties at various scales; establish a method to integrate the data collected at various scales including the well test and the core data; and to investigate the utility of outcrop data in describing subsurface reservoir details. To satisfy the second objective, the authors will investigate various techniques to utilize the production data, including initial potential and the production decline, in proposing a possible location for a future infill well. The techniques investigated will include geostatistical analyses. The study will be restricted to Pennsylvanian sandstones reservoirs commonly found in Oklahoma.
Date: March 1, 1995
Creator: Kelkar, B.G.
Partner: UNT Libraries Government Documents Department

Nonlinear elastic wave interaction in a sandstone bar: A summary of recent pulse-mode experiments

Description: We have performed nonlinear pulse propagation experiments in a 3.8 cm diameter rod of Berea sandstone 1.8 m long at ambient conditions. Unlike earlier studies, we measured acceleration and not displacement. Moreover, we detected 2nd and 3rd harmonic growth at smaller strain amplitudes than were observed previously (10{sup {minus}7}). Harmonic growth at identical strain amplitudes has also been noted in resonance studies using the same rock type. Current measurements are underway with the rod in vacuum where the wave attenuation is less and the conditions can be carefully controlled. Ultimately, we wish to test the validity of current analytic and numerical models for nonlinear propagation in microcracked materials.
Date: March 1, 1995
Creator: Johnson, P.A.; TenCate, J.A.; Cherry, R.; McCall, K.; Van Den Abeele, K.; Kadish, A. et al.
Partner: UNT Libraries Government Documents Department

Geological and petrophysical characterization of the Ferron Sandstone for 3-D simulation of a fluvial-deltaic reservoir. Quarterly report, July 1--September 30, 1997

Description: The objective of this project is to develop a comprehensive, interdisciplinary, and quantitative characterization of a fluvial-deltaic reservoir which will allow realistic inter-well and reservoir-scale modeling to be constructed for improved oil-field development in similar reservoirs world-wide. The geological and petrophysical properties of the Cretaceous Ferron Sandstone in east-central Utah will be quantitatively determined. Both new and existing data will be integrated into a three-dimensional representation of spatial variations in porosity, storativity, and tensorial rock permeability at a scale appropriate for inter-well to regional-scale reservoir simulation. Results could improve reservoir management through proper infill and extension drilling strategies, reduction of economic risks, increased recovery from existing oil fields, and more reliable reserve calculations. Two activities continued this quarter as part of the geological and petrophysical characterization of the fluvial-deltaic Ferron Sandstone: (1) evaluation of the Ivie Creek and Willow Springs Wash case-study areas and (2) technology transfer.
Date: November 1, 1997
Creator: Allison, M.L.
Partner: UNT Libraries Government Documents Department

Reservoir characterization of Pennsylvanian sandstone reservoirs. July 1-September 30, 1992

Description: The overall objectives of this work are: (i) to investigate the importance of various qualities and quantities of data on the optimization of water flooding performance; and (ii) to study the application of newly developed, geostatistical techniques to analyze available production data to predict future prospects of infill drilling. Specifically to satisfy the first objective, the authors will study the feasibility of applying fractal geometry concepts to characterize individual formations; develop a three-dimensional conditional simulation program to define reservoir properties at various scales; establish a method to integrate the data collected at various scales including the well test and the core data; and to investigate the utility of outcrop data in describing subsurface reservoir details. To satisfy the second objective, the authors will investigate various techniques to utilize the production data, including initial potential and the production decline, in proposing a possible location for a future infill well. The techniques investigated will include geostatistical analyses. The study will be restricted to Pennsylvanian sandstones reservoirs commonly found in Oklahoma.
Date: March 1, 1995
Creator: Kelkar, B.G.
Partner: UNT Libraries Government Documents Department

A comparison of simple upscaling models with multisupport permeability data measured on a block of Berea Sandstone

Description: A specially designed minipermeameter test system, termed the Multisupport Permeameter (MSP), has been developed for direct physical investigation of permeability upscaling. The unique feature of this instrument is its ability to acquire permeability data at multiple sample supports subject to consistent boundary conditions and flow geometries. This device has been employed to physically investigate the permeability upscaling characteristics of a block of Berea Sandstone. Results reveal a number of consistent and distinct trends relating key summary statistics to changes in sample support. Comparisons are drawn between trends in the sample mean measured on the Berea Sandstone and that predicted by three theoretical upscaling models representing three common but different approaches to modeling permeability upscaling.
Date: July 1, 1997
Creator: Tidwell, V.C. & Wilson, J.L.
Partner: UNT Libraries Government Documents Department