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Characterization of non-Darcy multiphase flow in petroleum bearing formation. Final report

Description: The productive capacity of oil and gas bearing rocks depends on various parameters characterizing the flow conditions in the reservoir. Among these, the non-Darcy flow coefficient specifically plays an important role for cases involving fluid accelerations or decelerations around the well bore and in the reservoir. However, most reservoir simulators used for reservoir management assume Darcy flow, and yield misleading results causing an incorrect analysis or projection of reservoir performance. A few attempts have been made to incorporate non-Darcy effect in reservoir models but many of these lack a reliable accuracy since they use simplified correlations which ignore the effects of the variation of the fluid and formation conditions. The present study developed an accurate non-Darcy flow model that will lead to more accurate reservoir management decisions. First, a rigorous analysis and derivation of the porous media mass and momentum equations are presented considering the non-Darcy flow behavior. Second, steady-state and unsteady-state methods for simultaneous determination of relative permeability, capillary pressure, and interfacial drag during non-Darcy flow in laboratory cores are derived. This work results in several algebraic, integral, and differential interpretation methods. Third, correlations for the non-Darcy flow coefficient are investigated and improved. The study presented in this report provides new insights and formulations in the description of non-Darcy flow in oil and gas bearing formations.
Date: April 1, 1994
Creator: Evans, R. D. & Civan, F.
Partner: UNT Libraries Government Documents Department

Hydrodynamic controls on particle transport through heterogeneous porous media. Technical progress report

Description: The initial stages of this project have been focused on equipment development and preliminary experimental efforts. Among the accomplishments to date are the development of a successful flow cell design, proof of the utility of the UV resin, adjustment of the Laser Particle Counter to produce reliable readings, installation of a low particle content water supply, installation of a microscope for viewing discharge samples, development of a fiber/rod optic system for freezing the UV resin in situ and performance of initial experiments on layered and complex heterogeneities. The work is currently following very closely the original schedule for research efforts. Continuing efforts in year one will include continued efforts in simple and complex heterogeneity in two-dimensions, extension into three-dimensions, consideration of the most appropriate methods for creating geologically realistic structures in the laboratory, interaction with other SSP research programs and organization of the spring meeting on intermediate-scale experimentation to be held at Notre Dame. Efforts in year two will be focused on three-dimensional experiments in saturated media, extension of results into unsaturated media, development of techniques for unsaturated media characterization, and development of research ties with outside research interests.
Date: September 30, 1992
Creator: Silliman, S. E.
Partner: UNT Libraries Government Documents Department

Evaluation of the Impact of CO2, Aqueous Fluid, and Reservoir Rock Interactions on the Geologic Sequestration of CO2 with Special Emphasis on Economic Implications

Description: Lowering the costs of front-end processes in the geologic sequestration of CO{sub 2} can dramatically lower the overall costs. One approach is to sequester less-pure CO{sub 2} waste streams that are less expensive or require less energy to separate from flue gas, a coal gasification process, etc. The objective of this research is to evaluate the impacts of an impure CO{sub 2} waste stream on geologic sequestration using both reaction progress and reactive transport simulators. The simulators serve as numerical laboratories within which a series of computational experiments can be designed, carried out, and analyzed to quantify sensitivity of the overall injection/sequestration process to specific compositional, hydrologic, structural, thermodynamic, and kinetic parameters associated with the injection fluid and subsurface environment.
Date: March 8, 2001
Creator: Knauss, K G; Johnson, J W; Steefel, C I & Nitao, J J
Partner: UNT Libraries Government Documents Department

Field verification of CO{sub 2}-foam. Second annual report, October 1, 1990--September 30, 1991

Description: In September 1989, the Petroleum Recovery Research Center (PRRC), a division of New Mexico Institute of Mining and Technology, received a grant from the US Department of Energy (DOE) for a project entitled ``Field Verification of CO{sub 2} Foam.`` The grant provided for an extension of the PRRC laboratory work to a field testing stage to be performed in collaboration with an oil producer actively conducting a CO{sub 2} flood. The objectives of this project are to: (1) conduct reservoir studies, laboratory tests, simulation runs, and field tests to evaluate the use of foam for mobility control or fluid diversion in a New Mexico CO{sub 2} flood, and (2) evaluate the concept of CO{sub 2}-foam in the field by using a reservoir where CO{sub 2} flooding is ongoing, characterizing the reservoir, modeling the process, and monitoring performance of the field test. Seven tasks were identified for the successful completion of the project: (1) evaluate and select a field site, (2) develop an initial site- specific plan, (3) conduct laboratory CO{sub 2}-foam mobility tests, (4) perform reservoir simulations, (5) design the foam slug, (6) implement a field test, and (7) evaluate results.
Date: May 1, 1992
Creator: Martin, F. D.; Heller, J. P. & Weiss, W. W.
Partner: UNT Libraries Government Documents Department

Transient foam flow in porous media with CAT Scanner

Description: Transient behavior is likely to dominate over most of the duration of a foam injection field project. Due to the lack of date, little is presently known about transient foam flow behavior. Foam flow does not follow established models such as the Buckley-Leverett theory, and no general predictive model has been derived. Therefore, both experimental data and a foam flow theory are needed. In this work, foam was injected at a constant mass rate into one-dimensional sandpacks of 1-in diameter and 24-in or 48-in length that had initially been saturate with distilled water. The system was placed in a cat Scanner. Data, obtained at room temperature and low pressure at various times, include both the pressure and saturation distributions. Pressure profiles showed that the pressure gradient is much greater behind the foam front than ahead of it. Moreover, the pressure gradients keep changing as the foam advances in the sandpack. This behavior differs from Buckley-Leverett theory. The CT scan results demonstrated gas channeling near the front, but eventually the foam block all these channels and sweeps the entire cross section after many pore volumes of injection. Three series of experiments were run: (1) surfactant adsorption measurements; (2) gas displacements of surfactant-laden solutions and (3) foam displacements. The first two series of experiments were made to provide the necessary parameters required to match the foam displacements. To this end, it was necessary to smooth the saturation history data, using a Langmuir-type formula. A theory was proposed based on the principles of the fractional flow curve construction method. This foam theory treats the foam as composed of infinitesimal slugs of gas of varying viscosities. The foam front has the lowest viscosity and foam at the injection end has the highest.
Date: March 1, 1992
Creator: Liu, Dianbin & Brigham, W. E.
Partner: UNT Libraries Government Documents Department

Drawdown behavior of gravity drainage wells

Description: An analytical solution for drawdown in gravity drainage wells is developed. The free-surface flow is viewed as incompressible, and anisotropy effects are included. The well is a line source well, and the reservoir is infinitely large. The model is valid for small drawdowns. The uniform wellbore potential inner boundary condition is modelled using the proper Green`s function. The discontinuity at the wellbore is solved by introducing a finite skin radius, and the formulation produces a seepage face. The calculated wellbore flux distribution and wellbore pressures are in fair agreement with results obtained using a numerical gravity drainage simulator. Three distinct flow periods are observed. The wellbore storage period is caused by the moving liquid level, and the duration is short. During the long intermediate flow period, the wellbore pressure is nearly constant. In this period the free surface moves downwards, and the liquid is produced mainly by vertical drainage. At long times the semilog straight line appears. The confined liquid solutions by Theis (1935) and van Everdingen and Hurst (1949) may be used during the pseudoradial flow period if the flowrate is low. New type curves are presented that yield both vertical and horizontal permeabilities.
Date: October 1, 1993
Creator: Aasen, J. A. & Ramey, H. J. Jr.
Partner: UNT Libraries Government Documents Department

Energy flux and hydrogeology of thermal anomalies in the Gulf of Mexico basin. Progress report, June 1992--August 1993

Description: Specific project objectives are to: determine whether or not the observed thermal anomalies in the Gulf of Mexico sedimentary basin can be accounted for by heat conduction only; determine whether or not the present-day groundwater flow system is amenable with the heat advection hypothesis; and determine fluid and heat flux histories that are consistent with the observed data. In support of these objectives, we have collected over 25,000 data points, reflecting pressures and temperatures at depths of up to 16,000 feet in the Texas portion of the Gulf of Mexico basin. These data have been collated into a computerized data base system. In addition, we have begun collection of thermophysical data. This research provides fundamental knowledge and understanding to the geosciences and contributes to the sciences and technology base required for current and future energy technologies. Quantifying the evolution of the hydrodynamic and thermal regimes in sedimentary basins is important for predicting timing of hydrocarbon maturation and migration. The evolving subsurface temperature and hydrodynamic system also have a first-order control on sediment diagenesis, brine evolution, and the formation of ore deposits.
Date: September 1, 1993
Creator: Sharp, J. M. Jr.
Partner: UNT Libraries Government Documents Department

Productivity and injectivity of horizontal wells. Quarterly report, April 1--June 30, 1996

Description: A number of activities have been carried out during this quarter of research. A list outlining these efforts is presented including: (1) The design and planning of the next phase of the two-phase flow experiments have moved forward. The necessary modifications to allow the use of wire-wrapped screens have been made. The flow loop and the data acquisition system are currently being tested and the new experiments are about to commence. (2) Work on obtaining exact well models for a horizontal well or a well of any general profile has continued. (3) Work on the application of horizontal wells in gas condensate reservoirs has progressed. The available methods and models are being critically evaluated with the aid of simulation runs. (4) Research work on developing coarse grid methods to study cresting in horizontal wells has continued. Correlations for optimum grid size, breakthrough time, and post breakthrough behavior (i.e. water-oil ratio) are being developed and tested for the problem of water cresting. (5) The Ph.D. project on three-dimensional flexible grid simulator (FLEX) was successfully defended in June. The FLEX simulator will be used in future studies as well as in future developments. The dissertation report will be submitted soon to the US DOE. This quarterly report is based on the last activity listed above. It shows the advantage of the new flexible grid simulator.
Date: August 1, 1996
Creator: Aziz, K. & Hewett, T.A.
Partner: UNT Libraries Government Documents Department

Improved efficiency of miscible CO{sub 2} floods and enhanced prospects for CO{sub 2} flooding heterogeneous reservoirs. Quarterly technical progress report, October 1--December 31, 1996

Description: Progress has been made in each of the three project areas during this quarter. Each quarter the authors highlight one project area. This quarter, Task 1 is being highlighted with expanded details. In Task 1, a foam-durability apparatus was used to evaluate surfactant and foam properties (interfacial tension (IFT) of surfactant solution with dense CO{sub 2}, the critical micelle concentration, foaming ability of the mixture and foam stability) at high pressure condition. These data were correlated with the dynamic properties of foam measured in coreflooding experiments. For the five surfactants tested the results show that effectiveness of mobility reduction of foam in porous media is strongly correlated with the stability of foam in the bulk phase and the mobility reduction factor increases with the reduction of IFT. During this quarter in Task 2 a new series of core flood tests was completed, that measured the effects of CO{sub 2} flow fraction and rock permeability on foam-flow behavior. Also, an apparatus was designed, built, and tested under reservoir conditions that measures volume and composition of CO{sub 2} hydrocarbon extractable components. In Task 3 this quarter, a core was prepared to aid in the determination of the effect of water saturation on the efficiency of CO{sub 2} gravity drainage.
Date: March 1, 1997
Creator: Grigg, R.B. & Schechter, D.S.
Partner: UNT Libraries Government Documents Department

A novel approach to modeling unstable BOR displacements. Annual report, August 1991--September 1992

Description: This research is aimed at developing a methodology for predicting the performance of unstable displacements in heterogeneous reservoirs. A performance prediction approach that combines numerical modeling with laboratory imaging experiments is being developed. Flow visualization experiments are being performed on laboratory corefloods using X-ray computed tomography (CT) and other imaging technologies to map the insitu fluid saturations in time and space. A systematic procedure is being developed to replicate the experimental image data with high-resolution numerical models of the displacements. The wall-tuned numerical models will then be used to scale the results of the laboratory coreflood experiments to heterogeneous reservoirs in order to predict the performance of unstable displacements in such reservoirs. Accomplishments for the year are presented for the following tasks: flow visualization experiments with CT scanner; flow visualization experiments with imaging workstation; model development and testing; and history match of the flow visualization experiments.
Date: December 31, 1992
Creator: Peters, E.J.
Partner: UNT Libraries Government Documents Department

Computed microtomography of reservoir core samples

Description: X-ray computed tomography (CT) is often utilized to evaluate and characterize structural characteristics within reservoir core material systems. Generally, medical CT scanners have been employed because of their availability and ease of use. Of interest lately has been the acquisition of three-dimensional, high resolution descriptions of rock and pore structures for characterization of the porous media and for modeling of single and multiphase transport processes. The spatial resolution of current medical CT scanners is too coarse for pore level imaging of most core samples. Recently developed high resolution computed microtomography (CMT) using synchrotron X-ray sources is analogous to conventional medical CT scanning and provides the ability to obtain three-dimensional images of specimens with a spatial resolution on the order of micrometers. Application of this technique to the study of core samples provides two- and three-dimensional high resolution description of pore structure and mineral distributions. Pore space and interconnectivity is accurately characterized and visualized. Computed microtomography data can serve as input into pore-level simulation techniques. A generalized explanation of the technique is provided, with comparison to conventional CT scanning techniques and results. Computed microtomographic results of several sandstone samples are presented and discussed. Bulk porosity values and mineralogical identification were obtained from the microtomograms and compared with gas porosity and scanning electron microscope results on tandem samples.
Date: March 1, 1995
Creator: Coles, M.E.; Muegge, E.L.; Spanne, P. & Jones, K.W.
Partner: UNT Libraries Government Documents Department

The impact of high-frequency sedimentation cycles on stratigraphic interpretation

Description: Global cyclostratigraphy, a methodology that utilizes climate change to evaluate sediment flux, characterizes the impact of sediment cycles on stratigraphy. Climatic succession, sediment yield cycles, and the phase relationship of sediment cycles to eustatic cycles are all determined in the early stages of basin analysis. Sedimentologic information is then used to assist in sequence evaluations. Climatic successions are intrinsically associated with global position (paleogeography) and are not necessarily synchronous with glacioeustatic sea-level cycles. A preliminary evaluation of the effect of climate on sediment supply from modem river systems indicates that sediment yield may vary by well over two orders of magnitude during one climate cycle. Consequently, basins in different climatic belts can have distinctly different volumes and lithologies for systems tracts that have similar base-level changes. The stratigraphic computer program Sedpak was utilized to examine the possible impact of different sedimentation cycles on sequence interpretation and reservoir forecasts. The effect of sedimentation cycles on reservoir distribution in real world sequences is demonstrated with a comparison of the Miocene section of the Surma basin, Bangladesh, and the Plio-Pleistocene section of the Gulf of Mexico. In the Surma basin, reservoirs are most likely to occur in transgressive and highstand systems tracts, while reservoirs in the Gulf of Mexico are more likely in lowstand prograding complexes.
Date: January 1, 1997
Creator: Perlmutter, M.A.; Radovich, B.J. & Matthews, M.D.
Partner: UNT Libraries Government Documents Department

Natural fracture characterization using passive seismic illumination

Description: The presence of natural fractures in reservoir rock can significantly enhance gas production, especially in tight gas formations. Any general knowledge of the existence, location, orientation, spatial density, and connectivity of natural fractures, as well as general reservoir structure, that can be obtained prior to active seismic acquisition and drilling can be exploited to identify key areas for subsequent higher resolution active seismic imaging. Current practices for estimating fracture properties before the acquisition of surface seismic data are usually based on the assumed geology and tectonics of the region, and empirical or fracture mechanics-based relationships between stratigraphic curvature and fracturing. The objective of this research is to investigate the potential of multicomponent surface sensor arrays, and passive seismic sources in the form of local earthquakes to identify and characterize potential fractured gas reservoirs located near seismically active regions. To assess the feasibility of passive seismic fracture detection and characterization, we have developed numerical codes for modeling elastic wave propagation in reservoir structures containing multiple, finite-length fractures. This article describes our efforts to determine the conditions for favorable excitation of fracture converted waves, and to develop an imaging method that can be used to locate and characterize fractures using multicomponent, passive seismic data recorded on a surface array.
Date: January 8, 2003
Creator: Nihei, K.T.
Partner: UNT Libraries Government Documents Department

ACOUSTICAL IMAGING AND MECHANICAL PROPERTIES OF SOFT ROCK AND MARINE SEDIMENTS

Description: During this phase of the project the research team concentrated on acquisition of acoustic emission data from the high porosity rock samples. The initial experiments indicated that the acoustic emission activity from high porosity Danian chalk were of a very low amplitude. Even though the sample underwent yielding and significant plastic deformation the sample did not generate significant AE activity. This was somewhat surprising. These initial results call into question the validity of attempting to locate AE activity in this weak rock type. As a result the testing program was slightly altered to include measuring the acoustic emission activity from many of the rock types listed in the research program. The preliminary experimental results indicate that AE activity in the sandstones is much higher than in the carbonate rocks (i.e., the chalks and limestones). This observation may be particularly important for planning microseismic imaging of reservoir rocks in the field environment. The preliminary results suggest that microseismic imaging of reservoir rock from acoustic emission activity generated from matrix deformation (during compaction and subsidence) would be extremely difficult to accomplish.
Date: January 31, 2001
Creator: Thurman E. Scott, Jr., Ph.D.; Younane Abousleiman, Ph.D. & Musharraf Zaman, Ph.D., P.E.
Partner: UNT Libraries Government Documents Department

Pore level visualization of foam flow in a silicon micromodel. SUPRI TR 100

Description: This paper is concerned with the behavior of foam in porous media at the pore level. Identical, heterogeneous silicon micromodels, two dimensionally etched to replicate flow in Berea Sandstone, were used. The models, already saturated with varying concentrations of surfactant and, at times, oil were invaded with air. Visual observations were made of these air displacement events in an effort to determine foam flow characteristics with varying surfactant concentrations, and differing surfactants in the presence of oil. These displacement events were recorded on video tape. These tapes are available at the Stanford University Petroleum Research Institute, Stanford, California. The observed air flow characteristics can be broadly classified into two: continuous and discontinuous. Continuous air flow was observed in two phase runs when the micromodel contained no aqueous surfactant solution. Air followed a tortuous path to the outlet, splitting and reconnecting around grains, isolating water located in dead-end or circumvented pores, all without breaking and forming bubbles. No foam was created. Discontinuous air flow occurred in runs containing surfactant - with smaller bubble sizes appearing with higher surfactant concentrations. Air moved through the medium by way of modified bubble train flow where bubbles travel through pore throats and tend to reside more statically in larger pore bodies until enough force is applied to move them along. The lamellae were stable, and breaking and reforming events by liquid drainage and corner flow were observed in higher surfactant concentrations. However, the classic snap-off process, as described by Roof (1973) was not seen at all.
Date: January 1, 1996
Creator: Woody, F.; Blunt, M. & Castanier, L.
Partner: UNT Libraries Government Documents Department

Increasing heavy oil reserves in the Wilmington oil field through advanced reservoir characterization and thermal production technologies. Quarterly progress report, July 1, 1995--September 30, 1995

Description: This project involves improving thermal recovery techniques in a slope and basin clastic (SBC) reservoir in the Wilmington field, Los Angeles, California. Advanced technologies to be employed include the development of 3-D geologic models, 3-D thermal reservoir well stimulation models, computerized 3-D visualizations of the geologic and reservoir simulation models, a detailed study of the geochemistry and rock-fluid interactions and studies of steam completion techniques.
Date: December 4, 1995
Creator: Hara, S.
Partner: UNT Libraries Government Documents Department

Naturally fractured tight gas reservoir detection optimization. Quarterly report, July--September 1995

Description: During the third quarter, processing continued at Western Geophysical. The processing was closely monitored by Palantir and Blackhawk Geosciences. Early in the processing Palantir determined that the original DMO velocities from the combined data volume were inadequate for performing the azimuthally split DMO. A series of DMO velocity scans were therefore run on each of the data sets and new velocities picked using two work stations simultaneously. This ensured uniform picking throughout the two volumes. DMO on the separated volumes and final migration demonstrated results that showed significantly clearer reflections than the total (all Azimuth) volume for certain intervals. A difference in the two velocity fields showed that the E-W data volume is consistently higher in velocity than the N-S data volume. This result would correspond to dominant, open E-W fractures at depth. This report also reviews the states of data acquisition and seismic source drilling and placement. It documents the shothole drilling design, layout, and detector placement.
Date: December 1, 1995
Partner: UNT Libraries Government Documents Department

Coupled transport and chemical interactions in petroleum reservoirs: Multicomponent tracer demonstration large scale application

Description: This is the final report for a two-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Enhanced tracer approaches for characterization of oil reservoirs were demonstrated and evaluated for both transport and chemical interactions. Existing tracer technology is limited in numbers of tracers and relies heavily on radioactive species. Using expertise developed at Los Alamos through applications of chemical, analytical, and geologic techniques to testing, alternative energy and environmental programs, we have defined new classes of conservative and reactive non-radioactive tracers for both laboratory and field experiments. Reservoir experiments are critical to improved reservoir management, characterization of CO{sub 2} flooding, and validation/development of significantly enhanced simulators utilizing advanced computational technology. A demonstration field tracer experiment has been performed in the Salt Creek Field Unit in West Texas to characterize a section of the reservoir under water-flood. An initial robust set of tracers, field experience in their application, and interpretation methodology was demonstrated for large scale multi-well, multi-tracer flow and connectivity tests.
Date: July 1, 1996
Creator: Janecky, D.R.; Spall, W.D.; Sandoval, W. & Williams, S.
Partner: UNT Libraries Government Documents Department

Advanced oil recovery technologies for improved recovery from slope basin clastic reservoirs, Nash Draw Brushy Canyon Pool, Eddy County, NM. Quarterly technical progress report, April 1, 1996--June 30, 1996

Description: The overall objective of this project is to demonstrate that a development program based on advanced reservoir management methods can significantly improve oil recovery. The demonstration plan includes developing a control area using standard reservoir management techniques and comparing the performance of the control area with an area developed using advanced reservoir management methods. Specific goals to attain the objective are: (1) to demonstrate that a development drilling program and pressure maintenance program, based on advanced reservoir management methods, can significantly improve oil recovery compared with existing technology applications, and (2) to transfer the advanced methodologies to oil and gas producers in the Permian Basin and elsewhere in the U.S. oil and gas industry.
Date: July 26, 1996
Creator: Murphy, M.B.
Partner: UNT Libraries Government Documents Department

Evaluation of a downhole tiltmeter array for monitoring hydraulic fractures

Description: A series of hydraulic-fracture experiments using a downhole tiltmeter array, called an inclinometer array, was conducted at the Department of Energy (DOE)/Gas Research Institute (GRI) Multi-Site facility in Colorado. The inclinometer array was used to measure the deformation of the reservoir rock in response to hydraulic fracture opening and confirm microseismically measured results. In addition, the inclinometer array was found to be a useful tool for accurately measuring closure stress, measuring residual widths of both propped and unpropped fractures, estimating proppant distribution, and evaluating values of in situ moduli.
Date: March 1, 1997
Creator: Warpinski, N.R.; Engler, B.P.; Branagan, P.T.; Wilmer, R. & Wolhart, S.L.
Partner: UNT Libraries Government Documents Department

Three-dimensional geomechanical simulation of reservoir compaction and implications for well failures in the Belridge diatomite

Description: This paper describes an integrated geomechanics analysis of well casing damage induced by compaction of the diatomite reservoir at the Belridge Field, California. Historical data from the five field operators were compiled and analyzed to determine correlations between production, injection, subsidence, and well failures. The results of this analysis were used to develop a three-dimensional geomechanical model of South Belridge, Section 33 to examine the diatomite reservoir and overburden response to production and injection at the interwell scale and to evaluate potential well failure mechanisms. The time-dependent reservoir pressure field was derived from a three-dimensional finite difference reservoir simulation and used as input to three-dimensional non-linear finite element geomechanical simulations. The reservoir simulation included -200 wells and covered 18 years of production and injection. The geomechanical simulation contained 437,100 nodes and 374,130 elements with the overburden and reservoir discretized into 13 layers with independent material properties. The results reveal the evolution of the subsurface stress and displacement fields with production and injection and suggest strategies for reducing the occurrence of well casing damage.
Date: November 1996
Creator: Fredrich, J. T.; Argueello, J. G.; Thorne, B. J. & Wawersik, W. R.
Partner: UNT Libraries Government Documents Department

Nonlinear least squares and regularization

Description: A problem frequently encountered in the earth sciences requires deducing physical parameters of the system of interest from measurements of some other (hopefully) closely related physical quantity. The obvious example in seismology (either surface reflection seismology or crosswell seismic tomography) is the use of measurements of sound wave traveltime to deduce wavespeed distribution in the earth and then subsequently to infer the values of other physical quantities of interest such as porosity, water or oil saturation, permeability, etc. The author presents and discusses some general ideas about iterative nonlinear output least-squares methods. The main result is that, if it is possible to do forward modeling on a physical problem in a way that permits the output (i.e., the predicted values of some physical parameter that could be measured) and the first derivative of the same output with respect to the model parameters (whatever they may be) to be calculated numerically, then it is possible (at least in principle) to solve the inverse problem using the method described. The main trick learned in this analysis comes from the realization that the steps in the model updates may have to be quite small in some cases for the implied guarantees of convergence to be realized.
Date: April 1, 1996
Creator: Berryman, J.G.
Partner: UNT Libraries Government Documents Department

Integration of advanced geoscience and engineering techniques to quantify interwell heterogeneity. Quarterly technical report, April 1, 1996--June 30, 1996

Description: The objective of this project is to integrate advanced geoscience and reservoir engineering concepts with the goal of quantifying the dynamics of fluid-rock and fluid-fluid interactions as they relate reservoir architecture and lithologic characterization. This interdisciplinary effort will integrate geological and geophysical data with engineering and petrophysical results through reservoir simulation. Subcontractors from Stanford University and the University of Texas at Austin are collaborating on the project. Several members of the Petroleum Recovery Research Center are participating in the development of the 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. Technical progress is summarized for geologic studies and field operations at Sulimar Queen Field, New Mexico, and technology transfer from this study.
Date: October 1, 1996
Creator: Buckley, J.S. & Ouenes, A.
Partner: UNT Libraries Government Documents Department

Gypsy Field project in reservoir characterization. Quarterly report, April 1, 1996--June 30, 1996

Description: The overall objective of this project is to use the extensive Gypsy Field laboratory and data set as a focus for developing and testing reservoir characterization methods that are targeted at improved recovery of conventional oil. The Gypsy Field laboratory, as described by Doyle, O`Meara, and Witterholt, consists of coupled outcrop and subsurface sites which have been characterized to a degree of detail not possible in a production operation. Data from these sites entail geological descriptions, core measurements, well logs, vertical seismic surveys, a 3D seismic survey, crosswell seismic surveys, and pressure transient well tests.
Date: November 1, 1996
Creator: O`Meara, D.J. Jr.
Partner: UNT Libraries Government Documents Department