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Prediction of Gas Injection Performance for Heterogeneous Reservoirs

Description: 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.
Date: May 17, 1999
Creator: Blunt, Martin J. & Orr, Franklin M.
Partner: UNT Libraries Government Documents Department

Topical Report: Task 2.2 "Pressure Transmissibility"

Description: The rate and amplitude of pressure transmission of various drilling fluids--particularly aphron drilling fluids--are measured in a long conduit and in sand packs to determine how pressure transmissibility can affect fluid invasion.
Date: July 30, 2004
Creator: Belkin, Arkadiy & Growcock, Fred
Partner: UNT Libraries Government Documents Department

Design and Implementation of a C02 Flood Utilizing Advanced Reservoir Characterization and Horizontal Injection Wells in a Shallow Carbonate Approaching Waterflood Depletion

Description: The first project objective is to utilize reservoir characterization and advanced technologies to optimize the design of a carbon dioxide (CO2) project for the South Cowden Unit (SCU) located in Ector County, Texas. The SCU is a mature, relatively small, shallow shelf carbonate unit nearing waterflood depletion. The second project objective is to demonstrate the performance and economic viability of the project in the field. All work during the fourth quarter falls within the demonstration project.
Date: April 28, 1998
Creator: Bles, J. Scott & Dollens, Kimberly B.
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

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

Improved efficiency of miscible CO{sub 2} floods and enhanced prospects for CO{sub 2} flooding heterogeneous reservoirs. Quarterly technical progress report, April 1, 1996--June 30, 1996

Description: Progress has been made in each of the three project areas during this quarter. Each quarter we are highlighting one project area. This quarter, Task 2 is highlighted with expanded details. Significant progress has been made this quarter in testing the functionalities of the foam-durability apparatus for assessment of foam properties at reservoir conditions. Another surfactant, Alipal{reg_sign} CD-128 at a concentration of 1000 ppm, was used for core flooding experiments. The foam mobility data showed a significant reduction of CO{sub 2} mobility and a favorable mobility dependence on rock permeability. Two slim tube test series and continuous phase equilibrium were done to examine the effects of pressure, temperature, and oil composition on oil displacement efficiency. A new series of core foam tests were completed to study the effects of flow rate, CO{sub 2} fraction (foam) quality, and rock permeability on foam-flow behavior. We are in the process of moving the foam reservoir simulator MASTER from a workstation to a Pentium PC environment and test MASTER on a 166 MHz Pentium PC. IFT of CO{sub 2}/crude oil has been measured using our pendant drop measurement system at 138{degrees}F and pressures from 850 psig to 2200 psig. The CO{sub 2} gravity drainage experiment that is in progress using a 50md Berea core at 138{degrees}F and pressures from 1700 to 2000 psig has reached 48% oil recovery and is continuing to increase. The mathematical model developed previously matches the experimental response accurately.
Date: July 20, 1996
Creator: Schechter, D.S.
Partner: UNT Libraries Government Documents Department

Advanced reservoir characterization and evaluation of CO{sub 2} gravity drainage in the naturally fractured Spraberry reservoir. Quarterly technical report, April 1, 1996--June 30, 1996

Description: Progress has been made in the area of laboratory analysis of Spraberry oil/brine/rock interactions during this quarter. Water imbibition experiments were conducted under ambient conditions, using cleaned Spraberry cores, synthetic Spraberry reservoir brine, and Spraberry oil. It has been concluded that the Spraberry reservoir cores are weakly water-wet. The average Amott wettability index to water is about 0.55. The average oil recovery due to spontaneous water imbibition is about 50% of original oil in place.
Date: November 1, 1996
Creator: Schechter, D.
Partner: UNT Libraries Government Documents Department

Research on oil recovery mechanisms in heavy oil reservoirs. Final report

Description: The Research on Heavy Oil Recovery Mechanisms at Stanford University has been ongoing for the past twenty years. During this span of time, 106 technical reports have been published by the Department of Energy, over 200 technical papers have been presented at meetings of professional societies, and most importantly, over 120 students have performed research as graduate research assistants and are now employed by the oil industry or research institutions. Funding was provided by the Department of Energy and also by a group of oil companies. The support of industry is very important to us, not only from the financial viewpoint, but also from the constant exchange of ideas with technical experts from the companies. Meetings are held yearly with industry representatives and informal exchange of information is constant. Support from industry has been steady since 1980. SUPRI personnel is also active in participating in technical meetings and seminars organized by technical societies and other research organizations. We strongly believe that information exchange is one of the most cost effective way to improve research.
Date: August 1, 1996
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

Economic recovery of oil trapped at fan margins using high angle wells and multiple hydraulic fractures. Quarterly report, April 1, 1996--June 30, 1996

Description: This project attempts to demonstrate the effectiveness of exploiting thin-layered, low-energy deposits at the distal margin of a prograding turbidite complex through the use of hydraulically-fractured, horizontal or high-angle wells. The combination of a horizontal or high-angle well and hydraulic fracturing will allow greater pay exposure than can be achieved with conventional vertical wells while maintaining vertical communication between thin interbedded layers and the wellbore. A high-angle well will be drilled in the fan margin portion of a slope-basin clastic reservoir and will be completed with multiple hydraulic-fracture treatments. Geologic modeling, reservoir characterization, and fine-grid reservoir simulation will be used to select the well location and orientation. Design parameters for the hydraulic fracture treatments will be determined by fracturing an existing test well. Fracture azimuth will be predicted, in part, by passive seismic monitoring from an offset well during fracture stimulation of the test well.
Date: July 29, 1996
Creator: Niemeyer, B.L.
Partner: UNT Libraries Government Documents Department

Audio-magnetotelluric data collected in the area of Beatty, Nevada

Description: In the summer of 1997, electrical geophysical data was collected north of Beatty, Nevada. Audio-magnetotellurics (AMT) was the geophysical method used to collect 16 stations along two profiles. The purpose of this data collection was to determine the depth to the alluvial basement, based upon the needs of the geologists requesting the data.
Date: November 1, 1998
Creator: Williams, J.M.
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

Identifying structures in clouds of induced microseismic events

Description: A method for finding improved relative locations of microearthquakes accompanying fluid production and injection is presented. The method is based on the assumption that the microearthquake locations are more clustered than found when events are located using conventional techniques. By allowing the rms misfit between measured arrival times and predicted arrival times to increase if events move closer together, the authors find that there is more structure in the pattern of seismic locations. The method is demonstrated using a dataset of microearthquakes induced by hydraulic fracturing. The authors find that structures found using relative arrival times of events having similar waveforms to find improved relative locations of events can also be recovered using the new inversion method but without the laborious repicking procedure. The method provides improved relative locations and hence, an improved image of the structure within the seismic zone that may allow for a better relation between microearthquake locations and zones of increased fluid permeability to be found.
Date: July 1, 1997
Creator: Fehler, M.; House, L. & Phillips, W.S.
Partner: UNT Libraries Government Documents Department

Integrated approach towards the application of horizontal wells to improve waterflooding performance. Quarterly report, July 1, 1996--September 30, 1996

Description: The overall purpose of the proposed project is to improve secondary recovery performance of a marginal oil field through the use of an appropriate reservoir management plan. The selection of plan will be based on the detailed reservoir description using an integrated approach. We expect that 2 to 5% of the original oil in place will be recovered using this method. This should extend the life of the reservoir by at least 10 years. The project is divided into two stages. In Stage I of the project, we selected part of the Glenn Pool field - Self Unit. We conducted cross bore hole tomography surveys and formation micro scanner logs through a newly drilled well. By combining the state-of-the-art data with conventional core and log data, we developed a detailed reservoir description based on an integrated approach. After conducting extensive reservoir simulation studies, we evaluated alternate reservoir management strategies to improve the reservoir performance including drilling of a horizontal injection well. We observed that selective completion of many wells followed by an increase in the injection rate was the most feasible option to improve the performance of the Self Unit. This management plan is currently being implemented and the performance is being monitored.
Date: December 31, 1996
Creator: Kelkar, B.G.
Partner: UNT Libraries Government Documents Department

Increasing waterflood reserves in the Wilmington oil field through improved reservoir characterization and reservoir management. Quarterly report, July 1, 1996--September 30, 1996

Description: The objectives of this quarterly report are to summarize the work conducted under each task during the reporting period July - September 1996, and to report all technical data and findings as specified in the {open_quotes}Federal Assistance Reporting Checklist{close_quotes}. The main objective of this project is the transfer of technologies, methodologies, and findings developed and applied in this project to other operators of Slope and Basin Clastic Reservoirs. This project will study methods to identify sands with high remaining oil saturation and to recomplete existing wells using advanced completion technology. The identification of the sands with high remaining oil saturation will be accomplished by developing a deterministic three dimensional (3-D) geologic model and by using a state of the art reservoir management computer software. The wells identified by the geologic and reservoir engineering work as having the best potential will be logged with a pulsed acoustic cased-hole logging tool. The application of the logging tools will be optimized in the lab by developing a rock-log model. This rock-log model will allow us to convert shear wave velocity measured through casing into effective porosity and hydrocarbon saturation. The wells that are shown to have the best oil production potential will be recompleted. The recompletions will be optimized by evaluating short radius and ultra-short radius lateral recompletions as well as other techniques.
Date: October 28, 1996
Creator: Walker, S.
Partner: UNT Libraries Government Documents Department

Water films, asphaltenes, and wettability alteration

Description: We present a transport model for asphaltene diffusion from an oil/water interface through a water film followed by adsorption at a solid/water interface. Using a Langmuir adsorption isotherm, the effect of asphaltene aqueous solubility and adsorption constant K on equilibration time are established. For K greater than 1 nm and asphaltene solubilities down to 0.1 ppb, adsorption equilibrium, taken to be 1 mg/m{sup 2}, occurs within a few hours. Negligible asphaltene solubility does not explain why a water film prevents asphaltene adsorption and wettability alteration in reservoir rock.
Date: June 1, 1998
Creator: Kaminsky, R. & Radke, C.J.
Partner: UNT Libraries Government Documents Department

Porosity and Permeability Evolution Accompanying Hot fluid Injection into Diatomite, SUPRI TR-123

Description: An experimental study of silica dissolution was performed to probe the evolution of permeability and porosity in siliceous diatomite during hot fluid injection such as water or steam flooding. Two competing mechanisms were identified. Silica solubility in water at elevated temperature causes rock dissolution thereby increasing permeability; however, the rock is mechanically weak leading to compressing of the solid matrix during injection. Permeability and porosity can decrease at the onset of fluid flow. A laboratory flow apparatus was designed and built to examine these processes in diatomite core samples.
Date: April 19, 2001
Creator: Diabira, I.; Castanier, L.M. & Kovscek, A.R.
Partner: UNT Libraries Government Documents Department

Integrated Outcrop and Subsurface Studies of the Interwell Environment of Carbonate Reservoirs: Clear Fork (Leonaradian Age) Reservoirs, West Texas and New Mexico, Semi-Annual

Description: Outcrop studies include stratigraphic and petrophysical analysis. Analysis of the detailed sequence- and cycle-scale architecture of the Clear Fork reservoir-equivalent outcrops in Apache Canyon is nearly complete. This work reveals two high-frequency transgressive-regressive sequences (HFS) in the lower Clear Fork composite depositional sequence and three HFS in the basal middle Clear Fork composite depositional sequence. A 1,800-ft transect of 1-inch-diameter samples was collected from one cycle at the Apache Canyon outcrop. The transect was sampled with 5-ft spacing, but there were some gaps due to cover and cliff, resulting in 181 samples. Permeability, porosity, and grain density were measured, and the spatial statistics are being analyzed geostatistically.
Date: November 29, 2001
Creator: Ruppel, Stephen C.; Jennings, James W. & Laubach, Stephen E.
Partner: UNT Libraries Government Documents Department


Description: As revealed by longitudinal bar resonance experiments, materials such as rocks and concrete show a rich diversity of nonlinear elastic behavior. As a function of increasing drive level, resonance frequencies shift downward by several percent, the resonant line shape changes, and harmonics and slow dynamics appear. Slow dynamics [1] refers to the time-dependent recovery of an elastic modulus to its initial value after being softened by large strain. In order to explore the mechanisms of nonlinear response including slow dynamics, we performed experiments on concrete and several different earth materials. The softening (conditioning) and recovery processes appear to be asymmetric. Conditioning takes place quickly; full recovery of the elastic modulus (as measured by drift of the resonance peak) takes minutes to hours, depending on the length of time the conditioning strain was applied. We find that for a wide variety of rocks and concretes, the recovery of the resonant frequency goes as log(time). Logarithmic time-dependence is a phenomenon associated with static friction and restoration of surface contacts, which in rocks probably takes place at touching crack surfaces.
Date: September 1, 1999
Creator: CATE, J. TEN & AL, ET
Partner: UNT Libraries Government Documents Department