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Modeling of geochemical interactions between acidic and neutral fluids in the Onikobe Geothermal Reservoir

Description: Two types of fluids are encountered in the Onikobe geothermal reservoir, one is neutral and the other is acidic (pH=3). It is hypothesized that acidic fluid might be upwelling along a fault zone and that an impermeable barrier might be present between the acidic and neutral fluid zones. We carried out reactive geothermal transport simulations using TOUGHREACT (Xu and Pruess, 1998 and 2001) to test such a conceptual model. One-dimensional models were used to study the geochemical behavior due to mixing of the two fluids. Mn-rich smectite precipitated near the mixing front and is likely to form an impermeable barrier between regions with acidic and neutral fluids.
Date: January 10, 2003
Creator: Todaka, Norifumi; Akasaka, Chitoshi; Xu, Tianfu & Pruess, Karsten
Partner: UNT Libraries Government Documents Department

Increasing Waterflood Reserves in the Wilmington Oil Field Through Improved Reservoir Characterization and Reservoir Management

Description: The objectives of this quarterly report are to summarize the work conducted under each task during the reporting period October - December 1997 and to report all technical data and findings as specified in the "Federal Assistance Reporting Checklist". 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 cased-hole logging tools. 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 translate measurements 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 lateral recompletions as well as other recompletion techniques such as the sand consolidation through steam injection.
Date: January 26, 1998
Creator: Phillips, Chris; Moos, Dan; Clarke, Don; Nguyen, John; Tagbor, Kwasi; Koerner, Roy et al.
Partner: UNT Libraries Government Documents Department

Breakthrough Time for the Source-Sink Well Doublet

Description: A pressure transient analysis method is presented for interpreting breakthrough time between two constant rate wells. The wells are modeled as two line source wells in an infinite reservoir. The first well injects at a constant rate and the second well produces at a constant rate. We studied the effects of transient pressure conditions on breakthrough time. The first arrival of injected fluid at the production well may be significantly longer under transient condition than under steady state condition. A correlation of the deviation of the breakthrough time for transient pressure conditions from the steady state condition is presented.
Date: January 21, 1986
Creator: Menninger, Will & Sageev, Abraham
Partner: UNT Libraries Government Documents Department

Laboratory measurement of sorption in porous media

Description: A new apparatus for measuring steam adsorption-desorption isothermally on rock samples has been installed and initial runs made for rock samples from geothermal reservoirs. The amounts adsorbed measured in these experiments are the same order of magnitude as previous experiments.
Date: January 1, 1992
Creator: Harr, M.S.; Pettit, P. & Ramey, J.J., Jr.
Partner: UNT Libraries Government Documents Department

Interdisciplinary study of reservoir compartments and heterogeneity. Quarterly technical progress report, July 1995--September 1995

Description: 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.
Date: October 27, 1995
Creator: Kirk, C.W. Van & Thompson, R.S.
Partner: UNT Libraries Government Documents Department

Crosshole EM for oil field characterization and EOR monitoring: Field examples from Lost Hills, California

Description: A steamflood recently initiated by Mobil Development and Production U.S. at the Lost Hills No 3 oil field in California is notable for its shallow depth and the application of electromagnetic (EM) geophysical techniques to monitor the subsurface steam flow. Steam was injected into three stacked eastward-dipping unconsolidated oil sands at depths from 60 to 120 m; the plume is expected to develop as an ellipsoid aligned with the regional northwest-southeast strike. Because of the shallow depth of the sands and the high viscosity of the heavy oil, it is important to track the steam in the unconsolidated sediments for both economic and safety reasons. Crosshole and surface-to-borehole electromagnetic imaging were applied for reservoir characterization and steamflood monitoring. The crosshole EM data were collected to map the interwell distribution of the high-resistivity oil sands and to track the injected steam and hot water. Measurements were made in two fiberglass-cased observation wells straddling the steam injector on a northeast-southwest profile. Field data were collected before the steam drive, to map the distribution of the oil sands, and then 6 and 10 months after steam was injected, to monitor the expansion of the steam chest. Resistivity images derived from the collected data clearly delineated the distribution and dipping structure of the target oil sands. Difference images from data collected before and during steamflooding indicate that the steam chest has developed only in the middle and lower oil sands, and it has preferentially migrated westward in the middle oil sand and eastward in the deeper sand. Surface-to-borehole field data sets at Lost Hills were responsive to the large-scale subsurface structure but insufficiently sensitive to model steam chest development in the middle and lower oil sands. As the steam chest develops further, these data will be of more use for process monitoring.
Date: July 16, 1996
Creator: Wilt, M.; Schenkel, C.; Wratcher, M.; Lambert, I.; Torres-Verdin, C. & H.W., Tseng
Partner: UNT Libraries Government Documents Department

Integration of advanced geoscience and engineering techniques to quantify interwell heterogeneity. Quarterly technical report, April 1--June 30, 1995

Description: Objective is to integrate advanced geoscience and reservoir engineering concepts to quantify the dynamics of fluid-rock and fluid-fluid interactions as related to reservoir architecture and lithologic characterization. During this period, studies were made of the permeability, wettability, and porosity of the Sulimar Queen Formation.
Date: September 1, 1995
Creator: Martin, F.D.; Buckley, J.S.; Weiss, W.W. & Ouenes, A.
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

Research on oil recovery mechanisms in heavy oil reservoirs. Progress report, July 1, 1995--September 30, 1995

Description: The goal of this research is to conduct studies towards the enhanced recovery of heavy petroleum. Five areas are being studied: flow properties; in-situ combustion; steam with additives; formation evaluation; and field support services. Progress is described.
Date: December 1, 1995
Creator: Brigham, W.E.
Partner: UNT Libraries Government Documents Department

Research program on fractured petroleum reservoirs. Second quarterly, April 1--June 30, 1995

Description: Very large compositional variation both areally and vertically has been observed in some hydrocarbon reservoirs. Several mechanisms are believed to contribute to such variations: gravitational segregation, molecular diffusion, thermal diffusion, and thermal convection. At isothermal conditions only gravitational segregation and molecular diffusion contribute to vertical compositional grading. The Gibbs segregation concept can properly account for this process. Under nonisothermal conditions, which is often the case, the process is thermodynamically irreversible and therefore Gibbs criteria of equilibrium cannot be invoked. The current literature often combines the Gibbs segregation concept and the natural convection process to formulate the interaction of convection and gravity segregation for multicomponent systems at nonisothermal conditions. The Dary law is also used without the modification of the velocity weighing for multicomponent systems. Such a formulation may not describe the process properly. This report formulates compositional variation in hydrocarbon reservoirs at nonisothermal condition. Results for the special case of gravity and thermal diffusion are also presented.
Date: July 31, 1995
Creator: Firoozabadi, A.
Partner: UNT Libraries Government Documents Department

Reservoir characterization by cross-hole seismic imaging. Final report, September 15, 1989--June 30, 1994

Description: Better characterization of reservoirs requires better images of those reservoirs. This report documents the research undertaken at the Massachusetts Institute of Technology`s Earth Resources Laboratory (ERL) to improve seismic tomographic images. In addition, the new imaging method was applied to a data set collected in a producing oil field. The method developed is nonlinear travel time tomography. This technique uses the travel time of the first arriving energy at a receiver and distributes that time back along realistic ray paths. This is an important distinction between this method and previous methods that used either straight ray paths from source to receiver or fixed ray paths (ray paths fixed by an a priori model). The nonlinearity arises during each iteration in the matching of observed travel times with those determined from a model. In this technique the model is updated during each iteration (the velocity structure is changed) and new ray paths are computed in that update model. Thus the resulting image is based on physically realistic ray paths. Tomography resolution is not merely a simple function of the wavelength of the seismic energy used but also involves a measure of how well a given region has been sampled by ray paths. Moreover, the ray paths must represent a wide variation in inclination as they pass through a given spatial cell. This imaging technique was applied to a compressional wave data set collected at ERL`s Michigan Test Site located in the Northern Reef Trend of MI. It consists of two deep boreholes that straddle a producing reef. Two hundred source positions and two hundred receiver positions were used to obtain 40,000 ray paths. Although ERL`s boreholes are 2,000 ft apart, kilohertz data was obtained. The resulting image of the reservoir showed a low velocity zone inside the reef and a thin ...
Date: July 1, 1995
Creator: Turpening, R.M.; Matarese, J.R. & Toksoez, M.N.
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

A 3-D hydrodynamic dispersion model for modeling tracer transport in Geothermal Reservoirs

Description: A 3-D hydrodynamic dispersion model for tracer transport is developed and implemented into the TOUGH2 EOS3 (T2R3D) module. The model formulation incorporates a full dispersion tensor, based on a 3-D velocity field with a 3-D, irregular grid in a heterogeneous geological system. Two different weighting schemes are proposed for spatial average of 3-D velocity fields and concentration gradients to evaluate the mass flux by dispersion and diffusion of a tracer or a radionuclide. This new module of the TOUGH2 code is designed to simulate processes of tracer/radionuclide transport using an irregular, 3-D integral finite difference grid in non-isothermal, three-dimensional, multiphase, porous/fractured subsurface systems. The numerical method for this transport module is based on the integral finite difference scheme, as in the TOUGH2 code. The major assumptions of the tracer transport module are: (a) a tracer or a radionuclide is present and transported only within the liquid phase, (b) transport mechanisms include molecular diffusion and hydrodynamic dispersion in the liquid phase in addition to advection, and (c) first order decay and linear adsorption on rock grains are taken into account. The tracer or radionuclide is introduced as an additional mass component into the standard TOUGH2 formulation, time is discretized fully implicitly, and non-linearities of the conservation equations are handled using the Newton/Raphson iteration. We have verified this transport module by comparison with results of a 2-D transport problem for which an analytical solution is available. In addition, a field application is described to demonstrate the use of the proposed model.
Date: January 26, 1998
Creator: Wu, Yu-Shu & Pruess, Karsten
Partner: UNT Libraries Government Documents Department

Strategies for gas production from hydrate accumulations under various geologic conditions

Description: In this paper we classify hydrate deposits in three classes according to their geologic and reservoir conditions, and discuss the corresponding production strategies. Simple depressurization appears promising in Class 1 hydrates, but its appeal decreases in Class 2 and Class 3 hydrates. The most promising production strategy in Class 2 hydrates involves combinations of depressurization and thermal stimulation, and is clearly enhanced by multi-well production-injection systems. The effectiveness of simple depressurization in Class 3 hydrates is limited, and thermal stimulation (alone or in combination with depressurization) through single well systems seems to be the strategy of choice in such deposits.
Date: April 29, 2003
Creator: Moridis, G. & Collett, T.
Partner: UNT Libraries Government Documents Department

Three dimensional interpretations of single-well electromagnetic data for geothermal applications

Description: An efficient 3-D electromagnetic (EM) inversion algorithm has been developed for geothermal applications and tested successfully using a set of single-hole EM logging data. The data was collected at an oil field undergoing CO{sub 2} injection in southern California using a single-hole EM tool, Geo-BILT, developed by Electromagnetic Instruments, Inc (EMI). The tool is equipped with a multi-component source, and multi-component receivers at different separations. The inversion result provides a reasonable electrical conductivity image to a distance of 10 m from the well, and illustrates several zones with lateral conductivity variations that could not be resolved with traditional induction logging tools. The successful case study demonstrates potential applications of the tool and software for characterizing fracture systems in geothermal reservoirs.
Date: January 9, 2004
Creator: Tseng, Hung-Wen & Lee, Ki Ha
Partner: UNT Libraries Government Documents Department

Advanced Reservoir Characterization in the Antelope Shale to Establish the Viability of C02 Enhanced Oil Recovery in California's Monterey Formation Siliceous Shales

Description: The primary objective of this research is to conduct advanced reservoir characterization and modeling studies in the Antelope Shale reservoir. Characterization studies will be used to determine the technical feasibility of implementing a CO2 enhanced oil recovery project in the Antelope Shale in Buena Vista Hills Field. The Buena Vista Hills pilot CO2 project will demonstrate the economic viability and widespread applicability of CO2 flooding in fractured siliceous shale reservoirs of the San Joaquin Valley. The research consists of four primary work processes: Reservoir Matrix and Fluid Characterization; Fracture Characterization; Reservoir Modeling and Simulation; and CO2 Pilot Flood and Evaluation. Work done in these areas is subdivided into two phases or budget periods. The first phase of the project will focus on the application of a variety of advanced reservoir characterization techniques to determine the production characteristics of the Antelope Shale reservoir. Reservoir models based on the results of the characterization work will be used to evaluate how the reservoir will respond to secondary recovery and EOR processes. The second phase of the project will include the implementation and evaluation of an advanced enhanced oil recovery (EOR) pilot in the West Dome of the Buena Vista Hills Field.
Date: April 25, 1997
Creator: Morea, Michael F.
Partner: UNT Libraries Government Documents Department

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

Description: 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.
Date: August 28, 2000
Creator: Durlofsky, Louis J.
Partner: UNT Libraries Government Documents Department

Time Scaling of the Rates of Produced Fluids in Laboratory Displacements

Description: In this report, the use of an asymptotic method, based on the time scaling of the ratio of produced fluids, to infer the relative permeability exponent of the displaced phase near its residual saturation, for immiscible displacements in laboratory cores was proposed. Sufficiently large injection rates, the existence of a power law can be detected, and its exponent inferred, by plotting in an appropriate plot the ratio of the flow rates of the two fluids at the effluent for some time after breakthrough.
Date: February 27, 2001
Creator: Laroche, Catherine; Chen, Min; Yortsos, Yanis C. & Kamath, Jairam
Partner: UNT Libraries Government Documents Department