27 Matching Results

Search Results

Advanced search parameters have been applied.

Analysis of Injection-Backflow Tracer Tests in Fractured Geothermal Reservoirs

Description: Tracer tests have been an important technique for determining the flow and reservoir characteristics in various rock matrix systems. While the interwell tracer tests are aimed at the characterization of the regions between the wells, single-well injection-backflow tracer tests may be useful tools of preliminary evaluation, before implementing long term interwell tracer tests. This work is concerned with the quantitative evaluation of the tracer return profiles obtained from single well injection-backflow tracer tests. First, two mathematical models of tracer transport through fractures, have been reviewed. These two models are based on two different principles: Taylor Dispersion along the fracture and simultaneous diffusion in and out of the adjacent matrix. Then the governing equations for the transport during the injection-backflow tests have been solved. Finally the results were applied to field data obtained from Raft River and East Mesa geothermal fields. In order to determine the values of the parameters of the models that define the transport mechanisms through fractures a non-linear optimization technique was employed. 26 refs., 10 figs.
Date: January 20, 1987
Creator: Kocabas, I. & Horne, R.N.
Partner: UNT Libraries Government Documents Department

Multivariate optimization of production systems: The time dimension

Description: Traditional analysis of oil and gas production systems treats individual nodes one at a time. This only calculates a feasible solution which is not necessarily optimal. Multivariate optimization is able to determine the most profitable configuration, including all variables simultaneously. The optimization can also find the optimal recovery over a period of time, rather than just at a single instant as in traditional methods. This report describes the development of multivariate optimization for situations in which the decision variables may change as a function of time. For example, instead of estimating a tubing size which is optimal over the life of the project, this approach determines a series of optimal tubing sizes which may change from year to year. Examples show that under an optimal strategy, tubing size can be changed only infrequently while still increasing profitability of a project. The methods used in this work considered the special requirements of objectives which are not smooth functions of their decision variables. The physical problems considered included artificial lift production systems.
Date: April 1, 1993
Creator: Ravindran, N. & Horne, R.N.
Partner: UNT Libraries Government Documents Department

Ultrasonic rate measurement of multiphase flow

Description: On of the most important tools in production logging and well testing is the downhole flowmeter. Unfortunately, existing tools are inaccurate outside of an idealized single phase flow, regime. Spinner tools are inaccurate at extremely high or low, flow rates and when the flow rate is variable. Radioactive tracer tools have similar inaccuracies and are extremely sensitive to the flow regime. Both tools completely fail in the presence of multiphase flow, whether gas/ oil, gas/water or fluid/solid. Downhole flowmetering is important for locating producing zones and thief zones and monitoring production and injection rates. The effects of stimulation can also be determined. This goal of this project is the investigation of accurate downhole flowmetering techniques for all single phase flow regimes and multiphase flows. The measurement method investigated in this report is the use of ultrasound. There are two ways to use ultrasound for fluid velocity measurement. The first method, examined in Chapter 2, is the contrapropagation, or transit-time, method which compares travel times with and against fluid flow. Chapter 3 details the second method which measures the Doppler frequency shift of a reflected sound wave in the moving fluid. Both of these technologies need to be incorporated in order to build a true multiphase flowmeter. Chapter 4 describes the proposed downhole multiphase flowmeter. It has many advantages besides the ones previously mentioned and is in full in that chapter.
Date: January 1, 1993
Creator: Dannert, D.A. & Horne, R.N.
Partner: UNT Libraries Government Documents Department

Multivariate optimization of production systems: The time dimension

Description: Traditional analysis of oil and gas production systems treats individual nodes one at a time. This only calculates a feasible solution which is not necessarily optimal. Multivariate optimization is able to determine the most profitable configuration, including all variables simultaneously. The optimization can also find the optimal recovery over a period of time, rather than just at a single instant as in traditional methods. This report describes the development of multivariate optimization for situations in which the decision variables may change as a function of time. For example, instead of estimating a tubing size which is optimal over the life of the project, this approach determines a series of optimal tubing sizes which may change from year to year. Examples show that under an optimal strategy, tubing size can be changed only infrequently while still increasing profitability of a project. The methods used in this work considered the special requirements of objectives which are not smooth functions of their decision variables. The physical problems considered included artificial lift production systems.
Date: April 1, 1993
Creator: Ravindran, N. & Horne, R. N.
Partner: UNT Libraries Government Documents Department

Geothermal reservoir engineering research at Stanford University. First annual report, October 1, 1980-September 30, 1981

Description: The work on energy extraction experiments concerns the efficiency with which the in-place heat and fluids can be produced. The work on noncondensable gas reservoir engineering covers both the completed and continuing work in these two interrelated research areas: radon emanation from the rock matrix of geothermal reservoirs, and radon and ammonia variations with time and space over geothermal reservoirs. Cooperative research programs with Italy and Mexico are described. The bench-scale experiments and well test analysis section covers both experimental and theoretical studies. The small core model continues to be used for the study of temperature effects on absolute permeability. The unconsolidated sand study was completed at the beginning of this contract period. The Appendices describe some of the Stanford Geothermal program activities that results in interactions with the geothermal community. These occur in the form of SGP Technical Reports, presentations at technical meetings and publications in the open literature.
Date: September 1, 1981
Creator: Brigham, W.E.; Horne, R.N.; Kruger, P.; Miller, F.G. & Ramey, H.J. Jr.
Partner: UNT Libraries Government Documents Department

Geothermal-reservoir engineering research at Stanford University. Second annual report, October 1, 1981-September 30, 1982

Description: Progress in the following tasks is discussed: heat extraction from hydrothermal reservoirs, noncondensable gas reservoir engineering, well test analysis and bench-scale experiments, DOE-ENEL Cooperative Research, Stanford-IIE Cooperative Research, and workshop and seminars. (MHR)
Date: September 1, 1982
Creator: Ramey, H.J. Jr.; Kruger, P.; Horne, R.N.; Brigham, W.E. & Miller, F.G.
Partner: UNT Libraries Government Documents Department

Reservoir technology - geothermal reservoir engineering research at Stanford. Fifth annual report, October 1, 1984-September 30, 1985

Description: The objective is to carry out research on geothermal reservoir engineering techniques useful to the geothermal industry. A parallel objective is the training of geothermal engineers and scientists. The research is focused toward accelerated development of hydrothermal resources through the evaluation of fluid reserves, and the forecasting of field behavior with time. Injection technology is a research area receiving special attention. The program is divided into reservoir definition research, modeling of heat extraction from fractured reservoirs, application and testing of new and proven reservoir engineering technology, and technology transfer. (ACR)
Date: September 1, 1985
Creator: Ramey, H.J. Jr.; Kruger, P.; Horne, R.N.; Miller, F.G. & Brigham, W.E.
Partner: UNT Libraries Government Documents Department

Geothermal reservoir engineering computer code comparison and validation using the GEONZ simulator program

Description: It was originally proposed to use the GEOTHERM geothermal simulator program to prepare solutions to the first five of the six Department of Energy computer code comparison sets. Valid solutions were anticipated in all of the five problems attempted, but it was expected that problems 3 and 4 might present some difficulties. A more recent version of the program, called GEONZ became available and was used successfully on problems 3 and 4. The new program, GEONZ, had additional capabilities that enabled it to handle both superheated steam and counterflows of steam and water. The choice of the GEONZ code is discussed, followed by an in-depth description of the solutions obtained for problems 1 through 5. The problem statements are included as Appendix A. The five problems are: 1-D Avdonin Solution, 1-D well test analysis, 2-D flow in fracture/block medium, 2-D phase system with drainage, and flow in a 2-D areal reservoir. (MHR)
Date: November 14, 1980
Creator: Horne, R.N.; Ogbe, D.O.; Temeng, K. & Ramey, H.J. Jr.
Partner: UNT Libraries Government Documents Department

Geothermal Reservoir Engineering Research. Fourth annual report, October 1, 1983-September 30, 1984

Description: Reservoir definition research consisted of well test analysis and bench-scale experiments. Well testing included both single-well pressure drawdown and buildup testing, and multiple-well interference testing. The development of new well testing methods continued to receive major emphasis during the year. Work included a project on multiphase compressibility, including the thermal content of the rock. Several projects on double-porosity systems were completed, and work was done on relative-permeability. Heat extraction from rock will determine the long-term response of geothermal reservoirs to development. The work in this task area involved a combination of physical and mathematical modeling of heat extraction from fractured geothermal reservoirs. International cooperative research dealt with adsorption of water on reservoir cores, the planning of tracer surveys, and an injection and tracer test in the Los Azufres fields. 32 refs.
Date: September 1, 1984
Creator: Ramey, H.J. Jr.; Kruger, P.; Horne, R.N.; Brigham, W.E. & Miller, F.G.
Partner: UNT Libraries Government Documents Department

Geothermal reservoir engineering research at Stanford University. Third annual report for the period October 1, 1982-September 30, 1983

Description: Progress is reported in the following areas: heat extraction from hydrothermal reservoirs; radon reservoir engineering; well test analysis and bench scale experiments; field applications; workshop, seminars, and technical information; reinjection technology; and seismic monitoring of vapor/liquid interfaces. (MHR)
Date: September 1, 1983
Creator: Ramey, H.J. Jr.; Kruger, P.; Horne, R.N.; Brigham, W.E. & Miller, F.G.
Partner: UNT Libraries Government Documents Department

Geothermal research and development program

Description: Progress is reported on the following projects: adsorption of water vapor on reservoir rocks, drawdown and buildup pressure analysis in multiwell reservoirs, adsorption parameters from experimental data, tritium tracer movement at the Geysers, adsorption modeling, and effects of earth tides on downhole pressures.
Date: October 8, 1992
Creator: Ramey, H.J. Jr.; Horne, R.N. & Miller, F.G.
Partner: UNT Libraries Government Documents Department

Reservoir and injection technology: Geothermal reservoir engineering research at Stanford: Third annual report for the period October 1, 1986 through September 30, 1987: (Final report)

Description: This paper discusses different aspects of geothermal reservoir engineering. General topics covered are: reinjection technology, reservoir technology, and heat extraction. (LSP)
Date: February 1, 1988
Creator: Ramey, H.J. Jr.; Horne, R.N.; Miller, F.G. & Brigham, W.E.
Partner: UNT Libraries Government Documents Department

Geothermal research and development program. Second annual technical report, July 1, 1991--June 30, 1992

Description: Progress is reported on the following projects: adsorption of water vapor on reservoir rocks, drawdown and buildup pressure analysis in multiwell reservoirs, adsorption parameters from experimental data, tritium tracer movement at the Geysers, adsorption modeling, and effects of earth tides on downhole pressures.
Date: October 8, 1992
Creator: Ramey, H. J. Jr.; Horne, R. N. & Miller, F. G.
Partner: UNT Libraries Government Documents Department

Ultrasonic rate measurement of multiphase flow

Description: On of the most important tools in production logging and well testing is the downhole flowmeter. Unfortunately, existing tools are inaccurate outside of an idealized single phase flow, regime. Spinner tools are inaccurate at extremely high or low, flow rates and when the flow rate is variable. Radioactive tracer tools have similar inaccuracies and are extremely sensitive to the flow regime. Both tools completely fail in the presence of multiphase flow, whether gas/ oil, gas/water or fluid/solid. Downhole flowmetering is important for locating producing zones and thief zones and monitoring production and injection rates. The effects of stimulation can also be determined. This goal of this project is the investigation of accurate downhole flowmetering techniques for all single phase flow regimes and multiphase flows. The measurement method investigated in this report is the use of ultrasound. There are two ways to use ultrasound for fluid velocity measurement. The first method, examined in Chapter 2, is the contrapropagation, or transit-time, method which compares travel times with and against fluid flow. Chapter 3 details the second method which measures the Doppler frequency shift of a reflected sound wave in the moving fluid. Both of these technologies need to be incorporated in order to build a true multiphase flowmeter. Chapter 4 describes the proposed downhole multiphase flowmeter. It has many advantages besides the ones previously mentioned and is in full in that chapter.
Date: January 1, 1993
Creator: Dannert, D. A. & Horne, R. N.
Partner: UNT Libraries Government Documents Department

The use of tracers to analyze the effects of reinjection into fractured geothermal reservoirs

Description: This paper discusses the use of tracers as a reservoir engineering tool in fractured geothermal reservoirs. The principle concern in injecting cooler spent fluids into a fractured reservoir is that the fluids may move through high permeability channels and return to the production wells after contacting a relatively small volume of rock. As a consequence of this rapid transport, the fluids will be only partially reheated and after a short period time will effectively mine the heat from the limited volume of rock. The production wells will then experience a rapid and premature reduction in thermal output. Tracers can be used to infer the existence of high mobility conduits between injection and production wells and to monitor chemical changes of an injected fluid. Since tracer arrival precedes thermal breakthrough, tracer tests are a very useful forecasting tool.
Date: January 1, 1987
Creator: Horne, R.N.; Johns, R.A.; Adams, M.C.; Moore, J.N. & Stiger, S.G.
Partner: UNT Libraries Government Documents Department

Well Test Analysis Research

Description: Well test analysis offers a rapid way to perform an initial assessment of geothermal systems. Well testing includes both pressure drawdown and buildup testing, and interference testing. Development of new well test analyses receives major emphasis in the Stanford Geothermal Program. During the year, quite a few studies were completed, and reports and papers presented on a variety of well test analysis methods. The paper summarizes some of the more important results.
Date: December 16, 1980
Creator: Ramey, H.J. Jr.; Horne, R.N.; Miller, F.G. & Brigham, W.E.
Partner: UNT Libraries Government Documents Department

Bench-Scale Experiments in the Stanford Geothermal Program

Description: The emphasis of the smaller scale laboratory of the Stanford Geothermal Program is on improving the understanding of the physics of flow through porous materials in a geothermal environment. Three major investigations are in progress: (1) examination of the phenomenon of vapor pressure lowering in porous media, (2) determination of the temperature dependence of absolute and relative permeabilities of steam and water in sandstones under high confining pressures, and (3) observation of steady and unsteady, single- and two-phase flows of water or brine through permeable cores. In addition, development continues on the dielectric constant liquid content detector—a device which would prove extremely useful in these and subsequent experiments. 10 refs., 4 figs.
Date: December 14, 1977
Creator: Horne, R.N.; Counsil, J.; Hsiech, C.H.; Ramey, H.J. Jr. & Kruger, P.
Partner: UNT Libraries Government Documents Department

Reservoir and injection technology and Heat Extraction Project

Description: For the Stanford Geothermal Program in the fiscal year 1989, the task areas include predictive modeling of reservoir behavior and tracer test interpretation and testing. Major emphasis is in reservoir technology, reinjection technology, and heat extraction. Predictive modeling of reservoir behavior consists of a multi-pronged approach to well test analysis under a variety of conditions. The efforts have been directed to designing and analyzing well tests in (1) naturally fractured reservoirs; (2) fractured wells; (3) complex reservoir geometries; and, (4) gas reservoirs including inertial and other effects. The analytical solutions for naturally fractured reservoirs are determined using fracture size distribution. In the study of fractured wells, an elliptical coordinate system is used to obtain semi-analytical solutions to finite conductivity fractures. Effort has also been directed to the modeling and creation of a user friendly computer program for steam/gas reservoirs including wellbore storage, skin and non-Darcy flow effects. This work has a complementary effort on modeling high flow rate wells including inertial effects in the wellbore and fractures. In addition, work on gravity drainage systems is being continued.
Date: December 31, 1989
Creator: Horne, R.N.; Ramey, H.H. Jr.; Miller, F.G.; Brigham, W.E. & Kruger, P.
Partner: UNT Libraries Government Documents Department

Reservoir and injection technology and Heat Extraction Project. Fifth annual report, January 1, 1989--December 31, 1989

Description: For the Stanford Geothermal Program in the fiscal year 1989, the task areas include predictive modeling of reservoir behavior and tracer test interpretation and testing. Major emphasis is in reservoir technology, reinjection technology, and heat extraction. Predictive modeling of reservoir behavior consists of a multi-pronged approach to well test analysis under a variety of conditions. The efforts have been directed to designing and analyzing well tests in (1) naturally fractured reservoirs; (2) fractured wells; (3) complex reservoir geometries; and, (4) gas reservoirs including inertial and other effects. The analytical solutions for naturally fractured reservoirs are determined using fracture size distribution. In the study of fractured wells, an elliptical coordinate system is used to obtain semi-analytical solutions to finite conductivity fractures. Effort has also been directed to the modeling and creation of a user friendly computer program for steam/gas reservoirs including wellbore storage, skin and non-Darcy flow effects. This work has a complementary effort on modeling high flow rate wells including inertial effects in the wellbore and fractures. In addition, work on gravity drainage systems is being continued.
Date: December 1, 1989
Creator: Horne, R. N.; Ramey, H. H. Jr.; Miller, F. G.; Brigham, W. E. & Kruger, P.
Partner: UNT Libraries Government Documents Department

Doublet Tracer Testing in Klamath Falls, Oregon

Description: A tracer test was carried out in a geothermal doublet system to study the injection behavior of a developed reservoir known to be fractured. The doublet produces about 320 gpm of 160 F water that is used for space heating and then injected; the wells are spaced 250 ft apart. Tracer breakthrough was observed in 2 hours and 45 minutes in the production well, indicating fracture flow. However, the tracer concentrations were low and indicated porous media flow; the tracers mixed with a reservoir volume much larger than a fracture.
Date: December 15, 1983
Creator: Gudmundsson, J.S.; Johnson, S.E.; Horne, R.N.; Jackson, P.B. & Culver, G.G.
Partner: UNT Libraries Government Documents Department

Fourteenth workshop geothermal reservoir engineering: Proceedings

Description: The Fourteenth Workshop on Geothermal Reservoir Engineering was held at Stanford University on January 24--26, 1989. Major areas of discussion include: (1) well testing; (2) various field results; (3) geoscience; (4) geochemistry; (5) reinjection; (6) hot dry rock; and (7) numerical modelling. For these workshop proceedings, individual papers are processed separately for the Energy Data Base.
Date: January 1, 1989
Creator: Ramey, H. J., Jr.; Kruger, P.; Horne, R. N.; Miller, F. G.; Brigham, W. E. & Cook, J. W.
Partner: UNT Libraries Government Documents Department

Fourteenth workshop geothermal reservoir engineering: Proceedings

Description: The Fourteenth Workshop on Geothermal Reservoir Engineering was held at Stanford University on January 24--26, 1989. Major areas of discussion include: (1) well testing; (2) various field results; (3) geoscience; (4) geochemistry; (5) reinjection; (6) hot dry rock; and (7) numerical modelling. For these workshop proceedings, individual papers are processed separately for the Energy Data Base.
Date: December 31, 1989
Creator: Ramey, H. J. Jr.; Kruger, P.; Horne, R. N.; Miller, F. G.; Brigham, W. E. & Cook, J. W.
Partner: UNT Libraries Government Documents Department

Thirteenth workshop on geothermal reservoir engineering: Proceedings

Description: PREFACE The Thirteenth Workshop on Geothermal Reservoir Engineering was held at Stanford University on January 19-21, 1988. Although 1987 continued to be difficult for the domestic geothermal industry, world-wide activities continued to expand. Two invited presentations on mature geothermal systems were a keynote of the meeting. Malcolm Grant presented a detailed review of Wairakei, New Zealand and highlighted plans for new development. G. Neri summarized experience on flow rate decline and well test analysis in Larderello, Italy. Attendance continued to be high with 128 registered participants. Eight foreign countries were represented: England, France, Iceland, Italy, New Zealand, Japan, Mexico and The Philippines. A discussion of future workshops produced a strong recommendation that the Stanford Workshop program continue for the future. There were forty-one technical presentations at the Workshop. All of these are published as papers in this Proceedings volume. Four technical papers not presented at the Workshop are also published. In addition to these forty five technical presentations or papers, the introductory address was given by Henry J. Ramey, Jr. from the Stanford Geothermal Program. The Workshop Banquet speaker was Gustavo Calderon from the Inter-American Development Bank. We thank him for sharing with the Workshop participants a description of the Bank???s operations in Costa Rica developing alternative energy resources, specifically Geothermal, to improve the country???s economic basis. His talk appears as a paper in the back of this volume. The chairmen of the technical sessions made an important contribution to the workshop. Other than Stanford faculty members they included: J. Combs, G. T. Cole, J. Counsil, A. Drenick, H. Dykstra, K. Goyal, P. Muffler, K. Pruess, and S. K. Sanyal. The Workshop was organized by the Stanford Geothermal Program faculty, staff and students. We would like to thank Marilyn King, Pat Oto, Terri Ramey, Bronwyn Jones, Yasmin Gulamani, and Rosalee ...
Date: January 21, 1988
Creator: Ramey, H.J. Jr.; Kruger, P.; Horne, R.N.; Brigham, W.E.; Miller, F.G. & Cook, J.W. (Stanford Geothermal Program)
Partner: UNT Libraries Government Documents Department