8 Matching Results

Search Results

Advanced search parameters have been applied.

Effects of Temperature and Saturation on the Velocity and Attenuation of Seismic Waves in Rocks: Applications to Geothermal Reservoir Evaluation

Description: In the evaluation of a geothermal resource it is critical to know the reservoir geometry, temperature, saturation, state of saturants, pore pressure, porosity and permeability. These are the parameters which will determine the production feasibility and cost effectivness of a geothermal prospect. The increasing sophistication of seismic wave data collection and processing and recent exerimental work on factors governing wave propagation in rocks has stimulated increased interest in the use of active seismic techniques to determine the in situ physical state of crustal rocks for engineering applications. In this paper we review experimental work showing how wave velocities in rocks are sensitive to parameters of interest to geothermal exploration; effective pressure, the degree of water saturation of the pores, and the bulk modulus of the pore phase. Seismic attenuation is even more sensitive to the degree of saturation and the microgeometry of the pores. Both velocity and attenuation are strongly temperature dependent and reflect thermal fracturing of the rocks at elevated temperatures. By combining data on attenuation and velocity of compressional and shear waves considerably greater constraints may be placed on the environmental state of the rocks than on the basis of P velocities alone.
Date: December 18, 1980
Creator: Jones, Terry; Murphy, William & Nur, Amos
Partner: UNT Libraries Government Documents Department

Determination of TDS in Geothermal Systems by Well-Log Analysis

Description: An estimate of t h e chemistry of the fluid within a geothermal reservoir is required to establish the geological source and the possible environmental impact of the fluid as well as scaling and corrosion problems which might develop during production. While a detailed analysis of the chemical composition of a geothermal fluid can only be obtained from a water sample, an estimate of the total dissolved solids (TDS) in equivalent sodium chloride (NaCl) concentration can be obtained from well logs. TDS can also be useful in geological correlation between wells. TDS can be determined directly from a pulsed neutron log and a porosity log, (if the type of formation is known), or from the water resistivity, R{sub w}, and the temperature, T. Three approaches are used to find R{sub w}, and thus TDS. The first method uses a dual induction focused log and information from the log heading. Next, is found by employing an electrical log and a porosity log. The last approach utilizes the spontaneous potential log and header data. Examples are provided to illustrate the techniques described which utilize calculated values of R{sub w} to determine TDS.
Date: December 16, 1980
Creator: Brown, Susan L.; Gobran, Brian D. & Sanyal, Subir K.
Partner: UNT Libraries Government Documents Department

Effect of Temperature and Solution Composition on the Permeability of St. Peters Sandstone: Role of Iron (III)

Description: The purpose of this study was to systematically investigate effects of temperature and fluid composition on the permeability of quartz sandstones. We have concentrated our initial efforts on the time and flow dependence at 2 elevated temperatures (100°C, 200°C).
Date: December 16, 1980
Creator: Potter, J.M.; Nur, A. & Dibble, W.E. Jr.
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

The Effect of Temperature on the Absolute Permeability to Distilled Water of Unconsolidated Sand Cores

Description: The work presented herein is a study of the effect of temperature on the absolute permeability to distilled water of unconsolidated sandstones at one confining pressure. The absolute permeability to distilled water of Ottawa silica sand was not dependent on the temperature level.
Date: December 16, 1980
Creator: Sageev, A.; Gobran, B.D.; Brigham, W.E. & Ramey, H.J. Jr.
Partner: UNT Libraries Government Documents Department

Geothermal Energy Extraction Modeling

Description: To gain some insight into the potential significance of the effects of thermal stressing on heat transfer characteristics, an exploratory study was conducted to observe the effects of thermal stressing on rock strength and porosity.
Date: December 18, 1980
Creator: Nelson, D.; Kruger, P. & Hunsbedt, A
Partner: UNT Libraries Government Documents Department

Sixth workshop on geothermal reservoir engineering: Proceedings

Description: INTRODUCTION TO THE PROCEEDINGS OF THE SIXTH GEOTHERMAL RESERVOIR ENGINEERING WORKSHOP, STANFORD GEOTHERMAL PROGRAM Henry J. Ramey, Jr., and Paul Kruger Co-Principal Investigators Ian G. Donaldson Program Manager Stanford Geothermal Program The Sixth Workshop on Geothermal Reservoir Engineering convened at Stanford University on December 16, 1980. As with previous Workshops the attendance was around 100 with a significant participation from countries other than the United States (18 attendees from 6 countries). In addition, there were a number of papers from foreign contributors not able to attend. Because of the success of all the earlier workshops there was only one format change, a new scheduling of Tuesday to Thursday rather than the earlier Wednesday through Friday. This change was in general considered for the better and will be retained for the Seventh Workshop. Papers were presented on two and a half of the three days, the panel session, this year on the numerical modeling intercomparison study sponsored by the Department of Energy, being held on the second afternoon. This panel discussion is described in a separate Stanford Geothermal Program Report (SGP-TR42). This year there was a shift in subject of the papers. There was a reduction in the number of papers offered on pressure transients and well testing and an introduction of several new subjects. After overviews by Bob Gray of the Department of Energy and Jack Howard of Lawrence Berkeley Laboratory, we had papers on field development, geopressured systems, production engineering, well testing, modeling, reservoir physics, reservoir chemistry, and risk analysis. A total of 51 papers were contributed and are printed in these Proceedings. It was, however, necessary to restrict the presentations and not all papers printed were presented. Although the content of the Workshop has changed over the years, the format to date has proved to be satisfactory. The ...
Date: December 18, 1980
Creator: Ramey, H. J., Jr. & Kruger, P.
Partner: UNT Libraries Government Documents Department