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Introduction to the proceedings of the Fourth Geothermal Reservoir Engineering Workshop, Stanford Geothermal Program

Description: The program committee for the Fourth Geothermal Workshop, presented in mid-December, 1978, decided that the format of the last two geothermal workshops should be continued; that is, the objective should be documented talks on field phenomena and reports on important results of research directly applicable to geothermal energy development. An arranged panel discussion of problems of common importance was also built into the program. Finally, it was decided to publish all submitted papers in the proceedings, but to select papers for presentation at the workshop program.
Date: January 1, 1978
Creator: Kruger, Paul & Ramey, Henry J., Jr.
Partner: UNT Libraries Government Documents Department

Slug Test Data Analysis in Reservoirs with Double Porosity Behaviour

Description: Pressure analysis for a slug test which corresponds to the flow period of a Drill Stem test is extended to wells in reservoirs with double-porosity behaviour. Solutions are obtained for either pseudo-steady state or transient interporosity flow. The distinctive specific features of both solutions are identified. Results presented are applicable to both naturally-fractured and layered reservoirs with the more permeable layer connecting to the wellbore. Type curves based on the pseudo-steady or transient interporosity flow are presented. These type curves are similar to the existing homogenous single layer type curve with addition of interporosity flow lines indicating double-porosity behaviour.
Date: December 15, 1983
Creator: Mateen, Khalid & Ramey, Henry J. Jr.
Partner: UNT Libraries Government Documents Department

Introduction to the Proceedings of the Sixth Geothermal Reservoir Engineering Workshop, Stanford Geothermal Program

Description: 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 thenumerical 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 i n 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 objectives of the Workshop, the bringing together of researchers, engineers and managers involved in geothermal reservoir study and development and the provision of a forum for the prompt and open ...
Date: December 18, 1980
Creator: Ramey, Henry J. Jr.; Kruger, Paul & Donaldson, Ian G.
Partner: UNT Libraries Government Documents Department

Well-test analysis for a well in a finite, circular reservoir

Description: This study presents drawdown and buildup pressure derivative type-curves for a well producing at a constant rate from the center of a finite, circular reservoir. Early time response (wellbore storage and skin effects) is correlated by C{sub D}e{sup 2s}, and late time response (outer boundary effects) by r{sup 2}{sub eD}/C{sub D}. The outer boundary may be closed, or at a constant pressure. Design relations are developed for the time to the beginning and the end of infinite-acting radial flow. Producing time effects on buildup responses are also discussed.
Date: January 1, 1988
Creator: Ambastha, Anil K. & Ramey, Henry J., Jr.
Partner: UNT Libraries Government Documents Department

The Significance of Early Time Data in Interference Testing for Linear Boundary Dectection

Description: This paper considers the significance of early time data for detecting linear boundaries using interference testing. When the ratio r{sub 2}/r{sub 1} is greater than 5, existing methods of analysis may be used. For ratios of r{sub 2}/r{sub 1} smaller than 5, special considerations are needed. When the ratio of r{sub 2}/r{sub 1} is smaller than 2, there is no significant indication of the presence of a linear boundary in the pressure response. The effects of missing pressure data during the early time flow period, and earth tides on the linear boundary analysis are described and demonstrated with a flow test in the Ohaaki geothermal field in New Zealand.
Date: January 21, 1986
Creator: Sageev, Abraham; Leaver, Jonathan D. & Ramey, Henry J. Jr.
Partner: UNT Libraries Government Documents Department

Experimental study of water adsorption on Geysers reservoir rocks

Description: Experimental isotherms of water vapor adsorption/desorption on three geothermal reservoir rock samples have been measured at temperatures of 80, 100, 120 and 140°C. Initial surface status of the sample was found to influence the amount of water adsorbed. At low relative pressures, adsorption is the dominant process of water retention onto the rock samples. Adsorption/desorption hysteresis was observed to exist over the whole pressure range at all temperatures. Similar observations were made for all three samples. The results of this study suggest that adsorption is important in storing water in geothermal reservoir rocks not only in itself, but also in inducing capillary condensation.
Date: January 28, 1993
Creator: Shang, Shubo; Horne, Roland N. & Ramey, Henry J., Jr.
Partner: UNT Libraries Government Documents Department

One-dimensional steam flow in porous media under desorption

Description: Performance forecasting for a hypothetical field with Geysers greywacke rock is performed to demonstrate the importance of desorption effect, the actual adsorption isotherm was found to be well approximated by the Langmuir equation. Results obtained suggest that adsorption is the dominant mechanism for steam in geothermal reservoirs.
Date: January 1, 1991
Creator: Nghiem, Cuong Phu & Ramey, Henry J., Jr.
Partner: UNT Libraries Government Documents Department

Measurement of surface area and water adsorption capacity of The Geysers rocks

Description: The measurement of the quantity of adsorbed water on geothermal reservoir rocks allows a more realistic estimation of reserves for vapor-dominated geothermal reservoirs. This study measured adsorptioddesorption isotherms of water vapor on rock samples from Calpine Co.'s well MLM-3, both core fragments and well cuttings from Coldwater Creek steamfield and a number of well cuttings from well Prati State 12, Northwest Geysers steam field. Surface areas of these rock samples were measured using nitrogen adsorption at 77K. The results of these measurements suggest that surface area is a crucial factor in determining the amount of water adsorption. Analysis of the water adsorption data indicates that adsorption is the dominant phenomena in the matrix of the reservoir rock at relative pressures below 0.8. Depending on the structure of the rock, capillary condensation contributes considerably to the total water retention at relative pressure between 0.8 and 1.0. However, there is no clear distinction between adsorption and capillary condensation and it is difficult in the experiments to determine when complete saturation occurs. A significant result of these experiments was the demonstration that well cuttings show adsorption characteristics very much like those obtained from core fragments. This should allow further adsorption measurements to be made more extensively and at lower cost.
Date: January 20, 1994
Creator: Shang, Shubo; Horne, Roland N. & Ramey, Henry J. Jr.
Partner: UNT Libraries Government Documents Department