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SVARTSENGI FIELD PRODUCTION DATA AND DEPLETION ANALYSIS

Description: There have been two major high-temperature geothermal field developments in Iceland in the last decade; Krafla in the north-east, and Svartsengi in the south-west. These and other geothermal developments have recently been reported by Palmason et al. The Krafla field will not be discussed here, but details about the field are available in Stefansson and the power plant in Eliasson et al. Several reservoir engineering studies of the Krafla field have been published. The Svartsengi field is one of several fields on the Reykjanes Peninsula in south-west Iceland. About 15 km west of Svartsengi, on the tip of the Peninsula, the Reykjanes field is now under development, primarily for seawater chemicals production. The recently drilled Eldvorp field is located in line between these two fields, about 5 km west of Svartsengi. There are also several fields to the east of Svartsengi, at 15-20 km distance. The Svartsengi, Eldvorp, and Reykjanes fields exist in the same tectonic-volcanic environment, and are surrounded by similar geohydrological conditions, as discussed by Georgsson; see also Gudmundsson et al. and Franzson. Optimum development of these and other fields on the Reykjanes Peninsula, requires an understanding of their depletion behavior with time; that is, how the reservoir pressure falls with production. While recognizing that no two geothermal fields are alike, we also realize that an understanding of the depletion behavior of Svartsengi, for example, may prove useful in the development of other similar and nearby fields. The main purpose of this paper is to report our depletion analysis of the Svartsengi field using lumped-parameter and water influx modeling: we also report the field's production history.
Date: January 22, 1985
Creator: Gudmundsson, J.S. & Thorhallsson, O.S.
Partner: UNT Libraries Government Documents Department

Pressure Profiles in Two-Phase Geothermal Wells: Comparison of Field Data and Model Calculations

Description: Increased confidence in the predictive power of two-phase correlations is a vital part of wellbore deliverability and deposition studies for geothermal wells. Previously, the Orkiszewski (1967) set of correlations has been recommended by many investigators to analyze geothermal wellbore performance. In this study, we use measured flowing pressure profile data from ten geothermal wells around the world, covering a wide range of flowrate, fluid enthalpy, wellhead pressure and well depth. We compare measured and calculated pressure profiles using the Orkiszewski (1967) correlations.
Date: January 21, 1986
Creator: Ambastha, A.K. & Gudmundsson, J.S.
Partner: UNT Libraries Government Documents Department

Deliverability and its Effect on Geothermal Power Costs

Description: The deliverability of liquid-dominated geothermal reservoirs is presented in terms of reservoir performance, and wellbore performance. Water influx modeling is used to match the performance of Wairakei in New Zealand, arid Ahuachapan in El Salvador. The inflow performance is given in terms of a linear productivity index for liquid-only flow, and a solution-gas drive relationship for two-phase flow. A 9-5/8'' production well is assumed, flowing 250 C water from 900 m depth, with a wellhead pressure of 100 psia. A Geothermal Development Model, that couples reservoir deliverability and power plant performance, and assigns costs to both, is used to illustrate how the development cost of geothermal electric power projects can be estimated.
Date: January 21, 1986
Creator: Gudmundsson, J. S. & Marcou, J. A.
Partner: UNT Libraries Government Documents Department

Geothermal Two-Phase Wellbore Flow: Pressure Drop Correlations and Flow Pattern Transitions

Description: In this paper we present some basic concepts of two-phase flow and review the Orkiszewski (1967) correlations which have been suggested by various investigators to perform well for geothermal wellbore flow situations. We also present a flow regime map based on the transition criteria used by Orkiszewski (1967) and show that most geothermal wells flow under slug flow regime. We have rearranged bubble- to slug-flow transition criterion used by Orkiszewski (1967) to show that the transition depends on the dimensionless pipe diameter number in addition to dimensionless liquid and gas velocity numbers. Our aim is also to identify what research may lead to improvements in two-phase pressure drop calculations for geothermal wellbore flow.
Date: January 21, 1986
Creator: Ambastha, A. K. & Gudmundsson, J. S.
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

Ninth workshop on geothermal reservoir engineering: Proceedings

Description: The attendance at the Workshop was similar to last year's with 123 registered participants of which 22 represented 8 foreign countries. A record number of technical papers (about 60) were submitted for presentation at the Workshop. The Program Committee, therefore, decided to have several parallel sessions to accommodate most of the papers. This format proved unpopular and will not be repeated. Many of the participants felt that the Workshop lost some of its unique qualities by having parallel sessions. The Workshop has always been held near the middle of December during examination week at Stanford. This timing was reviewed in an open discussion at the Workshop. The Program Committee subsequently decided to move the Workshop to January. The Tenth Workshop will be held on January 22-24, 1985. The theme of the Workshop this year was ''field developments worldwide''. The Program Committee addressed this theme by encouraging participants to submit field development papers, and by inviting several international authorities to give presentations at the Workshop. Field developments in at least twelve countries were reported: China, El Salvador, France, Greece, Iceland, Italy, Japan, Kenya, Mexico, New Zealand, the Philippines, and the United States. There were 58 technical presentations at the Workshop, of which 4 were not made available for publication. Several authors submitted papers not presented at the Workshop. However, these are included in the 60 papers of these Proceedings. The introductory address was given by Ron Toms of the U.S. Department of Energy, and the banquet speaker was A1 Cooper of Chevron Resources Company. An important contribution was made to the Workshop by the chairmen of the technical sessions. Other than Stanford Geothermal Program faculty members, they included: Don White (Field Developments), Bill D'Olier (Hydrothermal Systems), Herman Dykstra (Well Testing), Karsten Pruess (Well Testing), John Counsil (Reservoir Chemistry), Malcolm Mossman (Reservoir ...
Date: December 15, 1983
Creator: Ramey, H. J., Jr.; Kruger, P.; Miller, F.G.; Horne, R.N.; Brigham, W.E. & Gudmundsson, J.S. (Stanford Geothermal Program)
Partner: UNT Libraries Government Documents Department