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Title: Geothermal Field Case Studies that Document the Usefulness of Models in Predicting Reservoir and Well Behavior

Abstract

The geothermal industry has shown significant interest in case histories that document field production histories and demonstrate the techniques which work best in the characterization and evaluation of geothermal systems. In response to this interest, LBL has devoted a significant part of its geothermal program to the compilation and analysis of data from US and foreign fields (e.g., East Mesa, The Geysers, Susanville, and Long Valley in California; Klamath Fall in Oregon; Valles Caldera, New Mexico; Cerro Prieto and Los Azufres in Mexico; Krafla and Nesjavellir in Iceland; Larderello in Italy; Olkaria in Kenya). In each of these case studies we have been able to test and validate in the field, or against field data, the methodology and instrumentation developed under the Reservoir Technology Task of the DOE Geothermal Program, and to add to the understanding of the characteristics and processes occurring in geothermal reservoirs. Case study results of the producing Cerro Prieto and Olkaria geothermal fields are discussed in this paper. These examples were chosen because they illustrate the value of conceptual and numerical models to predict changes in reservoir conditions, reservoir processes, and well performance that accompany field exploitation, as well as to reduce the costs associated withmore » the development and exploitation of geothermal resources.« less

Authors:
Publication Date:
Research Org.:
Earth Sciences Division, LBNL (Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA)
Sponsoring Org.:
USDOE
OSTI Identifier:
890486
Report Number(s):
CONF-890352-7
TRN: US200622%%639
Resource Type:
Conference
Resource Relation:
Conference: DOE Research and Development for the Geothermal Marketplace, Proceedings of the Geothermal Program Review VII; San Francisco, CA, March 21-23, 1989
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; EVALUATION; GEOTHERMAL FIELDS; GEOTHERMAL INDUSTRY; GEOTHERMAL RESOURCES; GEOTHERMAL SYSTEMS; KLAMATH FALLS; LAWRENCE BERKELEY LABORATORY; LONG VALLEY; PERFORMANCE; PRODUCTION; Geothermal Legacy

Citation Formats

Lippmann, Marcelo J. Geothermal Field Case Studies that Document the Usefulness of Models in Predicting Reservoir and Well Behavior. United States: N. p., 1989. Web.
Lippmann, Marcelo J. Geothermal Field Case Studies that Document the Usefulness of Models in Predicting Reservoir and Well Behavior. United States.
Lippmann, Marcelo J. Tue . "Geothermal Field Case Studies that Document the Usefulness of Models in Predicting Reservoir and Well Behavior". United States. doi:. https://www.osti.gov/servlets/purl/890486.
@article{osti_890486,
title = {Geothermal Field Case Studies that Document the Usefulness of Models in Predicting Reservoir and Well Behavior},
author = {Lippmann, Marcelo J.},
abstractNote = {The geothermal industry has shown significant interest in case histories that document field production histories and demonstrate the techniques which work best in the characterization and evaluation of geothermal systems. In response to this interest, LBL has devoted a significant part of its geothermal program to the compilation and analysis of data from US and foreign fields (e.g., East Mesa, The Geysers, Susanville, and Long Valley in California; Klamath Fall in Oregon; Valles Caldera, New Mexico; Cerro Prieto and Los Azufres in Mexico; Krafla and Nesjavellir in Iceland; Larderello in Italy; Olkaria in Kenya). In each of these case studies we have been able to test and validate in the field, or against field data, the methodology and instrumentation developed under the Reservoir Technology Task of the DOE Geothermal Program, and to add to the understanding of the characteristics and processes occurring in geothermal reservoirs. Case study results of the producing Cerro Prieto and Olkaria geothermal fields are discussed in this paper. These examples were chosen because they illustrate the value of conceptual and numerical models to predict changes in reservoir conditions, reservoir processes, and well performance that accompany field exploitation, as well as to reduce the costs associated with the development and exploitation of geothermal resources.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Mar 21 00:00:00 EST 1989},
month = {Tue Mar 21 00:00:00 EST 1989}
}

Conference:
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  • The geothermal industry has shown significant interest in case histories that document field production histories and demonstrate the techniques which work best in the characterization and evaluation of geothermal systems. In response to this interest, LBL has devoted a significant art of its geothermal program to the compilation and analysis of data from US and foreign fields (e.g., East Mesa, The Geysers, Susanville, and Long Valley in California; Klamath Falls in Oregon; Valles Caldera, New Mexico; Cerro Prieto and Los Azufres in Mexico; Krafla and Nesjavellir in Iceland; Larderello in Italy; Olkaria in Kenya). In each of these case studiesmore » we have been able to test and validate in the field, or against field data, the methodology and instrumentation developed under the Reservoir Technology Task of the DOE Geothermal Program, and to add to the understanding of the characteristics and processes occurring in geothermal reservoirs. Case study results of the producing Cerro Prieto and Olkaria geothermal fields are discussed in this paper. These examples were chosen because they illustrate the value of conceptual and numerical models to predict changes in reservoir conditions, reservoir processes, and well performance that accompany field exploitation, as well as to reduce the costs associated with the development and exploitation of geothermal resources. 14 refs., 6 figs.« less
  • Gas chemistry from 28 wells complement water chemistry and physical data in developing a reservoir model for the Bacon-Manito geothermal project (BMGP), Philippines. Reservoir temperature, T HSH, and steam fraction, y, are calculated or extrapolated from the grid defined by the Fischer-Tropsch (FT) and H 2-H 2S (HSH) gas equilibria reactions. A correction is made for H 2 that is lost due to preferential partitioning into the vapor phase and the reequilibration of H 2S after steam loss.
  • A hydrogeologic model of the Cerro Prieto geothermal field in its undisturbed state, developed on the basis of well log and reservoir engineering data, is discussed. According to this model, geothermal fluid enters the field from the east through a deep (>10,000 ft) sandstone aquifer which is overlain by a thick shale unit which locally prevents the upward migration of the fluid. As it flows westward, the fluid gradually rises through faults and sandy gaps in the shale unit. Eventually, some of the fluid leaks to the surface in the western part of the field, while the rest mixes withmore » surrounding colder waters.« less
  • Tracer and geochemistry measurements in fractured Hot Dry Rock (HDR) geothermal reservoirs are usually performed after a fracture connection has been established and constant, nearly equal inlet and outlet flow rates have been achieved. however, during hydraulic fracturing experiments designed to create a low-impedance fracture connection between two wells, the inlet and outlet flow rates can be dramatically different and can vary during the test, forcing us to revise the common analytical methods for interpreting tracer response curves and geochemistry behavior. This study presents tracer and geochemistry data from several hydraulic fracturing experiments at the Fenton Hill, NM, HDR geothermalmore » reservoir. Tracers have been injected at various times during these tests: (1) initially, before any flow communication existing between the wells; (2) shortly after a flow connection was established; and (3) after the outlet flow had increased to its steady state value. An idealized flow model consisting of a combination of main fracture flow paths and fluid leakoff into secondary permeability explains the different tracer response curves for these cases, and allows us to predict the fracture volume of the main paths. The geochemistry during these experiments supports our previously developed models postulating the existence of a high concentration indigenous ''pore fluid''. Also, the quartz and Na-K-Ca geothermometers have been used successfully to identify the temperatures and depths at which fluid traveled while in the reservoir. The quartz geothermometer is somewhat more reliable because at these high temperatures (about 250 C) the injected fluid can come to equilibrium with quartz in the reservoir. The Na-K-Ca geothermometer relies on obtaining a sample of the indigenous pore fluid, and thus is somewhat susceptible to problems of dilution with the injection fluid.« less
  • This study presents tracer and geochemistry data from several hydraulic fracturing experiments at the Fenton Hill, NM, HDR geothermal reservoir. Tracers have been injected at various times during these tests: (1) initially, before any flow communication existed between the wells; (2) shortly after a flow connection was established; and (3) after the outlet flow had increased to its steady state value. An idealized flow model consisting of a combination of main fracture flow paths and fluid leakoff into secondary permeability explains the different tracer response curves for these cases, and allows us to predict the fracture volume of the mainmore » paths. The geochemistry during these experiments supports our previously developed models postulating the existence of a high concentration indigenous ''pore fluid.'' Also, the quartz and Na-K-Ca geothermometers have been used successfully to identify the temperatures and depths at which fluid traveled while in the reservoir. The quartz geothermometer is somewhat more reliable because at these high temperatures (about 250/sup 0/C) the injected fluid can come to equilibrium with quartz in the reservoir. The Na-K-Ca geothermometer relies on obtaining a sample of the indigenous pore fluid, and thus is somewhat susceptible to problems of dilution with the injection fluid. 14 refs., 6 figs., 1 tab.« less