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Title: Hydrothermal model of the Momotombo geothermal system, Nicaragua

The Momotombo geothermal field is situated on the northern shore of Lake Managua at the foot of the active Momotombo volcano. The field has been producing electricity since 1983 and has an installed capacity of 70 MWe. The results of geological, geochemical and geophysical studies have been reported in various internal reports. The isotopic studies were funded by the International Atomic Energy Agency (IAEA), Vienna to develop a hydrothermal model of the geothermal system. The chemical and stable isotopic data ({delta}{sup 18}O and {delta}D) of the geothermal fluid suggest that the seasonal variation in the production characteristics of the wells is related to the rapid infiltration of local precipitation into the reservoir. The annual average composition of Na{sup +}, K{sup +} and Mg{sup 2+} plotted on the Na-K-Mg triangular diagram presented by Giggenbach (1988) to identify the state of rock-water interaction in geothermal reservoirs, shows that the fluids of almost every well are shifting towards chemically immature water due to reservoir exploitation. This effect is prominent in wells Mt-2, Mt-12, Mt-22 and Mt-27. The local groundwaters including surface water from Lake Managua have much lower tritium concentrations than some of the geothermal well fluids, which have about 6 T.U. Themore » high-tritium wells are located along a fault inferred from a thermal anomaly. The tritium concentration is also higher in fluids from wells close to the lake. This could indicate that older local precipitation waters are stored in a deep layer within the lake and that they are infiltrating into the geothermal reservoir.« less
Authors:
 [1] ; ; ;  [2]
  1. Instituto de Investigaciones Electricas, Morelos (Mexico)
  2. Empresa Nicaragueense de Energia de Electricidad, Managua (Nicaragua) [and others
Publication Date:
OSTI Identifier:
472054
Report Number(s):
CONF-960124-
CNN: Project Nic/8/008; TRN: 96:005767-0005
Resource Type:
Conference
Resource Relation:
Conference: 21. Stanford workshop on geothermal reservoir engineering, Stanford, CA (United States), 22-24 Jan 1996; Other Information: PBD: 1996; Related Information: Is Part Of Proceedings of the twenty-first workshop on geothermal reservoir engineering; PB: 595 p.
Publisher:
Stanford Univ., Stanford, CA (United States)
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; MOMOTOMBO GEOTHERMAL FIELD; GEOCHEMISTRY; HISTORICAL ASPECTS; NICARAGUA; GEOTHERMAL RESOURCES; HYDROTHERMAL SYSTEMS; GEOLOGIC MODELS; RESERVOIR ROCK; ROCK-FLUID INTERACTIONS