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Title: Chemical and isotopic characteristics of the coso east flankhydrothermal fluids: implications for the location and nature of the heatsource

Abstract

Fluids have been sampled from 9 wells and 2 fumaroles fromthe East Flank of the Coso hydrothermal system with a view toidentifying, if possible, the location and characteristics of the heatsource inflows into this portion of the geothermal field. Preliminaryresults show that there has been extensive vapor loss in the system, mostprobably in response to production. Wells 38A-9, 51-16 and 83A-16 showthe highest CO2-CO-CH4-H2 chemical equilibration temperatures, rangingbetween 300-340oC, and apart from 38A-9, the values are generally inaccordance with the measured temperatures in the wells. Calculatedtemperatures for the fractionation of 13C between CO2 and CH4 are inexcess of 400oC in fluids from wells 38A-9, 64-16-RD2 and 51A-16,obviously pointing to equilibrium conditions from deeper portions of thereservoir. Given that the predominant reservoir rock lithologies in theCoso system are relatively silicic (granitic to dioritic), the isotopicsignatures appear to reflect convective circulation and equilibrationwithin rocks close to the plastic-brittle transition. 3He/4He signatures,in conjunction with relative volatile abundances in the Coso fluids,point to a possibly altered mantle source for the heat sourcefluids.

Authors:
; ; ; ;
Publication Date:
Research Org.:
COLLABORATION - GNS Science, National IsotopeCentre; Geothermal Program Office,Naval Air Weapons Station; and CosoOperating Company
OSTI Identifier:
903381
Report Number(s):
LBNL-62359
TRN: US200720%%311
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Conference
Resource Relation:
Conference: Thirty-second Workshop on Geothermal ReservoirEngineering, Stanford, CA, 22-24 January 2007
Country of Publication:
United States
Language:
English
Subject:
54; FRACTIONATION; FUMAROLES; GEOTHERMAL FIELDS; HEAT SOURCES; HYDROTHERMAL SYSTEMS; PRODUCTION; RESERVOIR ENGINEERING; RESERVOIR ROCK

Citation Formats

Christenson, B.W., Kennedy, B.M., Adams, M.C., Bjornstad, S.C., and Buck, C. Chemical and isotopic characteristics of the coso east flankhydrothermal fluids: implications for the location and nature of the heatsource. United States: N. p., 2007. Web.
Christenson, B.W., Kennedy, B.M., Adams, M.C., Bjornstad, S.C., & Buck, C. Chemical and isotopic characteristics of the coso east flankhydrothermal fluids: implications for the location and nature of the heatsource. United States.
Christenson, B.W., Kennedy, B.M., Adams, M.C., Bjornstad, S.C., and Buck, C. Mon . "Chemical and isotopic characteristics of the coso east flankhydrothermal fluids: implications for the location and nature of the heatsource". United States. doi:. https://www.osti.gov/servlets/purl/903381.
@article{osti_903381,
title = {Chemical and isotopic characteristics of the coso east flankhydrothermal fluids: implications for the location and nature of the heatsource},
author = {Christenson, B.W. and Kennedy, B.M. and Adams, M.C. and Bjornstad, S.C. and Buck, C.},
abstractNote = {Fluids have been sampled from 9 wells and 2 fumaroles fromthe East Flank of the Coso hydrothermal system with a view toidentifying, if possible, the location and characteristics of the heatsource inflows into this portion of the geothermal field. Preliminaryresults show that there has been extensive vapor loss in the system, mostprobably in response to production. Wells 38A-9, 51-16 and 83A-16 showthe highest CO2-CO-CH4-H2 chemical equilibration temperatures, rangingbetween 300-340oC, and apart from 38A-9, the values are generally inaccordance with the measured temperatures in the wells. Calculatedtemperatures for the fractionation of 13C between CO2 and CH4 are inexcess of 400oC in fluids from wells 38A-9, 64-16-RD2 and 51A-16,obviously pointing to equilibrium conditions from deeper portions of thereservoir. Given that the predominant reservoir rock lithologies in theCoso system are relatively silicic (granitic to dioritic), the isotopicsignatures appear to reflect convective circulation and equilibrationwithin rocks close to the plastic-brittle transition. 3He/4He signatures,in conjunction with relative volatile abundances in the Coso fluids,point to a possibly altered mantle source for the heat sourcefluids.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 08 00:00:00 EST 2007},
month = {Mon Jan 08 00:00:00 EST 2007}
}

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