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Title: Field-based tests of geochemical modeling codes using New Zealand hydrothermal systems

Abstract

Hydrothermal systems in the Taupo Volcanic Zone, North Island, New Zealand are being used as field-based modeling exercises for the EQ3/6 geochemical modeling code package. Comparisons of the observed state and evolution of the hydrothermal systems with predictions of fluid-solid equilibria made using geochemical modeling codes will determine how the codes can be used to predict the chemical and mineralogical response of the environment to nuclear waste emplacement. Field-based exercises allow us to test the models on time scales unattainable in the laboratory. Preliminary predictions of mineral assemblages in equilibrium with fluids sampled from wells in the Wairakei and Kawerau geothermal field suggest that affinity-temperature diagrams must be used in conjunction with EQ6 to minimize the effect of uncertainties in thermodynamic and kinetic data on code predictions.

Authors:
; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab., CA (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
60846
Report Number(s):
UCRL-ID-118009
ON: DE95005658; TRN: 95:004303
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Jun 1994
Country of Publication:
United States
Language:
English
Subject:
05 NUCLEAR FUELS; 15 GEOTHERMAL ENERGY; 58 GEOSCIENCES; 99 MATHEMATICS, COMPUTERS, INFORMATION SCIENCE, MANAGEMENT, LAW, MISCELLANEOUS; HYDROTHERMAL SYSTEMS; THERMODYNAMICS; ROCK-FLUID INTERACTIONS; HIGH-LEVEL RADIOACTIVE WASTES; UNDERGROUND DISPOSAL; GEOCHEMISTRY; GEOLOGIC MODELS; COMPARATIVE EVALUATIONS; KAWERAU GEOTHERMAL FIELD; NEW ZEALAND; WAIRAKEI GEOTHERMAL FIELD; Yucca Mountain Project; Geothermal Legacy

Citation Formats

Bruton, C.J., Glassley, W.E., and Bourcier, W.L.. Field-based tests of geochemical modeling codes using New Zealand hydrothermal systems. United States: N. p., 1994. Web. doi:10.2172/60846.
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Bruton, C.J., Glassley, W.E., & Bourcier, W.L.. Field-based tests of geochemical modeling codes using New Zealand hydrothermal systems. United States. doi:10.2172/60846.
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Bruton, C.J., Glassley, W.E., and Bourcier, W.L.. Wed . "Field-based tests of geochemical modeling codes using New Zealand hydrothermal systems". United States. doi:10.2172/60846. https://www.osti.gov/servlets/purl/60846.
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@article{osti_60846,
title = {Field-based tests of geochemical modeling codes using New Zealand hydrothermal systems},
author = {Bruton, C.J. and Glassley, W.E. and Bourcier, W.L.},
abstractNote = {Hydrothermal systems in the Taupo Volcanic Zone, North Island, New Zealand are being used as field-based modeling exercises for the EQ3/6 geochemical modeling code package. Comparisons of the observed state and evolution of the hydrothermal systems with predictions of fluid-solid equilibria made using geochemical modeling codes will determine how the codes can be used to predict the chemical and mineralogical response of the environment to nuclear waste emplacement. Field-based exercises allow us to test the models on time scales unattainable in the laboratory. Preliminary predictions of mineral assemblages in equilibrium with fluids sampled from wells in the Wairakei and Kawerau geothermal field suggest that affinity-temperature diagrams must be used in conjunction with EQ6 to minimize the effect of uncertainties in thermodynamic and kinetic data on code predictions.},
doi = {10.2172/60846},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Jun 01 00:00:00 EDT 1994},
month = {Wed Jun 01 00:00:00 EDT 1994}
}
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Technical Report:
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DOI:  10.2172/60846
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  • ; ;
    Hydrothermal systems in the Taupo Volcanic Zone, North Island, New Zealand are being used as field-based modeling exercises for the EQ3/6 geochemical modeling code package. Comparisons of the observed state and evolution of the hydrothermal systems with predictions of fluid-solid equilibria made using geochemical modeling codes will determine how the codes can be used to predict the chemical and mineralogical response of the environment to nuclear waste emplacement. Field-based exercises allow us to test the models on time scales unattainable in the laboratory. Preliminary predictions of mineral assemblages in equilibrium with fluids sampled from wells in the Wairakei and Kaweraumore » geothermal field suggest that affinity-temperature diagrams must be used in conjunction with EQ6 to minimize the effect of uncertainties in thermodynamic and kinetic data on code predictions.« less

  • ; ;
    Hydrothermal systems in the Taupo Volcanic Zone, North Island, New Zealand are being used as field-based modeling exercises for the EQ3/6 geochemical modeling code package. Comparisons of the observed state and evolution of the hydrothermal systems with predictions of fluid-solid equilibria made using geochemical modeling codes will determine how the codes can be used to predict the chemical and mineralogical response of the environment to nuclear waste emplacement. Field-based exercises allow us to test the models on time scales unattainable in the laboratory. Preliminary predictions of mineral assemblages in equilibrium with fluids sampled from wells in the Wairakei and Kaweraumore » geothermal field suggest that affinity-temperature diagrams must be used in conjunction with EQ6 to minimize the effect of uncertainties in thermodynamic and kinetic data on code predictions.« less

  • ; ;
    Hydrothermal systems in the Taupo Volcanic Zone, North Island, New Zealand are being used as field-based modeling exercises for the EQ3/6 geochemical modeling code package. Comparisons of the observed state and evolution of selected portions of the hydrothermal systems with predictions of fluid-solid equilibria made using geochemical modeling codes will: (1) ensure that we are providing adequately for all significant processes occurring in natural systems; (2) determine the adequacy of the mathematical descriptions of the processes; (3) check the adequacy and completeness of thermodynamic data as a function of temperature for solids, aqueous species and gases; and (4) determine themore » sensitivity of model results to the manner in which the problem is conceptualized by the user and then translated into constraints in the code input. Preliminary predictions of mineral assemblages in equilibrium with fluids sampled from wells in the Wairakei geothermal field suggest that affinity-temperature diagrams must be used in conjunction with EQ6 to minimize the effect of uncertainties in thermodynamic and kinetic data on code predictions. The kinetics of silica precipitation in EQ6 will be tested using field data from silica-lined drain channels carrying hot water away from the Wairakei borefield.« less

  • ;
    Two hydrothermal sites on the North Island of New Zealand were selected to evaluate methods for conducting geochemical model validation in natural systems. At the Ngawha site, mixing of waters from different source regions has been well documented. Simulations achieved agreement with the natural system if certain constraints were used. At the Rotokawa site, where sulfur deposition occurs via oxidation of H{sub 2}S, several models were generated, two of which provide some agreement with the features of the natural system. The simulations provide detail sufficient to guide further field and laboratory tests. The results demonstrate that the diverse New Zealandmore » hydrothermal systems are an exceptional natural experiment that can allow through testing of computer models intended to simulate natural processes important for potential nuclear waste repositories.« less

  • An investigation of the deuterium variation in a limited number of samples from New Zealand hydrothermal areas was conducted. It was found that sufficient variations occur to show that measurement of O/sup 18/ and deuterium isotopes should yield results which would add to the knowledge of these hydrothermal systems. (J.R.D.)