Modeling and field studies of radon-222 in geothermal reservoirs
Radon-222 was shown to be useful in-situ tracer for studying thermodynamic, geologic, and transport properties of geothermal reservoirs. The relationships to reservoir properties are based on steady-state and non-steady-state models which incorporate the thermodynamic state and relative mobility of the fluids, and partitioning between the fluid phases. The steady-state thermodynamic models assume equilibrium between radon emanation from the reservoir rock and the geofluid concentration. The non-steady-state model solves the partial differential equations describing radon transport under transient two-phase geothermal flow conditions. Radon concentrations of fluids from nine geothermal reservoirs showed strong correlations to the specific volume of the reservoir fluid. Lowest values were associated with all-liquid wells at Cerro Prieto, Wairakei, and Los Azufres reservoirs, and the highest values for steady-producing wells at Serrazzano, Geysers, and Matsukawa reservoirs. Greater variability in radon concentration compared to fluid specific volume and individual reservoir correlations were attributed to geologic differences affecting radon volumetric emanation of the formations. Laboratory emanation studies on reservoir cores indicate porosity variations cause these changes in volumetric emanation. Sensitivity analysis indicates the usefulness of the model in designing future reservoir experiments.
- Research Organization:
- Stanford Univ., CA (USA)
- OSTI ID:
- 6684592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
150301* -- Geothermal Exploration & Exploration Technology-- Geophysical Techniques & Surveys
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510300 -- Environment
Terrestrial-- Radioactive Materials Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ALPHA DECAY RADIOISOTOPES
CERRO PRIETO GEOTHERMAL FIELD
DAYS LIVING RADIOISOTOPES
ENTHALPY
EVEN-EVEN NUCLEI
GEOLOGIC SURVEYS
GEOPHYSICAL SURVEYS
GEOTHERMAL FIELDS
GEOTHERMAL WELLS
GEYSERS GEOTHERMAL FIELD
HEAVY NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
MATSUKAWA GEOTHERMAL FIELD
NUCLEI
PHYSICAL PROPERTIES
RADIOISOTOPES
RADON 222
RADON ISOTOPES
SURVEYS
TEMPERATURE SURVEYS
THERMODYNAMIC PROPERTIES
TRACER TECHNIQUES
WAIRAKEI GEOTHERMAL FIELD
WELLS