Interpretation of dipole - dipole resistivity monitoring data at Cerro Prieto
Repetitive dipole - dipole resistivity data have been taken on a yearly basis by LBL at Cerro Prieto since 1978. Stations along a single profile line extending from the Cucapa Mountains to the center of the Mexicali Valley and passing over the present production zone have been remeasured with sufficient accuracy to detect subsurface changes in resistivity, some of which are probably related to fluid production. The precision of the most recent measurements (November, 1981) averages about 1%. Results from 2.5 years of monitoring indicate a 5% annual increase in apparent resistivity over the present production area and decreases in apparent resistivity of the same magnitude in the regions immediately eastward and westward from the production zone. The increase in resistivity in the production zone is most likely due to dilution of reservoir fluids with fresher water, as evidenced by a drop in chloride content of produced waters. An attempt was made to determine whether specific lithologic zones in wellbores show resistivity changes with time by comparing well logs from newly drilled wells with logs from older nearby wells. Results show that lateral resistivity variations within stratigraphic units between closely-spaced wells are sufficient to obscure possible temporal changes. The area of decreasing resistivity in the eastern part of the field is associated with a steeply dipping conductive body, a zone of higher thermal gradients and an increase in shale thickness in the section.
- Research Organization:
- Earth Sciences, Lawrence Berkeley Lab., Univ. of California, Berkeley, CA
- OSTI ID:
- 6240028
- Journal Information:
- Geothermics; (United States), Vol. 13:1
- Country of Publication:
- United States
- Language:
- English
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Long-term dipole-dipole resistivity monitoring at the Cerro Prieto geothermal field
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Related Subjects
CERRO PRIETO GEOTHERMAL FIELD
HYDROLOGY
RESISTIVITY SURVEYS
WATER INFLUX
DIPOLE MOMENTS
ELECTRIC CONDUCTIVITY
GEOTHERMAL FLUIDS
GEOTHERMAL GRADIENTS
GEOTHERMAL WELLS
RESISTIVITY LOGGING
ELECTRIC LOGGING
ELECTRICAL PROPERTIES
ELECTRICAL SURVEYS
FLUIDS
GEOPHYSICAL SURVEYS
GEOTHERMAL FIELDS
PHYSICAL PROPERTIES
SURVEYS
TEMPERATURE GRADIENTS
WELL LOGGING
WELLS
150301* - Geothermal Exploration & Exploration Technology- Geophysical Techniques & Surveys