Temperatures, heat flow, and water chemistry from drill holes in the Raft River geothermal system, Cassia County, Idaho
The Raft River area of Idaho contains a geothermal system of intermediate temperatures (approx. = 150/sup 0/C) at depths of about 1.5 km. Outside of the geothermal area, temperature measurements in three intermediate-depth drill holes (200 to 400 m) and one deep well (1500 m) indicate that the regional conductive heat flow is about 2.5 ..mu..cal/cm/sup 2/ sec or slightly higher and that temperature gradients range from 50/sup 0/ to 60/sup 0/C/km in the sediments, tuffs, and volcanic debris that fill the valley. Within and close to the geothermal system, temperature gradients in intermediate-depth drill holes (100 to 350 m) range from 120/sup 0/ to more than 600/sup 0/C/km, the latter value found close to an artesian hot well that was once a hot spring. Temperatures measured in three deep wells (1 to 2 km) within the geothermal area indicate that two wells are in or near an active upflow zone, whereas one well shows a temperature reversal. Assuming that the upflow is fault controlled, the flow is estimated to be 6 liter/sec per kilometer of fault length. From shut-in pressure data and the estimated flow, the permeability times thickness of the fault is calculated to be 2.4 darcy m. Chemical analyses of water samples from old flowing wells, recently completed intermediate-depth drill holes, and deep wells show a confused pattern. Geothermometer temperatures of shallow samples suggest significant re-equilibration at temperatures below those found in the deep wells. Silica geothermometer temperatures of water samples from the deep wells are in reasonable agreement with measured temperatures, whereas Na-K-Ca temperatures are significantly higher than measured temperatures. The chemical characteristics of the water, as indicated by chloride concentration, are extremely variable in shallow and deep samples. Chloride concentrations of the deep samples range from 580 to 2200 mg/kg.
- Research Organization:
- Geological Survey, Washington, DC (USA)
- OSTI ID:
- 5294453
- Report Number(s):
- USGS-OFR-80-2001; ON: DE82904217
- Resource Relation:
- Other Information: Portions of document are illegible
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HYDROTHERMAL SYSTEMS
WATER CHEMISTRY
RAFT RIVER VALLEY
HEAT FLOW
WELL TEMPERATURE
BOREHOLES
CALCIUM
GEOCHEMISTRY
GEOTHERMAL WELLS
GEOTHERMOMETRY
POTASSIUM
SILICA
SODIUM
TEMPERATURE GRADIENTS
ALKALI METALS
ALKALINE EARTH METALS
CAVITIES
CHALCOGENIDES
CHEMISTRY
ELEMENTS
ENERGY SYSTEMS
FEDERAL REGION X
GEOTHERMAL SYSTEMS
IDAHO
METALS
MINERALS
NORTH AMERICA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
RESERVOIR TEMPERATURE
SILICON COMPOUNDS
SILICON OXIDES
USA
WELLS
Geothermal Legacy
150301* - Geothermal Exploration & Exploration Technology- Geophysical Techniques & Surveys
150302 - Geothermal Exploration & Exploration Technology- Geochemical Techniques & Surveys