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Title: The Preston Geothermal Resources; Renewed Interest in a Known Geothermal Resource Area

The Preston Geothermal prospect is located in northern Cache Valley approximately 8 kilometers north of the city of Preston, in southeast Idaho. The Cache Valley is a structural graben of the northern portion of the Basin and Range Province, just south of the border with the Eastern Snake River Plain (ESRP). This is a known geothermal resource area (KGRA) that was evaluated in the 1970's by the State of Idaho Department of Water Resources (IDWR) and by exploratory wells drilled by Sunedco Energy Development. The resource is poorly defined but current interpretations suggest that it is associated with the Cache Valley structural graben. Thermal waters moving upward along steeply dipping northwest trending basin and range faults emanate in numerous hot springs in the area. Springs reach temperatures as hot as 84° C. Traditional geothermometry models estimated reservoir temperatures of approximately 125° C in the 1970’s study. In January of 2014, interest was renewed in the areas when a water well drilled to 79 m (260 ft) yielded a bottom hole temperature of 104° C (217° F). The well was sampled in June of 2014 to investigate the chemical composition of the water for modeling geothermometry reservoir temperature. Traditional magnesium correctedmore » Na-K-Ca geothermometry estimates this new well to be tapping water from a thermal reservoir of 227° C (440° F). Even without the application of improved predictive methods, the results indicate much higher temperatures present at much shallower depths than previously thought. This new data provides strong support for further investigation and sampling of wells and springs in the Northern Cache Valley, proposed for the summer of 2015. The results of the water will be analyzed utilizing a new multicomponent equilibrium geothermometry (MEG) tool called Reservoir Temperature Estimate (RTEst) to obtain an improved estimate of the reservoir temperature. The new data suggest that other KGRAs and overlooked areas may need to be investigated using improved geothermal exploration methods.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [3] ;  [3]
  1. Univ. of Idaho, Idaho Falls, ID (United States)
  2. Idaho National Lab. (INL), Idaho Falls, ID (United States)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Earth Sciences Div.
Publication Date:
OSTI Identifier:
1178068
Report Number(s):
INL/CON--14-33368
TRN: US1500158
DOE Contract Number:
AC07-05ID14517
Resource Type:
Conference
Resource Relation:
Conference: 40. Workshop on Geothermal Reservoir Engineering, Stanford, CA (United States), 26-28 Jan 2015
Research Org:
Idaho National Laboratory (INL), Idaho Falls, ID (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Geothermal Technologies Office (EE-4G)
Country of Publication:
United States
Language:
English
Subject:
15 GEOTHERMAL ENERGY; HOT SPRINGS; IDAHO; GEOTHERMAL RESOURCES; KGRA; RESERVOIR TEMPERATURE; GEOTHERMOMETRY; TEMPERATURE RANGE 0400-1000 K; GEOTHERMAL EXPLORATION; GEOTHERMAL FLUIDS; DEPTH; CHEMICAL COMPOSITION; EQUILIBRIUM geothermal, Cache Valley, geochemistry, RTEst, sou