| Abstract |
Under a co-operative agreement with the U.S. Department of Energy (DOE), Utah State University is carrying out a research program to identify promising geothermal prospects in the Snake River Plain (SRP) volcanic province. The goals of this Phase 1 study are to: (1) adapt the methodology of Play Fairway Analysis for geothermal exploration, creating a formal basis for its application to geothermal systems, (2) assemble relevant data for the Snake River Plain volcanic province from publicly available and private sources, and (3) build a geothermal play fairway model for the Snake River Plain that will allow the delineation of the most promising plays. A promising play type is associated with the SRP basaltic sill-complexes characterized by fault-controlled permeability, volcanic sill heat source, and lake sediment seal. The area around Mountain Home Air Force base in western Snake River Plain hosts a geothermal system of the latter type. The Mountain Home area is characterized by high heat flow and temperature gradient. Temperature data are available from 18 boreholes with depths equal to or greater than 200 m. Although there are large variations, the average temperature gradient exceeds 80oC/km. This paper presents a preliminary 3-D numerical model of the natural-state (i.e. pre-production state) of the Mountain Home geothermal area. The model volume is 34,320 cubic kilometers (110 km in the east-west direction, 80 km in the north-south direction, and 3.9 km in the vertical direction). Available temperature profiles from the five deep wells with depths ranging from ~1340 m to ~3390 m (MH-1, MH-2, Bostic1, Lawrence D No.1, and Anschutz No. 1) are used to constrain the 3-D numerical model. The preliminary natural state model will be further developed during Phase 2 as additional geological, geophysical, and well data become available. |