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The purpose of this research was to continue the assessment of the low-temperature geothermal resources of Cache Valley, Utah initiated by the Utah Geological and Mineral Survey under U.S. Department of Energy (DOE) contract DE-AS07-77ET 28393. Field work consisted of locating 90 wells and springs throughout the study area, collecting water samples for later laboratory analyses, and field measurement of pH, temperature, bicarbonate alkalinity, and electrical conductivity. Na+, K+, Ca+2, Mg+2, SiO2, Fe, SO4-2, C1-, F-, and total dissolved solids were determined in the laboratory. Temperature profiles were measured in 12 additional, unused wells. Thermal gradients calculated from the profiles were approximately the same as the average for the Basin and Range province, about 35 degrees C/km. One well produced a gradient of 297 degrees C/km, most were probably as a result of a near-surface occurrence of warm water. Possible warm water reservoir temperatures were calculated using both the silica an the Na-K-Ca geothermometers, with the results averaging about 50-100 degrees C. If mixing calculations were applied, taking into account the temperatures and silica contents of both warm springs or wells and the cold groundwater, reservoir temperatures up to about 200 degrees C were indicated. Considering measured surface water temperatures, calculated reservoir temperatures, thermal gradients, and the local geology, most of the Cache Valley, Utah area is unsuited for geothermal development. However, the areas of North Logan, Benson, and Trenton were found to have anomalously warm groundwater in comparison to the background temperature of 13.0 degrees C for the study area. The warm water has potential for isolated energy development but is not warm enough for major commercial development.


DOE/ET/28393--T1 Report of Investigation, Utah Geological and Mineral Survey, no. 174