| Title | Chemistry and Thermometry of Geothermal Water from Mountain Home Test Well MH-2B S: Preliminary Results |
|---|---|
| Authors | Lachmar, Thomas E.; Freeman, Thomas G.; Wood, Thomas R.; Shervais, John W.; Nielson, Dennis L. |
| Year | 2012 |
| Conference | Geothermal Resources Council Transactions |
| Keywords | Mountain Home; Snake River Plain; basalt; geothermal water; chemistry; hotspot |
| Abstract | A geothermal test well at Mountain Home AFB in southwestern Idaho encountered artesian flow of geothermal water from a depth of 1,745 m. Samples taken from the well head after 12 hours of flow had a pH of 9.59, and an electrical conductivity of 870 ?S. The high pH suggests that the water is at equilibrium with weathered basalt at the measured temperature. The water is high in sulfate relative to chloride and bicarbonate, and high in sodium relative to calcium and magnesium, but has a TDS content of only 1,120 mg/L. Pyrite is probably the source of the sulfate. Deuterium and oxygen-18 levels are -88 and -3.2 per mil, respectively, suggesting that the water is old, not meteoric, and/ or has undergone significant fractionation. Calculated equilibrium temperatures vary from ~134ºC to ~154ºC. The calculated temperatures are similar to those measured in the test well. The data suggest a potential electric-grade resource. Further work is in progress. |