Fluid Chemistry and Hydrology of the Herber Geothermal System, Calilfornia

Abstract

This paper presents the results of chemical and isotopic analyses of geothermal fluids and microthermomet-ric measurements on fluid inclusions from the Heber geothermal system. The chemical analyses indicate that the reservoir fluids have salinities near 15000 ppm total dissolved solids and low gas contents. Small but consis-tent differences in the concentrations of total C02, 8, L i, 0-18, and d e u t - e r i u m are found between the fluid s that feed the two power plants. These difference s may be due to d i v e r g e n t paths of the thermal fluids as they flow from the south. Fl u i d in c l u s i on homogenization temperatures are similar to the present temperature s in a gradient well near the zone of upflow but are generally lower in the other two wells studied. Salinities determined from the freezing measurements suggest t h at the fluids contained within the in - c l u s ions are mixtures of the product i o n fluid s and other lower - salinity waters.