Interpretation of geothermal fluid compositions from Mendeleev volcano, Kunashir, Russia

Abstract

In this report, chemical analyses from the geothermal fields of the Mendeleev volcano (Kunashir Island), Krafla (Iceland) and Olkaria (Kenya) have been used to compare aquifer temperatures in wells using selected chemical geothermometers. Calcite and amorphous silica scaling potential has been assessed for selected wells and the environmental impact evaluated of the steam heated acid-sulphate waters on the rivers in the area. The speciation program WATCH was used to calculate amorphous silica and calcite saturation for variably boiled well waters for the assessment of scaling potential. The chemical data from the steam heated waters and wells were compared with requirements of Russian and European water quality standards. The geochemistry of the thermal water from Mendeleev volcano shows that the application of geothermometers to predict subsurface temperatures has to take into account physio-chemical parameters. Available data indicate that subsurface temperatures may be as high as 300°C. The physical processes that need to be taken into account include boiling, mixing with cold water, and steam heating. These processes affect water-mineral equilibria and can result in unreliable temperature predictions.