Mineral Scaling in Geothermal Fields: a Review

Abstract

Geothermal power is an established energy source in several countries, for example New Zealand and Iceland. However the proposed geothermal operations in South Australia occurs at a much greater depth (5 km) and the heat source is radioactive decay rather than volcanism. A number of issues relating to the geochemistry of geothermal fluids are required to be considered and explored to ensure safe, economic energy production from geothermal fields. Low pH and saline waters, at temperatures much greater than 200oC, are highly corrosive, and it is vital to prevent the generation of scales as the brines are transported to the surface. This paper provides a review on silica, calcite and metal sulphide scaling at various geothermal fields. The solubility of silica and calcite as a function of temperature and/or pressure were discussed and how it affects scaling at various locations in the geothermal plant.