Hot Dry Rock Geothermal Exploration in Australia

Abstract

Hot dry rock (HDR) geothermal energy is obtained by circulating water between injection and production wells through hot subsurface rocks. The recovered hot water should be around 250°C for efficient electricity generation. South Australia has become a focus for HDR developments due to its exceptionally hot subsurface rocks. Previous HDR projects have focused on areas of known high geothermal gradient, based, for example, on experience from petroleum wells, e.g. the European Soultz-sous-Forêts site and Geodynamics? Habanero-1 well in the Cooper Basin. An alternative strategy is to explore for the highest geothermal gradients closest to electricity markets. Petratherm Ltd. holds geothermal exploration licences within the uniquely hot South Australian Heat Flow Anomaly and will target buried thermally anomalous granites and radiogenic iron oxides therein. Thermal modelling indicates that temperatures of 250°C may be attained at depths <4 km within the licences. The thermal conductivity of the cover rocks is as important a factor as the heat-generating potential of the basement in generating exceptionally high geothermal gradients.