The Impact of Exploitation in the Surface Manifestations at Karaha Bodas Geothermal Field, Indonesia

Abstract

The Karaha Bodas Geothermal Field, operated by PT. Pertamina Geothermal Energy, is located in the Tasikmalaya and Garut regions of West Java, Indonesia. The geothermal power plant, with a capacity of 30 MWe, began commercial operations in April 2018. In 2023, geochemical monitoring of the surface manifestations identified four distinct complexes: Karaha, Cipanas-Pamoyanan, Talaga Bodas, and Pancur Tujuh. Each complex has a unique water chemistry: sulphate-type waters dominate in Karaha and Talaga Bodas, bicarbonate-type waters in Cipanas-Pamoyanan, and chloride-rich waters in Pancur Tujuh, where the high chloride levels are linked to magmatic fluids. Recent monitoring has shown rising temperatures and chloride levels in Pancur Tujuh, accompanied by a decrease in magnesium, indicating extensive reservoir boiling. This phenomenon is further supported by an increase in non-condensable gas (NCG) content in the fumaroles of Talaga Bodas. Additionally, extensive boiling has been observed in the production wells, attributed to the non-return of reinjected fluids. To address these challenges, an injection strategy is currently being tested in the Karaha Bodas field to improve reservoir management.