High Heat Flow and Geothermal Opportunities in the Sunda Basin, Indonesia: A Case for Sustainable Energy Development

Abstract

Indonesia's geothermal development has traditionally focused on Quaternary volcanic arcs, as exemplified by power plants in Sibayak (North Sumatra), Salak (West Java), Kamojang (West Java), and Sarulla (North Sumatra). However, increasing socio-environmental challenges in densely populated regions highlight the need to explore alternative geothermal provinces. This study evaluates the geothermal potential of the offshore Sunda Basin using data from 21 oil wells. The results reveal heat flow values of 60–140 mW/m², geothermal gradients of 30°–70°C/km, and thermal conductivity ranging from 1.66 to 2.14 W/m °C—indicating favourable thermal conditions within sedimentary units. These characteristics are structurally supported by a thin crust (~30 km), normal faulting, and back-arc tectonic features formed during Tertiary-age slab rollback and pull-apart processes. Comparative analysis with global basins—including Gonghe, Upper Rhine Graben, Buyuk Menderes, Thrace, and Western Canada Sedimentary Basin (WCSB)—demonstrates that the Sunda Basin exhibits competitive geothermal characteristics, particularly in terms of accessible reservoir depth and thermal stability. The basin's offshore setting reduces typical onshore development constraints, offering a strategic opportunity for low-impact geothermal exploitation through re-utilisation of inactive oil wells and modular technologies. This study reinforces the Sunda Basin's role in diversifying Indonesia's geothermal portfolio and supporting national targets for net-zero emissions by 2060.