Developing low temperature Geothermal projects in Indonesia using pumped well technology

Abstract

Indonesia's installed electrical-grade geothermal capacity is currently limited to developments at high temperature geothermal areas; however, survey data from Badan Geologi (Geological Agency of Indonesia) suggests that a large reserve of medium and low temperature geothermal resources also exists in the country. Using electric line shaft or submersible pumps, low to medium temperature geothermal fluids can be pumped from relatively shallow depths and electricity can be generated using binary power plant technology. This has been proven to be a commercially viable development approach for geothermal systems hosted in a range of geologic settings (e.g., structural/sedimentary basins, volcanic flanks, and metamorphic terranes), and are usually situated in regions of geologic structural complexity. The heat sources for these systems can be the conductive/advective heat transfer from a magmatic body or simply related to deep circulation of fluids in a non-magmatic setting. Lateral outflows of higher temperature geothermal systems are another category of low and medium temperature geothermal resources that may be attractive development targets, potentially allowing for the expansion of presently developed systems. This paper considers the utilization of pumped wells to exploit low and medium temperature resources considering recent trends internationally and with specific regard for the Indonesian context of this technology. As discussed herein, the commercial viability of pumped wells depends on the resource characteristics (namely temperature, depth, well productivity, and gas content) as well as a number of economic and development factors. We present results of modelling the potential productivity in terms of MW/well (net) for pumped wells over a range of permeability and temperature conditions and compare the results with typical high temperature self-flow wells.