Assessment of exploration strategies, results and costs of geothermal fields in Indonesia

Abstract

This study evaluates exploration methods, strategies, results and costs of 5 geothermal projects in Indonesia. Observations are compared to reported cases from other leading geothermal countries. Exploration strategy plays an important role in determining success of the exploration stage. Consequently, exploration strategy determines commerciality and is important for decision making at the development stage gate. There is a gap in the Indonesian geothermal industry where significant elements of actual exploration strategies and costs have hardly been published with an actual reference. In this study, exploration methods, strategies, results and expenditures, along with total project costs are collected from feasibility studies, exploration reports and annual reports. Cost indices are used to reflect historical changes. This study adopted quantitative methods that involve descriptivecomparative analysis. Exploration variables are evaluated prior to conducting statistical examination of the findings. In the 5 Indonesian geothermal projects the number of explorations wells ranges from 2 to 10 drilled from 1 to 5 well pads. Exploration drilling success ratio in the 5 projects ranges from 33 to 67%. The power density ranges from 6 to 15 MW/km2 and the recent average exploration well output acquired from 29 wells in the 5 projects is 5 MW/well. The exploration cost in the 5 projects is expected to be in the range 15-40% of the overall planned project cost. This amounts to 0.6-2 million USD per MW which is significantly higher than in reference projects in other countries where the exploration cost was in the range of 0.2-0.8 million USD per MW.