Expediting Geothermal Exploration in Indonesia: Should We Consider Slimhole Drilling?

Abstract

The Indonesian government has just revised the national target for the utilization of geothermal energy from 7,200 MW in 2025 to 7,000 MW in 2030. Unfortunately, this revision does not necessarily eliminate the main challenge of geothermal development, which is the slow-going exploration activities. Several factors have been identified as possible causes that hinders the geothermal exploration activity in Indonesia, one of them is the high resource risk. This high risk is due to the investors must invest a large amount of capital for drilling activities while the subsurface uncertainty is still very high. The high upfront drilling cost is influenced by many factors, one of which is the type of well chosen (e.g. big, standard, or slim hole well). Even though slimhole well is cheaper than standard/big hole, the current trend of geothermal industry in Indonesia is to use standard or even big hole for exploration drilling. Moreover, slimhole is considered to possess many disadvantages such as longer drilling operation days and difficulties to be used as production well. One emerging question is that whether slimhole should be considered by geothermal developers in Indonesia as one option of exploration planning strategy. In order to answer the question, this research conducts literature study regarding the past operation of slimhole drilling in exploration projects in Indonesia. This paper also aims to summarize the results of literature study and brainstorming session conducted by authors for the past several months on the pros and cons of slimhole drilling for geothermal exploration with regards to current state of Indonesia energy industry as the context. Finally, this paper is expected to trigger more discussion among geothermal practitioners about when and how to incorporate slimhole drilling into their exploration strategy with the hope of optimizing the acceleration of exploration projects in Indonesia.