EVOLUTION OF GEOTHERMAL DIRECTIONAL DRILLING IN INDOENSIA THROUGH FIT-FOR-PURPOSE ENGINEERING WORKFLOWS AND TECHNOLOGY MAPPING

Abstract

Environmentally sustainable growth is strengthening the momentum of the global energy transformation. Renewable energy costs decline, production efficiency improvement and technology advancement are driving the future energy shift within reach. Located in the “Ring of Fire,” Indonesia is home to 147 volcanoes, with 120 of them classified as active. Drilling geothermal wells in this area possesses unique operational challenges from surface to reservoir section. One of the significant challenges faced is the total mud loss circulation, which results in several operational complexities, including insufficient hole cleaning, high torque and drag, and hole instability, leading to a high risk of stuck pipe. Directional drilling companies have become technological partners for geothermal operators in search of solutions to address these problems. Over the past five years, geothermal drilling in Indonesia has seen an exponential learning curve through fit-for-purpose BHA design and technology mapping workflows. Electro-magnetic MWD technology, and high-performance mud motors in aerated drilling, have enabled significant enhancements in operational efficiency. The application of finite element analysis simulators has been instrumental in predicting the directional tendency response of dumb iron BHAs, which, combined with 24/7 operational surveillance through the real-time decision centre has enabled operators to prevent unexpected bit trips and reduce operational risks.
Located 40 km south of Bandung in West Java, Wayang Windu Power Generation is operated by Star Energy Geothermal (SEG) Limited a wholly-owned subsidiary of Star Energy. SEG has drilled more than 45 wells in the Wayang Windu field to supply steam to the two generating unit, namely Unit 1 and Unit 2. In 2019, SEG started a drilling campaign to provide steam as a make-up capacity. The wells were planned to be drilled from the existing pads to aim at subsurface targets that were not vertically beneath the pad. The directional well path had to be designed to penetrate the subsurface targets, and hence steam could be produced as per the subsurface department’s objectives. The well path had to be drillable safely, and casings could be run to each section depth.