Further Gravity Data Process to Estimate Geological Structure in Tulehu Geothermal Field, Ambon Island

Abstract

Tulehu geothermal field in Central Maluku, managed by PT PLN since 1997, is targeted for a 20 MW power plant by 2025/2026. Initial exploration, including five wells drilled from 2011 to 2018, yielded unsatisfactory results. This study revisits gravity survey data from 2010 and process additional 2019 gravity data focused on the Banda and Banda Hatuasa Faults to refine the structural understanding of the field. Gravity data processing involved complete bouguer anomaly (CBA) mapping and spatial derivatives. The analysis indicates a gravity anomaly pattern decreasing from SW to NE, suggesting a basement elevation drop across the field. First Horizontal Derivative (FHD) emphasize fault boundaries, and Euler Deconvolution points to structural dip directions. Results confirm the Banda Fault as the primary control for geothermal fluid flow, although it appears slightly southward of prior interpretations. The Banda Hatuasa Fault, contrary to earlier assumptions, is identified as a distinct structure north of the Banda Fault. These findings provide essential insights for targeting faults in future drilling plans, enhancing geothermal resource development in Tulehu.