Geology Fault Network of Hululais Geothermal System, Bengkulu, Indonesia

Abstract

The Hululais geothermal field in Bengkulu, Indonesia is one of the geothermal fields developed by Pertamina Geothermal Energy (PGE), situated on the western side of an overlapping Ketahun and Musi Segment, which is part of Great Sumatera Fault. Morphologically, the Hululais field stand within in Hululais Volcanic Complex (HVC) consisting entirely of Quaternary volcanic rocks. The orientation of structural geology is predominantly northwest-southeast (NW-SE). These structural trends are consistent among surface and subsurface data, fault network, determined from map lineament interpretation, geologic mapping, gravity data and borehole data. The most significant structural features are the Suban Agung Fault (SAF), this master fault strikes northwest through HVC. The northwest trending SAF plays an important role in this system, affect a zone of extension recent volcanism and controls the fluid circulations of Hululais geothermal system.
Ascertain of the fault network in Hululais Geothermal Field (HGF) will assist to define the most productive parts of the zone. Similar fault studies can be applied in other geologic structures to define the most permeable areas in the field.