Volcanostratigraphy of Hululais Geothermal Field, Bengkulu, Indonesia

Abstract

Hululais geothermal field is one of the exploration geothermal fields operated by PT Pertamina Geothermal Energy (PGE). It is located in Rejang Lebong district, Bengkulu province, Sumatra Island, Indonesia. Regionally, this field situated within Bukit Barisan Mountain range on the western side of an overlapping of two major fault segments. They are called Ketahun and Musi Segment. These are two segments of the Great Sumatran Fault complex.
In 2018, geological mapping was carried out to update the data of Hululais volcanostratigraphy by PT PGE. 24 wells were successfully drilled to complete the exploration and development drilling stage on this field. Based on data from surface geological mapping, subsurface (borehole data such as cuttings, cores and borehole image), remote sensing, and some updated modification reports from the previous researchers, Hululais field is part of the quaternary Hululais Volcanic Complex (HVC) from quaternary.
The field comprises six main units (Bukit Resam, Suban Agung, Bukit Beriti, Bukit Gedang, Bukit Lumut and Bukit Pabuar) with associated primary/secondary deposits.