TECTONOSTRATIGRAPHY STUDY OF THE OMBILIN BASIN, WEST SUMATERA BY UTILIZING SUBSURFACE DATA

• Main Author: Faisal, Reno
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/44234
• Institution: Institut Teknologi Bandung

The study area is within the West Sumatera province and located east of Sawahlunto Town. It is about 780 km2 wide dominated by relative plain topography and a small area of ridges in the south. The Ombilin Basin is situated within Barisan Mountain in Sumatera Island that trending northwest – southeast. The basin, at present day, is categorized as an intermountain basin. Six exploration wells and a total of 87 seismic lines acquisited since the beginning of 1980’s were utilized to investigate much further on The Ombilin Basin’s subsurface structure condition. Based on the subsurface interpretation, four tectonostratigraphy units can be identified; pre-rift, early syn-rift, syn-rift and post inversion sediment. The results of well correlation, seismic interpretation and seismic characterization of five horizons; Brani, Lower Sangkarewang, Upper Sangkarewang, Sawahlunto and Sawahtambang which are combined with the generated isochrone/isopach maps, electrofacies and seismic facies analysis reveal the general picture of paleogeography of each interval from Eocene to Early - Middle Miocene. Seismic interpretation is not carried out on top of Ombilin horizon since it is heavily uplifted and eroded. Hydrocarbon discoveries, particularly gas, show that The Ombilin Basin is a prolific basin to be explored extensively to get a new reserves to provide as commercially energy source to develop in local area. The result of subsurface mapping and petroleum system analysis indicates the presence of potential gas accumulation in a closure in the updip layer in the southern part of the basin.