HIDROCARBON POTENTIAL OF TALANG AKAR AND GUMAI FM. SHALE, SAROLANGUN AREA, SOUTH SUMATERA BASIN

• Main Author: Raudatul Akmal Lubis, Peri
• Format: Theses
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/48116
• Institution: Institut Teknologi Bandung

Area of interest is located at near the northwestern boundary of the South Sumatera Basin. Oil seep finding on the northern area close to Pegunungan Dua Belas initiated exploration activities and followed by subsequent drilling targetted sandstone of Talang Akar Formation, Baturaja Limestone Formation. and Air Benakat Formation. The oil and gas exploration was begun since 1970. However, exploration activities ended up with no comercial hidrocarbon accumulation and the status of the wells are plug and abandoned. Based on that condition, it is interesting to study geological and hydrocarbon occurance aspects of the area. The Talang Akar and Gumai Formation are trangressive rocks deposited in Late Oligocene to Early Miocene. These rocks are considered generally as proven and potential source rocks, reservoirs and also seal of South Sumatera Basin petroleum province. This study is based on the interpretation of wireline log patterns from seven (7) wells, supported by existing two dimensional seismic reflections, some biostratigraphic and a few geochemical data derived from cuttings and side wall cores. Methodology that has been using in this research are sequence stratigraphy analysis, organic richness calculation based on Passey’s dlog R method using combination of sonic and resisitivity logs and hydrocarbon occurance and accumulation analysis. The study identified four third-order sequences based on stratigraphic positions of Talang Akar and Gumai Formation interval. Passey’s dlog R calculation showed Transgressive System Tract (TST) or Highstand System Tract (HST) deposits have higher TOC calculation than Lowstand System Tract (LST) deposit. Shales from older sequences 1, 2 and 3 have higher potential as source rock than the younger sequence, 4. The hydrocarbon accumulation is identified by stratigraphic trapping. Oil and gas analysis on well TBY is concluded that Lowstand System Tract 3 (LST3) as a current oil and gas reservoir enclosed by Highstand System Tract 2 (HST2) and Transgressive System Tract 3 (TST3) deposits which are having good TOC quality.