Complex Stratigraphic and Structural Evolution of Jabung Subbasin and ItsHydrocarbon Accumulation: Case Study From Lower Talang Akar Reservoir,South Sumatra Basin, Indonesia

摘要

Combined stratigraphic and structural traps of LowerrnTalang Akar Formation (LTAF) syn-rift deposits create arntypical play type in South Sumatra Basin, Indonesia.rnThree field examples from Jabung Block show pop-uprnfeatures caused by Plio-Pleistocene tectonics invertingrnthe pre-existing structures. This phenomenon createsrnthe major hydrocarbon traps in the Jabung (Tungkal)rnsub-basin providing strong targets for further explorationrnwork.rnIncorporating existing 3D seismic and wireline log data,rna tectono-sedimentary model unique for the each fieldrnwas generated. All three field geological models are inrnclose proximity to each other within the Betara Complex.rnGenerally, there are three distinct identifiable sub-basinrnevolution periods. First, a period of horst-grabenrndevelopment controlled by major localized extensionalrnfaults that initiated the basin architecture. This episodernwas followed by rapid to moderate sedimentationrncontrolled by normal faults resulting in deposition ofrnOligocene Talang Akar alluvial, fluvial and deltaicrndeposits. Secondly, a period of decreased fault activityrnalong with regional subsidence coinciding with therndeposition of post-rifting fine marine Miocene sedimentsrnwhich provided a regional seal for the underlyingrnreservoirs. The third period is marked by regional upliftrnresulting in wide spread basin inversion over the entirernregion providing a period of hydrocarbon trapping.rnBasin evolution provided complex stratigraphic andrnstructural features and constitutes compartmentalized　reservoirs. Complex-multiple gas and oil contacts andrnvariation in CO2 distribution has verified the complexityrnof the basins geological framework.rnDrainage patterns identified from localized paleogeographicrnconfigurations can be used to locaternsedimentary styles and trends. When combined withrnattribute extractions and structural analysis, thesernpatterns can help explorationists develop excellentrnopportunities for further exploration and development ofrnthe area.