Abstract
The onshore and shallow marine conventional hydrocarbon resources around the world are mostly at the maturation phase and hence, exploration activity globally, showing increasing interest into progressively deeper water hydrocarbon prospects such as South China Sea basins. However, a comprehensive understanding of basin tectonics, depositional history, and petroleum systems of the basin is required to deduce the exploration prospectivity of these deeper reservoirs. The Sabah Basin is a prolific hydrocarbon province in Southeast Asia and has a significant economic impact on this part. Recent discoveries in the deep-water hydrocarbon prospects in the NW Sabah Trough prompted a comprehensive investigation of the surrounding area, e.g., Dangerous Grounds for hydrocarbon prospectivity. Previous studies in the Dangerous Grounds mainly focused on the sparse 2D seismic and gravity-magnetic data analysis. A systematic review of stratigraphic evolution has not been presented thus far in the published literature. In this paper, recently acquired high-resolution 3D seismic data with the core and cuttings and conventional well log data from the adjacent areas have been combined to characterize the stratigraphic evolution of the Dangerous Grounds in the NW Sabah Platform. Seven horizons interpreted from the 7570 sq. km 3D seismic data, calibrated with the global sea - level curve and geological time scale, to establish the stratigraphic evolution in the study area. Based on distinct structural and seismic characteristics, and calibrated with the adjacent regions well data, two mega-sequences, namely, lower syn-rift and upper post-rift mega-sequences, have been identified and evaluated. The Paleocene to Early Oligocene syn-rift sequence consists of clastic sedimentary fill in grabens and half-grabens is overlain by Late Oligocene to recent post-rift sedimentary successions represented by siliciclastic and carbonates deposits. Major depositional units within these two mega-sequences, including carbonate, channel, mass transport deposits, and turbidites have been identified and evaluated. During Late Oligocene to Middle Miocene, the area has witnessed the deposition of carbonate platform and reefs on top of pre-existing structural highs. Late Oligocene to Middle Miocene channel-levee complexes with convex upward sand filling features is prominent in the seismic data. Mass Transport Deposits and turbidites have also been observed above the Middle Miocene Unconformity with distinct seismic characteristics. The pelagic and hemipelagic nature of the sedimentary succession deposited from Pliocene to recent in a passive margin condition have also been interpreted from their unique seismic features. Paleocene-Early Oligocene syn-rift siliciclastic hydrocarbon play, Late Oligocene-Middle Miocene carbonate play, and Late Miocene turbidite play within the study area have been interpreted.
Published Version
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