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Sabah Unveiled: How High Resolution 3D Dual-Previous HitSensorNext Hit Seismic Provides A New Insight Into The Geological Evolution And Petroleum Potential Of Offshore Deep-Water Sabah

Abstract

The first ever multi-client 3D seismic survey was acquired in Malaysia between 2016 and early 2018. The high-resolution, true broadband, dual-Previous HitsensorTop survey covers over 36000 sq km over the offshore Sabah area. The Sabah MC3D survey encompasses the outer Sabah Thrust-Belt, the Sabah Trough and the Sabah Platform area; a south-westerly extension of the Dangerous Grounds. Outboard of the Sabah Thrust-Belt the area remains only marginally explored. Partially due to the deep-water frontier environment, but also due to the multi-vintage, sparse and irregularly spaced 2D data grid that provided just a fragmentary glimpse into the petroleum potential of one of SE Asia’s last frontier areas. The Sabah MC3D survey changed all that and where once the blinds were partly shuttered they are now open. On initial inspection the new seismic data reveals an outboard area constructed of a number of broadly similar NE-SW aligned grabens displaying typical extensional syn-rift geometries. The earliest syn-rift sediments is thought to be Palaeocene-Eocene in age, and is represented by a laterally extensive seismic package displaying parallel, high-amplitude seismic reflectors. This is succeeded by a more seismically monotonous package exhibiting classic multiphase syn-rift geometries. The end of the syn-rift is marked by the drift phase where the continued spreading of the South China Sea led to quiescent conditions and the widespread deposition of Early Miocene platform and pinnacle reef carbonates. The basins are capped by Late Miocene to Recent deep-water sediments as the result of a sudden and rapid drowning of the area. These fine-grained sediments are notably deposited immediately above the Mid Miocene Unconformity (MMU) which developed due to the cessation of SCS spreading as the Dangerous Grounds collided with NW Borneo. But not all basins are created equally. The new seismic data reveals a diverse basin architecture with a clarity not previously recognised. Individual basins present unique geological stories and hydrocarbon play opportunities while adhering to the overall offshore Sabah framework. But which basins offer explorers the greater chance of success? This paper examines some key geological variances between the outboard syn-rift grabens and how seismic analysis of the depositional history and structural evolution of individual basins may provide a key insight into the hydrocarbon prospectivity of the area.