Publications

Palinspastic restoration study has been conducted to evaluate the hydrocarbon traps mechanism in West Natuna Basin (WNB), which is located in the centre of the South China Sea’s Sunda Shelf, bordered by the basement high of the Sunda Shelf to the south, the Natuna Arch to the east, and the Khorat Swell to the north. This study attempts to define the possibility of hydrocarbon traps generation in the area, which is associated with graben initiation, either before or during the main Late Miocene inversion structuring event. Structure map and cross section were generated by integrating wells data and 3D seismic to show the development of multi-phase inversion structures along NE-SW trending grabens and half-grabens that underwent NW-SE Late Eocene-Early Oligocene extensions. Palinspastic restoration shows an evolution of asymmetric anticlines that formed in the hangingwalls of reactivated planar extensional faults and syn-rift strata that formed unique harpoon structures in the inversion anticlines. This structure characteristic shows syn-rift structure development that might be overprinted by inversion structure. Basin modelling indicates that the hydrocarbon expulsion has started during late syn-rift initiation. It creates the chance of hydrocarbon structural trap that has generated as the horst block and roll-over closure. It is filled with the syn-rift sediments as a reservoir and sealed by shale as the post-rift sediments. Seemingly, the inversion structure after rifting also allows the hydrocarbon mechanism trap. Therefore, palinspastic restoration becomes one of the classic approaches which is very useful in understanding deformation process in relation with the trap mechanism. The result indicates that the critical moment of graben inversion-related structure plays a significant role in the critical timing of migration and charging. This study demonstrates that a production field can be mapped and developed more accurately by obtaining a better understanding of the field’s structural evolution, migration history and trap mechanism.