Simulation of oil-gas migration and accumulation in the East China Sea Continental Shelf Basin: a case study from the Xihu Depression.

The oil-gas accumulation process is a tectonic indicator, and the oil-gas trap is generally a result of tectonic movement. In order to explore the law of oil-gas migration and accumulation in the East China Sea Continental Shelf Basin, this paper analyses the dynamic process of hydrocarbon accumulation based on a geological model, taking the Xihu Depression as an example and using the IES PetroMod basin modelling software. Combined with the seismic data and drilling data, the burial history, thermal evolution history and hydrocarbon generation, expulsion and migration history of the Xihu Depression is simulated in this study. The simulation results show that (1) the tectonic framework of the Xihu Depression developed as an inversion structure from an early extensional stage or transtensional faulting stage to a later compressional or transpressional inversion stage; (2) the Pinghu and Huagang formations of the Xihu Depression are still currently at the peak stage of oil-gas generation, and the Xihu Depression is a depression which has abundant hydrocarbon generation and expulsion at a later stage; (3) oil-gas resources vertically migrated to the structural highs from the eastern and western sub-sags along faults and ultimately accumulated in favourable traps, which developed a migration pattern of interbedded sandstone-fault-sandstone like an upward 'staircase'. In particular, faults and the potential energy state played an important role in hydrocarbon migration of the Xihu Depression, which has a guiding significance for understanding hydrocarbon migration and accumulation law and reducing the risk in oil-gas exploration in the East China Sea Continental Shelf Basin. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]