A study on hydrocarbon accumulation dynamics in Baiyun deep-water area,Pearl River Mouth basin

Baiyun deep-water area,located in the northern South China sea,has favorable conditions of basin formation,hydrocarbon generation and accumulation as a large petroleum province,due to its special sag structure,depositional filling and evolution history.Petroleum geology in this area can be characterized as follows: source rocks of Wenchang and Enping Formations developed during the rifting(basin formation) stage,ample hydrocarbon was generated during the post-rifting(hydrocarbon generation) stage,and oil and gas migrated and accumulated extensively during the neotectonism(fixed accumulation) stage.The pressure modeling results show that there were three cycles of over-pressuring and releasing in the deep-water area,although under a normal pressure system today.Large late diapiric structures and faults occurred within the sag,and gas accumulation was apparently controlled by late faults in its northern slope.In summary,hydrocarbon migration and accumulation are constrained by late faults and diapiric structures in the deep-water area.