白云深水区油气成藏动力条件研究

特殊的凹陷结构、沉积充填及其演化历史使得南海北部白云深水区具备了成为大型油气区的成盆—成烃—成藏条件。裂陷阶段发育了文昌—恩平组烃源岩(成盆期)、裂后沉降阶段生成大量油气(成烃期)、新构造运动阶段油气大规模聚散(成藏定型期)是白云深水区的石油地质特征。现今为正常压力系统,但地层压力数值模拟结果表明白云凹陷曾经有过异常超压和泄压释放旋回;凹陷内存在大型晚期底辟构造和晚期断裂;白云北坡天然气成藏明显受到晚期断裂控制。综合认为,晚期断裂和底辟带控制了白云深水区的油气运移和成藏。

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.