渤海湾盆地南堡凹陷油气运移路径模拟及示踪

在油气成藏期分析的基础上, 采用盆地流线模拟技术对渤海湾盆地南堡凹陷成藏关键时刻油气运移过程进行了恢复, 根据原油含氮化合物和成熟度指标对典型油气富集区的油气运移路径进行了示踪.油气运移路径模拟结果表明, 研究区南部凹槽源内和源下油气藏在东营末期(距今24.6 Ma)有一期较小规模运移, 油气大规模运移时期为明化镇中期(距今9 Ma).南部凹槽源上油气藏和北部凹槽源内油气藏在明化镇中期有少量油气运移, 大规模运移时期为明化镇末期(距今2 Ma).目前南部凹槽勘探程度较低, 模拟结果表明其具有较大的勘探潜力.原油地球化学指标揭示在源上油气藏富集区, 对于伸入洼陷中心的油源断层, 油气主要沿断层走向, 向构造高部位及断层面两侧砂体运移; 对于平行洼陷中心的油源断层, 油气主要沿断层倾向向构造高部位运移.在源内油气藏富集区, 油气主要通过有效烃源岩层系内发育的砂体向构造高部位运移. 

Reconstructed and Traced Pathways of Hydrocarbon Migration in Nanpu Depression,Bohai Bay Basin

The pathways of hydrocarbon migration in main hydrocarbon accumulation periods of Nanpu Depression in Bohai Bay Basin were reconstructed by the technology of streamline simulation. Based on the data of nitrogen compounds and maturity in crude oil, the traced pathways of hydrocarbon migration in the typical enrichment areas are studied. Streamline simulation results show that to reservoir inside and under source rock in south sags, there was a smaller scale hydrocarbon migration in late Dongying Formation (24.6 Ma ago), and a mass hydrocarbon migration in middle Minghuazhen Formation (9 Ma ago). To reservoir upper source rock in south sags and reservoir inside source rock in north sag, there was a small amount of hydrocarbon migration in middle Minghuazhen Formation, mass hydrocarbon migration in late Minghuazhen Formation (2 Ma ago). At present, hydrocarbon distribution in south sags does not match the simulation results, which indicates greater potential for exploration. The geochemical index of crude oil show that in the enrichment area of reservoir upper source rock, hydrocarbon migration was along faults strike, to the tectonic high position and sandstone on both sides of fault plane when the source fault stretched into the Sag center. For source faults parallel to the Sag center, hydrocarbon migration was along the faults tendency to the tectonic high position. In the enrichment area of reservoir inside source rock, hydrocarbon migration was along sandstone to the tectonic high position.