渤海青东凹陷中部地垒带油气成藏条件与成藏模式

在渤海南部青东凹陷中部地垒带开展油气成藏条件和成藏模式研究。结合岩石薄片鉴定、岩石热解、饱和烃气相色谱、芳烃色谱-质谱、流体包裹体测试分析和构造-热演化历史模拟等手段,分析青东凹陷中部地垒带的油气成藏条件,建立油气成藏模式,揭示油气成藏特征。研究结果表明:青东凹陷中部地垒带以沙三下亚段和沙四上亚段半深湖相暗色泥岩为主力烃源岩,储集层为沙三段展布范围广、储集性能优越的扇三角洲前缘滩坝砂体,具有北次洼和中次洼双洼供烃、凹中垒近源混合充注、晚期成藏的特征。研究区具备良好的生储盖组合,成藏模式具有“近源捕集,晚期大规模成藏”的特点。

Hydrocarbon accumulation conditions and accumulation models in the central horst zone of Qingdong Sag,south Bohai Sea,China

Combined with the methods of rock thin section identification,rock pyrolysis,saturated hydrocarbon gas chromatography,aromatic hydrocarbon chromatography-mass spectrometry,fluid inclusion test and analysis,and tectono-thermal evolution history simulation,the conditions of hydrocarbon accumulation in the central horst zone of Qingdong depression are analyzed and the hydrocarbon accumulation model is established so as to reveal the characteristics of hydrocarbon accumulation in the area.The results show that the main source rocks in the central horst belt of Qingdong sag are the semi-deep lacustrine dark mudstone in the lower member of Es3 and the upper member of Es4.The third member reservoir is a fan-delta front beach bar sandbody with wide distribution and superior reservoir performance,characterized by double sag hydrocarbon supply in the north and middle subsag,near source mixed charging in the middle barrier of the depression,and late hydrocarbon accumulation.The study area has a good source-reservoir-cap assemblage,and the reservoir-forming model is characterized by“near source capture and large scale accumulation in late period”.