渤海湾盆地古近系油气富集差异性及主控因素

Differential hydrocarbon enrichment of the Paleogene and its main controlling factors in the Bohai Bay Basin

蒋有录 苏圣民 刘华 王永诗 崔小君

Youlu Jiang Shengmin Su Hua Liu Yongshi Wang Xiaojun Cui

含油气盆地不同地区油气分布层系及富集程度存在较大差异，以统计资料及前人成果为基础，探讨了渤海湾盆地不同凹陷古近系油气富集的差异性及主控因素。研究表明，渤海湾盆地含油气凹陷油气富集类型可归为三类：前古近系型、古近系型和新近系型，以古近系富集型凹陷为主。古近系油气具有“东富西贫”、“不同层系分区性明显”等分布特点，平面上油气集中分布于盆地东部地区富油凹陷，纵向上以烃源岩层系及邻近的沙河街组三段、二段最为富集，向上、向下层段依次减少。多种因素控制了不同凹陷古近系油气差异性富集：凹陷生烃条件从根本上控制了不同凹陷的油气富集差异，盆地东、西部地温场及烃源岩演化的差异是造成“东富西贫”油气分布格局的重要因素，不同烃源岩层系生烃差异性和主力生烃层系、生储盖组合和断层输导作用控制了油气纵向富集层系。

The differences of hydrocarbon accumulation in distribution horizon and enrichment degree are obvious in a petroliferous basin.Based on previous studies, we discuss the differential hydrocarbon enrichment and its major controlling factors of the Paleogene in various depressions of the Bohai Bay Basin.The results show that the petroliferous depressions can be divided into three patterns in terms of hyrdrocarbon accumulation, namely the enrichment patterns of the Pre-Paleogene, of the Paleogene and of the Neogene, with the second pattern taking the lead.The Paleogene hydrocarbon accumulation is characterized by "rich east but poor west" and "high heterogeneity in vertical distribution"-horizontally speaking, hydrocarbons concentrate in the eastern part (rich in hydrocarbon) of the basin; vertically, they mainly accumulate in source rock sequences and the adjacent E and E, and diminish herein upwards and downwards.The diffe-rential hydrocarbon enrichment of the Paleogene in different depressions is jointly controlled by multiple factors:the conditions for hydrocarbon generation are the fundamental one; the differential geothermal fields and source rock thermal evolution are the key to the differential hydrocarbon enrichment of "rich east but poor west"; and the differential hydrocarbon generation potentials of different source rock sequences, major source rock interval, source rock-reservoir-caprock assemblage, and carrier faults, collectively determine the vertical enrichment of hydrocarbons in the basin.

10.11743/ogg20200202