河西走廊地区石炭系—二叠系油气地质条件与含油气前景

    Petroleum geological conditions and petroleum-bearing prospect of Carboniferous-Permian strata in Hexi Corridor region

    • 摘要: 对河西走廊地区石炭系—二叠系沉积演化、生烃条件、储集条件、生储盖组合类型和保存条件进行了研究,认为区内石炭系—二叠系具有良好的油气地质条件,是值得重视的油气勘探新层系。研究区早石炭世—早二叠世早期,以浅海相—海陆交互相沉积为主,前黑山组—太原组发育多套暗色泥岩或炭质泥岩为主的烃源岩,有机质含量中等—较高,以Ⅱ~Ⅲ型干酪根为主,烃源岩演化进入成熟—高成熟阶段;储集层以碎屑岩为主,成岩作用强烈,原始粒间孔隙不发育,但不乏溶蚀孔隙较发育的中等—较好的碎屑岩储集层,而且碳酸盐岩也是区内重要的储集层类;中生界为区域盖层,石炭系—二叠系内部的砂泥岩组合构成纵向上的储盖组合;可形成内生连续式、上生下储式、潜山式等多种生储盖组合类型。石炭系—二叠系广泛分布的油气苗或钻井油气显示,为存在油气生成、运移与聚集的过程提供了依据。

       

      Abstract: Based on a study of the sedimentary evolution, hydrocarbon generation conditions, reservoir conditions, source-reservoir-cap rock combinations and preservation conditions, the authors hold that there exist favorable petroleum geological conditions in Carboniferous-Permian strata of Hexi Corridor region, and Carboniferous-Permian are new strata worthy of attention. The shallow sea-alternative land and marine facies were mainly developed during Early Carboniferous to Early Permian period, forming several sets of hydrocarbon source rocks from Qianheishan Formation to Taiyuan Formation, which are mainly dark shale and carbargillite, with the abundance of organic matter being intermediate to high, with the type belonging mainly to II~III, the evolution stage being mature-high mature, and the stage of hydrocarbon generation being after Cretaceous. The reservoirs are mainly composed of clastic rocks characterized by strong diagenesis, the original intergranular pores are not well developed, but there do exist middle - better clastic rock reservoirs, and the carbonate rock is also an important reservoir type in this area. Mesozoic is a regional cover bed, and the combination of Carboniferous-Permian sandstone and mudstone is a vertical source-reservoir-cap rock combination, with the formation of several source-reservoir-cap rock combinations of endogenetic continuous type, upper generation and lower reservoir type and buried hill type. Widespread oil and gas seepages and oil and gas shows of wells in Carboniferous-Permian strata provide evidence for hydrocarbon generation, migration and accumulation.

       

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