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

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.