marine shale gas in the Lower Paleozoic of Sichuan Basin and its periphery: A case study of the Wufeng-Longmaxi Formation of Jiaoshiba area

Abstract：The formation conditions of marine shale gas in the Wufeng-Longmaxi Formation of Jiaoshiba area were evaluated in this paper on the basis of drilling, seismic survey and sample experiment data. The major factors controlling the accumulation and high productivity of marine shale gas in the lower paleozoic of Sichuan Basin were analyzed. The results show that shales of Longmaxi Formation in Jiaoshiba area are characterized by thick formation, good type, high levels of thermal evolution of organic matter, good physical and gas-bearing properties, suitable preservation condition and fracability. Meanwhile, the development and preservation condition of organic-rich shales, natural fractures development and crushability of the shales constitute the major factors controlling the accumulation and high productivity of marine shale gas in the lower Paleozoic strata of Sichuan Basin and its periphery. As abundant materials were provided by the development of organic-rich shales for shale gas generation and storage, suitable preservation conditions seem to be the key factor for accumulation and high productivity of shale gas. Natural fractures and crushability have guaranteed high productivity of shale gas.