This paper focuses on the analysis of the deposition features,reservoir characteristics and gas-bearing characteristics of the Upper Ordovician Wufeng Formation and Lower Silurian Longmaxi Formation in Sichuan Basin and its peripheral areas.The results of geochemical analysis,mineralogical analysis and isothermal adsorption experiment show that these features of the Wufeng Formation-Longmaxi Formation are as follows.① The sedimentary environment of Lower Longmaxi Formation is deep-water shelf; ② there are five kinds of lithologies,that is,siliceous rock,black shale,siltstone,biological limestone and bentonite; ③ the black shale in Lower Wufeng FormationLongmaxi Formation is characterized by an effective thickness of >50 m,average mass fraction of organic carbon content (TOC) of 3.81%,average maturity of 1.62% and an average mass fraction of 54.94% for quartz mineral and there is a positive correlation between the content of TOC and the content of quartz mineral; ④ the micropores are divided into four categories including the intergranular pore,intragranular pore,organic matter pore and microfracture,and the organic matter pore and the hole between the clay tablets are favorable for the preservation of oil and gas; and ⑤ the Langmuir volume parameter is 1.52~3.01 cm3/g,with an average of 2.33 cm3/g,and organic matter pores in the black shale are the main controlling factors to control gas content.
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