Abstract:

Through observation (Quantang Shaoyang, Beishan Longhui County), measured profile (Jianxincun Lianyuan County and Qixingjie Lianyuan County), sampling and laboratory analysis such as adsorbed gas content, geochemical parameters and reservoir parameters etc. of Longtan & Dalong Formation of Permian in the Xiangzhong depression, we established a composite section of lithologyrock mineralgeochemicalphysical propertiesgasbearing properties of Longtan & Dalong Formation of Permian. The kerogen maceral of the Dalong Formation and Longtan Formation was mainly exinite, vitrinite and inertinite content is less. Samples with total organic carbon greater than 2% accounted for more than 40% of the total longitudinal samples, mainly distributed in the bottom of Dalong Formation and the top of Longtan Formation. The thermal maturity is between 1.10%2.22%, with an average of 1.42% and is at mature to high mature stage. The microreservoir types are mainly mineral micropores and microfracture, followed by organic matter micropore. The mineral micropores mainly include interparticle residual micropores, interparticle dissolution micropores, intraparticle dissolution micropores and intraparticle micropores. Parameters such as thickness of the shale, total organic content, maturity and gas content, oil & gas showing, indicated that the most favorable member for shale gas accumulations is the bottom of the top of Longtan and Dalong Formations with about 80 m thickness which may have good shale gas exploration potential. It is worth noting that shale gas accumulation conditions such as geochemical parameters, mineral composition, reservoir parameters and gas content etc. of the Permian shale in the Sichuan Basin is similar to those in the Xiangzhong depression. They have late peak period of hydrocarbon generation and shallow uplift.The giant Puguang gas field is sourced from the Permian shale. It is needed to pay attention to the transitional facies of shale gas exploration and research of the Permian shale in Sichuan Basin.

Key words: shale gas, transitional facies, Permian, Xiangzhong depression