Study On Shale Adsorption Characteristics Of The Lower Paleozoic In The Southeastern Sichuan

The southeastern Sichuan area is located in the southeastern part of Sichuan Basin.Some breakthroughs in shale gas exploration has been made.Shale gas flow have been received In the Fuling,Pengshui,Liangping,Yongchuan,Qianjiang and other regions,especially in the Fuling area has entered a large-scale commercial development stage.The Lower Paleozoic in the southeastern Sichuan Basin has mainly developed two sets of shales,such as the Upper Ordovician Wufeng Formation-the Lower Silurian Longmaxi Formation and the Lower Cambrian Qiongzhusi Formation,especially the Upper Ordovician Wufeng Formation-the Lower Silurian Longmaxi Formation.It is an important layer of shale gas in exploration and development of China.In this paper,shales in the Qiongzhusi Formation and Shijingtuo Formation of Lower Cambrian,and shales in the Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation in the southeastern of Sichuan Basin are taken as the research objects.Combining the domestic and aboroad research status,shale samples were subjected to isothermal adsorption test,gas composition analysis,scanning electron microscopy,gas content test,X-ray diffraction analysis,thin film identification,low pressure nitrogen adsorption and other experiments.Gas content characteristics,organic matter characteristics,micro-pore characteristics,petrological characteristics and physical properties of shales in the Lower Paleozoic of southeastern Sichuan Basin were studied.It is found that the adsorption capacity of shale in southeastern Sichuan is good,and the adsorption capacity of shale in each region is relatively stable.However,the adsorption capacity of the shale in different regions and different times is slightly different.Adsorption capacity of shale in the Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation is significantly better than that of the Lower Cambrian shale.By analyzing the influencing factors of shale adsorption capacity,it is found that the abundance of organic matter and specific surface area are the decisive influencing factors of shale adsorption capacity in southeastern Sichuan.Organic matter maturity is also positively correlated with the adsorption capacity of shale.The adsorption capacity of the shale in the study area is not significantly related to the clay mineral.