The Influencing Factors And Quantitative Evaluation Of Storage Capacity Of Continental Shale In The Northeast Sichuan Basin

Shale gas is mainly adsorbed and freely occurrence in the shale micro and nano pore.The storage capcity of the shale reservoir is influenced by various factors synthetically.This paper analyzed the Artesian well group of the lower Jurassic of the Yuanba area in the northeast Sichuan on shale geological,geochemical characteristics,mineral fabric features,pore structure and physical properties.By analyzing these features,this paper studied the shale reservoir capacity factorst in terrestrial facies in the northeast Sichuan further.Through the study,This paper found that continental shale of rich organic matter in the northeast Sichuan is mainly distributed on the top Dongyuemiao and Dananzhai.Its shale distribution of organic carbon content is in the range of 0.12%?3.10%,average 1.06%,and organic matter type is given priority to with type?and type?,and Ro distribution ranges of 1.39%?1.93%,average 1.63%,indicating being in the high mature stage.The continental shale in northeast sichuan is mainly composed of minerals and quartz,including clastic minerals such as plagioclase,calcite,potassium feldspar and pyrite,and other authigenic minerals with less content.Among them,quartz content is the highest,with a distribution range of 19.3%?74.3%,with an average of45.56%;clay mineral content is the next,with a distribution range of 18.6%?65.5%,with an average of 40.90%;plagioclase content is relatively low,with an average of3.96%.The average content of calcite reached 9.8%,mainly distributed in the daanzhai section,and the content of other minerals is less than 1%.The reservoir space of continental shale in northeast Sichuan is mainly composed of mineral matrix pores and organic matter pores,the pore volume is mainly contributed by mesopores and macropores,and the pore surface is mainly contributed by micropores and mesopores.Organic carbon content,thermal evolution degree,clay mineral content,temperature and pressure are the important factors affecting shale gas storage capacity.The average pore volume of the evaluation index of continental shale storage capacity in northeast sichuan is 11.56×10^-3ml·g^-1,and the average specific surface area is 9.541m²/g,which is significantly lower than that of the longmaxi formation in southeast chongqing.The reservoir capacity of the study area is affected by the lithofacies.The lithofacies with strong reservoir capacity of the continental shale in northeast Sichuan are the organic argillaceous rich shale and the organic mixed rich shale,which are the dominant lithofacies in the study area.