Shale Gas Exploration Potential Of Permian System Longtan Formation In Hunan And Hubei Region

In this paper,the main study object is the shale of Permian System Longtan Formation in Hunan and Hubei region.This paper combines and collects the data from previous previous scholars and experts in this area.Learning and studying the geological background of work district,the distribution features of shale,organic geochemical characteristics,reservoir characteristics,gas bearing characteristics and shale gas exploration potential,etc,through methods such as sample collection and analysis assay.Some achievements and understanding of the shale gas in the shale of the Permian system Longtan Formation in Hunan and Hubei region were obtained.The distribution features of shale and the shale thickness of the Longtan Formation of the Permian in Hunan and Hubei region are affected by the geological tectonic movement and sedimentary environment,resulting in different developmental degrees of the shale in the Longtan Formation.The total shale thickness of the Longtan Formation in the Hunan and Hubei region ranges from 0 m to 222.5 m,with a wide range of changes,and the general trend of the thickness of the Longtan Formation in the northern part gradually increases toward the south.The buried depth of shale of the Longtan Formation of the Permian in the Hunan and Hubei region is relatively large,ranging from 61m to 4604m with an average depth of 465.84m.As a whole,it shows a deeper northern burial pattern and a shallower southern distribution pattern.In terms of geochemical characteristics,the distribution of TOC in the Longtan Formation in Hunan and Hubei is extremely irregular,with an average TOC of 2.08%.The TOC of most areas is between 1.0%and 3.5%.The organic matter is mainly type?.The average vitrinite reflectance in Hunan and Hubei is 2.06%,and the vitrinite reflectance in most regions are between 1.0%and 3.5%.The larger the vitrinite reflectance is in the southern part of Hubei,the middle Jianghan Basin in south central and southeast of Hunan region.The content of mineral components in mud shale in Hunan and Hubei region is relatively different.The majority of mud shales are dominated by clay minerals with an average of 40.36%,and the average brittle minerals such as quartz and feldspar have an average content of 35.47%.The average content of other minerals is 24.16%.The micropore and microfissure in the shale of the Longtan formation in Hunan and Hubei region are well developed.the porosity is generally greater than 2%,and the shale permeability is low,with an average of 0.439×10^-3m D.The adsorbed gas content measured by isothermal adsorption experiment is about 2.78 m³/t,indicating a high adsorption ability.Based on existing research,the shale gas exploration potential of the Longtan Formation of the Permian in the Hunan and Hubei region was considered through comprehensive analysis of factors such as the buried depth of mud shale,the thickness of mud shale,the abundance of organic matter,and organic matter maturity.Based on the analysis,five of the perspective regions to explore were selected and distributed in northwestern Hubei,central Hubei,central Hunan,southern Hunan,and southeastern Hunan.