Resource Potential Evaluation Of Shale Gas In Shanxi Formation In Qinshui Basin

This paper takes mud shale of Shanxi Formation in Qinshui Basin as the research object,and analyzes the resource potential of shale gas in Shanxi Formation.Through the research of shale gas at home and abroad,the mud shale distribution characteristics,organic geochemical characteristics,mineral composition features,pore fissure development characteristics,porosity and permeability characteristics of mud shale in the study area are analyzed by using organic geochemistry experiment,X ray diffraction method,scanning electron microscopy,nuclear magnetic resonance and low temperature nitrogen adsorption experiment.Finally,the favorable areas are selected based on the favorable area evaluation parameters,and the shale gas resources in favorable areas are preliminarily calculated.According to the research results,the Shanxi Formation in Qinshui Basin is dominated by continental lake facies and continental lacustrine deltaic sedimentary systems.The average thickness of mud shale is 25.83m and the average depth of mud shale is 686.2m.The total organic carbon contents of mud shale in the Shanxi formation are higher,the total organic carbon of mud shale is ranged from 0.91percent to 5.91 percent,with an average value of 2.48 percent.The organic matter types of mud shale are typical type III kerogen.The results of organic thermal maturity text showed that vitrinite reflectance of mud shale is ranged from 1.51percent to 2.45 percent,with an average value being 2.03 percent.It is not difficult to find that the mud shale of Shanxi Formation of Qinshui Basin has certain generation conditions of shale gas.The XRD analysis results indicated that the contents of detrital mineral in Shanxi Formation mud shale of Qinshui Basin are 40.85 percent on average,and the contents of clay mineral in Shanxi Formation mud shale of Qinshui Basin are 58 percent on average.The higher clastic mineral content of mud shale shows that it has strong brittleness and is beneficial to generate fracture by hydraulic fracturing,and the higher clay mineral content indicates that the micropore of mud shale is more developed.The results of porosity text showed that porosity of mud shale is ranged from 2.15 percent to 6.95 percent,with an average value being 4.1 percent.The results of permeability text showed that permeability of mud shale is ranged from0.043 millidarcy to 4.546 millidarcy,with an average value being 1.508 millidarcy,so the mud shale of Shanxi Formation in Qinshui Basin has poor physical property.Based on the isothermal adsorption experiment,the gas content of mud shale is ranged from 1.25m~3/t to 2.52m~3/t,with an average value being 1.60m~3/t,the mud shale of Shanxi Formation in Qinshui Basin has good gas-bearing properties.It is not difficult to find that the mud shale of Shanxi Formation of Qinshui Basin has certain reservoir conditions of shale gas.Combing with the preferred criteria of shale gas favorable areas in the study area,this paper selects two favorable areas.The shale gas resources of one favorable area in the middle part of the north is 105.04 billions cubic meters,and the shale gas resources of another favorable area in the south part of the central part is 35.054billions cubic meters.The large amount of resources shows that the Shanxi Formation of Qinshui Basin has a certain potential of shale gas exploration.