Resource Potential Evaluation Of The Carboniferous-permian Shale Gas In Erlian Basin

On the basis of previous research, field investigation and experimental analysis,the article studied the Carboniferous-Permian shale in Erlian Basin, focuses on thecharacteristics of shale distribution, organic matter and reservoir.Arcording to theseanalysis, the resource potential of Carboniferous-Permian shale gas in Erlian Basinhas been evaluated quantitively.The sedimentary environments of Erlian Basin in Carboniferous-Permianwere dominated by marine and transitional facies. The geological setting ischaracterized by low and high depth in the western and eastern section respectively,and zonal distribution inN-S direction, which provided an ideal sedimentaryenvironment for the deposit of shale. Stratigraphic correlation and sedimentaryfacies analysis show that the Carboniferous-Permian shale deposits relativelyextensively in Erlian Basin but the lateral continuity of stratum is poor, the differenceof formation thickness is great.The formation of Linxi, Shoushangou, Amushan and Baoligaomiao arethe favorable reservoirs for shale development. There are two main shaly regions atWest Ujimqin banner and Xilinhaote and a secondary development district at LinxiCounty.Through the analysis of different types of organic matter parameters, andthe factors of high evolution on the type of organic matter degradation, the mainclassification of organic matter in the Carboniferous-Permian shale is type II, and thesource is mainly from higher terrestrial plant.The average content of original organic carbon is0.41%shown bydata recovery of residual organic carbon content, and the peak can reach0.5%, whichcan be found at the upper segment of Shoushangou formation, Linxi formation andZhesi formation.The reflectance of vitrinites is mainly between0.88%~4%, which isat the stage of mature to over mature, showing that Carboniferous-Permian in ErlianBasin had the potential to generate shale gas.The Carboniferous-Permian Argillaceous rocks in Erlian Basin are mainly silty shale and shale, partly metamorphosed into slate by the regional thermalmetamorphism, the effective porosity of rock is extremely low, the majority of whichis only1%, and the permeability is less than0.01×10-3μm2. The quartz content inCarboniferous-Permian shale is relatively higher and stable distribution, ranging from30.8%to51.5%, the average value is35.7%.The natural fracture easily developedwhich is advantageous to the artificial fracturing and is a favorable factor in thedevelopment of high-quality reservoir. Isothermal adsorption experimental datashow that the content of adsorbed gas of Carboniferous-Permian shale is relativelylower; the average adsorption gas content is0.92m3/t.Based on the standard of the evaluation parameters stated in “The assessment ofshale gas resources potential and the standard of area-selection” and its supplementsedited by the Ministry of Land and Resources, the shale gas resource potential inCarboniferous-Permian in Erlian Basin is calculated through the volume method, theP50recoverable resources is1376.91×108m3and these parameters only drop intothe prospective area standards.