Research on Influence Rules of Gas Content and Water Content in Low Permeability Coal Seam after Repeated Hydraulic Fracturing
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Aiming at the problems of low permeability and poor extraction effect of coal seam in China, hydraulic fracturing repeatedly and effect investigation tests are carried out in low permeability coal seam of No.12 Mine of Pingdingshan Coal Mining Group Corporation. The variation rules of gas content and water content in coal seam(Ji15) are analyzed in detail. The results show that the effect of repeated fracturing on gas content and water content in low permeability coal seam is obvious. The average gas content of coal seam(Ji15) is 63% lower than one of original coal seam within effective range(35m) around fracturing hole, and the average water content of coal seam(Ji15) is 3 times higher than one of original coal seam. By and large, the gas content decreases gradually from fracturing hole to surrounding area, and water content is higher or lower generally in local area. The research results can provide reference for optimization of hydraulic fracturing parameters and extraction holes in low permeability coal seam.
Low permeability coal seam, Repeated hydraulic fracturing, Effect investigation, Gas content, Water content, Influence rule