Study On Geological Controlling Factors Of Residual Gasredistribution Of Main Mineable Coal Seam In Xu Tuan Mine

In this paper,Xutuan Coal Mine is used to the research area,on the basis of general analysis and summary of tectonic development features and gas occurrence characteristics of Xutuan mine.Taking the 3₂ coal seam as the major research object,by mercury injection,isothermal adsorption,optical microscope and permeability experiment of coal in research area,the characteristics of physical property of coal reservoir and permeability development in the research area were discussed.The characteristics of gas occurrence in 3₂ coal seam are analyzed and the influence of various geological conditions on original gas occurrence are discussed.Induction and summarization on after drainage residual gas of 33 mining area in 3₂ coal seam,the residual gas distribution characteristics were obtained,the control factors of residual gas redistribution are discussed.The analysis shows that the pore structure of the study area is mainly microporous,the transition pore is second,and the mesopore and macropore are poorly development.Because the tectonic coal is relatively developed,the pore size structure and pore shape of coal in research area are obviously different.Fracture of coal rocks for average length of 344/cm²,the average of length and width is 2173?m and 27.3?m,Only 6.3%of the fissures were fil ed.The study area of coal rocks adsorption volume average of 9.9306 cm³/g,the average adsorption pressure of 1.404MPa.The permeability of coal rocks is negatively correlated with the effective stress,and positively correlated with gas pressure.According to the analysis of the condition of the original gas occurrence,the buried depth of coal seam is the main controlling factor of the original gas occurrence.By structural quantitative comprehensive evaluation of the study area,the results show that the maximum value of tectonic complex index is concentrated around the F5 fault,and the gas content of the raw coal around the F5 fault is reduced.The basic area of the top and bottom of the study area is poorly permeable mudstone,which is favorable to the coal gas and the gas content has a good correlation with the thickness of coal seam.The research shows that the residual gas redistribution characteristics in the study area are controlled by geological conditions such as structure,coal seam depth and coal thickness.In the study area,the fault is more developed and the small fault is the most developed.The residual gas content is affected by the structure,mainly due to the development of the small fault.The deeper the coal seam is deeper,the greater the difference in the gas content before and after the mining.Effectively reduce the residual gas content;thicker coal thickness,the greater the difference between the gas content;underground activity area and near the roadway residual gas content and residual gas pressure is low,is not conducive to the occurrence of residual gas.The ratio of CO₂ in the gas component decreased and the ratio of N₂ increased after the extraction.