Controlling factors of abnormal heavy hydrocarbon content in Huoshaopu mine field of Pansyncline

In order to provide a reference for the exploration of coal⁃bed gas， the distribution law of heavy hydrocarbon in the deep part of the Huoshaopu coalfield， the underground gas drainage， and the gas prevention and control in the coal mines， this study tries to find out the abnormal distribution characteristics and control factors of heavy hy⁃ drocarbon in the coals at the Huoshaopu coalfield.Firstly， combined with the previous gas test results of different coal seams， the paper comprehensively analyzed the characteristics of heavy hydrocarbon content in each coal seam by using the techniques of gas geological supplementary exploration， sampling test， gas logging， injection pressure drop test， adsorption and desorption， etc. Secondly， the distribution law of heavy hydrocarbon in the plane and layer domain was analyzed. Thirdly， the correlation between the distribution characteristics of heavy hydrocarbons and various factors such as geological structure， coal seam burial depth， hydrogeological conditions， roof sealing， depositional environment and coal rock quality， as well as coal reservoir in⁃situ rock stress field， permeability and other factors was analyzed. Finally， the formation mechanism and enrichment mode of abnormal distribution of heavy hydrocarbons in the coal seams of Huoshaopu minefield were summarized. The results show that there are a certain amount of heavy hydrocarbon in the gas composition of each coal seam in the mine⁃field， the content of heav⁃ y hydrocarbon is 0.05-7.78 m3 / t， the average is 2.35 m3 / t， the volume percentage is 0.22%-46.93%， the average is 18.42%， and there are local abnormal enrichment sections. The content of heavy hydrocarbon in each coal bed gas is positively correlated with the depth of coal bed. The average content of each lithologic section increases gradually from top to bottom. The heavy hydrocarbon content of Coal 14 is the highest and Coal 3 is the lowest， and the variation of heavy hydrocarbon content from the top to the bottom of the coal seam has the characteristic of “M” type. The ab⁃ normal distribution of heavy hydrocarbon is mainly controlled by structure and source rock， at the same time， it is controlled by such geological factors as hydrogeology， roof lithology， roof rock layer integrity， sedimentary environ⁃ ment， coal， rock and coal， etc. The research results can provide a reference for deep coalbed methane exploration， deep gas extraction and the prevention and control of mine gas disasters. It is suggested that the coal mine and geological exploration should strengthen the measurement of heavy hydrocarbons in the mine gas composition and content test， and the study on its impact on gas outburst，explosion and power generation.