Study on distribution laws of gas and hydrogen sulfide from coal seam affected by abandoned oil wells

This paper is devoted to solve the problem of comprehensive control of coal seam gas and hydrogen sulfide in the mining face within the affected area of abandoned oil wells in the coal mining area resource superimposed mining area.The abandoned oil wells of Matan 30 and Matan 31 in No.Ⅰ0104105 working face of Shuangma Coal Mine were taken as examples.Through the parameter testing，gas composition analysis， and field investigation， the source， distribution， and influence range of gas and hydrogen sulfide in coal seam in the affected range of abandoned oil well were studied.The results show that，the coal-bearing strata in Shuangma coal field belong to the coal-oil coexistence strata，and the emission of H2S gas in the local area of the working face is mainly affected by the closed and abandoned oil Wells.Within the influence range of abandoned oil well， along the direction of working face， the closer to the oil coal center， the higher the concentration of CH4 and H2S gas in the borehole， and the two sides of the oil well show a decreasing trend.In the affected area of abandoned oil well， the distribution of the desorption gas content in coal seam along the center distance of oil well presents a trend of decreasing power function.The closer the working face is to the center of the oil well， the higher the concentration of CH4 and H2S， and the lower the concentration when the working face is moving away from the oil well.The influence radius of CH4 and H2S gas on the coal seam in the affected area of Matan 31 abandoned oil well is over 300 m.The results provide a theoretical basis for further understanding the law of gas and hydrogen sulfide enrichment in the mining face and the design of treatment measures within the influence range of abandoned oil wells.