Technology of precise control of oil-type gas and engineering practice in coal mine with coal-oil-gas coexistence

Oil gas is a new concealed disaster-causing geological body in coalmines with coal-oil-gas coexistence. During coal and oil gas geological exploration,few attentions is paid to the oil gas stored in coal-bearing strata,while the mine production is facing with the actual threat of oil gas emission. Oil gas disaster has become a difficult problem which can’t be avoided and urgently needed to be addressed for safe and efficient mining in coalmines with coal-oil-gas coexistence. Aiming at the key problems of oil-type gas reservoir occurrence prediction,oil-type gas emission space-time law and oil-type gas control of drainage,by means of theoretical analysis,test,numerical simulation and engineering test,to research precise control technology and engineering application of oil-type gas in typical coalmines with coal-oil-gas coexistence. The findings suggestion：there are four oil-type gas reservoirs,which are continuous and stable distribution in the 50 m excavation disturbed area of the roof and floor of coal seam in studying area (sandstone of the first member of Zhiluo formation,Qili town sandstone of the second member of Yan’an Formation,sandstone of the lower part of Fuxian formation and sandstone of the top part of the Wayaobao formation). The pressure relief oil gas can be extracted effectively by drilling holes in the inner floor from 22.24 m to 33.26 m (average 25.77 m) and from -0.23 m to-65.14 m from the working face. Basic directional long bore hole，the precise three-dimensional comprehensive drainaging model of oil-gas is explored for pre-drainaging,pressure-relief drainaging and pressure-relief drainaging during mining and drainaging in the goaf after mining. The engineering practice shows the average concentration of CH4 decreases from 0.81% to 0.48% in the upper corner of the working face after drainaging,and no abnormal oil-type gas emission and CH4 concentration exceeding the limit occurred in the working face during mining. A set of precise control technology system suitable for coal-oil-gas coexisting mine is formed,which include oil-type gas occurrence,gushing and drainage. It provides theoretical guidance and technical support for the prevention and control of oil-type gas disasters in coal-oil-gas coexisting mine.