Technical models and practices of coal and gas co-mining across the full life cycle of outburst coal mines

With the increase of coal mining depth, more and more mining coal seams are gradually turned into outburst coal seams, which have the characteristics of complex geological structure, no mining protection layer, low permeability, high ground stress, etc., and it makes the coal seam gas extraction difficult. For example, in Yangquan Mining Area, from the perspective of co-mining of coal and gas, the laws of gas enrichment, pressure relief and migration at various stages before, during and after mining are analysed. The whole life cycle gas resource extraction technology and equipment system of coal mine is established, which is represented by the technology of ground vertical well fracturing and pre extraction in the complex structural zone of the coal mine planning area, the technology of liquid carbon dioxide phase change and pre splitting blasting and pre extraction in the coal mining development area, the technology of secondary hole sealing and pre pressure relief in the coal mine production area, and the technology of gas surface drilling and extraction in the abandoned goaf. The research results show that the whole life cycle gas resource extraction technology of coal mines with the means of artificial permeability enhancement and mining pressure relief has increased the single-well extraction of ground vertical wells in the coal mine planning area of the Yangquan Mining Area by 7 times. Coal seam gas extraction volume has increased by 5.7 to 8 times, coal mine production area working face advanced pressure relief gas extraction volume has increased by 184%, and the surface drilling gas production in abandoned goafs has reached an average of 3504 m³/d, which effectively improving deep coal mining. The research results will help coal mine enterprises to conduct scientific gas drainage planning from the perspective of the whole life cycle of the mine, so as to promote the utilization of gas resources and prevent the occurrence of gas disaster accidents.