Gas control of low gas permeability seam based on deep borehole fracturing and permeability improved technology with carbon dioxide

In order to solve low effective influence scope of the gas drainage with long deep borehole existed in the gas drainage of low permeable seam, the low g as drainage efficiency, long gas drainage period and other problems, the carbon dioxide fracturing and enhanced permeability improved test and application with 100 m deep borehole was conducted in No.1211 coal mining face of No. 3 seam in Sima Coal Mine to effectively improve the permeability of the seam and to reduce the gas d rainage period. The fracturing test with the 100 m deep borehole was individually conducted in the no gas drainage seam and in the gas drainage seam. A tracer gas m ethod was applied to determine the spacing between the fracturing and permeability improved boreholes in the seam as 10 m. Within 300 m strike scope of No.1211 co al mining face, the application of the fracturing and permeability improved to the deep borehole in the seam showed that the carbon dioxide fracturing of the deep boreh ole could realize the high efficient permeability and the gas replacement in No.3 coal seam. The gas desorption and gas pressure of the seam could be obviously reduc ed. Within 60 days, the seam gas content was reduced by1.8 m3/t averagely, the difficult gas drainage status of the low permeability high gassy seam was improved an d the gas drainage period was obviously reduced.