Technology and Equipment of Screen Pipe Protected Borehole of Gas Drainage in Soft Seam

According to difficult drilling of the gas drainage borehole along in soft seam,the short gas drainage distance,low gas drainage effect and other problems,the paper introduced the gas drainage technology with the screen pipe protected borehole,the gas drainage equipment and construction technique in soft seam.With the industrial trial in Dingji Mine,the technical problems of the screen pipe protected borehole down to the depth closed to the borehole depth were solved.A high load pressure,high gas concentration,high flow and high efficient gas drainage was realized.The gas pre-drainage and outburst control effect of the coal mining face were improved.The gas drainage scheduled time in coal mining face was reduced by 28%,the volume fraction of the gas drainage could be improved by 10%~20%.