Comparative Study on Sealing Technology of Gas Drainage Borehole in Soft Coal Seam

This paper discusses four kinds of hole sealing technologies for gas drainage in soft coal seam, which are polyurethane hole sealing, cement mortar hole sealing, full-length screen pipe hole sealing and pipe direct connection technology. Through the observation of negative pressure loss, the sealing effect of four sealing technologies is analyzed, the polyurethane sealing effect is poor, the cement mortar, the full-length screen pipe combined with cement mortar and the direct connection technology of pipe are good; through the observation of gas concentration, the gas drainage effect of four sealing technologies is analyzed, the polyurethane sealing technology is the worst, and the direct connection technology of pipe is the worst. The gas drainage effect is the best; according to the sealing effect and gas drainage effect, the traditional polyurethane and cement mortar sealing technology cannot meet the gas drainage demand of the soft coal seam. In the case of slow drilling deformation, the full-length screen pipe sealing technology can be used. In the case of rapid drilling deformation, the direct connection of pipe sealing technology should be used.