Spray sealing technology for gas extraction drilling

The sealing quality of extraction drilling is the key factor affecting gas extraction and outburst elimination. In order to solve the problems of poor quality of passive hole sealing, low gas concentration in drilling and extraction, and cumbersome process of active hole sealing, a spray sealing technology for gas extraction drilling is proposed. After the drilling construction is finished, a pneumatic deep-hole centrifugal spray cup type high-rotation speed spray nozzle is sent to the preset position of the drilling hole, and a hole sealing material preheating system is started at the same time. When the temperature of the spray type hole sealing material is stabilized at 70-80℃, a pneumatic suction pump is started to suck the sealing material, and the sealing material is mixed and sprayed out through the spray nozzle and solidified on the inner wall of the drilling hole. The four-quadrant slide structure system guides the nozzle to move from the bottom of the hole to the mouth of the hole to complete the spray-type sealing operation. Finally, the PVC plug of 2.0-3.0 m is fixed with the polyurethane foam material at the drilling hole, and then the extraction system is connected. The field application results show that the new spray sealing material has the advantages of liquid quick setting, good sealing performance, strong adhesion, flame retardant, high toughness and high strength, etc. It can react and solidify quickly in the gas extraction hole, and form a flame retardant sealing film with high strength and toughness. The use of spray sealing technology and equipment can realize automatic sealing of coal seam drilling. Compared with polyurethane sealing technology, the volume fraction of gas extraction after applying spraying-type sealing technology is increased by 19%, the cost of single-hole sealing is saved by 53%, and the sealing time of single-hole is saved by 50%.