Gas extraction and coal seam water injection integrated dynamic pressure hydraulic hole sealing device and method

The invention discloses a gas extraction and coal seam water injection integrated dynamic pressure hydraulic hole sealing device which is assembled in a gas extraction drill hole. Comprising a head screen pipe, a front-end water absorption expansion rubber hole sealing plug, an extraction pipeline, a rear-end water absorption expansion rubber hole sealing plug, a water injection pipe, a tee joint, a pressure sensor, an electromagnetic valve, a PLC, a data transmission line, a water supply main pipe, an extraction main pipe and a gas-water separator. According to the principle that the isolation positive pressure water ring belt blocks gas, a circle of isolation positive pressure water ring belt is formed around the drill hole, meanwhile, under the effect of stable water pressure, automatic adjustment, automatic adaptation and blocking of air outside the drill hole from entering an extraction system can be achieved, and the situation that a solid hole sealing material forms a gas leakage channel due to drying