HYDRAULIC CUTTING SEAM AND MULTISTAGE COMBUSTION SHOCK WAVE COMBINED COAL-FRACTURING GAS EXTRACTION METHOD

摘要

A hydraulic cutting seam and multistage combustion shock wave combined coal-fracturing gas extraction method, comprising: cutting slots in an impact bore hole by using hydraulic slotting equipment; performing pressure relief and permeability enhancement on a coal body and enlarging an N₂ or CO₂ storage space; injecting a large amount of N₂ or CO₂ into the bore hole by means of a high-pressure gas cylinder and a pressure reducing valve through a gas injection and extraction pipe (6); injecting a certain amount of methane and dry air into a high-temperature and high-pressure combustion chamber (1) by means of the high-pressure gas cylinder and the pressure reducing valve, so that the gases are mixed and combusted to form high-temperature and high-pressure shock waves; and pushing a piston to compress the N₂ or CO₂, so that a large number of cracks are generated on the coal body around the impact bore hole under the guiding action of the slots. After shock waves are repeatedly generated to form multistage impact, and the impact of the next stage is based on the impact of the previous stage, so that the cracks on the coal body around the bore hole are further expanded and run through. After the N₂ or CO₂ is compressed by means of the multistage impact, more fracture networks are formed on the coal body around the bore hole under the guiding action of the slots and the cracks, thereby enhancing the bore hole-based efficient gas extraction.