Method for changing coal bed gas pre-extraction well into mining well

The invention provides a method for changing a coal bed gas pre-extraction well into a mining well, and belongs to the field of coal bed gas extraction. The method can solve the problem that the gas production rate of a ground coal bed gas well is seriously influenced due to the fact that the number of coal bed gas pre-extraction wells is large due to the fact that the mining activity is damaged.The method comprises the steps that the coal bed gas well in an area which is 0.15-0.3 time of the length of a working face and is close to the air return side of the working face is selected, groundand underground extraction equipment is disassembled, an underground peeping instrument is put into the well to peep whether a sleeve in a shaft is deformed or damaged or not, G-level cement is adopted in the shaft to block the position below a top plate of an excavated coal bed, then perforation is carried out in the shaft with the height being 5 8 times of the height of the upper part of the coal bed, a high-strength sma