The invention discloses a method for extracting residual
coal bed gas in multiple
layers of goafs by drilling a well from the ground and penetrating through residual
coal pillars. The method comprises the following steps: drilling the well from the ground to the construction floor of the residual
coal pillars, and penetrating through all the residual coal pillars; when the residual coal pillars are relatively narrow, drilling the well from the ground, penetrating through the residual coal pillars, and then directly connecting with the goafs; when the residual coal pillars are relatively wide, drilling the well from the ground, penetrating through one of the residual coal pillars to a bottom plate of the residual
coal pillar, inserting a steel
pipe, which is externally fixed with a high-pressure bag, to the bottom of the residual
coal pillar into the well from the ground, connecting a high-pressure hose with the high-pressure bag to extend to the ground, pressing water into the high-pressure bag through the high-pressure hose to form a hole-sealing section, then injecting high-pressure water into the well through the steel
pipe, fracturing the residual
coal pillar, and then draining and depressurizing the high-pressure bag; continuously penetrating through the other residual coal pillars, inserting an extraction
pipe into the well from the ground, and extracting the residual coal
bed gas in the goafs. According to the method, the mode of drilling the well from the ground and penetrating through the residual coal pillars is adopted. The method has the advantages of low construction difficulty and low accident occurrence rate.