Hole drilling and protecting method of drilling tool for soft coal seam gas extraction hole drilling and protecting

Abstract

A hole drilling and protecting method of a drilling tool for soft coal seam gas extraction hole drilling and protecting comprises the following steps that the drilling tool for soft coal seam gas extraction hole drilling and protecting is installed in a drilling position of a coal seam roadway; the front portion of a drill bit is stressed so that a compression spring in the drill bit is compressed, a telescopic column is made to slide outwards, after the preset stroke is reached, the drilling diameter of a hollow internal slag discharging variable-diameter drill bit is increased and kept at as a definite value finally, and a PVC hole protecting pipe follows up gradually. Water flow reaches the bottom of a drill hole through a gap between the PVC hole protecting pipe and a hollow unthreaded drill rod, or high-pressure air penetrates through the hollow unthreaded drill rod and reaches the bottom of the drill hole. When the stress at the front end of the drill bit disappears, the telescopic column resets to the initial position, the hollow internal slag discharging variable-diameter drill bit and the hollow unthreaded drill rod can be drawn out at the moment, the PVC hole protecting hole is reserved in the hole, and gas is exhausted smoothly. By the adoption of the hole drilling and protecting method, the speed of gas extraction hole construction is improved, construction safety is guaranteed, and innovation of the drilling tool for soft coal seam gas extraction hole drilling and protecting is achieved.

Description

technical field [0001] The invention belongs to the technical field of drilling construction for gas drainage in coal mines, and in particular relates to a method for drilling and protecting holes with a drilling tool for drilling and protecting holes for gas drainage in soft coal seams. Background technique [0002] Gas has always been an important issue affecting the safety of coal mine production. At present, the main prevention and control measures are to lower the screen pipe after drilling to extract gas. Most of the coal seams in our country are soft coal seams. When ordinary drill bits are used for drilling construction, due to the poor porosity of the soft coal seam, the hole wall is extremely unstable, and the drill hole collapses easily, causing the drill bit to be unable to be taken out. safety hazard. Even if it can be successfully removed, it will affect the subsequent release of the screen pipe, which will not only delay production, but also cause unnecessary...

AI Technical Summary

Problems solved by technology

Most of the coal seams in our country are soft coal seams. When ordinary drill bits are used for drilling construction, due to the poor porosity of the soft coal seam, the hole wall is extremely unstable, and the drill hole collapses easily, causing the drill bit to be unable to be taken out. safety hazard

Even if it can be successfully removed, it will affect the subsequent release of the screen, which will not only delay production, but also cause unnecessary economic losses

Chinese patent (patent number: CN 202596582 U) discloses a variable-diameter drill bit, which can realize the function of back drilling and reaming, effectively preventing the phenomenon of drill sticking, but after using this drill bit for construction, it is still necessary to back the drill and lower the screen tube, it will inevitably cause the screen tube to be unable to be lowered or the lowering depth is not ideal

Another Chinese patent (patent number: CN 102877791 A) discloses a drill bit and a drilling device. The movable drill core is straddled on the drill bit body, and the casing can pass through the axial through hole of the drill body. Its own gravity opens the movable drill core at one end of the main body of the drill bit, so as to realize casing running inside the drill bit, avoiding various disadvantages of casing running after withdrawing the drill bit, but due to the limited space in the drill hole, the diameter of the lower casing is relatively small. Affect gas extraction efficiency

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