Drilling tools for gas drainage in soft coal seams

Abstract

A hole-protecting drilling tool for soft seam gas extraction drilling comprises a support, a power driving device, a guiding supporting frame, a hollow internal slagging diameter-variable drill bit, a hollow glaze drilling rod, a PVC hole-protecting pipe, a first buffer box, a second buffer box, a water supply device, an air supply device and a slag collecting container. According to the hole-protecting drilling tool for soft seam gas extraction drilling, in the drilling process, the front portion of a drill bit is stressed, and therefore an internal compression spring is jacked, so that a retractable column slides outwards; after the retractable column reaches a preset journey, the drilling diameter of the hollow internal slagging diameter-variable drill bit is larger and finally keeps a constant value, and the PVC hole-protecting pipe gradually follows up; and when stress of the front end of the drill bit disappears, the retractable column restores to the initial position, at this moment, the hollow internal slagging diameter-variable drill bit and the hollow glaze drilling rod can be drawn out, and the PVC hole-protecting pipe is left in a hole to enable gas to be smoothly discharged. According to the hole-protecting drilling tool for soft seam gas extraction drilling, the construction speed of the gas extraction hole is increased, construction safety is ensured, and the hole-protecting drilling tool for soft seam gas extraction drilling is innovation of an existing hole-protecting drilling tool for soft seam gas extraction drilling.

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 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 economic losses. Chinese patent (patent number...

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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