Mining-coal bed nearly horizontal gas extraction borehole sealing method

Abstract

A mining-coal bed nearly horizontal gas extraction borehole sealing method is mainly suitable for gas extraction boreholes at sites like coal faces in underground coal mines and coal roadways. The sealing method mainly includes two parts: static sealing and dynamic sealing. For a gas extraction borehole, static sealing is performed firstly and includes two times of grouting: for the first grouting, expansion cement grout is adopted to seal positions outside a fissure zone, and for the second grouting, slurry is adopted to seal positions inside the fissure zone; after a period of time, dynamic sealing is performed and includes that the expansion cement grout and the slurry are constantly grouted into the borehole by utilizing underground compressed air to enable the borehole and surrounding fractures to be always filled with the expansion cement grout and the slurry so as to realize dynamic sealing. By the method, grouting fluid can be enabled to effectively seal space inside the borehole and coal fracture areas surrounding the borehole in real time, and maximization of space and fracture sealing is realized. The mining-coal bed nearly horizontal gas extraction borehole sealing method is simple in structure, convenient to operate, low in cost and evident in effect.

Description

technical field [0001] The invention relates to a method for sealing a near-horizontal gas drainage borehole in the coal seam, which is mainly applicable to gas drainage boreholes in underground coal mining working faces of coal mines, coal uncovering places in Shimen, coal lanes and the like. Background technique [0002] Gas disaster is one of the main natural disasters in coal mines in my country, and has become the main contradiction restricting the safety production of coal mines. Draining coal seam gas through construction boreholes is an important means of controlling gas disasters in coal mines. In coal mine gas drainage work, the sealing quality of boreholes is the key factor of the drainage effect. [0003] Due to the low strength of the coal and rock mass around the borehole in a single high-gassy and low-permeability coal seam near horizontal drainage (especially in soft coal seams), there are often micro-cracks around the borehole, which increases the difficult...

AI Technical Summary

Problems solved by technology

[0003] Due to the low strength of the coal and rock mass around the drilling hole in a single high-gassy and low-permeability coal seam near horizontal drainage (especially in soft coal seams), there are often micro-cracks around the drilling hole, which increases the difficulty of sealing

At present, the sealing methods mainly include: cement mortar sealing and polyurethane sealing. The former is prone to shrinkage after sealing, and the sealing effect is poor; the latter often fails to achieve the ideal sealing state due to insufficient sealing length, and the sealing material has certain toxicity. And the price is high, resulting in high sealing cost, which is difficult for coal mines to bear

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