A method for high-gas coal seam working surface drilling and exploitation gas pre-drainage

Abstract

The invention provides a method for high-gas coal seam working surface drilling and exploitation gas pre-drainage and belongs to coal seam drilling and exploitation gas pre-drainage methods. An ultra-thin coal seam is first drilled and exploited for pressure relief and permeability enhancement in coal seams; spiral drilling machines are arranged on a headentry and a tailentry of a first mining working surface to drill and exploit the current working surface and the next working surface; drilling and exploitation excavation makes rock strata around drilling and exploitation holes get loose and causes fracture development; under the protection of casing pipes, with drainage pipes, gaps between the drilling and exploitation holes and the drainage pipes are filled with high water content filling materials, so that drilling and exploitation and drainage concentric holes are formed; after the arrangement of all concentric holes of the headentry and the tailentry of the working surface is complete, drilling and exploitation gas pre-drainage can be carried out. Drilling and exploiting the ultrathin coal seam causes stress concentration around openings of the drilling and exploitation holes and plastic deformation of surrounding rocks, so that fracture development is caused and the adsorption capacity of coal seam gas decreases; through theoretical calculation, it is obtained that the gas dilution effective radius is 5 times the radius of the drilling and exploitation holes. The mining method for first mining high-gas coal seams is reliable, is simple in process, and guarantees the safe mining of first-mining high-gas coal seams.

Description

technical field [0001] The invention relates to a method for pre-extracting gas in coal seam drilling, in particular to a method for pre-extracting gas in high-gas coal seam working face. Background technique [0002] After years of high-intensity mining, shallow coal resources have been gradually exhausted, and coal mining has entered deep areas, especially in the relatively developed central and eastern mining areas. The main mines have developed to the middle and late stages, and the main mining depth has reached more than 800m, and the partial mining depth has reached 1500m . Due to the large mining depth, the large in-situ stress, gas pressure and content, the possibility of coal and gas outburst, impact mine pressure and other dynamic disaster accidents in mines increases, which has become a key problem that restricts the safe mining of deep coal resources and needs to be solved urgently. However, the use of thin coal seam protection layers with low gas pressure, low ...

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Problems solved by technology

[0003] The purpose of the present invention is to provide a method for pre-extracting gas during drilling and mining of high gas coal seam working face, so as to solve the problem of serious accidents caused by a large amount of gas pouring into the working face of the protective layer in the initial stage of pressure relief in the traditional protective layer mining process

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