Upstream-blocking and downstream-seepage method for extracting gas in mining area

Abstract

The invention discloses an upstream-blocking and downstream-seepage method for extracting gas in a mining area. The upstream-blocking and downstream-seepage method comprises the following steps of respectively drilling to a position which is 20-30m downward away from a fourth system interface, a position which is 5-6m upward away from a top plate of a seventh coal bed, a position which is 7-8m upward away from a top plate of a tenth coal bed and a position which is 3-5m downward away from a base plate of the tenth coal bed by using drill bits with different sizes and drilling to form a first drilling hole (1), a second drilling hole (5), a third drilling hole (7) and a fourth drilling hole (10); respectively driving a first casing pipe (2), a second casing pipe (6), a third casing pipe (8) and a cork (11); forming through holes (9) in the lower part of the third casing pipe (8), mounting expanding rubber between the second casing pipe and the third casing pipe and closing, then cleaning a well and extracting the gas. According to the upstream-blocking and downstream-seepage method disclosed by the invention, the problem that gas extraction is influenced due to the fact that a mining well seeps water can be effectively solved, the gas in the coal beds is released to the maximum extent and the extracting rate of the gas is increased; meanwhile, predominant threat of the seventh coal bed, the eighth coal bed and the ninth coal bed can be eliminated, the gas emission quantity of a mining face is reduced and the safety of mine production is ensured.

Description

technical field [0001] The invention relates to a gas drainage method for surface drilling, in particular to a method for gas drainage in a mining area by upper plugging and lower seepage of surface drilling, and belongs to the technical field of gas drainage. Background technique [0002] Coal seams in most mining areas in my country are characterized by softness, low gas permeability, high gas content, and high pressure. Gas drainage is difficult, which seriously affects mine safety production. The wells in the surface mining area take advantage of the favorable opportunity of pressure relief in the upper coal seam caused by the mining of the coal mining face in the lower coal seam, and extract the gas accumulated in the goaf of the working face in the lower coal seam and the decomposed gas in the upper coal seam for pressure relief. However, due to the influence of rock movement and ground subsidence caused by the mining of the working face, the drilling deformation and d...

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Problems solved by technology

[0003] Aiming at the problems existing in the above-mentioned prior art, the present invention provides a method for gas extraction in the mining area with the upper blockage and the lower seepage. Thi

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