Coal mine underground multistage combustion shock wave-fractured coal body reinforced gas extraction method

Abstract

The invention discloses a coal mine underground multistage combustion shock wave-fractured coal body reinforced gas extraction method. According to the invention, a large amount of N2 or CO2 are injected into a drilled hole through a high-pressure gas cylinder and a pressure reducing valve by means of a gas injection and extraction pipe, and then a certain amount of methane and dry air are injected into a high-temperature high-pressure combustion chamber through the high-pressure gas cylinder and the pressure reducing valve. In this way, the above materials are mixed up and combusted to form ahigh-temperature high-pressure shock wave. When the pressure in the high-temperature high-pressure combustion chamber reaches 30 MPa, an electromagnetic valve is automatically opened. In this way, the high-temperature high-pressure shock wave is instantly released, and the N2 or CO2 is compressed through pushing a piston. As a result, a large amount of cracks are generated on the coal body aroundthe drilled hole. Shock waves are repeatedly generated to form the multi-stage impact, and the impact of a last stage is impacted on the basis of a previous stage. As a result, the cracks of the coalbody around the drilled hole are further expanded and communicated. After the compression of the N2 or CO2 under the multi-stage impact effect, the coal body around the drilled hole can form more fracture networks. Meanwhile, the waste heat of the high-temperature high-pressure shock wave can promote the coal body to be desorbed, so that a certain gas displacement effect is achieved. Furthermore,the high-efficiency gas extraction of the drilled hole is enhanced.

Description

technical field [0001] The invention relates to coal body fracturing and gas drainage, in particular to a coal mine underground multi-stage combustion shock wave cracking coal body enhanced gas drainage method. Background technique [0002] With the increase of energy demand and the increase of mining intensity, the depth of coal mining gradually increases, and the deep coal seam has the characteristics of high geostress, high gas pressure, high gas content and low permeability. Mine disasters occur frequently. Coalbed methane is one of the main factors causing dynamic disasters in deep mines. The global reserves of coalbed methane are about 250 trillion cubic meters, and coalbed methane is not only an efficient and clean energy source but also a greenhouse gas. The greenhouse effect it produces is about It is 25 to 30 times that of carbon dioxide, and coalbed methane has the danger of explosion and outburst. In order to improve energy utilization and reduce mine disasters...

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Problems solved by technology

[0004] Aiming at the problems existing in the prior art, such as limited range of influence of borehole drainage, low degree of pressure relief, small borehole flow rate, large attenuation coefficient, high risk, complicated operation, etc., the present invention provides a high-safety, low-cost A low-cost and easy-to-operate coal mine multi-stage combustion shock wave fracturing coal mass enhanced gas drainage method

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