Method for forcedly draining gas from underground gas and liquid alternate phase-drive fracture coal of coal mine

Abstract

The invention discloses a method for forcedly draining gas from underground gas and liquid alternate phase-drive fracture coal of a coal mine. The method includes constructing a fracture drilled hole and a water guide hole in a local coal seam or across seams and performing high-pressure-resistance sealing on the two drilled holes; connecting fracture equipment with the fracture drilled hole, injecting pressure water under the pressure not higher than 3MPa into the fracture drilled hole, performing hydraulic fracture on the fracture drilled hole for 10 minutes, then shutting off a water pump and stopping hydraulic fracture; starting a gas booster to perform gas-phase fracture on the fracture drilled hole, shutting off the gas booster when the pressure reaches 3MPa and stopping gas-phase fracture; repeating the same procedure by multiple times, stopping hydraulic fracture when water flows out of the water guide hole distanced from one side of the fracture drilled hole, continuing gas-phase fracture and finishing gas-phase fracture when water stops flowing out of the water guide hole or gas flows out; connecting the fracture drilled hole and the water guide hole into a gas drainage pipe network and draining the gas. The method has the advantages that the problem that water remains after single hydraulic fracture and prevents gas from being released and desorbed can be effectively solved, internal fracture of the coal can be developed sufficiently, and the gas permeability of the coal seams and a gas drainage effect can be improved.

Description

technical field [0001] The invention relates to an underground gas-liquid two-phase alternate phase drive fracturing coal body enhanced gas drainage method in coal mines, which belongs to the technical field of gas control in underground areas of coal mines, and is especially suitable for pressure relief and permeability enhancement of high-gas and low-permeability coal seams in underground coal mines. Background technique [0002] my country's coal seam gas has the characteristics of microporosity, low permeability, and high adsorption. More than 80% of coal seams are high gas and low permeability coal seams. The mining of high-gassy and low-permeability coal seams is often accompanied by a large amount of gas emission, especially with the efficient intensification of coal production and the increase of mining depth, the amount of gas emission is increasing, and the threat of gas explosion and gas outburst is increasing. It's getting serious. The main measure to solve the ...

AI Technical Summary

Problems solved by technology

With the promotion of the scope of application, the complex occurrence conditions of coal seams, and the increase of low-permeability coal seams, hydraulic fracturing technology is gradually limited, mainly manifested in the fact that after high-pressure water enters the coal body in the soft coal seam, it is difficult for the water to be affected by the capillary force of the coal body. Discharge, block the channel of gas gushing, weaken the effect of hydraulic fracturing to enhance the permeability of coal and improve the effect of gas drainage

[0004] At present, the research and application of underground gas fracturing in coal mines are more common in high-energy gas fracturing (CO 2 , N 2 etc.), it has achieved certain effects on coal permeability enhancement, but the preparation, transportation and fracturing control of high-energy gas are difficult, which hinders the promotion of high-energy gas fracturing

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