Gas-liquid two-phase alternating phase drive fracturing coal body enhanced gas drainage method in underground coal mine

Abstract

A method for enhanced gas extraction by coal mine underground gas-liquid dual-phase alternating phase-driven fracturing of a coal body. Constructed in a present coal seam or a permeable stratum are a fracturing borehole and a water guiding hole, where both boreholes are sealed to withstand high pressures. Fracturing equipment is connected, pressurized water of no more than 3 MPa is injected into the fracturing borehole, and, a water pump is shut off after 10 minutes of hydraulic fracturing of the fracturing borehole, thus stopping the hydraulic fracturing. An air pressure booster is turned on for gas-phase fracturing of the fracturing borehole, and, when the pressure reaches 3 MPa, the air pressure booster is turned off, thus stopping the gas-phase fracturing. This is repeated for multiple times, when water flows out of the water guiding hole distanced from a side of the fracturing borehole, the hydraulic fracturing is stopped, while the gas-phase fracturing is continued, and, when water ceases to flow out of the water guiding hole or when a gas erupts therefrom, the gas-phase fracturing is stopped. A fuel gas extraction pipe network is connected to the fracturing borehole and the water guiding hole for fuel gas extraction. The method effectively solves the problem of fuel gas release and analysis being impeded by residual water when only hydraulic fracturing is used, thus allowing cracks within a coal body to be fully developed to an improved degree, and enhancing coal seam air permeability and fuel gas extraction effects.

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

Images