Method for gas extraction by coal seam roof weakening through L-shaped drilling staged fracturing

Abstract

The invention relates to a gas extraction method for L-shaped borehole staged fracturing of a weakened coal seam roof, which comprises the following steps: 1) selecting the drilling position and parameters at the ground position corresponding to the working face of the coal seam to be mined, and constructing L 2) After the construction of the L-shaped borehole is completed, casings and fracturing equipment are arranged in the L-shaped borehole, and each preset fracturing site of the coal seam roof is fractured by means of hydraulic jet staged fracturing, to weaken the roof of the coal seam; 3) After the fracturing operation is completed, remove the fracturing equipment and connect the casing in the L-shaped borehole to the gas drainage device; 4) Start the coal mining operation at the coal mining face, and While the coal face is moving forward, the gas in the fracture zone is extracted through the gas extraction device. This solution solves the problems in the prior art that the amount of gas extraction is limited and the extraction intensity is not enough, and the coal seam gas cannot be extracted and utilized to a great extent.

Description

Technical field [0001] The invention relates to the field of gas drainage, in particular to an L-shaped borehole segmented fracturing method for weakening the coal roof. Background technique [0002] my country is the world's largest coal producer and consumer, as well as the country with the most serious gas disasters. Gas disasters severely restrict the safe production of coal mines in our country. In my country, 94% of coal is mined through underground mining methods. However, with the continuous increase of underground mining depth and production capacity, coal seam gas content and pressure continue to increase, roof management becomes increasingly difficult, and underground working faces are dangerous. Also getting higher. [0003] In response to this increasingly severe and deep-seated mining problem, my country has formed a series of roof management methods, gas drainage methods, and drilling methods centered on coal pillar support, blasting, water injection softening, and h...

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Problems solved by technology

[0004] The purpose of the present invention is to provide a gas extraction method for L-shaped borehole segmental fracturing and weakening of the coal seam roof, which can solve the problem of limited gas extraction volume and insufficient extraction strength in the prior art, which cannot achieve the ultimate goal of coal seam gas. Problems that are exploited to a large extent

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