Accurate time-delay presplitting blasting reinforcement coal seam gas extraction method

Abstract

The invention discloses an accurate time-delay presplitting blasting reinforcement coal seam gas extraction method. By use of an accurate time-delay presplitting blasting technology, a blast hole detonation sequence is reasonably arranged, a reasonable time-delay interval of an electronic detonator is adjusted, the master oscillator frequency of explosion seismic waves is enabled to be similar to or the same as the inherent frequency of a coal seam, and as a result, a coal body quite far away from a blast hole and a coal body nearby the blast hole generate resonance together. Due to the resonance effect of coal bodies around the blast hole, the coal body quite far away from the blast hole and the coal body medium nearby the blast hole are subjected to effects of stress, shearing forces and compression stress which are alternatively changed, size fluctuation of apertures and cracks in a coal matrix is caused, a new crack network is generated in the coal body quite far away from the blast hole, the crack growth degree of the coal body nearby the blast hole is further improved, the crack expansion scope and the expansion degree of the coal body nearby the blast hole are increased, the influence scope and the influence degree of presplitting blasting antireflection are enlarged, and accordingly, the scope and the amplitude of increase of coal seam permeability are further improved.

Description

technical field [0001] The invention relates to a method for intensified extraction of coal seam gas based on precise time-delayed pre-splitting blasting and drilling in a working face, and belongs to a method for intensified extraction of coal seam gas. Background technique [0002] Pre-extraction of coal seam gas is one of the effective methods for the prevention and control of mine gas dynamic disasters, the development of coal bed methane and the reduction of methane greenhouse gas emissions in mining areas. and utilization, and ensure the safety of coal mining. In some high-permeability coal seam mines abroad, this technology has achieved good application results. However, most of the coal seams in my country are low-permeability coal seams (35% of which have a permeability lower than 0.1mD, 37% of which have a permeability of 0.1-1.0mD, 28% of which are greater than 1.0mD, and fewer coal seams greater than 10mD). The coal seam gas extraction rate is low, which serious...

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Problems solved by technology

[0003] However, from the perspective of the energy sources produced by pre-splitting blasting, the energy of blasting shock waves and stress waves accounts for about 10-15% of the total energy, and the energy of seismic waves accounts for about 20%. Most of the energy that is extremely difficult to be used is consumed in the medium. Plastic flow, excessive crushing and heat loss

The existing pre-splitting blasting technology only considers the generation, expansion and penetration of coal seam cracks near the blasthole (about 150 times the radius of the blasthole) by the blasting shock wave, stress wave and blasting gas. Seismic waves with 20% of the total energy have not been fully utilized, which makes the scope and degree of impact of pre-splitting blasting coal seam anti-reflection relatively small, which limits the development and application of pre-splitting blasting coal seam anti-reflection technology

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