Theoretical Basis and Technical Method of Permeability Enhancement of Tectonic Coal Seam by High Intensity Acoustic Wave In Situ

Abstract

Tectonic coal seams are characterized by soft, low permeability and high gas outburst. The traditional gas control method is the intensive drilling and extraction in this seam, which is not only large in engineering quantity, high in cost, difficult to form holes and low in extraction efficiency, but also easy to induce coal and gas outburst, which is a difficult problem for global coal mine gas control. To solve this difficult problem, the controllable shockwave equipment developed by the author’s team and successfully applied in the practice of permeability enhancement of coal seam, combined with the principles of shock vibration sound wave generation and shock wave attenuation and evolution in the rock stratum, a new idea of loading a controllable shock wave in the roof and floor of coal seam is proposed. The shock wave first attenuates and evolves into a high-strength sound wave in the roof and floor rock stratum, and then enters and loads into the coal seam to achieve the purpose of increasing permeability without damaging the physical properties of the tectonic coal seam and facilitating the opening of the original fractures. According to the new technical ideas, the implementation scheme and key parameters of the gas pre-extraction models in tectonic coal seam are designed, including the penetration drilling, roof and floor horizontal holes, shield tunneling and the high-strength acoustic wave of the working face, which provides a new technical approach to solve the problem of high efficiency and low cost gas extraction in the tectonic coal seam.