Method for extracting gas from high gas low permeability coal seam by punching, slotting, pressure releasing, and permeability increasing

Abstract

The invention discloses a method for extracting gas from high gas low permeability coal seam by punching, slotting, pressure releasing and permeability increasing, comprising the following steps: whena drill is drilled into a predetermined position of the coal seam, coal bodies at both sides of a drill hole are cut in the drill hole by high pressure water jet with a certain pressure and flow; a flat slot is formed at both sides of the drill hole; the cut coal bodies is led out the hole by the high pressure water jet. The exposed area of the coal body at the slotted part in the drill hole aregreatly increased, namely that an extremely thin protective layer is exploited with local scope of the flat slot, which enlarges effective influential range of pressure releasing, permeability increasing and gas discharging of the coal bodies in the drill hole, thus the air permeability of the coal bodies is increased about 200-300 times, the average amount of single-hole gas extraction reaches 0.3m<3>/min, the concentration of the gas extraction is 30-60%, gas drainage rate of working face of coal extraction is more than 50%, the number of drill holes for gas drainage is reduced by 10-20% after slotting, pressure releasing and permeability increasing. The method realizes the safety, high efficiency and uniform extraction of the gas from the high gas low permeability outburst coal seam, and changes high gas coal seam with outburst danger into low gas coal seam without outburst danger.

Description

technical field [0001] The invention relates to a gas drainage method for punching and slotting seams with high gas and low permeability to relieve pressure and enhance permeability, and is especially suitable for regional gas drainage of high gas and low permeability coal seams. technical background [0002] 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. Gas disasters have become the most important factor restricting the development of efficient and intensive mining technology and safe production. Therefore, how to effectively solve the problem of gas gushing in the process of mining high-gas coal seams is of great significance to the safe production of coal mines. Since the 1970s, my country has carried ou...

AI Technical Summary

Problems solved by technology

These methods all have the problems of small effective impact range of drilling, large drilling construction workload in the working face, and low drainage efficiency. It is necessary to adopt the method of pressure relief and anti-reflection enhancement to expand the effective impact range of drilling and improve the gas drainage effect of the coal seam.