Research and application of hydraulic punching anti-reflection technology in soft coal seam
Zhao Wenwu 1, Wang Yunlong 2, Li Yaolong 1
1. School of Mining and Surveying Engineering, Hebei University of Engineering, Handan 056038; 2. Department of Environmental and Chemical Engineering, Hebei Polytechnic University, Shijiazhuang 050091, China
Abstract：Aiming at the problem of low permeability and difficult gas control in high gas and soft coal seam, taking No.4 coal seam in Huainan mining area as the engineering background, based on the mechanism of hydraulic punching and pressure relief technology, the effect of pressure relief and permeability improvement after hydraulic punching is investigated by means of theoretical analysis and field test, by comparing and analyzing the extraction concentration, single hole extraction amount, gas pressure, gas content before and after punching, as well as the initial velocity of gas emission and drilling cuttings after punching. The results show that after the implementation of hydraulic punching measures in the outburst coal seam, the dynamic stress around the coal body is unbalanced, a large amount of adsorbed gas is converted into free gas, and the gas extraction concentration of the borehole is improved. After punching, the residual gas pressure of the coal seam is reduced from 2.5 MPa to 0.17 MPa, and the residual gas content is reduced from 8.49 m3/t to 2.05 m3/t, which effectively reduces the risk of coal and gas outburst.
