Coal seam fracturing by a high-pressure waterjet technique to increase efficiency of coal mine gas drainage

Abstract

In an effort to eliminate the hazard posed by coal seam gas and increase the efficiency of coal seam gas drainage in an underground coal mine, a high-pressure waterjet fracturing technique has been developed, optimized experimentally and numerically, and trialled underground. Numerical and laboratory results indicate that the slotting capacity of the high-pressure waterjet fracturing system can be improved by optimizing the geometrical structure and parameters of the nozzle. The results from field investigation showed that the gas production rate can be more than doubled by using the high-pressure waterjet-assisted method before and during longwall extraction.