Physical simulation and drilling optimization design of hydraulic cavitation and permeability enhancement in Wuhushan Coal Mine

Abstract

For the problems that poor gas permeability and strong gas adsorption in the coal seams of Wuhushan Coal Mine leads to poor drilling and extraction efficiency and low extraction rate, physical simulation and on-site testing methods were used to numerically simulate the changes in drilling parameters before and after hydraulic drilling, and then optimize a suitable gas extraction drilling layout for the mine. The results show that under the condition that the 011006 working face of Wuhushan Coal mine is consistent with the production continuity in the mine, the optimal diameter of hydraulic cavitation is 0.5 m and the reasonable layout interval is 4 m; the average volume fraction of gas extraction is 70.4%, which is 3.8 times of the average volume fraction of ordinary borehole and 3.5 times of pure gas extraction; using the hydraulic cavitation optimization parameters and the arrangement of ordinary boreholes can effectively activate the ordinary boreholes at intervals; by comparing the evaluation indexes such as the pressure relief and permeability improvement effect of borehole construction, gas extraction efficiency, disturbed area of coal body, volume and hole formation rate of boreholes, under the same area module, the gas extraction pure quantity of module 2 using the spaced borehole arrangement is 1.8 times that of module 1.

Keywords

• gas drainage
• hydraulic cavitation
• hydraulic punching
• drilling optimization
• coal seam
• process parameters