Numerical Simulation of Gas Pre-drainage from Mining Area by Parallel Holes Drilled along Coal Seam

In order to obtain the gas drainage effect by both long and short staggered parallel boreholes along the coal seam,a mathematical model for gas drainage by parallel boreholes drilled along the coal seam was established and the finite volume method was applied to simulate the gas pressure distribution in coal body around the borehole and the accumulative gas drainage quantity per borehole at different time. The simulated results showed that the reasonable arrangement of both long and short staggered boreholes along the seam achieved good drainage effect; the gas drainage effect by the boreholes along the seam was closely related to the gas permeability and the original gas pressure of the coal seam and the borehole arrangement in the coal seam.