Optimization of borehole layout parameters based on fracturing technology of liquid CO₂ phase

In order to achieve the purposes of economical-effectively eliminating coal and gas outburst in low permeability coal seam areas through fracturing technology of liquid CO₂ phase, the paper carried out through-layer gas pre-drainage test using fracturing technology of liquid CO₂ phase in Pingdingshan No.13 mine, on the basis of study of the fracturing radius of influence, through numerical simulation and field verification, the borehole layout parameters for fracturing technology of liquid CO₂ phase were studied. Through simulation and test with different layout and spacing of boreholes, the results showed that first fractur borehole provided the free surface for the the latter fractured borehole so as to make the fracturing developed towards the direction of the free surface, when regional fracturing was taken, it was easy to reduce the unfavorable influence of the free surface through using quincunx layout of the low linearity, the best borehole spacing was 0.5 to 0.6 times the effective influencing radius of fracturing.