Research on directional hydraulic fracturing technology with guiding channel for permeability increasing in Chahasu Coal Mine
In view of the low permeability of coal seam and the difficulty of gas drainage in Chahasu Coal Mine,directional hydraulic fracturing technology with preset guiding channel was proposed to improve the efficiency of coal seam gas drainage.The hydraulic fracturing gas drainage coupling model of coal rock stress-damage-permeability was established by COMSOL Mutiphysics simulation software,the changes of elastic damage modulus and effective gas drainage radius of coal seam under the action of guiding channel were analyzed,and field tests were carried out at 24130 working face.The numerical simulation and field test results show that the horizontal principal pressure of coal seam under the action of guiding channel is greater than the vertical principal stress,showing the rock strata tensile fracture first in the horizontal direction.The average gas concentration of the drainage borehole after the field directional hydraulic fracturing operation is 42.4%,the average gas pure content is 0.009 8 m3/min,and the effective extraction radius is 3.6 m,which are roughly consistent with the numerical simulation results.
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