Study on Gas Drainage Technology of Throughput Fracturing Permeability Improvement by Borehole in Underground Mine

In order to obviously enlarge the cofficient of the seam permeability and reach a target of the high efficient gas drainage, a gas drainage technology of t hroughput fracturing permeability improvement by borehole in underground mine was provided. It was found that during the operation of the throughput fracturing, radial guided fracturing, peripheral guided fracturing, shearing fracturing, turning fracturing and others occurred on the max and min horizontal main stress directions. The gas migration channel with a high speed was formed under the displacement support compatibilization of the borehole surface wall. The site experiments showed that after t he throughput fracturing conducted, in comparison with no measure conducted, the pure quantity of gas drainaged from a single borehole increased by 7 ~ 12 times, th e volume fraction of gas drainaged increased by 4 ~ 5 times, and the attenuation coefficient of the borehole gas flow reduced by 1 14~ 1 /3. In comparison with the con ventional hydraulic fracturing, the pure quantity of gas drainaged increased by 1. 6 ~ 3. 0 times, the volume fraction of gas drainaged increased by 1.2~ 2. 0 times, an d the attenuation coefficient of the borehole gas flow reduced by 1 /5~ 1 /3.