Study on Effective Drainage Radius of Advance Borehole Based on Gas Flow Theory

In order to accurately measure the effective drainage radius of the advance borehole, from the view of the seam gas flow law, the influence factors of the gas drainage boreholes were discussed.In a certain seam, due to the restriction by the conditions, the gas drainage effect improved by the variation of the borehole dia meter and length, seam permeability coefficient and others was limited. According to the relationship between the gas emission value and drainage time of a borehole, b ased on the site practices in Xinji No.1 Mine, with the calculation on the variation rate of the gas emission in a borehole, an effective drainage radius of the advance bor ehole was accurately determined and the effective drainage radius of advance borehole with 091 mm in No.13-1 seam was 0.8 m.