Measurement on effective gas drainage radius of boreholes passed through multi seams

In order to solve the problems occurred in the measurement on the effective drainage radius of gas drainage with the boreholes passed through multi seam s in the study area and the completed seam during the mine gas drainage process,related solutions were individually provided. When each seam gas drainage ratio was de termined with the boreholes passed through multi seams for the gas drainage,the product of the seam thickness,in-situ gas content and permeability coefficient was proved as the correlated value of gas drainage and then the correlated value of the gas drainage was calculated with a normalization processing. The main factors affected to the gas drainage value of the boreholes passed through seams were considered. When the effective gas drainage radius of the whole seam was predicted with the study area, a variation of the seam gas coefficient would be occurred and the gas drainage value of the borehole in each seam would be varied. According to the borehole gas drainag e value was propertional to the related drainage correlated value,the borehole gas drainage value of different seam gas parameters was predicted. The results showed that according to the actual conditions of Qinglong Mine ,the effective drainage radius of boreholes passed through seams in the study area and whole seam in No. 16 coal sea m was obtained and could provide the basis to the rational layout of the borehole distance.