Methane drainage optimization by roof-borehole based on physical simulation

As a kind of global disaster, the methane hazards extensively exist in the major coal-production countries. At present, conventional techniques, such as ventilation or drilling bore in coal seam, fail to completely solve the methane problem. To improve the methane drainage efficiency, a new method called roof-borehole, instead of traditional drainage methods (laying pipes in goaf and drilling hole in coal seam), was used to manage the gas disaster in goaf. Therefore, this study used the physical simulation experiment to study and determine the distribution characteristics of the fissure zone and methane zone in the overlying strata of coal seam and the necessary parameters of roof-borehole in turn. In addition, according to the experiment results, the optimal parameters for the position of roof-borehole (vertical distance and horizontal distance) were designed. By testing the effects of different drainage methods in field, it was found that the efficiency of methane drainage was significantly improved by the roof-borehole.