Study on 3D gas drainage technology of high cutting coal mining face in deep and high gassy mine

In order to effectively improve the gas drainage efficiency, taking the gas (oil bed gas) drainage in Huangling Mine as a target, a site investigation, numerical calculation and site monitoring as well as other methods were applied to comprehensively analyze the gas inflow path of a deep high gassy mine. A comprehensive 3D gas drainage technology was implemented. The study showed that four sandstone gas reservoirs in the coal mining face were all affected by the mining and were individually within the subsidence zone, collapsed zone and cracking zone as well as bottom disturbance scope. Those reservoirs would provide the gas disaster sources to the goaf and coal mining face. According to the rock strata structure and mining influences, the whole gas drainage could be divided into a goaf, mining zone and non mined seam. A dynamic comprehensive 3D gas drainage technology was established. A site survey was conducted on the gas - oil strata content at each location. The evaluation results showed that the comprehensive gas drainage technology of the coal mining face could realize a space fully covered gas drainage. The gas drainage volume of each location could be increased and the gas concentration would be decreased. The gas volume fraction in the surrounding rock and the goaf was reduced by 40%, 68% and 41%.The comprehensive gas drainage technology could improve the mine gas drainage rate and could provide a powerful support to the mine gas control.