Dynamic response of coal seam parameters during gas drainage and its application

The parallel borehole drainage experiments with different borehole amounts were conducted based on the self-developed multi-field coupling test system for coal-bed methane (CBM) drainage. The different parameters during gas drainage showed the similar evolution which dropped quickly at first and then leveled off. It can be concluded that increasing boreholes amount can improve the drainage efficiency and reduce drainage time effectively. The visualizations of gas pressure cloud maps,isobaric surfaces and slice maps were realized by MATLAB software. During gas drainage,the gas pressure dropping zone expanded outward with the shape of ellipsoid and the borehole direction was the long axis direction. At the same time,the dynamic evolution of outburst elimination zone was plotted based on gas pressure. The outburst elimination zones propagated outward in multiple approximate circles with the multiple boreholes as their respective centers. However,the multiple outburst elimination zones gradually merged together and formed a new outburst elimination zone to realize outburst elimination of the coal seam. The research results provide a reference for the realization of gas drainage data visualization and gas precise drainage.