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Gas drainage for the single and low gas permeability coal seam is the key technical problem hampering efficient coal mine gas drainage and without which mining safely cannot be realised in China. To solve this problem, this paper presents an engineering method for enhanced coalbed methane recovery based on high-pressure hydraulic flush from floor tunnels. The first step is to evaluate when the likelihood of coal and gas outburst reaches dangerous levels according to coal seam parameters (including coal seam gas contents, gas pressure, permeability and geological conditions). With these parameters in place, the second step is to determine and optimise borehole parameters, such as the effective influencing radius of hydraulic flush, hydraulic flush space between drills and borehole number to make sure that the coal seam stress is fully released and permeability is dramatically increased. What is also included in this step is the employment of a high-pressure hydraulic flush of coal from boreholes drilled fr...

Methods based on flow measurement and pressure measurement were employed in this paper to determine pressure relief scope of gas drainage boreholes for coal and gas outburst prevention and control. In order to measure the extent of pressure relief, the principle to choose proper sites was set up based on general gas geology features. The data acquired from underground testing showed that the risk of coal and gas outbursts has been eliminated in the scope of pressure relief. The exclusive method developed in the research could be utilized as the guidance for the future optimization of parameters for hydraulic flushing borehole arrangement