Comprehensive three-dimensional gas drainage mode based on directional drilling technology

Applications of directional drilling technology in extracting solid coal by bedding borehole, extracting goaf by high borehole, extracting pre-excavated area crossing fractured zone and so on were analyzed by taking Chengzhuang Coal Mine as an example. A comprehensive three-dimensional gas drainage mode based on directional drilling technology was researched. Bedding progressive modular drainage technology is applied to solid coal-seam, which can realize benign replacement of mining quantity and drainage quantity through long-time and large-scale drainage and cyclic progress among pre-drainage model, tunneling face and mining face. Roof high directional borehole drainage technology is applied to gas accumulation region at upper corner under U type ventilation. High directional boreholes and upper corner form a connection system through fractured zone, and gas in goaf is extracted by the borehole through fracture, so as to decrease gas concentration in goaf. Comb-like directional borehole technology in coal-rock-coal type roof is applied to fractured coal-seam. Main boreholes are arranged in roof. Comb-like branch boreholes are constructed and enter coal-seam after the main boreholes cross fractured coal body, so as to protect next roadway tunneling. Combined comb-like directional borehole technology of gas drainage on top and water drainage at bottom is applied to coal-seam watering. Water drainage boreholes in coal-seam and gas drainage boreholes in roof can realize connection of gas-water flow field in space, and water-drainage pressure-decrease by the boreholes in coal-seam is good for gas drainage by the boreholes in roof. Gas drainage rate of Chengzhuang Coal Mine achieves 60% by use of the gas drainage mode.