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Using horizontal directional drilling and liquid nitrogen cyclic freeze-thaw process to improve permeability in gas drainage
Using horizontal directional drilling and liquid nitrogen cyclic freeze-thaw process to improve permeability in gas drainage
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机译:利用水平定向钻井和液氮循环冻融工艺提高瓦斯抽采渗透率
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摘要
A liquid nitrogen cyclic freeze-thaw permeability-improvement gas drainage method based on horizontal directional boreholes comprises: first constructing a main borehole at an intake roadway or a return roadway, a low-level roadway and a high-level roadway, after a drill bit reaches a pre-set target position of a coal bed, uniformly and directionally constructing a plurality of branch boreholes along a horizontal direction of the coal bed, injecting water to the coal bed, opening a valve, filling the main boreholes with liquid nitrogen, rapidly freezing the water injected into the branch boreholes and the periphery of the coal bed, and stopping injecting the nitrogen when an average temperature of a pre-permeability-improvement area monitored by a temperature measuring hole is lowered to −2° C. or lower.
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