Forward multi-stage large-diameter reaming technology for directional high-level borehole in roof
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摘要: 顶板高位定向钻孔是煤矿井下采动卸压瓦斯治理的重要手段,受钻进装备限制,顶板高位定向钻孔一次成孔直径小,需孔群布置才能达到良好的抽采效果。针对该问题,开发了先施工定向先导孔、再利用钻机回转钻杆带动孔内扩孔钻头对先导孔进行分级增扩的顶板高位定向钻孔正向多级大直径扩孔技术。基于等转矩原理分析确定了扩孔直径级配参数,研制选配了螺旋刀翼型组合式扩孔钻头、高强度高韧性扩孔钻杆、大功率定向钻机、高压大流量泥浆泵车等钻进装备。在山西晋城无烟煤矿业集团有限责任公司寺河矿W1304工作面进行现场试验,结果表明采用正向多级大直径扩孔技术可使顶板高位定向钻孔直径由96 mm增大至153 mm,工作面回采期间回风最大瓦斯体积分数为0.47%,直径153 mm钻孔瓦斯抽采流量为直径96 mm钻孔的近3倍,瓦斯抽采效果显著。Abstract: Directional high-level borehole in roof is an important means to control mining pressure-release gas in coal mine underground. Due to limitation of drilling device, the borehole diameter is small in once-through drilling, and borehole group arrangement is needed to achieve good drainage effect. In order to solve the above problem, a forward multi-stage large-diameter reaming technology for directional high-level borehole in roof was developed, which constructed directional pilot hole firstly and then enlarged the pilot hole level by level though rotating drill pipe in drilling machine driving reaming bit in borehole. Reaming diameter gradation parameters were analyzed and determined on the basis of equal torque principle, and drilling devices were developed and selected including spiral blade and combination reaming bit, reaming drill pipe with high-strength and high-toughness, high-power directional drilling machine, mud pump truck with high-pressure and large-flow, etc. The field test was carried out at W1304 working face of Sihe Mine of Shanxi Jincheng Anthracite Mining Group Co., Ltd. The test results show that the diameter of directional high-level borehole in roof can be increased from 96 mm to 153 mm by use of the forward multi-stage large-diameter reaming technology, the maximum return-air gas volume fraction is 0.47% during the working face mining, and gas drainage flow of 153 mm borehole is nearly three times than that of 96 mm borehole, which verifies 153 mm borehole has salient gas drainage effect.
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