松软薄煤层条带消突下斜定向钻孔成孔护孔技术研究与应用

Downward directional drilling and hole protection technology for coal roadways strip outburst prevention in soft thin coal seams

针对松软薄煤层煤巷条带消突长距离下斜钻孔,存在成孔难、易钻遇煤层顶底板、积水堵塞瓦斯抽采通道的难题,提出了氮气排渣下斜定向钻进成孔与护孔技术,采用高压氮气排渣、大功率气动螺杆钻具定向、“波浪式”轨迹控制和三层管护孔排水技术,在河南省平煤股份一矿开展现场试验,完成8个孔深超300 m下斜定向长钻孔,煤层钻遇率90%以上,全孔段下三层护排水管,平均下入深度302 m,支管平均抽采纯量1.66 m^(3)/min,平均瓦斯浓度17.5%。试验结果表明:该技术可有效解决松软薄煤层下斜钻孔长距离定向成孔、全孔段筛管护孔和排水的技术难题,提高了钻孔成孔深度和煤层钻遇率,实现了下斜孔全孔段护孔和排水,保障了瓦斯抽采效果,为松软薄煤层煤巷条带长距离消突提供技术保障,在类似地层条件具有广泛的应用推广价值。

In view of the problems of difficult hole formation,easy to drill into the coal seam roof and floor,and water blocking the gas extraction channel,the technology of downward oblique directional drilling and hole protection was proposed,using high-pressure nitrogen slag discharge,high-power pneumatic screw drilling tool orientation,“wave-type”trajectory control and three-layer pipe hole protection and drainage technology,which was tested in Pingmei No.1 Mine,and 8 holes with a depth of more than 300 m were completed,and the coal seam drilling rate was more than 90%.The average depth of the three layers of drainage pipes in the whole hole section was 302 m,the average pure pumping volume of the branch pipe was 1.66 m^(3)/min,and the average gas concentration was 17.5%.The test results show that this technology can effectively solve the technical problems of long-distance directional hole formation and full-hole screen hole protection and drainage in the downwardoblique borehole of the soft and thin coal seam,improve the drilling depth and coal seam drilling rate,realize the hole protection and drainage of the whole hole section of the downward oblique hole,ensure the gas extraction effect,provide technical support for the long-distance outburst elimination of the coal roadway strip in the soft and thin coal seam,and have a wide application range of and promotion value in similar formation conditions.