保护层开采卸压瓦斯抽采定向钻孔施工关键技术

为了解决下峪口煤矿上保护层开采过程中工作面瓦斯超限问题，提出了煤矿井下卸压瓦斯抽采定向钻进技术方法，分析了装备机具选型、钻孔设计方法、钻孔轨迹调控，研究了大角度开孔、稳压注浆固管、混合钻进、地层判别、快速回转穿异常区和预留分支点六个定向钻孔施工关键技术。工程试验结果表明：该技术具有开孔成功率高、能快速穿过破碎岩层塌孔区域、判别地层准确、钻进效率高、轨迹可灵活调整以及减少施工盲区等优势。定向钻孔的瓦斯抽采浓度平均为35.7%，解决了常规钻孔抽采效果差的问题，提高了保护煤层卸压逸散出的游离瓦斯抽采利用率，为实现卸压开采抽采瓦斯、煤与瓦斯共采的科学构想提供了技术支撑。

Key Technology of Directional Drilling Construction for Gas Extraction and Pressure Relief in Protective Layer Mining

In order to solve the problem of gas overshoot in the working face during the mining of the upper protective layer of a coal mine in northwest China, the directional drilling technique of gas extraction with downhole pressure relief was put forward. Introduces the selection of equipment and tools, the design method of drilling hole and the control of drilling track, and studies six key technologies of directional drilling construction, such as large angle hole opening, stable grouting solid pipe, mixed drilling, formation discrimination, rapid revolving through abnormal area and reserved branch point. The engineering test results show that the technology has advantages such as high success rate of hole opening, fast penetration through the hole area of broken rock, accurate formation identification, high drilling efficiency, flexible trajectory adjustmssent and reducing construction blind area. The gas extraction concentration of directional drilling is 35.7% on average, which solves the problem of poor extraction effect of conventional drilling, improves the utilization ratio of free gas extraction from the coal seam under pressure relief, and provides technical support for the scientific conception of gas extraction, coal and gas joint extraction in pressure relief mining.