老厂矿区高位定向长钻孔“以孔代巷”瓦斯抽采技术研究

云南老厂矿区无烟煤瓦斯含量高、衰减性强、透气性系数低、瓦斯难于抽采，采用常规顺层钻孔和普通顶板高位钻孔方式难以解决上隅角瓦斯和回风流瓦斯超限问题，而采用顶板高抽巷方式面临工程量大、经济成本高、工期长等问题。通过使用定向大直径钻机施工高位定向长钻孔替代顶板高抽巷的方法，利用FLAC^3D数值差分软件分析煤层顶板断裂带高度。结果表明：老厂矿区8^#煤层垂向18~35 m区域为最佳抽采层位，使用高位定向长钻孔对8^#煤层顶板裂隙抽采后平均抽采瓦斯浓度(甲烷体积分数，下同)可达16%左右，平均抽采瓦斯纯流量为9.05 m³/min，工作面上隅角瓦斯浓度控制在0.60%以下，回风流瓦斯浓度控制在0.40%以下，与采用高抽巷方法的瓦斯抽采效果相当，验证了高位定向长钻孔“以孔代巷”技术的合理性和可行性，可为云南老厂矿区无烟煤瓦斯抽采提供参考。

Research on gas drainage technology by high level directional long drilling to replace drainage gateway in Laochang mining area

The anthracite in Laochang mining area of Yunnan Province has high gas content, high attenuation, low permeability coefficient and difficulty in gas extraction, it is difficult to solve the overlimit problem of gas in upper corner and gas return flow by conventional bedding drilling and ordinary top plate drilling. However, adopting the roof high pumping way faces the problems of large engineering quantity, high economic cost, long construction period and so on.By using the method of directed large diameter long drilling machine construction high directional long drilling to replace the top plate high drainage roadway, the height of the crack band of the top plate of the coal seam is analyzed by using FLAC^3D numerical differential software.The results show that the 18 m to 35 m vertical zone of No.8 coal seam in Laochang mining area is the best extraction horizon, the average gas extraction concentration can reach about 16% after the extraction of the top plate crack of the No.8 coal seam using high-directional long drilling, and the average purity of gas extraction is 9.05 m³/min, the gas concentration in the corner of the working face is controlled below 0.60%, and the gas concentration in the return flow is controlled below 0.40%, which is comparable to the effect of high drainage roadway gas extraction, and verifies the rationality and feasibility of high level long directional drilling to replace drainage gateway, it can provide reference for gas extraction of anthracite in Laochang mining area of Yunnan Province.