Shenyang Research Institute, China Coal Technology and Engineering Group
State Key Laboratory of Coal Mine Safety Technology

针对低透气性高瓦斯煤层预抽瓦斯困难问题,提出导向槽定向水力压裂煤层增透技术,通过理论推导计算煤层段扩孔后塑性区分布,分析穿层钻孔煤层段水压裂缝的起裂与扩展,揭示导向槽定向水力压裂煤层增透的力学机制,研发导向槽定向水力压裂煤层增透装备。在山西中兴煤矿进行现场应用,结果表明:利用水射流方法对穿层钻孔煤层段进行扩孔,使得煤中产生形似圆柱孔洞,穿层钻孔围岩塑性区半径与钻孔半径成正比,钻孔扩孔是增大塑性区范围的一种有效方法,裂隙扩展明显,瓦斯采出率提高。同时研发了一种导向槽定向水力压裂防突成套装备,主要部件有移动高压水力泵站、喷头、喷嘴、螺旋辅助排渣水射流高压钻杆、孔口防喷装置以及高压旋转接头,结合井下水力化作业远程监测和控制,现场监测结果表明,通过增透作业钻孔的方法,平均瓦斯浓度和瓦斯抽采混合量提高到常规孔的2.75倍和1.81倍,说明采取导向槽定向水力压裂措施的增透效果显著。

Aiming at the difficulty of gas pre - extraction in low permeability and high gas coal seam, the technology of directional hydraulic fracturing of coal seam with guide slot was proposed. The distribution of plastic zone after reaming in coal seam was calculated by theoretical derivation, and the initiation and propagation of hydraulic fractures in coal seam of cross-seam drilling were analyzed to reveal the mechanical mechanism of directional hydraulic fracturing of coal seam with guide slot. The permeability- increasing equipment for directional hydraulic fracturing of coal seam with guide slot was developed and applied in Shanxi Zhongxing Coal Mine. The results show that after the water jet reaming of cross-layer borehole in coal seam section, an approximately cylindrical hole is generated in the coal body. The radius of the plastic zone of the surrounding rock of the cross-layer borehole is positively related to the radius of the borehole. Drilling reaming is an effective method to increase the range of the plastic zone, which significantly promotes the development of cracks, and improves the gas extraction effect. A complete set of equipment for directional hydraulic fracturing and outburst prevention of guide slot was developed. The main components are mobile high-pressure hydraulic pumping station, sprayer, nozzle, orifice blowout preventer, spiral assisted slag discharge water jet high-pressure drill pipe and high-pressure rotary joint, combining with remote monitoring and control of underground hydraulic operation. The field monitoring results show that the average gas concentration and the mixing amount of gas extraction increased to 2. 75 times and 1. 81 times of that of the conventional hole by the method of permeability-increasing drilling, which indicates that the permeability-increasing effect of the proposed technology is remarkable.

国家科技重大专项资助项目(2016ZX05067-005-002)

任仲久. 导向槽定向水力压裂煤层增透强化瓦斯抽采技术及应用 [J]. 煤炭工程, 2024, 56(2): 131-137.