煤层冲刷带酸化压裂硬岩软化技术应用研究

Study on Application of Acidification and Softening Technology for Fracturing of Hard Rock in Scour Zone of Coal Seam

针对新疆阿克苏榆树河煤矿煤层冲刷带硬岩截割问题开展了井下压裂酸化软化技术的工程试验研究。该技术实现了井下钻孔一次性整体压裂,通过物理实验、数值模拟、理论分析等方法,对不同压裂液进行工业性对比试验,得出CO_(2)耦合压裂液其渗透性强,在压裂过程中能够有效地降低压裂裂隙起裂峰值,更好地进入到岩体的介孔、微孔中增加其含水率;同时其弱酸性对岩石颗粒骨架部分性质有腐蚀劣化的作用,提高预裂软化效果,相比其他强酸性压裂液在煤矿井下更具有实用性。压裂实施后,工作面回采速度提高了83%,截齿消耗减少了340个,降低了生产成本,保障了生产效率。工程试验成果可为含硬岩的复杂煤层开采提供借鉴。

Engineering experimental research on downhole fracturing acid softening technology was carried out for the problem of hard rock interception in the coal seam washout zone of Yushuhe coal mine in Aksu, Xinjiang. The technology realizes one-time overall fracturing in downhole borehole, and through physical experiments, numerical simulation and theoretical analysis, different fracturing fluids are tested for industrial comparisons, and it is concluded that CO_(2)coupling fracturing fluid has strong permeability and can effectively reduce the fracture initiation peak in the fracturing process, and better enter into the mesopores and micropores of the rock to increase its water content;meanwhile, its weak acidity has a corrosive deterioration effect on the skeleton part of the rock particles. At the same time,its weak acidity has a corrosive deterioration effect on the skeletal part of rock particles and improves the pre-fracture softening effect, which is more practical than other strongly acidic fracturing fluids in coal mines. After the implementation of fracturing, the working face recovery speed increased by 83%and the consumption of cut-off teeth decreased by 340, which reduced the production cost and ensured the production efficiency. The results of the engineering test can provide a reference for the mining of complex coal seams containing hard rock.