眼前山铁矿水压致裂矿岩预处理裂隙扩展研究

Crack extension of hydraulic fractures Induced by preconditioning in Yanqianshan iron mine

水压致裂预处理技术是大幅改善硬岩矿山矿岩可崩性的关键技术,选用合适压裂能力的设备以及压裂钻孔布置是工业应用中的重要工作。本文基于眼前山铁矿开展的水压致裂矿岩预处理试验,采用微地震定位及水位观测的方法对岩石水力裂缝扩展距离、破裂面方向等进行了分析。结果表明:当注水泵量为150L/min时水力裂缝扩展距离最大可达34m,平均值为24.54m,该泵量下1500s内裂缝已充分扩展;微地震平面分布的长轴方向与区域上水平最大主应力方向近乎一致;水压致裂试验产生的破裂面法线方向为最小主应力方向。

Pre-conditioning by hydraulic fracturing is a key technology to greatly increase caveability of hard rock mines,and selection of suitable powerful fracturing equipment and layout of fracturing holes is an important work in industry application.Based on field test of preconditioning by hydraulic fracturing in Yanqianshan ore mine,some core characteristics such as fracture extending distance,azimuth and fracture direction were analyzed by using microearthquake location and water level monitoring method.The results show that the maximum fracture extending distance was about 34m,the average value was 24.54m,and the fracture fully extended in 1500 seconds when the pumping flow rate was 150L/min.Major axis direction of microearthquake distribution plane was closed to the maximum horizontal principal stress direction,normal direction of fracture plane caused by hydraulic fracturing was closed to the minimum principal stress direction.