中文摘要：

水平井筒附近应力场分布复杂，往往造成水力裂缝转向，但目前对于水平井筒附近水力裂缝空间转向规律的认识还不够深入。为了研究水平井筒附近水力裂缝的三维延伸规律，基于最大拉伸应力准则和拉格朗日极值法建立了水平井筒附近水力裂缝空间转向模型，用于分析三向地应力和井筒内压作用下水平井筒水力裂缝的起裂位置和扩展形状。根据此模型，编制了数值计算程序。针对所建立的理论模型，在真三轴水力压裂模拟装置上采用岩石试样进行了物理模拟，模型计算结果与物理模拟结果基本一致。通过模拟计算和物理试验，得到了井筒附近水力压裂裂缝空间转向的基本规律。研究结果表明，水平井井筒附近水力裂缝的空间转向确实存在，裂缝转向前的距离随井简方位角增加而增加，但增加幅度大致在3倍井筒直径的范围内。

英文摘要：

The complicate stress distribution around horizontal well-bore makes hydraulic fracture reorientation happen, but the principles behind the reorientation are poorly understood. A three-dimensional reorientation model for hydraulic fractures around horizontal well-bores is established, based on the maximum tensile stress criterion and the Lagrange Multiplier method. The model can be used to analyze initiation position and propagation shapes of hydraulic fracture, with three geo-stresses and well-bore pressure being considered. Numerical codes are made for simulation. Based on theoretical model, laboraroty experiments with rock samples are performed on the true tri-axis simulation equipment for hydraulic fracturing. The numerical results from the theoretical model are basically consistent with those of experiments. The results indicate that the three-dimensional reorientation of hydraulic fractures around horizontal well-boles exists, and the distance away from a well-bore after reorientation increases when the well-bore orientation becomes larger, and generally occurs within three times the size of well-bore diameter.