In order to obtain the mechanism of crack propagation of oriented perforation hydraulic fracture and its effect on mechanical properties of rock samples, an experimental study on hydraulic fracture of rock samples without confining pressure was carried out. The confining pressure ratio coefficient was defined, and oriented perforation hydraulic fracture was numerically simulated based on the extended finite element method so as to explore the comprehensive influence of different perforation parameters. The results demonstrated that the crack initiates and propagates along the direction of perforation azimuth angle, and the crack of oriented perforation is slightly wider than that of non-oriented perforation. The difficulty of crack initiation and turning increases with the perforation azimuth angle and decreases with the confining pressure ratio coefficient. Crack initiation and propagation are mainly driven by tensile stress, and the crack initiation pressure increases with the perforation azimuth angle and the confining pressure ratio coefficient.

为了获得定向射孔水力裂缝的裂纹扩展机理及其对岩石样品力学性能的影响，进行了无围压的岩石样品水力裂缝实验研究。定义围压比系数，并基于扩展有限元方法对定向射孔水力压裂进行数值模拟，以探讨不同射孔参数的综合影响。结果表明，裂纹沿射孔方位角的方向萌生并扩展，定向射孔的裂纹比非定向射孔的裂纹稍宽。裂纹产生和转向的难度随着射孔方位角的增加而增加，并随着围压比系数的降低而减小。裂纹的萌生和扩展主要由拉应力驱动，裂纹的萌生压力随射孔方位角和围压比系数的增加而增大。