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掌握储层水力压裂裂缝的起裂与扩展规律对非常规油气资源开采和提高采收率至关重要。采用水泥砂浆模拟天然页岩,获得了与页岩基本力学参数和断裂韧性一致的相似材料。运用FRANC3D和ANSYS,模拟分析了不同水平应力比和射孔布置方式对水力压裂起裂和扩展的影响。研究表明:利用FRANC3D+ANSYS可以较好地模拟射孔压裂裂缝的起裂和三维空间中的扩展行为。射孔压裂裂缝的起裂压力随水平应力比的增大而减小。射孔方向与最大水平主应力方向一致时起裂压力较小,射孔方向与最大水平主应力成夹角时,裂缝扩展面扭转并趋向于平行最大水平主应力方向。相对于射孔对称排布和交错排布,射孔线性排布时的起裂压力较小。
Grasping the law of initiation and propagation of hydraulic fracturing in fractured reservoirs is crucial for unconventional oil and gas resource recovery and enhanced oil recovery. Cement mortar was used to simulate natural shale, and similar materials with shale basic mechanics parameters and fracture toughness were obtained. Using FRANC3D and ANSYS, the influence of different horizontal stress ratio and perforation layout on the initiation and propagation of hydraulic fracturing was simulated. The research shows that the FRANC3D + ANSYS can well simulate the initiation and propagation of perforation fractures and the expansion behavior in three-dimensional space. The initiation pressure of perforation fractures decreases with the increase of horizontal stress ratio. When the direction of perforation coincides with the direction of the maximum horizontal principal stress, the cracking pressure is small and the direction of perforation is at an angle to the maximum horizontal principal stress, the crack propagation surface is twisted and tends to the direction of maximum parallel principal stress. Relative to the perforated symmetry and staggered arrangement, perforating linear arrangement of the cracking pressure is small.