Abstract The mechanical heterogeneity of unconventional gas reservoirs is a significant factor affecting the nucleation and propagation of hydraulic fractures. The ignorance of mechanical heterogeneity in the numerical calculation has been demonstrated to result in huge deviations from actual fracture propagation. In the present study, the eXtended Finite Element Method (XFEM) is used to simulate the propagation of a hydraulic fracture in a heterogeneous reservoir. The evolution of a hydraulic fracture encountering hard blocks at different positions near the initial fracture tip is investigated. The mechanical heterogeneity of reservoir rock leads to the redistribution of strength and stress, which eventually affects the evolution of hydraulic fracture. The effects of soft-hard rock interbedding and randomly distributed irregular blocks are also investigated. Generally, the hard blocks distributed in a reservoir promote the growth of hydraulic fracture in length, but limit the fracture growth in width.

中文翻译：

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机械非均质性对非常规气藏水力裂缝扩展的影响

摘要 非常规气藏的力学非均质性是影响水力裂缝成核和扩展的重要因素。数值计算中对机械非均质性的忽视已被证明会导致与实际裂缝扩展的巨大偏差。在本研究中，扩展有限元方法 (XFEM) 用于模拟非均质油藏中水力压裂的扩展。研究了在初始裂缝尖端附近不同位置遇到硬块的水力压裂的演化。储集岩的力学非均质性导致强度和应力的重新分布，最终影响水力压裂的演化。还研究了软硬岩互层和随机分布的不规则块体的影响。一般来说，分布在储层中的硬块在长度上促进了水力裂缝的生长，但在宽度上限制了裂缝的生长。