Unconventional hydrocarbon reservoirs in layered formations, such as tight sandstones and shales, are continually being developed. Hydraulic fracturing is a critical technology for the high-efficiency development of hydrocarbon reservoirs. Understanding the stress field and stability of the formation interface is vital to understanding stress propagation, preferably before the growing hydraulic fracture contacts the formation interface. In this study, models are developed for computing the stress field of hydraulic fracture propagation near the formation interface, and the stress fields within and at the two sides of the formation interface are analyzed. Four failure modes of the interface under the impact of hydraulic fracture propagation in its vicinity are identified, and the corresponding failure criteria are proposed. By simulating the magnitude and direction of peak stress at different parameters, the failure mode and stability of the formation interface are analyzed. Results reveal that when the interface strength is weak, the formation interface fails before the growing hydraulic fracture contacts it, and its stability is significantly related to a variety of factors, including the type of formation interface, rock mechanical properties, far-field stress, structural parameters, distance between the hydraulic fracture and formation interface, and fracturing execution parameters.

中文翻译：

---

水力压裂扩展在地层界面附近影响下地层界面的稳定性

诸如致密砂岩和页岩之类的分层地层中的非常规油气藏正在不断开发中。水力压裂是高效开发油气藏的关键技术。了解应力场和地层界面的稳定性对于理解应力传播至关重要，最好是在不断增长的水力压裂接触地层界面之前。在这项研究中，建立了用于计算在地层界面附近的水力压裂扩展的应力场的模型，并分析了地层界面内部和两侧的应力场。确定了界面附近水力压裂扩展影响下的四种失效模式，并提出了相应的失效准则。通过模拟不同参数下峰值应力的大小和方向，分析了地层界面的破坏模式和稳定性。结果表明，当界面强度弱时，地层界面在不断增长的水力压裂接触之前就失效了，其稳定性与多种因素显着相关，包括地层界面的类型，岩石力学特性，远场应力，结构参数，水力压裂与地层界面之间的距离以及压裂执行参数。