Abstract The exploration and production of unconventional reservoirs, such as tight-gas sand, gas and oil shales, and geothermal deposits, require hydraulic fracturing treatments to increase reservoir permeability and enhance its production. However, the presence of natural fractures alters hydraulic fracture propagation through the rock formation. This interaction may lead to complex fracture networks, which can connect with shallower aquifers or geological faults increasing the risk of fault reactivation. This work presents a numerical technique using the finite element method to study the interaction between hydraulic fracture and natural fractures to predict the direction of fracture propagation. Fractures are modeled using a coupled hydro-mechanical zero-thickness interface element. A damage constitutive relationship describes the behavior of the hydraulic fractures. Natural fractures follow the Mohr-Coulomb constitutive model. Three-dimensional numerical models are simulated to study hydraulic fracture propagation and its interaction with pre-existing natural fractures. The numerical results show good agreement with experimental tests. The three main possibilities of fracture interaction (arrest, opening, and crossing) are predicted. The effect of in-situ stresses, fracture orientation, friction angle, injection flow rate and distance from the borehole to natural fracture are also investigated. The results highlight that the most important parameters affecting fracture interaction are the in-situ stresses and angle of approach between hydraulic fracture and natural fracture. Finally, this methodology can support the prediction of complex fracture network behavior in field conditions.

中文翻译：

---

三维断裂相互作用的数值模拟

摘要 致密气砂岩、气油页岩、地热矿床等非常规储层的勘探开发，需要通过水力压裂处理来提高储层渗透率，提高产量。然而，天然裂缝的存在改变了水力裂缝在岩层中的传播。这种相互作用可能导致复杂的裂缝网络，这些裂缝网络可以与较浅的含水层或地质断层相连，从而增加断层再激活的风险。这项工作提出了一种使用有限元方法的数值技术来研究水力裂缝和天然裂缝之间的相互作用，以预测裂缝扩展的方向。使用耦合的液压机械零厚度界面元素对裂缝进行建模。损伤本构关系描述了水力压裂的行为。天然裂缝遵循 Mohr-Coulomb 本构模型。模拟三维数值模型以研究水力裂缝扩展及其与预先存在的天然裂缝的相互作用。数值结果与实验测试显示出良好的一致性。预测了裂缝相互作用的三种主要可能性（停止、打开和交叉）。还研究了原位应力、裂缝方向、摩擦角、注入流速和钻孔到天然裂缝的距离的影响。结果表明，影响裂缝相互作用的最重要参数是地应力和水力裂缝与天然裂缝之间的接近角。最后，