This paper develops a phase-field approach to model hydro-thermally induced crack propagation in thermo-poroelastic media. Both thermal conduction and convection, and the fully thermo-poroelastic coupled effect are taken into consideration in the phase-field model. The fluid content is influenced by the volumetric strain, temperature, and pressure. The heat flux is susceptible to temperature change and fluid flux. The injection fluid pressure and thermal loading trigger the variation of elastic energy, and then drive crack propagation, which is captured by the phase-field variable. A segregated solution scheme and the finite element implementation details are provided here for solving the nonlinear thermo-poroelastic problem. Several examples are tested to verify the present approach and to show its ability to simulate hydro-thermally induced crack propagation in the application of cold fluid injection in a cracked reservoir. The numerical results indicate that the development of the thermal effect on crack propagation is slow when compared with that of the fluid pressure. The present approach can serve as a convenient simulation tool for crack propagation in geothermal and oil/gas reservoir developments.

本文开发了一种相场方法来模拟热多孔弹性介质中的水热诱导裂纹扩展。相场模型同时考虑了热传导和对流以及完全热-多孔弹性耦合效应。流体含量受体积应变、温度和压力的影响。热通量易受温度变化和流体通量的影响。注入流体压力和热载荷触发弹性能的变化，然后驱动裂纹扩展，由相场变量捕获。这里提供了一个分离的解决方案和有限元实现细节，用于解决非线性热多孔弹性问题。测试了几个例子来验证本方法并显示其在裂缝储层中应用冷流体注入时模拟水热诱导裂缝扩展的能力。数值结果表明，与流体压力相比，热效应对裂纹扩展的发展缓慢。本方法可用作地热和油气藏开发中裂缝扩展的便捷模拟工具。