In this paper, a fully coupled thermo‐hydro‐mechanical model is presented for two‐phase fluid flow and heat transfer in fractured/fracturing porous media using the extended finite element method. In the fractured porous medium, the traction, heat, and mass transfer between the fracture space and the surrounding media are coupled. The wetting and nonwetting fluid phases are water and gas, which are assumed to be immiscible, and no phase‐change is considered. The system of coupled equations consists of the linear momentum balance of solid phase, wetting and nonwetting fluid continuities, and thermal energy conservation. The main variables used to solve the system of equations are solid phase displacement, wetting fluid pressure, capillary pressure, and temperature. The fracture is assumed to impose the strong discontinuity in the displacement field and weak discontinuities in the fluid pressure, capillary pressure, and temperature fields. The mode I fracture propagation is employed using a cohesive fracture model. Finally, several numerical examples are solved to illustrate the capability of the proposed computational algorithm. It is shown that the effect of thermal expansion on the effective stress can influence the rate of fracture propagation and the injection pressure in hydraulic fracturing process. Moreover, the effect of thermal loading is investigated properly on fracture opening and fluids flow in unsaturated porous media, and the convective heat transfer within the fracture is captured successfully. It is shown how the proposed computational model is capable of modeling the fully coupled thermal fracture propagation in unsaturated porous media.

中文翻译：

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使用X-FEM技术对具有两相流体流动的压裂多孔介质进行热-水-力学建模

在本文中，使用扩展有限元方法，提出了一种完全耦合的热-水-力学模型，用于在裂隙/压裂多孔介质中的两相流体流动和传热。在压裂的多孔介质中，压裂空间与周围介质之间的牵引力，热量和质量传递是耦合的。润湿相和非润湿相都是水和气体，假定是不溶混的，因此不考虑相变。耦合方程组由固相的线性动量平衡，润湿和不润湿的流体连续性以及热能守恒组成。用于求解方程组的主要变量是固相位移，润湿液压力，毛细管压力和温度。假定该裂缝在位移场中施加强不连续性，而在流体压力，毛细管压力和温度场中施加弱不连续性。使用内聚裂缝模型采用I型裂缝扩展。最后，通过几个数值例子来说明所提出的计算算法的功能。结果表明，热膨胀对有效应力的影响会影响水力压裂过程中裂缝的扩展速度和注入压力。此外，适当研究了热负荷对裂缝开度和不饱和多孔介质中流体流动的影响，并成功地捕获了裂缝内的对流传热。