Multiphase mass and heat transfer are ubiquitous in the subsurface within manifold applications. The presence of fractures over several scales and complex geometry magnifies the uncertainty of the heat transfer phenomena, which will significantly impact, or even dominate, the dynamic transport process. Capturing the details of fluid and heat transport within the fractured system is beneficial to the subsurface operations. However, accurate modeling methodologies for thermal high-enthalpy multiphase flow within fractured reservoirs are quite limited. In this work, multiphase flow in fractured geothermal reservoirs is numerically investigated. A discrete-fracture model is utilized to describe the fractured system. To characterize the thermal transport process accurately and efficiently, the resolution of discretization is necessarily optimized. A synthetic fracture model is firstly selected to run on different levels of discretization with different initial thermodynamic conditions. A comprehensive analysis is conducted to compare the convergence and computational efficiency of simulations. The numerical scheme is implemented within the Delft Advanced Research Terra Simulator (DARTS), which can provide fast and robust simulation to energy applications in the subsurface. Based on the converged numerical solutions, a thermal Péclet number is defined to characterize the interplay between thermal convection and conduction, which are the two governing mechanisms in geothermal development. Different heat transfer stages are recognized on the Péclet curve in conjunction with production regimes of the synthetic fractured reservoir. A fracture network, sketched and scaled up from a digital map of a realistic outcrop, is then utilized to perform a sensitivity analysis of the key parameters influencing the heat and mass transfer. Thermal propagation and Péclet number are found to be sensitive to flow rate and thermal parameters (e.g., rock heat conductivity and heat capacity). This paper presents a numerical simulation framework for fractured geothermal reservoirs, which provides the necessary procedures for practical investigations regarding geothermal developments with uncertainties.

多相传质和传热在多种应用中的地下无处不在。多个尺度和复杂几何形状的裂缝的存在放大了传热现象的不确定性，这将显着影响甚至主导动态传输过程。捕获压裂系统内流体和热传输的细节有利于地下作业。然而，裂缝性储层内热高焓多相流的准确建模方法非常有限。在这项工作中，对裂缝性地热储层中的多相流进行了数值研究。离散断裂模型用于描述断裂系统。为了准确有效地表征热传输过程，必须优化离散化的分辨率。首先选择合成断裂模型，以在具有不同初始热力学条件的不同离散化水平上运行。进行综合分析以比较模拟的收敛性和计算效率。该数值方案在代尔夫特高级研究 Terra Simulator (DARTS) 中实施，它可以为地下的能源应用提供快速而稳健的模拟。基于收敛的数值解，定义了热 Péclet 数来表征热对流和传导之间的相互作用，这是地热开发中的两种控制机制。在 Péclet 曲线上结合合成裂缝性油藏的生产方式识别出不同的传热阶段。一个断裂网络，从真实露头的数字地图绘制并放大，然后用于对影响传热和传质的关键参数进行敏感性分析。发现热传播和 Péclet 数对流速和热参数（例如，岩石热导率和热容量）很敏感。本文提出了裂缝性地热储层的数值模拟框架，为具有不确定性的地热开发的实际调查提供了必要的程序。