In fractured geothermal reservoirs, the fracture networks and internal fluid flow behaviors can significantly impact the thermal performance. In this study, we proposed a non-Darcy rough discrete fracture network (NR-DFN) model that can simultaneously consider the fracture evolution and non-Darcy flow dynamics in studying the thermo-hydro-mechanical (THM) coupling processes for heat extraction in geothermal reservoir. We further employed the model on the Habanero enhanced geothermal systems (EGS) project located in Australia. First, our findings illustrate a clear spatial-temporal variation in the thermal stress and pressure perturbations, as well as uneven spatial distribution of shear failure in 3D fracture networks. Activated shear failure is mainly concentrated in the first fracture cluster. Secondly, channeling flow have also been observed in DFNs during heat extraction and are further intensified by the expansion of fractures driven by thermal stresses. Moreover, the combined effect of non-Darcy flow and fracture evolution triggers a rapid decline in the resulting heat rate and temperature. The NR-DFN model framework and the Habanero EGS’s results illustrate the importance of both fracture evolution and non-Darcy flow on the efficiency of EGS production and have the potential to promote the development of more sustainable and efficient EGS operations for stakeholders.

中文翻译：

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裂缝演化和非达西流对三维复杂裂隙岩增强地热系统热性能的影响


在裂缝性地热储层中，裂缝网络和内部流体流动行为会显着影响热性能。在本研究中，我们提出了一种非达西粗糙离散裂缝网络（NR-DFN）模型，该模型可以在研究热提取的热-水-机械（THM）耦合过程时同时考虑裂缝演化和非达西流动动力学。地热储库。我们进一步在位于澳大利亚的 Habanero 增强型地热系统 (EGS) 项目中应用了该模型。首先，我们的研究结果表明热应力和压力扰动存在明显的时空变化，以及 3D 裂缝网络中剪切破坏的不均匀空间分布。激活剪切破坏主要集中在第一裂缝群。其次，在热提取过程中，DFN 中也观察到了沟流，并且热应力驱动的裂缝扩展进一步加剧了沟流。此外，非达西流和裂缝演化的综合效应引发了热耗率和温度的快速下降。 NR-DFN模型框架和Habanero EGS的结果说明了裂缝演化和非达西流对EGS生产效率的重要性，并有可能促进利益相关者开发更可持续和更高效的EGS运营。