Effects of fracture evolution and non-Darcy flow on the thermal performance of enhanced geothermal system in 3D complex fractured rock  

作　　者：Yachen Xie Jianxing Liao Pengfei Zhao Kaiwen Xia Cunbao Li 

机构地区：[1]Department of Civil and Mineral Engineering,University of Toronto,Toronto M5S1A4,Canada [2]College of Water Resources and Hydropower,Sichuan University,Chengdu 610225,China [3]State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Wuhan 430071,China [4]College of Civil Engineering,Guizhou University,Guiyang 550025,China [5]Institute of Geosafety,School of Engineering and Technology,China University of Geosciences,Beijing 100083,China [6]State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering,Shenzhen University,Shenzhen 518060,China

出　　处：《International Journal of Mining Science and Technology》2024年第4期443-459,共17页矿业科学技术学报（英文版）

基　　金：funded by the National Natural Science Foundation of China (No.U22A20166);Science and Technology Foundation of Guizhou Province (No.QKHJC-ZK[2023]YB074);Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering;Institute of Rock and Soil Mechanics;Chinese Academy of Sciences (No.SKLGME022009)。

摘　　要：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.

关 键 词：Coupled THM model Non-Darcy flow Deformable DFN Enhanced geothermal systems 

分 类 号：P314[天文地球—固体地球物理学] TK521[天文地球—地球物理学]