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)...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.展开更多
This paper presents the development of a coupled modeling approach to simulate cryogenic thermo-hydro-mechanical(THM)processes associated with a freezing medium,which is then implemented in the combined finite-discret...This paper presents the development of a coupled modeling approach to simulate cryogenic thermo-hydro-mechanical(THM)processes associated with a freezing medium,which is then implemented in the combined finite-discrete element method code(FDEM)for multi-physics simulation.The governing equations are deduced based on energy and mass conservation,and static equilibrium equations,considering water/ice phase change,where the strong couplings between multi-fields are supplemented by critical coupling parameters(e.g.unfrozen water content,permeability,and thermal conductivity).The proposed model is validated against laboratory and field experiments.Results show that the cryogenic THM model can well predict the evolution of strongly coupled processes observed in frozen media(e.g.heat transfer,water migration,and frost heave deformation),while also capturing,as emergent properties of the model,important phenomena(e.g.latent heat,cryogenic suction,ice expansion and distinct three-zone distribution)caused by water/ice phase change at laboratory and field scales,which are difficult to be all revealed by existing THM models.The novel modeling framework presents a gateway to further understanding and predicting the multi-physical coupling behavior of frozen media in cold regions.展开更多
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)+2 种基金Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical EngineeringInstitute of Rock and Soil MechanicsChinese Academy of Sciences (No.SKLGME022009)。
文摘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.
基金supported by the Natural Sciences and Engineering Research Council of Canada (NSERC)Discovery Grants 341275,NSERC CRDPJ 543894-19,and NSERC/Energi Simulation Industrial Research Chair programfunding he received from Lassonde International Graduate Scholarship in Mining at the University of Toronto+1 种基金supported by the FCE Start-up Fund for New Recruits at the Hong Kong Polytechnic University (P0034042)the Early Career Scheme and the General Research Fund Scheme of the Research Grants Council of the Hong Kong SAR,China (Project Nos.PolyU 25220021 and PolyU 15227222).
文摘This paper presents the development of a coupled modeling approach to simulate cryogenic thermo-hydro-mechanical(THM)processes associated with a freezing medium,which is then implemented in the combined finite-discrete element method code(FDEM)for multi-physics simulation.The governing equations are deduced based on energy and mass conservation,and static equilibrium equations,considering water/ice phase change,where the strong couplings between multi-fields are supplemented by critical coupling parameters(e.g.unfrozen water content,permeability,and thermal conductivity).The proposed model is validated against laboratory and field experiments.Results show that the cryogenic THM model can well predict the evolution of strongly coupled processes observed in frozen media(e.g.heat transfer,water migration,and frost heave deformation),while also capturing,as emergent properties of the model,important phenomena(e.g.latent heat,cryogenic suction,ice expansion and distinct three-zone distribution)caused by water/ice phase change at laboratory and field scales,which are difficult to be all revealed by existing THM models.The novel modeling framework presents a gateway to further understanding and predicting the multi-physical coupling behavior of frozen media in cold regions.
