Publication Details

Category Text Publication
Reference Category Journals
DOI 10.1016/j.ijrmms.2009.01.008
Title (Primary) Numerical simulation of thermal-hydrologic-mechanical-chemical processes in deformable, fractured porous media
Author Taron, J.; Elsworth, D.; Min, K.-B.
Source Titel International Journal of Rock Mechanics and Mining Sciences
Year 2009
Department ENVINF
Volume 46
Issue 5
Page From 842
Page To 854
Language englisch
Keywords THMC; Geothermal simulation; CO2; Fracture reactive transport; Reservoir permeability; Dual porosity
Abstract A method is introduced to couple the thermal (T), hydrologic (H), and chemical precipitation/dissolution (C) capabilities of TOUGHREACT with the mechanical (M) framework of FLAC3D to examine THMC processes in deformable, fractured porous media. The combined influence of stress-driven asperity dissolution, thermal-hydro-mechanical asperity compaction/dilation, and mineral precipitation/dissolution alter the permeability of fractures during thermal, hydraulic, and chemical stimulation. Fracture and matrix are mechanically linked through linear, dual-porosity poroelasticity. Stress-dissolution effects are driven by augmented effective stresses incrementally defined at steady state with feedbacks to the transport system as a mass source, and to the mechanical system as an equivalent chemical strain. Porosity, permeability, stiffness, and chemical composition may be spatially heterogeneous and evolve with local temperature, effective stress and chemical potential. Changes in total stress generate undrained fluid pressure increments which are passed from the mechanical analysis to the transport logic with a correction to enforce conservation of fluid mass. Analytical comparisons confirm the ability of the model to represent the rapid, undrained response of the fluid-mechanical system to mechanical loading. We then focus on a full thermal loading/unloading cycle of a constrained fractured mass and follow irreversible alteration in in-situ stress and permeability resulting from both mechanical and chemical effects. A subsequent paper [Taron J, Elsworth D. Thermal-hydrologic-mechanical-chemical processes in the evolution of engineered geothermal reservoirs. Int J Rock Mech Min Sci 2009; this issue, doi:10.1016/j.ijrmms.2009.01.007] follows the evolution of mechanical and transport properties in an EGS reservoir, and outlines in greater detail the strength of coupling between THMC mechanisms.
Persistent UFZ Identifier
Taron, J., Elsworth, D., Min, K.-B. (2009):
Numerical simulation of thermal-hydrologic-mechanical-chemical processes in deformable, fractured porous media
Int. J. Rock Mech. Min. Sci. 46 (5), 842 - 854 10.1016/j.ijrmms.2009.01.008