Upper and lower dissipative bounds for THMC Coupling

The ability to understand and predict how thermal, hydrological, mechanical and chemical (THMC) processes interact is fundamental to the exploration, stimulation and exploitation of natural and enhanced geothermal systems. Because of the complexity of THMC coupling exact solutions are hard or impossible to find. Therefore, a new perspective is required for assessing upper and lower bounds of dissipation in such simulations. We present (i) such a new Thermal-Hydrological-Mechanical-Chemical (THMC) coupling formulation, based on non-equilibrium thermodynamics; (ii) show how THMC feedback is incorporated in the thermodynamics approach; (iii) suggest a unifying thermodynamic framework for coupling across scales and (iv) formulate a new rationale for assessing upper and lower bounds of dissipation for THMC processes. Using forward simulations these bounds can be used for assessing uncertainties of material properties as a function of independent variables (e.g. temperature, pressure, damage, grain size, chemistry, strain...). At the large scale the bounds can be used to characterize uncertainties of geothermal fluid extraction from natural and stimulated geothermal reservoirs.
Upper and lower bounds of dissipation Boundary conditions applied to the model boundary for THMC coupling