Non-equilibrium thermodynamics for fully coupled thermal hydraulic mechanical chemical processes

In this paper, a pioneering approach of reactive transport in porous media is introduced, which model thermal–hydraulic–mechanical–chemical processes. The novelties of this approach are: (i) non-equilibrium thermodynamics which is used as a unifying framework relating generalized fluxes to forces and (ii) fully coupled integration of the multi-physics processes, introduced within the framework of large transformations including logarithmic finite strain and co-rotational rates. This formulation opens the horizons for complex simulations which were difficult to conduct previously because of the lacking bridges between non-linear computational mechanics and reactive transport processes. As an illustration of the model, a sample of simple geometry is subjected to a non-linear deformation beyond the reversible regime. This perturbation from equilibrium produces a permanent deformation, an overpressure and a temperature change. The subsequent thermodynamic conditions trigger chemical reactions among the aqueous species which are not necessarily in equilibrium with their environment. The deformation also induces a change of porosity which affects the permeability as well as the pore pressure distribution.