Poroelasticity theory of chemically active clay shales

The deformation tensor ε in a porous medium is a function of the stress tensor σ and the pore pressure ρ. Additional osmotic effects are present in some rocks, such as shales. It is shown that such effects, in turn, modify the thermodynamics of the system, namely, in terms of the internal energy of the additional term due to the chemical potential μ^r of all the chemical components in the pore fluid. Because of this, an additional term due to the chemical potentials appears in the strain-stress relations.