Thermodynamic Characterization of Chemical Damage in Variably Saturated Water-Active Shales

Abstract A constitutive framework is developed for variably saturated water-active swelling rocks undergoing chemical damage using modified mixture theory and continuum mechanics. The Helmholtzian thermodynamic potential the skeletal system derived as a function of state variables including deformation, damage, two-phase fluid pressures, potential. Using this, in addition to chemo-poroelastic equations, thermodynamically consistent first-order estimation variable developed. working shown through numerical example water uptake clay-rich shale solved by finite element method. results portray significance conditions equations unique damage-dependent poroelastic behavior was observed wet dry regions. theoretical-based corroborated previous experimental observations illustrates that rock strength dominantly controlled time exposure rather than level saturation. Contrary what perceived, show responses do not coincide even less reactive shales due time-dependent water-induced microstructural deterioration rock. increases storage flow capacity water-saturated region giving rise substantive spatio-temporal changes matrix stresses. research findings provide valuable insights understand how poromechanics plays role causing water-sensitive such coupled with associated damage.