Modeling of sorption-induced deformations of porous materials due to surface adsorption, capillary effects, and cavitation

A clear understanding of the physical mechanisms behind the sorption-induced deformation of porous materials is essential for a variety of applications, e.g., natural gas production from and CO₂ sequestration into coalbed and shale formations. To describe the deformation of partially saturated porous materials with a wide pore size distribution, El Tabbal et al. (2020) proposed a poromechanical model derived from thermodynamic considerations. In our work, we propose a derivation of El Tabbal's model in a Lagrangian form and improve it by 1) considering the specificity of the fluid adsorption on the pore surface and 2) modeling the strain variation during the adsorbate cavitation. We validate the model by applying it to sorption and strain isotherms measured by various authors with a variety of adsorbate/adsorbent couples. We then study the impact of several uncertainties on the shape of the strain isotherm, namely the cavitation pressure, the experimentally defined “dry state”, and the calculated BET-specific surface area. The model is capable of predicting the shape of strain isotherms without any fitting parameters.