Gas intrusion in saturated bentonite – A thermodynamic approach

A homogeneous and isotropic model of pressure response in saturated bentonite with high montmorillonite content is presented. The model is based on basic thermodynamic relations and is characterized by one single function, Ps(w), the measured swelling pressure for a given water ratio. It is applied to gas intrusion in saturated bentonite, a process of great practical interest, and gives both a simple criteria for gas intrusion as well as providing a theoretical framework for interpreting gas migration experiments. The predictions of the model are found to agree well with literature data on Wyoming type bentonite (MX-80).