ARMA 12-395 Open-System Geomechanics of Rocks with Variable Solid Mass

摘要

The Open-System Geomechanics Model (OSG) provides a fully coupled description of stress/strain, solid and fluid masses evolution initiated by phase transformation (desorption, dehydration, or dissolution/precipitation) between solid and fluid components. The model consists of new constitutive relationships, which capture variation of eigen-strain caused by variation of solid and fluid mass and new equations of equilibrium for solid phase, fluid mass and heat transfer equations. A new model of coal-bed methane (CBM) permeability is derived based on OSG approach. The new model of sorption-induced permeability vs. pressure provides significantly better agreement with experiment data compared to previously published permeability models.