A deformation-dependent model for permeability changes in oil sand due to shear dilation

Thermal recovery processes such as cyclic steam stimulation and steam assis ted gravity drainage induce significant shear dilation in oil sand formatio ns. Shear dilation deformation results in an increase in pore volume, there by enhancing permeability. In previous studies, it was assumed that the cha nge in absolute permeability is a function of porosity or volumetic strain, which is. in turn, a function of mean or minimum effective stress. In such conventional semi-empirical correlations (e.g., the Kozeny-Carman equation ), the changes in permeability are equal in all directions even though the changes in strains are different in each direction. This paper proposes a n ew deformation-dependent permeability model for the shear dilation of oil s ands. This model is based on a granular interaction approach. The fundament al approach accounts for how pore throat areas along flow channels and grai n contacts change with shear dilation. This allows one to quantify the evol ution of changes in permeability in one direction under continuous shearing . The model explicitly states that the permeability changes are highly anis otropic, dependent on the induced principal strains. Comparison with experi mental data is presented to show the validity of the proposed model. In add ition, the proposed model is extended and formulated in a generalized 3D te nsor notation so that it can be implemented into existing reservoir or coup led geomechanics-reservoir simulators.