Investigation of the permeability anisotropy of porous sandstone induced by complex stress conditions

The permeability of hydrocarbon reservoirs composed of porous rock is anisotropic under asymmetrical stress configuration. A proper understanding of this characteristic is essential for an accurate prediction of flow capacity. The permeability sensitivity of porous sandstone to stresses is investigated by experiments and discrete element method simulations. Based on the rhombic-packed granular system, an analytical model is proposed to quantitively calculate the components of tensorial permeability affected by stresses and to evaluate the evolution of permeability anisotropy. The permeability decrement is more sensitive to the principal stress perpendicular to its seepage direction than that parallel with. The intrinsic relationships between the sensitivity behaviors under different stress conditions are revealed according to the variation of flow apertures, which is controlled by the micro sensitivity factor α. The prediction of permeability sensitivity behaviors and anisotropy to stresses are consistent with the experimental and simulated results. Deviatoric stress can induce high permeability anisotropy in initially-homogenous porous reservoirs and produce a preferential flow path perpendicular to minimum principal stress. •Studies are conducted to reveal the permeability sensitivity of porous rock to stress.•An analytical method is proposed to calculate the tensorial permeability.•The permeability decrements are controlled by the distribution of flow apertures.•Deviatoric stress induces high permeability anisotropy in homogenous rocks.