Effect of fines migration on oil–water relative permeability during two-phase flow in porous media

•Lower damage by salinity reduction at the presence of remaining oil was observed.•Rel Perm were determined by modified JBN method for core flood with fines migration.•Water Rel Perm curve showed decline at high saturations due to fines migration.

One of the main physical characteristics defining oil recovery during water injection is the phase relative permeability. Salinity of the formation water can significantly differ from the injected water and consequently affect the relative permeabilities.In the current work, we investigate the effect of fines migration on water and oil relative permeability. First, flow tests with piece-wise constant decreasing water salinity without oil are performed in order to identify the movable fine particles. Then the oil is displaced by the formation water from the sister-cores for a recovery assessment excluding the ion exchange processes. After re-saturation, oil is displaced by water with alternate salinity. The conditions of large-scale approximation, where the capillary pressure and dispersion effects are negligible, have been achieved in the tests. This allows the derivation of the modified Welge–JBN method to determine relative permeability from the performed tests. The obtained relative permeability curves for water exhibits an abnormal decline at high saturations, which is attributed to fines mobilization and straining yielding the water permeability decline.