Effects of oil viscosity and interfacial reaction on the displacement of oil from porous media

Displacement of oil from unconsolidated porous media was investigated. Wate rflooding and alkaline flooding tests were conducted in model porous media consisting of fine glass beads wet-packed into a cylindrical holder. Mixtur es of light and heavy paraffin oil of viscosity ranging from 20 to 70 mPa s were used as the oil phase. Acidic oil was simulated by dissolving 10 mmol /l of linoleic acid in the oil. As expected, recovery of neutral oil by wat erflooding decreased as oil viscosity increased. Addition of acid to the oi l reduced the waterflooding recovery by more than 20% for all oils. Alkalin e flooding of after-waterflood residual oil produced incremental recovery o nly in the case of the least viscous oil (20 mPa s). The incremental recove ry increased with the concentration of alkali only up to 25 mmol/l and rema ined constant thereafter.