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

Displacement of oil from unconsolidated porous media was investigated. Waterflooding and alkaline flooding tests were conducted in model porous media consisting of fine glass beads wet-packed into a cylindrical holder. Mixtures 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 waterflooding decreased as oil viscosity increased. Addition of acid to the oil reduced the waterflooding recovery by more than 20% for all oils. Alkaline flooding of after-waterflood residual oil produced incremental recovery only in the case of the least viscous oil (20 mPa s). The incremental recovery increased with the concentration of alkali only up to 25 mmol/l and remained constant thereafter.