Surfactant-Polymer Chemical EOR and Subsequent Oil Bank Behaviour

After a waterflood the oil saturation is (close to) the irreducible oil saturation, wherein oil in a porous medium is dispersed over the pore network in unconnected droplets due to snap off. In a chemical flood, the surfactant reduces oil-water interfacial tension and liberates the trapped oil droplets. These mobilised droplets coalesce into a greater body of oil, the oil bank. The surfactant-polymer and polymer slugs, with relatively high viscosity, act as displacing agents with piston-like displacement in an ideal scenario. In this study, these oil banks are studied in core flood experiments using Fontainebleau sandstone cores of varying lengths and one 1m Bentheimer Sandstone core. In these core floods the effects of certain parameters on the oil bank behaviour are examined. The parameters range from rock properties such as permeability and core length, to fluid properties such as optimality of the surfactant to viscosity of the surfactant-polymer and polymer.Petroleum Engineering and Geo-science