AN INTERFACIAL-TENSION MODEL FOR MIXED ADSORBED LAYER FOR A TERNARY-SYSTEM - APPLICATION TO AN ACIDIC OIL ALKALI/SURFACTANT SYSTEM/

The variation in interfacial tension in acidic oil-alkaline solution s ystems has been modeled previously. These existing models account for the adsorption of acid, in situ generated surfactant and the added sur factant: at the oil-water interface. However, these models do not acco unt for the interactions that exist between these surfactants in the a dsorbed layer. An existing model for the formation of non-ideal mixed micelles has been modified and extended to a three component mixture t o quantify these interactions. The model is applied to an experimental system consisting of an acidic oil in contact with an alkaline soluti on containing surfactant, Such systems are encountered in the process of chemical enhanced oil recovery. A good agreement is observed betwee n the experimentally measured interfacial tensions and the values pred icted by the present model. The best fit estimates of:he monolayer :in teraction parameters between the acid, surfactant and ionized acid are reported. (C) 1998 Elsevier Science B.V.