The Influence of Interfacial Properties on Immiscible Displacement Behavior

In order to obtain better understanding of displacement mechanisms of importance to oil recovery, a technique has been developed to study the immiscible displacement of a liquid/fluid system in capillaries of model geometry. Called the Interfacial Displacement Tensiometer, this technique enables measurement of the pressure changes accompanying displacement of a single interface. The effects of discrete events, such as changes in pore geometry, can therefore be determined. From the pressure measurements, together with determination of the wettability, dynamic interfacial tensions can be calculated. The results presented are for a range of pure oil/aqueous phase systems; in particular effects due to the presence of water soluble and oil soluble surfactants are examined. The results demonstrate that the surfactant systems possess high (dynamic) interfacial tensions during displacement, and the factors controlling their values are discussed. In addition, it is demonstrated that highly visco-elastic interfacial films can contribute an additional resistance to displacement.