Immiscible fluid displacement in a porous media: Effect of surfactants introduced ab initio versus surfactants formed in-situ

Experiments were performed to study the immiscible displacement of oil from a capillary tube using an aqueous phase fluid. One set of experiments were performed where surfactant was introduced into the aqueous phase liquid at concentrations below the critical micellar concentration prior to displacement, i.e. ab initio. In a second set of experiments surfactant was formed at the interface in-situ via a saponification chemical reaction. For both experiment conditions we measured surface tension using the pendant drop method to estimate adsorption and desorption Biot numbers for the ab initio case; whereas for surfactant produced via chemical reaction this data provided an estimate for rates of change in surface tension that were used to estimate a Damkohler number. The results suggest that surfactants created via saponification reaction tend to have an effect on the interface and film thickness that is entirely absent in non-reactive immiscible displacement experiments.