A study of branched alcohol propoxylate sulfate surfactants for improved oil recovery

This investigation considers one class of anionic surfactant, a series of branched alcohol propoxylate sulfate surfactants, as candidates for chemical EOR applications. This experimental results show that these surfactants may be preferred candidates for EOR as they can be effective at creating low interfacial tension (IFT) at dilute concentrations, and without requiring an alkaline agent or cosurfactant. In addition, some of the formulations exhibit a low IFT at several percent sodium chloride concentrations, and hence may be suitable for use in more saline reservoirs. Adsorption tests onto kaolinite clay indicate that the loss of these surfactants can be comparable to or greater than other types of anionic surfactants. Surfactant performance was evaluated in oil recovery core flooding tests. Selected formulations could displace most of the waterflood residual oil in place even with dilute, 0.2 wt% surfactant solutions from Berea sandstone cores.