The Effect of Phase Behavior on Recovery Efficiency with Micellar Floods

Abstract

Abstract Phase diagrams were developed for two oils and two combinations of petroleum sulfonate and alcohol to determine whether such diagrams are useful as a screening test for surfactants to be used in micellar flooding. The diagrams illustrate the effects of surfactant concentration, salinity, cosurfactant, calcium, and tripolyphosphate; temperature and pH effects were also examined. Because of the importance of rheological properties in recovery, an aqueous micellar fluid was properties in recovery, an aqueous micellar fluid was studied. Viscosity data were supplemented by conductance measurements to get a better understanding of the colloidal changes taking place. A few laboratory micellar floods showed an encouraging correlation with phase behavior. Introduction Because of the improved economic climate for tertiary oil recovery and the technological promise of micellar flooding, the Bureau of Mines is supporting the development of this technique in laboratory and field tests. Screening tests for micellar fluids are needed to determine the optimum formulation for a particular reservoir. particular reservoir. The term "micellar fluids" here designates emulsions produced by blending petroleum sulfonate, an alcohol as a "cosurfactant," and brines. The term applies to a surfactant at above its critical micelle concentration. There is no sharp boundary between micellar flooding and other types of surfactant flooding. Since the pioneer work of Gogarty, Davis, and coworkers, fluids of higher oil content have been tested in the laboratory and field by Holm and others, and fluids of higher water content have been studied elsewhere. Related work with petroleum sulfonate surfactants has been reported from petroleum sulfonate surfactants has been reported from several laboratories. The various micellar fluids differ in viscosity and homogeneity, and in their response to salinity, temperature, and the presence of divalent ions. It is often assumed that the most effective micellar fluids for tertiary recovery are those that best solubilize crude oil, but this assumption is open to some question. If, however, it can be supported by investigation, it could form the basis for screening tests. This was a major reason for undertaking the present work. present work.