Phase behavior and rheology of emulsions in an alkaline/cosolvent/crude oil/brine system

Phase behavior of active crude oil/alkaline was systematically studied in the presence of cosolvents. For this purpose, several factors have been considered: alkaline concentration, oil concentration, and type of brine. The best composition was used to generate emulsion for rheology and displacement tests. Furthermore, precipitation of alkaline was eliminated by its synergy with EDTA. Next, rheology of emulsion was analyzed by which a Power law model was developed that indicates non-Newtonian behavior of emulsion. Moreover, the viscosity of emulsion was reduced by the addition of cosolvent as well as by the increase of alkaline concentration. Finally, the best formulation (containing iso-butanol as cosolvent) in the accompaniment with polymer was prepared to be flooded into a sandpack medium. The result was promising so that approximately 40% of original oil in place could be incrementally recovered.