Improving chemical flood efficiency with micellar/alkaline/polymer processes

A laboratory study was undertaken to find more efficient, lower-cost chemical systems for the recovery of waterflood residual oil. The authors' investigation emphasized alkaline-augmented processes because alkali is much less expensive than surfactant. The strategy was to replace some of or all the high-cost surfactants in a micellar formulation with lower-cost alkali and still maintain the high tertiary oil recoveries obtained with micellar flooding. Baseline oil recoveries in Berea corefloods were determined for two interfacially active crude oils with micellar/polymer (MP) and alkaline/polymer (AP) systems. A combination process was then developed in which a small micellar slug is injected first, followed by a larger AP slug. This process is referred to as a micellar/alkaline/polymer (MAP) flood. Phase-behavior studies guided the design and optimization of all three chemical processes in the coreflood experiments. Detailed effluent analyses and in-situ mobility measurements provided information about possible oil recovery mechanisms.