TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThis paper identifies chemical cost reduction derived from the synergistic effects of co-surfactant systems using a good foaming agent and a less expensive poor foaming agent. The required good foaming agent is reduced by at least 75%. Also the effect on injectivity is reduced by as much as 50% using the co-surfactant system, compared to a previously used surfactant system. Mobility control of injected CO 2 for improved oil recovery can be achieved with significant reduction in the chemical cost of SAG, improved injectivity of SAG, and improved economics of CO 2 injection project when compared to reported systems.