September 2012
Features
Mobility and conformance control for carbon dioxide EOR–Part 4
Carbon dioxide foam floods are typically conducted via the alternate injection of aqueous surfactant solution slugs and pure CO2 (SAG). The notion of adding surfactant to CO2 for conformance and/or mobility control was suggested decades ago. Recent developments in the identification and design of CO2-soluble surfactants that generate foams via core studies have re-kindled interest in this idea.1,2 Because oil-bearing formations initially contained brine, and decades of waterflooding have added additional fluids, the need for alternating slugs of an aqueous solution can be reduced or possibly eliminated. Further, the dissolution of surfactant in CO2 helps to ensure that surfactant will be available for in-situ foam generation in areas where the CO2 is flowing.
