Composition of aqueous surfactant and liquid or dense phase co.sub.2 for plugging subterranean formations

Abstract From the Canadian patent

Permeable portions of a subterranean formation are temporarily plugged by driving a foam formed by interacting an aqueous surfactant solution and dense fluid carbon dioxide into the permeable portions of the formation. In an embodiment of the invention the aqueous surfactant solution and the dense fluid carbon dioxide are introduced into the formation by sequential slug injections of the foam generating compositions. In another embodiment oil is displaced from an oil-bearing underground formation by plugging more permeable portions of the formation as described above, introducing a drive fluid into the formation and producing recovered oil and drive fluid from a well penetrating the …