Lithium salts as additives in petroleum recovery processes

In a surfactant flooding process for recovering petroleum from a subterranean petroleum reservoir wherein the reservoir is penetrated by at least one injection well and at least one production well, said wells being in fluid communication with said formation, wherein the process comprises the steps of injecting an aqueous surfactant solution through the injection well into the reservoir, forcing the surfactant solution through the reservoir and recovering petroleum from the production well, the improvement for reducing the amount of surfactant retained by the formation comprising:

• injecting into the reservoir, prior to the injection of the aqueous surfactant solution, an aqueous solution containing an amount of lithium chloride effective for reducing surfactant retention by the formation.