compositions and process for recovering of oil from subterranean oil - bearing reservoirs consisting of green non - toxic biodegradable strong alkali metal salt of polymerized weak acids , one or more surfactants , an aqueous fluid , a optionally one or more mobility control agents and optionally one or more co - solvents are disclosed . such compositions are injected into the reservoir through one or more injection wells and assist in recovering trapped oil through one or more producing wells . a preferred green non - toxic biodegradable strong alkali metal salt of polymerized weak acids is the sodium salt of polyaspartic acid shown below where n is 10 to 50 . the compositions and the process of the present invention offer the advantage of improved compatibility with unsoftened waters , surfactants , and various mobility control agents . the green non - toxic , biodegradable properties of the alkali makes it particularly suitable for environmentally sensitive applications such as offshore and inland lakes .