Terpolymer of N-vinyl pyrrolidone in alkoxylated form

摘要

The production of hydrocarbons from a subterranean hydrocarbon-bearing formation containing acid-soluble components, such as one composed at least in part of dolomite or limestone, is stimulated by injecting into the formation usually via casing and cement pack perforations a composition comprising an aqueous solution of a mineral acid having dissolved therein a small amount of a vinylpyrrolidone polymer or an alkoxylated vinylpyrrolidone polymer. The increase in the permeability and porosity of the formation achieved utilizing the method of invention results in a substantial improvement in hydrocarbon recovery. Optionally, the injected composition may be saturated with natural gas at the injection pressure. In another embodiment this invention relates to the oxyalkylated vinylpyrrolidone polymer compositions.