Enhanced oil recovery profile control with crosslinked anionic acrylamide copolymer gels

摘要

An aqueous polymeric gel-forming composition capable of selectively plugging highly permeable zones in subterranean oil-bearing formations. The composition comprises an aqueous solution of an anionic acrylamide copolymer of high molecular weight, comprising about 5 to 95 weight percent of 2-acrylamido-2-methylpropanesulfonic acid, about 2 to 95 weight percent of N-vinyl-N-methyl acetamide and about 5 to 93 weight percent of acrylamide, and a crosslinking agent selected from the group consisting of transition metal ions, phenolic resins and amino resins. The compositions of this invention will form stable gels in brines of wide-ranging salinity and are effective at the pH levels encountered in carbon dioxide and water flooding operations. Also provided is a process for selectively plugging regions of higher permeability within an oil- bearing formation to improve sweep efficiency during a fluid flood oil recovery operation.