pH tolerant heteropolysaccharide gels for use in profile control

摘要

A pH tolerant aqueous gel-forming composition for placement within a subterranean formation. The composition includes water, a viscosifying amount of a heteropolysaccharide prepared by growing Xanthomonas campestris NCIB 11854 in an aqueous nutrient medium by aerobic fermentation and recovering the heteropolysaccharide, and a crosslinking agent for the heteropolysaccharide in an amount sufficient to cause gelation of the aqueous solution of the Xanthomonas compestris NCIB 11854 heteropolysaccharide. Also described is a two-stage gel-forming composition for use in controlling the profile of a subterranean formation.