US Patent 7732382 Cross-linking composition and method of use

A cross-linking composition comprises (a) an aqueous liquid, (b) a pH buffer, (c) a cross-linkable organic polymer, (d) a cross-linking agent which comprises an organic titanate, an organic zirconate, or combinations thereof, and (e) a delay agent which is a hydroxyalkylaminocarboxylic acid. The composition provides flexibility in rate of cross-linking and can be used over a wide range of pH. Further disclosed are methods to use the composition in oil field applications for hydraulic fracturing and plugging of permeable zones and leaks in subterranean formations.