Method of crosslinking cellulose and guar derivatives for treating subterranean formations

摘要

The present invention provides a method of treating of subterranean formation using a gel of a graft copolymer of a hydroxyalkyl cellulose, guar or hydroxypropyl guar prepared by a redox reaction with vinyl phosphonic acid. The gel is formed by hydrating the graft copolymer in an aqueous liquid containing at least a trace amount of at least one divalent cation. The gel is crosslinked by the addition of a Lewis base or Bronsted-Lowry base, which is substantially free of polyvalent metal ions, to the gel in an amount sufficient to effect crosslinking of the graft copolymer.