Conformance improvement in hydrocarbon bearing underground strata using lignosulfonate-acrylic acid graft copolymer gels

A method for reducing the permeability of a subterranean formation, the method comprising:

• preparing a gelant solution including an aqueous solvent, about 2% to about 16% by weight of a lignosulfonate-acrylic acid graft copolymer and a sufficient concentration of a crosslinking agent to crosslink the copolymer, the copolymer having an acrylic acid content of about 10% to about 50% by weight, and wherein the crosslinking agent is a complex of one or more positively charged chromium (III) species and one or more negatively charged carboxylate species,
• injecting the gelant solution into the subterranean formation, and
• crosslinking the gelant solution to form a crosslinked gel.

A method for reducing the permeability of a region of an underground formation, the method comprising:

• predetermining the characteristics of the region,
• providing a gelant solution capable of forming a crosslinked gel within the region, the crosslinked gel having predetermined gel properties, wherein the gelant solution comprises an aqueous solvent, about 2% to about 16% by weight of a lignosulfonate-acrylic acid graft copolymer and a sufficient concentration of a crosslinking agent to crosslink the copolymer, the copolymer having an acrylic acid content of about 10% to about 50% by weight, and wherein the crosslinking agent is a complex of one or more positively charged chromium (III) species and one or more negatively charged carboxylate species, and
• injecting the gelant solution into the region.