Method for fracturing subterranean formations

Claim 1

A method for fracturing a subterranean formation comprising: preparing a fracturing fluid by admixing an aqueous liquid, a gelling agent comprising a cellulose ether which is chemically modified to incorporate pendent vicinal dihydroxy groups in an amount sufficient to provide a DS of about 0.3 to about 1.3 and exhibits shear-thermal stability at a temperature in excess of 200° F., said gelling agent being present in an amount in excess of about 0.2 percent by weight of said aqueous liquid and a crosslinking agent present in an amount of at least about 0.001 percent by weight of said aqueous liquid; and introducing said fracturing fluid into a subterranean formation at a rate and pressure sufficient to fracture said formation.

Claim 2

A method for fracturing a subterranean formation comprising: preparing a fracturing fluid by admixing an aqueous liquid, a gelling agent comprising a cellulose ether which is chemically modified to incorporate pendent vicinal dihydroxy groups in an amount sufficient to provide a DS of about 0.3 to about 1.3 and exhibits shear-thermal stability at a temperature in excess of 200° F., said gelling agent being present in an amount in excess of about 0.2 percent by weight of said aqueous liquid and a crosslinking agent present in an amount of at least about 0.001 percent by weight of said aqueous liquid; and introducing said fracturing fluid into a subterranean formation at a rate and pressure sufficient to fracture said formation.

Claim 9

A method of fracturing a subterranean formation penetrate by a well bore comprising: preparing a fracturing fluid by admixing an aqueous liquid, a gelling agent comprising a cellulose ether which is chemically modified to incorporate pendent vicinal dihydroxy groups in an amount sufficient to provide a DS of about 0.3 to about 1.3 and exhibits shear-thermal stability at a temperature in excess of 200° F., said gelling agent being present in an amount in excess of about 0.2 percent by weight of said aqueous liquid and a crosslinking agent present in an amount of at least about 0.001 percent by weight of said aqueous liquid said gelling agent being prepared by charging said cellulose ether to a diluent system including water in an amount sufficient to swell said cellulose ether to provide a slurry in an enclosed reaction vessel, adding an alkaline material in an amount sufficient to catalyze the reaction of said cellulose ether, with a reactant capable of incorporating into said cellulose ether a pendent vicinal dihydroxy structure, adding said reactant over a predetermined period of time in an amount sufficient to react with and incorporate in said cellulose ether said degree of substitution of pendent vicinal dihydroxy structure, maintaining the temperature of said slurry of cellulose ether and said reactant at a temperature in the range of from about ambient to about the reflux temperature of the diluent system during said reaction, adding acid in an amount sufficient to neutralize the modified cellulose ether to form a water soluble cellulose ether product comprising said gelling agent; and introducing said fracturing fluid into a subterranean formation at a rate and pressure sufficient to fracture said formation.

Claim 10

A method of fracturing a subterranean formation penetrate by a well bore comprising: preparing a fracturing fluid by admixing an aqueous liquid, a gelling agent comprising a cellulose ether which is chemically modified to incorporate pendent vicinal dihydroxy groups in an amount sufficient to provide a DS of about 0.3 to about 1.3 and exhibits shear-thermal stability at a temperature in excess of 200° F., said gelling agent being present in an amount in excess of about 0.2 percent by weight of said aqueous liquid and a crosslinking agent present in an amount of at least about 0.001 percent by weight of said aqueous liquid said gelling agent being prepared by charging said cellulose ether to a diluent system including water in an amount sufficient to swell said cellulose ether to provide a slurry in an enclosed reaction vessel, adding an alkaline material in an amount sufficient to catalyze the reaction of said cellulose ether, with a reactant capable of incorporating into said cellulose ether a pendent vicinal dihydroxy structure, adding said reactant over a predetermined period of time in an amount sufficient to react with and incorporate in said cellulose ether said degree of substitution of pendent vicinal dihydroxy structure, maintaining the temperature of said slurry of cellulose ether and said reactant at a temperature in the range of from about ambient to about the reflux temperature of the diluent system during said reaction, adding acid in an amount sufficient to neutralize the modified cellulose ether to form a water soluble cellulose ether product comprising said gelling agent; and introducing said fracturing fluid into a subterranean formation at a rate and pressure sufficient to fracture said formation.