High Temperature Crosslinked Fracturing Fluids

Abstract

A fracturing fluid including a mixture of an aqueous copolymer composition including a copolymer, the copolymer having 2-acrylamido-2-methylpropanesulfonic acid, acrylamide, and acrylic acid monomer units, or a salt thereof, and a crosslinker. The crosslinker includes a metal, and the weight ratio of the metal to the copolymer is in a range of 0.01 to 0.08. Treating a subterranean formation includes introducing the fracturing fluid into a subterranean formation, and crosslinking the fracturing fluid in the subterranean formation to yield a crosslinked fracturing fluid. The crosslinked fracturing fluid has a viscosity of at least 500 cP for at least 80 minutes when the gel is subjected to a shear rate of 40 s −1 at a temperature in a range of 300° F. to 400° F.

1 - 21 . (canceled) 
     
     
         22 . A method of treating a subterranean formation, the method comprising:
 introducing a fracturing fluid into a subterranean formation, the fracturing fluid comprising:
 an aqueous copolymer composition comprising a copolymer, the copolymer comprising 2-acrylamido-2-methylpropane-sulfonic acid, acrylamide, and acrylic acid monomer units, or a salt thereof, wherein the copolymer comprises 1 mol % to 40 mol % of the 2-acrylamido-2-methylpropanesulfonic acid monomer units; and 
 a crosslinker comprising a metal, 
 wherein a weight ratio of the metal to the copolymer is in a range of 0.02 to 0.06; 
   wherein the fracturing fluid comprises 20 to 50 pounds of the copolymer per thousand gallons of the fracturing fluid; and   crosslinking the fracturing fluid in the subterranean formation to yield a crosslinked fracturing fluid,   wherein the crosslinked fracturing fluid comprises a viscosity breaker, and the crosslinked fracturing fluid maintains a viscosity of at least 500 cP for up to 180 minutes and has a viscosity of less than 10 cP after 360 minutes when the crosslinked fracturing fluid is subjected to a shear rate of 40 s −1  at a temperature of 300° F.   
     
     
         23 . The method of  claim 22 , wherein a concentration of the metal in the fracturing fluid is in a range of 0.001 wt % to 0.024 wt %. 
     
     
         24 . The method of  claim 22 , wherein the weight ratio of the metal to the copolymer is in a range of 0.02 to 0.04. 
     
     
         25 . The method of  claim 22 , wherein the copolymer comprises 25 mol % of the 2-acrylamido-2-methylpropanesulfonic acid monomer units. 
     
     
         26 . The method of  claim 22 , wherein the copolymer comprises 15 mol % of the -acrylamido-2-methylpropanesulfonic acid monomer units. 
     
     
         27 . The method of  claim 22 , wherein the fracturing fluid comprises at least one of a gel stabilizer, a clay stabilizer, a viscosity breaker, a proppant, and a pH adjusting agent. 
     
     
         28 . The method of  claim 27 , wherein the fracturing fluid comprises the pH adjusting agent and the pH of the fracturing fluid is in a range of 2 to 7. 
     
     
         29 . The method of  claim 28 , wherein pH of the fracturing fluid is in a range of 5 to 7. 
     
     
         30 . The method of  claim 28 , wherein pH of the fracturing fluid is in a range of 5.5 to 6.5. 
     
     
         31 . The method of  claim 22 , wherein the crosslinker comprises zirconium. 
     
     
         32 . The method of  claim 22 , wherein the fracturing fluid comprises 20 to 30 pounds of the copolymer per thousand gallons of the fracturing fluid. 
     
     
         33 . The method of  claim 32 , wherein the fracturing fluid comprises 20 pounds of the copolymer per thousand gallons of the fracturing fluid. 
     
     
         34 . The method of  claim 32 , wherein the fracturing fluid comprises 25 pounds of the copolymer per thousand gallons of the fracturing fluid. 
     
     
         35 . The method of  claim 32 , wherein the fracturing fluid comprises 30 pounds of the copolymer per thousand gallons of the fracturing fluid. 
     
     
         36 . The method of  claim 22 , wherein the viscosity breaker comprises sodium bromate. 
     
     
         37 . The method of  claim 22 , wherein the fracturing fluid comprises between 50 mg/L and 50,000 mg/L of total dissolved solids. 
     
     
         38 . The method of  claim 22 , wherein the crosslinker comprises zirconium, the fracturing fluid comprises 25 pounds of the copolymer per thousand gallons of the fracturing fluid, a weight ratio of the zirconium to the copolymer is in a range of about 0.02 to about 0.06, the copolymer comprises 15 wt % of the 2-acrylamido-2-methylpropane-sulfonic acid monomer units, and the crosslinked fracturing fluid maintains a viscosity of at least 500 cP for up to 180 minutes when the crosslinked fracturing fluid is subjected to a shear rate of 40 s −1  at a temperature of 300° F. 
     
     
         39 . The method of  claim 22 , wherein the crosslinker comprises zirconium, the fracturing fluid comprises 20 pounds of the copolymer per thousand gallons of the fracturing fluid, a weight ratio of the zirconium to the copolymer is in a range of about 0.02 to about 0.06, and the crosslinked fracturing fluid maintains a viscosity of at least 500 cP for up to 180 minutes when the crosslinked fracturing fluid is subjected to a shear rate of 40 s −1  at a temperature of 300° F. 
     
     
         40 . The method of  claim 22 , wherein the crosslinker comprises zirconium, the fracturing fluid comprises 30 pounds of the copolymer per thousand gallons of the fracturing fluid, a weight ratio of the zirconium to the copolymer is in a range of about 0.02 to about 0.04, and the crosslinked fracturing fluid maintains a viscosity of at least 500 cP for up to 80 minutes when the crosslinked.