Well treatment fluids containing biodegradable zirconium crosslinker and methods of using the same

Abstract

A fracturing fluid containing a hydratable viscosifying polymer and a zirconium acetylacetonate crosslinker provides a green alternative to conventional systems. The zirconium aceylacetonate is dissolved in benzyl alcohol or in a mixture of benzyl alcohol and 2,2-dimethyl-1,3-dioxolan-4(yl)-methanol. The pH of the fracturing fluid may be between from about 3.5 to about 11.5. The fracturing fluid may contain an acidic buffering agent or a basic buffering agent. The fracturing fluid may be pumped into a well in order to initiate or enlarge a fracture within a subterranean formation penetrated by the well.

What is claimed is: 
     
         1 . A well treatment fluid comprising:
 a. a zirconium acetylacetonate crosslinker dissolved in a solvent of benzyl alcohol; and   b. a hydratable polymer capable of gelling in the presence of a zirconium acetylacetonate crosslinking agent.   
     
     
         2 . The well treatment fluid of  claim 1 , wherein the pH of the fluid is between from about 3.5 to about 11.5. 
     
     
         3 . The well treatment of  claim 2 , wherein the pH of the fluid is between from about 8.0 to about 11.0. 
     
     
         4 . The well treatment fluid of  claim 3 , further comprising an enzyme breaker. 
     
     
         5 . The well treatment fluid of  claim 2 , wherein the pH of the fluid is between from about 4.0 to about 6.5. 
     
     
         6 . The well treatment fluid of  claim 1 , wherein the amount of zirconium acetylacetonate dissolved in the benzyl alcohol solvent is from about 6 to about 20 percent by weight. 
     
     
         7 . The well treatment fluid of  claim 1 , wherein the hydratable polymer is a synthetic or natural polymer and contains one or more functional groups selected from the group consisting of hydroxyl, carboxyl, sulfate, sulfonate, amino and amido. 
     
     
         8 . The well treatment fluid of  claim 1 , wherein the hydratable polymer is selected from the group consisting of guar gum, guar gum derivatives, locust bean gum, karaya gum, a cellulosic derivative, polyvinyl alcohol, poly 2-amino-2-methyl propane sulfonic acid, polyacrylamide, partially hydrolyzed polyacrylamide and copolymers containing acrylamide, polymers and copolymers of acrylamidomethylpropane sulfonic acid (AMPS) and salts thereof, phosphinated maleic copolymer (PHOS/MA); and combinations thereof. 
     
     
         9 . The well treatment fluid of  claim 1 , wherein the hydratable polymer is selected from the group consisting of guar gum, guar gum derivatives, cellulosic derivatives, polyacrylates, polypyrrolidones, tara, xanthan, succinoglycan, scleroglucan, carrageenan, poly 2-amino-2-methyl propane sulfonic acid, homo- and co-polymers of acrylamide, partially hydrolyzed polyacrylamide, polymers of acrylamidomethylpropane sulfonic acid (AMPS), salts of acrylamido-methyl propane sulfonate/acrylic acid copolymer (AMPS/AA), phosphinated maleic copolymer (PHOS/MA), salts of polymaleic acid/acrylic acid/acrylamido-methyl propane sulfonate terpolymers (PMA/AMPS), copolymers derived from acrylamide, acrylamidomethylpropanesulfonic acid, and vinyl phosphonate, and combinations thereof. 
     
     
         10 . The well treatment fluid of  claim 1 , wherein the hydratable polymer is a polysaccharide or a derivative thereof or a copolymer of at least one monomer of an acrylamide unit and a quaternary ammonium salt group, and, optionally an acrylate and/or nitrogen heterocyclic monomer. 
     
     
         11 . The well treatment fluid of  claim 1 , wherein the hydratable polymer is a underivatized guar, hydroxyalkylated guar, a carboxyalkyl guar, carboxyalkylhydroxyalkyl guar, hydroxyalkyl cellulose, alkylhydroxyalkyl cellulose, a carboxyalkyl cellulose derivative or a mixture thereof. 
     
     
         12 . The well treatment fluid of  claim 11 , wherein the hydratable polymer is selected from the group consisting of underivatized guar, hydroxypropyl guar, carboxymethyl guar, carboxymethylhydroxypropyl guar). carboxymethyl cellulose, carboxymethylhydroxyethyl cellulose, hydroxyethyl cellulose. 
     
     
         13 . The well treatment fluid of  claim 1 , wherein the amount of dissolved crosslinking agent in the fluid is from about 1.5 to about 150 pounds per 1,000 gallons of water. 
     
     
         14 . The well treatment fluid of  claim 1 , wherein the amount of hydratable polymer in the aqueous fluid is between from about 15 to about 50 pounds per 1,000 gallons of water. 
     
     
         15 . The well treatment fluid of  claim 1 , wherein the solvent further comprises 2,2-dimethyl-1,3-dioxolan-4(yl)-methanol. 
     
     
         16 . The well treatment fluid of  claim 15 , wherein the volume ratio of benzyl alcohol:2,2-dimethyl-1,3-dioxolan-4(yl)-methanol is between from about 10:90 to 90:10 
     
     
         17 . The well treatment fluid of  claim 1 , wherein the fluid is a foamed fluid. 
     
     
         18 . The well treatment fluid of  claim 1 , wherein the fluid further comprises nitrogen or carbon dioxide. 
     
     
         19 . A well treatment fluid comprising:
 (a) a crosslinking solution comprising zirconium acetylacetonate dissolved in a solvent of benzyl alcohol; and   (b) a hydratable polymer selected from the group consisting of guar gum, guar gum derivatives, cellulosic derivatives, polyacrylates, polypyrrolidones, tara, xanthan, succinoglycan, scleroglucan, carrageenan, polyvinyl alcohol, poly 2-amino-2-methyl propane sulfonic acid, polyacrylamide, partially hydrolyzed polyacrylamide and copolymers containing acrylamide, polymers and copolymers of acrylamidomethylpropane sulfonic acid (AMPS) and salts thereof, phosphinated maleic copolymer (PHOS/MA); and combinations thereof.   wherein:   (i) the amount of zirconium acetylacetonate dissolved in the benzyl alcohol solvent is from 6 to 20 percent by weight;   (a) the amount of dissolved crosslinking agent is from about 1.5 to about 150 pounds per 1,000 gallons of water in the fluid; and   (b) the amount of hydratable polymer in the aqueous fluid is between from about 15 to about 50 pounds per 1,000 gallons of water in the fluid.   
     
     
         20 . A well treatment fluid comprising:
 (a) a crosslinking solution comprising zirconium acetylacetonate dissolved in a solvent consisting essentially of either benzyl alcohol or a mixture of benzyl alcohol and 2,2-dimethyl-1,3-dioxolan-4(yl)-methanol; and   (b) a hydratable polymer capable of gelling in the presence of the zirconium acetylacetonate.