Method for Enhancing Productivity of Hydrocarbon Formations Using Fluid Containing Organometallic Crosslinking Agent and Scale Inhibitor

Abstract

Scales are prevented or inhibited from forming in a well or in a formation penetrated by a well by pumping into the well a fluid comprising a hydratable polymer, a crosslinking agent, such as an organometallic crosslinking agent containing a polyvalent metal and a scale inhibitor selected from the group consisting of polyvinyl sulfonates, a polyacrylamidomethylpropane sulfonic acid, carboxymethyl inulin and sulfonated polyacrylates and mixtures thereof.

What is claimed is: 
     
         1 . A method of subjecting a hydrocarbon-bearing calcareous or siliceous formation penetrated by a well to a hydraulic fracturing operation which comprises:
 (a) pumping into the well at a pressure sufficient to create or enlarge fractures in the hydrocarbon-bearing calcareous or siliceous formation an aqueous fracturing fluid comprising:
 (i) a crosslinkable viscosifying polymer; 
 (ii) a polyvalent metal containing crosslinking agent; and 
 (iii) a scale inhibitor selected from the group consisting of polyvinyl sulfonates, a polyacrylamidomethylpropane sulfonic acid, 
 carboxymethyl inulin and sulfonated polyacrylates and mixtures thereof 
   
       and creating or enlarging fractures within the hydrocarbon-bearing calcareous or siliceous formation;
 (b) forming a viscous gel containing the scale inhibitor after step (a) by forming crosslinks between the crosslinkable viscosifying polymer and the crosslinking agent wherein the crosslinkable viscosifying polymer forming the crosslinks with the organometallic crosslinking agent consists essentially of a cellulosic derivative, galactomannan gum, carrageenan, polyacrylamide, alkylpolyacrylamide, partially hydrolyzed polyacrylamide or a copolymer of acrylamide and either an acrylate or acrylamidomethylpropane sulfonic acid, starch, polymaleic anhydride, locust bean gum, succinoglycan, scleroglucan, carrageenan, gum Arabic, tara gum, gum ghatti, karaya, tragacanth, pectin, tamarind, polyvinyl alcohol, polypyrrolidone, polysaccharide or derivative containing one or more monosaccharide units of galactose, fructose, mannose, glucoside, glucose, xylose, arabinose, glucuronic acid and pyranosyl sulfate or a mixture thereof and further wherein the viscous gel is stable at a temperature in excess of 150° F. and exhibits a viscosity in excess of 500 cP at 100 sec −1  at 150° F.; 
 (c) transporting the scale inhibitor in the viscous gel into the formation; and 
 (d) preventing and/or inhibiting the formation of scales in the well and/or formation with the transported scale inhibitor during the hydraulic fracturing operation. 
 
     
     
         2 . The method of  claim 1 , wherein the crosslinking agent is an organometallic. 
     
     
         3 . The method of  claim 2 , wherein the polyvalent metal of the organometallic crosslinking agent is selected from the group consisting of Zr, Ti, Al and Sb. 
     
     
         4 . The method of  claim 2 , wherein the viscosifying polymer is selected from the group consisting of a cellulosic derivative, galactomannan gums, carrageenan, polyacrylamides, alkylpolyacrylamides, partially hydrolyzed polyacrylamides or a copolymer of acrylamide and either an acrylate or acrylamidomethylpropane sulfonic acid and mixtures thereof. 
     
     
         5 . The method of  claim 2 , wherein the scale inhibitor is:
 (a) a polyvinyl sulfonate having a number average molecular weight between from about 500 to about 100,000;   (b) polyacrylamidomethylpropane sulfonic acid having a number average molecular weight from about 500 to about 200,000;   (c) carboxymethyl inulin having a number average molecular weight from about 500 to about 30,000;   (d) a sulfonated polyacrylate copolymer having a number average molecular weight between from about 500 to about 30,000 or a mixture thereof.   
     
     
         6 . The method of  claim 2 , wherein the scale inhibitor is:
 (a) polyacrylamidomethylpropane sulfonic acid and further wherein the pH of the fracturing fluid is between from about 3.0 to about 6.0;   (b) a polyvinyl sulfonate and further wherein the pH of the fracturing fluid is between from about 3 to about 6;   (c) carboxymethyl inulin and further wherein the pH of the fracturing fluid is between from about 8 to about 12; or   (d) a sulfonated polyacrylate and further wherein the pH of the fracturing fluid is between from about 8 to about 12.   
     
     
         7 . The method of  claim 1 , wherein the crosslinking agent is an inorganic compound. 
     
     
         8 . The method of  claim 7 , wherein the crosslinking agent is an inorganic oxide or inorganic chloride. 
     
     
         9 . The method of  claim 7 , wherein the crosslinking agent is zirconium, dioxide, titanium dioxide, zirconium chloride, titanium chloride, zirconium oxynitrate, zirconium sulfate, titanium oxynitrate, titanium sulfate, zirconium carbonate or zirconium ammonium carbonate. 
     
     
         10 . The method of  claim 7 , wherein the scale inhibitor is:
 (a) a polyvinyl sulfonate having a number average molecular weight between from about 500 to about 100,000;   (b) polyacrylamidomethylpropane sulfonic acid having a number average molecular weight from about 500 to about 200,000;   (c) carboxymethyl inulin having a number average molecular weight from about 500 to about 30,000;   (d) a sulfonated polyacrylate copolymer having a number average molecular weight between from about 500 to about 30,000 or a mixture thereof.   
     
     
         11 . The method of  claim 7 , wherein the scale inhibitor is:
 (a) polyacrylamidomethylpropane sulfonic acid and further wherein the pH of the fracturing fluid is between from about 3.0 to about 6.0;   (b) a polyvinyl sulfonate and further wherein the pH of the fracturing fluid is between from about 3 to about 6;   (c) carboxymethyl inulin and further wherein the pH of the fracturing fluid is between from about 8 to about 12; or   (d) a sulfonated polyacrylate and further wherein the pH of the fracturing fluid is between from about 8 to about 12.   
     
     
         12 . The method of  claim 7 , wherein the aqueous fracturing fluid further comprises a proppant. 
     
     
         13 . A method of inhibiting or controlling the deposition of scales in a well or in a subterranean formation penetrated by a well during a fracturing operation, the method comprising:
 (a) pumping into the well at a pressure sufficient to create or enlarge a fracture a fracturing fluid, wherein the fracturing fluid comprises:
 (i) a hydratable viscosifying polymer; 
 (ii) a polyvalent metal containing crosslinking agent; and 
 (iii) a scale inhibitor selected from the group consisting of polyvinyl sulfonates, a polyacrylamidomethylpropane sulfonic acid, a carboxymethyl inulin and sulfonated polyacrylates and mixtures thereof; 
   (b) forming a viscous gel from the fracturing fluid containing the scale inhibitor by forming crosslinks between the viscosifying polymer and the crosslinking agent in the presence of the scale inhibitor wherein the viscous gel is stable at a temperature in excess of 150° F. during the fracturing operation and has a viscosity in excess of 500 cP at 100 sec −1  at a temperature in excess of 150° F. and wherein the viscosifying polymer forming the crosslinks consists essentially of a cellulosic derivative, galactomannan gum, carrageenan, polyacrylamide, alkylpolyacrylamide, partially hydrolyzed polyacrylamide or a copolymer of acrylamide and either an acrylate or acrylamidomethylpropane sulfonic acid, starch, polymaleic anhydride, locust bean gum, succinoglycan, scleroglucan, carrageenan, gum Arabic, tara gum, gum ghatti, karaya, tragacanth, pectin, tamarind, polyvinyl alcohol, polypyrrolidone, polysaccharide or derivative containing one or more monosaccharide units of galactose, fructose, mannose, glucoside, glucose, xylose, arabinose, glucuronic acid and pyranosyl sulfate or a mixture thereof; and   (c) transporting the scale inhibitor into a targeted zone of the subterranean formation subjected to the fracturing operation.   
     
     
         14 . The method of  claim 13 , wherein the crosslinkable viscosifying polymer is selected from the group consisting of of a cellulosic derivative, galactomannan gum, carrageenan, polyacrylamide, alkylpolyacrylamide, partially hydrolyzed polyacrylamide or a copolymer of acrylamide and either an acrylate or acrylamidomethylpropane sulfonic acid or a mixture thereof. 
     
     
         15 . The method of  claim 13 , wherein the crosslinking agent is organometallic. 
     
     
         16 . The method of  claim 15 , wherein the polyvalent metal of the organometallic crosslinking agent is Zr, Ti, Al or Sb. 
     
     
         17 . The method of  claim 13 , wherein the crosslinking agent is an inorganic compound. 
     
     
         18 . The method of  claim 17 , wherein the scale inhibitor is:
 (a) a polyvinyl sulfonate having a number average molecular weight between from about 500 to about 100,000;   (b) polyacrylamidomethylpropane sulfonic acid having a number average molecular weight from about 500 to about 200,000;   (c) carboxymethyl inulin having a number average molecular weight from about 500 to about 30,000;   (d) a sulfonated polyacrylate copolymer having a number average molecular weight between from about 500 to about 30,000 or a mixture thereof.   
     
     
         19 . The method of  claim 17 , wherein the aqueous fracturing fluid further comprises a proppant. 
     
     
         20 . A method of subjecting a hydrocarbon-bearing calcareous or siliceous formation penetrated by a well to a hydraulic fracturing operation which comprises:
 (a) pumping into the well at a pressure sufficient to create or enlarge fractures in the hydrocarbon-bearing calcareous or siliceous formation an aqueous fracturing fluid comprising:
 (i) a crosslinkable viscosifying polymer; 
 (ii) an inorganic polyvalent metal containing crosslinking agent; and 
 (iii) a scale inhibitor selected from the group consisting of polyvinyl sulfonates, a polyacrylamidomethylpropane sulfonic acid, carboxymethyl inulin and sulfonated polyacrylates and mixtures thereof 
   
       and creating or enlarging fractures within the hydrocarbon-bearing calcareous or siliceous formation;
 (b) forming a viscous gel containing the scale inhibitor after step (a) by forming crosslinks between the crosslinkable viscosifying polymer and the crosslinking agent wherein the crosslinkable viscosifying polymer forming the crosslinks with the crosslinking agent consists essentially of a cellulosic derivative, a galactomannan gum or a mixture thereof and further wherein the viscous gel is stable at a temperature in excess of 150° F. and exhibits a viscosity in excess of 500 cP at 100 sec −1  at 150° F.; 
 (c) transporting the scale inhibitor in the viscous gel into the formation; and 
 (d) preventing and/or inhibiting the formation of scales in the well and/or formation with the transported scale inhibitor during the hydraulic fracturing operation.