High temperature stabilizer for well treatment fluids and methods of using same

Abstract

A method of fracturing a subterranean formation by introducing into the formation a high temperature well treatment fluid containing a polymeric gel and an electron donating compound comprising phenothiazine or a phenothiazine derivative. The high temperature well treatment fluid may further contain a crosslinking agent or the polymeric gel may be crosslinked. The electron donating compound performs as a stabilizer in the treatment of wells having a subterranean formation temperature of up to about 500° F. (260° C.).

1 . A method of fracturing a subterranean formation comprising:
 (a) introducing into the subterranean formation at a pressure sufficient to create fractures a high temperature well treatment fluid comprising a polymeric gel and an electron donating compound comprising phenothiazine or a phenothiazine derivative;   (b) preventing hydrolysis of the polymeric gel by protecting the site of degradation of the polymeric gel with the electron donating compound; and   (c) preventing thermal degradation of the polymeric gel until a temperature of up to about 500° F. (260° C.).   
     
     
         2 . The method of  claim 1 , wherein the high temperature well treatment fluid further contains a crosslinking agent. 
     
     
         3 . The method of  claim 1 , wherein the polymeric gel comprises a crosslinked polymer. 
     
     
         4 . The method of  claim 3 , wherein the polymeric gel comprises a crosslinked polymer derived from a polymer selected from the group consisting of galactomannan gums and their derivatives, glucomannan gums and their derivatives, guar gum, locust bean gum, cara gum, carboxymethyl guar, hydroxyethyl guar, hydroxypropyl guar carboxymethylhydroxyethyl guar, carboxymethylhydroxypropyl guar cellulose, cellulose derivatives, hydroxypropyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, acrylamide, polyvinyl alcohol, a copolymer of acrylamide, and combinations thereof. 
     
     
         5 . The method of  claim 1 , wherein the electron donating compound comprising phenothiazine or phenothiazine derivative is present in a range of about 100 ppm to about 250 ppm of the high temperature well treatment fluid. 
     
     
         6 . The method of  claim 1 , wherein the high temperature well treatment fluid further comprises a pH buffer that maintains a pH of the high temperature well treatment fluid in a range of about 4.5 to about 5.25. 
     
     
         7 . The method of  claim 1 , wherein the phenothiazine or phenothiazine derivative is selected from the group consisting of unsubstituted phenothiazine, unsubstituted phenothiazine 5-oxide derivative, unsubstituted phenothiazine hydrohalogenide derivative, alkyl-substituted phenothiazine, aryl-substituted phenothiazine, aroyl-substituted phenothiazine, carboxyl-substituted phenothiazine, halogen-substituted phenothiazine, N-(dialkylaminoalkyl)-substituted phenothiazine, phenothiazine-5-oxide, alkyl-substituted phenothiazine-5-oxide, aryl-substituted phenothiazine-5-oxide, aroyl-substituted phenothiazine-5-oxide, carboxyl-substituted phenothiazine-5-oxide, halogen-substituted phenothiazine-5-oxide, N-(dialkylaminoalkyl)-substituted phenothiazine-5-oxide, the hydrochlorides of these compounds, or combinations thereof. 
     
     
         8 . The method of  claim 1 , wherein the electron donating compound further comprises sodium thiosulfate. 
     
     
         9 . A method of fracturing a subterranean formation comprising the steps of:
 a) introducing into the formation at a pressure sufficient to create fractures an aqueous high temperature well treatment fluid comprising a polymeric gel and an electron donating compound comprising phenothiazine or a phenothiazine derivative;   b) protecting the site of degradation of the polymeric gel with the electron donating compound; and   c) preventing thermal degradation of the polymeric gel   
       wherein the phenothiazine or phenothiazine derivative is present in the high temperature well treatment fluid in an amount effective to prevent thermal degradation of the polymeric gel until a temperature of up to about 500° F. (260° C.). 
     
     
         10 . The method of  claim 9 , wherein the electron donating compound comprising phenothiazine or phenothiazine derivative is present in a range of about 100 ppm to about 250 ppm of the high temperature well treatment fluid. 
     
     
         11 . The method of  claim 9 , wherein the aqueous high temperature well treatment fluid further comprises a crosslinking agent. 
     
     
         12 . The method of  claim 9 , wherein the polymeric gel comprises a crosslinked polymer derived from a polymer selected from the group consisting of galactomannan gums and their derivatives, glucomannan gums and their derivatives, guar gum, locust bean gum, cara gum, carboxymethyl guar, hydroxyethyl guar, hydroxypropyl guar carboxymethylhydroxyethyl guar, carboxymethylhydroxypropyl guar cellulose, cellulose derivatives, hydroxypropyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, acrylamide, polyvinyl alcohol, a copolymer of acrylamide, and combinations thereof. 
     
     
         13 . The method of  claim 9 , wherein the electron donating compound further comprises sodium thiosulfate. 
     
     
         14 . A method of treating a well comprising the steps of:
 a) introducing into the well an aqueous high temperature well treatment fluid comprising a polymeric gel and an electron donating compound comprising phenothiazine or phenothiazine derivative;   b) protecting the site of degradation of the polymeric gel with the electron donating compound; and   c) preventing thermal degradation of the polymeric gel until a temperature of up to about 500° F. (260° C.).   
     
     
         15 . The method of  claim 14 , wherein the aqueous high temperature well treatment fluid is a drilling mud, a completion fluid or a workover fluid. 
     
     
         16 . The method of  claim 14 , wherein the electron donating compound further comprises sodium thiosulfate. 
     
     
         17 . The method of  claim 14 , wherein the phenothiazine or phenothiazine derivative is solubilized in toluene, a glycol ether or a glycol ester. 
     
     
         18 . The method of  claim 14 , wherein the phenothiazine or phenothiazine derivative is selected from the group consisting of unsubstituted phenothiazine, unsubstituted phenothiazine 5-oxide derivative, unsubstituted phenothiazine hydrohalogenide derivative, alkyl-substituted phenothiazine, aryl-substituted phenothiazine, aroyl-substituted phenothiazine, carboxyl-substituted phenothiazine, halogen-substituted phenothiazine, N-(dialkylaminoalkyl)-substituted phenothiazine, phenothiazine-5-oxide, alkyl-substituted phenothiazine-5-oxide, aryl-substituted phenothiazine-5-oxide, aroyl-substituted phenothiazine-5-oxide, carboxyl-substituted phenothiazine-5-oxide, halogen-substituted phenothiazine-5-oxide, N-(dialkylaminoalkyl)-substituted phenothiazine-5-oxide, the hydrochlorides of these compounds, or combinations thereof. 
     
     
         19 . The method of  claim 14 , wherein the aqueous high temperature well treatment fluid further comprises a crosslinking agent. 
     
     
         20 . The method of  claim 14 , wherein the polymeric gel is a crosslinked polymer.