Compositions and methods for breaking a viscosity increasing polymer at very low temperature used in downhole well applications

Abstract

A composition for treating a portion of a wellbore or a portion of a subterranean formation is provided, the composition comprising: (a) water; (b) a source of hydrogen peroxide, and (c) an activator for the source of hydrogen peroxide; wherein the pH of the composition is adjusted to be within an appropriate range for the type of activator. A method for treating a portion of a wellbore or a portion of a subterranean formation, the method comprising the steps of: forming or providing a composition comprising: (a) water; (b) a source of hydrogen peroxide, and (c) an activator for the source of hydrogen peroxide; wherein the pH of the composition is adjusted within an appropriate range for the type of activator; and introducing the composition through a wellbore to treat a portion of a wellbore or a portion of a subterranean formation. The activator can be a water-soluble alkanoyl-donor compound or a chelated transition metal. Preferably, the composition further comprises an iron chelating agent. The composition and method are adapted for breaking a viscosity increasing polymer, such as xanthan. The method has particular applications where the static temperature of the portion of the wellbore or the portion of the subterranean formation to be treated is less than 100° F. (38° C.).

1 . A composition for treating a portion of a wellbore or a portion of a subterranean formation, the composition comprising:
 (a) water;   (b) a source of hydrogen peroxide, and   (c) an activator selected from the group consisting of a chelated transition metal, a chelating agent and a transition metal, and any combination thereof in any proportion;   wherein the pH of the composition is adjusted in the range of 3 to 10.   
     
     
         2 . The composition according to  claim 1 , wherein the transition metal is selected from the group consisting of: copper, cobalt, manganese, iron, and any combination thereof in any proportion. 
     
     
         3 . The composition according to  claim 1 , wherein the chelating agent comprises: EDTA, alkali or alkaline metal salt of EDTA, alkali metal citrate, citric acid, iminodiacetic acid, gluconate, NTA, tetraamidomacrocyclic ligand, and any combination thereof in any proportion. 
     
     
         4 . The composition according to  claim 1 , wherein the chelated transition metal is selected from the group consisting of: as copper-EDTA, Fe-citrate, Mn(III)-gluconate, Fe-Tetraamidomacrocyclic ligand, and any combination thereof in any proportion. 
     
     
         5 . The composition according to  claim 1 , further comprising: a pH adjusting compound for adjusting the pH of the composition. 
     
     
         6 . The composition according to  claim 1 , further comprising a viscosity increasing polymer. 
     
     
         7 - 22 . (canceled) 
     
     
         23 . The method according to  claim 6 , wherein the viscosity increasing polymer is selected from the group consisting of: xanthan, diutan, and succinoglycan gums. 
     
     
         24 . The method according to  claim 6 , wherein the viscosity increasing polymer comprises xanthan. 
     
     
         25 . The composition according to  claim 1 , wherein the source of hydrogen peroxide is selected from the group consisting of inorganic persalts, alkali metal peroxides (e.g. sodium peroxide), organic peroxide (e.g. urea-hydrogen peroxide), and hydrogen peroxide, and any combination thereof in any proportion. 
     
     
         26 . The composition according to  claim 1 , wherein the source of hydrogen peroxide is an inorganic persalt selected from the group consisting of alkali perborates, percarbonates, and perphosphates. 
     
     
         27 . The composition according to  claim 1 , wherein the source of hydrogen peroxide is an inorganic persalt selected from the group consisting of sodium perborate monohydrate, sodium perborate tetrahydrate, sodium percarbonate, and sodium pyrophosphate peroxyhydrate. 
     
     
         28 . The method according to  claim 1 , wherein the composition further comprises: sand, gravel, resin-coated proppant, or synthetic proppant. 
     
     
         29 . A composition for treating a portion of a wellbore or a portion of a subterranean formation, the composition comprising:
 (a) water;   (b) a viscosity increasing polymer selected from the group consisting of: xanthan, diutan, and succinoglycan gums;   (c) a source of hydrogen peroxide, and   (d) an activator selected from the group consisting of a chelated transition metal, a chelating agent and a transition metal, and any combination thereof in any proportion;   (e) a buffering agent selected to help maintain the pH of the composition in any range within a range of 3 to 10.   
     
     
         30 . The composition according to  claim 29 , wherein the transition metal is selected from the group consisting of: copper, cobalt, manganese, iron, and any combination thereof in any proportion. 
     
     
         31 . The composition according to  claim 29 , wherein the chelating agent comprises: EDTA, alkali or alkaline metal salt of EDTA, alkali metal citrate, citric acid, iminodiacetic acid, gluconate, NTA, tetraamidomacrocyclic ligand, and any combination thereof in any proportion. 
     
     
         32 . The composition according to  claim 29 , wherein the chelated transition metal is selected from the group consisting of: as copper-EDTA, Fe-citrate, Mn(III)-gluconate, Fe-Tetraamidomacrocyclic ligand, and any combination thereof in any proportion. 
     
     
         33 . A composition for treating a portion of a wellbore or a portion of a subterranean formation, the composition comprising:
 (a) water;   (b) a xanthan polymer;   (c) a perborate; and   (d) an activator selected from the group consisting of a chelated transition metal, a chelating agent and a transition metal, and any combination thereof in any proportion;   (e) a buffering agent selected to help maintain the pH of the composition in any range within a range of 3 to 10.   
     
     
         34 . The composition according to  claim 33 , wherein the transition metal is selected from the group consisting of: copper, cobalt, manganese, iron, and any combination thereof in any proportion. 
     
     
         35 . The composition according to  claim 33 , wherein the chelating agent comprises: EDTA, alkali or alkaline metal salt of EDTA, alkali metal citrate, citric acid, iminodiacetic acid, gluconate, NTA, tetraamidomacrocyclic ligand, and any combination thereof in any proportion. 
     
     
         36 . The composition according to  claim 33 , wherein the chelated transition metal is selected from the group consisting of: as copper-EDTA, Fe-citrate, Mn(III)-gluconate, Fe-Tetraamidomacrocyclic ligand, and any combination thereof in any proportion.