Breaking diutan with metal activitor down to 140 °f or lower

Abstract

A method of gravel packing a treatment zone of a well includes the steps of: (A) forming a treatment fluid including a continuous aqueous phase and gravel, wherein the aqueous phase includes: (i) water; (ii) diutan; (iii) oxidizer in the range of 0.1% to 2% by weight of the water; (iv) organic acid in the range of 0.5% to 5% by weight of the water; and (v) transition metal compound in the range of 0.001% to 0.25% by weight of the water; and (B) introducing the treatment fluid into the treatment zone; wherein the design temperature is less than 180° F.; wherein the continuous phase of the treatment fluid has a viscosity in the range of 10 cP to 75 cP at the design temperature; and wherein the concentration of the organic acid is less than would cause the diutan to salt out at the design temperature.

What is claimed is: 
     
         1 . A method of gravel packing a treatment zone of a well, the method comprising the steps of:
 (A) forming a treatment fluid comprising a continuous aqueous phase and gravel, wherein the continuous aqueous phase comprises:
 (i) water; 
 (ii) a viscosity-increasing agent selected from the group consisting of diutan, clarified diutan, a water-soluble derivative of diutan, and any combination thereof; 
 (iii) a water-soluble oxidizer or source of a water-soluble oxidizer, wherein the concentration of the water-soluble oxidizer is in the range of 0.1% to 2% by weight of the water of the continuous phase; 
 (iv) a water-soluble organic acid or source of a water-soluble organic acid, wherein the water-soluble organic acid has a pKa(1) in the range of 1 to 5 and the concentration of the water-soluble organic acid is in the range of 0.5% to 5% by weight of the water of the continuous phase; and 
 (v) a water-soluble transition metal compound or source of a water-soluble transition metal compound, wherein the concentration of the water-soluble transition metal compound is in the range of 0.001% to 0.25% by weight of the water of the continuous phase; and 
   (B) introducing the treatment fluid into the treatment zone of the well;
 wherein the design temperature of the treatment zone of the well is less than 180° F. (82.2° C.); 
 wherein the continuous phase of the treatment fluid has or develops a viscosity in the range of 10 cP to 75 cP at the design temperature; and 
 wherein the concentration of the water-soluble organic acid is less than the concentration that would cause the viscosity-increasing agent to salt out from the continuous aqueous phase at the design temperature. 
   
     
     
         2 . The method according to  claim 1 , wherein the aqueous phase comprises inorganic salt dissolved in the continuous aqueous phase to the extent of at least 2% by weight of the water. 
     
     
         3 . The method according to  claim 1 , wherein the aqueous phase comprises inorganic salt dissolved in the continuous aqueous phase to the extent of at least 5% by weight of the water. 
     
     
         4 . The method according to  claim 1 , wherein the viscosity-increasing agent is selected from the group consisting of diutan, clarified diutan, and any combination thereof. 
     
     
         5 . The method according to  claim 1 , wherein the viscosity of the treatment fluid is at least 20 cP. 
     
     
         6 . The method according to  claim 1 , wherein the oxidizer comprises a peroxide. 
     
     
         7 . The method according to  claim 6 , wherein the oxidizer comprises t-butyl hydro peroxide. 
     
     
         8 . The method according to  claim 1 , wherein the organic acid is formic acid. 
     
     
         9 . The method according to  claim 1 , wherein the transition metal of the transition metal compound is selected from the group consisting of manganese, vanadium, cobalt, and iron has a valence state of at least 2. 
     
     
         10 . The method according to  claim 1 , wherein the transition metal compound is a ferric compound. 
     
     
         11 . The method according to  claim 1 , wherein the transition metal compound is a ferric chloride. 
     
     
         12 . The method according to  claim 1 , wherein the pH of the continuous aqueous phase of the treatment fluid is in the range of about 3 to about 5. 
     
     
         13 . The method of  claim 1 , wherein the continuous aqueous phase of the treatment fluid further comprises a pH-adjuster other than the viscosity-increasing agent, the oxidizer, the organic acid, and the transition metal compound. 
     
     
         14 . The method according to  claim 13 , wherein the continuous aqueous phase of the treatment fluid excludes a strong acid. 
     
     
         15 . The method according to  claim 1 , wherein the step of introducing comprises introducing under conditions for gravel packing the treatment zone of the wellbore. 
     
     
         16 . The method according to  claim 1 , wherein the step of introducing is below the fracture pressure of the treatment zone of the well. 
     
     
         17 . The method according to  claim 1 , wherein the step of flowing back is in the range of 1 to 5 days of the step of introducing. 
     
     
         18 . The method according to  claim 1 , wherein the design temperature of the treatment zone of the well is between 140° F. (60° C.) and 180° F. (82.2° C.). 
     
     
         19 . A method of gravel packing a treatment zone of a well, the method comprising the steps of: (A) forming a treatment fluid including a continuous aqueous phase and gravel, wherein the aqueous phase comprises: (i) water; (ii) diutan; (iii) oxidizer in the range of 0.1% to 2% by weight of the water; (iv) organic acid in the range of 0.5% to 5% by weight of the water; and (v) transition metal compound in the range of 0.001% to 0.25% by weight of the water; and (B) introducing the treatment fluid into the treatment zone; wherein the design temperature is less than 180° F.; wherein the continuous phase of the treatment fluid has a viscosity in the range of 10 cP to 75 cP at the design temperature; and wherein the concentration of the organic acid is less than would cause the diutan to salt out at the design temperature.