Composition Useful in Sulfate Scale Removal

Abstract

The present invention discloses a novel aqueous composition for use in removing mixed sulfate scale from a surface contaminated with such, said composition comprising: a chelating agent and a counterion component selected from the group consisting of: Li5DTPA; Na5DTPA; K5DTPA; Cs5DTPA; Na4EDTA; K4EDTA; TEAH4DTPA; and TBAH5DTPA; a dissolution enhancer; optionally a compound such as sodium gluconate or the like and a carboxyl-containing fructan such as carboxymethyl inulin. There is also disclosed methods to use such compositions.

1 . A method of removing mixed sulfate scale, said method comprising:
 providing a liquid composition comprising:
 a chelating agent selected from the group consisting of: Li 5 DTPA; Na 5 DTPA; K 5 DTPA; Cs 5 DTPA; Na 4 EDTA; K 4 EDTA; TEAH 4 DTPA; and TBAH 5 DTPA; 
 optionally, a scale removal enhancer; 
 a carboxyl-containing fructan; and 
 a compound selected from the group consisting of: sodium gluconate; gluconic acid; glucono-delta-lactone; sodium gluconate; calcium gluconate; potassium gluconate; 
   exposing a surface contaminated with said mixed sulfate scale to the liquid composition; and   allowing sufficient time of exposure to remove said mixed sulfate scale from the contaminated surface.   
     
     
         2 . The method according to  claim 1 , wherein the scale removal enhancer is selected from the group consisting of: potassium carbonate; potassium formate; cesium formate; cesium carbonate; and combinations thereof. 
     
     
         3 . The method according to  claim 3 , wherein the carboxyl-containing fructan is carboxymethylinulin (CMI). 
     
     
         4 . An aqueous composition for use in removing mixed sulfate scale from a surface contaminated with such, said composition comprising:
 a chelating agent and a counterion component selected from the group consisting of: Li 5 DTPA; Na 5 DTPA; K 5 DTPA; Cs 5 DTPA; Na 4 EDTA; K 4 EDTA; TEAH 4 DTPA; and TBAH 5 DTPA;   optionally, a scale removal enhancer;   carboxyl-containing fructan; and   a compound selected from the group consisting of: sodium gluconate; gluconic acid; glucono-delta-lactone; sodium gluconate; calcium gluconate; potassium gluconate.   
     
     
         5 . The aqueous composition according to  claim 4 , wherein the scale removal enhancer is selected from the group consisting of: potassium carbonate; potassium formate; cesium formate and cesium carbonate and combinations thereof. 
     
     
         6 . The aqueous composition according to  claim 4 , wherein the scale removal enhancer is present in the composition in an amount ranging from 5 to 20% wt of the weight of the composition. 
     
     
         7 . The aqueous composition according to  claim 4 , wherein the scale removal enhancer is present in the composition in an amount ranging from 10 to 15% wt of the weight of the composition. 
     
     
         8 . The aqueous composition according to  claim 4 , wherein the scale removal enhancer is present in the composition in an amount of approximately 10 wt % of the weight of the composition. 
     
     
         9 . The aqueous composition according to  claim 4 , wherein the chelating agent and counterion are present in the composition in an amount ranging from 5 to 40 wt % of the weight of the composition. 
     
     
         10 . The aqueous composition according to  claim 4 , wherein the chelating agent and counterion are present in the composition in an amount ranging from 10 to 30 wt % of the weight of the composition. 
     
     
         11 . The aqueous composition according to  claim 4 , wherein the chelating agent and counterion are present in the composition in an amount ranging from 10 to 20 wt % of the weight of the composition. 
     
     
         12 . The aqueous composition according to  claim 4 , wherein the pH of the composition ranges from 10 to 11. 
     
     
         13 . The aqueous composition according to  claim 4 , wherein the scale removal enhancer is selected from the group consisting of: K 5 DTPA; Cs 5 DTPA; Na 4 EDTA; and K 4 EDTA. 
     
     
         14 . The aqueous composition according to  claim 4 , wherein the carboxymethyl inulin is present in the composition in an amount ranging from 0.5 to 15% wt of the weight of the composition. 
     
     
         15 . The aqueous composition according to  claim 4 , wherein the sodium gluconate is present in the composition in an amount ranging from 1% to 20% wt of the weight of the composition. 
     
     
         16 . A method of solubilizing barium sulfate into particles of less than 1 micron in size, said method comprising:
 providing a surface contaminated with a scale containing barium sulfate;   providing a liquid composition comprising:
 a chelating agent selected from the group consisting of: Li 5 DTPA; Na 5 DTPA; K 5 DTPA; Cs 5 DTPA; Na 4 EDTA; K 4 EDTA; TEAH 4 DTPA; and TBAH 5 DTPA; 
 optionally, a scale removal enhancer; 
 a carboxyl-containing fructan such as carboxymethyl inulin; and 
   exposing said surface contaminated with said barium sulfate scale to the liquid composition;   allowing sufficient time of exposure to remove particles of barium sulfate scale from the contaminated surface;   wherein said particles of barium sulfate complexted with the carboxymethyl inulin and have a particle size of less than 1 micron; and   allowing the pH of the solution to drop from a pH ranging from 10 to 11 to a pH ranging from 7 to 8 thereby causing a reprecipitation of the solubilzed barium sulfate to a particle size of less than 1 micron.   
     
     
         17 . The method according to  claim 16 , wherein the carboxyl-containing fructan is carboxymethylinulin (CMI). 
     
     
         18 . The method according to  claim 16  wherein the composition comprises:
 a chelating agent selected from the group consisting of: Li 5 DTPA; Na 5 DTPA; K 5 DTPA; Cs 5 DTPA; Na 4 EDTA; K 4 EDTA; TEAH 4 DTPA; and TBAH 5 DTPA; 
 optionally, a scale removal enhancer; 
 carboxymethyl inulin; and 
 sodium gluconate 
 
     
     
         19 . The method according to  claim 16  wherein the scale removal enhancer is selected from the group consisting of: potassium carbonate; potassium formate; cesium formate and cesium carbonate and combinations thereof.