Scale control composition for high scaling environments

Abstract

A barium sulfate and/or calcium carbonate scale inhibitor composition is presented composed of a water-soluble polymer having incorporated phosphate functionality, the polymer being formed from at least one ethylenically unsaturated carboxylic acid monomer, at least one ethylenically unsaturated vinyl sulphonate monomer, or a mixture thereof. The scale inhibitor composition can also be used as a means of detecting the inhibitor composition in downhole and topside oilfield treatments by means that are faster and more accurate than turbidometric measurement.

What is claimed is:  
     
         1 . A scale inhibitor composition for barium sulfate and calcium carbonate scale comprising a water-soluble polymer having incorporated phosphate functionality, wherein said polymer is formed from monomers selected from the group consisting of 
 a) at least one ethylenically unsaturated (di)carboxylic acid monomer,    b) at least one ethylenically unsaturated vinyl sulphonate monomer, and    c) a mixture thereof.    
     
     
         2 . The scale inhibitor of  claim 1  wherein said carboxylic acid monomer comprises (meth)acrylic acid, maleic acid, maleic anhydride, or a mixture thereof.  
     
     
         3 . The scale inhibitor of  claim 1  wherein said vinyl sulphonate monomer comprises vinyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, or a mixture thereof.  
     
     
         4 . The scale inhibitor of  claim 1  comprising 0.5 to 50 mole percent of said sulfonate monomer.  
     
     
         5 . The scale inhibitor of  claim 1  comprising 0.5 to 50 mole percent of said carboxylic acid monomer.  
     
     
         6 . The scale inhibitor of  claim 1  wherein said phosphate functionality comprises from 0.5 to 50 mole percent of a phosphate functional monomer incorporated into said water-soluble polymer, based on the total moles of monomer.  
     
     
         7 . The scale inhibitor of  claim 1  wherein said polymer is formed from monomers comprising both at least one carboxylic acid monomer, and at least one sulphonate monomer.  
     
     
         8 . The scale inhibitor of  claim 6 , wherein said phosphate functional monomer comprises at least one of ethylene glycol methacrylate phosphate and/or oleyl ethoxylate phosphate ester.  
     
     
         9 . The scale inhibitor of  claim 1  wherein said polymer further is formed from at least one other ethylenically unsaturated monomer.  
     
     
         10 . The scale inhibitor of  claim 1  wherein the polymer has a molecular weight of from 500 to 50,000.  
     
     
         11 . The scale inhibitor composition of  claim 1  further comprising barium ions, strontium ions, calcium ions, or a mixture thereof.  
     
     
         12 . An oil containing formation having absorbed thereon the inhibitor composition of  claim 1 .  
     
     
         13 . A method for inhibiting the formation of barium sulfate scale comprising: 
 a) forming the inhibitor composition of  claim 1 , and    b) contacting said inhibitor composition with a surface in contact with an aqueous solution containing barium and sulfate ions.    
     
     
         14 . The method of  claim 13  wherein said surface is a subterranean oil-containing formation.  
     
     
         15 . A method for inhibiting calcium carbonate scales in subterranean oil field use comprising: 
 a) forming a sulphonate free inhibitor composition of  claim 1;     b) contacting said inhibitor composition with a subterranean oil-containing formation.    
     
     
         16 . A method for detecting the concentration of an inhibitor solution for use in subterranean oil field use comprising: 
 a) forming the inhibitor composition of  claim 1;     b) injecting said inhibitor composition into a subterranean oil-containing formation;    c) bringing a aqueous solution containing the inhibitor composition from the subterranean oil-containing formation to a location above the oil-containing formation, and    d) analyzing for the phosphate moiety.    
     
     
         17 . The method of  claim 16  wherein the analysis for the phosphate moiety is used to calculate the concentration of the inhibitor composition.  
     
     
         18 . The method of  claim 16  wherein said analyzing for the phosphate moiety comprises using either inductively coupled plasma—atomic emission spectroscopy (ICP-AES) or a colourimetric complexation of free phosphate from UV degraded polymer solution  
     
     
         19 . The method of  claim 16  wherein said inhibitor composition is sulphonate-free.  
     
     
         20 . The method of  claim 16  wherein the analysis for the phosphate moiety is not by a turbidometric method.