Defoaming Compositions and Processes for Cementing Applications

Abstract

Cement compositions and processes for reducing air entrainment in a cement composition generally include mixing a hydraulic cement with a defoamer composition including an organic acid ester of a polyoxyethylene-polyoxypropylene block copolymer.

What is claimed is: 
     
         1 . A process for reducing air entrainment in a cement composition, the process comprising:
 adding a defoaming composition to a cement composition, wherein the defoaming composition comprises an organic acid ester of a polyoxyethylene-polyoxypropylene block copolymer; and   reducing air entrainment in the cement composition relative to a cement composition without the defoaming composition.   
     
     
         2 . The process of  claim 1 , wherein the organic acid ester of the polyoxyethylene-polyoxypropylene block copolymer is a condensation reaction product of a polyoxyethylene-polyoxypropylene block copolymer and an organic acid having at least one carboxylic acid group. 
     
     
         3 . The process of  claim 1 , wherein the organic acid ester of the polyoxyethylene-polyoxypropylene block copolymer is of the general structure: 
       
         
           
           
               
               
           
         
       
       wherein R is a linear or branched, saturated or unsaturated alkyl group or alkyl carboxylate group or aryl or aryl carboxylate group having from 3 to 40 carbon atoms, a is 2 to 8 moles and b is 16 to 67 moles. 
     
     
         4 . The process of  claim 2 , wherein the organic acid is selected from the group consisting of mono-carboxylic acids, dicarboxylic acids, and multicarboxylic acids. 
     
     
         5 . The process of  claim 1 , wherein the organic acid ester of the polyoxyethylene-polyoxypropylene block copolymer has an average molecular weight of 1000 to 5000 Daltons. 
     
     
         6 . The process of  claim 1 , wherein the acid ester of the polyoxyethylenepolyoxypropylene block copolymer has an acid number less than 15. 
     
     
         7 . The process of  claim 1 , wherein adding the defoaming composition to the cement composition is at 0.01 to 1% by weight of the cement. 
     
     
         8 . The process of  claim 1 , further comprising hydrophobic solids. 
     
     
         9 . The process of  claim 8 , wherein a weight ratio of the hydrophobic silica to the acid ester of the polyoxyethylene-polyoxypropylene block copolymer is between 0.1 to 10 weight percent. 
     
     
         10 . The process of  claim 8 , wherein the hydrophobic silica is hydrophobized silica fume or precipitated silica or a mixture thereof. 
     
     
         11 . The process of  claim 1 , wherein the polyoxyethylene-polyoxypropylene block copolymer is random. 
     
     
         12 . The process of  claim 1 , wherein the polyoxyethylene-polyoxypropylene block copolymer is ordered having a polyoxypropylene backbone and polyoxyethylene end groups or a polyoxyethylene backbone and polyoxypropylene end groups.