Solid-liquid separation of oil-based muds

Abstract

This invention relates to a method of achieving a solid-liquid separation of an oil-based mud comprising the step of contacting said oil-based mud with a water-in-oil emulsion comprising a polymer derived from at least one water-soluble monomer, where the polymer is not dissolved prior to contact with the oil-based mud, mixing the water-in-oil emulsion and the oil-based mud and separating the solid phase from the liquid phase in the oil-based mud. In addition, this invention also relates to a composition comprising an oil-based mud with a water-in-oil emulsion comprising a polymer derived from at least one water-soluble monomer, wherein the polymer is not dissolved prior to contact with the oil-based mud.

1 . A composition comprising the product obtained on contacting an oil-based mud with a water-in-oil emulsion; 
 wherein the water-in-oil emulsion comprises a polymer derived from at least one water-soluble monomer;    wherein the polymer is not dissolved prior to the contact of the oil-based mud with the water-in-oil emulsion;    wherein the composition comprises a continuous oil phase and a discontinuous aqueous phase; and    wherein the discontinuous aqueous phase comprises the polymer in the form of polymer particles having an average discrete phase particle size less than about 10 microns.    
     
     
         2 . The composition of  claim 1 , wherein the composition is solid-liquid separated.  
     
     
         3 . The composition of  claim 1 , wherein the at least one water soluble monomer is selected from the group consisting of (alkyl)acrylamide, (alkyl)acrylic acid, N-vinylpyrrolidone, N-vinylacetamide, N-vinylformamide, acrylonitrile, fumaric acid, crotonic acid, maleic acid, hydroxyalkyl methacrylates, 2-acrylamido-2-alkylsulfonic acids wherein the alkyl group contains 1 to 6 carbon atoms, styrene sulfonic acids; salts of any of the foregoing, and monomers having the structure of Formulas I, II or III  
       
         
           
           
               
               
           
         
         wherein R 1 , R 2 , and R 5  are each independently hydrogen or a C 1  to C 6  alkyl; R 3  and R 4  are each independently hydrogen, a C 1  to C 12 alkyl, aryl, arylalkyl or hydroxyethyl; and R 2  and R 4  or R 2  and R 3  can combine to form a cyclic ring containing one or more hetero atoms; Z is the conjugated base of an acid, X is oxygen or —NR 6  wherein R 6  is hydrogen or a C 1  to C 6  alkyl; and A is a C 1  to C 12 alkylene.  
       
     
     
         4 . The composition of  claim 1 , wherein the at least one water-soluble vinyl monomer is selected from the group consisting of (alkyl)acrylamide, (alkyl)acrylic acid and its salts, N,N-dimethylaminoethyl(meth)acrylate and its salts, and vinyl sulfonic acid.  
     
     
         5 . The composition of  claim 3 , wherein the polymer is a copolymer of monomers consisting of an (alkyl)acrylamide monomer and at least one second monomer selected from the group consisting of N-vinylpyrrolidone, N-vinylacetamide, N-vinylformamide, acrylonitrile, acrylic acid, methacrylic acid, ethylacrylic acid, fumaric acid, crotonic acid, maleic acid, hydroxyalkyl methacrylates, 2-acrylamido-2-alkylsulfonic acids wherein the alkyl group contains 1 to 6 carbon atoms, styrene sulfonic acids, vinyl sulfonic acid, and salts of any of the foregoing, and monomers of Formulas I, II or III.  
     
     
         6 . The composition of  claim 1 , wherein the polymer is a copolymer of monomers consisting of (meth)acrylamide and at least one second monomer selected from the group consisting of N,N-dimethylaminoethyl(meth)acrylate and its salts, quaternary N,N-dimethylaminoethyl(meth)acrylates, tertiary and quaternary N,N-dimethylaminopropyl acrylamides, tertiary and quaternary N,N-dimethylaminomethyl acrylamides, and diallyl dimethyl ammonium halides.  
     
     
         7 . The composition of  claim 1 , wherein the polymer is anionic and is derived from copolymerization of monomers consisting of (meth)acrylamide and (meth)acrylic acid.  
     
     
         8 . The composition of  claim 1 , wherein the polymer is branched or crosslinked.  
     
     
         9 . The composition of  claim 1 , wherein the concentration of the polymer in the water-in-oil emulsion is about 10% to about 70% by weight based on the total weight of the emulsion.  
     
     
         10 . The composition of  claim 1 , wherein the water-in-oil emulsion is pre-dispersed with a pre-dispersion oil before contacting with the oil-based mud.  
     
     
         11 . The composition of  claim 10 , wherein the pre-dispersion oil is kerosene, diesel, paraffin blends, internal olefins, or C 16 -C 18  alkene blends.  
     
     
         12 . The composition of  claim 10 , wherein the concentration of the polymer in the water-in-oil emulsion is about 0.1% to about 10% by weight based on the total weight of the emulsion.  
     
     
         13 . The composition of  claim 1 , wherein the composition further comprises a surfactant that is a sulfosuccinate and/or a sulfosuccinamate.  
     
     
         14 . The composition of  claim 1 , wherein the composition further comprises a surfactant that is a dioctylsulfosuccinate, a dicarboxyethyl octadecylsulfosuccinamate, or a mixture thereof.  
     
     
         15 . The composition of  claim 1 , wherein the polymer is derived solely from the at least one water-soluble monomer.  
     
     
         16 . A composition comprising the product obtained on contacting an oil-based drilling mud with a water-in-oil emulsion; 
 wherein the water-in-oil emulsion comprises a polymer derived from monomers consisting of acrylamide and at least one second monomer selected from the group consisting of 2-acryloyloxyethyltrimethylammonium chloride, 2-methacryloyloxyethyltrimethylammonium chloride, N,N-dimethylaminoethyl methacrylate and its acid salts, N,N-dimethylaminoethyl acrylate and its acid salts, methacrylamidopropyltrimethylammonium chloride, ammonium acrylate, and sodium acrylate;    wherein the polymer is not dissolved prior to the contact of the oil-based mud with the water-in-oil emulsion;    wherein the composition comprises a continuous oil phase and a discontinuous aqueous phase; and    wherein the discontinuous aqueous phase comprises the polymer in the form of polymer particles having an average discrete phase particle size less than about 10 microns.    
     
     
         17 . A composition comprising the product obtained on contacting an oil-based drilling mud with a water-in-oil emulsion; 
 wherein the water-in-oil emulsion comprises a polymer derived from monomers consisting of acrylamide and at least one second monomer selected from the group consisting of 2-acryloyloxyethyltrimethylammonium chloride, 2-methacryloyloxyethyltrimethylammonium chloride, N,N-dimethylaminoethyl methacrylate and its acid salts, N,N-dimethylaminoethyl acrylate and its acid salts, and methacrylamidopropyltrimethylammonium chloride;    wherein the polymer is not dissolved prior to the contact of the oil-based mud with the water-in-oil emulsion;    wherein the composition comprises a continuous oil phase and a discontinuous aqueous phase; and    wherein the discontinuous aqueous phase comprises the polymer in the form of polymer particles having an average discrete phase particle size less than about 10 microns.