Demulsifiers for crude oil based on acrylic-aminoacrylic random copolymers of controlled molecular mass

Abstract

Nowadays, one of the major problems of the oil industry is the presence of large amounts of water and salts, which cannot be efficiently removed by conventional dehydrating polymers. In addition, the acid stimulation operations of petroleum wells cause the chemical degradation of demulsifiers such as polyethers and phenolic resins, reducing drastically their efficiency as water and salt removers. Based on aforementioned, a series of new copolymers has been developed, where the copolymers are combinations of an acrylic and an aminoacrylic monomer and are synthesized by semi-continuous emulsion polymerization (under starved feed conditions), which ensures both the homogeneity of the different chains as well as the randomness of the monomers distribution. The solutions of one of these random copolymers have shown an efficiency similar or superior to combinations of two or three block copolymers (formulations), when they are applied in light or heavy crude oils. The acrylic-aminoacrylic copolymers show good performance as water/oil emulsion breaker initiators, coalescence agents of water droplets and clarifiers of the remaining aqueous phase. In addition, the chemical structure of the acrylic copolymers confers resistance to degradation induced by abrupt pH changes when acid stimulation operations of wells are performed.

1 . Random copolymers based on alkyl acrylate and aminoalkyl acrylate monomers, as dehydrating agents to remove water emulsified in crude oil with densities from 10 to 40° API, having the structural formula (2), with molecular weights between 1000 and 180,000 g/mol. 
       
         
           
           
               
               
           
         
         wherein: 
         R 1 , R 2 , R 3  and R 4  are independent radicals represented by the groups mentioned bellow: 
         R 1  and R 3 ═H (hydrogen), CH 3  (methyl); 
         R 2 ═CH 3  (methyl), C 2 H 5  (ethyl), C 4 H 9  (n-butyl, isobutyl), C 6 H 13  (n-hexyl, iso-hexyl), C 8 H 17  (2 ethyl-hexyl), C 8 H 17  (n-octyl), C 10 H 21  (n-decyl, iso-decyl), C 12 H 25  (n-dodecyl), C 18 H 37  (n-octadecyl), C 8 H 9 O (2-phenoxyethyl), C 3 H 7 O (2-methoxyethyl), and C 5 H 11 O 2  (2-(2-methoxyethoxy)ethyl), wherein the aliphatic chain may contain heteroatoms of the ether group, or aromatic rings or rings with heteroatoms of the ether type; 
         R 4 ═CH 2 NH 2  (methylamine), CH 2 CH 2 NH 2  (2-ethylamine), CH 2 CH 2 CH 2 NH 2  (3-propylamine), CH 2 CH(NH 2 ) 2  (2-dimethylamino), (CH 2 CH 2 N(CH 3 ) 2 ) 2-(dimethylamino)ethyl, (CH 2 CH 2 N(CH 2 CH 3 ) 2 ), 2-(dimethylamino)ethyl, (CH 2 CH 2 CH 2 N(CH 3 ) 2 ), 3-(dimethylamino)propyl, (C 6 H 12 NO) N-ethylmorpholine. 
         wherein, 
         x=is a number from 2 to 900; 
         y=is a number from 2 to 900; and 
         “x” and “y” are in random sequences. 
       
     
     
         2 . The random copolymers of  claim 1 , wherein R 2  is selected from the group consisting of methyl, ethyl, n-butyl, isobutyl, n-hexyl, iso-hexyl, 2 ethyl-hexyl, n-octyl, n-decyl, iso-decyl, n-dodecyl, n-octadecyl, 2-phenoxyethyl, and 2-(2-methoxyethoxy)ethyl. 
     
     
         3 . The random copolymers of  claim 1 , wherein R 2  is selected from the group consisting of methyl, ethyl, n-butyl, isobutyl, n-hexyl, iso-hexyl, 2 ethyl-hexyl, n-octyl, n-decyl, iso-decyl, n-dodecyl, n-octadecyl, 2-phenoxyethyl, and 2-(2-methoxyethoxy)ethyl. 
     
     
         4 . The random copolymers of  claim 1 , wherein R 1  is hydrogen, R 2  is n-butyl, R 3  is hydrogen, and R 4  is 2-ethylamino. 
     
     
         5 . The random copolymers of  claim 1 , wherein R is hydrogen, R 2  is hydrogen, R 3  is hydrogen, and R 4  is 2-(dimethylamino) ethyl. 
     
     
         6 . The random copolymers of  claim 1 , wherein R 1  is hydrogen, R 2  is n-hexyl, R 3  is hydrogen, and R 4  is 3-aminopropyl. 
     
     
         7 . The random copolymers of  claim 1 , wherein R 4  is selected from the group consisting of methylamine, 2-ethylamine, 3-propylamine, 2-dimethylamino, and N-ethylmorpholine. 
     
     
         8 . The random copolymers of  claim 1 , wherein R 4  is selected from the group consisting of methylamine, 2-ethylamine, 3-propylamine, 2-dimethylamino, and (C 6 H 12 NO) N-ethylmorpholine. 
     
     
         9 . A random copolymer based on alkyl acrylate and aminoalkyl acrylate monomers, said random copolymer having the structural formula (2) and a molecular weight between 1000 and 180,000 g/mol 
       
         
           
           
               
               
           
         
         wherein: 
         R 1 , R 2 , R 3  and R 4  are independent radicals represented by the groups mentioned bellow: 
         R 1  and R 3 ═H (hydrogen), CH 3  (methyl); 
         R 2  is selected from the group consisting of methyl, ethyl, n-butyl, isobutyl, n-hexyl, iso-hexyl, 2 ethyl-hexyl, n-octyl, n-decyl, iso-decyl, n-dodecyl, n-octadecyl, 2-phenoxyethyl, and 2-(2-methoxyethoxy)ethyl, wherein the aliphatic chain may contain an aromatic ring; 
         R 4  is selected from the group consisting of methylamine, 2-ethylamine, 3-propylamine, 2-dimethylamino, 2-(dimethylamino)ethyl, 2-(diethylamino)ethyl, 3-(dimethylamino)propyl, and N-ethylmorpholine; 
         wherein, 
         x is a number from 2 to 900; 
         y is a number from 2 to 900; and “x” and “y” are in random sequences. 
       
     
     
         10 . A method for the synthesis of random copolymers based on alkyl acrylate and aminoalkyl acrylate monomers according to  claim 1 , as dehydrating agents of crude oils, wherein said synthesis is carried out by semi-continuous emulsion polymerization. 
     
     
         11 . A method for the synthesis of a random copolymer, based on alkyl acrylate and aminoalkyl acrylate monomers according to  claim 1 , wherein the method reacts at least one alkyl acrylate monomer and at least one aminoalkyl acrylate monomer, where the acrylate monomer is selected from the group consisting of methyl acrylate, ethyl acrylate, butyl acrylate, n-amyl acrylate, isobornyl acrylate isobutyl acrylate, tert-butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, 3,5,5-trimethylhexyl acrylate, 2-methoxiethyl acrylate, 2-phenoxiethyl acrylate, 4-tert-butylcyclohexyl acrylate, octyl acrylate, isodecyl acrylate, decyl acrylate, lauryl acrylate, tridecyl acrylate, octadecyl acrylate, and behenyl acrylate. 
     
     
         12 . A method for the synthesis of a random copolymer based on alkyl acrylate and aminoalkyl acrylate monomers according to  claim 1 , wherein the method reacts at least one alkyl acrylate monomer and at least one aminoalkyl acrylate monomer, wherein the aminoacrylic monomer is selected from the group consisting of 2-ethylamino acrylate, 2-ethylamino methacrylate, 2-(dimethylamino)ethyl acrylate, 2-(dimethylamino)ethyl methacrylate, 3-propylamino acrylate, 3-(dimethylamino)propyl acrylate, 2-(diethylamino)ethyl acrylate, 2-(diethylamino)ethyl methacrylate, and 2-N-ethylmopholine methacrylate. 
     
     
         13 . The method of synthesis of  claim 11 , wherein said the aminoacrylic monomer is selected from the group consisting of 2-ethylamino acrylate, 2-ethylamino methacrylate, 2-(dimethylamino)ethyl acrylate, 2-(dimethylamino)ethyl methacrylate, 3-propylamino acrylate, 3-(dimethylamino)propyl acrylate, 2-(diethylamino)ethyl acrylate, 2-(diethylamino)ethyl methacrylate, and 2-N-ethylmopholine methacrylate. 
     
     
         14 . A method of producing a dehydrating agent for crude oil comprising adding an organic solvent to the random copolymer of  claim 1 , wherein said organic solvent is selected from the group consisting of dichloromethane, methanol, ethanol, isopropanol, chloroform, benzene and its derivatives, toluene, xylene, turbosine and naphtha, and mixtures thereof. 
     
     
         15 . The method of producing the dehydrating agent according to  claim 14 , comprising adding said organic solvent with said random copolymer in an amount to provide said dehydrating agent with said random copolymer in an amount of 10 wt % to 50 wt %.