# US 11,078,394 B2 · Cationic coatings for improved nanoparticle transport in a carbonate reservoir > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,078,394 B2 - Document ID: US11078394B2 - Status: Granted - Kind: B2 - Application number: 16/291,601 - Filed: 2019-03-04 - Published: 2020-09-10 - Granted: 2021-08-03 - Earliest claimed: 2019-03-04 - Assignees: Saudi Arabian Oil Company - Applicants: Saudi Arabian Oil Company - Inventors: Erika Shoemaker Ellis; Howard K. Schmidt - Web page: https://patentgrep.com/patent/US11078394B2 ## CPC - C09K 8/08: containing natural organic compounds, e.g. polysaccharides, or derivatives thereof - C09K 8/58: Compositions for enhanced recovery methods for obtaining hydrocarbons, i.e. for improving the mobility of the oil, e.g. displacing fluids - C09K 8/05: containing inorganic compounds only, e.g. mixtures of clay and salt - C09K 8/12: containing synthetic organic macromolecular compounds or their precursors - C09K 8/584: characterised by the use of specific surfactants - C09K 2208/10: Nanoparticle-containing well treatment fluids - C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE ## Abstract Coated nanoparticles include nanoparticles with a cationic coating, such that the nanoparticles have a net-positive charge. The cationic coatings may be selected from an amino acid, a polysaccharide, a polyamine, an acrylate polymer, a dendrimer, a copolymer, a histone, a protein, an ester, or combinations thereof. The coated nanoparticles may be incorporated into methods for improving an amount of oil recovered during enhanced oil recovery. The methods may include introducing an aqueous drilling fluid comprising coated nanoparticles to a carbonate reservoir and injecting drilling fluid comprising the coated nanoparticles into the carbonate reservoir to displace oil in the carbonate reservoir and thereby enhance the oil recovery. ## Claims ### Claim 1 A method for enhancing oil recovery comprising: introducing a drilling fluid comprising an aqueous base fluid and a group of coated nanoparticles to a carbonate reservoir, the carbonate reservoir having a net-positive charge, in which: the group of coated nanoparticles consist of nanoparticles and a cationic coating, each of the nanoparticles is coated with the cationic coating, the cationic coating has a net-positive charge, and in which each coated nanoparticle has a net-positive charge; and injecting the drilling fluid comprising the coated nanoparticles into the carbonate reservoir to displace oil in the carbonate reservoir and thereby enhance the oil recovery, the coated nanoparticles being retained within the drilling fluid with reduced agglomeration in the carbonate reservoir due to electrostatic repulsion, the electrostatic repulsion being produced by the interaction of the positive charge of the coated nanoparticles and the positive charge of the carbonate reservoir. ### Claim 2 (depends on 1) The method of claim 1, in which the cationic coating is selected from an amino acid, a polysaccharide, a polyamine, an acrylate polymer, a dendrimer, a copolymer, a histone, a protein, an ester, or combinations thereof. ### Claim 3 (depends on 1) The method of claim 1, in which the cationic coating comprises an amino acid. ### Claim 4 (depends on 3) The method of claim 3, in which the amino acid is selected from poly-1-lysine, poly-1-arginine, poly-1-histidine, or combinations thereof. ### Claim 5 (depends on 1) The method of claim 1, in which the cationic coating comprises polysaccharide. ### Claim 6 (depends on 5) The method of claim 5, in which the polysaccharide is selected from chitosan, cyclodextrin, α-cyclodextrin, or combinations thereof. ### Claim 7 (depends on 1) The method of claim 1, in which the cationic coating comprises polyamine. ### Claim 8 (depends on 7) The method of claim 7, in which the polyamine comprises polyethyleneimine. ### Claim 9 (depends on 1) The method of claim 1, in which the cationic coating comprises an acrylate polymer. ### Claim 10 (depends on 9) The method of claim 9, in which the acrylate polymer is selected from poly(methyl acrylate), poly(ethyl acrylate), polymethacrylate, polyacrylamine, poly(dimethylaminoathyl methacrylate), or combinations thereof. ### Claim 11 (depends on 1) The method of claim 1, in which the cationic coating comprises a dendrimer. ### Claim 12 (depends on 11) The method of claim 11, in which the dendrimer is selected from poly(amidoamine), poly(propylene imine), poly(etherhydroxylamine), or combinations thereof. ### Claim 13 (depends on 1) The method of claim 1, in which the cationic coating comprises a copolymer. ### Claim 14 (depends on 13) The method of claim 13, in which the copolymer comprises poly(lactic-co-glycolic acid). ### Claim 15 (depends on 1) The method of claim 1, in which the cationic coating comprises a histone. ### Claim 16 (depends on 15) The method of claim 15, in which the histone is selected from H2A, H2B, H3, H4, H1, or combinations thereof. ### Claim 17 (depends on 1) The method of claim 1, in which the cationic coating comprises a protein. ### Claim 18 (depends on 17) The method of claim 17, in which the protein comprises a collagen. ### Claim 19 (depends on 1) The method of claim 1, in which the cationic coating comprises an ester. ### Claim 20 (depends on 19) The method of claim 19, in which the ester comprises poly(b-amino ester). ### Claim 21 (depends on 1) The method of claim 1, in which the nanoparticles comprise metal oxide, silica, polymers, or combinations thereof. ### Claim 22 (depends on 21) The method of claim 21, in which the metal oxide is selected from aluminum oxide, iron oxide, nickel oxide, titanium oxide, zinc oxide, zirconium oxide, or combinations thereof. ### Claim 23 (depends on 1) The method of claim 1, in which the nanoparticles have a diameter ranging from 1 nm to 100 nm. ### Claim 24 (depends on 1) The method of claim 1, in which the aqueous solution comprises fresh water, saline, or combinations thereof. ### Claim 25 A method for enhancing oil recovery comprising: introducing a drilling fluid comprising an aqueous base fluid and a group of coated nanoparticles to a carbonate reservoir, the carbonate reservoir having a net-positive charge, in which the group of coated nanoparticles consist of nanoparticles and a cationic coating, in which: each of the nanoparticles is coated with the cationic coating, the cationic coating has a net-positive charge, and the drilling fluid does not include coated nanoparticles having a net-negative charge; and injecting the drilling fluid comprising the coated nanoparticles into the carbonate reservoir to displace oil in the carbonate reservoir and thereby enhance the oil recovery, the coated nanoparticles being retained within the drilling fluid with reduced agglomeration in the carbonate reservoir due to electrostatic repulsion, the electrostatic repulsion being produced by the interaction of the positive charge of the coated nanoparticles and the positive charge of the carbonate reservoir. ### Claim 26 A method for enhancing oil recovery comprising: introducing a drilling fluid consisting essentially of an aqueous base fluid and a group of coated nanoparticles to a carbonate reservoir, the carbonate reservoir having a net-positive charge, in which: the group of coated nanoparticles consist of nanoparticles and a cationic coating, each of the nanoparticles is coated with the cationic coating, and the cationic coating has a net-positive charge; and injecting the drilling fluid into the carbonate reservoir to displace oil in the carbonate reservoir and thereby enhance the oil recovery, the coated nanoparticles being retained within the drilling fluid with reduced agglomeration in the carbonate reservoir due to electrostatic repulsion, the electrostatic repulsion being produced by the interaction of the positive charge of the coated nanoparticles and the positive charge of the carbonate reservoir.