This is the second article in a series reviewing 2014 patents focused on Enhanced Oil Recovery (EOR). The initial article (see HERE) reviewed the area of Microbial Enhanced Oil Recovery, which concerns the use of microbes to extract oil from oil-containing formations. This and the next few articles relate to patents directed to chemical additives used in the EOR process. This is the case since there are a large number of patents related to EOR additives, so they will be divided into several sections and reviewed separately. In particular, this article will deal with patents directed to demulsifiers.

Chemical methods of EOR recovery generally include polymer flooding, chemical flooding, liquid carbon dioxide flooding, and hydrocarbon displacement. Additives used in this area employ a variety of mechanisms, e.g., a reduction in the oil-water interfacial tension, alteration of surface wettability, and the use of high viscosity agents for mobility control. The objective is generally to increase the mobility of the oil phase relative to the water used in flooding the well to maximize oil recovery. To improve operability and performance, EOR applications sometimes use a combination of surfactant and polymer, known as “SP” formulations and alkaline, surfactant and polymer systems, known as “ASP” formulations.

The SP or ASP systems are often complex systems, particularly designed for the crude of interest and the geology of the wellbore, and are very effective, however, in enhanced oil recovery processes, emulsions can form (oil in water or water in oil). Ultimately the emulsified oil/water stream must necessarily be “demulsified” back to oil and water streams, to maximize oil recovery, and minimize oil contamination of the water that is returned to the environment.

Review of recent patents in the demulsifier area reflect a corresponding complexity. One of the patents, (U.S. 8,697,615), is directed to systems containing polyepihalohydrins. U.S. 8,779,012 is directed to a demulsifying composition containing at least one polyorganosiloxane compound. U.S. 8,741,130 is directed to a process for resolving emulsions using a composition comprising a cationic surfactant containing one or more bolaform surfactant and one or more gemini surfactants. U.S. 8,911,615 generally relates to a method for demulsifying oil and water with a composition containing a combination of a cationic alkyl ammonium halide surfactant and an amphoteric betaine surfactant comprising cocoamino-propionic acid.

Enhanced Oil Recovery demulsifier patents are summarized below. Attached Table 1 lists relevant information on the demulsifier patents reviewed. Table 2 contains a representative independent claim from each.

Demulsifiers

U.S. Patent No. 8,697,615 generally relates to compositions for breaking reverse emulsions, i.e., reverse oil emulsions or oil-in-water emulsions. The compositions include a particular class of polyepihalohydrins (see claim 1 for the structure), with preferred polyepihalohydrins being polyepichlorohydrin, polyepibromohydrin and polyepiiodohydrin.   The polyepihalohydrins can be used in emulsions from an alkali-surfactant-polymer or surfactant-polymer enhanced oil recovery flood.

U.S. Patent No. 8,741,130 generally relates to a process for resolving emulsions produced in an enhanced oil recovery process. The process uses a cationic surfactant containing one or more bolaform surfactant and one or more gemini surfactants. Bolaform surfactants have two hydrophilic groups and one hydrophobic group, with the two hydrophilic groups generally being at both ends of a non-polar chain. Gemini surfactants have two hydrophilic and two hydrophobic groups, and generally are amphiphilic, having two hydrocarbon tails and two ionic groups linked by a spacer which may be C2-C12.

U.S. Patent No. 8,779,012 generally relates to a demulsifying composition containing an oil phase an aqueous phase and at least one polyorganosiloxane compound (see claim 1 for the structure).

U.S. Patent No. 8,911,615 generally relates to a method for demulsifying oil and water with a composition containing a combination of a cationic alkyl ammonium halide surfactant and an amphoteric betaine surfactant comprising cocoamino-propionic acid. The composition contains 100 ppm to 20,000 ppm of cationic alkyl ammonium halide surfactant, where the halide of the cationic alkyl ammonium halide surfactant doesn’t comprise chlorine.

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Patent Number U.S. 8,697,615

Claim 1. A method for resolving an emulsion of water and oil, the method comprising adding an effective amount of a reverse emulsion breaker composition to the emulsion of water and oil, the composition comprising at least one polyepihalohydrin having the following structure;

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wherein, X is selected from chloride, bromide, iodide, trifluoromethylsulfonate, toluenesulfonate, methylsulfonate, and combinations thereof; wherein y1 is from about 2 to about 20; wherein y2 is from about 2 to about 20; and wherein y3 is from about 2 to about 20.

 Patent Number U.S. 8,741,130

Claim 1. A method of demulsifying an emulsion comprising water and oil, the method comprising adding an effective amount of a composition comprising a cationic surfactant to the emulsion to form a mixture and optionally applying heat to the mixture, wherein the cationic surfactant comprises one or more bolaform surfactants, one or more gemini surfactants, or any combination of the foregoing; wherein the bolaform surfactant is selected from the group consisting of: alkyl-bis(trimethylammonium halide); alkyl-bis(benzyldimethyl ammonium halide); alkyl-bis(amidopropyl-N-benzyl-N,N-dimethylammonium halide); alkyl-bis(amidopropyl-N,N,N-trimethylammonium halide); and any combination thereof, wherein the bolaform surfactant has an average alkyl chain length of C6to C24; and wherein the gemini surfactant is selected from the group consisting of: (C2-C12)-bis(dimethylalkylammonium halide), (C2-C12)-bis(methylbenzyl alkylammonium halide), and any combination of thereof, wherein the (C2-C12)-bis(dimethylalkylammonium halide) and (C2-C12)-bis(methylbenzyl alkylammonium halide) have an average alkyl chain length of C6 to C16.

Patent Number U.S. 8,779,012

Claim 1. A demulsifying composition comprising an oil phase, and aqueous phase and a demulsifying-effective amount of at least one polyorganosiloxane compound having the general formula (I): M1aM2bD1cD2dT1eT2fQg (I) wherein: M1=R1R2R3SiO1/2, M2=R4R5RLSiO1/2, D1=R6R7SiO2/2, D2=R8RLSiO2/2, T1=R9SiO3/2, T2=RLSiO3/2, Q=SiO4/2, where R1, R2, R3, R4, R5, R6, R7, R8 and R9are each independently chosen from monovalent alkyl, aryl or aralkyl hydrocarbon radicals containing 1 to 60 carbon atoms, optionally containing at least one heteroatom, or at least one monovalent polyether radical having the general formula RP; RP is a monovalent polyether radical independently of the general formula (II): –(CnH2n)–O–(C2H4O)o–(C3H6O)P– -(C4H8O)q–R10 (II) where R10 is hydrogen or a monovalent alkyl radical containing from 1 to about 20 carbon atoms or an acyl group; subscripts a, b, c, d, e, f and g are zero or positive integers, subject to the limitations: 2<a+b+c+d+e+f+g<500, b+d+f>1 and a+b=2+e+f+2g; subscript n is 2 to about 10; subscript o is 0 to about 200; subscript p is 0 to about 200; subscript q is 0 to about 200; and, subject to the limitation o+p+q>1; RL is a monovalent radical independently chosen from the general formula (III): –X–O–(C2H4O)r–(C3H6O)s–(C4H8- O)t–{C(O)CuH2uO}v–R11(III) where R11 is hydrogen or monovalent alkyl radical containing from 1 to about 20 carbon atoms or an acyl group, and where X is a linear, branched or cyclic divalent hydrocarbon or aralkyl radical containing from 2 to about 20 carbon atoms, optionally containing at least one heteroatom; subscript r is 0 to about 200; subscript s is 0 to about 200; subscript t is 0 to about 200; subscript u is 1 to about 20; subscript v is 1 to about 200, and subject to the limitation if r+s+t is equal to zero then the polyorganosiloxane contains at least one RP radical.

Patent Number U.S. 8,911,615

Claim 1. A method of demulsifying an emulsion comprising oil and water, the method comprising: adding a composition to an oil-in-water emulsion, wherein the composition comprises a combination of a cationic alkyl ammonium halide surfactant and an amphoteric betaine surfactant comprising cocoaminopropionic acid, wherein the composition further comprises from about 100 ppm to about 20,000 ppm cationic alkyl ammonium halide surfactant, and wherein the halide of the cationic alkyl ammonium halide surfactant does not comprise chlorine.