# US 2019/0169487 A1 · Stability improvement of foams for enhanced oil recovery applications using polyelectrolytes and polyelectrolyte complex nanoparticles

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- Number: US 2019/0169487 A1
- Document ID: US20190169487A1
- Status: Published application
- Kind: A1
- Application number: 16/270,144
- Filed: 2019-02-07
- Published: 2019-06-06
- Earliest claimed: 2015-08-11
- Assignees: University of Kansas
- Applicants: The University of Kansas
- Inventors: REZA BARATI GHAHFAROKHI
- Web page: https://patentgrep.com/patent/US20190169487A1

## CPC

- C09K 8/594: Compositions used in combination with injected gas {, e.g. CO2 orcarbonated gas}(C09K8/592 takes precedence)
- C09K 8/584: characterised by the use of specific surfactants
- C09K 8/588: characterised by the use of specific polymers {(polymeric surfactants C09K8/584)}
- E21B 43/164: {Injecting CO2 or carbonated water (in combination with organic material C09K8/594)}
- E21B 43/24: using heat, e.g. steam injection
- C09K 2208/10: Nanoparticle-containing well treatment fluids
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

Polyelectrolyte nanoparticles are generated to stabilize foam for use in enhanced oil recovery. Stability is further enhanced by optimizing pH and a ratio of polycationic and polyanioinic materials, resulting in stronger and longer lasting foams in the presence of crude oil. Use of these nanoparticles results in negligible damage to formation permeability.

## Claims

### Claim 1

A foam comprising:

### Claim 1

a non-liquid fluid phase comprising N2 in a supercritical phase; and
a liquid dispersion phase comprising a dispersion of polyelectrolyte material and surfactant in water, wherein:
the polyelectrolyte material and the surfactant are combined in a ratio of surfactant to polyelectrolyte material ranging from 3:1 to 9:1;
the polyelectrolyte material is present in an amount ranging from about 0.01% to 5% of the liquid phase by weight; and
the polyelectrolyte material forms nanoparticles by electrostatic interaction of a cationic and an anionic polyelectrolyte, the nanoparticles being located at lamellae of the liquid dispersion phase in an effective amount to stabilize the foam.

### Claim 2 (depends on 1)

The foam of claim 1, further comprising a pH adjusting agent in an effective amount to reduce pH of the foam to a value ranging from 5 to 9.

### Claim 3 (depends on 1)

The foam of claim 1, wherein the foam has a foam quality ranging from 60% to 90% of the non-liquid fluid phase by volume.

### Claim 4 (depends on 3)

The foam of claim 3, wherein the foam quality ranges from 80% to 90% of the non-liquid fluid phase by volume.

### Claim 5 (depends on 3)

The foam of claim 3, wherein the foam quality is assessed at conditions of pressure and temperature in a petroleum reservoir.

### Claim 6 (depends on 1)

The foam of claim 1, wherein the surfactant is a nonionic surfactant selected from the group consisting of: cetyl alcohol, stearyl alcohol, cetostearyl alcohol and oleyl alcohol, polyoxyethylene glycol alkyl ethers, octaethylene glycol monododecyl ether, pentaethylene glycol monododecyl ether, polyoxypropylene glycol alkyl ethers, glucoside alkyl ether, decyl glucoside, lauryl glucoside, octyl glucoside, polyoxyethylene glycol octylphenol ethers, polyoxyethylene glycol alkylphenol ethers, glycerol alkyl esters, glyceryl laurate, polyoxyethylene glycol sorbitan alkyl esters, sorbitan alkyl esters, dodecyldimethylamine oxide, block copolymers of polyethylene glycol and polypropylene glycol, and polyethoxylated tallow amine.

### Claim 7 (depends on 1)

The foam of claim 1, wherein the surfactant is an anionic surfactant selected from the group consisting of: ammonium lauryl sulfate, sodium lauryl sulfate, sodium dodecyl sulfate, sodium laureth sulfate, sodium lauryl ether sulfate, sodium myreth sulfate, dioctyl sodium sulfosuccinate, perfluorooctanesulfonate, perfluorobutanesulfonate, an alkyl-aryl ether phosphate, and an alkyl ether phosphate.

### Claim 8 (depends on 1)

The foam of claim 1 wherein the cationic polyelectrolyte is selected from the group consisting of polyethyleneimine, polyallylamine, chitosan, and combinations thereof.

### Claim 9 (depends on 1)

The foam of claim 1 wherein the anionic polyelectrolyte comprises dextran sulfate.

### Claim 10 (depends on 9)

The foam of claim 9 wherein the cationic polyelectrolyte is selected from the group consisting of polyethyleneimine, polyallylamine, chitosan, and combinations thereof.

### Claim 11

A method of foam flooding, comprising the steps of:
introducing a foam into an injection wellbore, the foam comprising:
a non-liquid fluid phase comprising N2 in a supercritical phase; and
a liquid dispersion phase comprising a dispersion of polyelectrolyte material and surfactant in water, wherein:
the polyelectrolyte material and the surfactant are combined in a ratio of surfactant to polyelectrolyte material such that a concentration of the surfactant is below a critical micelle concentration;
the polyelectrolyte material is present in an amount ranging from about 0.01% to 5% of the liquid phase by weight; and
the polyelectrolyte material forms nanoparticles by electrostatic interaction of a cationic and an anionic polyelectrolyte, the nanoparticles being located at lamellae of the liquid dispersion phase in an effective amount to stabilize the foam; and
wherein the foam has a foam quality ranging from 60% to 90% of the total foam volume occupied by the non-liquid fluid phase;
flowing the foam through the injection wellbore for subsequent introduction into rock of an oil reservoir;
flooding the foam from the injection wellbore on a pathway extending from the injection wellbore through the oil reservoir and towards one or more producing wellbores to enhance recovery of oil in place from the oil reservoir.

### Claim 12 (depends on 11)

The method of claim 11, further comprising a step of forming the foam, wherein the foam is formed via inline injection to combine the gas phase with the liquid dispersion phase.

### Claim 13

A foam, comprising:
a non-liquid fluid in a supercritical phase; and
a liquid dispersion phase comprising a dispersion of polyelectrolyte material and surfactant in water, wherein:
the polyelectrolyte material and the surfactant are combined in a ratio of surfactant to polyelectrolyte material such that a concentration of the surfactant is below a critical micelle concentration;
the polyelectrolyte material is present in an amount ranging from about 0.01% to 5% of the liquid phase by weight; and
the polyelectrolyte material forms nanoparticles by electrostatic interaction of a cationic and an anionic polyelectrolyte, the nanoparticles being located at lamellae of the liquid dispersion phase in an effective amount to stabilize the foam;
wherein the foam has a foam quality ranging from 60% to 90% determined as a percentage total foam volume occupied by the gas phase.

### Claim 14 (depends on 13)

The foam of claim 13, wherein the polyelectrolyte material and the surfactant are combined in a ratio of surfactant to polyelectrolyte material ranging from 3:1 to 9:1.

### Claim 15 (depends on 14)

The foam of claim 14, wherein the non-liquid fluid is N2.

### Claim 16 (depends on 14)

The foam of claim 14, wherein the non-liquid fluid is CO2.

### Claim 17 (depends on 13)

The foam of claim 13, wherein the non-liquid fluid is N2.

### Claim 18 (depends on 13)

The foam of claim 13, wherein the surfactant is selected from a group consisting of anionic surfactants, nonionic surfactants and combinations thereof in an amount that is substantially optimized by selection according to zeta potential.

### Claim 19 (depends on 18)

The foam of claim 18, wherein the polyelectrolyte material comprises at least one of polyethyleneimine, polyallylamine, chitosan and dextran sulfate.

### Claim 20 (depends on 13)

The foam of claim 13, further comprising a pH adjusting agent in an effective amount to adjust pH of the foam to a value ranging from 5 to 9.