# US 12,215,276 B2 · Ph control in fluid treatment

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- Number: US 12,215,276 B2
- Document ID: US12215276B2
- Status: Granted
- Kind: B2
- Application number: 18/160,710
- Filed: 2023-01-27
- Published: 2023-10-12
- Granted: 2025-02-04
- Earliest claimed: 2018-10-22
- Assignees: Chevron U.S.A. Inc.
- Applicants: Chevron U.S.A. Inc.
- Inventors: Sujeewa S. Palayangoda; Kerry Kennedy Spilker; Sumitra Subrahmanyan; Gayani W. Pinnawala; Sophany Thach; Gregory A. Winslow; Dennis Arun Alexis; Harold Charles Linnemeyer; Timothy P. Theriot; Les Leszek Jackowski; Francesca Cibotti
- Web page: https://patentgrep.com/patent/US12215276B2

## CPC

- C09K 8/588: characterised by the use of specific polymers {(polymeric surfactants C09K8/584)}
- C09K 8/032: {Inorganic additives}
- E21B 21/068: {using chemical treatment}
- E21B 43/385: {by reinjecting the separated materials into an earth formation in the same well}
- C02F 1/24: by flotation (C02F1/465 takes precedence)
- C02F 1/38: by centrifugal separation
- C02F 1/72: by oxidation {(C02F1/4672 takes precedence)}
- C02F 2101/30: Organic compounds
- C02F 2101/32: Hydrocarbons, e.g. oil
- C02F 2303/18: Removal of treatment agents after treatment
- C09K 2208/26: Gel breakers other than bacteria or enzymes
- C09K 2208/28: Friction or drag reducing additives
- 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
- C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes)

## Abstract

Described herein are methods of treating fluid including hydrocarbons, water, and polymer being produced from a hydrocarbon-bearing formation. The methods include adding a concentration of a viscosity reducer to the fluid to degrade the polymer present in the fluid and adding a concentration of a neutralizer to the fluid to neutralize the viscosity reducer in the fluid. The viscosity reducer is buffered at a pH of 7 or less. The addition of the concentration of the viscosity reducer is in a sufficient quantity to allow for complete chemical degradation of the polymer prior to the addition of the concentration of the neutralizer in the fluid such that excess viscosity reducer is present in the fluid.

## Claims

### Claim 1

A system of treating fluid, the system comprising:
a production wellbore for producing fluid comprising hydrocarbons, water, and polymer from a hydrocarbon-bearing formation;
a first injection apparatus for adding a concentration of a viscosity reducer to the fluid to degrade the polymer present in the fluid;
a second injection apparatus for adding a concentration of a neutralizer to the fluid to neutralize the viscosity reducer in the fluid; and
surface fluid processing equipment for separating the hydrocarbons from the fluid; wherein:
a pH of the viscosity reducer is lowered to a pH of 7 or less;
the addition of the concentration of the viscosity reducer is in a sufficient quantity to allow for complete chemical degradation of the polymer prior to the addition of the concentration of the neutralizer in the fluid such that excess viscosity reducer is present in the fluid; and
the addition of the concentration of the neutralizer is sufficiently upstream of any of the surface fluid processing equipment to allow for complete neutralization of the excess viscosity reducer such that excess neutralizer is present in the fluid prior to the fluid reaching any of the surface fluid processing equipment,
wherein the concentration of the viscosity reducer is added at a first location, and wherein the concentration of the neutralizer is added at a second location.

### Claim 2 (depends on 1)

The system of claim 1, wherein the fluid is passed through the surface fluid processing equipment to separate the hydrocarbons and the water, and wherein a concentration of additional polymer is added to the separated water to increase the viscosity of the separated water, and
wherein the separated water with the increased viscosity is injected into the hydrocarbon-bearing formation, a different hydrocarbon-bearing formation, or any combination thereof.

### Claim 3 (depends on 1)

The system of claim 1, wherein the surface fluid processing equipment comprises a free water knockout, a heat exchanger, a separator, a flotation cell, an induced gas flotation apparatus, a hydrocyclone, a filter, or any combination thereof.

### Claim 4 (depends on 3)

The system of claim 3, wherein the surface fluid processing equipment comprises the heat exchanger and wherein at least a portion of the heat exchanger is coated with a coating to reduce polymer adherence.

### Claim 5 (depends on 4)

The system of claim 4, wherein the coating has a thickness of from 5 microns to 120 microns.

### Claim 6 (depends on 4)

The system of claim 4, wherein the coating comprises from one to three layers.

### Claim 7 (depends on 4)

The system of claim 4, wherein the coating comprises an organic-inorganic hybrid coating, a fluoropolymer coating, or any combination thereof.

### Claim 8 (depends on 1)

The system of claim 1, wherein the first location is prior to any downhole fluid lifting equipment in the production wellbore.

### Claim 9 (depends on 8)

The system of claim 8, wherein the downhole fluid lifting equipment comprises an electronic submersible pump, a hydraulic submersible pump, gas lift equipment, or any combination thereof.

### Claim 10 (depends on 9)

The system of claim 9, wherein the downhole fluid lifting equipment comprises the electric submersible pump and wherein at least a portion of the electric submersible pump is coated with a coating to reduce polymer adherence.

### Claim 11 (depends on 10)

The system of claim 10, wherein the coating has a thickness of from 5 microns to 120 microns.

### Claim 12 (depends on 10)

The system of claim 10, wherein the coating comprises an organic-inorganic hybrid coating, a fluoropolymer coating, or any combination thereof.

### Claim 13 (depends on 1)

The system of claim 1, wherein the first location is downstream of a wellhead of the production wellbore.

### Claim 14 (depends on 1)

The system of claim 1, wherein the surface fluid processing equipment comprises a free water knockout, and the second location is upstream of the free water knockout.

### Claim 15 (depends on 14)

The system of claim 14, wherein the surface fluid processing equipment comprises a heat exchanger downstream of the free water knockout, and the second location is upstream of the free water knockout.

### Claim 16 (depends on 14)

The system of claim 14, wherein the surface fluid processing equipment comprises a flotation cell, an induced gas flotation apparatus, a hydrocyclone, a filter, or any combination thereof downstream of the free water knockout, and the second location is upstream of the free water knockout.

### Claim 17 (depends on 14)

The system of claim 14, wherein the first location and the second location are upstream of the free water knockout.

### Claim 18 (depends on 1)

The system of claim 1, wherein the first location is sufficiently upstream of the second location to allow for complete chemical degradation of the polymer prior to the fluid reaching the second location, and wherein the second location is sufficiently upstream of any of the surface fluid processing equipment to allow for complete neutralization of the excess viscosity reducer in the fluid prior to the fluid reaching any of the surface fluid processing equipment.

### Claim 19 (depends on 1)

The system of claim 1, wherein the concentration of the viscosity reducer and the concentration of the neutralizer are added continuously to the fluid.

### Claim 20 (depends on 1)

The system of claim 1, wherein the fluid has a viscosity of less than 1.4 cp with a minimum viscosity of 0.9 cp after separation of at least some of the hydrocarbons from the fluid by the surface fluid processing equipment.