# US 11,441,066 B2 · Polymer dispersions for oilfield friction reduction

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- Number: US 11,441,066 B2
- Document ID: US11441066B2
- Status: Granted
- Kind: B2
- Application number: 17/099,955
- Filed: 2020-11-17
- Published: 2021-06-03
- Granted: 2022-09-13
- Earliest claimed: 2019-12-02
- Assignees: Solvay USA Inc.
- Applicants: Solvay USA Inc.
- Inventors: Qing Wang; Genyao Lin; Zhihua Zhang; Fulya Sudur Zalluhoglu
- Web page: https://patentgrep.com/patent/US11441066B2

## CPC

- C09K 8/03: Specific additives for general use in well-drilling compositions
- C09K 8/604: {Polymeric surfactants}
- C09K 8/68: containing organic compounds
- E21B 43/26: by forming crevices or fractures
- 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

## Abstract

A polymer dispersion includes a water-soluble copolymer prepared by controlled radical polymerization; a water soluble salt; a polyol; a salt selected from the group consisting of sodium citrate, sodium phosphate, sodium nitrate, and combinations thereof; and water. Methods for using the polymer dispersion for oilfield friction reduction occur under a variety of adverse conditions including low temperatures, salt, scale, and iron.

## Claims

### Claim 1

A polymer dispersion comprising:
a) 2 to 30 weight percentage of a water soluble copolymer;
b) 10 to 50 weight percentage of a water soluble salt;
c) 0 to 20 weight percentage of a polyol;
d) a salt selected from the group consisting of sodium citrate, sodium phosphate, sodium nitrate, and combinations thereof; and
e) water;
weight percentages are based on total weight of the polymer dispersion; wherein said copolymer is obtained by a process comprising the steps of:
(A) an ionic charged polymeric dispersant is prepared from at least an ionic monomer in the presence of a radical polymerization control agent to obtain a living polymer,
(B), said living polymer is charged into an aqueous solution comprising a nonionic monomer, and optionally an ionic monomer, the aqueous solution is then subject to continuous polymerization to obtain said copolymer.

### Claim 2 (depends on 1)

The polymer dispersion according to claim 1, wherein said radical polymerization control agent is a compound bearing a thiocarbonylthio group —S(C═S)—.

### Claim 3 (depends on 1)

The polymer dispersion according to claim 1, wherein said radical polymerization control agent is a compound chosen from the group consisting of xanthate, trithiocarbonate, dithiocarbamate and dithiocarbazate.

### Claim 4 (depends on 1)

A method for reducing friction resulting from turbulent flow in an aqueous fracturing fluid in an oil field fracturing process comprising adding to the aqueous fracturing fluid an effective friction-reducing amount of the polymer dispersion according to claim 1.

### Claim 5 (depends on 1)

A method for fracturing a subterranean formation, the method comprising the step of injecting an aqueous fracturing fluid comprising the polymer dispersion of claim 1 into at least a portion of the subterranean formation at pressures sufficient to fracture the formation.

### Claim 6 (depends on 5)

The method of claim 5, wherein the fracturing fluid is selected from the group consisting of fresh water, sea water, brines, salt water, produced water, recycled water, industrial waste water, waste water associated with oil production, and combinations thereof.

### Claim 7 (depends on 5)

The method of claim 5, wherein the salt is selected from the group consisting of sodium citrate, sodium phosphate, and combinations thereof and the aqueous fracturing fluid comprises iron ion dissolved in the fluid.

### Claim 8 (depends on 5)

The method of claim 5, wherein the salt is selected from the group consisting of sodium citrate, sodium phosphate, and combinations thereof and the aqueous fracturing fluid comprises one or more divalent cations dissolved in the fluid.

### Claim 9 (depends on 5)

The method of claim 5, wherein the salt is selected from the group consisting of sodium nitrate, potassium formate, ammonium chloride, and combinations thereof and comprises a polyol.