Microemulsion flowback aids for oilfield uses

Patent metadata

Field	Value
Publication number	US-11066593-B2
Application number	US-202015931665-A
Country	US
Kind code	B2
Filing date	May 14, 2020
Priority date	Nov 14, 2017
Publication date	Jul 20, 2021
Grant date	Jul 20, 2021

Abstract

Flowback aid mixtures and oil-in-water microemulsions produced by combining an aqueous brine with the flowback aid mixtures are disclosed. The flowback aid mixture comprises an oil, a fatty alcohol ethoxylate, and a quaternized fatty amine ethoxylate. The amount of oil is less than or equal to 12 wt. % based on the amount of flowback aid mixture. The microemulsions have a surface tension at 25° C. less than 30 mN/m and a Z-average particle size as determined by dynamic light scattering at 25° C. of less than or equal to 10 nm. Also disclosed are processes that utilize the flowback aid mixtures. In one process, the mixture is introduced into a subterranean formation and is combined prior to or during its introduction into the formation with a formation brine, process water, or both to give the microemulsion. In one hydraulic fracturing process for recovering gas, oil, or both, a fracturing fluid and the flowback aid are co-injected into a subterranean formation to give the microemulsion.

First claim

I claim:

1. A composition comprising an oil-in-water microemulsion produced by combining an aqueous brine with a flowback aid mixture which comprises:
(a) an oil selected from the group consisting of hydrocarbons, terpenes, and C 6 -C 30 fatty alkyl esters;
(b) a fatty alcohol ethoxylate; and
(c) a quaternized fatty amine ethoxylate;
wherein the aqueous brine comprises naturally occurring formation brine, process water, seawater, or a combination thereof;
wherein the amount of oil is within the range of 1 to 12 wt. % based on the amount of flowback aid mixture, and the microemulsion has a surface tension at 25° C. of less than 30 mN/m and a Z-average particle size as determined by dynamic light scattering at 25° C. of less than or equal to 10 nm.

2. The composition of claim 1 wherein the microemulsion has an interfacial tension at 25° C. against decane of less than or equal to 10 mN/m.

3. The composition of claim 1 wherein the microemulsion has a viscosity less than 50 cP at 25° C.

4. The composition of claim 1 wherein at least 50 wt. % of the microemulsion is the brine.

5. The composition of claim 1 wherein the oil is selected from the group consisting of terpenes and C 6 -C 30 fatty methyl esters.

6. The composition of claim 1 wherein the oil is d-limonene.

7. The composition of claim 1 wherein the fatty alcohol ethoxylate is a C 9 -C 11 alcohol ethoxylate having an average of 3 to 4 EO units.

8. The composition of claim 1 wherein the quaternized fatty amine ethoxylate is a quaternized tallowamine EO ethoxylate having an average of 8 to 20 EO units.

9. The composition of claim 1 wherein the microemulsion further comprises propylene glycol.

10. The composition of claim 1 wherein the brine is seawater.

11. The composition of claim 1 wherein the brine comprises 1 to 2 wt. % KCl.

12. The composition of claim 1 wherein the flowback aid mixture comprises 1 to 12 wt. % of the oil, 30 to 70 wt. % of the fatty alcohol ethoxylate, and 30 to 70 wt. % of the quaternized fatty amine ethoxylate.

13. A composition suitable for use as a flowback aid for oilfield applications, the composition comprising:
(a) an oil selected from the group consisting of hydrocarbons, terpenes, and C 6 -C 30 fatty alkyl esters;
(b) a fatty alcohol ethoxylate; and
(c) a quaternized fatty amine ethoxylate;
wherein the amount of oil is within the range of 1 to 12 wt. % based on the amount of composition, and the composition, when combined with an aqueous brine, provides a microemulsion having a surface tension at 25° C. of less than 30 mN/m and a Z-average particle size as determined by dynamic light scattering at 25° C. of less than or equal to 10 nm; wherein the aqueous brine comprises naturally occurring formation brine, process water, seawater, or a combination thereof.

14. The composition of claim 13 wherein the oil is selected from the group consisting of terpenes and C 6 -C 30 fatty methyl esters.

15. The composition of claim 13 wherein the oil is d-limonene.

16. The composition of claim 13 wherein the fatty alcohol ethoxylate is a C 9 -C 11 alcohol ethoxylate having an average of 3 to 4 EO units.

17. The composition of claim 13 wherein the quaternized fatty amine ethoxylate is a quaternized tallowamine EO ethoxylate having an average of 8 to 20 EO units.

18. The composition of claim 13 further comprising propylene glycol.

19. The composition of claim 13 comprising 1 to 12 wt. % of the oil, 30 to 70 wt. % of the fatty alcohol ethoxylate, and 30 to 70 wt. % of the quaternized fatty amine ethoxylate.

20. A process which comprises introducing into a subterranean formation a flowback aid mixture comprising:
(a) an oil selected from the group consisting of hydrocarbons, terpenes, and C 6 -C 30 fatty alkyl esters;
(b) a fatty alcohol ethoxylate; and
(c) a quaternized fatty amine ethoxylate;

wherein the amount of oil is within the range of 1 to 12 wt. % based on the amount of flowback aid mixture, and the mixture is combined prior to or during its introduction into the formation with a naturally occurring formation brine, process water, seawater, or a combination thereof to give a microemulsion having a surface tension at 25° C. of less than 30 mN/m and a Z-average particle size as determined by dynamic light scattering at 25° C. of less than or equal to 10 nm.

Assignees

• Stepan Co

Inventors

• Hutchison John C

Classifications

• C09K8/602

  containing surfactants · CPC title

• C11D1/835

  Mixtures of non-ionic with cationic compounds · CPC title

• C11D1/72

  Ethers of polyoxyalkylene glycols · CPC title

• C11D3/2093

  Esters; Carbonates · CPC title

• C11D3/188

  Terpenes · CPC title