# US 2014/0196897 A1 · Oxidative internal breaker system with breaking activators for viscoelastic surfactant fluids

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- Number: US 2014/0196897 A1
- Document ID: US20140196897A1
- Status: Published application
- Kind: A1
- Application number: 13/911,612
- Filed: 2013-06-06
- Published: 2014-07-17
- Earliest claimed: 2006-09-18
- Assignees: Schlumberger Technology Corporation
- Applicants: Schlumberger Technology Corporation
- Inventors: Lijun Lin; Carlos Abad; Belgin Baser; Leiming Li
- Web page: https://patentgrep.com/patent/US20140196897A1

## CPC

- C09K 8/584: characterised by the use of specific surfactants
- C09K 8/68: containing organic compounds
- C09K 8/706: {Encapsulated breakers}
- C09K 8/74: combined with additives added for specific purposes
- C09K 2208/26: Gel breakers other than bacteria or enzymes
- C09K 2208/30: Viscoelastic surfactants [VES]
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE

## Abstract

Compositions and methods are given for delayed breaking of viscoelastic surfactant gels inside formation pores, particularly for use in hydraulic fracturing. Breaking inside formation pores is accomplished without mechanical intervention or use of a second fluid. Bromate oxidizing agents are used along with selected breaking activators for the bromate breaking compounds. Useful bromate breaking activators include acid-generating breaking activators, oxidizing sulfur containing breaking activators, and reducing agent breaking activators.

## Claims

### Claim at position 1

1-15. (canceled)

### Claim 16

A method of treating a subterranean formation penetrated by a wellbore comprising a) injecting into the pores of the formation an aqueous gel comprising a non-polymeric viscosifier, a bromate oxidizing agent soluble in the gel, and a breaking activator for said bromate oxidizing agent, and b) allowing said gel to lose viscosity in the pores after the injection wherein said breaking activator is selected from the group consisting of sodium thiosulfate, glutaraldehyde, sodium persulfate, sodium tetrathionate, glucose, sodium bisulfate, and sodium metabisulfite; and
wherein the aqueous gel exhibits a decrease in viscosity at temperatures lower than exhibited in the absence of a breaking activator.

### Claim at position 3

17-19. (canceled)

### Claim 20 (depends on 16)

The method of claim 16 wherein said breaking activator is glucose.

### Claim 21

(canceled)

### Claim 22 (depends on 16)

The method of claim 16 wherein said oxidizing agent comprises sodium bromate or potassium bromate.

### Claim 23 (depends on 16)

The method of claim 16 wherein said fluid includes a brine selected from the group consisting of NaBr, KCl, NaCl, CaBr2, and CaCl2.

### Claim at position 8

24-35. (canceled)

### Claim 36 (depends on 16)

The method of claim 16 wherein the aqueous gel further comprises a free radical propagating agent.

### Claim 37 (depends on 36)

The method of claim 36 wherein said free radical propagating agent is selected from the group consisting of ferrous ion, metabisulfites, reducing sugars, and reducing di-, tri-, oligo- and poly-saccharides.

### Claim 38 (depends on 16)

The method of claim 16 wherein the non-polymeric viscosifier comprises a viscoelastic surfactant

### Claim 39 (depends on 38)

The method of claim 38 wherein the viscoelastic surfactant comprises a zwitterionic surfactant.

### Claim 40 (depends on 39)

The method of claim 39 wherein said zwitterionic surfactant comprises a betaine.

### Claim 41 (depends on 38)

The method of claim 38 wherein said viscoelastic surfactant comprises an amine oxide surfactant.

### Claim 42 (depends on 38)

The method of claim 38 wherein said viscoelastic surfactant comprises a partially saturated hydrophobic chain.

### Claim 43 (depends on 16)

The method of claim 16 wherein the breaking activator is sodium thiosulfate, sodium persulfate, sodium bisulfate, sodium metabisulfite, or combinations thereof.

### Claim 44 (depends on 16)

The method of claim 16 wherein the breaking activator is glutaraldehyde, glucose or combinations thereof.