Composition for enhanced fracture cleanup using redox treatment

Patent metadata

Field	Value
Publication number	US-9963631-B2
Application number	US-201615162831-A
Country	US
Kind code	B2
Filing date	May 24, 2016
Priority date	Apr 17, 2014
Publication date	May 8, 2018
Grant date	May 8, 2018

Abstract

A composition for improved hydrocarbon recovery from a formation due to cleanup of a residual viscous material is provided. The composition comprises an acid precursor, the acid precursor operable to trigger an exothermic reaction component; and the exothermic reaction component operable to generate heat, where the heat is operable to reduce a viscosity of the residual viscous material to create a reduced viscosity material, the reduced viscosity material operable to flow from the fractures.

First claim

What is claimed is:

1. A cleanup fluid for reducing a viscosity of a residual viscous material in fractures of a hydrocarbon-bearing reservoir, the cleanup fluid comprising:
an optional acid precursor, the optional acid precursor present only at a concentration to be consumed, if present, while triggering an exothermic reaction component in addition to or alternative to heat in the wellbore, and the optional acid precursor comprising at least one component selected from the group consisting of: triacetin; methyl acetate; hydrochloric acid; acetic acid; and mixtures thereof; and
the exothermic reaction component operable to generate heat, and the exothermic reaction component comprising at least one component selected from the group consisting of: urea;
sodium hypochlorite; ammonium chloride; ammonium bromide; ammonium nitrate;
ammonium sulfate; ammonium carbonate; ammonium hydroxide; sodium nitrite; potassium nitrite; and mixtures thereof, and the exothermic reaction component comprising at least one ammonium containing compound at about 3 molar (M) concentration and at least one nitrite containing compound at about 3 molar (M) concentration,
where the cleanup fluid comprises only liquid components in solution prepared to be fluidly compatible with a viscous fluid component such that the cleanup fluid and viscous fluid component quickly mix and the heat reduces a viscosity of the viscous fluid component to create a reduced viscosity material in less than about 1 minute,
where the cleanup fluid does not include viscosifying components at concentrations that generate foam or introduce foam into the fractures of the hydrocarbon-bearing reservoir.

2. The cleanup fluid of claim 1 , where the ammonium containing compound comprises NH 4 Cl and the nitrite containing compound comprises NaNO 2 .

3. The cleanup fluid of claim 1 , including the optional acid precursor, where the optional acid precursor comprises triacetin.

4. The cleanup fluid of claim 1 , further comprising a base to initially increase pH of the cleanup fluid.

5. The cleanup fluid of claim 1 , where the cleanup fluid reduces the viscosity of the residual viscous material to the reduced viscosity, the reduced viscosity being about 1/10 of the viscosity of the residual viscous material.

6. The cleanup fluid of claim 1 , where the exothermic reaction component is triggered at greater than about 120° F. in the fractures.

7. The cleanup fluid of claim 1 , where the exothermic reaction component is triggered at a pH less than about 6 in the fractures.

8. The cleanup fluid of claim 1 , where the exothermic reaction component is triggered at greater than about 120° F. while the pH of the cleanup fluid is less than about 6 in the fractures.

9. The cleanup fluid of claim 1 , where the ammonium containing compound is selected from the group consisting of: ammonium chloride; ammonium bromide; ammonium nitrate; ammonium sulfate; ammonium carbonate; ammonium hydroxide; and mixtures thereof.

10. The cleanup fluid of claim 1 , where the nitrite containing compound is selected from the group consisting of: sodium nitrite; potassium nitrite; and mixtures thereof.

11. The cleanup fluid of claim 1 , further comprising the viscous fluid component.

12. The cleanup fluid of claim 11 , where the viscous fluid component is selected from the group consisting of: carboxymethyl cellulose; hydroxyethyl cellulose; carboxymethyl hydroxyethyl cellulose; hydroxypropyl cellulose; methyl hydroxyl ethyl cellulose; and mixtures thereof.

13. The cleanup fluid of claim 11 , where the viscous fluid component is selected from the group consisting of: hydroxypropyl guar; carboxymethyl guar; guar cross-linked boron ions from an aqueous borax/boric acid solution; guar cross-linked with organometallic compounds; and mixtures thereof.

14. The cleanup fluid of claim 1 , further comprising a viscous carrier fluid.

15. The cleanup fluid of claim 1 , further comprising a fracturing fluid.

Assignees

• Saudi Arabian Oil Co

Inventors

• Al-Nakhli Ayman R
• Abass Hazim H
• Al-Otaibi Ahmad S

Classifications

• C09K8/592

  Compositions used in combination with generated heat, e.g. by steam injection · CPC title

• C09K8/52 Primary

  Compositions for preventing, limiting or eliminating depositions, e.g. for cleaning · CPC title

• E21B43/267

  reinforcing fractures by propping · CPC title

• C09K8/62

  Compositions for forming crevices or fractures · CPC title

• E21B43/26

  by forming crevices or fractures · CPC title