Viscoelastic wellbore treatment fluid

• US 20040067855A1
• Filed: 10/27/2003
• Published: 04/08/2004
• Est. Priority Date: 08/07/2000
• Status: Active Grant

• Current Assignee: Schlumberger Technology Corporation (SLB)
• Original Assignee: Schlumberger Technology Corporation (SLB)
• Inventors: Jones, Timothy Gareth John, Zhou, Jian, Tustin, Gary John, Hughes, Trevor
• Granted Patent: US 7,670,995 B2
• Time in Patent Office: Days
• US Class Current: 507/200
• CPC Class Codes: C09K 23/00 Use of substances as emulsifying, wetting, dispersing, or foam-producing agents
• CPC Class Codes: C09K 23/14 Derivatives of phosphoric acid
• CPC Class Codes: C09K 23/16 Amines or polyamines
• CPC Class Codes: C09K 8/528 inorganic depositions, e.g. sulfates or carbonates
• CPC Class Codes: C09K 8/62 Compositions for forming crevices or fractures

Abstract

A viscoelastic wellbore treatment fluid comprises an effective amount of an oligomeric surfactant for controlling the viscoelasticity of the fluid.

Claims

1. A viscoelastic wellbore treatment fluid comprising an effective amount of an oligomeric surfactant for controlling the viscoelasticity of the fluid.

2. A treatment fluid according to claim 1, wherein the treatment fluid comprises less than 10 percent by weight of oligomeric surfactant.

3. A treatment fluid according to claim 1 or 2, wherein the viscosity of the treatment fluid is breakable on contact with hydrocarbons so that at 20°

C. the viscosity is reduced by at least 80%.

4. A treatment fluid according to any one of claims 1 to 3, wherein the structure of the oligomeric surfactant is based on linked surfactant monomer subunits, each monomer subunit having the formula (R₁-X)_pZ_m;

where X is a charged head group, R₁ is a C₁₀-C₅₀ organic tail group comprising a C₁₀-C₂₅ straight chain bonded at a terminal atom thereof to X, Z is a counterion, and p and m are integers which ensure that the surfactant monomer subunit is charge neutral.

5. A treatment fluid according to any one of claims 1 to 3, wherein the structure of the oligomeric surfactant is based on linked surfactant monomer subunits, each monomer subunit having the formula R₁—

Y;

where Y is a zwitterionic polar headgroup, and R₁ is a C₁₀-C₅₀ organic tail group comprising a C₁₀-C₂₅ straight chain bonded at a carbon atom thereof to Y.

6. A treatment fluid according to claim 4 or 5, wherein the straight chain is a C₁₅-C₂₄ chain.

7. A treatment fluid according to any one of claims 4 to 6, wherein the tail group comprises only the straight chain.

8. A treatment fluid according to any one of claims 4 to 7, wherein the straight chain is unsaturated.

9. A treatment fluid according to any one of claims 4 to 8, wherein the oligomer is formed from two to five monomer subunits.

10. A treatment fluid according to claim 9, wherein the oligomer is a dimer or a trimer.

11. A treatment fluid according to any one of claims 4 and 6 to 10, wherein X is a carboxylate (—

COO⁻

), sulphate (—

OSO₃⁻

), sulphonate (—

SO₃⁻

), phosphate (—

OPO₃²⁻

), or a phosphonate (—

PO₃²) charged group.

12. A treatment fluid according to claim 11, wherein Z is an alkali metal counterion.

13. A treatment fluid according to claim 11 or 12, wherein the surfactant monomer subunit is a salt of oleic acid.

14. A treatment fluid according to any one of claims 4 and 6 to 10, wherein X is a quaternary ammonium (—

NR₂R₃R₄⁺) charged group;

R₂, R₃ and R₄ being C₁-C₆ aliphatic groups, or one of R₂, R₃ and R₄ being a C₁-C₆ aliphatic group and the others of R₂, R₃ and R₄ forming a five- or six-member heterocylic ring with the nitrogen atom.

15. A treatment fluid according to claim 14, wherein the monomer subunits are linked straight chain-to-straight chain in the oligomer.

16. A treatment fluid according claim 14 or 15, wherein R₂, R₃ and R₄ are each and independently a —

CH₃, —

CH₂CH₃, —

CH₂CH₂CH₃, —

CH(CH₃)₂, —

CH₂OH, —

CH₂CH₂OH, —

CH₂CH₂CH₂OH, —

CH₂CH(OH)CH₃, —

CH(OH)CH₂CH₃, —

CH(CH₂OH)CH₃ or —

C(CH₃)₂OH group.

17. A treatment fluid according to any one of claims 14 to 16, wherein R₁ is an erucyl group or an oleyl group.

18. A treatment fluid according to any one of claims 14 to 17, wherein Z is a halide anion such as Cl⁻

or Br⁻

, or an organic anion with a molecular weight of less than 300, such as salicylate or octyl sulphate.

19. A treatment fluid according to any one of claims 14 to 18, wherein the complete oligomer is defined by the formula (R₁R₂R₃N⁺—

(—

R₅—

N⁺(R₁R₄)—

)_n—

R₅—

N⁺R₁R₂R₃)._(n+2)Z⁻

where n=0, 1, 2 or 3, and R₅ comprises a C₁-C₁₂ aliphatic group or a C₅-C₁₂ aromatic or alicyclic group.

20. A treatment fluid according to claim 19, wherein R₅ is an unbranched C₁, C₂, C₃, C₄, C₅ or C₆ aliphatic chain.

21. A treatment fluid according to claim 20, wherein R₅ is a hydrocarbyl chain.

22. A treatment fluid according to any one of claims 1 to 21, further comprising an effective amount of a monomeric surfactant for controlling the viscoelasticity of the fluid.

23. A treatment fluid according to claim 22, wherein the relative amounts of the oligomeric and monomeric surfactants are adjusted so that the viscosity of the treatment fluid, as measured using a steady shear rheometer at a shear rate of 100 s⁻

1, is at least 10 cP for all temperatures in the range 80 to 260°

F. (26.5 to 126.5°

C.).

24. A treatment fluid according to one of claims 1 to 23, which is a fracturing fluid.

25. A treatment fluid according to one of claims 1 to 23, which is a water shut-off treatment fluid.

26. A treatment fluid according to one of claims 1 to 23, which is a selective acidizing fluid.

27. A treatment fluid according to one of claims 1 to 23, which is a scale dissolver fluid for dissolving scale in a subterranean hydrocarbon-bearing formation, the fluid further comprising an effective amount of a scale dissolver formulation whereby in use formation hydrocarbons act on the surfactant to reduce the viscosity of the fluid so that the fluid selectively invades a hydrocarbon-bearing zone of the formation.

28. A method of dissolving scale in a subterranean formation with at least one hydrocarbon-bearing zone, the method including pumping the scale dissolver fluid of claim 27 through a well bore and into the subterranean formation, the viscosity of the scale dissolver fluid being reduced by formation hydrocarbons so that the fluid selectively invades the hydrocarbon-bearing zone of the well to dissolve scale in the hydrocarbon-bearing zone.

29. A method of injecting a scale dissolver fluid into a subterranean formation with at least one hydrocarbon-bearing zone, the method including the step of pumping the scale dissolver fluid of claim 27 through a well bore and into the subterranean formation.