CA2561814A1

CA2561814A1 - Viscoelastic surfactant rheology modification

Info

Publication number: CA2561814A1
Application number: CA 2561814
Authority: CA
Inventors: Yiyan Chen; Carlos Abad
Original assignee: Schlumberger Canada Ltd
Current assignee: Schlumberger Canada Ltd
Priority date: 2005-10-13
Filing date: 2006-10-02
Publication date: 2007-04-13
Anticipated expiration: 2026-10-02
Also published as: CA2561814C

Abstract

A method for shortening the shear recovery time of cationic, zwitterionic, a nd amphoteric viscoelastic surfactant fluid systems by adding an effective amou nt of an amphiphilic polymeric rheology enhancer containing at least one portion that is a partially hydrolyzed polyvinyl ester or partially hydrolyzed polyacrylate. T he rheology enhancer also increases fluid viscosity and very low rheology enhancer concentration is needed. Preferred surfactants are betaines and quaternary amines. The fluids are useful in oilfield treatments, for example fracturing and gravel packing.

Claims

1. An oilfield treatment method comprising:
a. providing a fluid comprising a viscoelastic surfactant selected from the group consisting of zwitterionic, amphoteric, and cationic surfactants and mixtures thereof, b. adding to the fluid a rheology enhancer in a concentration sufficient to shorten the shear recovery time of said fluid, said rheology enhancer being a polymer comprising at least one portion selected from the group consisting of partially hydrolyzed polyvinyl esters, partially hydrolyzed polyacrylates, and sulfonate-containing polymers; and c. injecting said fluid down a well.

2. The method of claim 1 further wherein said rheology enhancer increases the viscosity of said fluid.

3. The method of claim 1 wherein said viscoelastic surfactant comprises a zwitterionic surfactant.

4. The method of claim 1 wherein said zwitterionic surfactant comprises a surfactant or mixture of surfactants having the formula:

RCONH-(CH2)a(CH2CH2O)m(CH2)b-N+(CH3)2-(CH2)a'(CH2CH2O)m'(CH2)b'COO-wherein R is an alkyl group that contains from about 17 to about 23 carbon atoms which may be branched or straight chained and which may be saturated or unsaturated; a, b, a', and b' are each from 0 to 10 and m and m' are each from to 13, a and b are each 1 or 2 if m is not 0 and (a + b) is from 2 to 10 if m is 0; a' and b' are each 1 or 2 when m' is not 0 and (a' + b') is from 1 to 5 if m' is 0; (m + m') is from 0 to 14; and CH2CH2O may also be OCH2CH2.

5. The method of claim 1 wherein said zwitterionic surfactant has the betaine structure:

wherein R is a hydrocarbon group that may be branched or straight chained, aromatic, aliphatic or olefinic and has from about 14 to about 26 carbon atoms and may contain an amine; n = about 2 to about 4; and p = 1 to about 5, and mixtures of these compounds.

6. The method of claim 5 wherein said betaine comprises oleylamidopropyl betaine.

7. The method of claim 5 wherein said betaine comprises erucylamidopropyl betaine.

8. The method of claim 5 wherein said fluid further comprises a co-surfactant.

9. The method of claim 1 wherein said viscoelastic surfactant comprises a cationic surfactant.

10. The method of claim 9 wherein said cationic surfactant comprises a surfactant or mixture of surfactants having the structure:
R1N+(R2)(R3)(R4) X-in which R1 has from about 14 to about 26 carbon atoms and may be branched or straight chained, aromatic, saturated or unsaturated, and may comprise a carbonyl, an amide, a retroamide, an imide, a urea, or an amine; R2, R3, and are each independently hydrogen or a C1 to about C6 aliphatic group which may be the same or different, branched or straight chained, saturated or unsaturated and one or more than one of which may be substituted with a group that renders the R2, R3, and R4 group more hydrophilic; the R2, R3 and R4 groups may be incorporated into a heterocyclic 5- or 6-member ring structure which includes the nitrogen atom; the R2, R3 and R4 groups may be the same or different; R1, R2, R3 and/or R4 may contain one or more ethylene oxide and/or propylene oxide units; and X- is an anion; and mixtures of these compounds.

11. The method of claim 10 wherein R1 comprises from about 18 to about 22 carbon atoms and may comprise a carbonyl, an amide, or an amine; R2 , R3, and R4 comprise from 1 to about 3 carbon atoms, and X- is a halide.

12. The method of claim 11 wherein R1 comprises from about 18 to about 22 carbon atoms and may comprise a carbonyl, an amide, or an amine, and R2 , R3. and R4 are the same as one another and comprise from 1 to about 3 carbon atoms.

13. The method of claim 1 wherein said fluid further comprises a member selected from the group consisting of amines, alcohols, glycols, organic salts, chelating agents, solvents, mutual solvents, organic acids, organic acid salts, inorganic salts, oligomers, and mixtures of said members.

14. The method of claim 13 wherein said member is present at a concentration of between about 0.01 and about 10 percent.

15. The method of claim 13 wherein said member is present at a concentration of between about 0.01 and about 1 percent.

16. The method of claim 1 wherein said amphoteric surfactant comprises an amine oxide.

17. The method of claim 16 wherein said amine oxide comprises an amidoamine oxide

18. The method of claim 1 wherein said rheology enhancer is present in said fluid at a concentration of from about 0.0001% to about 0.5%.

19. The method of claim 18 wherein said rheology enhancer is present in said fluid at a concentration of from about 0.0001% to about 0.05%.

20. The method of claim 1 wherein said rheology enhancer comprises a copolymer comprising at least one portion comprising partially hydrolyzed polyvinyl acetate having a percent hydrolysis between about 10% and about 95%.

21. The method of claim 20 wherein said rheology enhancer comprises partially hydrolyzed polyvinyl acetate having a molecular weight of from about 500 to about 100,000,000.

22. The method of claim 20 wherein said rheology enhancer comprises partially hydrolyzed polyvinyl acetate having a percent hydrolysis between about 30% and about 88%.

23. The method of claim 22 wherein said rheology enhancer comprises partially hydrolyzed polyvinyl acetate having a molecular weight of from about 500 to about 100,000,000.

24. The method of claim 1 wherein said rheology enhancer comprises a copolymer comprising at least one portion comprising selected from the group consisting of partially hydrolyzed polyacrylates, and partially hydrolyzed polymethacrylates, and mixtures thereof.

25. The method of claim 24 wherein said partially hydrolyzed polyacrylate and partially hydrolyzed polymethacrylate is selected from the group consisting of partially hydrolyzed polymethyl acrylate, partially hydrolyzed polyethyl acrylate, partially hydrolyzed polybutyl acrylate, partially hydrolyzed polymethyl methacrylate, and mixtures thereof.

26. The method of claim 1 wherein said partially hydrolyzed polyvinyl ester is selected from the group consisting of partially hydrolyzed C1 to C11 esters of polyvinyl alcohol.

27. The method of claim 1 wherein said fluid further comprises an acid selected from the group consisting of hydrochloric acid, hydrofluoric acid, formic acid, acetic acid, polylactic acid, polyglycolic acid, lactic acid, glycolic acid, sulfamic acid, malic acid, citric acid, tartaric acid, maleic acid, methylsulfamic acid, chloroacetic acid, and mixtures thereof.

28. The method of claim 1 wherein said theology enhancer comprises an amphiphilic non-linear polymer having a structure selected from star, comb, dendritic, brush, graft, and star-branched.

29. The method of claim 1 wherein said theology enhancer comprises a polymer having at least one portion comprising polyethylene oxide, polypropylene oxide, and mixtures thereof.

30. The method of claim 1 wherein said theology enhancer comprises a copolymer selected from the group consisting of random, alternating, and block copolymers.

31. A method of shortening the shear recovery time of a viscoelastic surfactant based fluid comprising:
a. providing a fluid comprising a viscoelastic surfactant selected from the group consisting of zwitterionic, amphoteric, and cationic surfactants and mixtures thereof; and b adding to the fluid a theology enhancer in a concentration sufficient to shorten the shear recovery time of said fluid, said theology enhancer being a polymer comprising at least one portion selected from the group consisting of partially hydrolyzed polyvinyl esters, partially hydrolyzed polyacrylates, and sulfonate-containing polymers.

32. A composition comprising a viscoelastic surfactant selected from the group consisting of zwitterionic, amphoteric, and cationic surfactants and mixtures thereof; and a theology enhancer in a concentration sufficient to shorten the shear recovery time of said fluid, said theology enhancer being a polymer comprising at least one portion selected from the group consisting of partially hydrolyzed polyvinyl esters, partially hydrolyzed polyacrylates, and sulfonate-containing polymers.