Methods and compositions for thermal insulation

1. A method for enhancing the thermal insulation of a production tubing or transfer pipe surrounded by at least one annuli, comprising:

(a) adding to the at least one annuli a thermal insulating fluid comprising:

(i) a zwitterionic surfactant;

(ii) an alcohol; and

(iii) a brine;

and

(b) maintaining the fluid in contact with the at least one annuli to at least partially immobilize the fluid.

2. The method of claim 1 , wherein the zwitterionic surfactant is selected from:

(a) betaines of the formula:

R 6 N + (R 2 )(R 3 )(R 4 )(OR 4 ) a COO −

(b) aminocarboxylate derivatives of the formula:

and

(c) amine oxides of the formula:

wherein R 6 is an alkyl, alkylarylalkyl, alkoxyalkyl, alkylaminoalkyl, alkylamidoalkyl or alkylamidoalkoxy group wherein the number of carbon atoms in R 6 is between from about 11 to about 24;

R 2 and R 3 are independently an alkyl, alkenyl, arylalkyl, hydroxyalkyl, carboxyalkyl, alkylene carboxylic or hydroxyalkyl-polyoxyalkylene having from 1 to about 30 carbon atoms;

each R 4 is independently a C 1 -C 4 alkylene group; and

a is from 0 to about 4.

3. The method of claim 2 , wherein R 2 and/or R 3 contain between from about 1 to about 6 carbon atoms.

4. The method of claim 2 , wherein the betaine is of the structural formula:

wherein R 1 is R 9 CONH(CH 2 ) b or R 9 , R 9 is an alkyl group that contains from about 11 to about 24 carbon atoms and b is from 1 to 4.

5. The method of claim 4 , wherein R 9 is a C 11 -C 17 alkyl group.

6. The method of claim 5 , wherein the betaine is selected from the formulae:

7. The method of claim 2 , wherein the zwitterionic surfactant is an aminopropionate of the formulae

wherein X is halogen or hydrogen; R 1 is R 9 CONH(CH 2 ) b or R 9 ; R 9 is an alkyl group that contains from about 11 to about 24 carbon atoms; and b is from 1 to 4.

8. The method of claim 2 , wherein the amine oxide is of the formula:

wherein R 1 is R 9 CONH(CH 2 ) b or R 9 . R 9 is an alkyl group that contains from about 11 to about 24 carbon atoms; and b is from 1 to 4.

9. The method of claim 1 , wherein the density of the brine is greater than 12.5 lb/gal.

10. The method of claim 9 , wherein the density of the brine is greater than 13.0 lb/gal.

11. The method of claim 10 , wherein the density of the brine is greater than 14 lb/gal.

12. The method of claim 11 , wherein the brine is a calcium brine.

13. The method of claim 1 , wherein the alcohol is a polyol selected from a glycerol, glycol or polyglycols or a mixture thereof.

14. The method of claim 13 , wherein the polyol is polyethylene glycol, poly(1,3-propanediol), poly(1,2-propanediol), poly(1,2-butanediol), poly(1,3-butanediol), poly(1,4-butanediol), poly(2,3-butanediol), co-polymers, block polymers or a mixture thereof.

15. The method of claim 1 , wherein the amount of alcohol in the thermal insulating composition is between from about 2 to about 10 volume percent.

16. A method for reducing convection flow velocity in at least one annuli surrounding a production tubing or transfer pipe, comprising:

introducing into the at least one annuli an insulating packer or riser fluid comprising a thermal insulating composition comprising:

(i) a zwitterionic surfactant;

(ii) an alcohol; and

(iii) a brine;

and

maintaining the fluid in the at least one annuli until the convection flow velocity is reduced.

17. The method of claim 16 , wherein the insulating fluid, as a packer fluid, is introduced above the packer in the annulus and, as a riser fluid, is introduced into the riser annulus.

18. The method of claim 16 , wherein the zwitterionic surfactant is selected from:

(a) betaines of the formula:

R 6 N + (R 2 )(R 3 )(R 4 )(OR 4 ) a COO −

(b) aminocarboxylate derivatives of the formula:

(c) amine oxides of the formula:

wherein R 6 is an alkyl, alkylarylalkyl, alkoxyalkyl, alkylaminoalkyl, alkylamidoalkyl or alkylamidoalkoxy group wherein the number of carbon atoms in R 6 is between from about 11 to about 24;

R 2 and R 3 are independently an alkyl, alkenyl, arylalkyl, hydroxyalkyl, carboxyalkyl, alkylene carboxylic or hydroxyalkyl-polyoxyalkylene having from 1 to about 30 carbon atoms;

each R 4 is independently a C 1 -C 4 alkylene group; and

a is from 0 to about 4.

19. The method of claim 18 , wherein R 6 is a C 11 -C 17 alkyl group.

20. The method of claim 19 , wherein R 2 and/or R 3 contain between from about 1 to about 6 carbon atoms.

21. The method of claim 18 , wherein the betaine is of the structural formula

wherein R 1 is R 9 CONH(CH 2 ) b or R 9 ; R 9 is an alkyl group that contains from about 11 to about 24 carbon atoms; and b is from 1 to 4.

22. The method of claim 21 , wherein the betaine is selected from the formulae:

23. The method of claim 18 , wherein the zwitterionic surfactant is an aminopropionate of the formulae

wherein X is halogen or hydrogen; R 1 is R 9 CONH(CH 2 ) b or R 9 ; R 9 is an alkyl group that contains from about 11 to about 24 carbon atoms; and b is from 1 to about 4.

24. The method of claim 18 , wherein the amine oxide is of the formula:

wherein R 1 is R 9 CONH(CH 2 ) b — or R 9 ; R 9 is an alkyl group that contains from about 11 to about 24 carbon atoms; and b is from 1 to about 4.

25. The method of claim 16 , wherein the density of the brine is greater than 12.5 lb/gal.

26. The method of claim 25 , wherein the density of the brine is greater than 13.0 lb/gal.

27. The method of claim 25 , the brine is a calcium brine.

28. The method of claim 16 , wherein the alcohol is a polyol selected from a glycerol, glycol or polyglycols or a mixture thereof.

29. The method of claim 28 , wherein the amount of alcohol in the thermal insulating composition is between from about 2 to about 10 volume percent.