Gel plugs and pigs for pipeline use
View Patent ↗Coacervate gels having excellent shear viscosities and other properties are made with anionic or cationic polymers, a smaller amount of a surfactant having a charge opposite that of the polymer, and a hydrophobic alcohol. The Zeta Potential of the gel is maintained at an absolute value of at least 20. Optional gel promoting additives include betaines and amine oxides. A preferred gel comprises poly diallyl dimethyl ammonium chloride, a lesser amount of sodium lauryl sulfonate, and lauryl alcohol. The gels are particularly useful forming plugs and pigs for separating fluids in pipes.
1. Method of separating two portions of fluid for movement in a pipe comprising placing between said portions of fluid in said pipe an aqueous gel separating pig comprising water and, by weight based on the water, (a) 0.1 % to 5% of an anionic or cationic polymer, (b) a lesser amount but at least 0.01 % of a surfactant having from 8 to 22 carbon atoms and a charge opposite that of said polymer, (c) from 0.001 to 5% of a hydrophobic alcohol, (d) up to 5% of an amphoteric surfactant, and (e) up to 5% of an amine oxide, said gel having a Zeta Potential of an absolute value of at least 20 millivolts.
2. Method of claim 1 including forming an isolated segment of at least one of said portions of fluid by placing an additional aqueous gel pig in said pipe a desired distance from said separating pig, said additional aqueous gel pig comprising water and, by weight based on the water, (a) 0.1 % to 5% of an anionic or cationic polymer, (b) a lesser amount but at least 0.01 % of a surfactant having from 8 to 22 carbon atoms and a charge opposite that of said polymer, (c) from 0.001 to 5% of a hydrophobic alcohol, (d) up to 5% of an amphoteric surfactant, and (e) up to 5% of an amine oxide, said gel having a Zeta Potential of an absolute value of at least 20 millivolts.
3. Method of claim 1 wherein at least one of said portions of fluid is a cleaning fluid.
4. Method of claim 1 wherein at least one of said portions of fluid is a drying fluid.
5. Method of claim 1 wherein at least one of said portions of fluid is a well cementing fluid.
6. Method of claim 1 wherein at least one of said portions of fluid is a hydrocarbon fluid.
7. Method of claim 1 wherein one of said portions of fluid is a gas and the other of said portions of fluid is a liquid.
8. Method of claim 1 further including moving said portions of fluid through said pipe.
9. Method of claim 1 wherein said polymer is a cationic polymer and said hydrophobic alcohol is a linear or branched alkyl alcohol of the general formula C M H 2M+2−N (OH) N , where M is a number from 6–23, and N is 1 when M is 6–12, but where M is 13–23, N may be a number from 1 to 3, said gel including at least one of (a) 0.001% to 5% amine oxide and (b) 0.001% amphoteric surfactant.
10. Method of claim 1 wherein said amine oxide comprises lauryl amine oxide and is present in an amount from 0.001% to 2%.
11. Method of claim 2 further including moving said isolated segment of fluid through said pipe.
12. The method of claim 1 wherein the surfactant comprises an anionic surfactant.
13. The method of claim 1 , wherein polymer comprises a cationic polymer.
14. The method of claim 13 , wherein the cationic polymer comprises diallyl dimethyl ammonium chloride.
15. The method of claim 13 , wherein the anionic surfactant comprises sodium lauryl sulfate.
16. The method of claim 15 , wherein the alcohol comprises lauryl alcohol.
17. The method of claim 16 , wherein the amphoteric surfactant comprises a betaine.
18. The method of claim 17 , wherein the betaine comprises cocamidopropyl betaine.
19. The method of claim 18 , wherein the amine oxide comprises an amine oxide having the general formula R 1 R 2 R 3 NO, where R 1 is an alkyl group of 8–22 carbon atoms, and R 2 and R 3 are independent alkyl groups having from 1 to 4 carbon atoms.
20. The method of claim 1 , wherein the amine oxide comprises an amine oxide having the general formula R 1 R 2 R 3 NO, where R 1 is an alkyl group of 8–22 carbon atoms, and R 2 and R 3 are independent alkyl groups having from 1 to 4 carbon atoms.
21. The method of claim 1 , wherein the alcohol comprises lauryl alcohol.
22. The method of claim 1 , wherein the polymer comprises an anionic polymer.
23. The method of claim 1 , wherein the amphoteric surfactant comprises a betaine.
24. The method of claim 23 , wherein the betaine comprises cocamidopropyl betaine.