Well treatment fluids containing an ylide or a vitamin B and methods of using the same
View Patent ↗Viscosifying polymers are effectively degraded during a well treatment operation with an ylide breaker or a vitamin B cofactor. The vitamin B cofactor is an ylide, vitamin B 1 , vitamin B 2 , vitamin B 3 , vitamin B 6 , vitamin B 9 or vitamin B 12 or mixtures thereof. Such breakers are effective at room and elevated temperatures and high pH environments.
1. An aqueous fracturing fluid comprising:
(a) a viscosifying polymer; and
(b) a breaker comprising an ylide or a vitamin B cofactor selected from the group consisting of vitamin B 1 , vitamin B 2 , vitamin B 3 , vitamin B 6 , vitamin B 9 , vitamin B 12 , and mixtures thereof
wherein the pH of the aqueous fracturing fluid is greater than or equal to 8.0.
2. The aqueous fracturing fluid of claim 1 , wherein the breaker is selected from the group consisting of vitamin B 1 , vitamin B 2 , vitamin B 12 , and mixtures thereof.
3. The aqueous fracturing fluid of claim 1 , wherein the breaker is an ylide.
4. The aqueous fracturing fluid of claim 3 , wherein the breaker is vitamin B 1 .
5. The aqueous fracturing fluid of claim 3 , wherein the breaker is an ylide of phosphorus, sulfur, oxygen, nitrogen or halogen.
6. The aqueous fracturing fluid of claim 1 , wherein the viscosifying polymer is (i) a synthetic polymer selected from the group consisting of polyvinyl alcohols, polyacrylates, polypyrrolidones and polyacrylamides; or (ii) a polysaccharide selected from the group consisting of cellulosic derivatives, galactomannan or a galactomannan derivative, xanthan, succinoglycan and scleroglucan; and mixtures thereof.
7. The aqueous fracturing fluid of claim 6 , wherein the polysaccharide is a cellulosic derivative selected from the group consisting of hydroxyalkyl celluloses, alkylcarboxyhydroxy celluloses and carboxyalkyl cellulose derivatives.
8. The aqueous fracturing fluid of claim 7 , wherein the cellulosic derivative is selected from the group consisting of hydroxyethyl cellulose, methylhydroxyethyl cellulose, ethylhydroxyethyl cellulose, carboxymethylhydroxyethyl cellulose and methylhydroxypropyl cellulose.
9. The aqueous fracturing fluid of claim 6 , wherein the polysaccharide is selected from the group consisting of guar gum, hydroxypropylguar, carboxymethylguar, carboxymethylhydroxypropylguar, xanthan gum and scleroglucan.
10. The aqueous fracturing fluid of claim 1 , further comprising a crosslinking agent.
11. The aqueous fracturing fluid of claim 10 , wherein the crosslinking agent is a borate ion releasing compound or an organometallic containing either zirconium or titanium.
12. The aqueous fracturing fluid of claim 10 , wherein the pH of the fluid is greater than or equal to 9.0.
13. The aqueous fracturing fluid of claim 1 , further comprising an enzyme.
14. A method of fracturing a subterranean formation penetrated by a wellbore, the method comprising the steps of:
(a) injecting the aqueous fracturing fluid of claim 1 into the wellbore at a pressure sufficient to create or enlarge a fracture in the subterranean formation;
(b) reducing the viscosity of the fluid at an elevated temperature by allowing the breaker to degrade the viscosifying polymer; and
(c) removing the degraded viscosifying polymer from the subterranean formation.
15. The method of claim 14 , wherein the breaker is thermally stable at a temperature of at least 75° F.
16. The method of claim 14 , wherein the aqueous fracturing fluid is slickwater.
17. The method of claim 14 , wherein the breaker is selected from the group consisting of vitamin B 1 , vitamin B 2 and vitamin B 12 and mixtures thereof.
18. The method of claim 14 , wherein the viscosifying polymer is (i) a synthetic polymer selected from the group consisting of polyvinyl alcohols, polyacrylates, polypyrrolidones and polyacrylamides; or (ii) a polysaccharide selected from the group consisting of cellulosic derivatives, galactomannan or a galactomannan derivative, xanthan, succinoglycan and scleroglucan; and mixtures thereof.
19. The method of claim 18 , wherein the fluid further comprises a crosslinking agent.
20. The method of claim 19 , wherein the viscosifying polymer is galactomannan or a galactomannan derivative.
21. The method of claim 20 , wherein the viscosifying polymer is selected from the group consisting of guar, carboxymethyl guar, hydroxypropylguar and carboxymethylhydroxypropylguar.
22. A method of fracturing a subterranean formation penetrated by a wellbore which comprises introducing into the subterranean formation the aqueous fracturing fluid of claim 1 at a pressure sufficient to enlarge or create a fracture.
23. The method of claim 22 , wherein the breaker is selected from the group consisting of vitamin B 1 , vitamin B 2 , vitamin B 12 , and mixtures thereof.