Claims
- 1. A method of treating a subterranean formation penetrated by a borehole, wherein the static temperature of the borehole adjacent said formation is within the range of from about 50.degree. F. to about 125.degree. F., comprising: injecting into the borehole and into contact with the formation, a water-based fluid, of from between about 7 to about 12 pH and comprising
- (a) an aqueous liquid,
- (b) as a thickening agent to increase the viscosity of the aqueous liquid, a viscosity increasing amount of a polysaccharide which is soluble or dispersible in the aqueous liquid, and
- (c) as a breaker to reduce the viscosity of the fluid after said fluid has contacted the formation and after its intended purpose as a viscous fluid has been served, the combination comprising an effective amount of (i) at least a partially water soluble tertiary amine of a pK.sub.b of from about 3 to about 9, and (ii) at least one compound selected from the group consisting of ammonium persulfates and alkali metal persulfates in at least partially water soluble form.
- 2. The method of claim 1 wherein the treatment is a fracturing treatment, and wherein said injection step is carried out at a rate and pressure sufficient to fracture said formation.
- 3. The method of claim 2 using a tertiary amine of from about 2 to about 7 pK.sub.b.
- 4. The method of claim 3 wherein said water-based fluid contains, per 1000 gallons of fluid, from about 20 to about 100 pounds of said thickening agent, from about 1/10 to about 5 gallons of tertiary amine, if liquid, and if solid, from about 1 to about 40 pounds, and from about 1/4 to 20 pounds of persulfate.
- 5. The method of claim 4 wherein the pH of said water-based fluid is from about 8 to about 11, the pK.sub.b of the amine from about 3 to about 5, said breaker being present in an amount effective to promote a complete break of said fluid in less than about 8 hours following the introduction of the last component of the breaker into the fluid.
- 6. The method of claim 5 wherein the water-based fluid contains, per 1000 gallons of said fluid, from about 1/2 to about 5 gallons of tertiary amine, if liquid, or if solid, from about 4 to about 40 pounds, and about 1/2 to about 10 pounds of persulfate.
- 7. The method of claim 6 wherein the thickening agent is selected from the class consisting of galactomannans, modified and derivative galactomannans and cellulose derivatives.
- 8. The method of claim 7 wherein the fluid contains per 1000 gallons, about 40 to about 60 pounds of crosslinked thickening agent.
- 9. The method of claim 8 wherein the thickening agent is guar or hydroxypropyl guar.
- 10. The method of claim 9 using in said breaker, ammonium persulfate.
- 11. A method for reducing the viscosity of a viscous water-based fluid at temperatures of from about 50.degree. F. to about 125.degree. F., said fluid containing a viscosity-increasing amount of a water soluble or dispersible polysaccharide, and comprising: providing in said fluid, a breaker to reduce the viscosity of the fluid which comprises an effective amount of (i) a tertiary amine of a pK.sub.b of from about 2 to about 9, and (ii) at least one compound selected from the group consisting of ammonium persulfate, and alkali metal persulfates in at least partially water soluble form.
- 12. The method of claim 11 using a tertiary amine of from about 2 to about 7 pK.sub.b.
- 13. The method of claim 12 wherein the polysaccharide is selected from the class consisting of galactomannans and modified and derivative galactomannans, and cellulose derivatives.
- 14. The method of claim 13 wherein said water-based fluid contains, per 1000 gallons of fluid, from about 20 to about 100 pounds of thickening agent, from about 1/10 to about 5 gallons of tertiary amine, if liquid, and if solid, from about 1 to about 40 pounds, and from about 1/4 to about 20 pounds persulfate.
- 15. The method of claim 14 wherein the pH of the water-based fluid is from about 8 to about 11, the pK.sub.b of the amine from about 3 to about 5, said breaker being present in an amount effective to promote a complete break of said water-based fluid in less than about 8 hours, following the introduction of the last component of the breaker into the fluid.
- 16. The method of claim 15 wherein the polysaccharide is guar or hydroxypropyl guar in cross-linked form.
- 17. The method of claim 16 wherein the fluid contains, per 1000 gallons, from about 40 to about 60 pounds thickening agent, about 1/2 to about 5 pounds tertiary amine, if liquid, and if solid, from about 4 to 40 pounds, and about 1/2 to about 10 pounds persulfate.
- 18. The method of claim 17 using in said breaker, ammonium persulfate.
- 19. In a water fluid suitable for use in treating subterranean formations at temperatures within the range of from about 50.degree.-125.degree. F. which are penetrated by a well, said fluid being of the type containing
- (a) as a thickening agent to increase the viscosity of the fluid, from about 20 to about 100 pounds per 1000 gallons of said fluid, a water soluble or dispersible polysaccharide, and
- (b) a breaker to reduce the viscosity of the fluid after a period of time, the improvement which comprises: as the breaker an effective amount of (i) a water soluble or at least partially water soluble tertiary amine of a pK.sub.b of from about 2 to about 9, and at least one compound selected from the group consisting of ammonium persulfate, and alkali metal persulfates in at least partially water soluble form.
- 20. The fluid of claim 19 comprising as the breaker, a tertiary amine of a pK.sub.b from about 2 to about 7.
- 21. The fluid of claim 20 wherein the thickening agent is selected from the class consisting of galactomannans, and modified and derivative galactomannans.
- 22. The fluid of claim 21 wherein the fluid contains per 1000 gallons, from about 1/10 to about 5 gallons of tertiary amine, if liquid, and if solid, from about 1 to about 40 pounds, and from about 1/4 to about 20 pounds persulfate.
- 23. The fluid of claim 22 containing a particulate propping agent.
- 24. The fluid of claim 23 containing a tertiary amine of a pK.sub.b of from about 3 to about 5.
- 25. The fluid of claim 24 containing, per 1000 gallons, about 40 to about 60 pounds thickening agent, about 1/2 gallon to about 5 gallons tertiary amine, if liquid, or if solid, about 4 to about 40 pounds, and from about 1/2 pound to 10 pounds persulfate.
- 26. The fluid of claim 25 wherein the thickening agent is guar or hydroxypropyl guar, and said breaker comprises ammonium persulfate.
CROSS-REFERENCE TO RELATED APPLICATIONS
This is an continuation of application Ser. No. 189,454, filed Sept. 22, 1980, now abandoned, which is a continuation of application Ser. No. 919,336, filed June 26, 1978, now U.S. Pat. No. 4,250,044.
US Referenced Citations (6)
Continuations (2)
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Number |
Date |
Country |
Parent |
189454 |
Sep 1980 |
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Parent |
919336 |
Jun 1978 |
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