Claims
- 1. In a set retarded cement composition which is substantially non-thinning at high temperatures comprised of hydraulic cement, sufficient water to form a pumpable slurry, a set retarder and a delayed viscosifying agent which yields viscosity at high temperatures comprised of a treated galactomannan gum, the improvement wherein the delayed viscosifying agent is a galactomannan gum which has been depolymerized and treated with a complexing agent whereby the hydration rate of said depolymerized gum is retarded at temperatures below about 120.degree. F. to 140.degree. F. and at pH levels above about 10 but the hydration rate increases at temperatures above about 120.degree. F. to 140.degree. F., said treated depolymerized galactomannan gum being present in said composition in an amount sufficient to offset the thinning of said composition at temperatures above about 120.degree. F. to 140.degree. F. by the hydration of said gum.
- 2. The composition of claim 1 which is further characterized to include a crosslinking agent for said delayed viscosifying agent.
- 3. The composition of claim 1 wherein said galactomannan gum is selected from the group consisting of carob, tara, locust bean, guar, paloverde, and honey locust gums.
- 4. The composition of claim 1 wherein said galactomannan gum is depolymerized by reaction with an oxidizing agent.
- 5. The composition of claim 1 wherein said complexing agent is selected from the group consisting of potassium pyroantimonate and compounds capable of liberating borate ions when added to water.
- 6. The composition of claim 5 wherein said treated depolymerized galactomannan gum is present in said composition in an amount in the range of from about 0.05% to about 2% by weight of hydraulic cement in said composition.
- 7. The composition of claim 2 wherein said crosslinking agent is present in said composition in an amount in the range of from about 5% to about 15% by weight of treated depolymerized galactomannan gum therein.
- 8. The composition of claim 1 wherein said treated depolymerized galactomannan gum is depolymerized guar gum treated with a borate ion liberating complexing agent whereby said gum contains from about 100 parts to about 4000 parts per million boron by weight of gum, said treated depolymerized guar gum being present in said composition in an amount in the range of from about 0.05% to about 2.0% by weight of hydraulic cement in said composition.
- 9. The composition of claim 8 which is further characterized to include a crosslinking agent comprised of a 1:1:1 by weight heat reacted mixture of zirconium triethanolamine, glycerol and water, said crosslinking agent being present in said composition in an amount in the range of from about 5% to about 15% by weight of said gum.
- 10. The composition of claim 1 wherein said set retarder is comprised of a copolymer of 2-acrylamido, 2-methyl-propane sulfonic acid and acrylic acid having an average molecular weight below about 5000 and comprising from about 40 to about 60 mole percent of a copolymer of 2-acrylamido, 2-methyl-propane sulfonic acid, said set retarder being present in said composition in an amount in the range of from about 0.1% to about 5% by weight of hydraulic cement in said composition.
- 11. The composition of claim 7 wherein said set retarder is further characterized to include tartaric acid or a salt thereof present in an amount in the range of from about 0.1% to about 5% by weight of hydraulic cement in said composition.
- 12. The composition of claim 1 which is further characterized to include at least one fluid loss additive therein.
- 13. The composition of claim 12 wherein said fluid loss additive is an aqueous solution of the reaction product of polyethyleneimine and one or more sulfonated organic compounds present in said composition in an amount in the range of from about 2.5% to about 10% by weight of hydraulic cement in said composition.
- 14. The composition of claim 1 wherein said set retarder is comprised of a copolymer of 2-acrylamido, 2-methyl-propane sulfonic acid and acrylic acid having an average molecular weight below about 5000 and comprising from about 40 to about 60 mole percent of a copolymer of 2-acrylamido, 2-methyl-propane sulfonic acrylic acid present in an amount in the range of from about 0.5% to about 2% by weight of hydraulic cement in said composition and tartaric acid present in an amount in the range of from about 0.25% to about 2% by weight of hydraulic cement in said composition; and said treated depolymerized galactomannan gum is borate treated guar gum present in an amount in the range of from about 0.2% to about 1.25% by weight of hydraulic cement in said composition.
- 15. The composition of claim 14 which is further characterized to include a fluid loss additive comprised of an aqueous solution of the reaction product of polyethyleneimine and one or more sulfonated organic compounds present in said composition in an amount in the range of from about 2.5% to about 10% by weight of hydraulic cement in said composition.
CROSS-REFERENCE TO RELATED APPLICATION
This is a division of application Ser. No. 07/767,299 filed Sep. 27, 1991 , now at U.S. Pat. No. 5,184,680, issued Feb. 9, 1993.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
3794115 |
Skagersberg |
Feb 1974 |
|
4777360 |
Almond |
Oct 1984 |
|
4997487 |
Vinson et al. |
Mar 1991 |
|
Divisions (1)
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Number |
Date |
Country |
Parent |
767299 |
Sep 1991 |
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