Claims
- 1. An aqueous fluid selected from drilling and packer fluids and containing, as thinner, an effective thinning amount of a water soluble polymer that has a viscosity of below 300 cps (Brookfield Viscometer, Model RVT, Spindle No. 1, speed 20 rpm, 15% by weight active polymer solution at 20.degree. C.) and a polydispersity below 2.0 and that is formed from (a) 10 to 60% by weight 2-acrylamido-2-methyl propane sulphonic acid and (b) 40 to 90% by weight acrylic acid, wherein the acid groups are selected from free acid groups and ammonium and alkali metal salts thereof, and having a molecular weight of 1,000 to 8,000, said fluid 25 to 150 g/l colloidal clay
- 2. A fluid according to claim 1 in which the polymer has a polydispersity below 1.8.
- 3. A fluid according to claim 1 in which the polymer has a molecular weight below 6,000.
- 4. A fluid according to claim 1 in which the polymer has a polydispersity below 1.6.
- 5. A fluid according to claim 1 in which the amount of (a) is 10 to 25% by weight and the amount of (b) is 75 to 90% by weight.
- 6. A fluid according to claim 1 in which the copolymer has a molecular weight of 1,000 to 6,000, and is a copolymer of 10 to 45% by weight of 2-acrylamido-2-methyl-propane sulphonic acid, sodium salt and 55 to 90% by weight sodium acrylate.
- 7. A fluid according to claim 1 containing at least 0.25 g/l dissolved calcium.
- 8. A fluid according to claim 1 in which the polymer is formed from 18 to 22% by weight 2-acrylamido-2-methyl propane sulphonic acid sodium salt and 78 to 82% by weight sodium acrylate and has a molecular weight of 2,000 to 4,500.
- 9. A fluid according to claim 1 in which the amount of said thinner is from 0.15 to 30 g/l.
- 10. A fluid according to claim 1 in which said viscosity is below 50 cps.
- 11. A fluid according to claim 1 further including inorganic particulate selected from the group consisting of drilled rock particles and 100 to 1000 g/l weighting agent and combinations thereof.
- 12. An aqueous fluid selected from drilling and packer fluids and containing 25 to 150 g/l colloidal clay and, as thinner, an effective thinning amount of a water soluble polymer that has a viscosity below 300 cps (Brookfield Viscometer, Model RVT, Spindle No. 1, speed 20 rpm, 15% by weight active polymer solution at 20.degree. C.) and a polydispersity below 2 and a molecular weight from 2000 to 4500 and that is formed from 15 to 25% by weight 2-acrylamido-2-methyl propane sulphonic acid sodium salt and 85 to 75% by weight sodium acrylate.
- 13. A fluid according to claim 12 in which the polymer has a polydispersity below 1.8.
- 14. A fluid according to claim 13 in which the polymer has a polydispersity from 1.35 to 1.6.
- 15. A fluid according to claim 14 in which the amount of 2-acrylamido-2-methyl propane sulphonic acid sodium salt is 20 weight %.
Priority Claims (1)
Number |
Date |
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Kind |
8419805 |
Aug 1984 |
GBX |
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Parent Case Info
This application is a continuation in part of U.S. Ser. No. 641,901 filed 20th Aug. 1984 (now abandoned), U.S. Ser. No. 672,308 filed 16th Nov. 1984 (now U.S. Pat. No. 4,564,387) and U.S. Ser. No. 612,516 filed 21st May 1984 (now U.S. Pat. No. 4,507,422).
US Referenced Citations (16)
Foreign Referenced Citations (6)
Number |
Date |
Country |
0068887 |
May 1983 |
EPX |
0108842 |
May 1984 |
EPX |
1414964 |
Nov 1975 |
GBX |
1505555 |
Mar 1978 |
GBX |
2070108 |
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GBX |
Related Publications (2)
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Date |
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672308 |
Nov 1984 |
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612516 |
May 1984 |
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Continuation in Parts (1)
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Number |
Date |
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Parent |
641901 |
Aug 1984 |
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