US4602067A
Expired / Lapsed
US
⏱️ 0.0 years remaining
High temperature drilling fluids
Assignee: Pfizer Inc
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Filing: 1985-03-28
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Granted: 1986-07-22
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Expires: 2005-03-28
Abstract
Abstract An aqueous drilling fluid suitable for high-temperature use comprising a water base, clay suspended in said base and from about 0.01-25 pounds per barrel total composition of a hydrolyzed terpolymer of maleic anhydride, styrene and a third monomer selected from acrylamide, methacrylamide, acrylic acid or methacrylic acid, the molar ratio of maleic anhydride to styrene to said third monomer being from about 30:10:60 to 50:40:10, and the alkali metal, ammonium and lower aliphatic amine salts thereof, the weight-average molecular weight of said hydrolyzed terpolymer being from about 500-10,000. An improved drilling process wherein such fluids remain flowable at elevated temperatures is also disclosed.
Inventors
- 👤 Randel E. Stong
- 👤 Stanley W. Walinsky
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 13:51
CPC Classifications
C; C09; C09K; C09K8/00; C09K8/02; C09K8/04; C09K8/14; C09K8/18; C09K8/22; C09K8/24
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
86 words
A partially amidated terpolymer comprising: (a) maleic anhydride; (b) styrene; and (c) acrylic or methacrylic acid; wherein the molar ratio of said components (a), (b) and (c) is from about 30:10:60 to about 50:40:10; and wherein from about 1-42 percent of carboxylic functionality has been converted to amide functionality by treatment with ammonia, ammonium hydroxide or primary or secondary lower alkyl amines having from about 1-5 carbon atoms in each alkyl group; the weight average molecular weight of said partially amidated terpolymer being from about 500-10,000.
Claim 2
Dependent Claim
86 words
A partially amidated terpolymer comprising: (a) maleic anhydride; (b) styrene; and (c) acrylic or methacrylic acid; wherein the molar ratio of said components (a), (b) and (c) is from about 30:10:60 to about 50:40:10; and wherein from about 1-42 percent of carboxylic functionality has been converted to amide functionality by treatment with ammonia, ammonium hydroxide or primary or secondary lower alkyl amines having from about 1-5 carbon atoms in each alkyl group; the weight average molecular weight of said partially amidated terpolymer being from about 500-10,000.
Claim 3
Dependent Claim
20 words
The terpolymer of claim 1 wherein said component (C) is acrylic acid and wherein said treatment is with ammonium hydroxide.
Claim 4
Dependent Claim
84 words
A partially amidated copolymer comprising: (a) maleic anhydride and (b) acrylic or methacrylic acid; wherein the molar ratio of said component (a) to said component (b) is from about 25:75 to 75:25; and wherein from about 0.5-42 percent of carboxylic functionality has been converted to amide functionality by treatment with ammonia, ammonium hydroxide or primary or secondary lower alkyl amines having from about 1-5 carbon atoms in each alkyl group; the weight average molecular weight of said partially amidated copolymer being from about 500-10,000.
Claim 5
Dependent Claim
84 words
A partially amidated copolymer comprising: (a) maleic anhydride and (b) acrylic or methacrylic acid; wherein the molar ratio of said component (a) to said component (b) is from about 25:75 to 75:25; and wherein from about 0.5-42 percent of carboxylic functionality has been converted to amide functionality by treatment with ammonia, ammonium hydroxide or primary or secondary lower alkyl amines having from about 1-5 carbon atoms in each alkyl group; the weight average molecular weight of said partially amidated copolymer being from about 500-10,000.
Claim 6
Dependent Claim
20 words
The copolymer of claim 3 wherein said component (b) is acrylic acid and wherein said treatment is with ammonium hydroxide.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-07-21 | 1990-01-20 | 1990-07-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-07-21 | 1994-01-20 | 1994-07-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-07-21 | 1998-01-20 | 1998-07-22 | $7700.00 | Window Closed / Lapsed |