Patent US2336171A successfully refreshed from Google Patents.
US2336171A
Expired / Lapsed
US
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Oil well drilling fluid
Assignee: Shell Development Co
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Filing: 1940-06-22
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Granted: 1943-12-07
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Expires: 1960-06-22
Abstract
No abstract record available.
Inventors
- 👤 John W Freeland
- 👤 Harold T Byck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:22
CPC Classifications
C; C09; C09K; C09K8/00; C09K8/02; C09K8/04; C09K8/14; C09K8/18; C09K8/20; C09K8/206
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1946-12-06 | 1947-06-07 | 1947-12-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1950-12-06 | 1951-06-07 | 1951-12-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1954-12-06 | 1955-06-07 | 1955-12-07 | $7700.00 | Window Closed / Lapsed |