US2947520A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Well casing back-off tool
Assignee: Shell USA Inc
•
Filing: 1953-12-28
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Granted: 1960-08-02
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Expires: 1973-12-28
Abstract
No abstract record available.
Inventors
- 👤 Ronald A Tappmeyer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:20
CPC Classifications
E; E21; E21B; E21B17/00; E21B17/02; E21B17/021
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1963-08-02 | 1964-02-01 | 1964-08-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1967-08-02 | 1968-02-01 | 1968-08-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1971-08-02 | 1972-02-01 | 1972-08-02 | $7700.00 | Window Closed / Lapsed |