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Patent US3456720A successfully refreshed from Google Patents.
US3456720A
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Apparatus and method for drilling wells
Assignee: JOHN S BREWER
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Filing: 1967-01-11
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Granted: 1969-07-22
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Expires: 1987-01-11
Abstract
No abstract record available.
Inventors
- 👤 John S Brewer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 21:53
CPC Classifications
E; E21; E21B; E21B15/00; E21B15/02; E02; E02B; E02B17/00; E02B17/02; E02B17/027; E21B43/00; E21B43/01; E02B2017/0056; E02B2017/0069; E02B2017/0073; E02B2017/0086
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US2171672A
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US2622404A
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US2669846A
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US2691272A
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US2756021A
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US2783970A
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US3202218A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1972-07-21 | 1973-01-20 | 1973-07-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1976-07-21 | 1977-01-20 | 1977-07-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1980-07-21 | 1981-01-20 | 1981-07-22 | $7700.00 | Window Closed / Lapsed |