Patent US1660187A successfully refreshed from Google Patents.
US1660187A
Expired / Lapsed
US
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Method of winning petroleum
Assignee: FIRM TERRA AG
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Filing: 1920-10-08
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Granted: 1928-02-21
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Expires: 1940-10-08
Abstract
No abstract record available.
Inventors
- 👤 Ehrat Adolf
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:57
CPC Classifications
E; E21; E21C; E21C41/00; E21C41/16; E21C41/24
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) | 1931-02-20 | 1931-08-22 | 1932-02-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1935-02-20 | 1935-08-22 | 1936-02-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1939-02-20 | 1939-08-22 | 1940-02-21 | $7700.00 | Window Closed / Lapsed |