US3521709A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Producing oil from oil shale by heating with hot gases
Assignee: Phillips Petroleum Co
•
Filing: 1967-04-03
•
Granted: 1970-07-28
•
Expires: 1987-04-03
Abstract
No abstract record available.
Inventors
- 👤 Riley B Needham
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:46
CPC Classifications
C; C10; C10G; C10G1/00; C10G1/02
Claims Analysis
Total Claims: 0
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References Cited (Backward Citations)
US3001775A
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US3149670A
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US3223158A
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US3205942A
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US3285335A
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US3273640A
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US3342257A
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US3284281A
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US3316020A
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US3346044A
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US3382922A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1973-07-27 | 1974-01-26 | 1974-07-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1977-07-27 | 1978-01-26 | 1978-07-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1981-07-27 | 1982-01-26 | 1982-07-28 | $7700.00 | Window Closed / Lapsed |