Patent US3605920A successfully refreshed from Google Patents.
US3605920A
Expired / Lapsed
US
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Core drilling apparatus with means to indicate amount of core in barrel
Assignee: Texaco Inc
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Filing: 1969-12-30
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Granted: 1971-09-20
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Expires: 1989-12-30
Abstract
Abstract THE CORE BARREL OF A CORE DRILL HAS LONGITUDINALLY SPACED PORTS IN ITS SIDEWALLS AND A PLUG SLIDABLE IN THE BARREL. AS THE CORE ENTERS THE BARREL IT RAISES THE PLUG. BLOCKING THE PORTS IN TURN AND THUS PRODUCING PRESSURE CHANGES OR ANOMALIES IN THE DRILLING FLUID INDICATIVE OF THE AMOUNT OF CORE IN THE BARREL.
Inventors
- 👤 Charles D Woodward
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:00
CPC Classifications
E; E21; E21B; E21B25/00
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) | 1974-09-19 | 1975-03-21 | 1975-09-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-19 | 1979-03-21 | 1979-09-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-19 | 1983-03-21 | 1983-09-20 | $7700.00 | Window Closed / Lapsed |