US2220788A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for investigating subterranean strata by means of electromagnetic measurements
Assignee: Schlumberger Well Surveying Corp
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Filing: 1935-06-24
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Granted: 1940-11-05
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Expires: 1955-06-24
Abstract
No abstract record available.
Inventors
- 👤 Ralph W Lohman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 16:35
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/18; G01V3/26; G01V3/28
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) | 1943-11-05 | 1944-05-06 | 1944-11-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1947-11-05 | 1948-05-06 | 1948-11-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1951-11-05 | 1952-05-06 | 1952-11-05 | $7700.00 | Window Closed / Lapsed |