Patent US2219312A successfully refreshed from Google Patents.
US2219312A
Expired / Lapsed
US
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Method for controlling the properties of drilling fluids
Assignee: NL Industries Inc
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Filing: 1938-10-24
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Granted: 1940-10-29
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Expires: 1958-10-24
Abstract
No abstract record available.
Inventors
- 👤 John T Hayward
- 👤 Earl E Huebotter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:14
CPC Classifications
E; E21; E21B; E21B21/00; E21B21/06; E21B21/063; B; B01; B01D; B01D29/00; B01D29/11; B01D57/00; B01D57/02
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) | 1943-10-29 | 1944-04-29 | 1944-10-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1947-10-29 | 1948-04-29 | 1948-10-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1951-10-29 | 1952-04-29 | 1952-10-29 | $7700.00 | Window Closed / Lapsed |