US3169587A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of removing formating fluids from a well bore in drilling operations
Assignee: Cyprus Amax Minerals Co
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Filing: 1961-09-26
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Granted: 1965-02-16
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Expires: 1981-09-26
Abstract
No abstract record available.
Inventors
- 👤 William C Hubbard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 03:50
CPC Classifications
E; E21; E21B; E21B21/00; E21B21/10; E21B21/103
Claims Analysis
Total Claims: 1
Claim 1
Independent Claim
143 words
IN COMBINATION WITH WELL DRILLING APPARATUS, A HOLLOW DRILL STRING FOR DRIVING A BIT IN WHICH THE HOLLOW OF THE DRILL STRING FORMS A FIRST CONDUIT FOR PRESSURE FLUID DURING DRILLING AND THE ANNULUS BETWEEN THE WALL BORE AND THE OUTER SURFACE OF THE DRILL STRING FORMS A SECOND CONDUIT FOR REMOVAL OF FORMATION FLUID, SAID DRILL STRING INCLUDING HOLLOW SUBS JOINING PIPE SECTIONS TOGETHER, EACH SUB HAVING A DIFFERENTIAL PRESSURE VALVE SUPPORTED IN ITS INTERIOR FOR BLEEDING PRESSURE FROM SAID FIRST TO SAID SECOND OND CIRCUIT, EACH OF SAID VALVES HAVING A DIFFERENT OPENING PRESSURE AND HAVING A CLOSING PRESSURE LESS THAN ITS OPENING PRESSURE, SAID SUBS BEING ARRANGED FROM THE TOP OF THE DRILL STRING DOWN SO THAT EACH SUCCEEDING VALVE FROM THE TOP VALVE DOWN HAS AN OPENING PRESSURE LESS THAN THE CLOSING PRESSURE OF THE VALVE IMMEDIATELY ABOVE IT.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1968-02-16 | 1968-08-17 | 1969-02-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1972-02-16 | 1972-08-17 | 1973-02-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1976-02-16 | 1976-08-17 | 1977-02-16 | $7700.00 | Window Closed / Lapsed |