Patent US3572771A successfully refreshed from Google Patents.
US3572771A
Expired / Lapsed
US
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Drill-collar construction
Assignee: OILWELL Inc A CORP OF
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Filing: 1968-12-31
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Granted: 1971-03-30
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Expires: 1988-12-31
Abstract
Abstract A drill-collar construction for use in rotary drilling of wells. The individual collars are joined end-to-end with connectors which have greater fatigue resistance than the steel of the drill collars. The preferred metal for the connectors is titanium or a titanium-base alloy.
Inventors
- 👤 Fletcher Redwine
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 02:31
CPC Classifications
E; E21; E21B; E21B17/00; E21B17/16
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
89 words
In a drill string for use in rotary drilling of a well, a series of drill collars and short-length connectors threadedly engaged with the ends of said collars and joining them end-toend, said collars being formed of an alloy steel which has a relatively high modulus of elasticity and low fatigue strength, said connectors being formed of titanium which has a lower modulus of elasticity and a higher fatigue strength, whereby flexing in the series of drill collars takes place in said connectors rather than in the collars themselves.
Claim 2
Dependent Claim
89 words
In a drill string for use in rotary drilling of a well, a series of drill collars and short-length connectors threadedly engaged with the ends of said collars and joining them end-toend, said collars being formed of an alloy steel which has a relatively high modulus of elasticity and low fatigue strength, said connectors being formed of titanium which has a lower modulus of elasticity and a higher fatigue strength, whereby flexing in the series of drill collars takes place in said connectors rather than in the collars themselves.
Claim 3
Dependent Claim
64 words
A series of drill collars as defined in claim 1 in which the collars themselves have a modulus of elasticity of about 29 million to 30 million p.s.i. and a wet fatigue strength in drilling mud of about 13,000 p.s.i., and said connectors have a modulus of elasticity of about 16,200,000 p.s.i. and a wet fatigue strength in drilling mud of about 95,000 p.s.i.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-29 | 1974-09-28 | 1975-03-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-29 | 1978-09-28 | 1979-03-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-29 | 1982-09-28 | 1983-03-30 | $7700.00 | Window Closed / Lapsed |