US3566980A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Underbalanced drilling sub
Assignee: Drilling Well Control Inc
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Filing: 1969-12-03
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Granted: 1971-03-02
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Expires: 1989-12-03
Abstract
Abstract A pressure reducing apparatus insertable in a drill string to reduce the fluid pressure immediately surrounding the drill bit and a method for accomplishing pressure reduction. It includes a body with an axial bore, fluid passages in the body communicating with the annulus of the well, and means to divert normal axial drilling fluid flow upwardly through the opened passages. When the fluid is diverted through the passages, a venturi effect is created, thereby reducing the pressure on the drill bit in the area below the passages. The method includes diverting the axial flow of the drilling fluid by restriction of a portion of the inner bore of the well string while the fluid is pumped at a substantially constant rate.
Inventors
- 👤 Elva J Scroggins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 07:31
CPC Classifications
E; E21; E21B; E21B21/00; E21B21/08; E21B10/00; E21B10/60
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
54 words
The invention as claimed in claim 1 wherein said flow restricting means and said diversion means include an integrated tube and plug assembly, whereby predetermined downward sliding movement of said assembly from a suspended attitude within said body simultaneously restricts said axial fluid flow and opens said plurality of fluid passages to the annulus.
Claim 2
Dependent Claim
33 words
The invention as claimed in claim 2 including means mounted in said body for suspending said tube and plug assembly from an upper portion of said body during normal axial fluid flow conditions.
Claim 3
Dependent Claim
40 words
The invention as claimed in claim 3 wherein the tubular portion of said tube and plug assembly forms a plurality of fluid bypass passages, whereby axial fluid flow is maintained generally through said bore during normal axial flow drilling operations.
Claim 4
Dependent Claim
40 words
The invention as claimed in claim 1 wherein said plurality of generally upwardly slanted passages formed by said body are each fitted with an orifice insert which directs said diverted fluid flow in a generally upward direction into said annulus.
Claim 5
Dependent Claim
95 words
The invention as claimed in claim 1 wherein said moving means includes a generally cylindrical tool arranged for passage through the bore of a drill string, said tool having along a first portion thereof means arranged for engaging and disengaging said restricting means and said diverting means and forming along a second portion thereof a plurality of fluid passages arranged to allow fluid flow about and through said tool during the moving operation and normal axial flow operations and having along a third portion thereof a fishing neck arranged for coupling with a wireline tool.
Claim 6
Dependent Claim
50 words
The invention as claimed in claim 6 wherein said engaging and disengaging portion of said tool includes a plurality of resilient fingers mounted on an axially slidable and downwardly presprung base enclosed within an overshot shell, said shell having an open end into which said diverting and restricting means engages.
Claim 7
Dependent Claim
128 words
In a method for varying fluid pressure in the area generally surrounding an operating drill bit suspended on a drill string in a well bore, the combination of steps comprising: flowing drilling fluid downwardly through said drill string and drill bit and upwardly through the annulus of the well at a substantially constant rate while rotating said drill string and bit; reducing the cross-sectional area of a portion of the internal bore of said drill string at predetermined times; simultaneously diverting a portion of said drilling fluid generally upwardly and outwardly through bypass points spaced above said drill bit while maintaining reduced fluid flow through said a really reduced portion of said bore; and whereby the fluid pressure is reduced in said well bore below said bypass points.
Claim 8
Dependent Claim
30 words
The invention as clAimed in claim 8 including subsequently terminating said flow of drilling fluid through said bypass points and resuming normal fluid flow of drilling fluid to said bit.
References Cited (Backward Citations)
US1619328A
Cited
US2128352A
Cited
US2765146A
Cited
US2805043A
Cited
US2828107A
Cited
US3116800A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-01 | 1974-08-31 | 1975-03-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-01 | 1978-08-31 | 1979-03-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-01 | 1982-08-31 | 1983-03-02 | $7700.00 | Window Closed / Lapsed |