Wells – Processes – Operating valve – closure – or changeable restrictor in a well
Reexamination Certificate
2000-11-15
2001-12-11
Neuder, William (Department: 3672)
Wells
Processes
Operating valve, closure, or changeable restrictor in a well
C166S321000, C166S332800
Reexamination Certificate
active
06328109
ABSTRACT:
BACKGROUND OF THE INVENTION
Prior to the commencement of production in a wellbore, it is important to test the integrity and the connections of downhole equipment and tubing. Leaks, faulty connections, or faulty equipment can lead to hydrocarbon losses during production and potentially dangerous and life-threatening situations for operators at the surface of a well. To lessen the danger, a pressure test is normally performed in which the tubing (e.g., production tubing) or drillpipe is pressurized from the surface and any leaks or faulty connections are detected by a loss of pressure as measured by a gauge also located at the surface. To successfully accomplish this test, the tubing or drillpipe must be plugged at some point downhole and be sealed from a selected formation.
The types of devices previously used to plug the tubing or pipe downhole include closed formation tester valves and tubing tester valves. Flapper valves have also been utilized for such a purpose, as illustrated in U.S. Pat. No. 4,134,455 issued to Read, U.S. Pat. No. 4,694,903 issued to Ringgenberg, U.S. Pat. No. 5,137,090 issued to Hare et al., and U.S. Pat. No. 5,188,182 issued to Echols et al. The flapper valves disclosed in the above referenced patents are generally designed to seal against pressure adjacent the upper side (e.g., pressure from the uphole side) of the flapper valve.
The ability to seal against both uphole and downhole pressure is important because pressure may accumulate in the wellbore underneath the downhole plug. Therefore, it is desirable that a flapper valve be capable of withstanding not only pressure on its upper side generated by the pressure tests, but also pressure on its underside generated by the production fluids or downhole environment.
Additionally, pressure tests are typically conducted several times in sequence, generally each time additional tubing or drillpipe has been added to a drillstring and inserted downhole. The flapper valve must maintain its sealing engagement to the relevant tubing or drillpipe throughout each of the pressure tests in order to preserve the accuracy of each test. Once the pressure tests are completed and the wellbore is ready for production, it is necessary to remove, at least partially, the downhole valve or plug in order to pass other downhole tools through the drillpipe or tubing, or to allow production fluids to flow up to the surface through the tubing or drillpipe. It is preferable to completely remove the downhole valve or plug from the bore of the tubing or drillpipe so that the downhole tools and production fluids can pass and flow freely and without obstruction.
Attempts have been made to design a downhole plug that provides for a clear bore when the valve is opened. However, most plugs (such as those in the aforementioned patents) include parts (e.g., valve seats or internal tubing) that remain in the bore after the flapper has been removed or opened. Parts that remain in the bore may obstruct the passage of tools and the flow of fluids through the bore. It is therefore desirable to provide a downhole valve which enables the complete removal of the flapper valve from the bore of the relevant body at the appropriate time and which leaves such bore free of obstructions after use.
SUMMARY OF THE INVENTION
One aspect of the invention is a downhole valve comprising a body and a flow tube assembly positioned within the body. The flow tube assembly comprises an upper tube member and a lower tube member. A flapper valve is operatively attached to the flow tube assembly and is adapted to move from a closed position to an open position. When the flapper valve is in the closed position, the flapper valve is sealingly positioned between the upper and lower tube members. When the flapper valve is moved to the open position, the flapper valve is enclosed in a recess in the body. The movement of the flapper valve is in response to an upward movement of the upper and lower tube members so that after the flapper valve is enclosed in the recess, the upper and lower tube members move into a cooperative engagement with each other to form a substantially unobstructed internal bore.
Another aspect of the invention is a method of retractably sealing a bore of a body. The method comprises pivotally attaching a flapper valve to the body. A top surface of the flapper valve sealingly engages an upper tube member when the flapper valve is in a closed position. A bottom surface of the flapper valve sealingly engages a lower tube member when the flapper valve is in the closed position. The flapper valve is moved from the closed position to an open position in response to a plurality of pressure cycles by slidably moving the upper tube member and the lower tube member upward until the flapper valve is enclosed in a recess in the body and the upper tube member cooperatively engages the lower tube member.
Other aspects and advantages of the invention will be apparent from the following description and the appended claims.
REFERENCES:
patent: 2849207 (1958-08-01), Conrad
patent: 2912216 (1959-11-01), Conrad
patent: 2931384 (1960-04-01), Clark
patent: 2952438 (1960-09-01), Conrad et al.
patent: 4134455 (1979-01-01), Read
patent: 4154303 (1979-05-01), Fournier
patent: 4185690 (1980-01-01), Kinney
patent: 4393930 (1983-07-01), Ross et al.
patent: 4457376 (1984-07-01), Carmody et al.
patent: 4457379 (1984-07-01), McStravick
patent: 4541484 (1985-09-01), Salerni et al.
patent: 4566478 (1986-01-01), Deaton
patent: 4617960 (1986-10-01), More
patent: 4624317 (1986-11-01), Barrington
patent: 4632187 (1986-12-01), Deaton
patent: 4691775 (1987-09-01), Lustig et al.
patent: 4694903 (1987-09-01), Ringgenberg
patent: 4716968 (1988-01-01), Pringle
patent: 4813481 (1989-03-01), Sproul et al.
patent: 4846281 (1989-07-01), Clary et al.
patent: 5137090 (1992-08-01), Hare et al.
patent: 5188182 (1993-02-01), Echols, III et al.
patent: 5188183 (1993-02-01), Hopmann et al.
patent: 5310005 (1994-05-01), Dollison
patent: 5417285 (1995-05-01), Van Buskirk et al.
patent: 5479986 (1996-01-01), Gano et al.
patent: 5765641 (1998-06-01), Shy et al.
patent: 5803173 (1998-09-01), Fraser, III et al.
patent: 5947204 (1999-09-01), Barton
patent: 5990051 (1999-11-01), Ischy et al.
patent: 2073288 (1981-10-01), None
patent: 2110741 (1983-06-01), None
patent: 2245913 (1992-01-01), None
patent: WO 97/28349 (1997-08-01), None
Milligan, Jr. Clay W.
Pringle Ronald E.
Read Dennis M.
Neuder William
Schlumberger Technology Corp.
Trop Pruner & Hu P.C.
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