Wells – Above ground apparatus – Inner member anchor or seal with lateral port
Reexamination Certificate
1999-02-19
2001-01-23
Shackelford, H. (Department: 3671)
Wells
Above ground apparatus
Inner member anchor or seal with lateral port
C166S196000, C277S328000, C277S337000, C277S339000
Reexamination Certificate
active
06176310
ABSTRACT:
REFERENCE TO PENDING APPLICATIONS
This application is not related to any pending United States or international patent application.
REFERENCE TO MICROFICHE APPENDIX
This application is not referenced in any Microfiche Appendix.
BACKGROUND OF THE INVENTION
The customary procedure for drilling an oil and gas well is to anchor a relatively large diameter surface pipe in the earth down through which the bore hole for the well is drilled. A well head is secured to the upper end of the surface pipe. Suspended within the surface pipe and extending down into the bore hole is typically a string of casing pipe and within the casing pipe a string of tubing, the tubing pipe serving as the conduit by which produce liquids and/or gases are conveyed from the producing formation to the earth's surface. A hanger is employed by which the casing string and/or tubing string is suspended from the well head. A sealing system is required to seal the annular space between the interior of the well head and the exterior of the hanger supported within the well head. This invention provides an improved sealing system for this purpose.
Nearly all casing and tubing hanger seals in use today utilize an elastomeric element and elastomeric seals have known limitations. They tend to loose their effectiveness when exposed to heat or to corrosive substances such as hydrocarbons or hydrogen sulphide or to great pressures over a long period of time. The natural aging process of elastomers causes them to harden and become brittle over time and once hardened and brittle they lose their sealing effectiveness and may thereafter permit leakage to occur. In some instances the long exposure of elastomeric seals to high pressures can cause them to flow and creep permitting leakage of gases or liquids to the environment.
In recent years, effort has been made to replace elastomeric tubing or casing hanger seals with more reliable and longer lasting metal to metal seals. The invention described herein is for an improved metal to metal seal to close the annulus between concentric cylindrical surfaces such as the concentric surfaces between the interior cylindrical surface of a well head and the exterior cylindrical surface of a tubing or casing hanger.
For background information of the art to which the present invention relates reference can be made to the following previously issued United States Patents.
U.S. Pat. No.
INVENTOR
TITLE
4,131,287
Gunderson et al
Annular Seal
4,556,224
Le
Crossover Seal Assembly
4,588,029
Blizzard
Expandable Metal Seal for
a Well Tool
4,646,845
Boeker
Metal Seal for Wellhead
Apparatus
4,665,979
Boehm, Jr.
Metal Casing Hanger Seal
with Expansion Slots
4,742,874
Gullion
Subsea Wellhead Seal
Assembly
4,751,965
Cassity
Wellhead Seal Assembly
4,823,871
McEver et al
Hanger and Seal Assembly
5,044,672
Skeels et al
Metal-to-metal Sealing
Pipe Swivel Joint
5,110,144
Burton et al
Casing Hanger Seal
Assembly
5,325,925
Smith et al
Sealing Method and
Apparatus for Wellheads
BRIEF SUMMARY OF THE INVENTION
The invention herein is an assembly for sealing the annulus between concentric cylindrical surfaces. A typical application for the invention and one to which it is particularly adapted is that of sealing the annular space between a well head and a casing hanger or tubing hanger. The hanger external cylindrical surface is defined by spaced apart circumferential portions of increased external diameters in the downward direction providing (a) an upper sealing surface, (b) an intermediate upper sealing surface, (c) an intermediate lower sealing surface and (d) a lower sealing surface. The well head has a test port extending from an exterior surface to its internal cylindrical surface.
The sealing assembly includes tubular upper and lower seal members that are received on hanger cylindrical surface. The upper seal member has an outwardly deflectable circumferential sealing lip, a downwardly extending circumferential inner seal and an upperwardly extending circumferential inner seal. The tubular lower seal member is also received on the external cylindrical surface of the hanger below the upper seal member. The tubular lower seal member has a radially outwardly deflectable circumferential sealing lip, a downwardly extending circumferential inner seal and an upwardly extending circumferential inner seal. Thus the upper and lower seal member together have a total of two outwardly deflectable circumferential sealing lips and four circumferential inner seals.
A tubular actuator is received on the hanger cylindrical surface between the upper and lower seal members.
Completing the sealing assembly is an energizer that is threaded on to the upper end portion of the hanger. When the energizer is downwardly displaced the upper seal member is moved downwardly toward the lower seal member to forcibly downwardly displace the seal members to cause the actuator to radially outwardly deflect the upper and lower circumferential sealing lips against the well head cylindrical surface. The downward displacement of the seal members by the energizer also causes the four inner seals to sealably engage the four hanger sealing surface to thereby seal the annular space while isolating the test port between the intermediate upper and lower sealing surfaces.
Thus the sealing assembly when employed in the specific embodiment as used to seal the annular space between the internal cylindrical surface of a well head and the external cylindrical surface of a hanger function not only to seal this surface against the passage of fluids or gases through the annular area but also provides an intermediate closed annular space between the upper and lower seals that has communication with the test port. By opening the test port a workman can verify that the seal assembly is functioning for its intended purpose of preventing the passage of fluids or gases into or out of the annular area.
The invention will be better understood by reference to the detailed description of the preferred embodiments, taken in conjunction which with the attached drawings.
REFERENCES:
patent: 2205739 (1940-06-01), Wilson
patent: 2714932 (1955-08-01), Thompson
patent: 4131287 (1978-12-01), Gunderson et al.
patent: 4556224 (1985-12-01), Le
patent: 4588029 (1986-05-01), Blizzard
patent: 4628997 (1986-12-01), Schraub
patent: 4646845 (1987-03-01), Bocker
patent: 4665979 (1987-05-01), Boehm, Jr.
patent: 4742874 (1988-05-01), Guillon
patent: 4751965 (1988-06-01), Cassity
patent: 4791992 (1988-12-01), Greenlee et al.
patent: 4823871 (1989-04-01), McEver et al.
patent: 5044672 (1991-09-01), Skeels et al.
patent: 5110144 (1992-05-01), Burton et al.
patent: 5325925 (1994-07-01), Smith et al.
Lane Floyd J.
Smith Jerry D.
ERC Industries, Inc.
Head Johnson & Kachigian
Shackelford H.
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