U.S. patent application number 10/143304 was filed with the patent office on 2003-11-13 for metal end cap seal with o-ring.
This patent application is currently assigned to Cooper Cameron Corporation. Invention is credited to Keene, Kendall E..
Application Number | 20030209857 10/143304 |
Document ID | / |
Family ID | 29400095 |
Filed Date | 2003-11-13 |
United States Patent
Application |
20030209857 |
Kind Code |
A1 |
Keene, Kendall E. |
November 13, 2003 |
Metal end cap seal with o-ring
Abstract
The present invention relates to a metal end cap seal for a well
sealing assembly for sealing the annulus between two tubular
members that has improved sealing abilities at an increased range
of temperatures. The metal end cap seal generally comprises a
resilient ring with a metal end caps on either end. The inner
diameter of the resilient ring has one or more grooves that enable
the installation of a one or more o-rings. The o-rings are sized so
as to provide an increased stored energy within the resilient ring
so that the sealing engagement is increased.
Inventors: |
Keene, Kendall E.; (Houston,
TX) |
Correspondence
Address: |
CONLEY ROSE, P.C.
P. O. BOX 3267
HOUSTON
TX
77253-3267
US
|
Assignee: |
Cooper Cameron Corporation
1333 west Loop South
Houston
TX
77027-9109
|
Family ID: |
29400095 |
Appl. No.: |
10/143304 |
Filed: |
May 10, 2002 |
Current U.S.
Class: |
277/336 |
Current CPC
Class: |
F16J 15/128 20130101;
E21B 33/03 20130101 |
Class at
Publication: |
277/336 |
International
Class: |
E21B 033/10 |
Claims
What is claimed is:
1. seal assembly comprising: a resilient ring having a generally
flat first side surface, a convex second side surface, an upper
surface, and a lower surface; one or more circumferential grooves
on the first side surface of ring; one or more o-rings disposed
within said grooves; a first annular end cap bonded to the upper
surface of said resilient ring and having a first leg along a
portion of the first side surface and second leg along a portion of
the second side surface; and a second annular end cap bonded to the
lower surface of said resilient ring and having a first leg along a
portion of the first side surface and second leg along a portion of
the second side surface.
2. The assembly of claim 1 where the first side surface is the
outer surface of said resilient ring.
3. The assembly of claim 2 wherein having two grooves with one
o-ring disposed in each groove.
4. The assembly of claim 2 wherein said one or more grooves are
dovetail shaped.
5. The assembly of claim 1 where the first side surface is the
inner surface of said resilient ring.
6. The assembly of claim 5 wherein having two grooves with one
o-ring disposed in each groove.
7. The assembly of claim 5 wherein said one or more grooves are
dovetail shaped
8. A method of increasing the available energy stored within a
metal end cap seal having a resilient ring and metal end caps, when
the metal end cap seal is compressed between and inner surface and
an outer surface, by: forming the resilient ring with one or more
circumferential grooves on a first side surface and a convex second
side surface; disposing one or more o-rings within the grooves.
9. The assembly of claim 8 wherein having two grooves with one
o-ring disposed in each groove.
10. The assembly of claim 8 wherein said one or more grooves are
dovetail shaped
11. A seal assembly for sealing the annulus between an inner
tubular and an outer tubular comprising: a resilient ring with
upper and lower flat surfaces, a convex interior surface, and an
outer surface; wherein the interior surface has a circumferential
groove; annular end caps having flat portions bonded to the upper
and lower flat surfaces of said resilient ring and having inner
legs along a portion of the convex surface and outer legs along a
portion of the outer surface; and a sealing member disposed within
the circumferential groove on said resilient ring.
12. The assembly of claim 11 wherein said sealing member is an
o-ring.
13. The assembly of claim 12 wherein said sealing member is
constructed from nitrile having a durometer of 70 or less.
14. The assembly of claim 11 wherein the circumferential groove is
a dovetail groove.
15. The assembly of claim 11 wherein said sealing member has
between a 12% and 15% larger circumference than the circumferential
groove.
16. The assembly of claim 11 wherein said sealing member has at
least 0.015" of radial interference with the inner tubular when the
annulus is sealed.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not applicable.
BACKGROUND OF THE INVENTION
[0003] The present invention relates generally to seals, and more
particularly to well sealing assemblies that seal off an annulus
between two tubular members, especially in wellhead tubing hanger
applications. Still more particularly, the present invention
relates to metal end cap seal assemblies generally comprising a
resilient seal ring with metallic caps affixed to either end of the
seal ring.
[0004] A hydrocarbon well is normally produced through a tubing
string rather than through the casing that lines the wellbore. A
well will often have several strings of tubing through which
production operations can be supported. Because each string of
tubing is often used independently of adjacent strings, the annulus
between adjacent, concentric strings of tubing must be reliably
sealed. These seals must be able to withstand high pressures,
corrosive environments, and a wide range of temperatures. It is
also desirable to have a sealing mechanism that will maintain a
seal without a continuous compressive load, which allows for
simplification of the sealing mechanism as well as the setting and
retrieving procedures.
[0005] One such sealing mechanism is disclosed in U.S. Pat. No.
4,496,162, issued to McEver et al., and incorporated herein by
reference for all purposes. A simplified sealing mechanism, as is
well known in the is shown in FIG. 1. Sealing assembly 10 is
disposed within a housing 12 and is shown in an unset position.
Housing 12 has a tapered surface 28 and a sealing surface 29.
Sealing assembly 10 generally includes tubular body 18 having an
outer surface 26, back-up ring 32, setting sleeve 38, and metal end
cap seal 36. Back-up ring 32 releasably connects to surface 26 by
shear pin 34 and is positioned below seal 36. Setting sleeve 38 is
disposed above seal 36. Metal end cap seal 36 generally comprises a
resilient ring 58 with metallic caps 50, 52 disposed on the top and
bottom of ring 58.
[0006] Now referring to FIG. 2, the sealing assembly 10 is shown in
a set position. Setting sleeve 38 has been moved downward, shearing
pin 34 and moving metal end cap seal 36 into a position between
housing sealing surface 29 and surface 26. In the set position,
resilient ring 58 is compressed between body 18 and housing 12
creating a force on legs 56 of end caps 50, 52, that pushes legs 56
outward toward their related sealing surfaces and creates
metal-to-metal seals between end caps 50 and 52 and the sealing
surfaces of housing 12 and body 18. By having an energized
elastomeric seal effectively protected by metal-to-metal seals,
this sealing arrangement avoids extrusion of the resilient ring and
protects the resilient ring from exposure to wellbore fluids.
[0007] Sealing assemblies utilizing metal end cap seals, such as
that described above, have found widespread use in tubing hanger
applications in a variety of operating conditions by providing seal
assemblies that can be easily energized, avoid seal extrusion, and
can be easily retrieved. Wells today are being drilled in
increasingly harsh environments and the conditions in which these
sealing assemblies have to perform is constantly evolving. One area
in which the performance of metal end cap seal rings has been
problematic is in low temperature applications where energization
of the resilient material becomes difficult due to reduced
temperatures or other environmental effects.
[0008] The preferred embodiments are directed to improved methods
and apparatus for metal end cap seal rings that seek to overcome
these and other limitations of the prior art. In particular the
preferred embodiments are directed to providing an improved metal
end cap seal design that is more easily energized at low
temperatures.
SUMMARY OF THE PREFERRED EMBODIMENTS
[0009] Accordingly, there is provided herein a metal end cap seal
assembly for sealing the annulus between two concentric tubular
members that provides improved sealing performance at a wide range
of temperatures. The metal end cap seal generally comprises a
resilient ring with a metal end caps on either end. The inner
diameter of the resilient ring has one or more grooves that enable
the installation of a one or more o-rings sized so as to enhance
the sealing engagement between the inner tubular section and the
inside diameter of the sealing assembly. The o-rings provide a
stored energy that enables the sealing assembly to more effectively
function at low temperatures.
[0010] The o-rings provide additional interference between the seal
and the inner tubular thereby creating regions of high compression
in the body of the seal. The additional compression causes
localized stress concentrations, while maintaining a desirable
overall stress level through the resilient ring. This stress
distribution enhances the performance of the sealing assembly,
especially in low temperature applications.
[0011] Thus, the preferred embodiments comprise a combination of
features and advantages that enable it to substantially advance
metal end cap seal art by providing apparatus for increasing the
range of temperature performance. These and various other
characteristics and advantages of the preferred embodiments will be
readily apparent to those skilled in the art upon reading the
following detailed description and by referring to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] For a more detailed understanding of the preferred
embodiments, reference is made to the accompanying Figures,
wherein:
[0013] FIG. 1 is a partial sectional view of a sealing assembly in
the unset position;
[0014] FIG. 2 is a partial sectional view of a sealing assembly in
the set position;
[0015] FIG. 3 is a partial sectional view of one embodiment of a
metal end cap seal;
[0016] FIG. 4 is an enlarged partial sectional view of the metal
end cap seal of FIG. 3, shown in the set position; and
[0017] FIG. 5 is a partial sectional view of an alternative
embodiment of a metal end cap seal.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] In the description that follows, like parts are marked
throughout the specification and drawings with the same reference
numerals, respectively. The drawing figures are not necessarily to
scale. Certain features of the invention may be shown exaggerated
in scale or in somewhat schematic form and some details of certain
elements may be omitted in the interest of clarity and
conciseness.
[0019] The preferred embodiments relate to methods and apparatus
for providing an annular seal between concentric tubular members
and are susceptible to embodiments of different forms. There are
shown in the drawings, and herein will be described in detail,
specific embodiments of the present invention with the
understanding that the present disclosure is to be considered an
exemplification of the principles of the invention, and is not
intended to limit the invention to that illustrated and described
herein.
[0020] In particular, various embodiments of the present invention
are described as being used in oilfield applications, in particular
as a tubing hangar seals, but the use of the embodiments is not
limited to either tubing hangars or oilfield applications and may
used in any applicable sealing arrangement. Additionally, although
the preferred embodiments are described with certain features
appearing on either the inside or outside diameter of the seal, it
is understood that these features can be used on either diameter in
any combination as may be appropriate for a given application. It
is to be fully recognized that the different teachings of the
embodiments discussed below may be employed separately or in any
suitable combination to produce desired results.
[0021] Referring now to FIG. 3, a partial cross-section of one
embodiment of a metal end cap seal assembly 60 is shown in an
as-constructed configuration. Metal end cap seal assembly 60
includes a resilient ring 62 having metal end caps 64 and 66
preferably bonded to its upper and lower ends. End caps 64 and 66
have a central portion 74 with inner legs 76b and outer legs 76a
extending in a direction toward the mid point of resilient ring 62.
Outer, central portion 78 of resilient ring 62 is convex shaped,
while inner, central portion 77 of resilient ring 62 is generally
flat and has one or more grooves 68 located thereon. It is
preferred that resilient ring 62 be made of an elastomeric
material, such as a nitrile rubber, and metal end caps be
constructed from a type 316 stainless steel.
[0022] Groove 68, on inner surface 77, is sized to accept an o-ring
70. Groove 68 may be constructed to reduce the possibility of the
o-ring coming out of the groove during installation. This
preferable groove 68 is a dovetail groove that has a
cross-sectional shape roughly approximating a triangle that has one
corner removed to form an opening wherein the width of the opening
is smaller than the diameter of the o-ring. O-ring 70 is preferably
sized so as to be slightly larger than groove 68 in an unloaded
condition.
[0023] Metal end cap assembly 60 is shown in a set position in FIG.
4. Metal end cap seal assembly 60 is shown in relationship with
setting sleeve 38 and back-up ring 32 forming a seal between the
housing 12 and surface 26 of body 18. Resilient ring 62 is
energized by being compressed between housing 12 and body 18. Metal
end caps 64 and 66 are expanded and pushed against housing 12 and
body 18 by energized resilient ring 62. Metal-to-metal seals are
created between the legs 76a, 76b and the sealing surfaces of
housing 12 and body 18. O-rings 70 are compressed against surface
26 to form localized stress concentrations along the inner edge of
resilient ring 62.
[0024] The o-ring 70 is selected to have an interference fit on
surface 26, therefore slightly stretching the o-ring from its
relaxed diameter and storing energy within the o-ring. The stored
energy from the o-ring 70 is transferred to the resilient ring 62
by close engagement between the o-ring and the groove 68. The
energy transferred into the resilient ring 62 increases the energy
stored in the resilient ring and therefore increases the
effectiveness of the seal assembly 60 at all temperatures.
[0025] The preferred o-ring 70 is sized so as to provide at least
0.015" of interference with surface 26 when fully set.
Consequently, the preferred o-ring 70 is designed for 12 to 15%
circumferential compression in the installed position (not shown)
by sizing the o-ring so that its circumferential length is 12-15%
longer than the unset length of the groove 68. Designing o-ring 70
to have circumferential compression in the installed position
allows the o-ring to expand without breaking. O-ring 70 is
preferably constructed from an elastomer or other resilient seal
material that provides low temperature flexibility, such as a
70-durometer nitrile.
[0026] The number and size of the o-rings may vary with the size of
the seal. FIG. 4 shows another embodiment of a metal end cap
assembly 61 having two o-rings 70 contained in separate grooves 68.
The amount of circumferential compression in the o-ring as
installed, as well the o-ring material and physical
characteristics, may also vary depending on service requirements of
the system. The size and characteristics of the o-ring is
preferably designed to maximize the stored energy in the resilient
ring of the metal end cap seal.
[0027] The embodiments set forth herein are merely illustrative and
do not limit the scope of the invention or the details therein. It
will be appreciated that many other modifications and improvements
to the disclosure herein may be made without departing from the
scope of the invention or the inventive concepts herein disclosed.
Because many varying and different embodiments may be made within
the scope of the inventive concept herein taught, including
equivalent structures or materials hereafter thought of, and
because many modifications may be made in the embodiments herein
detailed in accordance with the descriptive requirements of the
law, it is to be understood that the details herein are to be
interpreted as illustrative and not in a limiting sense.
* * * * *