Note: Descriptions are shown in the official language in which they were submitted.
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HIGH PRESSURE SEAL BACK-UP
BACKGROUND
[0001] The field of the invention relates to seal back-ups for wellbore
tools often used in oil
and gas well applications. Sealing members engage movable members in wellbore
tools. Seal
back-ups provide support for the sealing members as well as attempt to reduce
an extrusion gap.
When under pressure, sealing members can extend through the extrusion gap when
making sealing
contact. During this time, standard seals can fall through the extrusion gap
and limit the amount of
the seal surface area engaging an outer surface to form a sealing engagement.
Additionally,
standard seals can shear and cause fragments of the seal to fall through the
extrusion gap (often
called the nibbling effect). Over time, prolonged nibbling can cause premature
failure of the seal.
SUMMARY
[0002] In an embodiment, a seal mechanism for use with a downhole component
comprises a
first tubular member and a second tubular member, wherein the first tubular
member is disposed
within the second tubular member and separated therefrom by an extrusion gap;
a circumferential
groove disposed on the first tubular member; a seal disposed within the
circumferential groove,
wherein the seal is selectively positionable into engagement with the second
tubular member; and a
high pressure seal back-up disposed within the circumferential groove, wherein
the distance
between an inside diameter of the high pressure seal back-up and an outside
diameter of the high
pressure seal back-up is configured to remain substantially constant when
pressure increases on the
high pressure seal back-up, and wherein the high pressure seal back-up is
configured to have an
increase in its outer diameter in response to a pressure increase.
[0003] In an embodiment, a high pressure seal mechanism for use with a
downhole component
in a wellbore environment comprises a tubular member and a surface, where the
tubular member is
disposed adjacent to the surface and separated from the surface by an
extrusion gap, a
circumferential groove disposed on the tubular member, a seal disposed within
the circumferential
groove, where the seal is selectively positionable into an engagement with the
surface, and a high
pressure seal back-up disposed within the circumferential groove, where the
distance between an
inside diameter of the high pressure seal back-up and an outside diameter of
the high pressure seal
back-up is configured to remain substantially constant when pressure increases
on the high
pressure seal back-up.
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[0004] In another embodiment, a method comprises increasing pressure on a
seal and a high
pressure seal back-up, where the seal and high pressure seal back-up are
disposed with a
circumferential groove, extending the high pressure seal back-up into an
extrusion gap, and
forming a seal between a tubular member and a surface.
[0005] These and other features will be more clearly understood from the
following detailed
description taken in conjunction with the accompanying drawings and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] For a more complete understanding of the present disclosure and the
advantages
thereof, reference is now made to the following brief description, taken in
connection with the
accompanying drawings and detailed description:
[0007] Figure 1 is a cut-away view of an embodiment of a wellbore servicing
system.
[0008] Figure 2A is a side view of an embodiment of a high pressure seal
mechanism.
[0009] Figure 2B is a cross-section view of an embodiment of a high
pressure seal mechanism.
[0010] Figure 3A is a side view of an embodiment of a high pressure seal
back-up.
[0011] Figure 3B is a side view of an embodiment of a standard seal back-
up.
[0012] Figure 4A is another cross-section view of an embodiment of a high
pressure seal
mechanism.
[0013] Figure 4B is cross-section view of an embodiment of a high pressure
seal back-up.
[0014] Figure 5A is a cross-section view of an embodiment of a standard
seal mechanism.
[0015] Figure 5B is a cross-section view of an embodiment of a seal in a
standard seal
mechanism.
[0016] Figure 5C is cross-section view of an embodiment of a standard seal
back-up and a seal
in a standard seal mechanism.
[0017] Figure 6 is another cross-section view of an embodiment of a high
pressure seal
mechanism.
[0018] Figure 7 is another cross-section view of an embodiment of a high
pressure seal
mechanism.
[0019] Figure 8 is another cross-section view of an embodiment of a high
pressure seal
mechanism.
[0020] Figure 9 is another cross-section view of an embodiment of a high
pressure seal
mechanism.
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DETAILED DESCRIPTION OF THE EMBODIMENTS
[0021] In the drawings and description that follow, like parts are
typically 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 conventional elements
may not be shown
in the interest of clarity and conciseness. Specific embodiments are described
in detail and are
shown in the drawings, 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. It is to be fully recognized that the
different teachings of the
embodiments discussed infra may be employed separately or in any suitable
combination to
produce desired results.
[0022] Unless otherwise specified, any use of any form of the terms
"connect," "engage,"
"couple," "attach," or any other term describing an interaction between
elements is not meant to
limit the interaction to direct interaction between the elements and may also
include indirect
interaction between the elements described. In the following discussion and in
the claims, the
terms "including" and "comprising" are used in an open-ended fashion, and thus
should be
interpreted to mean "including, but not limited to ...". Reference to up or
down will be made for
purposes of description with "up," "upper," "upward," or "upstream" meaning
toward the surface
of the wellbore and with "down," "lower," "downward," or "downstream" meaning
toward the
terminal end of the well, regardless of the wellbore orientation. Reference to
in or out will be
made for purposes of description with "in," "inner," or "inward" meaning
toward the center or
central axis of the wellbore, and with "out," "outer," or "outward" meaning
toward the wellbore
tubular and/or wall of the wellbore. Reference to "longitudinal,"
"longitudinally," or "axially"
means a direction substantially aligned with the main axis of the wellbore
and/or wellbore tubular.
Reference to "radial" or "radially" means a direction substantially aligned
with a line between the
main axis of the wellbore and/or wellbore tubular and the wellbore wall that
is substantially normal
to the main axis of the wellbore and/or wellbore tubular, though the radial
direction does not have
to pass through the central axis of the wellbore and/or wellbore tubular. The
various characteristics
mentioned above, as well as other features and characteristics described in
more detail below, will
be readily apparent to those skilled in the art with the aid of this
disclosure upon reading the
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following detailed description of the embodiments, and by referring to the
accompanying
drawings.
[0023] Several tools used in a servicing operation may comprise one or more
high pressure
seal mechanisms configured to engage one or more other components. For
example, a completion
tool and/or a retrieval tool may comprise a piston having a high pressure seal
mechanism. The
component may be fixedly attached to the tool. A tool comprising a high
pressure seal mechanism
may comprise a seal to engage a surface in the wellbore. This seal may be
disposed in a
circumferential groove, and the circumferential groove may be disposed
circumferentially on a
surface of a portion of the wellbore tool. Traditional seal back-ups may be
used in seals to help
maintain the seal under high pressure. However, traditional back-ups do not
extend into the
extrusion gap, leading to potential leaks and loss of integrity of the seal.
In order to address this
potential problem, the high pressure seal back-up disclosed herein extends
into the extrusion gap
under pressure, supporting the seal in the extrusion gap when the seal is
under pressure. The high
pressure seal mechanism may comprise a high pressure seal back-up disposed
with the
circumferential groove and configured so that the distance between the inside
diameter of the high
pressure seal back-up and the outside diameter of the high pressure seal back-
up remain
substantially constant when pressure increases on the high pressure seal back-
up. As used herein,
"high pressure" means greater than or equal to about 500 pounds per square
inch, greater than or
equal to about 1,000 pounds per square inch, greater than or equal to about
5,000 pounds per
square inch, or greater or equal to about 10,000 pounds per square inch. One
of ordinary skill in
the art would understand, with the aid of this disclosure, when a "high
pressure" scenario exists
based on, for example, the operational conditions, the service environment,
the type of seal, or any
safety concerns. For example, a "high pressure" scenario may exist, which may
require a high
pressure seal back-up, when there is a need for a standard seal back-up. While
described in terms
of a high pressure seal back-up and a high pressure seal system in some
embodiments, the systems
and methods described herein may also be used at pressures less than those
considered high
pressure.
100241 When the high pressure seal mechanism is under high pressure, the
seal extends from
the groove, into the extrusion gap, and engages an outside surface. The high
pressure seal back-up
may also extend from the groove and into the extrusion gap. The high pressure
seal back-up may
engage the seal in the extrusion gap, supporting the seal in the extrusion
gap, and preventing the
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seal from falling into the extrusion gap. Preventing the seal from falling
into the extrusion gap
facilitates a better sealing engagement between the tool and outside surface.
Additionally, this
feature may also relieve pressure between the seal and the edge of, for
example, the circumferential
groove or a second seal back-up, reducing any shear force on the seal, and
potentially extending
the life of the seal.
[0025] As further disclose herein, the high pressure sealing mechanism may
comprise a
plurality of second seal back-ups and a plurality of high pressure seal back-
ups. The plurality of
second seal back-ups and the plurality of high pressure seal back-ups provide
support for the seal
in the circumferential groove. In one embodiment, a plurality of second seal
back-ups and a
plurality of high pressure seal back-ups are configured to make the high
pressure seal mechanism
a two-way seal. In another embodiment, a plurality of second seal back-ups and
a plurality of
high pressure seal back-ups are configured to make the high pressure seal
mechanism a one-way
seal. Additionally, the high pressure seal back-up may have a plurality of
locking teeth
extending outwardly from the high pressure seal back-up and configured to
engage with a
plurality of locking teeth extending outwardly from a surface adjacent to the
high pressure seal
back-up. In some embodiments, a wedge may be fixedly attached to a surface
adjacent to the
high pressure seal back-up. These features may limit the reduction of the
outside diameter of the
high pressure seal back-up when pressure decreases on the high pressure seal
back-up. Further
features may keep the high pressure seal back-up in the extrusion gap when,
for example, there is
a sudden drop in differential pressure followed quickly by a rise in
differential pressure where
otherwise the seal might fall into the extrusion gap before the high pressure
seal back-up has
time to move back into the extrusion gap and prevent the seal from falling
through the extrusion
gap.
[0026] Turning to Figure 1, an example of a wellbore operating environment
in which one or
more high pressure seal mechanisms may be used is shown. As depicted, the
operating
environment comprises a drilling rig 106 that is positioned on the earth's
surface 104 and
extends over and around a wellbore 114 that penetrates a subterranean
formation 102 for the
purpose of recovering hydrocarbons. The wellbore 114 may be drilled into the
subterranean
formation 102 using any suitable drilling technique. The wellbore 114 extends
substantially
vertically away from the earth's surface 104 over a vertical wellbore portion
116, deviates from
vertical relative to the earth's surface 104 over a deviated wellbore portion
136, and transitions to
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a horizontal wellbore portion 118. In alternative operating environments, all
or portions of a
wellbore may be vertical, deviated at any suitable angle, horizontal, and/or
curved. The wellbore
may be a new wellbore, an existing wellbore, a straight wellbore, an extended
reach wellbore, a
sidetracked wellbore, a multi-lateral wellbore, and other types of wellbores
for drilling and
completing one or more production zones. Further the wellbore may be used for
both producing
wells and injection wells. In an embodiment, the wellbore may be used for
purposes other than
or in addition to hydrocarbon production, such as uses related to geothermal
energy and/or the
production of water (e.g., potable water).
100271 A wellbore tubular string comprises a seal mechanism may be lowered
into the
subterranean formation 102 for a variety of drilling, completion, workover,
and/or treatment
procedures throughout the life of the wellbore. The embodiment shown in Figure
1 illustrates
the wellbore tubular 120 in the form of a completion string being lowered into
the subterranean
formation. It should be understood that the wellbore tubular 120 is equally
applicable to any
type of wellbore tubular being inserted into a wellbore, including as non-
limiting examples drill
pipe, production tubing, rod strings, and coiled tubing. In the embodiment
shown in Figure. 1,
the wellbore tubular 120 comprising the high pressure seal mechanism may be
conveyed into the
subterranean formation 102 in a conventional manner and may subsequently be
used to provide a
seal within the wellbore as described herein.
[0028] The drilling rig 106 comprises a derrick 108 with a rig floor 110
through which the
wellbore tubular 120 extends downward from the drilling rig 106 into the
wellbore 114. The
drilling rig 106 comprises a motor driven winch and other associated equipment
for extending
the wellbore tubular 120 into the wellbore 114 to position the wellbore
tubular 120 at a selected
depth. While the operating environment depicted in Figure 1 refers to a
stationary drilling rig 106
for lowering and setting the wellbore tubular 120 comprising the seal
mechanism within a land-
based wellbore 114, in alternative embodiments, mobile workover rigs, wellbore
servicing units
(such as coiled tubing units), and the like may be used to lower the wellbore
tubular 120 comprising
the seal mechanism into a wellbore. It should be understood that a wellbore
tubular 120
comprising the seal mechanism may alternatively be used in other operational
environments, such
as within an offshore wellbore operational environment. In alternative
operating environments, a
vertical, deviated, or horizontal wellbore portion may be cased and cemented
and/or portions of
the wellbore may be uncased.
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[0029] Regardless of the type of operational environment in which the high
pressure seal
mechanism 200 is used, it will be appreciated that the high pressure seal
mechanism 200 serves
to provide a seal between two components. The high pressure seal mechanism 200
may utilize
different configurations than a standard seal mechanism. As described in
greater detail below
with respect to Figures 2A and 2B, the high pressure seal mechanism 200
generally comprises a
first tubular member 202 and a second tubular member 204, a circumferential
groove 206, a seal
208, and a high pressure seal back-up 210. The circumferential groove 206 is
disposed on the
first tubular member 202. The first tubular member 202 and second tubular
member 204 are
separated by an extrusion gap 212. The seal 208 may be disposed within the
circumferential
groove 206 so that the seal 208 is selectively positionable into engagement
with the second
tubular member 204. The high pressure seal back-up 210 may be disposed at
least partially
within the circumferential grove 206 so that when pressure increases on the
high pressure seal
back-up 210 the outer diameter of the high pressure seal back-up 210 increases
while the
distance between an inside diameter of the high pressure seal back-up 210 and
an outside
diameter of the high pressure seal back-up 210 remain substantially constant.
[0030] Figure 2A illustrates a side view of the high pressure seal
mechanism 200, and Figure
2B illustrates the same embodiment of the high pressure seal mechanism 200 in
cross-section.
As shown in Figures 2A and 2B, an embodiment of the high pressure seal
mechanism 200
comprises a first tubular member 202 and a second tubular member 204, the
first tubular member
202 and the second tubular member 204 are separated by an extrusion gap 212.
The second
tubular member 204 may also be a flat surface, a surface such as a bore,
(e.g., in a wall of a
component, within a tubular member, etc.) or any other type of surface as long
as an extrusion
gap 212 exists between the first tubular member 202 and the second tubular
member 204. A
circumferential groove 206 is disposed on the first tubular member 202. The
circumferential
groove 206 may be disposed radially, for example, on the first tubular member
202 such that the
circumferential groove 206 extends perpendicular to the longitudinal axis of
the first tubular
member 202. In an embodiment, the circumferential groove 206 may extend at a
non-
perpendicular angle to the longitudinal axis of the first tubular member 202.
In an embodiment,
the circumferential groove 206 may also be disposed elliptically, for example,
such that the
distance from the center point of the circumferential groove 206 on the
longitudinal axis of the
first tubular member 202 to the circumferential groove 206 is not constant.
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[0031] A seal 208 is disposed with the circumferential groove 206. The seal
208 may be an
o-ring, for example, or it may be any other member that could provide a seal
between the first
tubular member 202 and the second tubular member 204. The seal 208 may rest
inside, on, or
adjacent to the circumferential groove 206. When pressure is not applied, the
seal 208 may sit
inside the circumferential groove 206 without extending radially into the
extrusion gap 212, the
seal 208 may at least partially extend into the extrusion gap 212, or the seal
208 may engage the
second tubular member 204.
[0032] A high pressure seal back-up 210 is disposed with the
circumferential groove 206.
The high pressure seal back-up 210 may rest inside, on, or adjacent to the
circumferential groove
206. When pressure is not applied, the high pressure seal back-up 210 may sit
inside the
circumferential groove 206 without extending radially into the extrusion gap
212, or the high
pressure seal back-up 210 may at least partially extend radially into the
extrusion gap 212. As
shown in Figure 3A and Figure 3B, an embodiment of the high pressure seal back-
up 210,
depicted in Figure 3A, depicts how the high pressure seal back-up 210 has two
main faces that
generally face in the direction that a normal force would be applied as shown.
The main faces of
the high pressure seal back-up 210 are such that they are located on at least
two planes which
intersect when pressure is not applied to the main faces of the high pressure
seal back-up 210.
When under pressure, the high pressure seal back-up 210 may partially flatten
out and radially
expand. In an embodiment, the high pressure seal back-up 210 may at radially
expand by at least
about 1%, at least about 2%, at least about 3%, at least about 4%, at least
about 5%, at least
about 6%, at least about 7%, at least about 8%, at least about 9%, or at least
about 10% of the
outer radius of the high pressure seal back-up 210 in an uncompressed and un-
expanded state. In
an embodiment, the inside and outside diameters of the high pressure seal back-
up 210 may
increase when axially compressed. When under pressure, the high pressure seal
back-up 210
may flatten out and the inside and outside diameters of the high pressure seal
back-up 210 may
increase. This feature of the high pressure seal back-up 210 allows the
distance between an
inside diameter of the high pressure seal back-up 210 and an outside diameter
of the high
pressure seal back-up 210 to remain substantially constant when the high
pressure seal back-up
210 is under high pressure. In an embodiment of the high pressure seal back-up
210, the high
pressure seal back-up 210 comprises a wave spring, which can comprise any ring
having one or
more wave-like features and/or radially expands upon being axially compressed.
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[0033] Conversely, Figure 3B depicts how a standard seal back-up has two
main faces that
generally face in the direction that a normal force would be applied as shown.
However, the
main faces of the standard seal back-up are such that they are located on
parallel planes. In this
configuration, the outside and inside diameter of the high pressure seal back-
up 210 remain
substantially constant even when a load is applied. This configuration relies
more heavily on the
elastic or inelastic malleable characteristics of its composition under a
normal force.
[0034] The various components of the sealing mechanism (e.g., the high
pressure seal back-
up) may be formed from materials selected to withstand downhole conditions
including heat
and/or various acidic or basic fluids. Examples of suitable materials may
include, but are not
limited to, fluoropolymers, polyethylene polymers, silicone polymers, urethane
polymers, and
any combination thereof. Nonlimiting examples of suitable elastomeric
compounds include,
ethylene propylene diene monomer (EPDM), fluoro el astomers (FKM) [Vi ton ],
perfluoroelastomers (FFKM) [Kalrez0, Chemraze, Zalake], flouoropolymer
elastomers
[Vitont], polytetrafluoroethylene, copolymer of tetrafluoroethylene and
propylene (FEPM)
[Aflas0], and polyetheretherketone (PEEK), polyetherketone (PEK), polyamide-
imide (PAI),
polyimide [Vespe18], polyphenylene sulfide (PPS), and any combination thereof.
In addition to
these components, various metals suitable for use in forming the high pressure
seal back-up may
be used (e.g., spring steel and the like). In an embodiment, metals that
experience plastic
deformation may be used when, for example, the seal back-up does not need to
act as a dynamic
seal. Various other components may be used in combination with any of the
listed materials.
[0035] As shown in Figure 4A, another embodiment of the high pressure seal
mechanism
200 depicts the high pressure seal mechanism 200 under a pressure
differential. In this
embodiment, the seal 208 acting under a normal force created by the
differential pressure (e.g., a
higher pressure on the right of the seal 208 than on the left of the seal 208
in Figure 4A) extends
into the extrusion gap 212 engaging the second tubular member 204.
Additionally, the high
pressure seal back-up 210 acting under a normal force created by the
differential pressure
expands and extends into the extrusion gap 212 while keeping the distance
between the inside
diameter of the high pressure seal back-up 210 and the outside diameter of the
high pressure seal
back-up 210 substantially constant relative to the distance between the inside
diameter of the
high pressure seal back-up 210 and the outside diameter of the high pressure
seal back-up 210
when pressure is not applied. As a normal force is applied to the high
pressure seal back-up 210,
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the inside diameter of the high pressure seal back-up 210 begins to move a
distance 404 from the
base of circumferential groove 206. At the same time, the outside diameter of
the high pressure
seal back-up 210 begins to move a distance 404 into the extrusion gap. As a
normal force is
applied to the high pressure seal back-up 210 the distances 402 and 404 are
substantially the
same. The high pressure seal back-up 210 engages both the wall of the
circumferential groove
206 and the seal 208. This feature prevents the seal 208 from falling through
the extrusion gap
212 and engages more surface area of the seal 208 with the second tubular
member 204 creating
a stronger seal, as more closely shown in Figure 4B. This feature also
substantially reduces the
shearing and nibbling effect on the seal 208 by preventing the seal 208 from
falling through the
extrusion gap 212 and shearing the seal 208 with an edge. In another
embodiment, the high
pressure seal back-up 210 may also engage the second tubular member 204.
[0036] As shown in Figure 5A, another embodiment depicts the effect a
standard seal
mechanism 500 has on a seal 508 under a pressure differential. In this
embodiment, the seal 508
is allowed to extend through the extrusion gap 512 reducing the engagement
that could take
place between the seal 508 and the second tubular member 204, as shown in
Figure 5B, and
shearing the seal 508 producing a nibbling effect that accelerates the wear on
the seal 508, as
shown in Figure 5B. Unlike the high pressure seal back-up 210 in Figure 4A,
the standard seal
back-up 514 depicted in Figure 5A and Figure 5B relies more heavily on the
elastic or inelastic
malleable characteristics of its composition under a normal force and does not
substantially
extend into the extrusion gap 512. Thus, the standard back-up seal 514 may not
be as effective at
preventing the seal 508 from falling through the extrusion gap 512 as the high
pressure seal
back-up described herein.
[0037] As shown in Figure 6, another embodiment discloses a second seal
back-up 614
disposed adjacent to the seal 608 and adjacent to the high pressure seal back-
up 610. Although
in this embodiment the second seal back-up 614 is disposed between the high
pressure seal back-
up 610 and the seal 608, the second seal back-up 614 may also be positioned on
lower pressure
side from the high pressure seal back-up 610, a higher pressure side from the
seal 608, or
anywhere disposed with the circumferential groove 606. This configuration
provides extra
support in the circumferential groove 606 for the high pressure seal back-up
610 and the seal 608
and helps to provide a uniform force on the high pressure seal back-up 610
helping to uniformly
compress the high pressure seal back-up 610 in the axial direction. In this
embodiment, even
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though the second seal back-up 614 has a corner that appears to be similar to
the corner depicted
in Figure 5 and Figure 5B that would result in the nibbling effect, the high
pressure seal back-up
610 still prevents the seal 610 from falling through the extrusion gap 612 and
thus greatly
reduces the shearing between the second seal back-up 614 and the seal 608.
[0038] As shown in Figure 7, another embodiment discloses the use of a
plurality of high
pressure seal back-ups 710 as well as a plurality of second seal back-ups 714.
This configuration
provides extra support for the seal 708 in the circumferential groove 706. The
positions of the
seal 708, the plurality of high pressure seal back-ups 710, and the plurality
of second seal back-
ups 714 may be disposed in any combination with the circumferential groove
706. Furthermore,
in this embodiment and other similar embodiments the high pressure seal
mechanism 700 may be
a two-way seal. In general, a two-way seal comprises a seal configured to
maintain a pressure
differential in a first direction that is substantially similar to a pressure
differential in a second
direction. In other embodiments, the high pressure seal mechanism may be a one-
way seal. In
general, a one-way seal comprises a seal configured to maintain a first
pressure differential in a
first direction and a second differential in a second direction, where the
first pressure differential
and the second pressure differential are different. For example, when a high
pressure seal back-
up is disposed on only one side of a seal, the seal may maintain a seal at a
higher pressure
differential when the higher pressure is applied to the seal side than when
the higher pressure is
applied to the high pressure seal back-up side. When the pressure is applied
to the high pressure
seal back-up side, the pressure may bias the high pressure seal back-up away
from the wall of the
groove and not axially compress the high pressure seal back-up.
[0039] As shown in Figure 8, another embodiment discloses a plurality of
locking teeth 816
extending outwardly from the high pressure seal back-up 810 and configured to
engage with a
plurality of locking teeth 816 extending outwardly from a surface adjacent to
the high pressure
seal back-up 810. Figure 8 depicts the plurality of locking teeth 816 engaging
the high pressure
seal back-up 810 with the second seal back-up 814. However, the plurality of
locking teeth 818
may engage the high pressure seal back-up 810 with any surface disposed with
the
circumferential groove 806 including the wall of the circumferential groove
806. The plurality
of locking teeth 816 are configured to limit the reduction of the outside
diameter of the high
pressure seal back-up 810 when pressure decreases. This configuration keeps
the high pressure
seal back-up 810 in the extrusion gap 812 when, for example, there is a sudden
drop in
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differential pressure followed quickly by a rise in differential pressure
where otherwise the seal
808 might fall into the extrusion gap 812 before the high pressure seal back-
up 810 has time to
move back into the extrusion gap 812 and prevent the seal 808 from falling
through the extrusion
gap 812. When pressure decreases across the high pressure seal mechanism 800,
the plurality of
locking teeth 816 prolong the time the high pressure seal back-up 810 remains
extended into the
extrusion gap 812 before the high pressure seal back-up 810 resets into the
low pressure
condition. When the high pressure seal back-up 810 axially expands, it may no
longer fully
engage the locking teeth 816 and may eventually disengage from the locking
teeth 816 upon a
sufficient amount of axial expansion. Once the plurality of locking teeth 816
are no longer
engaged, the high pressure seal back-up 810 contracts into the circumferential
grove 806 and into
the low pressure condition.
[0040] As shown in Figure 9, another embodiment discloses a wedge 918
fixedly attached to
a second surface adjacent to the high pressure seal back-up 910 and configured
to limit the
reduction on the outside diameter of the high pressure seal back-up 910 when
pressure decreases
on the high pressure seal back-up 910. Figure 9, depicts the wedge 918 fixedly
attached to a
second seal back-up 914, however, the wedge 918 can be fixedly attached to any
surface
disposed with the circumferential groove 906 and adjacent to the high pressure
seal back-up 910.
The wedge configuration keeps the high pressure seal back-up 910 in the
extrusion gap 912
when, for example, there is a sudden drop in differential pressure followed
quickly by a rise in
differential pressure where otherwise the seal 908 might fall into the
extrusion gap 912 before
the high pressure seal back-up 910 has time to move back into the extrusion
gap 912 and prevent
the seal 908 from falling through the extrusion gap 912. When pressure
decreases across the
high pressure seal mechanism 900, the wedge 918 prolongs the time the high
pressure seal back-
up 910 remains extended into the extrusion gap 912 before the high pressure
seal back-up 910
resets into the low pressure condition. When the high pressure seal back-up
910 axially expands,
it may no longer fully engage the wedge 918 and may eventually disengage from
the wedge 918
upon a sufficient amount of axial expansion. Once the wedge 918 no longer
engages the high
pressure seal back-up 910, the high pressure seal back-up 910 contracts into
the circumferential
grove 906 and into the low pressure condition.
[0041] A seal mechanism may be assembled using any technique known in the
art. In an
embodiment, the seal mechanism may be assembled by first constructing the seal
mechanism on
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the first tubular member. A circumferential groove may be disposed on the
first tubular member
and a seal may be disposed at least partially within the circumferential
groove. For example, the
seal may comprise an elastomeric material that may be stretched and passed
over the first tubular
member before contracting into the groove A high pressure seal back-up may be
disposed at
least partially within the circumferential groove by compressing the high
pressure seal back-up
to radially expand both the inner and outer diameters, placing the high
pressure seal back-up
around the axis of the first tubular member so that the first tubular member
fits through the inside
diameter of the high pressure seal back-up, moving the high pressure seal back-
up along the axis
of first tubular member until it is radially positioned with the
circumferential groove, and
decompressing the high pressure seal back-up allowing the inside diameter of
the high pressure
seal back-up to contract. The first tubular member may then be disposed within
the second
tubular member. As an alternative to compressing the high-pressure seal back-
up during
installation, a cut (e.g., a radial cut) may be made in the high pressure seal
back-up to create a
gap in the high pressure seal back-up to allow the high pressure seal back-up
to expand. The
high pressure seal back-up may then be moved over the first tubular member.
Once the high
pressure seal back-up is radially in position with the circumferential groove,
the high pressure
seal back-up gap may contract, reducing the diameter of the high pressure seal
back-up, and
positioning the high pressure seal back-up at least partially within the
circumferential groove.
The further axial compression of the high pressure seal back-up during use may
serve to close
the cut.
[0042] In an embodiment, the seal mechanism may be used to form a seal
between two
surfaces. The pressure on the seal and the high pressure seal back-up may be
increased when the
seal and the high pressure seal back-up are disposed at least partially within
the circumferential
groove. The high pressure seal back-up may be extended into the extrusion gap,
and the seal
may engage a tubular member and a surface to form a sealing engagement between
the tubular
member and the surface. The high pressure seal back-up may extend into
extrusion gap in
response to an axial compression, which may result from the application of a
pressure
differential across the seal mechanism. As the high pressure seal back-up
expands, the distance
between an inside diameter of the high pressure seal back-up and an outside
diameter of the high
pressure seal back-up may remain substantially constant. The seal mechanism
may then maintain a
seal while the pressure differential is maintained across the seal mechanism.
In an embodiment, the
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high pressure seal back-up may extend into the extrusion gap and contact the
surface, thereby
forming an engagement between both the tubular member and the surface. In some
embodiments,
locking teeth may be used. In this configuration, the locking teeth on the
high pressure seal back-up
may engage the corresponding features on an adjacent surface (which may
comprise one-way
features), thereby preventing the high pressure seal back-up from radially
contracting until the
pressure differential has fallen below a threshold. In some embodiments, a
wedge disposed on an
adjacent surface to the high pressure seal back-up may be used. In this
configuration, the wedge on
the adjacent surface may engage the high pressure seal back-up, thereby
preventing the high
pressure seal back-up from radially contracting until the pressure
differential has fallen below a
threshold.
[0043] When the pressure differential across the seal mechanism decreases,
the high pressure
seal back-up may radially contract away from the surface while maintaining a
substantially
constant distance between an outside diameter of the high pressure seal back-
up and an inside
diameter of the high pressure seal back-up. In an embodiment, the high
pressure seal back-up
may contract out of the extrusion gap. When a wedge is used on an adjacent
surface to the high
pressure seal back-up, the wedge may slow the reduction of the outside
diameter of the high
pressure seal back-up when pressure decreases on the high pressure seal back-
up. Similarly when
one or more locking features are used on an adjacent surface to the high
pressure seal back-up,
the locking features may slow the reduction of the outside diameter of the
high pressure seal back-
up when pressure decreases on the high pressure seal back-up. Once the
pressure differential
across the seal mechanism has fallen below a threshold, the high pressure seal
back-up may
axially expand and disengage from any locking features, thereby allowing the
high pressure seal
back-up to contract into the circumferential groove. The
pressurization/depressurization cycle
may be repeated any number of times and the seal mechanism may be used to form
a seal across
the extrusion gap.
[0044] At least one embodiment is disclosed and variations, combinations,
and/or
modifications of the embodiment(s) and/or features of the embodiment(s) made
by a person
having ordinary skill in the art are within the scope of the disclosure.
Alternative embodiments
that result from combining, integrating, and/or omitting features of the
embodiment(s) are also
within the scope of the disclosure. Where numerical ranges or limitations are
expressly stated,
such express ranges or limitations should be understood to include iterative
ranges or limitations
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of like magnitude falling within the expressly stated ranges or limitations
(e.g., from about 1 to
about 10 includes, 2, 3,4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13,
etc.). For example,
whenever a numerical range with a lower limit, Rh and an upper limit, Rõ, is
disclosed, any
number falling within the range is specifically disclosed. In particular, the
following numbers
within the range are specifically disclosed: R=Ri+k*(Ru-R1), wherein k is a
variable ranging
from 1 percent to 100 percent with a 1 percent increment, i.e., k is 1
percent, 2 percent, 3 percent,
4 percent, 5 percent, ..., 50 percent, 51 percent, 52 percent, ..., 95
percent, 96 percent, 97
percent, 98 percent, 99 percent, or 100 percent. Moreover, any numerical range
defined by two
R numbers as defined in the above is also specifically disclosed. Use of the
term "optionally"
with respect to any clement of a claim means that the element is required, or
alternatively, the
element is not required, both alternatives being within the scope of the
claim. Use of broader
terms such as comprises, includes, and having should be understood to provide
support for
narrower terms such as consisting of, consisting essentially of, and comprised
substantially of.
Accordingly, the scope of protection is not limited by the description set out
above but is defined
by the claims that follow, that scope including all equivalents of the subject
matter of the claims.
Each and every claim is incorporated as further disclosure into the
specification and the claims
are embodiment(s) of the present invention.
