HIGH PRESSURE SEAL BACK-UP

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.

DETAILED DESCRIPTION OF THE EMBODIMENTS

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.

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 following detailed description of the embodiments, and by referring to the accompanying drawings.

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.

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 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.

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.

Turning toFIG. 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 rig106that is positioned on the earth's surface104and extends over and around a wellbore114that penetrates a subterranean formation102for the purpose of recovering hydrocarbons. The wellbore114may be drilled into the subterranean formation102using any suitable drilling technique. The wellbore114extends substantially vertically away from the earth's surface104over a vertical wellbore portion116, deviates from vertical relative to the earth's surface104over a deviated wellbore portion136, and transitions to a horizontal wellbore portion118. 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).

A wellbore tubular string comprises a seal mechanism may be lowered into the subterranean formation102for a variety of drilling, completion, workover, and/or treatment procedures throughout the life of the wellbore. The embodiment shown inFIG. 1illustrates the wellbore tubular120in the form of a completion string being lowered into the subterranean formation. It should be understood that the wellbore tubular120is 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 inFIG. 1, the wellbore tubular120comprising the high pressure seal mechanism may be conveyed into the subterranean formation102in a conventional manner and may subsequently be used to provide a seal within the wellbore as described herein.

The drilling rig106comprises a derrick108with a rig floor110through which the wellbore tubular120extends downward from the drilling rig106into the wellbore114. The drilling rig106comprises a motor driven winch and other associated equipment for extending the wellbore tubular120into the wellbore114to position the wellbore tubular120at a selected depth. While the operating environment depicted inFIG. 1refers to a stationary drilling rig106for lowering and setting the wellbore tubular120comprising the seal mechanism within a land-based wellbore114, in alternative embodiments, mobile workover rigs, wellbore servicing units (such as coiled tubing units), and the like may be used to lower the wellbore tubular120comprising the seal mechanism into a wellbore. It should be understood that a wellbore tubular120comprising 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.

Regardless of the type of operational environment in which the high pressure seal mechanism200is used, it will be appreciated that the high pressure seal mechanism200serves to provide a seal between two components. The high pressure seal mechanism200may utilize different configurations than a standard seal mechanism. As described in greater detail below with respect toFIGS. 2A and 2B, the high pressure seal mechanism200generally comprises a first tubular member202and a second tubular member204, a circumferential groove206, a seal208, and a high pressure seal back-up210. The circumferential groove206is disposed on the first tubular member202. The first tubular member202and second tubular member204are separated by an extrusion gap212. The seal208may be disposed within the circumferential groove206so that the seal208is selectively positionable into engagement with the second tubular member204. The high pressure seal back-up210may be disposed at least partially within the circumferential grove206so that when pressure increases on the high pressure seal back-up210the outer diameter of the high pressure seal back-up210increases while the distance between an inside diameter of the high pressure seal back-up210and an outside diameter of the high pressure seal back-up210remain substantially constant.

FIG. 2Aillustrates a side view of the high pressure seal mechanism200, andFIG. 2Billustrates the same embodiment of the high pressure seal mechanism200in cross-section. As shown inFIGS. 2A and 2B, an embodiment of the high pressure seal mechanism200comprises a first tubular member202and a second tubular member204, the first tubular member202and the second tubular member204are separated by an extrusion gap212. The second tubular member204may 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 gap212exists between the first tubular member202and the second tubular member204. A circumferential groove206is disposed on the first tubular member202. The circumferential groove206may be disposed radially, for example, on the first tubular member202such that the circumferential groove206extends perpendicular to the longitudinal axis of the first tubular member202. In an embodiment, the circumferential groove206may extend at a non-perpendicular angle to the longitudinal axis of the first tubular member202. In an embodiment, the circumferential groove206may also be disposed elliptically, for example, such that the distance from the center point of the circumferential groove206on the longitudinal axis of the first tubular member202to the circumferential groove206is not constant.

A seal208is disposed with the circumferential groove206. The seal208may be an o-ring, for example, or it may be any other member that could provide a seal between the first tubular member202and the second tubular member204. The seal208may rest inside, on, or adjacent to the circumferential groove206. When pressure is not applied, the seal208may sit inside the circumferential groove206without extending radially into the extrusion gap212, the seal208may at least partially extend into the extrusion gap212, or the seal208may engage the second tubular member204.

A high pressure seal back-up210is disposed with the circumferential groove206. The high pressure seal back-up210may rest inside, on, or adjacent to the circumferential groove206. When pressure is not applied, the high pressure seal back-up210may sit inside the circumferential groove206without extending radially into the extrusion gap212, or the high pressure seal back-up210may at least partially extend radially into the extrusion gap212. As shown inFIG. 3AandFIG. 3B, an embodiment of the high pressure seal back-up210, depicted inFIG. 3A, depicts how the high pressure seal back-up210has 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-up210are 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-up210. When under pressure, the high pressure seal back-up210may partially flatten out and radially expand. In an embodiment, the high pressure seal back-up210may 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-up210in an uncompressed and un-expanded state. In an embodiment, the inside and outside diameters of the high pressure seal back-up210may increase when axially compressed. When under pressure, the high pressure seal back-up210may flatten out and the inside and outside diameters of the high pressure seal back-up210may increase. This feature of the high pressure seal back-up210allows the distance between an inside diameter of the high pressure seal back-up210and an outside diameter of the high pressure seal back-up210to remain substantially constant when the high pressure seal back-up210is under high pressure. In an embodiment of the high pressure seal back-up210, the high pressure seal back-up210comprises a wave spring, which can comprise any ring having one or more wave-like features and/or radially expands upon being axially compressed.

Conversely,FIG. 3Bdepicts 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-up210remain 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.

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), fluoroelastomers (FKM) [Viton®], perfluoroelastomers (FFKM) [Kalrez®, Chemraz®, Zalak®], flouoropolymer elastomers [Viton®], polytetrafluoroethylene, copolymer of tetrafluoroethylene and propylene (FEPM) [Aflas®], and polyetheretherketone (PEEK), polyetherketone (PEK), polyamide-imide (PAI), polyimide [Vespel®], 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.

As shown inFIG. 4A, another embodiment of the high pressure seal mechanism200depicts the high pressure seal mechanism200under a pressure differential. In this embodiment, the seal208acting under a normal force created by the differential pressure (e.g., a higher pressure on the right of the seal208than on the left of the seal208inFIG. 4A) extends into the extrusion gap212engaging the second tubular member204. Additionally, the high pressure seal back-up210acting under a normal force created by the differential pressure expands and extends into the extrusion gap212while keeping the distance between the inside diameter of the high pressure seal back-up210and the outside diameter of the high pressure seal back-up210substantially constant relative to the distance between the inside diameter of the high pressure seal back-up210and the outside diameter of the high pressure seal back-up210when pressure is not applied. As a normal force is applied to the high pressure seal back-up210, the inside diameter of the high pressure seal back-up210begins to move a distance404from the base of circumferential groove206. At the same time, the outside diameter of the high pressure seal back-up210begins to move a distance404into the extrusion gap. As a normal force is applied to the high pressure seal back-up210the distances402and404are substantially the same. The high pressure seal back-up210engages both the wall of the circumferential groove206and the seal208. This feature prevents the seal208from falling through the extrusion gap212and engages more surface area of the seal208with the second tubular member204creating a stronger seal, as more closely shown inFIG. 4B. This feature also substantially reduces the shearing and nibbling effect on the seal208by preventing the seal208from falling through the extrusion gap212and shearing the seal208with an edge. In another embodiment, the high pressure seal back-up210may also engage the second tubular member204.

As shown inFIG. 5A, another embodiment depicts the effect a standard seal mechanism500has on a seal508under a pressure differential. In this embodiment, the seal508is allowed to extend through the extrusion gap512reducing the engagement that could take place between the seal508and the second tubular member204, as shown inFIG. 5B, and shearing the seal508producing a nibbling effect that accelerates the wear on the seal508, as shown inFIG. 5B. Unlike the high pressure seal back-up210inFIG. 4A, the standard seal back-up514depicted inFIG. 5AandFIG. 5Brelies more heavily on the elastic or inelastic malleable characteristics of its composition under a normal force and does not substantially extend into the extrusion gap512. Thus, the standard back-up seal514may not be as effective at preventing the seal508from falling through the extrusion gap512as the high pressure seal back-up described herein.

As shown inFIG. 6, another embodiment discloses a second seal back-up614disposed adjacent to the seal608and adjacent to the high pressure seal back-up610. Although in this embodiment the second seal back-up614is disposed between the high pressure seal back-up610and the seal608, the second seal back-up614may also be positioned on lower pressure side from the high pressure seal back-up610, a higher pressure side from the seal608, or anywhere disposed with the circumferential groove606. This configuration provides extra support in the circumferential groove606for the high pressure seal back-up610and the seal608and helps to provide a uniform force on the high pressure seal back-up610helping to uniformly compress the high pressure seal back-up610in the axial direction. In this embodiment, even though the second seal back-up614has a corner that appears to be similar to the corner depicted inFIG. 5andFIG. 5Bthat would result in the nibbling effect, the high pressure seal back-up610still prevents the seal610from falling through the extrusion gap612and thus greatly reduces the shearing between the second seal back-up614and the seal608.

As shown inFIG. 7, another embodiment discloses the use of a plurality of high pressure seal back-ups710as well as a plurality of second seal back-ups714. This configuration provides extra support for the seal708in the circumferential groove706. The positions of the seal708, the plurality of high pressure seal back-ups710, and the plurality of second seal back-ups714may be disposed in any combination with the circumferential groove706. Furthermore, in this embodiment and other similar embodiments the high pressure seal mechanism700may 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.

As shown inFIG. 8, another embodiment discloses a plurality of locking teeth816extending outwardly from the high pressure seal back-up810and configured to engage with a plurality of locking teeth816extending outwardly from a surface adjacent to the high pressure seal back-up810.FIG. 8depicts the plurality of locking teeth816engaging the high pressure seal back-up810with the second seal back-up814. However, the plurality of locking teeth818may engage the high pressure seal back-up810with any surface disposed with the circumferential groove806including the wall of the circumferential groove806. The plurality of locking teeth816are configured to limit the reduction of the outside diameter of the high pressure seal back-up810when pressure decreases. This configuration keeps the high pressure seal back-up810in the extrusion gap812when, for example, there is a sudden drop in differential pressure followed quickly by a rise in differential pressure where otherwise the seal808might fall into the extrusion gap812before the high pressure seal back-up810has time to move back into the extrusion gap812and prevent the seal808from falling through the extrusion gap812. When pressure decreases across the high pressure seal mechanism800, the plurality of locking teeth816prolong the time the high pressure seal back-up810remains extended into the extrusion gap812before the high pressure seal back-up810resets into the low pressure condition. When the high pressure seal back-up810axially expands, it may no longer fully engage the locking teeth816and may eventually disengage from the locking teeth816upon a sufficient amount of axial expansion. Once the plurality of locking teeth816are no longer engaged, the high pressure seal back-up810contracts into the circumferential grove806and into the low pressure condition.

As shown inFIG. 9, another embodiment discloses a wedge918fixedly attached to a second surface adjacent to the high pressure seal back-up910and configured to limit the reduction on the outside diameter of the high pressure seal back-up910when pressure decreases on the high pressure seal back-up910.FIG. 9, depicts the wedge918fixedly attached to a second seal back-up914, however, the wedge918can be fixedly attached to any surface disposed with the circumferential groove906and adjacent to the high pressure seal back-up910. The wedge configuration keeps the high pressure seal back-up910in the extrusion gap912when, for example, there is a sudden drop in differential pressure followed quickly by a rise in differential pressure where otherwise the seal908might fall into the extrusion gap912before the high pressure seal back-up910has time to move back into the extrusion gap912and prevent the seal908from falling through the extrusion gap912. When pressure decreases across the high pressure seal mechanism900, the wedge918prolongs the time the high pressure seal back-up910remains extended into the extrusion gap912before the high pressure seal back-up910resets into the low pressure condition. When the high pressure seal back-up910axially expands, it may no longer fully engage the wedge918and may eventually disengage from the wedge918upon a sufficient amount of axial expansion. Once the wedge918no longer engages the high pressure seal back-up910, the high pressure seal back-up910contracts into the circumferential grove906and into the low pressure condition.

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 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.

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 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.

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.