Packer seal for high-temperature and / or high-pressure environments

Abstract

A seal for a packer, adapted to be disposed in a casing in a wellbore, has an elastomeric ring defining a centre hole for receiving a mandrel of the packer therethrough. Expandable barriers are provided on opposing surfaces of the elastomeric ring and have cooperating sections that are independently bonded to the elastomeric ring, so that when the elastomeric ring is compressed longitudinally to expand the seal radially outward, the sections move radially outward. In this way, the elastomeric ring is constrained between the expandable barriers and the casing. The seal may be used to retrofit conventional packers.

Description

PACKER SEAL FOR HIGH-TEMPERATUREAND / OR HIGH-PRESSURE ENVIRONMENTSFIELD OF THE INVENTION

[0001] The present invention relates to the field of well construction, testing and maintenance, and, in particular, to well construction, testing and maintenance in deepwater environments.BACKGROUND OF THE INVENTION

[0002] Well construction, testing and maintenance often require suspension of the wellbore with a packer for isolating one part of a wellbore from another and / or for controlling the pressure in the well. The packer is typically deployed in the wellbore on a drill string. A component of the packer is a seal for filling a gap between the packer outside diameter and the casing internal diameter in the wellbore.

[0003] In conventional packers, the seal is energized to expand against a casing in the well by the weight of the drill string suspended under the packer. Cooperating with the mechanics of the packer system, the weight of the drill string compresses the seal so that it is pushed radially outward to the casing.

[0004] In early versions of the packer, the seal was inflatable. But, as described in Jansch (US6,443,458, 3 Sept 2002), a disadvantage of the inflatable packer is that they must have an uninflated diameter close to the inflated diameter to maintain seal integrity. This created challenges when a packer was passed through a smaller diameter tubular to a larger diameter tubular where the packer was to be deployed. Accordingly, Jansch proposed a packer having a rubber seal with metal fingers attached to the rubber by vulcanization. The seal deforms radially when subjected to axial pressure. The vulcanized fingers allow the seal to be retracted for withdrawal through the tubular after use.

[0005] The US regulator for offshore operations (the Bureau of Safety and Environmental Enforcement, or BSEE) allows for wells to be suspended during well operations, for example for repair of the subsea BOP (blowout preventer), installation of atubing head spool, and temporary sealing of a well for future interventions. The BSEE requires that a packer used for the suspension of the well must be rated for the temperature and differential pressure that the well generates.

[0006] Conventional packer systems use a rubber seal. The rubber seals typically are rated for maximum working pressures, among other criteria. Typically, as the casing diameter increases, the maximum working pressure decreases. For example, a packer seal that is rated for 10,000 psi when the casing diameter is in a range of from 2 to 7.75 inches will drop to a maximum working pressure rating of 5,000 psi at a casing diameter of 10.75 inches and to a maximum working pressure of 3,000 psi at a casing diameter of 12.75 inches (see for example, Halliburton H08344-DS published 2017 regarding the RTTS® Packer).

[0007] For applications where the wellbore pressure and / or temperature is high, for example in applications where temperatures exceed 180°F (82°C) and / or 10,000 psid (69,000 kPa), seal integrity may be adversely affected. In particular, the rubber used for the seal tends to soften at high temperatures and / or pressures such that it makes the rubber more fluid. The fluid rubber then flows downwardly, potentially leaving a void in the seal between the casing and the packer and compromising the well isolation.

[0008] Fripp et al. (US 11,634, 964B2 2023 Apr 25) relates to a swellable rubber element that also creates a cup packer. The apparatus has a mandrel, a packer and a spring positioned between the mandrel and an unconstrained swellable portion of the packer. The spring acts to urge the unconstrained portion away from the mandrel. The constrained portion of the packer is coupled to the mandrel.

[0009] Jakkula et al. (US11,473, 391B2 2022 Oct 18) discloses a packer sealing element having a non-swelling layer. The sealing element is disposed circumferentially about a mandrel. A non-swelling layer is bonded, for example by vulcanization, to the outer surface of the sealing element. Grooves are cut into the extremal diameter of the nonswelling layer to expose a portion of the cylindrical out surface of the sealing element to the outside of the non-swelling layer. The non-swelling layer is a non-swellable rubber, while the sealing element is made of a material that swells when exposed to water and water-based fluids.

[0010] Patel et al. (WO2023 / 076215A1 2023 May 4) provides a packer having a tubing, an expandable metal bladder secured around the tubing, and a sealing element mounted around the bladder. The seal moves into sealing engagement with a surrounding borehole wall when the expandable metal bladder is sufficiently expanded with internal pressure.

[0011] There remains a need for an improved seal for maintaining seal integrity under higher well pressures and / or temperatures.SUMMARY OF THE INVENTION

[0012] According to one aspect of the present invention, there is provided a seal for a packer, the packer adapted to be disposed in a casing in a wellbore, comprising: an elastomeric ring defining a centre hole with a longitudinal axis, the centre hole adapted to receive a mandrel of a packer therethrough, the elastomeric ring having opposing surfaces perpendicular to the longitudinal axis; and a first expandable barrier and a second expandable barrier on opposing surfaces of the elastomeric ring, the opposing surfaces being perpendicular to the longitudinal axis; each of the first expandable barrier and the second expandable barrier having cooperating sections that are independently bonded to the elastomeric ring, so that when the elastomeric ring is compressed longitudinally to expand the seal radially outward, the sections move radially outward, thereby constraining the elastomeric ring between the first expandable barrier, the second expandable barrier, and the casing.

[0013] According to another aspect of the present invention, there is provided a method for isolating a portion of a wellbore, comprising the steps of: providing a packer having a seal comprising: an elastomeric ring defining a centre hole with a longitudinal axis, the centre hole adapted to receive a mandrel of a packer therethrough, the elastomeric ring having opposing surfaces perpendicular to the longitudinal axis; and a first expandable barrier and a second expandable barrier on opposing surfaces of the elastomeric ring, the opposing surfaces being perpendicular to the longitudinal axis; each of the first expandable barrier and the second expandable barrier having cooperating sections that are independently bonded to the elastomeric ring; deploying the packer in a casing in the wellbore; and energizing the seal by longitudinally compressing the elastomeric ring toexpand the seal radially outward to contact the casing, thereby moving the cooperating sections radially outward to constrain the elastomeric ring between the first expandable barrier, the second expandable barrier, and the casing.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Certain embodiments of the disclosure will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood, however, that the accompanying figures illustrate the various implementations described herein and are not meant to limit the scope of various technologies described herein, and:

[0015] Figs. 1A and IB are side elevational and top plan views, respectively, of one embodiment of the seal of the present invention;

[0016] Figs. 2A and 2B are side elevational and top plan views, respectively, of the embodiment of Figs. 1A and IB when the seal is energized;

[0017] Figs. 3 A and 3B are side elevational and top plan views, respectively, of another embodiment of the seal of the present invention, while Fig. 3C is a top plan view of the seal of the embodiment of Figs. 3 A and 3B when the seal is energized;

[0018] Figs. 4A and 4B are top and side cross-sectional views, respectively, of a section of an expandable barrier of the embodiment of Figs. 3A - 3C;

[0019] Figs. 5A and 5B are schematic representations of the expandable barrier of the embodiment of Figs. 3A-3C before and after seal energization, respectively;

[0020] Figs. 6A and 6B are schematic representations of the expandable barrier of another embodiment of the embodiment of Figs. 3A-3C before and after seal energization, respectively;

[0021] Figs. 7A and 7B are side elevational and top plan views, respectively, of yet another embodiment of the seal of the present invention, while Fig. 7C is a top plan view of the seal of the embodiment of Figs. 7A and 7B when the seal is energized;

[0022] Figs. 8A and 8B are top and side cross-sectional views, respectively, of a section of an expandable barrier of the embodiment of Figs. 7A - 7C;

[0023] Figs. 9A and 9B are schematic representations of the expandable barrier of the embodiment of Figs. 7A - 7C before and after seal energization, respectively;

[0024] Figs. 10A and 10B are schematic representations of the expandable barrier of another embodiment of the embodiment of Figs. 7A-7C before and after seal energization, respectively;

[0025] Fig. 11A is a side elevation view of a further embodiment of the seal of the present invention before seal energization;

[0026] Fig. 1 IB is a cross-sectional view of the embodiment of Fig. 11A after seal energization; and

[0027] Fig. 12 illustrates the deployment of the seal of the present invention in one example of a conventional packer system.DETAILED DESCRIPTION OF THE INVENTION

[0028] The present invention provides an improved seal for a packer that is used in well construction, testing and maintenance. The packer is deployed in a casing in a wellbore. The seal has an elastomeric ring that is energized by longitudinal compression to push the elastomeric ring radially outward to contact the casing, thereby isolating a portion of the casing. In accordance with the present invention, expandable barriers are provided on opposing surfaces of the elastomeric ring. Each of the barriers has cooperating sections that are independently bonded to the elastomeric, so that when the elastomeric ring is pushed radially outward, the ring pulls the sections of the expandable barriers to move each section radially outward. The elastomeric ring is thereby constrained between the expandable barriers and the casing. In this way, the integrity of the seal is maintained, even when used in high pressure and / or high temperature wellbore environments. The invention is particularly advantageous for deepwater environments, where temperatures can exceed 180°F (82°C) and / or pressures can exceed 10,000 psid (69,000 kPa).

[0029] The seal of the present invention may be provided in new packer systems or may be used to retrofit an existing packer system.

[0030] In the specification and appended claims, the terms “energize,” “energization,” “energized,” are used to mean “activated with,” activated with via one or more elements.” The term “extrusion,” “extruded,” “extruded by,” are used to mean the process of deforming resilient seals by forcing or pushing it out, especially through a small opening. The term “sealing,” “seal,” “sealed by,” are used to mean setting “one elastomeric element”or “more than one elastomeric element to form a pressure barrier rated for well pressure and well temperature.

[0031] Referring now to Figs. 1A and IB, the seal of the present invention 10 has an elastomeric ring 12, a first expandable barrier 14, and a second expandable barrier 16. The seal 10 is deployed around a packer mandrel 18, which may be a new mandrel or provided in an existing packer retrofitted by the present invention. For ease of discussion, other elements of the packer system in which the seal of the present invention 10 may be deployed are not shown. These elements will be understood by those skilled in the art. The packer is adapted to be deployed in a casing 22 in a wellbore (not shown).

[0032] The elastomeric ring 12 defines a centre hole 24 for receiving the packer mandrel 18. The centre hole 24 has a longitudinal axis 26. The first and second expandable barriers 14, 16 are provided on opposing surfaces of the elastomeric ring 12, the opposing surfaces being perpendicular to the longitudinal axis 26.

[0033] Each of the first and second expandable barriers 14, 16 has cooperating sections 20 that are independently bonded to the elastomeric ring 12. When the elastomeric ring 12 is compressed longitudinally by the packer, the seal 10 expands radially outward to contact the casing 22. Because the cooperating sections 20 of the first and second expandable barriers 14, 16 are independently bonded to the elastomeric ring 12, the sections 20 move radially outward when the elastomeric ring 12 is displaced radially outward. In this way, the present invention 10 constrains the elastomeric ring 12 between the first and second expandable barriers 14, 16 and the casing 22.

[0034] When the packer is no longer needed, compression of the elastomeric ring 12 is released to return the elastomeric ring 12 to its original diameter. As the elastomeric ring 12 retracts radially inwardly, the sections 20 of the first and second expandable barriers 14, 16 are pulled radially inwardly.

[0035] The seal of the present invention 10 represents a significant improvement over conventional packer seals by constraining the elastomeric ring 12 when it softens to a fluid in high-temperature and / or high-pressure environments. Specifically, the cooperating sections of the first and second expandable barriers 14, 16 provide constraints to the natural tendency of a fluid-like elastomeric material from extruding to the casing 22 on either side of the intended seal.

[0036] The elastomeric material is preferably a non-swellable elastomeric material. Examples of non-swellable elastomeric material include, without limitation, synthetic and natural elastomers. Suitable synthetic elastomers include, without limitation, nitrile butadiene rubbers, hydrogenated nitrile butadiene rubbers, fluoroelastomers, perfluoroelastomers, ethylene propylene rubber, tetrafluoro ethylene / propylene copolymer rubbers, neoprene, ethylene acrylic rubber, acrylic ester rubber, ethylene propylene diene rubber, polyepichlorohydrin homopolymer, polyepichlorohydrin-co-ethylene oxide copolymer, polyepichlorohydrin ethylene oxide terpolymer, ethylene / propylene oxide copolymer, chloroprene, styrene rubber, and the like.

[0037] Several embodiments of the first and second expandable barriers 14, 16 are provided herein and will be discussed with reference to the related drawings. The first and second expandable barriers 14, 16 are preferably made of metal. While some expansion and contraction of the material of construction may occur with change in temperature, as used herein, the term expandable in reference to the first and second expandable barriers 14, 16 means an increase in outer diameter of the collective components of the first and second expandable barriers 14, 16.

[0038] In the embodiment of Figs. 1A and IB, the first and second expandable barriers 14, 16 are each formed of sixteen truncated pie sections 20, provided in two layers. Eight truncated pie sections 20 in one layer cooperate to form a circle in the non-expanded (retracted) condition. The two layers of eight pie sections 20 cooperate to block extrusion of the elastomeric seal 12 when it softens under high temperatures and / or high pressures. As shown in the side elevation view of Fig. IB, the placement of the pie sections 20 of the two layers of each of the first and second expandable barrier 14, 16 is radially offset so that the gaps between sections 20 are blocked by the cooperating layer. Specifically, in the embodiment of Figs. 1A and IB, the two layers are radially offset so that each section 20 of a first of the two layers overlaps a gap between a section 20 of the second of the two layers. It will be understood that other sizes and numbers of the pie sections 20 may be selected as needed, for example in view of the diameter of the casing 22 in which the seal of the present invention 10 will be deployed.

[0039] Figs. 2A and 2B show the effect of the present invention 10 when the seal is compressed. Fig. 2A shows that the elastomeric ring 12 has been longitudinallycompressed to push the seal radially outwardly to contact the casing 22. As the elastomeric ring 12 expanded radially outwardly, the sections 20 of the first and second expandable barriers 14, 16 were pulled radially outwardly to block longitudinal flow of the elastomeric ring 12. Fig. 2A shows extrusion of the elastomeric ring 12 between sections 20 of the bottom layer of the first expandable barrier 14. The present invention 10 provides a block to further extrusion by the radial offset of the two layers of the first expandable barrier 14. This is depicted by the extrusion blocked by the sections 20 of the top layer of the first expandable barrier 14.

[0040] The cooperating sections 20 of the first and second expandable barriers 14, 16 are independently bonded to the elastomeric ring 12, for example, without limitation by chemical bonding, vulcanization, or a combination thereof. Preferably, the cooperating sections 20 of the first and second expandable barriers 14, 16 are independently bonded to the elastomeric ring 12 by vulcanization in a manner known to those skilled in the art.

[0041] In the embodiment of Fig. 1A, the bonds are formed at the interface between the elastomeric ring 14 and the portions of each section 20 of the first and second expandable barriers. These independent bonds at each section 20 remain intact while the elastomeric ring 12 expands radially, as depicted in Figs. 2A and 2B.

[0042] In the embodiment of Figs. 1 A and IB, the elastomeric ring 12 is formed of one elastomeric ring. In the embodiment of Figs. 3A - 3C, the elastomeric ring 12 is formed of two elastomeric rings, while in the embodiment of Figs. 7A - 7C, the elastomeric ring 12 is formed of three elastomeric rings. In the case of two or more elastomeric rings, each may independently be formed of a different elastomer, and / or may have the same or different thickness. Some conventional packers have a metal ring disposed between two conventional seal elements. In a retrofit of such a conventional packer, the embodiment of Figs. 1A - 1C, Figs. 3A - 3C or Figs. 7A - 7C may be used to replace each conventional seal element with the metal ring disposed therebetween. Alternatively, the elastomeric ring 12 of the present invention may have a metal ring disposed between two elastomeric rings. In a further alternative, the embodiment of Figs. 1 A - 1C, Figs. 3A - 3C or Figs. 7A - 7C may be sized to replace the conventional seal elements and metal ring in its entirety. It will be understood that the different embodiments of the first and second expandable barriers14, 16 of Figs. 1 A and IB, Figs. 3A-3C, and Figs. 7A-7C may be combined with any of the elastomeric ring 12 embodiments shown in these drawings.

[0043] Like the embodiment of Figs. 1A and IB, the first and second expandable barriers 14, 16 of the embodiment of Figs. 3A - 3C are each formed of sixteen truncated pie sections 20, provided in two layers. Again, it will be understood that other sizes and numbers of the pie sections 20 may be selected as needed, for example in view of the diameter of the casing 22 in which the seal of the present invention 10 will be deployed.

[0044] Each of the truncated pie sections 20 are T-shaped with a vertically depending leg 38 for further anchoring each section 20 in the elastomeric ring 12, as shown more clearly in Figs. 4A and 4B. The vertically depending leg 38 of the sections 20 in the first layer of the first and second expandable barriers 14, 16 passes through a gap between the sections 20 in the second layer of the first and second expandable barriers 14, 16.

[0045] In the embodiment of Figs. 3A-3C, the bonds are formed at the interface between the elastomeric ring 12 and the portions of each section 20 of the first and second expandable barriers 14, 16, including the vertically depending leg 38. An advantage of the embodiment of Figs. 3A-3C, as compared to the embodiment of Figs. 1A and IB, is the increased bonding area between each section 20 and the elastomeric ring 12. A further advantage of the embodiment of Figs. 3A-3C is improved cooperation between layers by maintaining alignment and a uniform gapping with the leg 38 between sections 20 of each layer.

[0046] Figs. 5A and 5B schematically show the cooperation between the T-shaped sections 20 of the Figs. 3A - 3C embodiment before (Fig. 5A) and after (Fig. 5B) the seal is energized. Figs. 6A and 6B illustrate another embodiment of Figs. 3 A - 3C wherein sections 20 of the first layer of expandable barriers 14, 16 have a vertically depending leg 38, while the sections 20 of the second layer of expandable barriers 14, 16 do not have a vertically depending leg 38.

[0047] In the embodiment of Figs. 7A-7C, the first and second expandable barriers 14, 16 are each formed of eight truncated pie sections 20. Again, it will be understood that other sizes and numbers of the pie sections 20 may be selected as needed, for example in view of the diameter of the casing 22 in which the seal of the present invention 10 will be deployed.

[0048] Each of the truncated pie sections 20 are Z-shaped with a vertically depending leg 38 for further anchoring each section 20 in the elastomeric ring 12, as shown more clearly in Figs. 8A and 8B. The Z-shaped sections 20 cooperate by overlapping the top portion of a Z-shape section with the bottom portion of an adjacent Z-shape section.

[0049] In the embodiment of Figs. 7A - 7C, the bonds are formed at the interface between the elastomeric ring 12 and the portions of each section 20 of the first and second expandable barriers 14, 16, including the vertically depending leg 38. An advantage of the embodiment of Figs. 7A - 7C, as compared to the embodiment of Figs. 1A and IB, is the increased bonding area between each section 20 and the elastomeric ring 12. A further advantage of the embodiment of Figs. 7A - 7C is improved cooperation between layers by maintaining alignment with the overlapping Z-sections.

[0050] Figs. 9A-9B schematically show the cooperation between the Z-shaped sections 20 of the Figs. 7A - 7C embodiment before (Fig. 9A) and after (Fig. 9B) the seal is energized. Figs. 10A and 10B illustrate a further embodiment of the sections of the Figs. 7A - 7C embodiment without vertically depending legs 38.

[0051] Figs. 11A and 11B illustrate a further embodiment of the seal of the present invention 10 featuring a tapered seal energization ring 32. The embodiment of Figs. 11A and 1 IB may be used with any of the embodiments of Figs. 1 A and IB, Figs. 3A - 3C, and Figs. 7A - 7C with a modification as will be described below. For simplicity, the vertically depending legs 28 of the embodiments of Figs. 3 A - 3C, and Figs. 7A - 7C is intentionally not shown in the cross-section of Fig. 1 IB.

[0052] The tapered seal energization ring 32 has a radially outward taper on the face of the ring 32 facing the first and second expandable barriers 14, 16. Accordingly, one face of the ring 32 is substantially flat, while the other side of the ring 32 is sloped such that the ring 32 is thicker at the inner circumference thereof.

[0053] For the embodiment of Figs. 11A and 1 IB, the embodiment of Figs. 1A and IB is modified to provide a radial inward taper on the first layer of truncated pie sections 20 of the first and second expandable barriers 14, 16.

[0054] Likewise, for the embodiment of Figs. 11A and 1 IB, the embodiment of Figs. 3A - 3C is modified to provide a radial inward taper on the first layer of truncated pie sections 20 of the first and second expandable barriers 14, 16.

[0055] Meanwhile, for the embodiments of Figs. 1 1 A and 11B, the embodiment of Figs. 7A - 7C is modified to provide a radial inward taper on the upper portion of the Z- shaped sections 20 of the first and second expandable barriers 14, 16.

[0056] As shown in Figs. 11A and 11B, the radial outward taper of the tapered seal energization ring 32 cooperates with the radial inward taper of the first and second expandable barriers 14, 16 as the first and second expandable barriers 14, 16 are moved radially outward and inward with elastomeric ring 12 compression and retraction.

[0057] The first and second expandable barriers 14, 16 are additionally energized in their expansion and sealing of well pressure by the cooperating taper of the tapered energization rings 32. The tapered energization rings 32 will push the expandable barriers 14, 16bonded to elastomeric ring 12 against the casing 22 inner diameter before the elastomeric ring 12 has softened under the setting load to seal wellbore pressure. The embodiment of Figs. 11A and 1 IB further improve the integrity of the seal of the present invention 10.

[0058] Fig. 12 illustrates the deployment of the seal of the present invention 10 in a conventional packer 100. It will be understood that various elements of the conventional packer 100 illustrated in Fig. 12 may be absent, modified or replaced in other known packers. The intent of Fig. 12 is to show the seal of the seal of the present invention in a packer, that may be designed specifically for the seal of the present invention 10 or retrofitted by the seal of the present invention 10.

[0059] Without the seal of the present invention 10, the pressure rating of a conventional packer is rated to a lower pressure and therefore cannot provide the required seal integrity required for high-temperature and / or high-pressure environments due to limitations in the strength of the elastomeric material to seal a gap between the packer outer diameter and the casing inner diameter under well pressure.

[0060] An example of a conventional packer system 100 in which the seal of the present invention 10 may be deployed has a top sub with a rotary shoulder box connection 101, a hold-down slip section 102, a hang-off slip section 106, a packer mandrel 18, a friction section 108, and a bottom sub with rotary shoulder pin connection 109.

[0061] Although a few embodiments of the disclosure have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications arepossible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.

Claims

CLAIMS1. A seal for a packer, the packer adapted to be disposed in a casing in a wellbore, comprising: an elastomeric ring defining a centre hole with a longitudinal axis, the centre hole adapted to receive a mandrel of a packer therethrough, the elastomeric ring having opposing surfaces perpendicular to the longitudinal axis; and a first expandable barrier and a second expandable barrier on opposing surfaces of the elastomeric ring, the opposing surfaces being perpendicular to the longitudinal axis; each of the first expandable barrier and the second expandable barrier having cooperating sections that are independently bonded to the elastomeric ring, so that when the elastomeric ring is compressed longitudinally to expand the seal radially outward, the sections move radially outward, thereby constraining the elastomeric ring between the first expandable barrier, the second expandable barrier, and the casing.

2. The seal according to claim 1, wherein each of the first expandable barrier and the second expandable barrier are formed of two layers of cooperating sections, the two layers radially offset so that each section of a first of the two layers overlaps a gap between sections of the second of the two layers.

3. The seal according to claim 2, wherein a plurality of the sections of the first expandable barrier and the second expandable barrier have a vertically depending leg bonded to the elastomeric ring, wherein each vertically depending leg passes through the gap between sections.

4. The seal according to claim 1, wherein each of the first expandable barrier and the second expandable barrier are formed with cooperating Z-shaped sections.

5. The seal according to claim 1, further comprising a tapered seal energization ring on either side of the seal, wherein the first expandable barrier and the secondexpandable barrier are each provided with cooperating tapers to cooperate with the tapered seal energization ring.

6. The seal according to claim 1, wherein the cooperating sections are bonded to the elastomeric ring by vulcanization.

7. The seal according to claim 1, wherein the elastomeric ring is formed of a non- swellable rubber.

8. The seal according to claim 1, wherein the elastomeric ring is formed by at least two rings.

9. A method for isolating a portion of a wellbore, comprising the steps of: providing a packer having a seal comprising: an elastomeric ring defining a centre hole with a longitudinal axis, the centre hole adapted to receive a mandrel of a packer therethrough, the elastomeric ring having opposing surfaces perpendicular to the longitudinal axis; and a first expandable barrier and a second expandable barrier on opposing surfaces of the elastomeric ring, the opposing surfaces being perpendicular to the longitudinal axis; each of the first expandable barrier and the second expandable barrier having cooperating sections that are independently bonded to the elastomeric ring; deploying the packer in a casing in the wellbore; and energizing the seal by longitudinally compressing the elastomeric ring to expand the seal radially outward to contact the casing, thereby moving the cooperating sections radially outward to constrain the elastomeric ring between the first expandable barrier, the second expandable barrier, and the casing.

10. The method according to claim 1, wherein each of the first expandable barrier and the second expandable barrier are formed of two layers of cooperating sections, the two layers radially offset so that each section of a first of the two layers overlaps a gap between sections of the second of the two layers.11 . The method according to claim 2, wherein a plurality of the sections of the first expandable barrier and the second expandable barrier have a vertically depending leg bonded to the elastomeric ring, wherein each vertically depending leg passes through the gap between sections.

12. The method according to claim 1, wherein each of the first expandable barrier and the second expandable barrier are formed with cooperating Z-shaped sections.

13. The method according to claim 1, further comprising a tapered seal energization ring on either side of the seal, wherein the first expandable barrier and the second expandable barrier are each provided with cooperating tapers to cooperate with the tapered seal energization ring.

14. The method according to claim 1, wherein the cooperating sections are bonded to the elastomeric ring by vulcanization.

15. The method according to claim 1, wherein the elastomeric ring is formed of a non-swellable rubber.

16. The method according to claim 1 , wherein the elastomeric ring is formed by at least two rings.

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