US20160245038A1

US20160245038A1 - Swellable Seal with Backup

Info

Publication number: US20160245038A1
Application number: US15/027,516
Authority: US
Inventors: Matthew Bradley Stokes
Original assignee: Halliburton Energy Services Inc
Current assignee: Halliburton Energy Services Inc
Priority date: 2013-11-06
Filing date: 2013-11-06
Publication date: 2016-08-25
Also published as: MX2016004222A; AU2013405012A1; CN105683492A; CA2926387A1; EP3042033A4; RU2631454C1; AU2013405012B2; WO2015069242A1; EP3042033A1; SG11201602567VA; CA2926387C; AR099284A1

Abstract

A well seal assembly for use in a seal groove of a well component. The seal assembly including a swellable elastomer seal to reside in the seal groove. The swellable elastomer seal responsive to expand when in contact with a specified fluid. A backup member is provided to reside in the seal groove, axially between the swellable elastomer seal and an axial end wall of the seal groove. The backup ring includes an undulation that, when axially compressed, expands the backup member.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Phase Application under 35 U.S.C. §371 and claims the benefit of priority to International Application Serial No. PCT/US2013/068776, filed on Nov. 6, 2013, the contents of which are hereby incorporated by reference.

BACKGROUND

The present disclosure relates to well tools that utilize swellable seals.
Downhole conditions in a well present numerous sealing challenges. For example, seals in a well must often withstand extended exposure to high pressures and temperature. In such conditions, commonly used elastomer seals tend to extrude into the gap between the component carrying the seal and the surface sealed against, and ultimately fail. Complex backup ring designs have been developed to address this problem, by bridging the gap and supporting the extrusion against extrusion. However, the backup ring designs are actuated only when the seals are pressurized. Also, in the context of a stinger or stab, where one well component is sealed in a bore of another well component, multiple seals and thus multiple backup rings are used. To accommodate the multiple seals in a small space, O-rings or chevron seals are used. However, the effectiveness of such seals is dependent to the cleanliness and surface finish of the surface sealed against.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic side view of a well incorporating a tubing string.

FIG. 2 is an side cross-sectional view of an example of two well components incoporporating a sealing assembly.

FIGS. 3A and 3B are detail views of the example well components, showing an end of the sealing assembly prior to the seal swelling and after the seal has swelled.

FIG. 4 is a perspective view of an example backup member showing the undulations.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Referring first to FIG. 1, a well includes a substantially cylindrical wellbore 10 that extends from a wellhead 22 at the surface 12 downward into the Earth into one or more subterranean zones of interest 14 (one shown). The subterranean zone 14 can corresponding to a single formation, a portion of a formation, or more than one formulation accessed by the well, and a given well can access one or more than one subterranean zone 14. In certain instances, the formations of the subterranean zone are hydrocarbon bearing, such as oil and/or gas deposits, and the well will be used in producing the hydrocarbons and/or used in aiding production of the hydrocarbons from another well (e.g., as an injection or observation well). The concepts herein, however, are applicable to virtually any type of well. A portion of the wellbore 10 extending from the wellhead 22 to the subterranean zone 14 is lined with lengths of tubing, called casing 16.
The depicted well is a vertical well, extending substantially vertically from the surface 12 to the subterranean zone 14. The concepts herein, however, are applicable to many other different configurations of wells, including horizontal, slanted or otherwise deviated wells, and multilateral wells.
A tubing string 18 is shown as having been lowered from the surface 12 into the wellbore 10. The tubing string 18 is a series of jointed lengths of tubing coupled together end-to-end and/or a continuous (i.e., not jointed) coiled tubing, and includes one or more well tools (e.g., one shown, well tool 20). The string 18 has an interior, center bore that enables communication of fluid between the wellhead 22 and locations downhole (e.g., the subterranean zone 14 and/or other locations). In other instances, the string 18 can be arranged such that it does not extend from the surface 12, but rather depends into the well on a wire, such as a slickline, wireline, e-line and/or other wire.
The concepts herein apply to a sealing arrangement that can be used in a number of different contexts to seal between well components in a well. For example, the sealing arrangement can be used in the well tool 20. In certain instances, the well tool 20 is of a type having an inner tubing component nested in an outer tubing component, with the sealing arrangement described herein configured to seal between the tubings. The sealing arrangement, however, need not be limited to sealing components of the same tool or device. For example, in certain instances, the well tool 20 is a packer type tool (e.g., packer, bridge plug, frac plug and/or other) that has the sealing arrangement configured to seal the tool 20 to the inner surface of the casing 16, a liner or other component in the well to seal the annulus around the tubing string 18. In another example, the tubing string 18 can be placed in the well in two parts, with an uphole component that has a stab or stinger that is received into a corresponding bore of the downhole component. In this instance, the sealing arrangement is configured to seal to the bore of the other component, and thus seal between the two tubings. In yet another example, a running tool or actuating tool can be used to operate the well tool 20 or another component in the well. In this instances, the running or actuating tool has a stinger or stab that is received into a corresponding bore of the tool or device being actuated, and the sealing arrangement is configured to seal between the stinger/stab and bore. Other examples exist and are within the concepts herein.
Referring to FIG. 2, two well components 30, 32 are shown in a half side cross-sectional view. In the present example, the well components 30, 32 are two elongate tubings (e.g., tubings of a well tool, a packer and casing, a stinger and bore, or other), concentrically nested within each other. The inner tubing (component 32) includes a seal groove 24 sized to receive an elongate swellable elastomer seal 26 and backup members 28. Each of the seal groove 24, swellable seal 26 and backup members 28 are annular or ring shaped to encircle the tubular well components 30, 32. An annular gap 34 is formed between the well components 30, 32. Although described herein in connection with tubular well components, the same concepts could be applied to non-cylindrical, flat or other shapes. Thus, the seal 26, backup members 28 and other aspects need not be annular.
The elongate swellable elastomer seal 26 is made from a swellable elastomer that swells or expands on contact with a specified fluid, e.g., oil, water, and/or other. Notably, the swellable elastomer swells in all directions uniformly, unless constrained. Therefore, in the example with the annular swellable elastomer seal 26 in the seal groove 24, the seal 26 swells radially outward, as well as axially within the groove 24, parallel to centerline of the well components 30, 32. The seal 26 is elongate in that it axial dimension is longer than its radial dimension, but other configurations of seal 26 could be provided. In certain instances, the radial dimension of the seal 26 is selected to provide a gap with the component 30 to allow the seal 26 (and component 32) to be inserted and withdrawn from component 30.
A backup member 28 is provided at each end of the seal 26, axially between the seal 26 and opposing axial ends of the seal groove 24. In other instances, only one backup member 28 is provided. The backup member 28 is a wave backup member made as a wave spring, or configured similarly to a wave spring, with one or more axial undulations 36 distributed around the backup member 28. In certain instances, the undulations can be distributed evenly around the backup member 28, for example, as in FIG. 4 showing four undulations 36 distributed at 90° from each other. Although shown as smooth, curving sine wave like undulations 36, the undulations could be more abrupt and/or a different shape. The backup member 28 is constructed of a thin, flat material with parallel sidewall surfaces, and the undulations 36 are configured so that when the member 28 is axially compressed toward flat, they expand the backup member 28 circumferentially, and correspondingly radially outward. In certain instances, the backup member 28 can be sized to lightly contact or provide a gap with the component 30 in an unexpanded (not axially compressed) free state. Such a configuration allows the backup member 28 to slide axially through the component 30 without much or any resistance, allowing the component 32 to be inserted and withdrawn into the component 30. The number and amplitude A of the undulations 36 can be selected so that when the backup member 28 is compressed, it bridges the gap 34 and abuts and presses on the component 30. The number of undulations 36 and the amplitude A of the undulations can be selected to provide a contact pressure against the component 30 to provide an adequate degree of backup that prevents the swellable seal 26 from extruding through gap 34. In certain instances, the backup member 28 is provided with a chamfer 38 on its inner diameter oriented toward the seal 26 to facilitate the member 28 expanding and centering on the seal 26.
The backup member 28 can be constructed of a number of different materials. In certain instances, the member 28 can be constructed of a material having a higher hardness and/or yield strength than the elastomer of the swellable seal 26 to facilitate the backup member 28 providing an effective backup. In certain instances, the material is selected based on its ability to survive the high, downhole temperatures. Some example materials for the backup member include metal, polymer, composite and/or other materials or mixes of materials.
In operation, with the components 30, 32 residing in the well and the backup members 28 and seal 26 residing in the seal groove 24, the swellable seal 26 is contacted with the specified fluid. The seal 26 responds by swelling into contact and sealing to the component 30. In certain instances, the seal formed by the seal 26 is gas tight. FIG. 3A is a detail view about the axial end of the seal groove 24, showing the swellable elastomer seal 26 prior to swelling and the backup 28 unexpanded. When the swellable elastomer seal 26 is in contact with the specified fluid, it swells and expands both radially and axially. In axially expanding, the swellable elastomer seal 26 compresses the backup members 28 against the axial end wall of the seal groove 24. The undulations of the backup members 28 axially compress, and cause the backup members 28 to expand radially into abutting contact with the component 30, as shown in FIG. 3B. Then, as the seal 26 begins to hold a pressure differential, the seal 26 is supported against extrusion through the gap 34 by the low pressure side backup member 28 pressing against the component 30. By providing two backup members 28, the pressure differential can be reversed and the opposing backup member 28 will support the seal 26 against extrusion through the gap 34.
Notably, by using a swellable elastomer seal 26, the surface finish of the surface sealed against on the component 30 need not be tightly controlled, as the swellable seal 26 provides a contact pressure that facilitates sealing rougher surfaces than non-swelling seals. In the context of a stinger or stab, the component 30 need not be provided with a polished bore receptacle. Also, the seal 26 can provie more surface area for sealing than a conventional O-ring or chevron seal. In certain instances, the greater surface area and/or the contact pressure from swelling will allow the swellable seal 26 to seal, even if damaged. Because the seal 26 swells in contact with fluid, a pressure differential is not necessary to achieve a seal or to actuate the backup members 28 into supporting the seal 26. The swelling also facilitates insertion of the component 32 into component 30, because the seal 26 need not contact component 30 until in contact with the specified fluid. Once sealing, the seal 26 resists withdrawal of the component 32 from component 30. In certain instances, because of the simplicity of the backup members 28, the cost to manufacture can be less than other more complex backups and chevron seals.
A number of embodiments have been described. Nevertheless, it will be understood that various modifications may be made. Accordingly, other embodiments are within the scope of the following claims.

Claims

What is claimed is:

1. A well seal assembly for use in a seal groove of an elongate well component, comprising:

a swellable elastomer seal to reside in the seal groove, the swellable elastomer seal responsive to expand when in contact with a specified fluid; and

a backup member to reside in the seal groove axially between the swellable elastomer seal and an axial end wall of the seal groove, the backup member comprising an undulation that, when axially compressed, expands the backup member.

2. The well seal assembly of claim 1, where the backup member comprises a plurality of axial undulations distributed evenly around the backup member.

3. The well seal assembly of claim 1, where the backup member comprises a wave spring.

4. The well seal assembly of claim 1, where the swellable elastomer seal swells axially when in contact with the specified fluid and axially compresses the backup member.

5. The well seal assembly of claim 1, where the well component comprises a first tubular and the seal groove is annular to encircle the first tubular, and the first tubular of the well component is insertable into a specified second tubular; and

where the swellable elastomer seal is annular to encircle the first tubular and swellable to abut and seal against the second tubular.

6. The well seal assembly of claim 5, where the backup member is annular to encircle the first tubular and expands radially, when axially compressed, to press against the second tubular.

7. The well seal assembly of claim 1, comprising a second backup member to reside in the seal groove axially between the swellable elastomer seal and an opposite axial end wall of the seal groove.

8. The well seal assembly of claim 1, where the backup member comprises a chamfer oriented toward the swellable elastomer seal.

9. The well seal assembly of claim 8, where the backup member comprises parallel, opposing axial sidewalls.

10. The well seal assembly of claim 1, where the backup member is a different, harder material than the swellable elastomer seal.

11. A method, comprising:

expanding, in response to contact with a specified fluid, a swellable elastomer seal in a seal groove of an elongate well component; and

axially compressing an undulation of a backup member in the seal groove with the swellable elastomer seal, expanding the backup member outward.

12. The method of claim 11, where axially compressing an undulation of the backup member comprises axially compressing a plurality of axial undulations of the backup member, the undulations distributed evenly around the backup member.

13. The method of claim 11, where axially compressing an undulation of the backup member comprises axially compressing the undulation between the seal and an axial end wall of the seal groove.

14. The method of claim 11, comprising sealing, with the swellable elastomer seal, against a surface of a second well component; and

supporting the swellable elastomer seal against extruding through a gap between the first mentioned well component and the second well component with the backup member.

15. The method of claim 11, comprising axially compressing an undulation of a second backup member in the seal groove with the swellable elastomer seal, expanding the second backup member outward.

16. The method of claim 15, comprising sealing, with the swellable elastomer seal, against a surface of a second well component; and

supporting the swellable elastomer seal against extruding through gaps between the first mentioned well component and the second well component with the first mentioned backup member and the second backup member.

17. A well device for use in a well, comprising:

a swellable seal in a seal groove of the well device, the swellable seal responsive to swell when in contact with a fluid; and

a wave backup ring in the seal groove responsive to expand outward when axially compressed by the swellable seal.

18. The well device of claim 17, where the wave backup ring comprises a plurality of axial undulations distributed evenly around the ring.

19. The well device of claim 17, where the wave backup ring comprises a chamfer oriented toward the swellable seal.

20. The well device of claim 17, comprising a second wave backup ring in the seal groove opposite the swellable seal and responsive to expand outward when axially compressed by the swellable seal.