Seal assembly

Abstract

A seal assembly is provided that includes an elastomeric portion; a primary extrusion barrier which reinforces the elastomeric portion; and a secondary extrusion barrier disposed between the elastomeric portion and the primary extrusion barrier to prevent entry of the elastomeric portion into open areas in the primary extrusion barrier.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application Ser. No. 60/715,428, filed on Sep. 9, 2005, which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to a seal assembly, such as a seal assembly for use with a well bore packing tool (commonly referred to as “packer”), and particularly to a seal assembly having an elastomeric material portion, and primary and secondary extrusion barrier portions, which reinforce the elastomeric material portion and increase the life and durability of the seal assembly.

BACKGROUND

Seal assemblies, such as those used on well bore packers are typically cylindrically shaped structures having an inner diameter disposed in surrounding relation to a first device, such as a packer, and an outer diameter that may be forced into sealing engagement with a second device, such as an inner diameter of a casing segment.

For such applications, seal assemblies typically include an elastomeric material portion, which may be deformed to extend radially outwardly to sealingly engage the inner diameter of the casing segment. However, during such a sealing engagement, the elastomeric material has a tendency to extrude, or extend, longitudinally along the inner diameter of the casing segment. Such a movement of the elastomeric material decreases the sealing efficiency of the elastomeric material.

As such, some seal assemblies include an extrusion barrier disposed adjacent to the elastomeric material at the open ended portions of the seal assembly. Such extrusion barriers reinforce the elastomeric material, while preventing (or at least reducing) the extrusion of the elastomeric material longitudinally along the inner diameter of the casing segment, thus improving the sealing efficiency of the elastomeric material.

A problem with such a configuration is that, during deformation, portions of the elastomeric material often extend into expanded areas in the extrusion barrier. For example, in instances where the extrusion barrier is a coil spring, during deformation the elastomeric material tends to extend into the expanded areas between the coils. As such, as the elastomeric material returns to its pre-deformed shape, the extrusion barrier often pulls at or pinches the elastomeric material as the elastomeric material exits the expanded areas in the extrusion barrier. This causes the elastomeric material to wear at an undesirably high rate. This type of wear is commonly associated with, but not limited to, applications which require multiple sets of a packer (i.e. when the seals of a packer are alternately sealed and unsealed multiple times) with the application of multiple high pressure differentials applied across the seal. These cyclic, loading and unloading conditions on the seal promote deterioration of the seal body.

Accordingly, a need exists for a seal assembly having an improved extrusion barrier portion, which increases the life and durability of the seal assembly.

SUMMARY

In one embodiment, the present invention is a seal assembly that includes an elastomeric portion; a primary extrusion barrier which reinforces the elastomeric portion; and a secondary extrusion barrier disposed between the elastomeric portion and the primary extrusion barrier to prevent entry of the elastomeric portion into open areas in the primary extrusion barrier.

In another embodiment, the present invention is a seal assembly that includes an elastomeric portion; a primary extrusion barrier, which is more rigid than the elastomeric portion to reinforce the elastomeric portion; and a secondary extrusion barrier disposed between the elastomeric portion and the primary extrusion barrier, which is more dense than the elastomeric portion to prevent entry of the elastomeric portion into open areas in the primary extrusion barrier.

In yet another embodiment, the present invention is a well bore packer that includes a packer mandrel; and either of the seal assemblies described above disposed in surrounding relation to the packer mandrel.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will be better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

FIG. 1 is side view of an upper portion of a well bore packer having a seal assembly according to one embodiment of the present invention disposed thereon;

FIG. 2 is a longitudinal cross-sectional view of a well bore packer having a seal assembly according to another embodiment of the present invention disposed thereon; and

FIG. 3 is a longitudinal cross-sectional view of a well bore packer having a seal assembly according to yet another embodiment of the present invention disposed thereon.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

As shown in FIGS. 1-3, embodiments of the present invention are directed to a seal assembly. The seal assembly includes an elastomeric material portion, and a primary extrusion barrier for reinforcing the elastomeric material portion. Disposed between the elastomeric material portion and the primary extrusion barrier is a secondary extrusion barrier. The secondary extrusion barrier prevents the elastomeric material portion from extruding, or extending, into the primary extrusion barrier during deformation of the elastomeric material portion. If the elastomeric material portion is allowed to extrude into the primary extrusion barrier, the elastomeric material portion wears at an undesirably high rate. As such, the secondary extrusion barrier increases the life and durability of the seal assembly.

FIG. 1 shows a seal assembly 10 according to one embodiment of the present invention. Although a seal assembly according to the present invention may be used in conjunction with any appropriate device, in the depicted embodiment, the seal assembly is disposed on a well bore packer 12 (note, for clarity purposes, only the upper portion of the packer is shown.)

The packer 12 may be any appropriate packer, such as that described in U.S. Pat. App. No. 60/652,805, entitled “Packer for Spirit Tool”, and related non-provisional filed on Aug. 26, 2005(Atty. Dk. No. 25.0316), the entire contents of which is hereby incorporated by reference. When used in combination with a well bore packer, the seal assembly 10 may be used for multi-layer, perforating, and stimulation applications, or downhole annular barrier applications, among other appropriate applications.

FIG. 2 shows a seal assembly 10′ according to another embodiment of the present invention. As shown, the seal assembly 10′ is a generally cylindrically shaped hollow tube having an inner diameter disposed in surrounding relation to a packer mandrel 14 of a well bore packer 12′.

In the depicted embodiment, the seal assembly 10′ includes an elastomeric material portion 16, a primary extrusion barrier 18, and a secondary extrusion barrier 20. The elastomeric material portion 16 may be composed of any material, such as any one of a variety of well known materials appropriate for creating fluid and/or pressure seals.

Disposed at each longitudinal end of the elastomeric material portion 16 is a primary extrusion barrier 18. The primary extrusion barrier 18 reinforces the elastomeric material portion 16 to provide added structural and stability to the seal assembly 10′. As such, in one embodiment the primary extrusion barrier 18 is composed of a material which is stronger or more rigid than the elastomeric material portion 16. For example, exemplary primary extrusion barrier 18 materials include coil springs, c-rings, wave springs and/or any combination thereof, among other appropriate materials. Disposed between the elastomeric material portion 16 and the primary extrusion barrier 18 is the secondary extrusion barrier 20, the utility of which is described in detail below.

In one embodiment, the seal assembly 10′ is deformed by a mechanical, hydraulic, or electrically generated force applied at the ends of the seal assembly 10′. As the seal assembly 10′ is compressed in this manner, the elastomeric material portion 16 is constricted on its ends and forced to expand in a radial direction until it comes into contact with and sealingly engages a target seal area, such as the inner diameter of a casing segment (not shown.)

During this compression, the primary extrusion barrier 18 is also forced in the radial direction into contact with the casing segment. The primary extrusion barrier 18, thus positioned, prevents the elastomeric material portion 16 from extruding or extending therepast in a longitudinal direction along the inner diameter of the casing segment. The primary extrusion barrier 18 thus improves the sealing efficiency of the elastomeric material portion 16 with the inner diameter of the casing segment.

However, as described above, the radial movement of the primary extrusion barrier 18 may create openings or expanded areas into which the elastomeric material portion 16 may extend when compressed, which if allowed to occur would cause the elastomeric material portion 16 to wear at an undesirably high rate. To alleviate this problem, the secondary extrusion barrier 20 is disposed between the elastomeric material portion 16 and the primary extrusion barrier 18. As with the primary extrusion barrier 18, during the compression of the seal assembly 10′, the secondary extrusion barrier 20 is also forced in the radial direction into contact with the casing segment.

Thus positioned, the secondary extrusion barrier 20 acts as a flow barrier, which resists the flow of the heated or pressurized elastomeric material portion 16 into the primary extrusion barrier 18. As a result, the secondary extrusion barrier 20 increases the life and durability of the seal assembly 10′ by eliminating the extrusion of the elastomeric material portion 16 into any expanded or open areas in the primary extrusion barrier 18.

In order to prevent the flow of the elastomeric material portion 16 into the expanded or open areas in the primary extrusion barrier 18, in one embodiment the secondary extrusion barrier 20 is composed of a material which is more dense than the elastomeric material portion 16. For example, exemplary secondary extrusion barrier 20 materials include wire, Aramid fiber, carbon fiber, foam, or plastic, and/or any combination thereof, arranged in a mesh, wrapped, woven, or solid configuration.

Alternatively, the secondary extrusion barrier 20 may be composed of any other material, arranged in any other configuration, which is suitable for preventing the extrusion of the elastomeric material portion 16 into the primary extrusion barrier 18 during compression of the seal assembly 10′. Exemplary materials for the elastomeric material portion 16 include a Hydrogenated Nitrile (HNBR) elastomeric compound, a Nitrile (NBR) compound, or an Aflas compound, among other materials capable of forming an appropriate seal.

In one embodiment, the elastomeric material portion 16 is composed of a Hydrogenated Nitrile (HNBR) elastomeric compound, the primary extrusion barrier 18 is composed of a looped coil spring, and the secondary extrusion barrier 20 is composed of a woven wire mesh fabric.

In one embodiment, the secondary extrusion barrier 20 is formed around the primary extrusion barrier 18 and the combination of the primary and secondary extrusion barriers 18 and 20 is attached to the elastomeric material portion 16 in a compression molding process. In an alternative embodiment, the extrusion barriers 18 and 20 may be placed in series with the elastomeric material portion 16 rather than being molded thereto.

The geometry of the secondary extrusion barrier 20 is not limited to that shown in FIG. 2. Also, in one embodiment the secondary extrusion barrier 20 completely encloses the primary extrusion barrier 18. However, it is only necessary that the secondary extrusion barrier 20 forms a barrier between the elastomeric material portion 16 and the primary extrusion barrier 18. Thus, although possible, is it not necessary for the secondary extrusion barrier 20 to completely enclose the primary extrusion barrier 18.

The seal assembly may be a one piece seal (as is shown in FIG. 2) or a multiple section seal (is shown in FIGS. 1 and 3). FIG. 3 shows a multiple section seal. However, the descriptions and variations described above with respect to FIG. 2 apply to FIG. 3. As such, in order to avoid duplicity, only the differences between FIGS. 2 and 3 are discussed herein. For instance, the seal assembly 10″ of FIG. 3 includes a first elastomeric material portion 16″, and a second elastomeric material portion 22, disposed between the first elastomeric material portion 16″ and the secondary extrusion barrier 20. In one embodiment the second elastomeric material portion 22 is composed of a harder material than the first elastomeric material portion 16″.

Exemplary materials for the elastomeric material portions 16″ and 22 include a Hydrogenated Nitrile (HNBR) elastomeric compound, a Nitrile (NBR) compound, or an Aflas compound, among other materials capable of forming an appropriate seal.

In one embodiment the first elastomeric material portion 16″ is composed of a Hydrogenated Nitrile (HNBR) elastomeric compound, and the second elastomeric material portion 22 is also composed of a Hydrogenated Nitrile (HNBR) elastomeric compound, but one having a greater hardness than that of the first elastomeric material portion 16″.

Although FIGS. 2 and 3 each show extrusion barriers at each longitudinal end of the seal assembly, one skilled in the art will appreciate that it is only necessary for one longitudinal end of the seal assembly to include the extrusion barriers. Also, although the above description focuses on the seal assembly 10′ being used in combination with a well bore packer to form a seal with the inner diameter of a casing segment, one skilled in the art will appreciate that a seal assembly according to the present invention may be used on any appropriate device to form any appropriate seal.

It is to be noted that each of the seal assemblies described above maintains structural integrity over multiple sets and differential pressure applications, without excessive deterioration of the elastomeric portion(s) of the seal assemblies.

The preceding description has been presented with reference to presently preferred embodiments of the invention. Persons skilled in the art and technology to which this invention pertains will appreciate that alterations and changes in the described structures and methods of operation can be practiced without meaningfully departing from the principle, spirit and scope of this invention. Accordingly, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.

Claims

1. A seal assembly comprising:

an elastomeric portion;

a primary extrusion barrier which reinforces the elastomeric portion; and

a secondary extrusion barrier disposed between the elastomeric portion and the primary extrusion barrier to prevent entry of the elastomeric portion into open areas in the primary extrusion barrier.

2. The seal assembly of claim 1, wherein the primary extrusion barrier is more rigid than the elastomeric portion.

3. The seal assembly of claim 2, wherein the primary extrusion barrier comprises a material chosen from the group consisting of coil springs, c-rings, and wave springs.

4. The seal assembly of claim 1, wherein the secondary extrusion barrier is more dense than the elastomeric portion.

5. The seal assembly of claim 4, wherein the secondary extrusion barrier comprises a material chosen from the group consisting of wire, Aramid fiber, carbon fiber, foam, and plastic.

6. The seal assembly of claim 5, wherein the secondary extrusion barrier material comprises a configuration chosen from the group consisting of mesh, wrapped, woven, and solid.

7. The seal assembly of claim 1, wherein the primary extrusion barrier comprises a coil spring, and the secondary extrusion barrier comprises a woven wire mesh fabric.

8. The seal assembly of claim 7, wherein the elastomeric portion comprises a material chosen from the group consisting of a Hydrogenated Nitrile compound, a Nitrile compound, and an Aflas compound.

9. The seal assembly of claim 1, wherein the elastomeric portion is a first elastomeric portion, and wherein the seal assembly further comprises a second elastomeric portion, which is adjacent to the first elastomeric portion.

10. A seal assembly comprising:

an elastomeric portion;

a primary extrusion barrier, which is more rigid than the elastomeric portion to reinforce the elastomeric portion; and

a secondary extrusion barrier disposed between the elastomeric portion and the primary extrusion barrier, which is more dense than the elastomeric portion to prevent entry of the elastomeric portion into open areas in the primary extrusion barrier.

11. The seal assembly of claim 10, wherein the secondary extrusion barrier comprises a material chosen from the group consisting of wire, Aramid fiber, carbon fiber, foam, and plastic.

12. The seal assembly of claim 11, wherein the secondary extrusion barrier material comprises a configuration chosen from the group consisting of mesh, wrapped, woven, and solid.

13. The seal assembly of claim 11, wherein the primary extrusion barrier comprises a material chosen from the group consisting of coil springs, c-rings, and wave springs.

14. The seal assembly of claim 10, wherein the primary extrusion barrier comprises a coil spring, and the secondary extrusion barrier comprises a woven wire mesh fabric.

15. The seal assembly of claim 14, wherein the elastomeric portion comprises a material chosen from the group consisting of a Hydrogenated Nitrile compound, a Nitrile compound, and an Aflas compound.

16. The seal assembly of claim 10, wherein the elastomeric portion is a first elastomeric portion, and wherein the seal assembly further comprises a second elastomeric portion, which is adjacent to the first elastomeric portion.

17. A well bore packer comprising:

a packer mandrel; and

a seal assembly disposed in surrounding relation to the packer mandrel, wherein the seal assembly comprises: an elastomeric portion, a primary extrusion barrier, which is more rigid than the elastomeric portion to reinforce the elastomeric portion, and a secondary extrusion barrier disposed between the elastomeric portion and the primary extrusion barrier, which is more dense than the elastomeric portion to prevent entry of the elastomeric portion into open areas in the primary extrusion barrier.

18. The seal assembly of claim 17, wherein the secondary extrusion barrier comprises a material chosen from the group consisting of wire, Aramid fiber, carbon fiber, foam, and plastic.

19. The seal assembly of claim 18, wherein the secondary extrusion barrier material comprises a configuration chosen from the group consisting of mesh, wrapped, woven, and solid.

20. The seal assembly of claim 18, wherein the primary extrusion barrier comprises a material chosen from the group consisting of coil springs, c-rings, and wave springs.

21. The seal assembly of claim 17, wherein the primary extrusion barrier comprises a coil spring, and the secondary extrusion barrier comprises a woven wire mesh fabric.

22. The seal assembly of claim 21, wherein the elastomeric portion comprises a material chosen from the group consisting of a Hydrogenated Nitrile compound, a Nitrile compound, and an Aflas compound.

23. The seal assembly of claim 17, wherein the elastomeric portion is a first elastomeric portion, and wherein the seal assembly further comprises a second elastomeric portion, which is adjacent to the first elastomeric portion.