LOAD DELAYED SEAL ELEMENT, SYSTEM, AND METHOD

Abstract

A seal assembly including, a deformable force transmission portion having an inner surface and an outer surface, the force transmission portion operative to transmit an applied force to a component linked to the seal assembly, and deformable in a direction transverse to a main axis of the seal assembly in response to a increased applied force greater than a threshold setting force, and a flexible outer seal portion attached to the outer surface and method.

Description

BACKGROUND

Flow control seals are well known in downhole industries such as drilling and completion industries and especially so in the hydrocarbon recovery industry. Those of skill in the art will readily recognize that all manner of seals are used including compression seals, inflatable seals, etc. for different applications in the downhole environment.

Compression set seals are traditionally fabricated from flexible rubber material. The seals are set by an axial force that may be applied mechanically by, for example, decreasing the weight of a tubing string supported by equipment uphole such as a derrick. Applying an axial force to the seal expands the seal such that the seal contacts the walls of a borehole. And while compression set seals are some of the oldest seals, and indeed some of the most reliable seals, the art is always receptive to improvements in performance.

SUMMARY

A seal assembly including, a deformable force transmission portion having an inner surface and an outer surface, the force transmission portion operative to transmit an applied force to a component linked to the seal assembly, and deformable in a direction transverse to a main axis of the seal assembly in response to a increased applied force greater than a threshold setting force, and a flexible outer seal portion attached to the outer surface.

A method for sealing a borehole includes applying a first axial force to a seal system operative to actuate a first seal assembly, applying a second axial force greater than the first axial force operative to actuate a second seal assembly.

A seal assembly system includes a first seal assembly and a second seal assembly each having a deformable force transmission portion having an inner surface and an outer surface, the force transmission portion operative to transmit an applied force to a component linked to the seal assembly, and deformable in a direction transverse to a main axis of the seal assembly in response to a increased applied force greater than a threshold setting force, and a flexible outer seal portion attached to the outer surface.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings wherein like elements are numbered alike in the several figures:

FIG. 1 is a perspective partially cut away view of an exemplary embodiment of a seal assembly;

FIG. 2 is a perspective view of an exemplary embodiment of the force transmission portion of the seal assembly of FIG. 1;

FIG. 3 is a side cut-away view of the assembly of FIG. 1;

FIGS. 4A-4C illustrate an exemplary method for setting seals;

FIG. 5 is a perspective view of an alternate embodiment of a seal assembly; and

FIG. 6 is an alternate embodiment of a force transmission portion.

DETAILED DESCRIPTION

FIG. 1 illustrates a perspective partially cut away view of an exemplary embodiment of a seal assembly 10. The assembly 10 includes a deformable force transmission portion 12, which may be tubular in geometry. An outer seal portion 14 is positioned adjacent to, and in one embodiment sealed to, an outer diameter surface of the force transmission portion 12. An inner seal portion 16 is positioned adjacent to, and in one embodiment sealed to, an inner diameter surface of the force transmission portion. The outer seal portion 14 and the inner seal portion 16 may be formed from a flexible material such as, for example, rubber. The force transmission portion 12 may be formed from metal, plastic, or a composite material. The force transmission portion 12 functions to resist a compressive load being applied to the seal 10 so that the same load may be transmitted thorough the seal 10 in order to be used downhole thereof. In one iteration, the use to be made of the force downhole of the seal 10 is as an actuation force. As noted above, compressive forces from uphole of a compressively set seal are traditionally not available downhole of the seal since those forces are reacted out by the radial expansion of the seal into contact with parametrical walls of the annulus in which they are positioned. Once the compression set seal is compressed into sealing contact, much if not all of the compressive load from uphole thereof can be borne by the compression set seal and hence does not transmit therethrough. Because of the configuration taught herein including the force transmission portion 12, compressive setting force can indeed be used downhole of the seal 10. This is effected by delaying the setting of the seal 10.

The seal assembly 10 is capable of transmitting a compressive axial force through the force transmission portion 12, and due thereto, to components downhole of seal assembly 10. This occurs while a threshold compressive force is not achieved whereat the seal 10 will itself set. Therefore depending upon the selected threshold force dictated by the ability of the force transmission portion to hold a load without itself deforming, other tools including seals, slips, or any other mechanically activated device downhole may be set (at lower threshold loads than the seal 10) prior to seal 10 setting and effectively preventing the application of compressive force downhole thereof thereafter. It is to be understood that multiple seals 10 may be used in a single system with increasing threshold compression set levels toward a surface location and setting of all of these is effectible through the compression set concept noted herein.

After more downhole components are set, the seal assembly 10 may be set by applying a compressive axial force of greater than the threshold force to the seal assembly 10 that is sufficient to deform the force transmission portion 12. At this point the seal 10 will set substantially normally. It is noted that a byproduct of the teaching hereof may be that the seal 10 is energized to a greater degree than traditional compression set seals because of the embedded force transmission portion that will tend to want to stay deformed once deformation thereof is effected. This is because it is contemplated that the deformation of the portion 12 is plastic deformation somewhere beyond the yield point of the material employed.

While it is to be appreciated that a number of different shaped of force transmission portions 12 could be used, as illustrated, the profile of the force transmission portion 12 has a greater outer diameter in the center of the force transmission portion 12 relative to the ends. This encourages a more uniform deformation of the portion 12 thereby avoiding seal contact pressure irregularities. Other embodiments may include a force transmission portion 12 having a greater outer diameter that is offset from the center resulting in an asymmetrical profile.

Referring to FIG. 2, a perspective view of an exemplary embodiment of the force transmission portion 12 alone, without the balance of the seal assembly 10 provides a greater understanding of the configuration and therefore working of the portion 12. In the illustrated embodiment, circumferential lines 11 and 13 indicate areas of higher bending stress where the portion 12 will tend to yield under compressive load at the selected threshold level.

FIG. 3 illustrates a side cut-away view of the seal assembly 10. The force transmission portion 12 has an outer diameter at the center of the force transmission portion 12 that is greater than the outer diameter of the ends of the force transmission portion 12. The main axis of the assembly 10 is represented by line 38.

FIGS. 4A-4C illustrate an example of the operation of an array of seal assemblies 10 in an arrangement 400. Referring to FIG. 4A, a force 4 is transmitted through the tubing string 2 through the seal assemblies 10a and 10b such that the force 4 actuates a downhole tool 6 (which could be another compression set seal or some other tool responsive to compressive load). The axial force 4 may be applied mechanically by, for example, decreasing support of the weight of a tubing string 2 by, for example, a derrick at the surface (not shown). Referring to FIG. 4B, once the tool 6 is set, the force 4 is increased such that the force is greater than the threshold setting force of the seal assembly 10b (but less than the threshold setting force for the seal assembly 10a); setting the seal assembly 10b. Referring to FIG. 4C, once the seal assembly 10b is set, the force 4 is increased above the threshold setting force for the seal assembly 10a, resulting in the setting of the seal assembly 10a.

FIG. 5 illustrates a perspective view of an alternate embodiment of a seal assembly 50 having a force transmission portion 52, an outer seal portion 54, and an inner seal portion 56. The seal assembly 50 is similar to the seal assemblies described above, however, a force transmission portion 52 includes threaded ends 60 that may be used to connect or link the assembly 50 to downhole and uphole equipment. This configuration would allow transmission of a tensile force through the seal. Where this force could be used to activate devices either before or after the elements were set.

FIG. 6 illustrates another alternate embodiment of a force transmission portion 70. The force transmission portion 70 comprises a plurality of ribs 72 arranged radially about the rotational axis of a seal assembly. The force transmission portion 70 operates similarly to the force transmission portions described above.

While one or more embodiments have been shown and described, modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.

Claims

1. A seal assembly comprising:

a deformable force transmission portion having an inner surface and an outer surface, the force transmission portion operative to transmit an applied force to a component linked to the seal assembly, and deformable in response to a increased applied axial compression force greater than a threshold setting force; and

a flexible outer seal portion attached to the outer surface.

2. The seal assembly of claim 1, wherein the assembly further comprises a flexible inner seal portion attached to the inner surface.

3. The seal assembly of claim 1, wherein the force transmission portion has a center portion having a greater outer diameter than an outer diameter of an end portion.

4. The seal assembly of claim 1, wherein the deformable force transmission portion has a deformable zone defined by a first circumferential line and a second circumferential line spaced along the main axis of the force transmission portion.

5. The seal assembly of claim 4, wherein the deformable force transmission portion has a third circumferential line disposed between the first and second circumferential lines having a diameter greater than the diameter of the first and second circumferential lines.

6. The seal assembly of claim 1, wherein the force transmission portion is metallic.

7. The seal assembly of claim 1, wherein the flexible outer seal portion is a rubber product.

8. The seal assembly of claim 1, wherein the force transmission portion has at least one end having a threaded portion.

9. The seal assembly of claim 1, wherein the applied force is an axial force.

10. The seal assembly of claim 1, wherein the force transmission portion is tubular.

11. The seal assembly of claim 1, wherein the force transmission portion is a plurality of ribs disposed radially about the main axis of seal assembly.

12. A method for sealing a borehole comprising:

applying a first axial force to a seal system operative to actuate a first seal assembly; and

applying a second axial force greater than the first axial force operative to actuate a second seal assembly.

13. The method of claim 12, wherein the first seal assembly is disposed downhole in the borehole relative to the second seal assembly.

14. The method of claim 12, wherein the first axial force is greater than a first threshold force level associated with the first seal assembly and less than a second threshold force level associated with the second seal assembly.

15. The method of claim 12, wherein the method further comprises applying a third axial force to the seal system prior to applying the first axial force to actuate a tool connected to the first seal assembly.

16. A seal assembly system comprising:

a first seal assembly and a second seal assembly each having a deformable force transmission portion having an inner surface and an outer surface, the force transmission portion operative to transmit an applied force to a component linked to the seal assembly, and deformable in a direction transverse to a main axis of the seal assembly in response to a increased applied force greater than a threshold setting force, and a flexible outer seal portion attached to the outer surface.

17. The system of claim 16, wherein the threshold setting force of the first seal assembly is greater than the threshold setting force of the second seal assembly.

18. The system of claim 17, wherein the first seal assembly is disposed uphole of the second seal assembly.

19. The system of claim 16, wherein the threshold setting force of the first seal assembly equals the threshold setting force of the second seal assembly.