Title:
DOWNHOLE SEAL
Kind Code:
A1


Abstract:
A downhole seal comprises a seal body having a swellable material configured to swell upon exposure to a swelling activator to establish a seal within a wellbore, and at least one protection element configured to protect at least a portion of the seal body when the downhole seal is translated within a wellbore. The protection element defines a reaming element configured to ream a portion of the wellbore while the downhole seal is translated therethrough.



Inventors:
Carter, Neale (Altens, GB)
Application Number:
12/763022
Publication Date:
10/21/2010
Filing Date:
04/19/2010
Assignee:
Swellfix B.V. (Rijswijk, NL)
Primary Class:
Other Classes:
175/344, 166/195
International Classes:
E21B33/12; E21B10/30
View Patent Images:
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Primary Examiner:
RO, YONG-SUK
Attorney, Agent or Firm:
FULWIDER PATTON LLP (Long Beach, CA, US)
Claims:
We claim:

1. A downhole seal comprising: a seal body comprising a swellable material configured to swell upon exposure to a swelling activator to establish a seal within a wellbore; and at least one reaming element configured to ream an internal surface of a wellbore.

2. The downhole seal according to claim 1, wherein at least one reaming element is configured to ream an internal surface of a wellbore while the downhole seal is being translated therein.

3. The downhole seal according to claim 1, wherein at least one reaming element is configured to ream a wall surface of at least one of a drilled bore and an internal wall surface of a tubing string.

4. The downhole seal according to claim 1, wherein at least one reaming element defines an outer dimension which is greater than an outer dimension of the seal body when in an unswollen configuration.

5. The downhole seal according to claim 1, wherein at least one reaming element defines an outer dimension which is equal to or less than an outer dimension of the seal body when in a swollen configuration.

6. The downhole seal according to claim 1, configured to be mounted on a base member.

7. The downhole seal according to claim 1, wherein at least one reaming element is mounted on a sleeve.

8. The downhole seal according to claim 1, wherein at least one reaming element is mounted on a sleeve, wherein the sleeve is configured to be located on a base member independently from the seal body.

9. The downhole seal according to claim 1, comprising a common sleeve configured to support both the seal body and at least one reaming element.

10. The downhole seal according to claim 1, wherein at least one reaming element is provided separately of the seal body.

11. The downhole seal according to claim 1, wherein at least one reaming element is located adjacent an axial end of the seal body.

12. The downhole seal according to claim 1, wherein at least one reaming element is located intermediate axial ends of the seal body.

13. The downhole seal according to claim 1, wherein at least one reaming element is located on or within the seal body.

14. The downhole seal according to claim 1, wherein at least one reaming element is at least partially embedded within the seal body.

15. The downhole seal according to claim 1, wherein at least one reaming element at least partially extends through the seal body.

16. The downhole seal according to claim 1, configured to be located within a wellbore defined by at least one of an a open drilled bore and a wellbore defined by a tubing string.

17. The downhole seal according to claim 1, comprising a plurality of reaming elements.

18. The downhole seal according to claim 1, wherein at least one reaming element is defined by a rib structure.

19. The downhole seal according to claim 1, wherein at least one reaming element is rigid.

20. The downhole seal according to claim 1, wherein at least one reaming element is generally spiral shaped.

21. The downhole seal according to claim 1, wherein at least one reaming element is generally annular.

22. The downhole seal according to claim 1, wherein at least a portion of the downhole seal is configured for rotation.

23. The downhole seal according to claim 1, wherein at least one reaming element defines a centraliser element configured to centralise the seal body within a wellbore.

24. The downhole seal according to claim 1, wherein the reaming element is configured to protect at least a portion of the seal body when the downhole seal is translated within a wellbore.

25. The downhole seal according to claim 1, comprising a protection element configured to protect at least a portion of the seal body when the downhole seal is translated within a wellbore.

26. The downhole seal according to claim 25, wherein the protection element defines at least one reaming element.

27. A method of establishing a seal within a wellbore, comprising: providing a downhole seal having a seal body and a reaming element; translating the downhole seal through a wellbore and reaming a portion of the wellbore with the reaming element; and exposing the swellable material to an activator to cause the seal body to swell to establish a seal.

28. A method of reaming a wellbore, comprising: providing a downhole tool comprising: a seal body comprising a swellable material configured to swell upon exposure to a swelling activator to establish a seal within a wellbore; and at least one reaming element; and translating the downhole tool through a wellbore to ream the wellbore with the at least one reaming element.

29. A downhole seal comprising: a seal body comprising a swellable material configured to swell upon exposure to a swelling activator to establish a seal within a wellbore; and at least one protection element configured to protect at least a portion of the seal body when the downhole seal is translated within a wellbore, wherein the protection element defines a reaming element configured to ream an internal surface of a wellbore.

30. A method of establishing a seal within a wellbore, comprising: providing a downhole seal having a seal body and a protecting element, wherein the seal body comprises a swellable material; translating the downhole seal through a wellbore, wherein the protection element protects the seal body; reaming a portion of the wellbore with the protection element; and exposing the swellable material to an activator to cause the seal body to swell to establish a seal.

Description:

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority from Great Britain Application No. 0906746.3, filed Apr. 20, 2009 incorporated by reference in its entirety.

BACKGROUND

The present invention relates to a downhole seal, and in particular, but not exclusively, to a downhole seal incorporating a swellable material and a reaming element configured to ream an internal surface of the wellbore.

Swelling seals for use in a downhole environment in the oil and gas industry are well known. These seals have numerous applications, such as for zonal isolation purposes, to facilitate compartmentalized fracing operations, to provide cement assurance and the like. Typically, a band of a swellable material is mounted on the outer surface of a tubular body, such as liner, production tubing etc. which is then run into a wellbore to a required depth, where exposure to a suitable swelling activator, such as oil or water, causes the swellable material to swell. This swelling is used to provide an annular seal between the tubular body and a wall of the wellbore—such a sealing arrangement is conventionally defined in the art as a packer.

Swelling seals of the type described above may be run into an open wellbore, such that the swelling seals are tripped through a bore with exposed rock. The drilling operation used to form the bore may produce a very coarse wall surface and may present regions of reduced diameter. There is therefore a risk that the swelling seals could be damaged by engagement with the rock of the open bore during transit therethrough.

Swelling seals may also be run through a tubing string, such as a casing string, liner string or the like. Tubing strings are often cemented in place within a drilled bore, which is achieved by pumping a cement slurry downward through the tubing string and then upward into an annulus formed between the tubing string and the wall of the drilled bore. It is possible for cement residue to adhere and cure on the internal wall of the tubing string. Such adhered cement may present a barrier to the passage of a swelling seal, and may potentially be a source of damage to the seal.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a downhole seal comprising:

a seal body comprising a swellable material configured to swell upon exposure to a swelling activator to establish a seal within a wellbore; and

at least one reaming element configured to ream an internal surface of a wellbore.

The reaming element may be configured to ream an internal surface of the wellbore while the downhole seal is being translated therein. Accordingly, translating the downhole seal, for example to reach a required location, may also permit a reaming operation within the wellbore to be achieved. This reaming operation may be utilised for cleaning purposes, improving the consistency of the bore diameter or the like.

The reaming element may be configured to ream a wall surface of a drilled bore. This may facilitate cleaning of the wellbore, creation of a uniform diameter of the wellbore or the like. For example, a wellbore formed by drilling may have a relatively uneven and course wall surface, which surface may be addressed by use of the reaming element of the downhole seal.

The reaming element may be configured to ream an internal wall surface of a tubing string. This may facilitate cleaning of the tubing string. For example, the reaming element may be configured to remove deposits from the tubing wall surface, such as deposits of cement which may remain adhered to the tubing wall surface following a cementing operation. Other deposits may include salts, tars and the like. The reaming element may also function as a wiper.

At least one reaming element may be configured to protect at least a portion of the seal body when the downhole seal is translated within a wellbore. In use, the downhole seal may be translated through a wellbore, for example to locate the seal at a desired location, wherein at least one reaming element provides protection to the seal body. For example, the reaming element may assist to prevent or minimise contact of the seal body with a wall surface of the wellbore, a blockage within the wellbore or the like. Once the swellable material is exposed to a swelling activator, the seal body will swell to establish a seal within the wellbore.

The seal body may be configured to swell from an unswollen configuration to a swollen configuration to establish a seal.

At least one reaming element may define an outer dimension which is greater than an outer dimension of the seal body when in an unswollen configuration. In this arrangement at least one reaming element may prevent or minimise contact of the seal body, when in its unswollen configuration, with a wall surface of a wellbore. This may advantageously provide protection for the seal body while in a configuration when translation through a wellbore is achievable or desirable.

At least one reaming element may define an outer dimension which is equal to or less than an outer dimension of the seal body when in a swollen configuration. This arrangement may assist to prevent or at least minimise the reaming element from interfering with the establishment of a seal by swelling of the seal body.

The outer dimension of at least one of the reaming element and the seal body may define an outer diameter.

The downhole seal may be configured to be mounted on a base member. The base member may comprise a downhole tubular, such as a casing tubular, liner tubular, production tubular or the like. The base member may form part of the downhole seal of the present invention.

The seal body may be configured to be mounted on the base member. The seal body may be configured to be mounted on an outer surface of the base member. The seal body may be configured to be mounted on an axial end portion of the base member. The seal body may be directly mounted on the base member, for example by being bonded thereto. The seal body may be indirectly mounted on the base member. For example, the seal body may be mounted on a sleeve configured to be mounted on the base member.

At least one reaming element may be mounted on the base member. At least one reaming element may be directly mounted on the base member. At least one reaming element may be integrally formed with the base member. At least one reaming element may be separately formed and directly secured to the base member.

At least one reaming element may be indirectly mounted on the base member. For example, the reaming element may be mounted on a sleeve configured to be mounted on the base member. At least one reaming element may be integrally formed with the sleeve.

In one embodiment at least one reaming element may be mounted on a sleeve, wherein the sleeve may be configured to be located on a base member independently from the seal body.

The downhole seal may comprise a common sleeve configured to support both the seal body and at least one reaming element. In this arrangement both the seal body and at least one reaming element may be mounted on a base member in a single operation.

At least one reaming element may be provided separately of the seal body. For example, at least one reaming element may be formed separately and mounted adjacent or in the region of the seal body.

At least one reaming element may be located adjacent an axial end of the seal body. At least one reaming element may be located intermediate axial ends of the seal body. At least one reaming element may be located on or within the seal body. At least one reaming element may be at least partially embedded within the seal body. At least one reaming element may at least partially extend through the seal body.

The downhole seal may be configured to be located within a wellbore defined by an a open drilled bore. The downhole seal may be configured to be located within a wellbore defined by a tubing string, such as a pipeline, casing string, liner string or the like.

A plurality of reaming elements may be provided.

At least one reaming element may be defined by a rib structure.

At least one reaming element may comprise a relatively hard material, such as tungsten carbide.

At least one reaming element may be generally spiral shaped. This arrangement may permit at least one reaming element to extend both circumferentially and axially.

At least one reaming element may be generally annular.

At least a portion of the downhole seal may be configured for rotation.

At least one reaming element may define a centraliser element configured to centralise the seal body within a wellbore.

The downhole seal may comprise at least one protection element configured to protect at least a portion of the seal body when the downhole seal is translated within a wellbore. At least one protection element may be configured to define a reaming element. Features defined above associated with at least one reaming element may apply to at least one protection element.

As defined above, the swellable material is configured to swell upon exposure to an activator. The activator may comprise a chemical activator, thermodynamic activator, electromagnetic activator, mechanical activator or the like. In embodiments of the present invention the swellable material may be configured to swell upon exposure to a material present within a wellbore. The material may comprise water, oil, gas or the like. The material may comprise an artificial material delivered into the wellbore, such as cement, drilling mud or the like. The material may comprise a naturally occurring material, such as water or hydrocarbons produced from a subterranean reservoir.

The downhole seal may be configured to function as a packer.

According to a second aspect of the present invention there is provided a method of establishing a seal within a wellbore, comprising:

providing a downhole seal having a seal body and a reaming element;

translating the downhole seal through a wellbore and reaming a portion of the wellbore with the reaming element; and

exposing the swellable material to an activator to cause the seal body to swell to establish a seal.

The reaming element may also function protect the seal body from engagement with a wall surface of the wellbore.

The downhole seal may be provided in accordance with the first aspect. Defined features and stated and implied methods of use of the downhole seal according to the first aspect apply to the method according to the second aspect.

According to a third aspect of the present invention there is provided a downhole tool comprising:

a seal body comprising a swellable material configured to swell upon exposure to a swelling activator to establish a seal within a wellbore: and

at least one reaming element configured to ream an internal surface of a wellbore.

The reaming element may be configured to ream an internal surface of the wellbore while the downhole tool is being translated therein. Accordingly, translating the downhole tool, for example to reach a required location at which to establish a seal, will also permit a reaming operation within the wellbore to be achieved. This reaming operation may be utilised for cleaning purposes, improving the consistency of the bore diameter or the like.

The reaming element may be configured to ream a wall surface of a drilled bore. The reaming element may be configured to ream an internal wall surface of a tubing string.

The downhole tool according to the third aspect may share features of the downhole seal according to the first aspect.

According to a fourth aspect of the present invention there is provided a method of reaming a wellbore, comprising:

providing a downhole tool comprising:

a seal body comprising a swellable material configured to swell upon exposure to a swelling activator to establish a seal within a wellbore; and

at least one reaming element; and

translating the downhole tool through a wellbore to ream the wellbore with the at least one reaming element.

The method may comprise establishing a seal within the wellbore using the seal body.

According to a fifth aspect of the present invention there is provided a method of manufacturing a downhole seal, comprising:

mounting a seal body comprising a swellable material on a base member; and

mounting a reaming element on the base member.

According to a sixth aspect of the present invention there is provided a downhole seal comprising:

a seal body comprising a swellable material configured to swell upon exposure to a swelling activator to establish a seal within a wellbore; and

at least one protection element configured to protect at least a portion of the seal body when the downhole seal is translated within a wellbore, wherein at least one protection element defines a reaming element configured to ream an internal surface of a wellbore.

According to a seventh aspect of the present invention there is provided a method of establishing a seal within a wellbore, comprising:

providing a downhole seal having a seal body and a protecting element, wherein the seal body comprises a swellable material;

translating the downhole seal through a wellbore, wherein the protection element protects the seal body;

reaming a portion of the wellbore with the protection element; and

exposing the swellable material to an activator to cause the seal body to swell to establish a seal.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic representation of a downhole seal in accordance with one embodiment of the present invention;

FIG. 2 is cross-sectional view of the downhole seal of FIG. 1, wherein the left side of FIG. 2 represents the seal in a run-in configuration, and the right side of FIG. 2 represents the seal in a sealed configuration;

FIG. 3 is a diagrammatic representation of a downhole seal in accordance with an alternative embodiment of the present invention;

FIG. 4 is a cross-sectional view of a possible configuration of protection elements of the downhole seal of FIG. 3, wherein the left side of FIG. 4 represents the seal in a run-in configuration, and the right side of FIG. 4 represents the seal in a sealed configuration;

FIG. 5 is a cross-sectional view of another possible configuration of protection elements of the downhole seal of FIG. 3, wherein the left side of FIG. 5 represents the seal in a run-in configuration, and the right side of FIG. 5 represents the seal in a sealed configuration; and

FIG. 6 is a diagrammatic representation of a downhole seal in accordance with a further embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

A downhole seal, generally identified by reference numeral 10, according to an embodiment of the present invention is shown in FIG. 1. As will be described in further detail below, the downhole seal 10 is configured to provide a seal within a wellbore, in addition to perform a reaming operation within the wellbore. Accordingly, the downhole seal 10 may equally be defined as a downhole tool.

The downhole seal 10 is mounted on a tubular body 12 forming part of a tubing string. In the example disclosed the tubular body includes a liner tubular. The seal 10 includes a seal body 14 which comprises a swellable material configured to swell upon exposure to a swelling activator, such as oil or water. The seal 10 further includes a pair of sleeves or collars 16 disposed on the tubular body 12 at axially opposite ends of the seal body 14, wherein the sleeves 16 are secured to the tubular body 12 via a number of screws 18.

Each sleeve 16 carries a plurality of spiral reaming elements 20, which as will be described in detail below are used in the present exemplary embodiment to protect the seal body 14 and to function to ream an internal wall surface of a wellbore.

Reference is now made to FIG. 2 in which the downhole seal 10 is shown, in cross-section, in use within a wellbore 22. In the embodiment shown the wellbore 22 is an open drilled bore. For convenience and brevity, the left side of FIG. 2 shows the seal 10 in a run-in configuration, and the right side of FIG. 2 shows the seal 10 in a sealing configuration.

The reaming elements 20 describe an outer diameter which is greater than that of the seal body when in an unswollen configuration, as shown in the left side of FIG. 2. Accordingly, the reaming elements 20 function to prevent the seal body 14 from contacting the wall 24 of the wellbore 22, and thus assist to minimise damage to the seal body 14 while being translated through the wellbore 22.

Additionally, it is often the case that a drilling operation produces a bore with a very course or uneven wall surface, which may include bore restrictions 26, for example. Such bore restrictions 26 are undesirable for many reasons, which may include obstructing the passage of an object therethrough, damaging a passing object, preventing uniform circulation of cement, and preventing coaxial alignment of tubing, for example, within the wellbore. Translation of the seal 10 through the wellbore 22 will effect reaming of the bore wall 24 which will assist to remove bore restrictions 26 and provide a more even bore wall surface 24. It should be noted that the reaming operation may be assisted by rotating the tubular member 12, with torque transmitted to the sleeves 16 through the screws 18.

Once the seal 10 is located at the required depth within the bore 22, exposure of the swellable material to a swelling activator will cause the seal body 14 to swell and establish a seal within an annulus 28 defined between the tubular body 12 and the wall 24 of the wellbore 22, as demonstrated in the right hand side of FIG. 2.

The sleeves 16 may function as anti-extrusion rings, for example where significant swelling pressure is present, or where a significant pressure differential is present across the established seal. That is, the sleeves 16 may assist to prevent extrusion of the seal body 14 along the annulus 28 due to elevated pressures and/or pressure differentials.

Reference is now made to FIG. 3 in which there is shown a downhole seal, generally identified by reference numeral 40, in accordance with an alternative embodiment of the present invention. The downhole seal 40 is mounted on a tubular body 42 and includes a seal body 44 which comprises a swellable material. A plurality of spiral reaming elements 46 are disposed within the seal body 46, which, similar to reaming elements 12 in the embodiment first shown in FIG. 1, function to ream a wall surface of a wellbore, while protecting the seal body 44 from damage.

The reaming elements 46 may be disposed within the seal body 46 in a number of configurations. Two such exemplary configurations are described below, with reference to FIGS. 4 and 5. These configurations are described with reference to downhole seals, shown in cross-section in FIGS. 4 and 5, and identified by respective reference numerals 40a and 40b. The downhole seals 40a, 40b are shown in use within a drilled wellbore 52.

Referring first to FIG. 4, the downhole seal 40a with reaming elements 46a arranged in accordance with a first configuration will be described. It should be noted that for convenience and brevity the seal 40a is shown in a run-in configuration in the left hand side of FIG. 4, and in a sealing configuration in the right hand side of FIG. 4.

The reaming elements 46a are embedded and supported within the seal body 44a so as to protrude therefrom when the seal body 44a is in an unswollen configuration, as shown in the left side of FIG. 4. The protruding reaming elements 46a may therefore prevent the seal body 44a from engaging the wall surface 54 of the wellbore 52, and also effect reaming of the bore wall 54 when the seal 40a is translated through the wellbore 52.

Once the downhole seal 40a is located at the required depth within the wellbore 52 the seal body 44a may swell upon exposure to a swelling activator to establish a seal within the annulus 58 defined between the tubular body 42a and the bore wall 54, as shown in the right side of FIG. 4. As shown in FIG. 4, the seal body 44a envelops the reaming elements 46a when the seal body 44a is swollen.

Referring now to FIG. 5, the downhole seal 40b with reaming elements 46b arranged in accordance with a second configuration will be described. It should be noted that for convenience and brevity the seal 40b is shown in a run-in configuration in the left hand side of FIG. 5, and in a sealing configuration in the right hand side of FIG. 5.

The reaming elements 46b are formed integrally with a sleeve 60 which is mounted on and secured to the tubular body 42b. The seal body 44b is mounted on the outer surface of the sleeve 60 and the reaming elements 46b extend radially outwardly from the sleeve 60 and through the seal body 44b. The reaming elements 46b protrude from the outer surface of the seal body 44b when the seal body 44b is in an unswollen state, as shown in the left side of FIG. 5. The protruding reaming elements 46b may therefore prevent the seal body 44b from engaging the wall surface 54 of the wellbore 52, and also effect reaming of the bore wall 54 when the seal 40b is translated through the wellbore 52.

Once the downhole seal 40b is located at the required depth within the wellbore 52 the seal body 44b may swell upon exposure to a swelling activator to establish a seal within the annulus 58 defined between the tubular body 42b and the bore wall 54, as shown in the right side of FIG. 5. As shown in FIG. 5, the seal body 44b envelops the reaming elements 46b when the seal body 44b is swollen

In the embodiments described above the downhole seal is mounted on a tubular body forming part of a tubing string. This tubular body may be any downhole tubular, such as a tubular around 9.14 m (30 feet) long. It may not be desirable, however, to provide a seal on such a tubing length, as this may present supply problems, handling problems, increase costs and the like. Referring to FIG. 6, a downhole seal, generally identified by reference numeral 70, according to an embodiment of the present invention may be mounted on and form part of a pup-joint tubular 72, which are known in the art, and typically have a length of around 0.91 m (3 feet), although other lengths are possible. The pup-joint tubular 72 comprises connectors 74 at either end thereof, permitting connection within a larger tubing string. Suitable connectors 74 are well known in the art, and may include threaded connectors. The provision of a downhole seal 70 in combination with a pup-joint tubular 72 may permit flexibility of the present invention to be incorporated, relatively easily, within a tubing string being run into a wellbore.

It should be understood that the embodiments described herein are merely exemplary and that various modifications may be made thereto without departing from the scope of the present invention. For example, reaming elements may be provided both separately of the seal body, as shown in FIG. 1, and also as part or embedded within the seal body, as shown in FIG. 3. Additionally, the reaming elements may be provided in any configuration, and for example may not be spiral shaped. For example, the reaming elements may be generally annular. Furthermore, the reaming elements may alternatively, or additionally function to centralise the downhole seal within a wellbore.

In the embodiments described above the downhole seals are shown in use within an open drilled bore. However, the downhole seal of the present invention has application within a tubing string, such as a pipeline, casing string, liner string, production string or the like. In such examples the reaming elements may be configured to remove deposits, such as cement, salts and the like, formed on the internal surface of the tubing string.

Additionally, a plurality of downhole seals may be provided in combination along the length of a tubular or tubing string.