Downhole sealing assembly with swellable seal

Abstract

A downhole sealing assembly comprises a sleeve adapted to be mounted on a tubular body disposable within a bore, the sleeve (12) including a swellable material and defining a sealing arrangement comprising inner and outer seals. Swelling of the material radially extends the inner seal into contact with the tubular body and extends the outer seal into contact with the bore.

Claims

1. A sealing assembly configured to be deployed downhole comprising a sleeve adapted to be mounted on a tubular body, both of which are disposable within a bore, the sleeve including a swellable sealing arrangement comprising a swellable material and inner and outer seals mounted, in a first configuration prior to swelling, on inner and outer surfaces of the sleeve respectively, wherein the inner seal extends along a partial axial length of the sleeve, and whereby the swellable sealing arrangement is configured such that, in a second configuration, swelling of the swellable material causes the inner seal to extend radially inwardly from the inner surface of the sleeve so as to make sealing contact with the mounted tubular body and establish a seal between the sleeve and the mounted tubular body, and further causes the outer seal to extend radially outwardly from the outer surface of the sleeve so as to make sealing contact with a wall of the bore and establish a seal between the sleeve and the wall of the bore.

2. The assembly of claim 1, wherein the assembly is adapted to function as a packer.

3. The assembly of claim 1, wherein the assembly is adapted to be retrofitted to an existing tubular body.

4. The assembly of claim 1, wherein the sleeve is adapted to be slidably mounted on the body.

5. The assembly of claim 1, comprising fixings for fixing the sleeve to the body.

6. The assembly of claim 1, comprising at least one stop for mounting on the body and limiting axial movement of the sleeve on the body.

7. The assembly of claim 1, wherein the sleeve defines a connector adapted to connect at least two bodies together.

8. The assembly of claim 1, wherein the swellable material is adapted to swell at least in part by volumetric expansion thereof.

9. The assembly of claim 1, wherein the swellable material is adapted to swell upon exposure to an activator.

10. The assembly of claim 1, wherein the outer and inner seals comprise identical swellable material.

11. The assembly of claim 1, wherein the outer and inner seals comprise different swellable materials.

12. The assembly of claim 1, wherein the sleeve comprises a structural element and an outer surface of the sleeve structural element defines a recess adapted to receive and accommodate at least a portion of the outer seal.

13. The assembly of claim 1, wherein the sleeve comprises a structural element and an inner surface of the sleeve structural element defines a recess adapted to receive and accommodate at least a portion of the inner seal.

14. The assembly of claim 1, wherein the inner seal comprises a smaller depth of swellable material than the outer seal.

15. The assembly of claim 1, wherein the outer and inner seals are separately formed.

16. The assembly of claim 1, wherein the outer and inner seals are integrally formed.

17. The assembly of claim 1, wherein the sealing arrangement is moulded onto the sleeve.

18. The assembly of claim 1, wherein the sealing arrangement extends over an axial end face of the sleeve between inner and outer surfaces thereof.

19. The assembly of claim 18, wherein the sealing arrangement extends over opposed axial end faces of the sleeve between inner and outer surfaces thereof.

20. The assembly of claim 1, comprising a plurality of sealing arrangements.

21. The assembly of claim 20, wherein a sealing arrangement is mounted on each end region of the sleeve.

22. The assembly of claim 20, wherein the swellable material within each sealing arrangement is identical.

23. The assembly of claim 20, wherein the sealing arrangements comprise different sealing materials.

24. The assembly of claim 23, wherein the swellable material in one sealing arrangement is adapted to swell when exposed to water, and the swellable material in another sealing arrangement is adapted to be activated when exposed to hydrocarbons.

25. The assembly of claim 1, comprising a centraliser.

26. The assembly of claim 25, wherein the centraliser is mounted on the sleeve between two sealing assemblies.

27. The assembly of claim 25, wherein the centraliser comprises a material selected to reduce friction between the assembly and an adjacent bore wall.

28. The assembly of claim 25, wherein the centraliser is colour-coded to reflect a feature of the assembly.

29. The assembly of claim 28, wherein the centraliser is colour-coded to reflect the triggering fluid for the swellable material.

30. The assembly of claim 1, wherein the swellable material comprises a swelling elastomer and the thickness of elastomer provided is selected to provide a predetermined degree of unused swell.

31. The assembly of claim 30, wherein the degree of unused swell of the inner and outer seals is selected to provide a substantially balanced pressure force on the sleeve.

32. The assembly of claim 1, wherein the inner seal extends along a partial axial length of the sleeve such that the inner seal defines a terminating end which is positioned intermediate opposite axial ends of the sleeve.

33. The assembly of claim 1, wherein the inner seal extends along a partial axial length of the sleeve such that the assembly comprises: a first sealing arrangement mounted on a first axial end region of the sleeve, wherein the first sealing arrangement includes an outer seal and an inner seal; a second sealing arrangement mounted on a second axial end region of the sleeve, wherein the second sealing arrangement includes an outer seal and an inner seal, wherein the inner seals of the first and second sealing arrangements are axially separated from each other.

34. The assembly of claim 33, wherein an inner surface of the sleeve located between the inner seals of the first and second sealing arrangements is free from any sealing material.

35. The assembly of claim 1, wherein the sleeve is non-expandable.

36. A sealing assembly configured to be deployed downhole, the assembly comprising: a sleeve adapted to be mounted on a tubular body disposable within a bore; a swellable sealing arrangement comprising, in a first configuration, an outer seal mounted on an outer surface of the sleeve; and an inner seal mounted on an inner surface of the sleeve, wherein the inner seal extends along a partial axial length of the sleeve; and whereby the swellable sealing arrangement is configured such that, in a second configuration, swelling of the swellable material causes the inner seal to extend radially inwardly from the inner surface of the sleeve so as to make sealing contact with the mounted tubular body to establish a seal between the sleeve and the mounted tubular body, and further causes the outer seal to extend radially outwardly from the outer surface of the sleeve so as to make sealing contact with a wall of the bore and establish a seal between the sleeve and the wall of the bore.

37. A method of providing a downhole seal, the method comprising: mounting a sleeve over a tubular body, wherein the sleeve comprises a sealing arrangement having an outer seal mounted onto an outer surface of the sleeve and an inner seal mounted onto an inner surface of the sleeve facing the tubular body and the inner and outer seals comprise a swellable material, and wherein the inner seal extends along a partial axial length of the sleeve; and running the body and the sleeve mounted thereon downhole into a bore; activating the outer seal to swell to radially outwardly extend into sealing contact with a wall of the bore and to thereby form a seal between the sleeve and the wall of the bore; and activating the inner seal to swell to radially inwardly extend into sealing contact with the tubular body and to thereby form a seal between the sleeve and the body.

38. A sealing assembly configured to be deployed downhole comprising: a sleeve adapted to be mounted over an outer surface of a tubular body, wherein the tubular body and the mounted sleeve are configured to be disposed within a bore, wherein the sleeve having an inner surface which, when the sleeve is mounted over the tubular body, is configured to face the outer surface of the tubular body and be spaced apart therefrom, and the sleeve having an outer surface configured to face a wall of a bore; an inner swellable seal mounted to the inner surface of the sleeve, wherein the inner swellable seal extends along a partial axial length of the sleeve, and whereby the inner swellable seal has a thickness selected so that when the sleeve is mounted over the tubular body and the inner seal is exposed to an activator medium, the inner swellable seal is configured to swell radially inwardly from the inner surface of the sleeve on which it is mounted into sealing contact with the outer surface of the tubular body to thereby form a seal between the inner surface of the sleeve and the outer surface of the body; and an outer swellable seal mounted to the outer surface of the sleeve, the outer swellable seal having a thickness selected so that when the outer swellable seal is exposed to the activator medium, the outer swellable seal is configured to swell radially outwardly from the outer surface of the sleeve on which it is mounted into sealing contact with a wall of the bore to thereby form a seal between the outer surface of the sleeve and the wall of the bore.

39. A method of providing a seal configured to be deployed downhole, the method comprising: mounting a sleeve over an outer surface of a tubular body that is configured to be disposed within a bore, wherein the sleeve having an inner surface which, when the sleeve is mounted over the tubular body, is configured to face the outer surface of the tubular body and be spaced apart therefrom, and the sleeve having an outer surface configured to face a wall of a bore when both the body and the mounted sleeve are deployed downhole in the bore, the sleeve further comprising an inner swellable seal mounted to the inner surface of the sleeve wherein the inner seal extends along a partial axial length of the sleeve, the inner swellable seal having a thickness selected so that when the sleeve is mounted over the tubular body and the inner seal is exposed to an activator medium, the inner swellable seal is configured to swell radially inwardly from the inner surface of the sleeve into contact with the outer surface of the tubular body to thereby form a seal between the inner surface of the sleeve and the outer surface of the body, the sleeve further comprising an outer swellable seal mounted to the outer surface of the sleeve, the outer swellable seal having a thickness selected so that when the outer swellable seal is exposed to the activator medium, the outer swellable seal is configured to swell radially outwardly from the outer surface of the sleeve into contact with a wall of the bore to thereby form a seal between the outer surface of the sleeve and the wall of the bore; running the body with the sleeve mounted thereon downhole into a bore having a wall; exposing the outer seal to the activator medium to thereby cause the outer seal to swell radially outwardly into sealing contact with the wall of the bore to thereby form a seal between the outer surface of the sleeve and the wall of the bore; and exposing the inner seal to the activator medium to thereby cause the inner seal to swell radially inwardly into sealing contact with the outer surface of the body to thereby form a seal between the inner surface of the sleeve and the outer surface of the body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) 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:

(2) FIG. 1 is a longitudinal cross sectional view of a sealing assembly according to an embodiment of the present invention;

(3) FIG. 2 is a diagrammatic representation of two of the sealing assemblies of FIG. 1, shown mounted on a tubing string and positioned within a wellbore;

(4) FIG. 3 is a further diagrammatic representation of the sealing assemblies and tubing string shown in FIG. 2, wherein the sealing assemblies are shown in a sealing configuration;

(5) FIG. 4 is a longitudinal cross-sectional view of a portion of a sealing assembly according to an alternative embodiment of the present invention; and

(6) FIG. 5 is a lateral cross-sectional view of the sealing assembly of FIG. 4, taken along line 5-5 of FIG. 4, wherein the sealing assembly is shown mounted on a tubular body.

DETAILED DESCRIPTION OF THE DRAWINGS

(7) Reference is first made to FIG. 1 of the drawings in which there is shown a longitudinal cross-sectional view of a sealing assembly, generally identified by reference numeral 10, in accordance with an embodiment of the present invention. The sealing assembly 10 comprises a sleeve 12 which, as will be described in further detail below, is adapted to be mounted on a body, such as a tubular body. A first sealing arrangement 14 is mounted on one axial end of the sleeve 12, and a second sealing arrangement 16 is mounted on an opposite axial end of the sleeve 12.

(8) The first sealing arrangement 14 comprises an outer seal 18 which circumferentially extends around the outer surface of the sleeve 12, and an inner seal 20 which circumferentially extends around the inner surface of the sleeve 12, wherein the outer and inner seals 18,20 are integrally formed such that the sealing arrangement 14 extends over an axial end face 22 of the sleeve 12. Similarly, the second sealing arrangement 16 also comprises an outer seal 24 mounted on the outer surface of the sleeve 12 and an integrally formed inner seal 26 mounted on an inner surface of the sleeve 12 such that the second sealing arrangement 16 extends over an opposite axial end face 28 of the sleeve 12.

(9) The outer and inner seals 18,24,20,26 of the first and second sealing arrangements 14,16 are formed of a swellable material, such as a swellable elastomer. The swellable material is adapted to swell when exposed to a particular activator. In the embodiment shown the swellable material forming both the first and second sealing arrangements 14,16 is adapted to be activated to swell when exposed to water. However, it should be understood that any swelling material or combination of materials may be utilised in accordance with user requirements.

(10) In use, the sealing assembly 10 is mounted on the outer surface of a body (not shown), such as a production tubing string, and is subsequently run downhole into a wellbore. When the swellable material of the first and second sealing arrangements 14,16 is exposed to a particular activator, which as noted above in this embodiment is water, the material will be activated to swell causing the outer seals 18,24 to expand radially outwardly and the inner seals 20,26 to expand radially inwardly. Accordingly, the expanded outer seals 18,24 may form a seal against the wall surface of the wellbore, and the expanded inner seals 20,26 may establish a seal against the outer surface of the body upon which the sealing assembly 10 is mounted.

(11) It will be noted from FIG. 1 that the elastomer forming the outer seals 18, 24 is significantly thicker than the elastomer forming the inner seals 20, 26, and also has a greater axial extent. This reflects the greater demands placed on the outer seals 18, 24, which much extend further to achieve contact with the opposing sealing surface, and which may also be seeking to achieve a sealing contact with an unlined bore wall. In contrast, the inner seals 20, 26 will typically only need to bridge a small gap, perhaps 30-60 thousands of an inch, to contact the surface of the body on which the assembly is mounted. It will also be noted that the outer diameter of the structural metal sleeve 12 has a reduced outer diameter spaced from the sleeve ends, which permits a greater depth of elastomer to be moulded onto the sleeve 12 while still maintaining a constant outer seal diameter. This provides for greater swelling capacity of the outer seals.

(12) The sealing assembly 10 may therefore establish an effective annulus seal such that fluid migration along an annulus defined between the wall of the bore and the outer surface of the body will not be permitted past the sealing assembly 10. Additionally, the downhole sealing assembly 10 may therefore also be used to prevent migration of fluids from the surrounding earth into the wellbore, or alternatively, or additionally the loss of fluids from the wellbore into the surrounding earth. Of course the assembly 10 will also be effective to prevent sand migration.

(13) The sealing assembly 10 further comprises a centraliser collar 30 mounted on the outer surface of the sleeve 12 and interposed between the first and second sealing arrangements 14,16. The centraliser collar 30 is secured to the sleeve 12 via studs 32 which threadably engage respective bores 34 extending through the wall of the sleeve 12.

(14) The centraliser collar 30 describes a slightly larger diameter than that of the first and second sealing arrangements when in an unexpanded state. Accordingly, the centraliser collar 30 will function to centralise the sealing assembly 10 and the body upon which the sealing assembly 10 is mounted within a wellbore, and will also protect the outer seals 18, 24 from wear and damage.

(15) It will be understood by those of skill in the art that the sealing assembly 10 of the present invention may be utilised in a number of downhole applications where an annulus seal is required. However, an example of one use of the sealing assembly 10 is described below with reference to FIGS. 2 and 3.

(16) Referring initially to FIG. 2, there is diagrammatically shown a portion of a production tubing string 36 which has been run into a horizontal wellbore section 38 and which comprises two of the sealing assemblies shown in FIG. 1. The sealing assemblies are generally identified by reference numerals 10a and 10b. The wellbore 38 extends through an oil bearing formation 40 which is positioned above a water bearing formation 42 and separated therefrom via an oil water interface 44.

(17) Accordingly oil from formation 40 may migrate into the wellbore 38 and subsequently into the production tubing string 36 through slotted production tubulars 46, for example. However, the wellbore 38 may extend through formation fractures 48 which permit migration of water from formation 42 into the wellbore 38. If left unattended, water will therefore also enter the production string 36 and be produced to surface with the oil, which is undesirable. Furthermore, both oil and water may migrate along the annulus 50 formed between the production string 36 and the inner wall surface 52 of the wellbore 38 which is also undesirable. Such undesirable migration of fluids into and through the wellbore 38 may be prevented by the sealing assemblies 10 of the present invention when these are activated to establish appropriate seals within the wellbore 38, which will now be discussed in detail with reference to FIG. 3.

(18) The first and second sealing arrangements 14,16 of each sealing assembly 10 have been activated to swell and expand upon contact with fluids within the wellbore 38. It should be noted that the swellable material may differ between each sealing assembly 10a, 10b, and also between each sealing assembly 12,14 of each sealing assembly 10a, 10b. The expanded sealing arrangements 14, 16 therefore establish seals within the annulus 50, and also between each sealing assembly 10 and the outer surface of the tubing string 36. Accordingly, migration of fluids along the annulus past the sealing assemblies 10 will be prevented. Furthermore, as sealing assembly 10b is positioned adjacent the formation fractures 48, these fractures may be closed to the wellbore 38. Accordingly, the sealing assembly 10b therefore prevents migration of water from formation 42 into the wellbore 38. As such, the volume of water produced to surface with the oil may be significantly minimised.

(19) It will be appreciated that additional sealing assemblies may be mounted along the length of the production string 36 in accordance with user requirements. Additionally, further sealing assemblies of the present invention may be mounted on the production tubing 36 in order to span the full extent of the formation fractures 48 to therefore completely seal the wellbore 38 at this location within the wellbore 38.

(20) Reference is now made to FIG. 4 of the drawings in which there is shown a longitudinal cross-sectional view of an end portion of a sealing assembly, generally identified by a reference numeral 60, in accordance with an alternative embodiment of the present invention. The sealing assembly 60 comprises a sleeve 62 which in use is adapted to be mounted on the outer surface of a body (not shown). A plurality of slots 64 extend through the wall of the sleeve 62 from an outer to an inner surface thereof, wherein the slots 64 are circumferentially distributed about an end region of the sleeve 62. A swellable sealing material 66 is circumferentially mounted around the outer surface of the sleeve 62 and extends into the slots 64. It should be noted that the opposite axial end of the sealing assembly 60 corresponds to the axial end shown in FIG. 4. Accordingly a sealing arrangement may be formed on either end region of the sleeve 62.

(21) Reference is now made to FIG. 5 of the drawings in which there is shown a lateral cross-sectional view of the sealing assembly 60 shown in FIG. 4, taken through line 5-5, wherein the sealing assembly 60 is shown in FIG. 5 mounted on a tubular body 68. In use the tubular body 68 and sealing assembly 60 may be run into a wellbore, such as wellbore 38 shown in FIGS. 2 and 3. When the swellable material 66 is exposed to its particular activator, such as water, the material 66 will be caused to swell to expand radially outwardly and thus form a seal with the wall of the wellbore. Additionally, the material 66 will be caused to swell radially inwardly and through the slots 64 to therefore engage the outer surface of the tubular body 68. Swelling of the material 66 may occur until the entire annular space formed between the tubular body 68 and the sleeve 62 is filled, such that a seal may be established.

(22) It should be understood that the embodiments described above are merely exemplary and that various modifications may be made thereto without departing from the scope of the invention.

(23) For example, in the sealing assembly 10 first shown in FIG. 1, the outer and inner seals of each sealing arrangement are integrally formed. However, in alternative arrangements the outer and inner seals may be separately formed and subsequently secured together. Alternatively further, the outer and inner seals of each sealing arrangement may be mounted separately and in non-contact relationship relative to each other.

(24) Further, additional outer and/or inner seals may be provided along the length of the sleeve. Alternatively, a single sealing arrangement may be provided which extends along the full axial length of at least one of the outer and inner surfaces of the sleeve.

(25) Additionally, in the embodiments described above the sleeve is adapted to be slidably mounted on a body. However, the sleeve may alternatively be threadably mounted on a body. Furthermore, the sleeve may function as a connector to connect together two separate bodies. For example, an inner surface of the sleeve of the sealing assembly may incorporate appropriate threads which are adapted to engage corresponding threads on the bodies to be connected together.