Seal

Abstract

An annular sealing element to seal between metal surfaces for use in flanges, joints, packers and the like, located in oil and gas exploration and production equipment. The sealing element has inner and outer metal deformable surfaces joined at ends, defining an interior volume which is entirely filled with a plastic deformable material. The surfaces are arranged such that on compression of the element from the ends, the element will deform in a controlled manner on a cantilever principle. The volume of filler and the interior volume remain substantially equal during compression so that delamination does not occur. Thus the sealing element provides a seal combining the flexibility of elastomer seals with the integrity of a metal to metal seal.

Description

38 18 while the inner peaks meet the surface 34 of the tool body 16. A seal is thus formed between the tool 16 and the casing 38 18. Additionally the seal 12 now anchors the tool 10 against the casing 38 18 at this location. The seal 12 is set. The seal 12 provides a cantilever structure from the overhangs at lips 56,62. The filler 28 located now in the two chambers 46a,b supports the seal and prevents any collapsing as additional force is applied from the cone 50, and across the seal from the casing 18. Slips 64,66 have been forced up the slopes 54,60 to provide additional anchorage to the tool 10.

Sealing element 12 has ridges 68 located upon its outer surface 40. The ridges 68 bite into the casing 38 18 in order to effect the seal. A sealant material, Teflon®, is located between the ridges 68 to provide an improved seal if the primary metal seal of the ridges 68 fail. This is described with reference to FIG. 6 5.

The tool 10 can be retrieved from the well bore, by moving the ends 24,26 apart via movement of one or both of the cones 50,58. Separation of the ends 24,26 pulls the seal longitudinally and the seal 12 returns close to its original shape. A space 14 is thus created between the tool 10 and the casing 18 so that the work string can be pulled from the hole.

Referring now to FIG. 3, there is illustrated a sealing element, generally indicated by reference numeral 112, according to a preferred embodiment of the present invention. Like parts to the sealing element 12 of FIGS. 1 and 2 have been given the same reference numeral with the addition of one hundred. Sealing element 112 operates in an identical manner to sealing element 12 in providing a seal between two surfaces. For ease of interpretation, ends are shown held in opposed fixings 148a,b as described hereinbefore with reference to FIGS. 1 and 2.

Sealing element 112 comprises a continuous cylindrical annulus which may be described as a torus. The element 112 is formed from two metal sleeves, a first 120 being arranged inside and coaxial with a second 122. The sleeves, 120,122 are joined at upper 124 and lower 126 ends by having adjacent sides of the sleeves meeting over a short distance. The ends 124,126 of the sleeves 120,122 are held together by the fixing elements 148a,b. A resultant interior volume 130 is created which is entirely hounded by the sleeves 120,122 and the ends 124,126. The interior volume 130 is completely filled with a filler 128. The filler 128 contacts the sleeves 120,122 and ends 124,126. Each sleeve 120, 122 is formed of a metal continuous metal strip. The metal is preformed into a shape calculated to deform in a predetermined manner when the ends 124,126 are brought together. The inner sleeve 120, in longitudinal cross-section, has a surface 132 which is symmetrically shaped through a horizontal plane equidistant from the ends 124,126. The surface 132 forms a series of peaks and troughs. There are two troughs 138a,b which comprise opposing sloping surfaces, bounding a single peak 136 which is a plateau bounded by the sloping surfaces of the troughs 138a,b. The outer sleeve 122 has a profile 134 in reverse to the inner sleeve 120 with respect to the element 112. There are not distinct peaks 142a,b, opposing the troughs 138a,b. These have been levelled to provide a sharp sloping surface into the trough 144 opposite the peak 138. Each surface 132,134 is made up of a series of straight sections so that the metal of the sleeve can be bent along fold lines to create the shape required. In longitudinal cross-section through the torus, a polygon is created which defines the interior volume 30 and the volume of filler 128.

By mirroring the profiles of the sleeves 120,122, when the ends 124,126 are brought together the interior volume 130 remains substantially constant while the shape of the sleeves 120,122 ie. the polygon, deforms in a manner to accentuate the peaks and troughs. As the interior volume 130 remains substantially constant the filler 128 will deform with the element 112, but will remain in contact with the entire inside surface of the sleeves 120,122 at all times. In this way delamination is prevented which would otherwise cause air pockets in the seal, weakening its ability to withstand both longitudinal pressure applied from the ends 124,126 and transverse pressure applied horizontally between the sleeves 120,122.

Reference is now made to FIG. 4 of the drawings which illustrates the seal 112 of FIG. 3 when the ends 124,126 have been brought toward each other. This represents the seal 112 in the ‘set’ position. Like parts to those of FIG. 3 have been given the same reference numeral to aid clarity. It can be seen that the peaks 142a,b now sit proud of the fixing elements 148a,b. As the peaks 136, 138, 142 are plateau like, they provide planar surfaces to improve the sealing properties of the element 112. The area of contact of the sealing element 112 is thus predetermined by the dimension of the peaks 136, 138, 142 in the shape of the original sleeves 120,122. Further the arrangement of opposing peaks and troughs, with a trough 144/peak 136 on the horizontal plane bounded by symmetrically arranged peaks 142 and troughs 138, provides a cantilever structure which strengthens the sealing element 112.

As described herein with reference to FIGS. 1 and 2 the peaks 142a,b on the outer sleeve 122 may include ridges or other material to improve the grip of the sealing element 112 when these positions contact a surface within a well bore. Such additional features are illustrated with reference to FIG. 5.

FIG. 5 shows a part cross-sectional view through the outer sleeve 22 of a sealing element 12. Like parts to those of FIGS. 1 and 2 have been given the same reference numeral to aid clarity. Outer surface 40 of the sleeve 22 has a number of ridges 68a,b located thereon. The ridges 68 are protrusions extending from the surface. While they are illustrated as triangular in cross-section, it will be understood that a variety of forms could be used as long as they provide a ‘bite’ for the seal 12 against the second surface (not shown).

Located between the ridges 68a,b on a portion 70 of the surface is a sealant material 72. The material 72 can be a coating or may be a treatment applied to the surface 70. The coating could be metal, plastic or another material which will conform to the second surface on contact. While the material 72 is shown as only located between the ridges 68 it will be understood that the ridges could additionally or independently be coated. Teflon® or the like, would be a suitable material 72.

A further feature of the surface 40 is in the provision of a groove 74 for an insert 76. At discrete locations over the surface 40, grooves 74 in the form of indents can be arranged. Into each groove 74 an insert 76 is fitted. It will be appreciated that any suitable technique may be used for attaching the insert 76 to the groove 74. The insert 76 is a metal, which is preferably a ductile, inert metal, such as gold. In use, the insert 76 would be the primary seal, instead of the outer surface 40 or the sealant material 72. The ductile insert 76 will deform to accommodate any scratches or other discontinuities, which the outer surface 40 may not.

A further example application of use of the sealing element of the present invention, is in an expansion joint. FIG. 6 illustrates an expansion joint, generally indicated by reference numeral 310, as may be found in a tool string run in a well bore. The joint 310 operates by allowing one portion, such as a sleeve 313 to move axially relative to the mandrel 315. A seal 312 is located between the moving parts with a pressure differential between the outside and the tubing string. The seal 312 is as described hereinbefore with reference to FIGS. 1-4. The seal 312 is held on a mandrel 315, within a seal bore 317. Alternatively, the seal could be held on a housing, with a moveable mandrel. The seal 312 is activated by applying a pre-load to deform it slightly. A threaded ring 319 is used to apply the pre-load, but other methods could be equally be used. The surface of the seal bore 317 is treated in such a manner that friction and wear are minimised. This could be done with tungsten carbide coating or other such methods, which are well understood. In use, the seal 312 slides within the seal bore 317, maintaining a dynamic seal during axial movement of the mandrel 315 within the stationary seal bore 317.

Reference is now made to FIGS. 7(a) and 7(b), illustrating a sealing element, generally indicated by reference numeral 412, being used as a flange sealing ring. When flanges 421a,b are brought together to join adjacent pipe sections 423a,b, a seal is needed to prevent the escape of fluid from the pipe bore 425. Each flange 421a,b includes a circular groove 427a,b located on the surface 429a,b of the flange plate 431a,b. The seal 412 is sized to locate within the grooves 427a,b. Indeed the grooves 427a,b are profiled to match the outer surface of the ends 424,426 of the seal 412. Sealing between the flanges 421a,b is achieved at the first surface, being a combination of the inner edges 433a,b of the grooves 427a,b respectively, and the second surface, being a combination of the outer edges 435a,b of the grooves 427a,b respectively.

Sealing element 412 is as described with reference to FIGS. 1-4, comprising an annular body. Element 412 is formed as two concentric metal sleeves, an inner sleeve 420 and an outer sleeve 422. The sleeves are joined at upper 424 and lower 426 ends. Joining is by welding of the sleeves 420,422. Between the sleeves 420,422 is located a filler 428. The filler is entirely contained within the sealing element 412 and bounded on all sides by the metal sleeves 420,422. Thus an interior volume 430 defined by the metal sleeves 420,422 contains an equal volume of the filler 428.

Inner sleeve 420 is geometrically arranged to provide two symmetrical peaks 436a,b running circumferentially around the surface 432. A trough 438 lies between the two peaks 436a,b. Trough 438 has symmetrical sloping side walls with a flat base 439. The outer sleeve 422 has a similar geometrical arrangement on its outer surface 440 to that of the inner surface 432. However peaks 442a,b are somewhat closer together providing a narrower trough 444 without a flat base.

As is seen in FIGS. 7(a) and (b) geometrical arrangement of the sealing element 412 is selected so that when the ends 424,426 are brought together the element 412 will deforms in a controlled manner. The peaks 436,442 and troughs 438,444 act like fold lines on the sleeves 420,422 forming a cantilever structure, which supports the seal. The filler 428 supports the seal 412 to prevent the seal from collapsing with pressure applied from the ends 424. The interior volume 430 and the volume of the filler 428 remain the same during compression of the seal 412. The filler 428 remains in contact with the continuous surface formed by the sleeves 420,422. Delamination does not occur, thus the filler 428 helps prevent the seal 412 collapsing when pressure is applied across the seal.

The principal advantage of the present invention is that by entirely enclosing a filler material within two sleeves, volumetric changes in the sealing element are minimised and the seal will deform in a controlled manner.

A further advantage of an embodiment of the present invention is that it provides a sealing element, which by forming a cantilever structure on deforming, produces a strong seal which can be used to anchor tools in a well bore.

A yet further advantage of an embodiment of the present invention is that it provides a sealing element which does not collapse under pressure differentials. This is done without the need to thicken the sleeves as it is achieved by the ‘rubber pressure’ of the filler within the sealing element.

A still further advantage of an embodiment of the present invention is that it provides a sealing element which does not use elastomers, thus heat and chemicals typically found in well bores will not affect the operation of the seal.

A still further advantage of an embodiment of the present invention is that it provides a sealing element which has the benefits of flexibility, like an elastomer seal, but is fully metal-to metal.

A yet further advantage of at least one embodiment of the present invention is that it provides a sealing element which can be used in dynamic applications where it must slid while maintaining a seal.

It will be appreciated by those in the art that various modifications may be made to the invention hereindescribed without departing from the scope thereof. For example, the overall size of the sealing element can be varied to suit the tool used. The applications describe use in a packer, joint and flange mating but the sealing element could equally be applied to a range of subsea/downhole tools and equipment where a seal and/or anchoring is required.

Claims

1. An annular sealing element (12) for a downhole tool for providing a seal between a first (32) and a second surface, comprising:

an inner sleeve (20) providing an inner deformable surface and arranged concentric with an outer sleeve (22) providing an outer deformable surface, each of the inner and outer sleeves being formed of a material liable to plastic deformation, the inner and outer sleeves being joined at respective junctions of opposed first ends (24) and second ends (26), providing a body defining an interior volume (30) entirely bounded by the said surfaces and said ends, and a deformable filler material (28) within said interior volume, wherein the filler material (28) is a plastic;

wherein the inner and outer sleeves each comprise a plurality of fold lines;

wherein the element (12) deforms in a predetermined manner when said first ends (24) are brought toward said second ends (26) by deformation of the inner and outer sleeves about their respective fold lines, to thereby seal between the first (32) and second surfaces,

wherein the inner and outer sleeves (20, 22) define a first shape containing said interior volume (30), and following deformation the inner and outer sleeves (20, 22) define a second shape, which is a cantilever structure arranged longitudinally between the ends (24, 26), and

wherein the first and second shape shapes are annular having a polygon and are polygonal in longitudinal cross-section.

2. The sealing element (12) of claim 1 wherein the inner and outer sleeves (20, 22) are deformable metal sleeves.

3. The sealing element (12) of claim 1 wherein the polygon is polygonal longitudinal cross section of the first and second shapes are each symmetrical about a horizontal plane, equidistant from the ends (24, 26).

4. The sealing element (12) of claim 1 wherein the deformable filler material (28) has a first volume which equals the interior volume (30) and both remain substantially equal as the ends (24, 26) are brought together.

5. The sealing element (12) of claim 1 wherein the outer surface includes a plurality of outer ridges (68).

6. The sealing element (12) of claim 1 wherein a sealant material is applied to at least a portion of the outer surface.

7. The sealing element (12) of claim 1 wherein at least one metal insert (76) is located in at least a portion of the outer surface.

8. A method of providing a seal between a first (32) and a second surface of a downhole tool, comprising the steps of:

(a) providing the an annular sealing element (12) of claim 1, wherein the element (12) comprises:

an inner sleeve (20) providing an inner deformable surface and arranged concentric with an outer sleeve (22) providing an outer deformable surface, each of the inner and outer sleeves being formed of a material liable to plastic deformation, the inner and outer sleeves being joined at respective junctions of opposed first ends (24) and second ends (26), providing a body defining an interior volume (30) entirely bounded by said surfaces and said ends, and a deformable filler material (28) within said interior volume, wherein the filler material (28) is a plastic;

wherein the inner and outer sleeves each comprise a plurality of fold lines;

wherein the element (12) deforms in a predetermined manner when said first ends (24) are brought toward said second ends (26) by deformation of the inner and outer sleeves about their respective fold lines, to thereby seal between the first (32) and second surfaces,

wherein the inner and outer sleeves (20,22) define a first shape containing said interior volume (30), and following deformation the inner and outer sleeves (20, 22) define a second shape, which is a cantilever structure arranged longitudinally between the ends (24, 26), and

wherein the first and second shapes are annular and are polygonal in longitudinal cross-section;

having a first interior volume (30) and a first shape, and wherein the filler (28) has a first volume substantially equal to the first interior volume;

(b) arranging the element (12) adjacent the first surface (32) and opposite the second surface;

(c) moving one or both ends (24, 26) of the sealing element (12) toward the opposing end (24, 26);

(d) deforming the inner and outer sleeves and the plastic filler material of the sealing element (12) in a controlled manner to provide a the second shape while keeping the first interior volume (30) and the first volume substantially equal, wherein the sealing element (12) forms a the cantilever structure during deformation;

(e) contacting the sealing element (12) on the first (32) and second surfaces to provide the seal; and

(f) further moving one or both ends (24, 26) of the sealing element (12) toward the opposing end (24, 26) to provide a pressure across the sealing element (12) between the inner and outer surfaces (32, 34).

9. The method of claim 8 wherein the method includes the step of deforming the outer and inner sleeves (22, 20) of the sealing element (12).

10. The method of claim 8 wherein the method includes the step of abutting ridges (68) of the sealing element (12) onto at least the second surface (34).

11. The method of claim 8 wherein the method includes the step of abutting a sealing material (72) of the sealing element (12) to at least the second surface (34).

12. The method of claim 8 wherein the method includes the step of abutting a metal insert (76) of the sealing element (12) to at least the second surface (34).

13. A The method as claimed in claim 8, wherein the method is a method of anchoring an apparatus (10) to an inner surface of a well bore and providing a seal between the first (32) and second surfaces, the inner surface of the well bore defining the second surface; and wherein the step of providing the sealing element (12) comprises providing an apparatus (10) including the sealing element (12); and wherein the step of arranging the element (12) adjacent the first surface (32) and opposite the second surface comprises running the apparatus (10) on a work string in the well bore and so arranging the element (12); and further wherein the step of further moving one or both ends (24, 26) of the sealing element (12) toward the opposing end (24, 26) also anchors the apparatus (10) to the second surface.

14. The method of claim 13, wherein the first surface comprises an outer cylindrical surface having a smaller diameter relative to the second surface.

15. The method of claim 8, wherein the first and second surfaces comprise respective opposing outer and inner surfaces of coaxial tubular members.

16. Apparatus An apparatus (10) for providing a seal between a first (32) and a second surface within a well bore, comprising:

a substantially tubular body (16) upon which is located the first surface (32);

a sealing element (12) according to claim 1 located around the tubular body (16);

at least one actuating element (50, 58) arranged around and longitudinally moveable relative to the tubular body (16), the actuating element (50, 58) including means (54, 56; 60, 62) for contacting an end (24, 26) of the sealing element (12);

wherein the sealing element (12) deforms in a predetermined manner to seal between the first and second surfaces (32) when said ends (24, 26) are brought toward each other by movement of the actuating element (50, 58).

17. The apparatus (10) of claim 16 wherein the at least one actuating element (50, 58) is a cone, the cone having a bore therethrough for passage of the tubular body (16).

18. The apparatus (10) of claim 16 wherein the at least one actuating element (50, 58) is a threaded ring.

19. The apparatus as claimed in claim 16, wherein the first surface comprises an outer cylindrical surface and the second surface comprises an opposing inner cylindrical surface.

20. A The sealing element as claimed in claim 1, wherein each of the inner and outer sleeves is rigid.

21. A The sealing element as claimed in claim 1, wherein the ends of the inner and outer sleeves are located in abutment and held together by respective fixing elements.

22. A The sealing element (12) as claimed in claim 1, wherein the inner and outer sleeves (20, 22) contain the deformable filler (28) when said ends of the sleeves are brought toward each other.

23. A The sealing element (12) as claimed in claim 1, wherein the filler (28) is adapted to prevent the sealing element (12) from collapsing under applied pressure.

24. A The sealing element (12) as claimed in claim 1, wherein the inner and outer sleeves are pinched together at the first ends (24) and second ends (26).

25. A The sealing element (12) as claimed in claim 1, wherein the element (12) deforms in a predetermined manner to sealingly contact the first (32) and second surfaces at the respective fold lines of the inner and outer sleeves.

26. A The sealing element (12) as claimed in claim 1, wherein the first and second surfaces comprise respective opposing outer and inner surfaces of coaxial tubular members and wherein the element (12) is disposed longitudinally between the first and second surfaces and deforms in a predetermined manner to sealingly contact the first and second surfaces at the respective fold lines of the inner and outer sleeves.

27. The annular sealing element (12) of claim 1, wherein the inner sleeve (20) comprises at least two troughs and at least one peak an and wherein the inner and outer sleeves are asymmetrical.

28. An annular sealing element (12) for providing a seal between first (32) and second metallic cylindrical surfaces, comprising:

a metallic inner sleeve (20) providing an inner deformable surface, an outer metallic sleeve (22) providing an outer deformable surface, the inner and outer sleeves being joined together at upper and lower junctions at opposite ends of the sleeves to provide a body defining an elongated annular volume (30) entirely bounded by the said surfaces and said junctions, and a deformable plastic filler material (28) within said volume;

wherein the inner and outer sleeves each comprise a plurality of fold lines; and

wherein the element (12) deforms about the fold lines in a predetermined manner when the inner and outer sleeves are compressed at the opposite ends, to thereby form a metal-to-metal seal between the first (32) and second surfaces.