CN112219011A

CN112219011A - Annular barrier

Info

Publication number: CN112219011A
Application number: CN201980037463.6A
Authority: CN
Inventors: R·R·瓦斯克斯
Original assignee: Vertex Oilfield Solutions Jsc
Current assignee: Vertex Oilfield Solutions Jsc; Welltec Oilfield Solutions AG
Priority date: 2018-06-19
Filing date: 2019-06-18
Publication date: 2021-01-12
Also published as: US20190383114A1; WO2019243308A1; EP3584403A1; BR112020024913A2; CA3102446A1; MX2020013143A

Abstract

The present invention relates to an annular barrier for providing zonal isolation within a tubular structure or wellbore and for sealing a first zone from a second zone, comprising: a tubular metal part configured to be mounted as part of a well tubular metal structure, the tubular metal part having an outer surface, an opening and an axial direction along the well tubular metal structure; a first expandable metal sleeve surrounding the tubular metal member and having a first end and a second end connected to an outer surface of the tubular metal member; a second expandable metal sleeve surrounding the tubular metal member and having a first end and a second end connected to an outer surface of the tubular metal member, wherein the first expandable metal sleeve and the second expandable metal sleeve each have an end section at the second end, the end sections of the first expandable metal sleeve and the second expandable metal sleeve at least partially overlapping in the axial direction, thereby forming an overlapping region, the end sections being configured to be slidable relative to each other, the first and second expandable metal sleeves defining, together with the tubular metal part, an annular space extending from the second end of the first expandable metal sleeve in a first direction along the axial direction away from the overlapping region, and the second expandable metal sleeve extends from a second end of the second expandable metal sleeve away from the overlap region in a second direction opposite the first direction.

Description

Annular barrier

Technical Field

The present invention relates to an annular barrier for providing zone isolation inside a tubular structure or wellbore and for sealing a first zone from a second zone, the annular barrier comprising: a tubular metal part configured to be mounted as part of a well tubular metal structure, the tubular metal part having an outer surface, an opening and an axial direction along the well tubular metal structure; a first expandable metal sleeve surrounding the tubular metal member and having a first end connected to the outer surface of the tubular metal member and a second end; and a second expandable metal sleeve surrounding the tubular metal member and having a first end connected to the outer surface of the tubular metal member and a second end.

Background

It is known that annular barriers are limited in how much they can expand radially outwards by the material properties, and many attempts have been made to optimize the material and design of the annular barriers so that they can expand radially outwards more.

Disclosure of Invention

It is an object of the present invention to wholly or partly overcome the above disadvantages and drawbacks of the prior art. More particularly, it is an object to provide an improved annular barrier which is able to expand more radially outwards than known annular barriers without decreasing the collapse rating or similar properties.

The above objects, together with numerous other objects, advantages, and features, which will become evident from the below description, are accomplished by a solution in accordance with the present invention by an annular barrier for providing zonal isolation within a tubular structure or wellbore and for sealing a first zone from a second zone, comprising:

-a tubular metal part configured to be mounted as part of a well tubular metal structure, the tubular metal part having an outer surface, an opening and an axial direction along the well tubular metal structure;

-a first expandable metal sleeve surrounding the tubular metal part and having a first end connected to the outer surface of the tubular metal part and a second end;

-a second expandable metal sleeve surrounding the tubular metal part and having a first end connected to the outer surface of the tubular metal part and a second end; and

-an annular space between the tubular metal part and said expandable metal sleeve,

wherein the first expandable metal sleeve and the second expandable metal sleeve each have an end section at the second end, the end sections of the first expandable metal sleeve and the second expandable metal sleeve at least partially overlapping in the axial direction forming an overlapping region, the end sections configured to be slidable relative to each other, the first expandable metal sleeve extending from the second end of the first expandable metal sleeve away from the overlapping region in a first direction along the axial direction, and the second expandable metal sleeve extending from the second end of the second expandable metal sleeve away from the overlapping region in a second direction opposite the first direction.

By providing the annular barrier with two expandable and overlapping metal sleeves, an annular barrier is obtained which is radially expanded more than known annular barriers.

Furthermore, the end section of the overlap region may not be connected to the outer surface of the tubular metal part.

Furthermore, the annular barrier may comprise a third expandable metal sleeve surrounding the tubular metal part and having a first end connected to the outer surface of the tubular metal part and a second end, an end section of the first end of the second expandable metal sleeve and an end section of the second end of the third expandable metal sleeve at least partially overlapping in said axial direction forming a second overlapping area, such that the second expandable metal sleeve is arranged in between and partially overlapping the first and second expandable metal sleeves. Furthermore, the overlapping area may not be connected to the outer surface of the tubular metal part.

Furthermore, the annular space may be in fluid connection with the opening.

Furthermore, the material of the expandable metal sleeve in the overlap region may be less ductile than the material of the rest of the expandable metal sleeve.

Furthermore, the end sections of the overlapping area may have a common thickness which is greater than the thickness of the rest of the expandable metal sleeve.

Furthermore, at least one sealing element may be arranged between the end sections of the overlap region.

Furthermore, at least one sealing element may be arranged in a groove on one of the end sections of the expandable metal sleeve.

Furthermore, an end section of the first expandable metal sleeve may be arranged to be slidable along an outer surface of the second expandable metal sleeve, the end of the second sleeve providing a piston action during expansion, providing a pressure force to the end of the second expandable metal sleeve in the axial direction.

Furthermore, an end section of the second end of the second expandable metal sleeve may be arranged to be slidable along an inner surface of the first expandable metal sleeve and an end section of the first end of the second expandable metal sleeve may be arranged to be slidable along an inner surface of the third expandable metal sleeve.

Furthermore, the second expandable metal sleeve may have a varying thickness.

Further, the second expandable metal sleeve may have an intermediate section between the first and second ends, which may have a thickness that is less than the thickness at the first and second ends.

Furthermore, the second expandable metal sleeve may have a cross-section that is curved in the axial extension of the annular barrier.

Furthermore, the overlap region may remain substantially unexpanded during expansion of the remainder of the expandable metal sleeve.

Furthermore, each expandable metal sleeve may be comprised of a first section and a second section, the second section being the end section and the first section being the remainder of the expandable metal sleeve.

Further, the first section may have an unexpanded state and an expanded state, the first section being capable of expanding more than 30% as compared to the unexpanded state.

The end sections of each sleeve have a length in the unexpanded state of at least 5% of the total length of the expandable metal sleeve.

Furthermore, the end section of the first expandable metal sleeve may have grooves corresponding to the grooves on the outer surface of the end section of the second expandable metal sleeve, forming a ratchet-type system capable of preventing the end section of the first expandable metal sleeve from returning after the end section of the first expandable metal sleeve has moved away from the end section of the second expandable metal sleeve.

The annular barrier according to the invention may further comprise a shear pin assembly fluidly connecting the expansion opening with the annular space for allowing an expansion fluid inside the well tubular structure to expand the expandable metal sleeve.

Further, the shear pin assembly may have a first position in which expansion fluid is allowed to flow into the annular space and a second position in which the expansion opening is blocked, thereby preventing expansion fluid from entering the annular space.

Furthermore, fluid from the inside of the tubular metal part may enter the expansion unit via the opening and further into the annular space.

The annular barrier according to the invention may further comprise an anti-collapse unit comprising an element movable between at least a first position and a second position, the anti-collapse unit having a first inlet in fluid communication with the first region and a second inlet in fluid communication with the second region, and the anti-collapse unit having an outlet in fluid communication with the annular space, and in the first position the first inlet is in fluid communication with the outlet, thereby equalizing a first pressure of the first region with the space pressure, and in the second position the second inlet is in fluid communication with the outlet, thereby equalizing a second pressure of the second region with the space pressure.

The anti-collapse unit may be fluidly connected to the opening or the expansion unit.

The annular barrier according to the invention may further comprise a sealing element arranged on the outer surface of the expandable metal sleeve.

Furthermore, the sealing element may be arranged in a groove on the outer surface of the expandable metal sleeve.

Furthermore, a sealing element and a split ring-shaped retaining element may be arranged in the groove, which split ring-shaped retaining element forms a stop/support for the sealing element.

Furthermore, the split ring-shaped retaining element may have more than one winding, such that the split ring-shaped retaining element is partially unwound/deployed when the expandable tubular is expanded from a first outer diameter to a second outer diameter which is larger than the first outer diameter.

Furthermore, an intermediate element may be arranged between the split ring-shaped holding element and the sealing element.

Further, the first end of the expandable metal sleeve may be welded to the outer surface of the tubular metal member.

Finally, the annular barrier according to the invention may further comprise a first connecting part connecting the first end of the first expandable metal sleeve to the outer surface of the tubular metal part and a second connecting part connecting the first end of the second expandable metal sleeve to the outer surface of the tubular metal part.

Drawings

The invention and many of its advantages will be described in more detail below with reference to the accompanying schematic drawings, which show, for purposes of illustration, only some non-limiting embodiments, in which:

fig. 1A shows a cross-sectional view of an annular barrier in an unexpanded state;

FIG. 1B shows a cross-sectional view of the annular barrier of FIG. 1A in its expanded state isolating a first zone from a second zone;

fig. 2A shows a cross-sectional view of another annular barrier in its unexpanded state;

FIG. 2B shows a cross-sectional view of the annular barrier of FIG. 2B in a partially expanded intermediate state during expansion thereof;

fig. 2C shows a cross-sectional view of the annular barrier of fig. 2B in its expanded state;

fig. 3 shows a cross-sectional view of another annular barrier in its unexpanded state;

FIG. 4 shows a perspective view of another annular barrier with a shear pin assembly and an anti-collapse unit;

fig. 5A and 5B show cross-sectional views of a portion of another annular barrier having a shear pin assembly, in fig. 5A the shear pin assembly being shown in a first position, and in fig. 5B the shear pin assembly being shown in its closed second position;

FIG. 6 shows a cross-sectional view of an anti-collapse unit;

fig. 7 shows a cross-sectional view of another annular barrier in its unexpanded state; and

fig. 8 shows a cross-sectional view of a further annular barrier in its unexpanded state.

All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary for the elucidation of the invention, other parts being omitted or merely suggested.

Detailed Description

Fig. 1A shows an annular barrier 1 for providing zonal isolation within a wellbore 2 and for sealing a first zone 101 from a second zone 101, as shown in fig. 1B. The annular barrier comprises a tubular metal part 7 configured to be mounted as part of the well tubular metal structure 3. The tubular metal part 7 has an outer surface 4 and at least one opening 16 through which a fluid can pass to expand the annular barrier. The tubular metal part has an axial direction L substantially coinciding with the well tubular metal structure. The annular barrier further comprises a first expandable metal sleeve 6 surrounding the tubular metal part and having two ends, a second end 10 and a first end 9 connected to the outer surface of the tubular metal part. The annular barrier 1 further comprises a second expandable metal sleeve 8 surrounding the tubular metal part 7 and having a first end 12 connected to the outer surface 4 of the tubular metal part and a second end 14. The first expandable metal sleeve 6 has an

end section

21,21A at its second end 10 and the second expandable metal sleeve 8 has an

end section

21,21B at its second end 14. The

end sections

21,21A of the first expandable metal sleeve and the

end sections

21,21B of the second expandable metal sleeve partially overlap in said axial direction, thereby forming an overlap region 31. The

end sections

21A,21B are configured to slide relative to each other and the first expandable metal sleeve 6 and the second expandable metal sleeve 8 together with the tubular metal part define an annular space 15. The first expandable metal sleeve 6 extends from its second end away from the overlap region in a first direction along the axial direction, and the second expandable metal sleeve 8 extends from its second end 21B away from the overlap region in a second direction opposite to the first direction.

By providing the annular barrier 1 with two expandable and partially overlapping metal sleeves, an annular barrier is obtained which is radially expanded more than known annular barriers. Annular barriers are known having a metal sleeve which tapers during expansion and this tapering defines the maximum radial expansion, since the sleeve is to withstand a predetermined collapse pressure after expansion and, therefore, cannot expand to an extent that is not able to withstand the collapse pressure. By having two overlapping sleeves, the sleeves slide away from each other during expansion and thinning is minimized, and thus the annular barrier of the present invention may expand further radially outward than an annular barrier having sleeves of the same material condition and thickness.

The

end sections

21,21A of the first expandable metal sleeve and the

end sections

21,21B of the second expandable metal sleeve partially overlap in the axial direction, forming an overlap region 31 along the entire circumference of the annular barrier.

In fig. 1A, the annular barrier is shown in its unexpanded position, and each expandable metal sleeve has a first section 41 and a second section 42. The second section is an

end section

21,21A,21B and the first section is the rest of the expandable metal sleeve, whereby the first expandable metal sleeve 6 has a first section 41 and a second section 42 being its end section 21A and the second expandable metal sleeve 8 has in axial direction a first section 41 and a second section 42 being its end section 21B. In fig. 1B, fluid from the interior 23 of the tubular metal part 7 has entered the opening 16 and further into the annular space 15, and the first section of the sleeve is expanded until it abuts the wall 24 of the wellbore 2.

As can be seen from fig. 1A and 1B, in both the unexpanded state shown in fig. 1A and the expanded state shown in fig. 1B, the

end sections

21A,21B of the overlap region 31 are not connected to the outer surface 4 of the tubular metal part 7. Thus, the overlap region 31 is not connected to the outer surface 4 of the tubular metal part 7.

In one embodiment, the material of the

expandable metal sleeve

6, 8 in the overlap region 31 is less ductile than the material of the rest of the expandable metal sleeve, such that when setting the annular barrier 1, a first section 41 of the expandable metal sleeve is expanded while a second section remains substantially unexpanded.

In another embodiment, the

end sections

21,21A,21B of the overlapping area have a larger thickness than the rest of the expandable metal sleeve, such that when setting the annular barrier 1, a first section of the expandable metal sleeve is expanded while a second section remains substantially unexpanded. Thus, the material of the

expandable metal sleeves

6, 8 in the overlap region 31 may be hardened, for example by heat treatment and/or deformation hardening.

Furthermore, the material of the

expandable metal sleeve

6, 8 in the overlap region 31 may be different from the material of the rest of the

expandable metal sleeve

6, 8 and welded together, so that the first section is made of a different material than the second section.

In fig. 1A and 1B, a sealing element 29 is arranged between the end sections of the overlap region. Each sealing element 29 is arranged in a groove 30 on one of the end sections of the expandable metal sleeve. The end section 21A of the first expandable metal sleeve 6 is arranged to be slidable along the outer surface 32 of the second expandable metal sleeve, so that the end of the second expandable metal sleeve extends into the annular space 15 and provides the effect of a piston during expansion, i.e. providing pressure to the end of the second expandable metal sleeve in the axial direction. The first section has an unexpanded state as shown in fig. 1A and an expanded state as shown in fig. 1B, and the first section is capable of expanding more than 30% as compared to the unexpanded state.

The end section 21 of each sleeve has a length L1 in the unexpanded state, which length L1 is at least 5% of the total length L2 of the expandable metal sleeve in the unexpanded state. The length of the end section of the first expandable metal sleeve may be different from the length of the end section of the second expandable metal sleeve.

Fig. 2A-2C show an annular barrier 1 which provides zone isolation within a tubular structure 3A, thereby sealing a first zone from a second zone. In fig. 2A, the annular barrier is shown in its unexpanded state, which is an initial position of the annular barrier when lowering the well tubular metal structure into the well. The first ends 9, 12 of the

expandable metal sleeves

6, 8 are welded to the outer surface 4 of the tubular metal part 7. In another embodiment the annular barrier comprises a connecting part connecting the first end to the tubular part and in fig. 1A and 1B the distance/spacer ring 51 is arranged below the sleeve at the first end and welded to the tubular metal part.

In fig. 1A-1B, the first expandable metal sleeve is cast and machined as a single piece, and the second expandable metal sleeve is likewise a single piece and is not mounted or welded from multiple pieces. Thus, the first section 41 and the second section 42 of each expandable metal sleeve are made in one piece. However, in fig. 2A-2C, the second section of the first expandable metal sleeve is welded to the first section of the first expandable metal sleeve by means of the connecting element 52, and thus the first expandable metal sleeve is mounted and welded from three pieces. The second section of the second expandable metal sleeve is welded to the first section of the second expandable metal sleeve and the retaining ring 53 is mounted on the connection. Fig. 2B shows the annular barrier during expansion, and fig. 2C discloses the annular barrier fully expanded. In fig. 2C, the connecting element 52 is slightly expanded and acts as a retaining ring like the retaining ring 53, which retaining ring 53 is also slightly expanded. However, the second section remains substantially unexpanded. After expansion, the sealing element 28 provides the sealing capability of the annular barrier against the tubular structure 3A and the confined space 54 provided between the expanded first section, second region and tubular structure is not subjected to any substantial pressure and is not resistant to the predetermined collapse pressure. Therefore, the overlapping section does not withstand high pressures.

In fig. 3, the end section of the first expandable metal sleeve has grooves 33 corresponding to the grooves 34 on the outer surface 32 of the end section of the second expandable metal sleeve, forming a ratchet-type system 35 that can prevent the end section of the first expandable metal sleeve from returning after it has moved away from the end section of the second expandable metal sleeve.

In figure 4, the annular barrier 1 further comprises a shear pin assembly 37 fluidly connecting the opening with the annular space for allowing an expansion fluid within the well tubular structure 3 to expand the

expandable metal sleeves

6, 8. Shear pin assembly 37 has a first position (shown in fig. 5A) in which expansion fluid is allowed to flow into annular space 15, and a second position (shown in fig. 5B) in which opening 16 is blocked, thereby preventing expansion fluid from entering annular space 15. As shown in fig. 4, the annular barrier further comprises an anti-collapse unit 11 comprising an element 20, such as a sphere shown in fig. 6, movable at least between a first position and a second position, the anti-collapse unit having a first inlet 25 in fluid communication with the first region and a second inlet 26 in fluid communication with the second region, and the anti-collapse unit having an outlet 27 in fluid communication with the annular space, and in the first position the first inlet is in fluid communication with the outlet, thereby equalizing the pressure of the first region 101 with the space pressure in the annular space, and in the second position the second inlet is in fluid communication with the outlet, thereby equalizing the pressure of the second region with the space pressure.

As shown in fig. 4, the annular barrier 1 further comprises a shear pin assembly 37. The shear pin assembly 37 has a port a for receiving fluid from the interior of the well tubular structure 3 via a screen 44. The port a is fluidly connected with the port D during expansion, so that an expansion fluid inside the well tubular structure can expand the

expandable sleeves

6, 8. When the

expandable sleeves

6, 8 expand against the wall of the tubular structure, pressure builds and the shear pins or discs within the shear pin assembly shear, closing the fluid connection between port a and opening 16 (shown in fig. 5B) and opening the fluid connection between port B (in fluid communication with outlet 27) and port C (in fluid communication with annular space 15), so that fluid from the second inlet 26 can be allowed to enter the annular space 15 via the shear pin assembly. When the first pressure in the first zone increases, fluid from port E, which is connected to port I (being the first inlet 25), pushes the element 20 (shown in fig. 6) to move, providing fluid communication between port I and port H (being the outlet) and thus further through ports B and C and into the annular space via port D. When the second pressure in the second region increases, the element is forced in the opposite direction and fluid communication is provided between port G (in fluid communication with the second region via port F) and port H, i.e. between the outlet 27 of the anti-collapse unit 11 and the second inlet 26, and thus fluid is allowed to enter the annular space via ports B, C and D.

The shear pin assembly shown in fig. 5A and 5B includes a first bore section 19 having a first inner diameter and a second bore section 120 having an inner diameter greater than the inner diameter of the first bore section. The opening 16 and the second opening 17 are arranged in this first bore portion 19 and are displaced/staggered in the direction of bore extension. The annular barrier 1 further comprises a piston 121 arranged in the inner bore 18, the piston comprising a first piston part 22 having an outer diameter substantially corresponding to the inner diameter of the first inner bore part 19, and the piston comprising a second piston part 23B having an outer diameter substantially corresponding to the inner diameter of the second inner bore part 120. The annular barrier 1 further comprises a rupture element 24B for preventing the piston 121 from moving until a predetermined pressure is reached in the inner bore 18. The strength of the rupture element is set based on a predetermined pressure acting on the area of the end of the piston and therefore the difference in outer diameter causes the piston to move when the pressure exceeds the predetermined pressure. The piston 121 includes a fluid passageway 125 that is a through bore that provides fluid communication between the first and

second bore portions

19, 120.

In fig. 5A and 5B, the rupture element 24B is a shear pin, but may also be a disc. In fig. 5A the shear pin is intact and extends through the piston and insert 43, and in fig. 5B the shear pin has been sheared, and the piston is allowed to move and the insert 43 has moved towards the centre of the bore 18. Depending on the isolation scheme required to provide downhole isolation, the fracture element 24B is selected based on the expansion pressure so that the fracture element can fracture at pressures above the expansion pressure but below a pressure that would rupture the expandable metal sleeve or otherwise compromise the function of other completion components downhole. The bore 18 and the piston 121 may be arranged in a connecting part connecting the first end to the tubular metal part.

In fig. 5A, the annular barrier 1 comprises a locking element 38 arranged around the second piston part 23B. The bore further includes a third opening 137 in the second bore portion 120 that is in fluid communication with the annular space 15 and the annulus/bore 2. The third opening 137 may be arranged in fluid communication with a reversing valve (i.e. the anti-collapse unit 11) (as shown in fig. 6) such that the reversing valve is arranged between the third opening and the annulus, thus providing fluid communication between the annular space and the annulus. The directional valve provides fluid communication between the annular space and a first region 101 of the annulus in the first position and provides fluid communication between the annular space and a second region 102 of the annulus (shown in fig. 1B) in the second position.

As shown in fig. 1A, the annular space further comprises a sealing element 28 arranged on the

outer surface

32,36 of the expandable metal sleeve. The sealing element 28 may be disposed in a groove 48 located on the outer surface of the expandable metal sleeve. A split ring-shaped retaining element 47 is arranged in the groove 48 between the first and second circumferential edges and forms a stop/support for the sealing element. Each split annular retaining element 47 has more than one winding so that the split annular retaining element 47 can be partially unwound when the expandable metal sleeve is expanded from a first outer diameter to a second outer diameter that is larger than the first outer diameter. An intermediate element 49 is arranged between the split ring-shaped holding element 47 and the sealing element 28. In fig. 1A, a groove is provided between two protrusions 50.

As in fig. 5A and 5B, the annular barrier 1 further comprises a first connecting part (not shown) connecting the first end of the first expandable metal sleeve to the outer surface of the tubular metal part and a second connecting part 45 connecting the first end of the second expandable metal sleeve to the outer surface of the tubular metal part.

In fig. 7, a cross-sectional view of another annular barrier in an unexpanded state is shown. The annular barrier comprises two connection rings 56, one connection ring 56 connecting the first end 9 of the first expandable metal sleeve 6 and the other connection ring 56 connecting the first end 12 of the second expandable metal sleeve 8. The connecting ring 56 overlaps the first end and reduces free expansion of the first end. The connection ring 56 is welded to the tubular metal part 7 and the connection ring 56 is also welded to the expandable metal sleeve. Each expandable metal sleeve has a first section 41 and a second section 42. The second section is an

end section

21,21A,21B and the first section is the rest of the expandable metal sleeve. In fig. 7, the second section 42 of the first expandable metal sleeve 6 is the innermost second section in the overlap region 31, and in fig. 1A, the second section 42 of the first expandable metal sleeve 6 is the outermost second section in the overlap region 31.

As shown in fig. 8, the annular barrier comprises a third expandable metal sleeve 55, which surrounds the tubular metal part. The third expandable metal sleeve has a first end 56 connected to the outer surface of the tubular metal part and a second end 57 facing the second expandable metal sleeve, such that an end section 58 of the first end 12 of the second expandable metal sleeve 8 and an end section 59 of the second end of the third expandable metal sleeve partially overlap in axial direction, forming a second overlap region 31B. Thus, the second expandable metal sleeve is arranged intermediate the first expandable metal sleeve and the third expandable metal sleeve, such that an end section of the second expandable metal sleeve partially overlaps the first and third expandable metal sleeves, and such that the first, second and third expandable metal sleeves are arranged in sequence, but partially overlapping in axial direction, thereby forming one common sleeve. The first expandable metal sleeve is connected at a first end to the tubular metal member and slidably connected at another end to the second expandable metal sleeve. One end of the third expandable metal sleeve is connected to the tubular metal member and the other end is slidably connected to the second expandable metal sleeve. The second expandable metal sleeve is thus connected with the tubular metal part via the first and third expandable metal sleeves and the inner surface of at least the end of the second expandable metal sleeve abuts against the outer surface of the tubular metal part in its unexpanded state. The end section 59 of the second end of the third expandable metal sleeve overlaps the end section 58 of the first end 12 of the second expandable metal sleeve 8 and the end section of the second end 10 of the first expandable metal sleeve 6 overlaps the end section of the second end 14 of the second expandable metal sleeve 8. The second expandable metal sleeve is thus held in place by the overlapping ends of the first and third expandable metal sleeves during insertion of the annular barrier into the well. During expansion of the annular barrier, the second expandable metal sleeve expands radially with the overlapping ends of the first and third expandable metal sleeves. During expansion, the end of the second expandable metal sleeve slides relative to the end of the first expandable metal sleeve and the end of the third expandable metal sleeve. During radial expansion of the second expandable metal sleeve, the second expandable metal sleeve is not inhibited in terms of its reduction in length, since the second expandable metal sleeve is not fastened to the tubular metal part, and thus the second expandable metal sleeve is thinned less than if one end of the second expandable metal sleeve were fastened to the tubular metal part, since this end would become thinner if it were fastened to the well metal structure.

The

end sections

21,21A of the first expandable metal sleeve and the

end sections

21,21B of the second expandable metal sleeve partially overlap in the axial direction, forming an overlap region 31 along the entire circumference of the annular barrier. In the same way, the end section 59 of the third expandable metal sleeve and the end section 58 of the second expandable metal sleeve partially overlap in the axial direction, forming an overlap region 31B in the entire circumference of the annular barrier.

The end section of the second end 14 of the second expandable metal sleeve is arranged to be slidable along the inner surface 61 of the first expandable metal sleeve and the end section of the first end 12 of the second expandable metal sleeve is arranged to be slidable along the inner surface 62 of the third expandable metal sleeve. A sealing element is provided in the outer surface of the second expandable metal sleeve, sealing against the

inner surfaces

61 and 62. Thus, the annular barrier of fig. 8 has two overlapping

areas

31 and 31B with a sealing element arranged therebetween. An annular space 15 is defined by the first, second and third expandable metal sleeves and the tubular metal part 7.

As can be seen in fig. 8, the second end 10 of the first expandable metal sleeve 6 and the second end 57 of the third expandable metal sleeve taper in thickness in a direction towards their ends so as to be greatest in thickness in their unexpanded state shown in fig. 8 at a location opposite the sealing element in the outer surface of the second expandable metal sleeve. The end sections of the overlapping area have a common thickness which is greater than the thickness of the rest of the second expandable metal sleeve.

The second expandable metal sleeve may have a slightly smaller thickness intermediate its first and second end portions, as seen in a cross-section in the axial direction of the annular barrier, so that expansion initially takes place at an intermediate portion of the second expandable metal sleeve which does not overlap the end portions of the first and third expandable metal sleeve.

The first end of the first expandable metal sleeve and the first end of the third expandable metal sleeve are fastened to the tubular metal part, for example by means of welding or similar fastening means. One of the first end of the first expandable metal sleeve and the first end of the third expandable metal sleeve may also be slidably connected to the tubular metal member.

The annular barrier may be expanded by pressurising the well tubular metal structure from the surface or by pressurising the well tubular metal structure from the surface by means of a drill pipe connecting the well tubular metal structure to the surface. The annular barrier may also be expanded by means of a tool that isolates the section facing the opening 16.

Fluid or wellbore fluid refers to any type of fluid present downhole in an oil or gas well, such as natural gas, oil-based mud, crude oil, water, and the like. Gas refers to any type of gas component present in a well, completion, or open hole, and oil refers to any type of oil component, such as crude oil, oleaginous fluids, and the like. The gas, oil and water fluids may thus each comprise other elements or substances than gas, oil and/or water, respectively.

By a casing, tubular structure or well tubular metal structure is meant any type of pipe, tubing, tubular structure, liner, string etc. used downhole in connection with oil or gas production.

In the event that the tool is not fully submerged in the casing, a downhole tractor may be used to push the tool fully into position in the well. The downhole tractor may have projectable arms with wheels, wherein the wheels contact an inner surface of the casing for advancing the tractor and the tool within the casing. Downhole tractors are any type of driving tool capable of pushing or pulling a tool downhole, e.g. Well

Although the invention has been described above in connection with preferred embodiments thereof, several variations will be apparent to those skilled in the art which may be made without departing from the invention as defined in the following claims.

Claims

1. An annular barrier (1) for providing zone isolation within a tubular structure (3A) or wellbore (2) and for sealing a first zone (101) from a second zone (101), the annular barrier comprising:

-a tubular metal part (7) configured to be mounted as part of a well tubular metal structure (3), the tubular metal part having an outer surface (4), an opening (16) and an axial direction (L) along the well tubular metal structure;

-a first expandable metal sleeve (6) surrounding the tubular metal part and having a first end (9) connected to the outer surface of the tubular metal part and a second end (10);

-a second expandable metal sleeve (8) surrounding the tubular metal part and having a first end (12) connected to the outer surface of the tubular metal part and a second end (14); and

-an annular space (15) between the tubular metal part and said expandable metal sleeve,

wherein the first and second expandable metal sleeves each have an end section (21) at the second end, the end sections of the first and second expandable metal sleeves at least partially overlapping in the axial direction forming an overlapping region (31), the end sections being configured to be slidable relative to each other, the first expandable metal sleeve extending from the second end of the first expandable metal sleeve away from the overlapping region in a first direction along the axial direction, the second expandable metal sleeve extending from the second end of the second expandable metal sleeve away from the overlapping region in a second direction opposite the first direction.

2. An annular barrier according to claim 1, wherein the end sections of the overlap area are not connected to the outer surface of the tubular metal part.

3. An annular barrier according to claim 1 or 2, further comprising a third expandable metal sleeve (55) surrounding the tubular metal part and having a first end (56) connected to the outer surface of the tubular metal part and a second end (57), an end section (58) of the first end (12) of the second expandable metal sleeve (8) and an end section (59) of the second end of the third expandable metal sleeve at least partially overlapping in the axial direction forming a second overlapping area (31B).

4. An annular barrier according to any of the preceding claims, wherein the end sections of the overlap area have a common thickness which is larger than the thickness of the rest of the expandable metal sleeve.

5. An annular barrier according to any of the preceding claims, wherein at least one sealing element (29) is arranged between end sections of the overlap area.

6. An annular barrier according to any of the preceding claims, wherein an end section of the first expandable metal sleeve is arranged slidable along an outer surface (32) of the second expandable metal sleeve, the end of the second expandable metal sleeve providing a piston action during expansion, providing a pressure force to the end of the second expandable metal sleeve in the axial direction.

7. An annular barrier according to any of the preceding claims, wherein an end section of the second end of the second expandable metal sleeve is arranged to be slidable along an inner surface (61) of the first expandable metal sleeve and an end section of the first end of the second expandable metal sleeve is arranged to be slidable along an inner surface (62) of the third expandable metal sleeve.

8. An annular barrier according to any of the preceding claims, wherein the overlap area remains substantially unexpanded during expansion of the rest of the expandable metal sleeve.

9. An annular barrier according to any of the preceding claims, wherein each expandable metal sleeve is constituted by a first section (41) and a second section (102), the second section being the end section.

10. An annular barrier according to claim 8, wherein the first section has an unexpanded state and an expanded state, the first section being expandable by more than 30% compared to the unexpanded state.

11. An annular barrier according to any of the preceding claims, wherein the end section of each sleeve in the unexpanded state has a length (L1) of at least 5% of the total length (L2) of the expandable metal sleeve.

12. An annular barrier according to any of the preceding claims, wherein the end section of the first expandable metal sleeve has grooves (33) corresponding to grooves (34) on the outer surface of the end section of the second expandable metal sleeve, forming a ratchet-type system (35) capable of preventing the end section of the first expandable metal sleeve from returning after the end section of the first expandable metal sleeve has moved away from the end section of the second expandable metal sleeve.

13. An annular barrier according to any of the preceding claims, further comprising a shear pin assembly (37) fluidly connecting an expansion opening with the annular space for allowing an expansion fluid inside the well tubular structure to expand the expandable metal sleeve.

14. An annular barrier according to any of the preceding claims, further comprising an anti-collapse unit (11) comprising an element (20) like a sphere movable at least between a first position and a second position, the anti-collapse unit having a first inlet (25) in fluid communication with the first region and a second inlet (26) in fluid communication with the second region, and the anti-collapse unit having an outlet (27) in fluid communication with the annular space, in the first position the first inlet being in fluid communication with the outlet, thereby equalizing the first pressure of the first region with a spatial pressure, and in the second position the second inlet being in fluid communication with the outlet, thereby equalizing the second pressure of the second region with the spatial pressure.

15. An annular barrier according to any of the preceding claims, further comprising a sealing element (28) arranged on an outer surface (32,36) of the expandable metal sleeve.

16. An annular barrier according to any of the preceding claims, wherein the first end of the expandable metal sleeve is welded to the outer surface of the tubular metal part.