AU2013100385A4 - Annular barrier - Google Patents

Abstract

The present invention relates to an annular barrier (1) arranged in a borehole (100) for providing zone isolation between a first zone (102) and a second zone (103) of the borehole, the annular barrier having an axial extension, comprising a tubular part (2) for mounting as part of a well tubular structure or casing (300) and having an expansion opening (9), an expandable sleeve (3) surrounding the tubular part, each end (31, 32) of the expandable sleeve being connected with the tubular part, the expandable sleeve having a sleeve length (ls)and extending along the axial extension, the expandable sleeve having a middle point (Pm) which is positioned at half the sleeve length from the ends, an annular barrier space (30) between the tubular part (2) and the expandable sleeve (3), wherein a first diaphragm (4) arranged in the annular barrier space divides the annular barrier space into a barrier compartment (7) and an expansion compartment (6), and wherein the expansion compartment (6) is in fluid communication with an inside (302) of the tubular part (2) through the expansion opening (9), and the barrier compartment (7) is in fluid communication with the borehole (100) through a first barrier opening (10), and wherein each end of the expandable sleeve and the first diaphragm are fastened to the tubular part by means of a separate connection part without welding, the connection part being tubular and arranged concentrically to the tubular part, and the connection part having a length which is less than 50% of the sleeve length, the first barrier opening being arranged closer to one of the connection parts than the middle point of the expandable sleeve.

Description

1 ANNULAR BARRIER Field of the invention [0001] The present invention relates to an annular barrier arranged in a borehole for providing zone isolation between a first zone and a second zone. Background art [0002] In wellbores, annular barriers are used for different purposes, such as for providing an isolation barrier. An annular barrier has a tubular part mounted as part of the well tubular structure, such as the production casing, which is surrounded by an annular expandable sleeve. The expandable sleeve is typically made of an elastomeric material, but may also be made of metal. The sleeve is fastened at its ends to the tubular part of the annular barrier. [0003] In order to seal off a zone between a well tubular structure and the borehole or an inner and an outer tubular structure, a second annular barrier is used. The first annular barrier is expanded on one side of the zone to be sealed off, and the second annular barrier is expanded on the other side of that zone, and in this way, the zone is sealed off. [0004] The pressure envelope of a well is governed by the burst rating of the tubular and the well hardware etc. used within the well construction. In some circumstances, the expandable sleeve of an annular barrier may be expanded by increasing the pressure within the well, which is the most cost-efficient way of expanding the sleeve. The burst rating of a well defines the maximum pressure that can be applied to the well for expanding the sleeve, and it is desirable to minimise the expansion pressure required for expanding the sleeve in order to minimise the exposure of the well to the expansion pressure. [0005] When expanded, annular barriers may be subjected to a continuous pressure or a periodic high pressure from the outside, either in the form of hydraulic pressure within the well environment or in the form of formation pressure. In some circumstances, such pressure may cause the annular barrier to collapse, which may have severe consequences for the area which is to be sealed off by the barrier, as the sealing properties are lost due to the collapse. A similar problem may arise when the expandable sleeve is expanded by expansion means, e.g. a pressurised fluid. If the fluid leaks from the sleeve, the back pressure may fade, and the sleeve itself may thus collapse.

2 [0006] The ability of the expanded sleeve of an annular barrier to withstand the collapse pressure is thus affected by many variables, such as strength of material, wall thickness, surface area exposed to the collapse pressure, temperature, well fluids, etc. [0007] A collapse rating currently achievable for the expanded sleeve within certain well environments is insufficient for all well applications. Thus, it is desirable to increase the collapse rating to enable annular barriers to be used in all wells, specifically in wells with a high drawdown pressure during production and depletion. The collapse rating may be increased by increasing the wall thickness or the strength of the material; however, this would increase the expansion pressure, which, as already mentioned, is not desirable. [0008] It is thus desirable to provide a solution wherein the annular barrier is improved so that it does not collapse, without having to increase the thickness of the expandable sleeve. Summary of the invention [0009] It is an object of the present invention to wholly or at least partly overcome at least one of the above disadvantages and drawbacks of the prior art. [0010] The present invention relates to an annular barrier arranged in a borehole for providing zone isolation between a first zone and a second zone of the borehole, the annular barrier having an axial extension, comprising: - a tubular part for mounting as part of a well tubular structure or casing and having an expansion opening, - an expandable sleeve surrounding the tubular part, each end of the expandable sleeve being connected with the tubular part, the expandable sleeve having a sleeve length and extending along the axial extension, the expandable sleeve having a middle point which is positioned at half the sleeve length from the ends, - an annular barrier space between the tubular part and the expandable sleeve, wherein a first diaphragm arranged in the annular barrier space divides the annular barrier space into a barrier compartment and an expansion compartment, and wherein the expansion compartment is in fluid communication with an inside of the tubular part through the expansion opening, and the barrier compartment is in fluid communication with the borehole through a first barrier opening and 3 wherein each end of the expandable sleeve and the first diaphragm are fastened to the tubular part by means of a separate connection part without welding, the connection part being tubular and arranged concentrically to the tubular part, and the connection part having a length which is less than 50% of the sleeve length, the first barrier opening being arranged closer to one of the connection parts than the middle point of the expandable sleeve. [0011] By having a diaphragm, the annular barrier, in accordance with at least a preferred embodiment, is capable of withstanding an outside pressure that is higher than the pressure in the well tubular structure without changing the pressure inside the well tubular structure since the diaphragm seals off the inside of the well tubular structure from the outside of the well tubular structure. By having the first barrier opening being arranged closer to one of the connection parts than the middle point of the expandable sleeve, in accordance with at least a preferred embodiment, the opening is not blocked by the inner wall of the borehole when the expandable sleeve is expanded and part of the sleeve abuts the borehole. Furthermore, each end of the expandable sleeve and the first diaphragm are fastened to the tubular part by means of a separate connection part without welding. When using a welded connection, harm may be done to the material of the expandable sleeve, the connection part and/or the tubular part, and therefore by having the connection part squeezed or otherwise fitted onto the tubular part fastening the sleeve, in accordance with at least a preferred embodiment, the sleeve is not damaged. The connection part has a length which is at least 10% and less than 50% of the sleeve length, the connection part, at least in accordance with a preferred embodiment, being able to hold the expandable sleeve and the diaphragm fixed to the tubular part, also during expansion. [0012] In an embodiment, each end of the expandable sleeve and the first diaphragm may be fastened to the tubular part by means of crimping, gluing, pressing, heating or cooling. [0013] Moreover, the annular barrier may further comprise at least one sealing element arranged in grooves in a first part of the connection part and facing the tubular part. [0014] Also, the connection part may have a second part overlapping one end of the expandable sleeve and the first diaphragm for pressing the end of the expandable sleeve and the first diaphragm towards the tubular part. [0015] Furthermore, the annular barrier may comprise a sealing element arranged on an outer face of the expandable sleeve for sealing against the inside of the borehole, the sealing element 4 having an uneven thickness along the axial extension, the sealing element covering at least 50% of the sleeve length. Brief Description of the Drawings [0016] Non-limiting embodiments of the present invention will now be described, by way of example only, with reference to the accompanying schematic drawings wherein: [0017] Fig. 1 shows a cross-sectional view along a longitudinal extension of an annular barrier in its unexpanded condition, [0018] Fig. 2 shows the annular barrier of Fig. 1 in its expanded condition, [0019] Fig. 3 shows the annular barrier of Fig. 2 in a situation where a first zone pressure has exceeded a pressure inside the well tubular structure, [0020] Fig. 4 shows the annular barrier of Fig. 1 in an intermediate situation, [0021] Fig. 5 shows an annular barrier having two diaphragms in its unexpanded condition, [0022] Fig. 6 shows the annular barrier of Fig. 5 in its expanded condition, [0023] Fig. 7 shows the annular barrier of Fig. 5 in a situation where a first zone pressure has exceeded a pressure inside the well tubular structure, [0024] Fig. 8 shows the annular barrier of Fig. 5 in a situation where a second zone pressure has exceeded a pressure inside of the well tubular structure, [0025] Fig. 9 shows the annular barrier of Fig. 5 in an intermediate situation, [0026] Fig. 1OA shows another embodiment of the annular barrier having two diaphragms in its expanded condition, [0027] Fig. 1OB shows yet another embodiment of the annular barrier having two diaphragms in its expanded condition, 5 [0028] Fig. 11 shows yet another embodiment of the annular barrier having two diaphragms in its expanded condition, [0029] Fig. 12 shows the annular barrier having projections restricting free expansion of the expandable sleeve, [0030] Fig. 13 shows another embodiment of an annular barrier, [0031] Fig. 14 shows yet another embodiment of an annular barrier, [0032] Fig. 15 shows an annular barrier in which the expandable sleeve has circumferential reinforcement rings, [0033] Fig. 16 shows an annular barrier in which the expandable sleeve has circumferential sealing elements and reinforcement rings, and [0034] Fig. 17 shows an annular barrier system. [0035] All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested. Detailed Description [0036] Annular barriers 1 are typically mounted into a well tubular structure, such as a production casing, before lowering the well tubular structure 300 into the borehole downhole. The well tubular structure 300 is constructed by well tubular structure parts assembled as a long well tubular structure string. The annular barriers 1 are mounted between the well tubular structure parts when mounting the well tubular structure string. [0037] The annular barrier 1 is used for a variety of purposes, all of which require that an expandable sleeve 3 of the annular barrier 1 is expanded so that the sleeve abuts the inside wall 101 of the borehole. The annular barrier 1 comprises a tubular part 2 surrounded by the expandable sleeve 3. The unexpanded sleeve has a cylindrical shape and at its ends it is connected with the tubular part. The expandable sleeve 3 is expanded by letting pressurised fluid 6 in through an expansion opening 9 of the tubular part into an annular barrier space 30 between the expandable sleeve 3 and the tubular part 2. [0038] The tubular part 2 is connected with the well tubular structure parts, e.g. by means of a thread connection, and forms part of the well tubular structure 300. Thus, the tubular part 2 and the well tubular structure parts together form the inside wall 301 of the well tubular structure 300, enclosing an inside space 302 of the well tubular structure. The expandable sleeve 3 may be expanded by pressurising the inside space 302 fully or partly opposite the expansion opening 9 of the tubular part 2. [0039] The annular barrier 1 furthermore has a first diaphragm 4 arranged in the annular barrier space 6, 7, which divides the annular barrier space into a barrier compartment 7 and an expansion compartment 6. The expansion compartment 6 is in fluid communication with an inside 302 of the tubular part 2 through an expansion opening 9, and the barrier compartment 7 is in fluid communication with the borehole 100 through a first barrier opening 10. The annular barrier 1 of Fig. 1 is shown as a cross-section along a longitudinal extension of the expandable sleeve 3 or an axial extension of the annular barrier and in its unexpanded and relaxed position, the line 22 being the centreline 22 of the annular barrier 1. The centreline indicates rotation symmetry around this line, i.e. the tubular part 2 in Fig. 1 is a hollow cylinder. In order to expand the expandable sleeve 3, pressurised fluid is injected into an expansion opening 9 expanding a cavity referred to as the expansion compartment 6 between the expandable sleeve 3 and the first diaphragm 4 of the annular barrier 1, so that the first diaphragm 4 and the expandable sleeve 3 are expanded. Thus, the first diaphragm 4 follows the shape of the expandable sleeve 3 during expansion of the sleeve as shown in Fig. 2. [0040] As shown in Figs. 1-4, each end of the expandable sleeve and the first diaphragm are fastened to the tubular part by means of a separate connection part without welding. Thus, the ends of both the expandable sleeve and the first diaphragm are fastened by the connection part pressing the sleeve end and the diaphragm end towards the tubular part. Each end of the expandable sleeve and the first diaphragm may thus be fastened to the tubular part by means of crimping, gluing, pressing, or heating and cooling. The heating and a subsequent cooling involve the step of first heating the material to increase the inner diameter of the connection part, and when the connection part is placed in its position opposite the sleeve and at least one diaphragm, the connection part is cooled down resulting is a decrease of its diameter again. The 7 connection part is tubular and arranged concentrically to the tubular part, and the connection part has a length le which is more than 10% and less than 50% of the sleeve length. [0041] The annular barrier 1 further comprises at least one sealing element 20 arranged in grooves 28 in a first part 26 of the connection part, and the sealing element 20 is thus facing the tubular part, as shown in Figs. 1-4. The connection part 12 has a second part 27 overlapping one end 31 of the expandable sleeve and one end 35 of the first diaphragm for pressing the end of the expandable sleeve and the first diaphragm towards the tubular part. [0042] The pressurised fluid used to expand the annular barrier may either be pressurised from the top of the borehole 100 and fed through the well tubular structure 300, or be pressurised in a locally sealed off zone in the well tubular structure. The pressurised fluid having an expansion pressure Pexpansion is injected (illustrated by an arrow) into the expansion compartment until the expandable sleeve 3 abuts the inside wall 101 of the borehole, which is shown in Fig. 2. The expandable sleeve 3 and the first diaphragm 4 are connected with the tubular part 2 using a connection part 12 at each end of the expandable sleeve 31, 32. When the annular barrier 1 has been expanded using a pressurised fluid and abuts the inside of the borehole wall 101, the annular barrier provides a seal between a first zone 102 and a second zone 103 of the borehole. Thus, the first zone 102 is on one side of the annular barrier 1 and the second zone 103 is on the other side of the annular barrier 1. [0043] When the pressure Pexpansion of the pressurised fluid is released in order to start production, the annular barrier 1 must be capable of withstanding a certain pressure P100 from the borehole 100 in order to prevent a collapse which would lead the barrier to become leaky. As an example, the annular barrier 1 is used to seal off a production zone 400 (shown in Fig. 17), and a pressure P400 in the production zone might build up inside the production zone 400 when a fluid, such as oil, starts to enter the production zone 400 from the surrounding formation 200. When the pressure P400 builds up in the production zone, the pressure against the annular barrier increases, and the seal made by the annular barrier may become leaky. This is due to the fact that the pressure inside the annular barrier is no longer the expansion pressure Pexpansion, and that the pressure inside the well tubular structure under normal operating conditions is typically much lower than the expansion pressure Pexpansion, and the pressure from the borehole P100 might then exceed the pressure P302 inside the well tubular structure. However, the annular barrier 1 of Figs. 2 and 3 comprises a barrier compartment 7 which is in fluid communication 8 with the borehole 100 through a first barrier opening 10, and since the barrier space 7 is in fluid communication with the first zone 102 of the borehole, the pressure P7 in the barrier compartment will build up as fluid flows from the first zone 102 and into the barrier compartment 7 (illustrated by an arrow), equalising the pressure in the barrier compartment 7 with the pressure in the first zone . [0044] The first diaphragm 4, shown in Figs. 3 and 4, ensures that the first zone pressure P102 and thus the borehole is sealed from the inside 302 of the well tubular structure 300. When the annular barrier is exposed to a pressure increase from the first zone 102 of the borehole 100, the pressure increases equivalently inside the barrier compartment 7, and therefore the expandable sleeve 3 will not be exposed to an increased difference in pressure between P102 and P7, causing the annular barrier to break its seal between the first zone 102 and second zone 103 of the borehole. [0045] In order for a diaphragm to withstand the pressure exerted on the diaphragm, it has to be made from a deformable material in order that it can be deformed and abut either the expandable sleeve or the tubular part in the annular barrier 1. Thus, the diaphragm is made of a material which is more flexible and/or deformable than the material of the expandable sleeve 3 and/or the tubular part 2. A diaphragm is typically much thinner than the expandable sleeve 3 and the tubular part 2 and therefore incapable of withstanding the pressures without being supported by an abutting element, such as the tubular part 2 or the expandable sleeve 3. [0046] In annular barriers using more than one diaphragm, as shown in Figs. 5-9, the diaphragms may abut each other, the outermost diaphragm being supported by an abutting element, such as the tubular part 2 or the expandable sleeve 3. The deformation of a diaphragm material may be elastic, plastic or a combination thereof. The deformation of both diaphragms and sleeves may also be referred to as expansion or expandable, since compared to the relaxed position, the material of the sleeve and diaphragms will be expanded during use. [0047] Fig. 3 shows a situation in which the first zone pressure P102 has exceeded the pressure P302 of the inside of the well tubular structure 300. Then fluid is entering the barrier compartment 7 from the first zone 102 through the first barrier opening 10, leading to pressure equalisation between the first zone pressure P102 and the barrier compartment pressure P7 and furthermore forcing the first diaphragm towards the tubular part 2. Fig. 4 shows the first 9 diaphragm 4 in an intermediate position, which illustrates a typical situation during pressure equalisation when fluid is flowing from the first zone 102 of the borehole and into the barrier compartment 7, before the first diaphragm 4 abuts the tubular part 2. [0048] The diaphragm and the sleeve may be connected with the tubular part 2 by means of a separate connection part 12. The connection part may be connected with the sleeve and the diaphragms by means of crimping, pressing, squeezing, heating and a subsequent cooling in order to first heat the material to increase the inner diameter of the connection part, and when the connection part is placed in its position opposite the sleeve and at least one diaphragm, the connection part is cooled down and its diameter is thus decreased again. [0049] As shown in Fig. 6, the expandable sleeve 3 is at its ends connected with a connection part 12. The connection part is connected with the tubular part and provided with sealing members 20 which may be arranged in grooves 28. [0050] When the expandable sleeve 3 of the annular barrier 1 is expanded, the diameter of the sleeve is expanded from its initial unexpanded diameter to a larger diameter. The expandable sleeve 3 has an outside diameter D and is capable of expanding to an at least 10% larger diameter, preferably an at least 15% larger diameter, more preferably an at least 30% larger diameter than that of an unexpanded sleeve. [0051] Furthermore, the expandable sleeve 3 has a wall thickness t, which is smaller than a length L, of the expandable sleeve, the thickness preferably being less than 25% of the length, more preferably less than 15% of the length, and even more preferably less than 10% of the length. [0052] The expandable sleeve 3 of the annular barrier 1 is made of metal. [0053] In Figs. 15 and 16, sections 14 of the sleeve 3 have increased thickness, which is obtained by ring-shaped parts being applied onto an outer face 33 of the expandable sleeve. This section 14 is also referred to, in some embodiments, as a reinforcement ring 14. [0054] In yet another embodiment, the thickness of the section 14 of the sleeve 3 is facilitated using a varying thickness sleeve 3. To obtain a sleeve of varying thickness 3, 14, techniques such as rolling, extrusion or die-casting may be used.

10 [0055] The annular barrier of Figs. 5-9 has a first diaphragm 4 and a second diaphragm 5, wherein the first 4 and second 5 diaphragms divide the annular barrier space 30 into the first barrier compartment 7, a second barrier compartment 8 and the expansion compartment 6. In situations in which the annular barrier may suddenly experience an unexpected high pressure in both the first zone 102 and the second zone 103 of the borehole, one more diaphragm may be arranged inside the annular barrier 1. In situations (please see Figs. 7 and 8) in which the annular barrier may suddenly experience an unexpected high pressure, a production zone 400 on one side of the annular barrier is a first zone 102 of the borehole with a first zone pressure P 102, and on the other side of the annular barrier is the second zone 103 of the borehole not forming part of the production zone. An example of such a situation in which the second zone pressure P103 suddenly increases substantially may be in the event of a gas leak further down the borehole 100, and the the annular barrier 1 may then suddenly experience an unexpected high pressure from the second zone pressure P103 even though the barrier was set up to seal a high production zone pressure. To avoid a potential breakdown of the seal due to an increased second zone pressure P103, the second diaphragm 5 is provided in the annular barrier 1. The expansion compartment is in fluid communication with an inside 302 of the well tubular structure 300 through an expansion opening 9, and the first barrier compartment 7 is in fluid communication with the first zone 102 of the borehole through a first barrier opening 10, and the second barrier compartment 8 is in fluid communication with the second zone 103 of the borehole through a second barrier opening 11. When the second zone pressure P103 builds up as shown in Fig. 7, fluid will flow (illustrated by an arrow) into the second barrier compartment 8, forcing the first diaphragm to abut the expandable sleeve 3 and the second diaphragm 5 to abut the tubular part 2, thereby obtaining the second zone pressure P103 inside the annular barrier 1. When the pressures on both sides of the expandable sleeve 3 are substantially equal, the annular barrier 1 will be capable of withstanding high pressures and still abut the inside of the borehole wall to make a tight seal, since the annular barrier 1 can maintain the same pressure inside the annular barrier as the highest pressure experienced by the annular barrier from the outside of the annular barrier 1. [0056] As can be seen in Fig. 1, the first barrier opening 10 is arranged closer to one of the connection parts 12 than the middle point Pm of the expandable sleeve 3. [0057] The annular barrier comprising both a first diaphragm 4 and a second diaphragm 5 is shown in four different situations in Figs. 5 to 9. Fig. 5 shows the unexpanded state of the 11 annular barrier 1. Fig. 6 shows an expanded state of the annular barrier 1, where a pressurised fluid (illustrated by an arrow) is injected through the expansion opening 9 in order to force the expandable sleeve to abut the inside 101 of the borehole 100. In this situation, the two diaphragms follow the shape of the expandable sleeve 3 during expansion of the sleeve. As already explained, Fig. 7 shows the situation in which the second zone pressure P103 is the highest pressure, thereby forcing the second diaphragm 5 to abut the expandable sleeve 3 and the first diaphragm 4 to abut the tubular part 2. Fig. 8 shows the situation in which the first zone pressure P102 is the highest, thereby forcing a fluid to enter the first barrier compartment 7 from the first zone 102 of the borehole 100 (illustrated by the arrow). When fluid enters the first barrier compartment 7, the first diaphragm 4 is forced towards the tubular part in that the first diaphragm 4 is forced to abut the second diaphragm 5 which is forced to abut the tubular part 2. Fig. 9 shows the first and second diaphragms 4, 5 in intermediate positions not abutting each other, nor abutting the expandable sleeve 3 or the tubular part 2. [0058] By having two diaphragms, the annular barrier can withstand a higher outside pressure from either the first zone 102 or the second zone 103. [0059] By using diaphragms instead of valves, the lifetime of an annular barrier may be increased significantly. Typical lifetimes of valves in downhole environments are around 5 years, and valve systems will then have to be replaced. Annular barriers are exposed to very few pressure changes, typically not many more than 20 pressure changes during the lifetime of an annular barrier. Therefore, annular barrier diaphragms can maintain their functionality for many years due to the absence of moving parts. The lifetime of the annular barrier using diaphragms will therefore only be limited by fatigue in the diaphragm materials, which, given the very few pressure changes, is a minor problem. Furthermore, it should be noted that a typical annular barrier has a length of 5 to 15 metres and preferably 10 metres to match standard well tubular parts and equipment for inserting well tubular parts into boreholes. The difference between the diameter of an expanded and an unexpanded annular barrier may typically be less than 10 centimetres, and even less than 5 centimetres, which over a length of 5 to 15 metres applies very little stress to the diaphragm. With this in mind, it is evident that an annular barrier using diaphragms is a very robust structure.

12 [0060] When the outside pressure drops again, the pressure inside the annular barrier 1 is equalised again by letting fluid out of the annular barrier into to the first zone 102 or the second zone 103. [0061] In Figs. 5-9, the diaphragms are shaped as hollow cylinders fastened at their ends to the connection parts and surrounding the tubular part which is surrounded by the expandable sleeve. [0062] Figs. 10A and 1OB show the annular barrier 1 having two diaphragms; each diaphragm is shaped as a hollow cylinder fastened at its one end to a connection part and at its other end to the tubular part 2. The tubular part 2 has an expansion opening 9 arranged in a middle part, and the ends of the diaphragms are connected with the tubular part 2 on opposite sides of the expansion opening 9 when seen in the cross-sectional view of Figs. 1OA and 1OB. At its ends nearest the expansion opening, the diaphragms are welded to the tubular part, and at its other ends the diaphragms are connected with the connection parts by means of a thread connection. The diaphragms may also be welded to the connection parts. [0063] In the annular barrier of Fig. 10A, both the first barrier opening 10 and the second barrier opening 11 are provided as penetrating the connection part, the expansion sleeve 3 and the diaphragm, providing fluid communication between the first zone 102 and the first barrier compartment and the second zone 103 and the second barrier compartment, respectively. [0064] In Fig. 1OB, the first barrier opening 10 and the second barrier opening 11 are provided as penetrating only the connection part. In this way, the expandable sleeve 3 and the diaphragms are not penetrated, resulting in a more simple design. [0065] The diaphragms in Figs. 1OA and lOB may also be manufactured from one cylinder fastened at its ends to the connection parts and at a middle part welded to the tubular part, and subsequently the expansion openings are provided therein and through the tubular part. [0066] By having two diaphragms connected on opposite sides of the expansion opening 9, the connection parts do not necessarily have a sealing member 20 to provide a seal towards the tubular part, since the diaphragms provide the seal so that fluid from the first or second zone 102, 103 does not enter the well tubular structure.

13 [0067] The annular barrier of Fig. 11 also has two diaphragms; a first diaphragm connected at its ends to the connection part and a second diaphragm which in its one end is connected with one connection part and in its other end is connected with the tubular part 2 near the expansion opening 9. The expansion opening 9 is provided in the tubular part 2 near the connection part in which only the first diaphragm is fastened. Thus, the expansion opening 9 is not arranged in the middle part of the tubular as in Figs. 10A and 10B. [0068] Even though Figs. 10A and 1OB show a first barrier opening 10 and a second barrier opening 11, the barrier openings may be replaced by a non-sealing connection between the connection part and the tubular part. In Fig. 11, the first barrier connection may be replaced in the same way by a leaky connection between the connection part and the tubular part. [0069] In the same way as in Fig. 10A and 1OB, the first diaphragm shown in Fig. 11 allows that a completely tight sealing connection is not needed between the connection part 12 and the tubular part 2 at the end of the annular barrier 1, where the first diaphragm 4 is connected to the connection part. [0070] Furthermore, the first diaphragm of Fig. 11 has the ability to expand substantially the entire volume of the annular barrier 1, as if it was connected with both connection parts, due to the fact that its connection with the tubular part 2 can be arranged so close to the connection part in which only the second diaphragm is connected that the first diaphragm can be expanded in substantially the entire volume of the annular barrier 1. [0071] As shown in Fig. 12, the annular barrier has a restriction element 13 in the form of a projecting part 13 as a prolongation of each of the connection parts and overlapping the expandable sleeve 3. The projecting part 13 of the connection part 12 increasingly tapers towards the expandable sleeve 3 until the projecting part 13 does not overlap the expandable sleeve 3 anymore and the expandable sleeve 3 is free to expand. [0072] In Fig. 12, a spacer 16 is separating the expandable sleeve 3 from the first diaphragm 4 to allow fluid to pass between them. Spacers 16 can be used to impose a gap between the expandable sleeve 3, the first and second diaphragms and the tubular part 2. The spacer may be flat or a step structure. The spacer may be a separate part or an integral part of the expandable sleeve, the diaphragms, the tubular part, or the connection part.

14 [0073] The projecting part 13 has the purpose of restricting the expansion of the expandable sleeve 3 so that the curvature of the expandable sleeve 3 when expanded is more S-shaped when seen in the cross-sectional view along the longitudinal extension of the sleeve. It is hereby obtained that the expandable sleeve 3 does not fracture during expansion and that the cross sectional profile of the expandable sleeve 3 is capable of withstanding a higher collapse pressure than a known annular barrier. Thus, the expandable sleeve 3 is more restricted in expanding at the first point than at the second point. Furthermore, due to the fact that the projecting part 13 may be made from a less flexible metal alloy and tapers from the connection towards the second point, the expandable sleeve 3 is less restricted in expanding along with the decreasing thickness of the projecting part. [0074] The first barrier opening 10 may also be arranged directly in the expandable sleeve 3 as shown in Figs. 1-4 and 13, resulting in a very simple design which is easy to manufacture and implement in existing manufacturing procedures. [0075] In Fig. 14, the annular barrier further comprises a sealing element 15B arranged on an outer face 36 of the expandable sleeve for sealing against an inside 101 of the borehole 100. The sealing element thus has a sealing surface 37 facing the inner side of the borehole. The sealing surface may be serrated or have another kind of deformable surface. The sealing elements may be made of polymers, elastomers, natural or synthetic rubber or silicone. The sealing element 15 is arranged on the outer face 36 of the expandable sleeve for sealing against the inside of the borehole, the sealing element having an uneven thickness along the axial extension, the sealing element covering at least 50% of the sleeve length. [0076] In order to increase the collapse pressure, an anti-collapsing element 14 is arranged on the outside of the sleeve which is a section 14 of the expandable sleeve and may have an increased thickness when seen in a cross-sectional view along the longitudinal extension of the sleeve as shown in Fig. 15. When expanding the sleeve, this section of the sleeve is expanded less than other sections of the sleeve along a non-inclining part of the expandable sleeve in its expanded state, resulting in a corrugated shape of the sleeve as seen in Fig. 16. [0077] Also, Fig. 15 shows the possibility of using a valve 19 instead of the barrier opening 10. The expansion opening 9, the first barrier opening 10 and/or the second barrier opening 11 may in some embodiments be replaced by a valve to control the flow from the borehole into the 15 barrier compartments or to control the flow from the inside of the well tubular structure 300 and into the expansion compartment 6. Also the flow direction may be restricted using one-way valves. [0078] In another embodiment, the thickness of the section of the sleeve is increased by fastening a ring-shaped part onto the sleeve. The ring-shaped part is the section 14 and is fastened onto the inner surface. [0079] As shown in Fig. 16, on the outer face of the expandable sleeve 3, sealing elements 15 are arranged opposite the sections of the sleeve having an increased thickness. When the sleeve is expanded, the sealing elements 15 fill up the gap occurring during expansion. In order to fit the gap better, the sealing elements 15 have a tapering or triangular cross-sectional shape. [0080] When the annular barrier is installed, it forms part of a well tubular structure as shown in Fig. 17, providing an annular barrier system 500. In Fig. 17, the system comprises two annular barriers sealing a production zone 400. The barriers are arranged in a horizontal part of the well and seen in its expanded condition. [0081] An expansion tool may be used to expand the annular barrier and may comprise an isolation device for isolating a first section outside the passage or valve between an outside wall of the tool and the inside wall of the well tubular structure. The pressurised fluid is obtained by increasing the pressure of the fluid in the isolation device. When a section of the well tubular structure outside the passage of the tubular part is isolated, it is not necessary to pressurise the fluid in the entire well tubular structure, just as no additional plug is needed as is the case in prior art solutions. When the fluid has been injected into the space, the passage or valve is closed. [0082] The tool may also use coiled tubing for expanding the expandable sleeve 3 of an annular barrier 1 or of two annular barriers at the same time. A tool with coiled tubing can pressurise the fluid in the well tubular structure without having to isolate a section of the well tubular structure. However, the tool may need to plug the well tubular structure further down the borehole from the two annular barriers or barriers 1 to be operated. The annular barrier system of the present invention may also employ a drill pipe or a wireline tool to expand the sleeve.

16 [0083] In the event that the tool cannot move forward in the well tubular structure 3, the tool may comprise a downhole tractor, such as a Well Tractor®. [0084] Also, the diaphragm may be made from an expandable metal material. [0085] Also, the diaphragm may be cylindrical or corrugated. [0086] The expandable sleeve may be capable of expanding to an at least 10% larger diameter, preferably an at least 15% larger diameter, more preferably an at least 30% larger diameter, than that of an unexpanded sleeve, and it may have a wall thickness which is smaller than a length of the expandable sleeve, the thickness preferably being less than 25% of its length, more preferably less than 15% of its length, and even more preferably less than 10% of its length. [0087] In one embodiment, the sleeve may comprise a plurality of sections 14 arranged along the non-inclining part of the sleeve and having a mutual distance between them. The expandable sleeve may have an outer face onto which at least one sealing element is arranged opposite a section of the sleeve having an increased thickness. The sealing elements may have a tapering or triangular cross-sectional shape. [0088] In another embodiment, an annular barrier as described above may be comprised in an annular barrier system comprising a well tubular structure, and the annular barrier is arranged as part of the well tubular structure. The system may further comprise an inflow control section. Further, the system may comprise a second annular barrier, wherein the inflow control section is arranged between the two annular barriers. [0089] Also disclosed is a method of placing an annular barrier as described above in an annulus comprising the steps of connecting the annular barrier with a well tubular structure, placing the unexpanded annular barrier in a desired position downhole, and expanding the sleeve by pressurised fluid from within the tubular part. The method of placing an annular barrier may further comprise the step of pressurising the well tubular structure in order to provide the pressurised fluid for expanding the sleeve. [0090] The method of placing an annular barrier may comprise the step of placing a pressure tool in the vicinity of the annular barrier for expanding the sleeve by providing a pressurised 17 fluid locally in the well tubular structure. Moreover, said method may comprise the step of opening the inflow control section. [0091] Further disclosed is a method of using annular barriers as described above in an annulus to seal off an inflow control section, comprising the steps of connecting two annular barriers with a well tubular structure and in between them an inflow control section, placing the two annular barriers and the inflow control section in a desired position downhole, pressurising the tubular part and expanding the annular barriers by pressurised expansion fluid from within the tubular part for providing a zone isolation between a first zone and a second zone of the borehole, the first zone having a first fluid pressure and the second zone having a second fluid pressure, stopping the pressurising of the tubular part, activating the inflow control section for starting a production of fluid into the well tubular structure, and equalising the pressure between the first and/or second fluid pressure and the pressure within the space by letting fluid into the space. [0092] In one embodiment, the tool comprises a reservoir containing the pressurised fluid, e.g. when the fluid used for expanding the sleeve 3 is cement, gas or a two-component compound. [0093] An annular barrier 1 may also be called a packer or similar expandable means. The well tubular structure can be the production tubing or casing or a similar kind of tubing downhole in a well or a borehole. The annular barrier 1 can be used both between the inner production tubing and an outer tubing in the borehole or between a tubing and the inner wall of the borehole. A well may have several kinds of tubing, and the annular barrier 1 of the present invention can be mounted for use in all of them. [0094] The valve may be any kind of valve capable of controlling flow, such as a ball valve, butterfly valve, choke valve, check valve or non-return valve, diaphragm valve, expansion valve, gate valve, globe valve, knife valve, needle valve, piston valve, pinch valve or plug valve. [0095] The expandable tubular metal sleeve 3 may be a cold-drawn or hot-drawn tubular structure. The sleeve may be seamless or welded. [0096] The expandable tubular metal sleeve 3 may be extruded, die-cast or rolled, e.g. hot rolled, cold rolled, roll bended etc., and subsequently welded.

18 [0097] The fluid used for expanding the expandable sleeve 3 may be any kind of well fluid present in the borehole surrounding the tool and/or the well tubular structure. Also, the fluid may be cement, gas, water, polymers, or a two-component compound, such as powder or particles mixing or reacting with a binding or hardening agent. Part of the fluid, such as the hardening agent, may be present in the space before injecting a subsequent fluid into the space. [0098] Although the invention has been described in the above in connection with preferred embodiments of the invention, it will be evident for a person skilled in the art that several modifications are conceivable without departing from the invention as defined by the following claims.

Claims (5)

1. An annular barrier arranged in a borehole for providing zone isolation between a first zone and a second zone of the borehole, the annular barrier having an axial extension and comprising: - a tubular part for mounting as part of a well tubular structure or casing and having an expansion opening, - an expandable sleeve surrounding the tubular part, each end of the expandable sleeve being connected with the tubular part, the expandable sleeve having a sleeve length and extending along the axial extension, the expandable sleeve having a middle point which is positioned at half the sleeve length from the ends, - an annular barrier space between the tubular part and the expandable sleeve, wherein a first diaphragm arranged in the annular barrier space divides the annular barrier space into a barrier compartment and an expansion compartment, and wherein the expansion compartment is in fluid communication with an inside of the tubular part through the expansion opening, and the barrier compartment is in fluid communication with the borehole through a first barrier opening, and wherein each end of the expandable sleeve and the first diaphragm are fastened to the tubular part by means of a separate connection part without welding, the connection part being tubular and arranged concentrically to the tubular part, and the connection part having a length which is less than 50% of the sleeve length, the first barrier opening being arranged closer to one of the connection parts than the middle point of the expandable sleeve.

2. An annular barrier according to claim 1, wherein each end of the expandable sleeve and the first diaphragm are fastened to the tubular part by means of crimping, gluing, pressing, heating or cooling.

3. Annular barrier according to claim 1 or 2, further comprising at least one sealing element arranged in grooves in a first part of the connection part and facing the tubular part.

4. Annular barrier according to any one of claims I to 3, wherein the connection part has a second part overlapping one end of the expandable sleeve and the first diaphragm for pressing the end of the expandable sleeve and the first diaphragm towards the tubular part. 20

5. Annular barrier according to any one of claims 1 to 4, further comprising a sealing element arranged on an outer face of the expandable sleeve for sealing against the inside of the borehole, the sealing element having an uneven thickness along the axial extension, the sealing element covering at least 50% of the sleeve length. Welltec A/S Patent Attorneys for the Applicant/Nominated Person SPRUSON & FERGUSON