A downhole packer assembly

Abstract

A downhole packer assembly (1) for expansion of a metal patch in a well (5) downhole in a well tubular metal structure (7), comprising a body part (9) having a longitudinal extension (A) and a central part (11), a first expandable tubular element (13) surrounding the body part and being connected with the body part on one side of the central part and having a first outer face (15), a second expandable tubular element (17) surrounding the body part, being connected with the body part on an opposite side of the central part, and having a second outer face (19), a metal patch (21), having a first end (23), a second end (25), an inner face (27) and an outer face (29) configured to face and abut the well tubular metal structure, and having a first predefined length (L), wherein the metal patch surrounds the first expandable tubular element and the second expandable tubular element, wherein the first expandable tubular element is arranged at a first distance (D1) from the second expandable tubular element in the longitudinal extension in a first operational state, and wherein the first expandable tubular element is arranged at a second distance (D2) from the second expandable tubular element in the longitudinal extension in a second operational state, where the second distance is larger than the first distance.

Description

[0001] A DOWNHOLE PACKER ASSEMBLY

[0002] Technical field

[0003] A downhole packer assembly for expansion of a metal patch in a well downhole in a well tubular metal structure.

[0004] Description

[0005] When a well tubular metal structure becomes perforated or has sprung leaks, there is a need to close the leak or perforations in order to close all fluid communication between an annulus and the interior of the well tubular. Such patching has often been done using metal patches, where a downhole packer assembly may be introduced into the well tubular structure, and an expandable tubular element may be inflated in order to expand the metal patch towards the inner face of the well tubular metal structure to close the leak or the perforation.

[0006] There is often a need to apply a metal patch in a downhole position, where the metal patch has a relatively long length, which means that the patch has to be expanded using a mandrel or an expandable tubular element, or using a downhole tool having more than one expandable tubular element, expanding the metal patch in two or more locations at the same time. However, a problem with the use of multiple expandable tubular elements is that the expandable tubular element is arranged within the longitudinal boundary of the metal patch, which means that the expandable tubular element is not capable of expanding the ends of the patch sufficiently, meaning that a central part of the patch is fully expanded, while the ends of the patch may be expanded to a lesser degree, thereby causing a small restriction in the patch.

[0007] It is an object of the present invention to wholly or partly overcome the disadvantages and drawbacks of the prior art. In accordance with the invention, there is provided a downhole packer assembly for expansion of a metal patch in a well downhole in a well tubular metal structure, comprising :

[0008] - a body part having a longitudinal extension and a central part,

[0009] - a first expandable tubular element surrounding the body part and being connected with the body part on one side of the central part and having a first outer face,

[0010] P2864PC00 - a second expandable tubular element surrounding the body part, being connected with the body part on an opposite side of the central part and having a second outer face, and

[0011] - a metal patch having a first end, a second end, an inner face and an outer face configured to face and abut the well tubular metal structure, and having a first predefined length, wherein the metal patch surrounds the first expandable tubular element and the second expandable tubular element, wherein the first expandable tubular element is arranged at a first distance from the second expandable tubular element in the longitudinal extension in a first operational state, and wherein the first expandable tubular element is arranged at a second distance from the second expandable tubular element in the longitudinal extension in a second operational state, where the second distance is larger than the first distance.

[0012] In one or more exemplary embodiments, the body part comprises a first tubular part having a first end and a second end, and a second tubular part having a first end and a second end, where the second end of the first body part is arranged at a first distance from the first end of the second body part in the first operational state, and where the second end of the first body part is arranged at a second distance from the first end of the second body part in the second operational state. The first expandable tubular element may surround the first body part and be fixed relative to the first body part, and the second expandable tubular element may surround the second body part and may be fixed relative to the second body part.

[0013] In one or more exemplary embodiments, the position of the first expandable tubular element is secured at the first distance relative to the second expandable tubular element in the first operational state, and when an expansion fluid reaches a predefined pressure threshold, the expansion fluid provides a force to the first expandable tubular element and / or the second expandable tubular element to release the first expandable tubular element and / or the second expandable tubular element relative to the second tubular element. Alternatively, the first and second tubular parts may be released, allowing a distance increase from the first distance to the second distance.

[0014] In one or more exemplary embodiments, in a first operational state, the outer face of the first expandable tubular element and the outer face of the second expandable tubular element are in contact with the inner face of the metal patch, defining a centre volume.

[0015] P2864PC00 In one or more exemplary embodiments, the body part has a first fluid outlet in fluid communication with an expandable space of the first expandable tubular element and a second fluid outlet in fluid communication with an expandable space of the second expandable tubular element.

[0016] In one or more exemplary embodiments, the body part has a third fluid outlet in fluid communication with a confined space defined by the first expandable tubular element, the second expandable tubular element and an inner face of the metal patch.

[0017] In one or more exemplary embodiments, the third fluid outlet is positioned in the central part.

[0018] In one or more exemplary embodiments, the third fluid outlet comprises a first pressurereduction valve having a first fluid pressure input and a first fluid pressure output, where the first fluid pressure output is lower than the first fluid pressure input.

[0019] In one or more exemplary embodiments, the third fluid outlet comprises a second pressure-reduction valve having a second fluid pressure input and a second fluid pressure output, where the second fluid pressure output is lower than the first fluid pressure output.

[0020] In one or more exemplary embodiments, the first fluid pressure output is at least 20 bars lower than the first fluid pressure input, preferably the first fluid pressure output is 25 bars lower than the first fluid pressure input, more preferably the first fluid pressure output is 30 bars lower than the first fluid pressure input.

[0021] In one or more exemplary embodiments, the third fluid outlet comprises a third pressure-reduction valve having a third fluid pressure input and a third fluid pressure output, where the third fluid pressure output is lower than the third fluid pressure input.

[0022] In one or more exemplary embodiments, the second fluid pressure output and / or the second fluid pressure outlet is at least 150 bars lower than the first fluid pressure input, preferably the first fluid pressure output is 180 bars lower than the first fluid pressure input, more preferably the first fluid pressure output is 220 bars lower than the first fluid pressure input.

[0023] P2864PC00 In one or more exemplary embodiments, the third pressure-reduction valve may be configured to be activated when the downhole packer assembly transitions from its first operational state to an intermediate operational state and / or to its second operational state.

[0024] In one or more exemplary embodiments, the third pressure-reduction valve may be part of the first pressure-reduction valve and / or the second pressure-reduction valve and may be configured to provide a third pressure-reduction value that is different from the first pressure reduction-value of the first pressure-reduction valve and / or different from the second pressure-reduction value of the second pressure-reduction valve.

[0025] In one or more exemplary embodiments, the first expandable tubular element is secured relative to the second expandable tubular element by an extension tubular having a first end connected to the first expandable tubular element and a second end, where the extension tubular is configured to elongate from a first length to a second length at a predefined force threshold in the confined space.

[0026] In one or more exemplary embodiments, the first expandable tubular element is secured relative to the second expandable tubular element by a breakable tubular having a first end connected to the first expandable tubular element and a second end, where the extension tubular is configured to break at a predefined force threshold in the confined space and release the first expandable tubular element relative to the second expandable tubular element.

[0027] In one or more exemplary embodiments, the predefined force threshold is 150 bars of pressure in the confined space, wherein the predefined force threshold is 180 bars of pressure in the confined space, or more preferably the predefined threshold is 200 bars of pressure in the confined space.

[0028] Furthermore, the downhole packer assembly may comprise a motor driving a pump for generating expansion fluid with a fluid pressure.

[0029] In one or more exemplary embodiments, the downhole packer assembly may be part of a wireline tool. This means that e.g. the body part and the first and / or second expandable tubular(s) may be parts of a wireline tool, where a wireline connects the tool to the surface of a borehole when deployed and provides electrical communication between the tool and a surface rig in order to drive the motor.

[0030] P2864PC00 In one or more exemplary embodiments, the downhole packer assembly may be part of a coiled tubing tool. This means that e.g. the body part and the first and / or second expandable tubular(s) may be parts of a coiled tubing tool, where a coiled tubing connects the tool to the surface of a borehole when deployed and provides electrical and / or fluid communication between the tool and a surface rig in order to conduct the expansion fluid at a determined fluid pressure and / or electricity for driving the motor.

[0031] In one or more exemplary embodiments, the downhole packer assembly may be part of a drill pipe tool. This means that e.g. the body part and the first and / or second expandable tubular(s) may be parts of a drill pipe tool, where a drill pipe connects the tool to the surface of a borehole when deployed and provides fluid communication between the tool and a surface rig in order to conduct the expansion fluid at a determined fluid pressure.

[0032] The downhole packer assembly may comprise a pressure booster when driven by pressurised fluid from the coiled tubing or drill pipe, and the pressure booster may be a fluid displacement pump, such as a gear pump.

[0033] In one or more exemplary embodiments, the downhole packer may be conveyed into a downhole position using coiled tubing. Alternatively, the downhole packer may be conveyed into a downhole position using a drill pipe. This means that the downhole packer does not necessarily have to be introduced into the downhole position using a wireline tool having a pump, as the expansion fluid for the downhole packer may be provided from the surface via the coiled tubing and / or the drill pipe.

[0034] In one or more embodiments, the downhole packer may be part of a tool-string having a centraliser. The centraliser may be used to ensure that the downhole packer is in a central position inside the borehole and / or inside a well tubular metal structure ensuring that the expandable tubular element of the downhole packer expands from a central position inside the borehole and / or the well tubular metal structure.

[0035] In addition, the downhole packer assembly may comprise a central part being connected with the first expandable tubular element and the second expandable tubular element, so as to allow the first expandable tubular element and the second expandable tubular element to move in relation to each other and / or to move the central part from the first operational state towards the second operational state. The movement may occur when

[0036] P2864PC00 a predetermined expansion pressure is reached inside the first expandable tubular element, inside the second expandable tubular element and / or in a confined space between the first expandable tubular element and the second expandable tubular element.

[0037] Furthermore, the central part may comprise a securing part.

[0038] Thus, the securing part may be in the form of a groove creating a weakness in the central part.

[0039] Also, the central part may comprise a first securing part connected to the first expandable tubular element and a second securing part connected to the second expandable tubular element.

[0040] Furthermore, the securing part may be in the form of a tubular that has a deformation profile allowing the tubular to elongate at the predefined force threshold.

[0041] In addition, the securing part configured to release the first expandable tubular element relative to the second expandable tubular element may be a telescopic element made of coincident element parts held together by shear pins until a certain differential pressure is reached, and the element parts are allowed to move, providing a telescopic elongation of the securing part.

[0042] The invention and its many advantages will be described in more detail below with reference to the accompanying schematic drawings, which for the purpose of illustration show some non-limiting embodiments and in which:

[0043] Fig. 1 shows a partly cross-sectional view of a downhole packer assembly in accordance with the present disclosure in a first operational state,

[0044] Fig. 2 shows a partly cross-sectional view of a downhole packer assembly in accordance with the present disclosure in an intermediate operational state,

[0045] Fig. 3A and 3B show a partly cross-sectional view of a downhole packer assembly in accordance with the present disclosure in a second operational state,

[0046] P2864PC00 Fig. 4 shows a perspective view of an embodiment of a downhole tool for a downhole packer assembly in accordance with the present disclosure,

[0047] Fig. 5 shows a cross-sectional view of the tool shown in Fig. 4, and

[0048] Figs. 6A and 6B show a side view of the tool shown in Fig 4 in a first operational state and a second operational state, respectively.

[0049] Various exemplary embodiments and details are described below, with reference to the figures when relevant. It should be noted that the figures may or may not be drawn to scale and that elements of similar structures or functions are represented by like reference numerals throughout the figures. It should also be noted that the figures are only intended to facilitate the description of the embodiments. They are not intended as an exhaustive description of the disclosure or as a limitation on the scope of the disclosure. In addition, an illustrated embodiment need not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practised in any other embodiments even if not so illustrated, or if not so explicitly described.

[0050] Fig. 1 shows a partly cross-sectional view of a downhole packer assembly 1 for expansion of a metal patch 21 in a well 5 downhole in a well tubular metal structure 7, comprising a body part 9 having a longitudinal extension A and a central part 11, a first expandable tubular element 13 surrounding the body part 9 and being connected with the body part 9 on one side of the central part 11 and having a first outer face 15. The downhole packer assembly 1 further comprises a second expandable tubular element 17 surrounding the body part 9, being connected with the body part 9 on an opposite side of the central part 11 and having a second outer face 19.

[0051] The downhole packer assembly 1 further comprises a metal patch 21 having a first end 23, a second end 25, an inner face 27 and an outer face 29 configured to face and abut the well tubular metal structure 7, and having a first predefined length L, wherein the metal patch 21 surrounds the first expandable tubular element 13 and the second expandable tubular element 17.

[0052] Fig. 1 shows the downhole packer assembly 1 in a first operational state, where the first expandable tubular element 13 is arranged at a first distance DI from the second expandable tubular element 17 in the longitudinal extension A. The first operational

[0053] P2864PC00 state of the downhole packer assembly 1 may be seen as an operational state where the downhole packer assembly 1 is in an operational state and may be conveyed into the borehole, where the first expandable tubular element 13, the second expandable tubular element 17 and the metal patch 21 have a first radial extension. The first radial extension is smaller than the inner diameter of the well tubular metal structure 7, allowing the downhole packer assembly 1 to be conveyed safely into a position inside the well tubular metal structure 7, where the downhole packer assembly 1 is to be deployed by expanding the metal patch 21 to e.g. patch a leak and / or a perforation in the well tubular metal structure 7.

[0054] The body part 9 may comprise a first fluid outlet 31 and a second fluid outlet 33 configured to provide fluid communication into an expandable space in the first expandable tubular element 13 and the second expandable tubular element 17, respectively. The first fluid outlet 31 may be positioned on a first tubular part 35, where the first expandable tubular element 13 is attached to the first tubular part 35, and where the second fluid outlet 33 may be positioned on a second tubular part 37, where the second expandable tubular element 17 may be attached to the second tubular part 37. The first tubular part 35 and the second tubular part 37 may be separated by the central part 11, where the central part 11 may comprise a third fluid outlet 39.

[0055] In the first operational state, the metal patch 21 may be held in its position via frictional forces between the first expandable tubular element 13 and the second expandable tubular element 17, where the diameter of the metal patch 21 in its unexpanded state (first operational state) may be smaller than an outer diameter of the first expandable tubular element 13 and the second expandable tubular element 17, thereby ensuring that the metal patch 21 is secured in its position relative to the body part 9 during conveyance towards the bottom of the well 5 or in a direction towards the surface.

[0056] A downhole system comprising the downhole packer assembly 1 may also comprise a positive displacement pump 43 for pumping liquid out of the first fluid outlet 31, the second fluid outlet 33 and the third fluid outlet 39 to expand the first expandable tubular element 13 and the second expandable tubular element 17, and out of the third fluid outlet 39 into a confined space 41 which is defined by the volume between the body part 9, the first expandable tubular element 13, the second expandable tubular element 17 element and the inner face 27 of the metal patch 21. The positive displacement pump 43 may comprise a housing having a first end closest to a top of the well 5 and a second end facing opposite the first end, i.e. facing down the well 5. The positive

[0057] P2864PC00 displacement pump 43 is connected to the top via a wireline 45 and a cable head 47. The positive displacement pump 43 may comprise an electrical control. The positive displacement pump 43 may further comprise a motor driving the pump 43.

[0058] Fig. 2 shows the downhole packer assembly 1 in an intermediate operational state, where the first expandable tubular element 13 and the second expandable tubular element 17 have been expanded by introducing fluid into a first expandable space 49 from the first fluid outlet 31 and by introducing fluid under pressure into a second expandable space 51 from the second fluid outlet 33. The first expandable tubular element 13 and the second expandable tubular element 17 expand the metal patch 21 to come into contact with an inner surface 53 of the well tubular metal structure 7. Furthermore, in order to expand a central part 55 of the metal patch 21, a fluid under pressure is introduced via the third fluid outlet 39 into the confined space 41, where the fluid pressure expands the central part 55 of the metal patch 21 to come into contact with the inner surface 53 of the well tubular metal structure 7. In the intermediate operational state shown in Fig. 2, the distance between the first expandable tubular element 13 and the second expandable tubular element 17 is maintained at the same distance DI as seen in the first operational state in Fig. 1.

[0059] The distance between the first expandable tubular element 13 and the second expandable tubular element 17 may be maintained using a securing part 57 configured to release the first expandable tubular element 13 relative to the second expandable tubular element 17, or vice versa, at a predefined force threshold. The securing part 57 may be in the form of a tubular that has a deformation profile allowing the tubular to elongate at the predefined force threshold. In this embodiment, the securing part 57 may be in the form of a first breakable part 59 which connects the first tubular part 35 to the central part 11 and a second breakable part 61 which connects the second tubular part 37 to the central part 11 and is configured to break at the predefined force threshold.

[0060] The expansion fluid which is introduced via the first fluid outlet 31, the second fluid outlet 33 and the third fluid outlet 39 may be introduced into the first and second expandable space as well as the confined space 41 at a pressure. However, the expansion fluid entering the confined space 41 via the third fluid outlet 39 may have a lower pressure than the expansion fluid entering the first fluid outlet 31 and the second fluid outlet 33. By having a lower pressure, the first expandable tubular element 13 and the second expandable tubular element 17 may first expand the metal patch 21 in the

[0061] P2864PC00 areas where the expandable tubular elements 13, 17 are in contact with the inner face 27 of the metal patch 21, while the central part 55 of the metal patch 21 may be expanded subsequently as the pressure inside the expandable tubular elements 13, 17 is higher than the pressure inside the confined space 41.

[0062] When the central part 55 of the metal patch 21 and the part of the metal patch 21 that is in contact with the expandable tubular elements 13, 17 have been expanded to their position as shown in Fig. 2, it may be seen that the first end 23 of the metal patch 21 and the second end 25 of the metal patch 21 have a smaller diameter than the central part 55 of the metal patch 21. This smaller diameter of the ends 23, 25 causes a restriction in the well tubular metal structure 7 and may limit the flow of fluid past the metal patch 21. Thus, in order to expand the first end 23 and / or the second end 25 of the metal patch 21, the fluid pressure inside the confined space 41 may be increased up to a predefined threshold. When the fluid pressure inside the confined space 41 has reached or surpassed the predefined threshold, the fluid pressure inside the confined space 41 applies a force in the longitudinal direction to the first expandable tubular element 13 and the second expandable tubular element 17 in the directions of arrows B, where the force at the predefined threshold exceeds the force threshold of the securing part 57, the securing part 57 being configured to release the first expandable tubular element 13 relative to the second expandable tubular element 17, or vice versa, allowing the downhole packer assembly 1 to enter its second operational state.

[0063] Fig. 3A shows the downhole packer assembly 1 in its second operational state where the force of the fluid pressure inside the confined space 41 has exceeded a threshold, allowing the force threshold of the securing part 57 to exceed the threshold as well, where the first expandable tubular element 13 has moved in the direction of arrow Cl, and the second expandable tubular element 17 has moved in the direction of arrow C2, causing the distance between the first expandable tubular element 13 and the second expandable tubular element 17 to increase to distance D2. This increase in distance to D2 allows the first expandable tubular element 13 to expand the first end 23 of the metal patch 21 and the second expandable tubular element 17 to expand the second end 25 of the metal patch 21. As the first expandable tubular element 13 and the second expandable tubular element 17 are expanded, and the expandable spaces 49, 51 are under high pressure, the movement of the expandable tubular elements 13, 17 allows the ends 23, 25 of the metal patch 21 to be expanded as the expandable tubular elements 13, 17 operate as a mandrel, where the expandable tubular elements 13, 17

[0064] P2864PC00 have a diameter that is larger than the inner diameter of the ends 23, 25 causing the ends to plastically deform into the position shown in Fig. 3B.

[0065] The movement of the first expandable tubular element 13 may be caused by the release of the first tubular part 35 from the central part 11 by breaking the first breakable part 59, and / or the movement of the second expandable tubular element 17 may be caused by the release of the second tubular part 37 from the central part 11 by breaking the second breakable part 61. The first tubular part 35 and the second tubular part 37 may be connected with the central part 11 via an inner tubular part 63 which allows the first tubular part 35 and the second tubular part 37 to slide relative to the central part 11 after the release of the securing part 57.

[0066] An alternative version of the securing part 57 may be seen in Fig. 3B, where the securing part 57 may be in the form of a first securing tubular 65 connecting the first tubular part 35 with the central part 11 and a second securing tubular 67 connecting the second tubular part 37 with the central part 11. The securing tubulars 65, 67 may be in the form of tubulars that are arranged to elongate at a predefined force threshold so that the force of the fluid pressure inside the confined space 41 causes the first tubular part 35 to move in the direction shown by arrow Cl, and the second tubular part 37 to move in the direction shown by arrow C2, thereby allowing the distance between the first expandable tubular element 13 and the second expandable tubular element 17 to move to its second operational state as seen in Fig. 3B by stretching and elongating the first securing tubular 65 and the second securing tubular 67.

[0067] Fig. 4 is a perspective view of one embodiment of a downhole packer assembly 101 for expansion of a metal patch (not shown) in a first operational state. The downhole packer assembly 101 comprises a body part 109 having a longitudinal extension A and a central part 111, a first expandable tubular element 113 surrounding the body part 109 and being connected with the body part 109 on one side of the central part 111 and having a first outer face 115. The downhole packer assembly 101 further comprises a second expandable tubular element 117 surrounding the body part 109, being connected with the body part 109 on an opposite side of the central part 111 and having a second outer face 119.

[0068] Fig. 4 shows the downhole packer assembly 101 in a first operational state, where the first expandable tubular element 113 is arranged at a first distance from the second expandable tubular element 117 in the longitudinal extension A, as seen in Fig. 1. The

[0069] P2864PC00 first operational state of the downhole packer assembly 101 may be seen as an operational state where the downhole packer assembly 101 is in an operational state and may be conveyed into the borehole, where the first expandable tubular element 113 and the second expandable tubular element 117 have a first radial extension.

[0070] The downhole packer assembly 101 shown in Fig. 4 has a function similar to that of the downhole packer assembly 1 of Figs. 1-3. The body part 109 may comprise a first fluid outlet 131 and a second fluid outlet 133, as shown in Fig. 5, configured to provide fluid communication into an expandable space in the first expandable tubular element 113 and the second expandable tubular element 117, respectively. The first fluid outlet 131 may be positioned on a first tubular part 135, where the first expandable tubular element 113 is attached to the first tubular part 135, where the second fluid outlet 133 may be positioned on a second tubular part 137, and where the second expandable tubular element 117 may be attached to the second tubular part 137. The first tubular part 135 and the second tubular part 137 may be separated by the central part 111, where the central part 111 may comprise a third fluid outlet 139 and a fourth fluid outlet 140 for providing fluid pressure to expand a central part of a metal patch which extends similarly to the metal patch 21 shown in Fig. 1, which surrounds the first expandable tubular element 113 and the second expandable tubular element 117 as well as the central part 111.

[0071] The downhole packer assembly 101 may further comprise a mandrel 169 which extends coaxially with the first body part 109, where the mandrel 169 extends along the longitudinal extension A from a first end 171 of the downhole packer assembly 101 to an opposite end 173 of the downhole packer assembly 101. As shown in Fig. 6A, the mandrel 169 comprises a fluid communication channel 174 which provides fluid communication to the first fluid outlet 131, the second fluid outlet 133, the third fluid outlet 139 and the fourth fluid outlet 140, where the fluid communication channel 174 is configured to provide a pressurised fluid in order to expand the metal patch (not shown) by expanding the first expandable tubular element 113 and the second expandable tubular element 117, as well as provide fluid pressure in the volume between the first expandable tubular element 113 and the second expandable tubular element 117 via the third fluid outlet 139 and the fourth fluid outlet 140 into the confined space 41, as shown in Figs. 1-3.

[0072] The central part 111 comprises a first securing part 157 which is arranged in an area between the third fluid outlet 139 and the fourth fluid outlet 140 and is configured to

[0073] P2864PC00 be positioned in a central area of the patch (not shown), where the first securing part 157 may be in the form of a groove 175, creating a weakness in the central part 111. The central part 111 may comprise a first central part 177 and a second central part 179, where the groove 175 creates a boundary between the first central part 177 and the second central part 179. The first central part 177, the second central part 179 and the groove 175 may be formed of a tubular element 181, where the tubular element 181 of the first central part 177 and the second central part 179 may have a first material thickness, while the groove 175 may have a second material thickness which is smaller than the first material thickness, as seen in Fig. 5.

[0074] The first central part 111 is connected with the first expandable tubular element 113, and the second central part 179 is connected with the second expandable tubular element 117. The groove 175 may function as a breakable part 159 which is configured to break when a predefined force is applied onto the first central part 177 and the second central part 179 in opposite directions (shown by arrows Cl, C2 in Fig. 3A and 3B) by way of internal fluid pressure (B as shown in Fig. 2) inside the confined space (41 in Fig. 3A and 3B). When the predefined force is applied onto the first central part 177 and the second central part 179 in opposite directions, the material of the groove 175, which is thinner than the material of the first central part 177 and the second central part 179, may break, thereby releasing the first central part 177 from the second central part 179.

[0075] Fig. 6A shows the downhole packer assembly 101 in an intermediate operational state, where the patch 21 has been expanded by fluid pressure inside the first expandable tubular element 113 and the second expandable tubular element 117 and by fluid pressure inside the confined space 41 to a position where the patch 21 is in contact with the inner surface of a well tubular metal structure (not shown). In the intermediate operational state, the force shown by arrow Cl and the force shown by arrow C2, as seen in Fig. 6B, applied by the fluid pressure inside the confined space 41 are below the predefined fluid pressure required to break the breakable part 159, i.e. the weakness of the groove 175. When the fluid pressure inside the confined space 41 exceeds the predefined fluid pressure required to break the breakable part 159, the force shown by arrows Cl and C2 applied to the first expandable tubular element 113 and the second expandable tubular element 117 forces the first central part 177 and the second central part 179 in opposite directions, thereby allowing the downhole packer assembly 101 to move to its second operational state where the distance between the first expandable tubular element 113 and the second expandable tubular element 117 is increased by

[0076] P2864PC00 the movement of the first central part 177 and the second central part 179 away from each other, as seen in Fig. 6B.

[0077] The first central part 177 and the second central part 179 may be configured to slide along the mandrel 169 in a distance away from each other. When the breakable part 159 breaks, the pressure inside the confined space 41 may momentarily be reduced due to the increased volume of the confined space 41. The fluid communication channel 174 maintains the fluid pressure inside the first expandable tubular element 113 and the second expandable tubular element 117 to such a degree that the confined space 41 is isolated from the rest of the well, where the pump increases the fluid pressure inside the confined space 41 to ensure that the first expandable tubular element 113 and the second expandable tubular element 117 move a sufficient distance away from each other to expand the ends of the patch 21 (23, 25 as shown in Fig. 3B).

[0078] As seen in Fig. 5, the third fluid outlet 139 and the fourth fluid outlet 140 may comprise a first reduction valve 183, where the first reduction valve 183 ensures that the fluid pressure entering the third fluid outlet 139 and the fourth fluid outlet 140 is lower than the fluid pressure entering the first fluid outlet 131 and the second fluid outlet 133. The first reduction valve 183 may be configured to provide a pressure reduction of 30 bars, ensuring that the pressure inside the first expandable tubular element 113 and the second expandable tubular element 117 is at least 30 bars higher than the pressure inside the confined space 41 (as seen in Fig. 3B). This may ensure that the pressure inside the expandable tubular elements 113, 117 is higher than the pressure inside the confined space 41.

[0079] The embodiment shown in Figs. 4-6 is disclosed as having a third fluid outlet 139 and a fourth fluid outlet 140 for introducing pressurised fluid into the confined space 41. In an alternative embodiment, the central part 111 may have a fluid outlet arranged either in the first central part 177 or in the second central part 179. In another embodiment, the mandrel 169 may be provided with a third fluid outlet 185 having a third reduction valve, where the third fluid outlet 185 is exposed when the first central part 177 moves away from the second central part 179 and exposes the mandrel 169. The third fluid outlet 185 may be utilized to expand the confined space 41 when the breakable part 159 has broken, and the downhole packer assembly 101 is moving towards its second operational state.

[0080] P2864PC00 In the embodiments shown in Figs. 1-6, the third outlet may be provided with a first reduction valve 183 and / or a third reduction valve which may be configured to have a second reduction value, where the second reduction value may be configured to be activated when the downhole packer assembly 1 transitions from its first operational state towards its second operational state, where the second reduction value may be in the pressure range of 150 bars to 240 bars. This means that when the first expandable tubular element moves relative to the second expandable tubular element, or vice versa, it is ensured that the pressure inside the first expandable tubular element and the second expandable tubular element is pressurized at a value that is in the range of 150 bars to 240 bars higher than the pressure inside the confined space, ensuring that the first expandable tubular element and the second expandable tubular element maintain their seal and isolate the confined space when the downhole packer assembly 1 transitions from its first operational state to its second operational state.

[0081] The use of the terms "first", "second", "third" and "fourth", "primary", "secondary", "tertiary", etc., does not imply any particular order, but are included to identify individual elements. Moreover, the use of the terms "first", "second", "third" and "fourth", "primary", "secondary", "tertiary", etc., does not denote any order or importance, but rather the terms "first", "second", "third" and "fourth", "primary", "secondary", "tertiary", etc., are used to distinguish one element from another. Note that the words "first", "second", "third" and "fourth", "primary", "secondary", "tertiary", etc., are used here and elsewhere for labelling purposes only and are not intended to denote any specific spatial or temporal ordering.

[0082] Furthermore, the labelling of a first element does not imply the presence of a second element and vice versa.

[0083] It is to be noted that the word "comprising" does not necessarily exclude the presence of other elements or steps than those listed.

[0084] It is also to be noted that the words "a" or "an" preceding an element do not exclude the presence of a plurality of such elements.

[0085] It should further be noted that any reference signs do not limit the scope of the claims. Although features have been shown and described, it will be understood that they are not intended to limit the claimed invention, and it will be made obvious to those skilled in the art that various changes and modifications may be made without departing from

[0086] P2864PC00 the spirit and scope of the claimed invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense. The claimed invention is intended to cover all alternatives, modifications and equivalents.

[0087] By "fluid" or "well fluid" is meant any kind of fluid that may be present in oil or gas wells downhole, such as natural gas, oil, oil mud, crude oil, water, etc. By "gas" is meant any kind of gas composition present in a well, completion or open hole, and by "oil" is meant any kind of oil composition, such as crude oil, an oil-containing fluid, etc. Gas, oil and water fluids may thus all comprise other elements or substances than gas, oil and / or water, respectively.

[0088] By "annular barrier" is meant an annular barrier comprising a tubular metal part mounted as part of the well tubular metal structure and an expandable metal sleeve surrounding and connected to the tubular part defining an annular barrier space.

[0089] By "casing" or "well tubular metal structure" is meant any kind of pipe, tubing, tubular, liner, string, etc., used downhole in relation to oil or natural gas production.

[0090] In the event that the tool is not submersible all the way into the casing, a downhole tractor can be used to push the tool / downhole system all the way into position in the well. The downhole tractor may have projectable arms having wheels, wherein the wheels contact the inner surface of the casing for propelling the tractor and the tool forward in the casing. A downhole tractor is any kind of driving tool capable of pushing or pulling tools in a well downhole, such as a Well Tractor®.

[0091] Although the invention has been described above in connection with preferred embodiments of the invention, it will be evident to a person skilled in the art that several modifications are conceivable without departing from the invention as defined by the following claims.

[0092] P2864PC00

Claims

Claims1. A downhole packer assembly for expansion of a metal patch in a well downhole in a well tubular metal structure, comprising :- a body part having a longitudinal extension and a central part,- a first expandable tubular element surrounding the body part and being connected with the body part on one side of the central part and having a first outer face,- a second expandable tubular element surrounding the body part and being connected with the body part on an opposite side of the central part and having a second outer face, and- a metal patch having a first end, a second end, an inner face and an outer face configured to face and abut the well tubular metal structure and having a first predefined length, wherein the metal patch surrounds the first expandable tubular element and the second expandable tubular element, wherein the first expandable tubular element is arranged at a first distance from the second expandable tubular element in the longitudinal extension in a first operational state, and wherein the first expandable tubular element is arranged at a second distance from the second expandable tubular element in the longitudinal extension in a second operational state, where the second distance is longer than the first distance.

2. A downhole packer assembly in accordance with claim 1 wherein the body part comprises a first tubular part having a first end and a second end, and a second tubular part having a first end and a second end, where the second end of the first body part is arranged at a first distance from the first end of the second body part in the first operational state, and where the second end of the first body part is arranged at a second distance from the first end of the second body part in the second operational state.

3. A downhole packer assembly in accordance with any of the preceding claims wherein the position of the first expandable tubular element is secured at the first distance relative to the second expandable tubular element in the first operational state, and when an expansion fluid reaches a predefined pressure threshold, the expansion fluid imposes a force on the first expandable tubular element and / or the second expandable tubular element to release the first expandable tubular element and / or the second expandable tubular element relative to the second tubular element.P2864PC004. A downhole packer assembly in accordance with any of the preceding claims wherein, in a first operational state, the outer face of the first expandable tubular element and the outer face of the second expandable tubular element are in contact with the inner face of the metal patch, defining a centre volume.

5. A downhole packer assembly in accordance with any of the preceding claims, wherein the body part has a first fluid outlet in fluid communication with an expandable space of the first expandable tubular element and a second fluid outlet in fluid communication with an expandable space of the second expandable tubular element.

6. A downhole packer assembly in accordance with any of the preceding claims, wherein the body part has a third fluid outlet in fluid communication with a confined space defined by the first expandable tubular element, the second expandable tubular element and an inner face of the metal patch.

7. A downhole packer assembly in accordance with any of the preceding claims, wherein the third fluid outlet is positioned in the central part.

8. A downhole packer assembly in accordance with any of the preceding claims, wherein the third fluid outlet comprises a first pressure reduction valve having a first fluid pressure input and a first fluid pressure output, where the first fluid pressure output is lower than the first fluid pressure input.

9. A downhole packer assembly in accordance with any of the preceding claims, wherein the third fluid outlet comprises a second pressure-reduction valve having a second fluid pressure input and a second fluid pressure output, where the second fluid pressure output is lower than the first fluid pressure output.

10. A downhole packer assembly in accordance with any of the preceding claims, wherein the first fluid pressure output is at least 20 bars lower than the first fluid pressure input, preferably where the first fluid pressure output is 25 bars lower than the first fluid pressure input, and more preferably where the first fluid pressure output is 30 bars lower than the first fluid pressure input.

11. A downhole packer assembly in accordance with any of the preceding claims, wherein the first expandable tubular element is secured relative to the second expandable tubular element by an extension tubular having a first end connected to theP2864PC00first expandable tubular element and a second end, where the extension tubular is configured to elongate from a first length to a second length at a predefined force threshold in the confined space.

12. A downhole packer assembly in accordance with any of the preceding claims, wherein the first expandable tubular element is secured relative to the second expandable tubular element by a breakable tubular having a first end connected to the first expandable tubular element and a second end, where the extension tubular is configured to break at a predefined force threshold in the confined space and release the first expandable tubular element relative to the second expandable tubular element.

13. A downhole packer assembly in accordance with claim 11 or 12, wherein the predefined force threshold is 150 bars of pressure in the confined space, more preferably the predefined force threshold is 180 bars of pressure in the confined space, and more preferably the predefined threshold is 200 bars of pressure in the confined space.P2864PC00

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