DOWNHOLE EXPANDABLE TUBULAR ASSEMBLY

Abstract

 The present invention relates to a downhole expandable tubular assembly, such as a patch, having a longitudinal axis, to be expanded in a well downhole to abut an inner face of a casing or a borehole, the downhole expandable tubular assembly having an unexpanded condition and an expanded condition, and comprising a tubular part comprising an outer face and an inner face, and a sealing arrangement comprising a sealing compound arranged on the outer face facing the inner face, wherein the sealing arrangement further comprises an expandable tubular network. The invention further relates to a downhole system comprising a setting tool supporting the downhole expandable tubular assembly.

Description

[0001] The present invention relates to a downhole expandable tubular assembly. The invention also relates to a downhole system comprising a setting tool supporting the downhole expandable tubular assembly.

[0002] Hydrocarbon-containing wells are often completed with a well tubular metal structure, such as a casing, in order to produce oil or gas. Over the years, such casing may be eroded, creating a dangerously weak section or an open section of the casing that needs to be sealed off. As the well is still producing, the sealing needs to provide as large an inner diameter as possible, and thus a thin patch is preferred rather than a straddle. The known methods of setting the patch inside the casing have been challenging as the patch is a thin metal tubular being expanded by means of a hydraulic, radially expandable packer forcing the patch to plastically deform, and sometimes when power is lost, the expansion of the patch is stopped prematurely. The insufficiently expanded patch may then be so plastically deformed as to strengthen the patch too much so that the packer is not able to continue the expansion once the power is back on, and then the section is not sealed off.

[0003] In order to seal properly against the casing, the patch is provided with external sealing elements; however, when run in hole (RIH) these sealing elements have a tendency to be ripped off or at least damaged as it is often not possible to avoid bumping against the projections in the well. Thus, some setting tools have been equipped with a slidable protection cover to cover and protect the patch during running of the patch in hole. However, such covers are a complex and expensive solution.

[0004] It is an object of the present invention to wholly or partly overcome the above disadvantages and drawbacks of the prior art. More specifically, it is an object to provide an improved downhole expandable tubular assembly that is expandable in a simple manner and not exposed to the risk of being only partly expanded due to a loss of power while still being able to seal in a narrow well tubular metal structure.

[0005] The above objects, together with numerous other objects, advantages and features, which will become evident from the below description, are accomplished by a solution in accordance with the present invention by a downhole expandable tubular assembly, such as a patch, having a longitudinal axis, to be expanded in a well downhole to abut an inner face of a casing or a borehole, the downhole expandable tubular assembly having an unexpanded condition and an expanded condition, and comprising:

• a tubular part comprising an outer face and an inner face, and
• a sealing arrangement comprising a sealing compound arranged on the outer face facing the inner face,

wherein the sealing arrangement further comprises an expandable tubular network.

[0006] The expandable tubular network is able to expand along with the tubular part of the downhole expandable tubular assembly without substantially changing position in relation to the tubular part to ensure that an even distribution of the sealing compound on the tubular part is maintained. Once the sealing compound is curing, the network is strengthening the sealing arrangement, thus significantly increasing the collapse rating of the downhole expandable tubular assembly. In that way, the downhole expandable tubular assembly can be made very thin while still being able to withstand the required pressure difference across the downhole expandable tubular assembly, and without significantly decreasing the inner diameter of the casing. Furthermore, the expandable tubular network is able to protect the sealing compound while run in hole (RIH) so that a protective cover on the setting tool is no longer needed. The setting tool can thus be made simpler and with a smaller outer diameter than when a cover is needed. Thus, the downhole expandable tubular assembly can be used in very small diameter casings.

[0007] Also, the downhole expandable tubular assembly may be a downhole expandable metal tubular assembly.

[0008] Moreover, the downhole expandable metal tubular assembly may be a patch, and thus a downhole expandable metal tubular patch.

[0009] Furthermore, the expandable tubular network may enclose/surround the tubular part.

[0010] In addition, the tubular part may be a tubular metal part.

[0011] Further, the expandable tubular network may have a first outer diameter in an unexpanded condition of the downhole expandable tubular assembly and a second outer diameter in an expanded condition of the downhole expandable tubular assembly, the second outer diameter being larger than the first outer diameter.

[0012] Also, the expandable tubular network may have a first length when having the first outer diameter and a second length when having the second outer diameter, the first length being longer than the second length.

[0013] Moreover, the expandable tubular network may comprise strands and/or fibres.

[0014] Being "expandable" means that the expandable tubular network is configured to expand from a first outer diameter to a larger second outer diameter without breaking the strands or fibres.

[0015] Furthermore, the expandable tubular network may comprise strands in the form of first strands having a first direction with a first angle in relation to the longitudinal axis and in the form of second strands having a second direction with a second angle in relation to the longitudinal axis.

[0016] In addition, the first strands and the second strands may be interlacing. In this way, the interlacing first and second strands can move in relation to each other when expanding to the larger second outer diameter without breaking the strands and/or fibres. The first and second strands may thus be of a non-elastic material, while the expandable tubular network remains expandable.

[0017] Further, the first angle may be 45-90°, and the second angle may be 0-45°.

[0018] Also, the first strands may have a first width.

[0019] Moreover, the first strands may have a first width along a circumference of the tubular part and perpendicularly to the longitudinal axis.

[0020] Furthermore, the second strands may have a second width.

[0021] In addition, the second strands may have a second width along a circumference of the tubular part and perpendicularly to the longitudinal axis.

[0022] Further, the first strands and/or the second strands may each comprise a bundle of fibres.

[0023] Also, the first strands and/or the second strands may be made of carbon fibre, graphite fibre or similar fibres, such as glass fibre, basalt fibre, nylon fibre or PTFE (polytetrafluorethylene) fibre.

[0024] Moreover, the second strands may comprise elastic strands.

[0025] Furthermore, the first strands and/or the second strands may be made at least partly of an electrically conductive material, such as copper or graphite.

[0026] In addition, the tubular part may be made of a metal sheet which is rolled, forming overlapping layers when seen along a radial direction perpendicular to the longitudinal axis.

[0027] Further, the tubular part may have at least two layers, and preferably at least three layers.

[0028] Also, the tubular part may be rolled from one metal sheet, forming at least three overlapping layers in the unexpanded condition of the downhole expandable tubular assembly when seen along a radial direction perpendicular to the longitudinal axis.

[0029] Moreover, the tubular part may be made of a sheet which is rolled, forming overlapping layers when seen along a radial direction perpendicular to the longitudinal axis.

[0030] Furthermore, the sheet may be made of polymer, metal, such as shape memory alloy (SMA), or spring steel, or similar material, or a combination thereof.

[0031] Also, an adhesive layer of an adhesive compound may be arranged between the layers, the adhesive layer having a second thickness which is smaller than the first thickness of the metal sheet in a radial direction perpendicular to the longitudinal axis.

[0032] In addition, the metal sheet may be a plate-shaped element which is flexible and resilient so that when rolled or curled up into the tubular shape of the tubular part, a force is created in the element to counteract the rolling, and once released, the plate-shaped element unrolls as much as possible by enlarging its outer diameter within the casing or borehole until the outer face of the downhole expandable tubular assembly rests against the inner face of the casing. The inherent force maintains the downhole expandable tubular assembly in abutment to the wall of the casing during the curing of the sealing compound and the adhesive compound. Most often, the sealing compound and the adhesive compound are not fully cured, but are still able to seal, maintain and strengthen the downhole expandable tubular assembly so as to both seal sufficiently against the casing and withstand the pressure differential.

[0033] Also, the metal sheet may have a first thickness of 0.2-0.8 mm in a radial direction perpendicular to the longitudinal axis.

[0034] In addition, the sealing compound may have a third thickness in a radial direction perpendicular to the longitudinal axis.

[0035] Furthermore, the expandable tubular network may at least partly comprise swellable material.

[0036] Also, the expandable tubular network may comprise strands of swellable material.

[0037] Moreover, the strands of swellable material may form third strands interlacing with the first and second strands.

[0038] In addition, the expandable tubular network may comprise O-rings of swellable material.

[0039] Further, the O-rings of swellable material and the strands may be interlacing.

[0040] The O-rings of swellable material in the expandable tubular network are able to maintain the sealing compound in its intended position also after curing and setting.

[0041] Furthermore, the swellable material may be swelling when interacting with water and/or hydrocarbon-containing fluid.

[0042] Also, the layers may have a thickness equal to the first thickness.

[0043] Moreover, the tubular part may have a fourth thickness being the smallest thickness in the radial direction perpendicular to the longitudinal axis.

[0044] Furthermore, the fourth thickness may be in the range of 0.20-3.00 mm.

[0045] In addition, the sealing compound and/or the adhesive compound may typically comprise at least one of: epoxy, glue, a thermoset adhesive, a single-component adhesive, a two-component adhesive, a heat-responsive adhesive, a combination thereof, or any other suitable compound.

[0046] The sealing compound and/or the adhesive compound may be configured to be activated, e.g. to cure and set, by a temperature in the well exceeding an activation temperature of the sealing compound and/or the adhesive compound. Accordingly, activation of the sealing compound and/or the adhesive compound may advantageously be delayed until the downhole expandable tubular assembly is brought into position at the part of the wall to be expanded, thus lining the casing or borehole. If the required environmental temperature is not high enough for the activation, an integrated heater device in the setting tool may be used to assist the setting or curing process.

[0047] Further, the sealing compound and/or the adhesive compound may comprise an incapsulated component which is released when the downhole expandable tubular assembly is expanded and presses against the inner face of the casing or borehole.

[0048] Also, the sealing compound may be a swellable material adapted to swell in response to the environment in the well.

[0049] Moreover, the sealing compound may be heat-setting.

[0050] Furthermore, the sealing compound may be hydrophilic.

[0051] In addition, the sealing compound may have a first viscosity in the unexpanded condition of the downhole expandable tubular assembly, and the adhesive compound may have a second viscosity in the unexpanded condition of the downhole expandable tubular assembly, the first viscosity being lower than the second viscosity.

[0052] Further, the sealing compound may have a first shore hardness in the cured and expanded condition of the downhole expandable tubular assembly, and the adhesive compound may have a second shore hardness in the cured and expanded condition of the downhole expandable tubular assembly, the first shore hardness being lower than the second shore hardness.

[0053] Also, the sealing compound may be curing or setting when exposed to the well fluid.

[0054] Moreover, the sealing compound may be curing or setting when exposed to the increased heat in the well.

[0055] Furthermore, the sealing compound may be curing or setting when exposed to heat from a heating device in a downhole tool.

[0056] In addition, the invention relates to a downhole system comprising a setting tool supporting the downhole expandable tubular assembly.

[0057] Further, the setting tool may have a slidable protective cover circumferenting the downhole expandable tubular assembly when running in hole (RIH).

[0058] Also, the setting tool of the downhole system may further comprise a heating device for increasing the temperature to activate the sealing compound and/or the adhesive compound.

[0059] Moreover, the downhole system may further comprise a driving unit/downhole tractor.

[0060] Furthermore, the setting tool may comprise an activation device electrically connected with the expandable tubular network for generating heat to at least the sealing compound.

[0061] In addition, the invention relates to a method of lining at least one part of an inner face of a well tubular metal structure, such as a casing or borehole, the method comprising:

• providing a downhole expandable tubular assembly by:
  • providing at least one sheet having a first face to be applied to the wall,
  • applying an adhesive compound to the first face,
  • rolling the at least one sheet so that at least three layers overlap with the adhesive compound in between, providing a tubular part with an outer face, and
  • applying a sealing compound of a sealing arrangement on the outer face,
• arranging an expandable tubular network of the sealing arrangement around the outer face,
• inserting the downhole expandable tubular assembly into the well tubular metal structure,
• allowing the inserted downhole expandable tubular assembly to partially uncurl or unroll inside the well tubular metal structure until abutting the inner face of the well tubular metal structure, and
• activating the adhesive compound and the sealing compound to secure the sheet in the expanded condition of the downhole expandable tubular assembly.

[0062] Further, the method may also comprise arranging the downhole expandable tubular assembly on a setting tool.

[0063] Also, the method may further comprise displacing a cover covering the downhole expandable tubular assembly for protection of the downhole expandable tubular assembly while running the tool in hole (RIH).

[0064] Moreover, the method may further comprise moving the setting tool out of the well tubular metal structure, leaving the downhole expandable tubular assembly in the casing or borehole.

[0065] Furthermore, the setting tool may comprise at least one centraliser or similar distance element so as to distance the setting tool and thus the downhole expandable tubular assembly from the wall of the casing or borehole.

[0066] In addition, the setting tool may be coverless.

[0067] Further, the downhole expandable tubular assembly may expand in the radial direction perpendicular to the longitudinal axis.

[0068] Also, the method may further comprise using a heating device of the setting tool to heat the downhole expandable tubular assembly in order to activate curing of the sealing compound and/or the adhesive compound so as to utilise the adhesive compound to secure the layers in place and to provide a sealing ability of the sealing compound against the wall of the casing or borehole.

[0069] Moreover, the overlapping layers of metal sheet and the cured adhesive compound in between the overlapping layers of metal sheet may provide a tubular laminate.

[0070] The tubular laminate forms a solid structure which is configured to withstand a pressure differential between an inside of the casing and an outside of the casing.

[0071] The downhole expandable tubular assembly typically forms a patch of an opening of a weak part of the casing, and thus the downhole expandable tubular assembly needs to withstand this pressure differential in order to provide a lasting lining or patching of the opening or the weak part. Other parts of the wall to be lined or patched may be a sliding or rotational sleeve, a valve, a sand screen, or another structure in the well.

[0072] Finally, the downhole expandable tubular assembly may have an unexpanded condition in which the tubular part has a first configuration and an expanded condition in which the tubular part has a second configuration. When allowing the inserted downhole expandable tubular assembly to partially uncurl or unroll, the tubular part changes from the first condition to the second condition, reducing the extent of the overlap between the overlapping layers.

[0073] 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:

Fig. 1 shows a cross-sectional view of a downhole expandable tubular assembly in a casing in a well,

Fig. 2 shows a perspective of another downhole expandable tubular assembly,

Fig. 3 shows a perspective of another downhole expandable tubular assembly,

Fig. 4 shows a cross-sectional view of the downhole expandable tubular assembly shown in Fig. 3,

Fig. 5 shows a perspective of yet another downhole expandable tubular assembly,

Fig. 6 shows a cross-sectional view of the downhole expandable tubular assembly shown in Fig. 5,

Fig. 7 shows a perspective of yet another downhole expandable tubular assembly,

Fig. 8 shows an enlarged view of an expandable tubular network of a downhole expandable tubular assembly,

Fig. 9 shows an enlarged view of another expandable tubular network, and

Fig. 10 shows an enlarged view of yet another expandable tubular network.

[0074] 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.

[0075] Fig. 1 shows a downhole expandable tubular assembly 1, such as a patch, for lining a well tubular metal structure, such as a casing. The downhole expandable tubular assembly 1 has a longitudinal axis L and is expanded in a well 2 downhole to abut an inner face 3 of a casing 5 or expanded directly in a borehole 4 for closing off a low-pressure zone. The downhole expandable tubular assembly 1 is shown in an expanded condition, and before expansion it has an unexpanded condition, which is illustrated by dotted lines. The downhole expandable tubular assembly 1 comprises a tubular part 6 comprising an outer face 7 and an inner face 8, and a sealing arrangement 9 comprising a sealing compound 10 arranged on the outer face 7 facing the inner face 8. The sealing arrangement 9 further comprises an expandable tubular network 11. The expandable tubular network 11 encloses/surrounds the tubular part 6, and the tubular part 6 may be a tubular metal part. The expandable tubular network 11 has a first outer diameter OD₁ in an unexpanded condition of the downhole expandable tubular assembly 1 and a second outer diameter OD₂ in an expanded condition of the downhole expandable tubular assembly 1, where the second outer diameter OD₂ is larger than the first outer diameter OD₁. The expandable tubular network 11 thus expands along with the downhole expandable tubular assembly 1, and once the sealing compound 10 is curing the network, the sealing arrangement 9 is strengthened, thus increasing the collapse rating of the downhole expandable tubular assembly 1. In that way, the downhole expandable tubular assembly 1 can be made very thin while still being able to withstand the required pressure difference across the downhole expandable tubular assembly 1, and thus the downhole expandable tubular assembly 1 can also be used in very small diameter casings.

[0076] While expanding, the tubular part 6 shortens in length, and the expandable tubular network 11 has a first length along the longitudinal axis L when having the first outer diameter OD₁ and a second length when having the second outer diameter OD₂, and thus the first length is somewhat longer than the second length.

[0077] In Fig. 2, the expandable tubular network 11 is arranged on an outside of the sealing compound 10 and thus protects the sealing compound 10 as the downhole expandable tubular assembly 1 is run in hole (RIH) so that a protective cover is no longer needed. Furthermore, the expandable tubular network 11 ensures that the even distribution of the sealing compound 10 around the outer face 7 of the tubular part 6 remains unchanged while the tubular part 6 is run in hole and while expanding so that the sealing arrangement 9 provides a sufficient seal between the tubular part 6 and the inner face 3 of the casing 5 along the entire outer face 7 of the downhole expandable tubular assembly 1. The expandable tubular network 11 is made of strands 14 as also shown in Fig. 8.

[0078] In Figs. 3 and 7, the expandable tubular network 11 is embedded in the sealing compound 10 so that it is not visible from the outside even though the expandable tubular network 11 still maintains an even distribution of the sealing compound 10 during expansion of the downhole expandable tubular assembly 1. Fig. 4 discloses a cross-sectional view of the downhole expandable tubular assembly 1 of Fig. 3 and thus illustrates that the tubular part 6 is made of metal.

[0079] The expandable tubular network 11 comprises strands 14 in the form of first strands 14A having a first direction 16 with a first angle α in relation to the longitudinal axis L, as shown in Fig. 9, and in the form of second strands 14B having a second direction 17 with a second angle β in relation to the longitudinal axis L. The first strands 14A and the second strands 14B are interlacing, e.g., forming a braded network which can expand as the tubular part 6 is expanding. In this way, the interlacing first and second strands 14, 14A, 14B can move in relation to each other when the downhole expandable tubular assembly 1 expands to the larger second outer diameter OD₂ without breaking the strands 14, 14A, 14B and/or fibres. The first and second strands 14, 14A, 14B may thus be of a non-elastic material, while the expandable tubular network 11 remains expandable. The first angle α is in the range of 35-90°, and the second angle β is in the range of 0-45°. In Fig. 9, the first angle α is close to 90°, and the second angle β is close to 0°. In Fig. 10, the first angle α is close to 40°, and the second angle β is close to 40°. The first strands 14A have a first width w₁ measured along the outer face 7. The second strands 14B have a second width w₂, and in Figs. 9 and 10 the first width w₁ is substantially the same as the second width w₂. In Fig. 8, the second strands 14B comprise elastic strands 15 to make the network expandable as the elastic strands 15 expand.

[0080] The first strands 14A and/or the second strands 14B are made of carbon fibre, graphite fibre or similar fibres, such as glass fibre, basalt fibre, nylon fibre or PTFE (polytetrafluorethylene) fibre. The fibres strengthen the sealing arrangement 9, while the network is still maintained expandable either by the interlacing pattern or the elastic strands 15. The first strands 14A and/or the second strands 14B may each comprise a bundle of fibres which flattens out along the outer face 7 of the tubular part 6, reducing the outer diameter OD₁ (shown in Fig. 1) of the downhole expandable tubular assembly 1 compared to a round strand, while still providing the same strength.

[0081] The first strands 14A and/or the second strands 14B may be made at least partly of an electrically conductive material, such as copper or graphite, so that some of the fibres are of electrically conductive material and others of strengthening fibres, such as carbon fibre, graphite fibre or similar fibres, such as glass fibre, basalt fibre, nylon fibre or PTFE (polytetrafluorethylene) fibre. If the strands 14, 14A, 14B are made of graphite, the strands 14, 14A, 14B can be made of only one material as graphite has both strengthening properties and is electrically conductive. In this way, the expandable tubular network 11 can be used to provide heat to the sealing arrangement 9 by providing electricity to the electrically conductive material. Thus, the setting tool for running the downhole expandable tubular assembly 1 in hole need not have a heating device, and the heat can be distributed quickly to the sealing compound 10 and directly to the position where needed as the strands 14, 14A, 14B are in direct contact with the sealing compound 10. In this way, less power is needed as less power is wasted to the surroundings, and the curing process is initiated earlier than if the heat were distributed from a heating device in the tool.

[0082] The expandable tubular network 11 may in one aspect at least partly comprise swellable material in order to provide a better seal as the swelling material will "fill out" any gaps between the downhole expandable tubular assembly 1 and the inner face of the well tubular metal structure when the swellable material is interacting with water and/or hydrocarbon-containing fluid. Thus, the expandable tubular network 11 may comprise strands of swellable material. The strands of swellable material can form third strands interlacing with the first and second strands 14, 14A, 14B. The expandable tubular network 11 may comprise O-rings of swellable material, and the O-rings of swellable material and the strands are interlacing. The O-rings of swellable material in the expandable tubular network 11 are also able to maintain the sealing compound 10 in its intended position after curing and setting.

[0083] In Fig. 5, the tubular part 6 is made of a metal sheet which is rolled, forming overlapping layers 12 when seen along a radial direction perpendicular to the longitudinal axis L. The tubular part 6 may have at least two layers 12, and preferably at least three layers 12. In Figs. 5 and 6, the tubular part 6 is rolled from one metal sheet, forming three overlapping layers 12 in the unexpanded condition of the downhole expandable tubular assembly 1 when seen along a radial direction perpendicular to the longitudinal axis L. In a section along the circumference of the tubular part 6, four layers are overlapping as the ends of the metal sheet overlap. The sheet may be made of polymer, metal, such as shape memory alloy (SMA), spring steel, or similar material, or a combination thereof.

[0084] The layers 12 may have a thickness equal to the first thickness ti, and as shown in Fig. 2 the tubular part 6 has a fourth thickness t₄ being the smallest thickness in the radial direction perpendicular to the longitudinal axis. The fourth thickness t₄ is in the range of 0.20-3.00 mm. Thus, in small diameter casings the inner diameter is merely decreased by 0.4 mm, which is substantially less than in many known solutions.

[0085] The metal sheet is a plate-shaped element being flexible and resilient so that when rolled or curled into the tubular shape of the tubular part 6, a force is created in the element, seeking to counteract the rolling, and once released, the plate-shaped element unrolls as much as possible by enlarging its outer diameter within the casing 5 or borehole 4 until the outer face 7 of the downhole expandable tubular assembly 1 rests against the inner face 3 of the casing 5. The inherent force maintains the downhole expandable tubular assembly 1 in abutment to the wall of the casing 5 during the curing of the sealing compound 10 and an adhesive compound 18 in between the layers. Most often, the sealing compound 10 and the adhesive compound 18 are not fully cured, but are still able to seal, maintain and strengthen the downhole expandable tubular assembly 1 so as to both seal sufficiently against the casing 5 and strengthen the sealing arrangement 9, increasing the collapse rating, i.e. the ability to withstand the pressure differential. A cross-sectional view of the tubular part 6 of the downhole expandable tubular assembly 1 of Fig. 5 is shown in Fig. 6, displaying that the metal sheet has a first thickness t₁ in the range of 0.2-0.8 mm in a radial direction perpendicular to the longitudinal axis L. Figs. 5 and 6 are made for illustrating the layers and the different features, for which reason Figs. 5 and 6 are not to scale as the first thickness t₁ in the range of 0.2-0.8 mm and the length of the downhole expandable tubular assembly 1 are at least 1 m in length along the longitudinal axis L. An adhesive layer of the adhesive compound 18 is arranged between the layers 12, and the adhesive layer has a second thickness t₂ which is smaller than the first thickness t₁ of the metal sheet in a radial direction perpendicular to the longitudinal axis L. The sealing compound 10 has a third thickness t₃ in a radial direction perpendicular to the longitudinal axis L.

[0086] Once the components of the adhesive compound 18 are fully mixed in, the mixture is spread over the sheet whilst still heated to above 50°C in liquid form and is left to cool down so that the mixture begins to "dry" and form a thin film of the adhesive compound 18 on the metal sheet. After rolling of the sheet, the sealing compound 10 is applied to the outer face 7. The sealing arrangement 9 intended to form a seal against the wall of the well tubular metal structure may typically have a thickness of approximately 1-3 mm.

[0087] When a setting tool 50 as shown in Fig. 1 is run into a wellbore, the temperature may typically increase to above 40°C, which will activate the sealing compound 10 and the adhesive compound 18. The sealing compound 10 and the adhesive compound 18 may be thermosetting adhesives. The sealing compound 10 and the adhesive compound 18 may, for example, comprise epoxy resin.

[0088] The sealing compound 10 and/or the adhesive compound 18 may typically comprise at least one of: epoxy, glue, a thermoset adhesive, a single-component adhesive, a two-component adhesive, a heat-responsive adhesive, a combination thereof, or any other suitable compound. The sealing compound 10 and/or the adhesive compound 18 may be configured to be activated, e.g. to initiate curing and setting, by a temperature in the well exceeding an activation temperature of the sealing compound 10 and/or the adhesive compound 18. The sealing compound 10 and/or the adhesive compound 18 may be configured to be activated at different temperatures to match the heat distribution so that the curing and setting are initiated at the same time. The sealing compound 10 and/or the adhesive compound 18 are/is designed so that the activation is delayed until the downhole expandable tubular assembly 1 is brought into position at the part of the wall to be expanded, thus lining the casing 5 or the borehole 4. If the required environmental temperature is not high enough for the activation of the curing process, the strands 14, 14A, 14B may, as mentioned above, comprise an electrically conductive material, or an integrated heater device in the setting tool may be used to assist the setting and curing process. Thus, the sealing compound 10 starts curing and setting when exposed to the increased heat in the well, and thus the sealing compound 10 may be heat-setting.

[0089] The sealing compound 10 and/or the adhesive compound 18 may comprise an incapsulated component which is released into a second component for a chemical reaction when the downhole expandable tubular assembly 1 is expanded and presses against the inner face 3 of the casing 5 or the borehole 4. The sealing compound 10 may in another aspect comprise a swellable material adapted to swell in response to the environment in the well. The sealing compound 10 may be curing and/or setting when exposed to the well fluid. Thus, if the well fluid comprises water, the sealing compound 10 may be hydrophilic in order to swell. In another aspect, the sealing compound 10 has a first viscosity in the unexpanded condition of the downhole expandable tubular assembly 1, and the adhesive compound 18 has a second viscosity in the unexpanded condition of the downhole expandable tubular assembly 1, the first viscosity being lower than the second viscosity. The sealing compound 10 may have a first shore hardness (shore D) in the cured and expanded condition of the downhole expandable tubular assembly 1, and the adhesive compound 18 may have a second shore hardness (shore D) in the cured and expanded condition of the downhole expandable tubular assembly 1, the first shore hardness (shore D) being lower than the second shore hardness (shore D).

[0090] A downhole system 100 comprising the setting tool 50 supporting the downhole expandable tubular assembly 1 is shown in Fig. 1. The setting tool 50 comprises an activation device 51 electrically connected with the expandable tubular network 11 for generating heat to at least the sealing compound 10. In another aspect, the setting tool 50 of the downhole system 100 comprises a heating device for increasing the temperature to activate the sealing compound 10 and/or the adhesive compound 18. Even though not shown, the downhole system 100 may further comprise a driving unit/downhole tractor for propelling the setting tool 50 forward in the well. The setting tool 50 may also have a slidable protective cover circumferenting the downhole expandable tubular assembly 1 when running in hole.

[0091] The method of lining at least one part of an inner face of a well tubular metal structure, such as the casing 5 or the borehole 4, comprises providing the downhole expandable tubular assembly 1 by first providing at least one sheet having a first face to be applied to the wall, secondly applying the adhesive compound 18 to the first face, then rolling the at least one sheet so that at least three layers overlap with the adhesive compound 18 in between, providing the tubular part 6 with the outer face 7, and then applying the sealing compound 10 of the sealing arrangement 9 on the outer face 7. Next, the method comprises arranging the expandable tubular network 11 of the sealing arrangement 9 around the outer face 7, inserting the downhole expandable tubular assembly 1 into the well tubular metal structure, and then allowing the inserted downhole expandable tubular assembly 1 to partially uncurl or unroll inside the well tubular metal structure until abutting the inner face of the well tubular metal structure, and subsequently activating the adhesive compound 18 and the sealing compound 10 to secure the sheet in the expanded condition of the downhole expandable tubular assembly 1.

[0092] The method may further comprise arranging the downhole expandable tubular assembly 1 on the setting tool 50 before it is run in hole (RIH). When in place, the method may further comprise displacing a cover arranged for covering the downhole expandable tubular assembly 1 for protection of the downhole expandable tubular assembly 1 while running the tool in hole in order to allow the downhole expandable tubular assembly 1 to partially uncurl or unroll. The method may also comprise moving the setting tool 50 out of the well tubular metal structure, leaving the expanded downhole expandable tubular assembly 1 in the casing 5 or the borehole 4. Instead of the cover and in order to further protect the sealing compound 10, the setting tool 50 may comprise at least one centraliser or similar distance element to distance the setting tool 50 and thus the downhole expandable tubular assembly 1 from the wall of the casing 5 or the borehole 4.

[0093] Thus, the setting tool 50 may be coverless. Once the downhole expandable tubular assembly 1 is allowed to expand, the downhole expandable tubular assembly 1 expands in the radial direction perpendicular to the longitudinal axis L by at least partial unrolling of the sheet.

[0094] The overlapping layers of metal sheet and the cured adhesive compound 18 in between the overlapping layers of metal sheet may provide a tubular laminate. Once set and at least partly cured, the tubular laminate forms a solid structure which is configured to withstand a pressure differential between an inside of the casing 5 and an outside of the casing 5. The downhole expandable metal tubular assembly 1 typically forms a patch of an opening of a weak part of the casing 5, and thus the downhole expandable metal tubular assembly 1 needs to withstand this pressure differential in order to provide a lasting lining or patching of the opening or the weak part. Other parts of the wall to be lined or patched may be a sliding or rotational sleeve, a valve, a sand screen, or another structure in the well.

[0095] The downhole expandable metal tubular assembly 1 has an unexpanded condition in which the tubular part 6 has a first configuration and an expanded condition in which the tubular part 6 has a second configuration. When allowing the inserted downhole expandable tubular assembly 1 to partially uncurl or unroll, the tubular part 6 changes from the first condition to the second condition, reducing the extent of the overlap between the overlapping layers.

[0096] Either or both of a leading edge and a trailing edge of the sheet may have at least one uneven edge formation, such as prongs or teeth, e.g. formed by way of cutouts in the edge, flattened parts of the edge creating projecting tongues, or other suitable edge formation. The sheet having a pronged edge facilitates both rolling and curling up of the lining, and partial unrolling or uncurling of the sheet upon release without twisting or partly rotating the unrolling direction. In this way, crinkling of the sheet upon rolling or unrolling may be reduced or avoided. Thus, the uneven edge formation may facilitate even or uniform expansion of the rolled and/or curled sheet towards the wall of the well tubular metal structure upon release.

[0097] 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.

[0098] 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.

[0099] In the event that the tool is not submergible all the way into the casing, a downhole tractor can be used to push the tool 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^®.

[0100] 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.

Claims

1. A downhole expandable tubular assembly (1), such as a patch, having a longitudinal axis (L), to be expanded in a well (2) downhole to abut an inner face (3) of a casing (5) or a borehole (4), the downhole expandable tubular assembly having an unexpanded condition and an expanded condition, and comprising:

- a tubular part (6) comprising an outer face (7) and an inner face (8), and

- a sealing arrangement (9) comprising a sealing compound (10) arranged on the outer face facing the inner face (3),

wherein the sealing arrangement further comprises an expandable tubular network (11).

2. The downhole expandable tubular assembly according to claim 1, wherein the expandable tubular network has a first outer diameter (OD₁) in an unexpanded condition of the downhole expandable tubular assembly and a second outer diameter (OD₂) in an expanded condition of the downhole expandable tubular assembly, the second outer diameter being larger than the first outer diameter.

3. The downhole expandable tubular assembly according to claim 1 or 2, wherein the expandable tubular network comprises strands (14).

4. The downhole expandable tubular assembly according to any of the preceding claims, wherein the expandable tubular network comprises strands in the form of first strands (14A) having a first direction (16) with a first angle (α) in relation to the longitudinal axis and in the form of second strands (14B) having a second direction (17) with a second angle (β) in relation to the longitudinal axis.

5. The downhole expandable tubular assembly according to claim 4, wherein the first strands and the second strands are interlacing.

6. The downhole expandable tubular assembly according to claim 4 or 5, wherein the first angle (α) is 45-90°, and the second angle (β) is 0-45°.

7. The downhole expandable tubular assembly according to any of claims 4-6, wherein the first strands and/or the second strands are made of carbon fibre, graphite fibre or similar fibres, such as glass fibre, basalt fibre, nylon fibre or PTFE (polytetrafluorethylene) fibre.

8. The downhole expandable tubular assembly according to any of claims 4-7, wherein the second strands comprise elastic strands (15).

9. The downhole expandable tubular assembly according to any of claims 4-8, wherein the first strands and/or the second strands are made at least partly of an electrically conductive material, such as copper or graphite.

10. The downhole expandable tubular assembly according to any of the preceding claims, wherein the tubular part is made of a metal sheet which is rolled, forming overlapping layers (12) when seen along a radial direction perpendicular to the longitudinal axis.

11. The downhole expandable tubular assembly according to claim 10, wherein the metal sheet has a first thickness (ti) of 0.2-0.8 mm.

12. The downhole expandable tubular assembly according to claim 10 or 11, wherein an adhesive layer of adhesive compound is arranged between the layers, the adhesive layer having a second thickness (t₂) which is smaller than the first thickness of the metal sheet.

13. The downhole expandable tubular assembly according to any of the preceding claims, wherein the expandable tubular network comprises strands of swellable material.

14. Downhole system (100) comprising a setting tool (50) supporting the downhole expandable tubular assembly according to any of the preceding claims.

15. Downhole system according to claim 14, wherein the setting tool comprises an activation device (51) electrically connected with the expandable tubular network for generating heat to at least the sealing compound.

Drawing