Method of positioning a tubular element in a borehole

Abstract

Method of positioning a tubular element in a borehole, comprising steps of: - lining the borehole with the tubular element by bending the tubular element radially outward and in axially reverse direction so as to form an expanded tubular section extending around an unexpanded tubular section, and increasing the length of the expanded tubular section by pushing the unexpanded tubular section relative to the expanded tubular section further into the borehole; - positioning a pushing member inside the unexpanded tubular section; - forming a force coupling between the pushing member and the unexpanded tubular section; and - moving the pushing member further into the borehole; wherein the unexpanded tubular section moves with the pushing member further into the borehole to increase the length of the expanded tubular section.

Description

[0001] Title: Method of positioning a tubular element in a borehole

[0002] TECHNICAL FIELD

[0003] The aspects and embodiments thereof relate to radially expanding tubular elements in boreholes.

[0004] BACKGROUND

[0005] W02008006841 discloses a method of radially expanding a tubular element extending into a wellbore formed in an earth formation. The method comprises inducing the wall of the tubular element to bend radially outward and in axially reverse direction so as to form an expanded tubular section extending around a remaining tubular section of the tubular element, wherein said bending occurs in a bending zone of the tubular element. The method further comprises increasing the length of the expanded tubular section by inducing the bending zone to move in axial direction relative to the remaining tubular section. Said wall includes a material that is plastically deformed in the bending zone during the bending process so that the expanded tubular section retains an expanded shape as a result of said plastic deformation.

[0006] In a particular embodiment, W02008006841 suggest to anchor the expanded pipe section to the ground using a suitable anchoring device. A tractor device is arranged near the anchoring device, for pushing the unexpanded section further into the expanded section.

[0007] SUMMARY

[0008] It is an object to provide for faster, more economical and / or more convenient methods and / or devices for placing a tubular element in a borehole, in particular a radially expanded tubular element. In particular, it is an aim to provide for a faster, more economical and / or more convenient method of pushing an unexpanded section further into an expanded section of the tubular element.

[0009] It has been observed that as a borehole with one or more substantially horizontal section increases in length, a weight of the drill string increases as well. This increased weight may pose a limit on the potential horizontal length of the borehole. It is an object to increase the horizontal length over which a borehole can be formed, in particular through soft formation. Soft formation may comprise sand, mud, clay, loam, silt, or any other soft formation optionally combined with water, gases, organic matter, and / or any other matter, in any combination thereof. Soft formation may comprise loose particles, the dynamic behaviour of which may resemble that of a fluid. Contrary to hard formation, such as rock, soft formation is more prone to collapse when a hole is drilled through said soft formation, in particular for non-vertical sections of a borehole through soft formation. It is preferred to allow for boreholes with a horizontal length of over 500 metres, or even over 1 kilometre, over 2 kilometres, or even more than 10 kilometres to be formed through soft formation.

[0010] A first aspect provides a method of positioning a tubular element in a borehole, the method comprising steps of: lining the borehole with the tubular element by bending the tubular element radially outward and in axially reverse direction so as to form an expanded tubular section extending around an unexpanded tubular section, and increasing the length of the expanded tubular section by pushing the unexpanded tubular section relative to the expanded tubular section further into the borehole; positioning a pushing member inside the unexpanded tubular section; forming a force coupling between the pushing member and the unexpanded tubular section; and moving the pushing member further into the borehole; wherein the unexpanded tubular section moves with the pushing member further into the borehole to increase the length of the expanded tubular section.

[0011] The pushing member allows a decoupling between the force required to bend the tubular element radially outward and in axially reverse direction, and the pushing force required to push the unexpanded tubular section further into the borehole. The pushing force is now exerted on the pushing member, and transferred via the pushing member to the unexpanded tubular section - instead of being applied directly to a proximal end of the unexpanded tubular section for example using the tractor device of W02008006841.

[0012] Now that the pushing force can be indirectly applied to the tubular element, more options for the material of the tubular element can be envisioned. For example, any tubular element disclosed herein may consist of or comprise a polymer, such as polyethylene. Typically, such material would collapse under the pushing force required. However, with the separate pushing member, these materials can now be used for the tubular element. The pushing member typically comprises or consists of metal, such as steel.

[0013] When comparing a metal tubular element, such as a steel tubular element, to a polymer tubular element, such as a PE tubular element, it has been observed that an outer diameter of the expanded tubular section of the metal tubular element remains essentially the same, whereas an outer diameter of the expanded tubular section of the polymer tubular element reduces after having been formed. The reduction of outer diameter may even be such that an inner wall of the expanded tubular section contacts an outer wall of the unexpanded tubular section, causing a high degree of friction between the unexpanded tubular section and the expanded tubular section.

[0014] The reduction of the outer diameter of the expanded tubular element, in particular in case the tubular element consists of or comprises one or more polymers, such as polyethylene (PE), also reduces a size of the annulus between the inner wall of the expanded tubular section and the outer wall of the unexpanded tubular section. It has been observed that this size of the annulus, for example a radial thickness between the inner wall of the expanded tubular section and the outer wall of the unexpanded tubular section, may be increased by increasing a fluid pressure inside the annulus. In other words, the annulus may be inflated using fluid pressure. Inflation may cause the diameter of the unexpanded tubular section to be reduced and / or the diameter of the expanded tubular section to be increased.

[0015] The term fluid encompasses one or more gasses and / or one or more liquids. Optionally, one or more solids may also be present in the fluid. Fluid pressure can be built up in the annulus because the annulus is closed at the leading end of the tubular element, where a bending zone is present transitioning the tubular element from the unexpanded tubular section to the expanded tubular section. The leading end may also be referred to as a distal end relative to the entry of the borehole.

[0016] The pushing member may prevent the tubular element, in particular the unexpanded tubular section, from collapsing due to the increased fluid pressure in the annulus. The pushing member may also in use accommodate the drill string, and more in general protect the tubular element. The pushing member may even be used to transport one or more gases, liquids, such as water, oil or gas, or cables, such as electric cables and / or telecommunication cables.

[0017] The standard dimension ratio (SDR) of the tubular element is defined as the ratio between the outside diameter of the tubular element and the wall thickness of the tubular element. Preferably, the tubular element has an SDR above 13.6, for example between 17-21.

[0018] The method may comprise steps of at least partially releasing the force coupling between the pushing member and the unexpanded tubular section, and subsequently at least partially retracting the pushing member from the borehole, by which the pushing member moves relative to the unexpanded tubular section.

[0019] When the borehole extends further than a length of the pushing member, it may be preferred to perform subsequent steps of: 1) forming the force coupling between the pushing member and the unexpanded tubular section, 2) moving the pushing member further into the borehole, 3) at least partially releasing the force coupling between the pushing member and the unexpanded tubular section, and 4) at least partially retracting the pushing member from the borehole. As such, using a reciprocating motion of the pushing member, the borehole and tubular element can have a longer length that the length of the pushing member and the stroke of the pushing member.

[0020] For any embodiment disclosed herein, the method may further comprise drilling the borehole using a drill which is coupled to a drill string, wherein the drill string passes through the pushing member. Using the drill string, fluid and / or torque can be transferred to the drill. Preferably, the drill can be steered to adjust an orientation of the borehole relative to the horizon.

[0021] When a drill string is positioned in the pushing member, the drill string may become stuck inside the pushing member. When the pushing member is moveable relative to the drill string, a movement of the pushing member relative to the drill string can be used to dislodge the stuck drill string. The movement of the pushing member relative to the drill string may be a translation and / or a rotation. During the movement of the pushing member relative to the drill string, the drill string may remain stationary.

[0022] In particular when the force coupling between the pushing member and the unexpanded tubular section is at least partially released, the pushing member may be rotated about an axis parallel to an elongation direction of the pushing member.

[0023] The force coupling between the pushing member and the unexpanded tubular section may be formed by increasing a fluid pressure in an annulus between the unexpanded tubular section and the expanded tubular section. Additionally or alternatively, the force coupling between the pushing member and the unexpanded tubular section may be at least partially released by increasing a fluid pressure in an annular space between an outer surface of the pushing member and an inner surface of the unexpanded tubular section.

[0024] Using fluid pressure to control the force coupling between the pushing member and the unexpanded tubular section may be a convenient and / or cost-effective manner of controlling.

[0025] As a particular option applicable to any method using fluid pumped into the annular space between the pushing member and the unexpanded tubular section, fluid may be pumped into the annular space between the outer surface of the pushing member and the inner surface of the unexpanded tubular section while at least partially retracting the pushing member from the borehole. As such, any fluid leaking away may be replaced to maintain sufficient fluid pressure.

[0026] In general, any borehole described herein may have one or more vertical section, one or more horizontal section, one or more curved sections, in any combination thereof. However, it has been observed that the method according to the first aspect is particularly advantageous for boreholes of which at least part of the borehole is oriented substantially horizontally.

[0027] In general, any borehole described herein may pass through hard formation, soft formation, or any combination thereof, with any number of adjacent sections with alternatingly hard and soft formation.

[0028] In any method according to first aspect, but especially when the tubular element comprises or consists of polymer, it is envisioned to feed the unexpanded tubular section through a narrowing member to decrease an outer diameter of the unexpanded tubular section. Preferably, but not necessarily, the outer diameter of the unexpanded tubular section prior to being fed through the narrowing member corresponds approximately to an outer diameter of the expanded tubular section. The outer diameter of the unexpanded tubular section prior to being fed through the narrowing member may correspond approximately to an outer diameter of the expanded tubular section. Additionally or alternatively, the unexpanded tubular section may be heated prior to or while being fed through the narrowing member. After being heated, the unexpanded tubular section may be forcefully cooled.

[0029] In any method disclosed herein, the unexpanded tubular section may be formed in a continuous or a discontinuous process.

[0030] In any method disclosed herein, the borehole may have an entry point and an exit point at the Earth’s surface, and the tubular element as well as the pushing member may extend from the entry point to the exit point. In such embodiments, as an option, the pushing member may be a conduit, such as a pipe, for transporting one or more fluids and / or wires through, in particular for transporting hydrogen or hydrocarbons through.

[0031] A second aspect of the present disclosure provides an arrangement for positioning a pushing member and a tubular element in a borehole, the arrangement comprising a tubular element forming module for forming an unexpanded tubular section of the tubular element, a pushing member handling module for moving the pushing member into the borehole, and an anchor for fixating a position of an expanded tubular section of the tubular element.

[0032] The pushing member handling module may further be arranged for rotating the pushing member about its longitudinal axis.

[0033] Any arrangement may comprise a narrowing member arranged to decrease an outer diameter of the unexpanded tubular section passing through the narrowing member. When the arrangement comprises a heating unit, the narrowing member may be positioned upstream of the heating unit or aligned with the heating unit. It is preferred that the part of the unexpanded tubular section passing through the narrowing member is heated to a temperature above ambient temperature, for example between 80 and 250 degrees C, in particular between 120 and 200 degrees C.

[0034] In general, after the entire borehole has been formed, a length of the pushing member may substantially correspond to the length of the borehole. Any arrangement may comprise a pushing member forming module for forming at least part of the pushing member. As such, while forming the borehole, the length of the pushing member may be increased by forming additional length of pushing member by the pushing member forming module.

[0035] Any pushing member may be embodied as a hollow pipe, for example a metal hollow pipe. An inside of any hollow pipe may be coated, for example to protect the pipe from fluids transported through the pipe after the pipe has been placed in the borehole.

[0036] Any arrangement disclosed herein comprising a pushing member may further comprise an abutment at or near a distal end of the pushing member, which abutment has a larger outer diameter than the pushing member. The abutment may prevent the bending zone from moving past the distal end of the pushing member.

[0037] When the arrangement further comprises a steering member at a distal end of the pushing member, in use the pushing member may be steered. The steering member may be rotationally asymmetrical, and may be rotated about its longitudinal axis to steer.

[0038] For drilling the borehole, any arrangement disclosed herein may further comprise a drill connected at a distal end of a drill string, and a drilling module for supplying fluid and / or torque to the drill via the drill string, wherein the drill string passes through the pushing member.

[0039] In use, the arrangement may comprise the tubular element, which tubular element comprises an expanded tubular section connected to the anchor and an unexpanded tubular section, wherein the expanded tubular section and the unexpanded tubular section are connected via a bending zone in which the tubular element is bent radially outward and in axially reverse direction.

[0040] For supplying a fluid into an annulus between the unexpanded tubular section and the expanded tubular section, any arrangement disclosed herein may comprise a pumping device. Additionally or alternatively, a second pumping device may be comprised by the arrangement for supplying a fluid into an annular space between the pushing member and the unexpanded tubular section.

[0041] BRIEF DESCRIPTION OF THE FIGURES

[0042] In the figures,

[0043] Figs. 1A-1C show a schematic view of a section of borehole;

[0044] Figs. 2A and 2B show another example of the borehole; and

[0045] Figs. 3A-3B schematically depict embodiments of an arrangement for positioning a pushing member and a tubular element in a borehole.

[0046] DETAILED DESCRIPTION OF THE FIGURES

[0047] Figs. 1A-1C show a schematic view of a section of borehole 102, for example forming part of a well 100 or any other underground passage. The borehole 102 is in these figures depicted during a method of positioning a pipe 300 and a tubular element 200 in the borehole 102. The part of the Earth’s surface 104 through which the borehole 102 extends is schematically depicted, and shown hatched. It will be appreciated that the borehole 102 may extend through soft formation, hard formation, or a combination thereof.

[0048] Between the situations depicted in Figs. 1A and IB, a further part of the borehole 102 has been lined with the tubular element 200 by bending the tubular element 200 radially outward and in axially reverse direction. This bending forms an expanded tubular section 202 extending around an unexpanded tubular section 204. The length of the expanded tubular section 202 is increased by pushing the unexpanded tubular section 204 relative to the expanded tubular section 202 further into borehole 102. Between the situations depicted in Figs. 1A and IB, part of the unexpanded tubular section 204 has become expanded tubular section 202 after passing through the bending zone 206.

[0049] For pushing the unexpanded tubular section 204 relative to the expanded tubular section 202 further into borehole 102, a pushing member 300 is positioned inside the tubular element 200, in particular in the unexpanded tubular section 204. When the pushing member 300 is moved further into the borehole 102 by a distance 2d, the unexpanded tubular section 204 moves with the pushing member further into the borehole 102, and a further distance d of the borehole 102 is lined with the expanded tubular section 202. To allow the pushing member 300 to move the unexpanded tubular section 204, a force coupling is formed between the pushing member 300 and the unexpanded tubular section 204.

[0050] Between the situations depicted in Fig. IB and 1C, the pushing member 300 has been partially retracted from the bore hole 102, in particular by distance 2d or conceivably by any other distance. However, the tubular element 200 has substantially remained in place. To allow the movement of the pushing member 300 relative to the tubular element 200, the force coupling between the pushing member 300 and the unexpanded tubular section 204 has to be at least partially released. In general, the force coupling may be based on friction between an outer surface 302 of the pushing member 300 and an inner surface 208 of the unexpanded tubular section 204.

[0051] In Figs. 1A-1C, the pushing member 300 is depicted as a hollow pipe. It will however be understood that in any method disclosed herein, the pushing member 300 may be a solid pushing member, without a passage therethrough as with the pipe 300 depicted in Figs. 1A-1C. When the pushing member 300 is a hollow pipe, or any other body with a passage therethrough, for example a drilling string may pass through the pushing member 300. The drilling string may be used to drill the borehole 102. Figs. 2A and 2B show another example of the borehole 102, with the pushing member 300 at least partially inserted into the unexpanded section 204 of the tubular element 200. Fig. 2B shows a state wherein a force coupling is present between the pushing member 300 and the unexpanded tubular section 204, and Fig. 2A shows a state with an at least partially released force coupling between the pushing member 300 and the unexpanded tubular section 204.

[0052] In the state depicted in Fig. 2A, the pushing member 300 can be moved relative to the unexpanded tubular section 204, by virtue of the at least partially released force coupling between the pushing member 300 and the unexpanded tubular section 204. In the state depicted in Fig. 2B, the pushing member 300 can be used to move the unexpanded tubular section 204. For example, by moving the pushing member 300 further into the borehole 102, the unexpanded tubular section 204 can also be pushed further into the borehole 102. It will be appreciated that in the state of Fig. 2A the pushing member 300 may still contact part of the unexpanded tubular section 204.

[0053] Preferably, the force coupling between the pushing member 300 and the unexpanded tubular section 204 is based on a friction force between the outer surface 302 of the pushing member 300 and the inner surface 208 of the unexpanded tubular section 204. This friction force is based on a friction coefficient between the outer surface 302 of the pushing member 300 and the inner surface 208 of the unexpanded tubular section 204, and a force pushing the outer surface 302 of the pushing member 300 and the inner surface 208 of the unexpanded tubular section 204 towards one another.

[0054] In Fig. 2A, the friction force between the outer surface 302 of the pushing member 300 and the inner surface 208 of the unexpanded tubular section 204 - hereafter referred to as the friction force - is reduced by reducing the force pushing the outer surface 302 of the pushing member 300 and the inner surface 208 of the unexpanded tubular section 204 towards one another. In particular, an annular space 301 between the outer surface 302 of the pushing member 300 and the inner surface 208 of the unexpanded tubular section 204 is filled with a fluid.

[0055] To fill the annular space 301 between the outer surface 302 of the pushing member 300 and the inner surface 208 of the unexpanded tubular section 204 with a fluid, a pumping device 310 may be provided arranged to supply a flow of fluid 314 into the annular space 301. Optionally, a seal 316 and / or valve may be used to prevent the fluid from leaking out of the annular space 301. The seal 316 may be positioned between the outer surface 302 of the pushing member 300 and the inner surface 208 of the unexpanded tubular section 204.

[0056] In the situation depicted in Fig. 2B, a high friction force is preferred in order to have the force coupling between the pushing member 300 and the unexpanded tubular section 204, which in turn allows the unexpanded tubular section 204 to move further into the borehole 102 as the pushing member 300 moves further into the borehole 102.

[0057] To increase the friction force, the force pushing the outer surface 302 of the pushing member 300 and the inner surface 208 of the unexpanded tubular section 204 towards one another by increasing a fluid pressure inside an annulus 201 between the unexpanded tubular section 204 and the expanded tubular section 202. As the fluid pressure inside the annulus 201 is increased, the inner surface 208 of the unexpanded tubular section 204 can be forced against the outer surface 302 of the pushing member 300 with increased force.

[0058] To increase the fluid pressure inside the annulus 201, a pumping device 312 may be provided arranged for providing a flow of fluid 313 into the annulus 201. A seal 315 and / or valve may be positioned between the unexpanded tubular section 204 and the expanded tubular section 202 to prevent fluid leaking from the annulus 201.

[0059] In general, when the annulus 201 is filled with fluid, fluid 314 may be allowed to leak away from the annular space 301 between the outer surface 302 of the pushing member 300 and the inner surface 208 of the unexpanded tubular section 204. In the situation depicted in Fig. 2B, the annular space 301 is typically smaller than the annular space 301 in the situation depicted in Fig. 2B, and may even be essentially absent. Furthermore, in general, when the annular space 301 is filled with fluid, fluid 313 may be allowed to leak out of the annulus 201.

[0060] It has been observed that in the situation of Fig. 2A, when fluid is pumped into the annular space 301, fluid may leak between the unexpanded tubular section 204 and the pushing member 300 at a distal end 309 of the pushing member 300. As such, it may be preferred to keep pumping fluid into the annular space 301, for example while the pushing member 300 is retracted at least partially out of the borehole 201.

[0061] Fig. 3 A schematically depicts an embodiment of an arrangement 400 for positioning a pushing member 300 and a tubular element 200 in a borehole. For clarity and conciseness of the figure, the borehole is not depicted, but it will be appreciated that the expanded tubular section 202 depicted can be in a state of lining the borehole.

[0062] The arrangement 400 preferably comprises a drill 402, in use typically positioned downstream of the bending zone 206 of the tubular element. The drill 402 is connected to a drill string 404, which passes though the tubular element 200 and the pushing member 300. At an upstream end of the drill string 404, a drilling module 406 is provided. The drilling module 406 can be used to supply drilling fluid and / or torque to the drill 402 via the dill string. Optionally, the drilling module 406 may comprise a pipe handling module for connecting further segments to the drill string 404. Alternatively, drill string may for example be unwound from a coil.

[0063] The arrangement 400 further comprises a tubular element forming module 420, arranged for forming the unexpanded tubular section 204 of the tubular element 200. In the example of the arrangement 400 shown in Fig. 3A, but as an option applicable also to any other arrangement, the tubular element forming module 420 may be arranged for forming the unexpanded tubular section 204 in a generally continuous forming process, for example using extrusion and / or injection moulding. An infeed 422 for raw material for forming the tubular element 200 may be comprised by the tubular element forming module 420. When the tubular element comprises a polymer, the raw materials may be polymer particles.

[0064] To hold the expanded tubular section 202 in place, the arrangement 400 may comprise an anchor 410. The anchor 410 can fixate the expanded tubular section 202 relative to the fixed world, for example the surroundings of an entrance into the borehole. The anchor 410 is generally used to prevent the expanded tubular section 202 upstream of the bending zone from being moved into the borehole.

[0065] The arrangement 400 of Fig. 3 A further comprises a pushing member handling module 430. The pushing member handling module 430 may also be comprised by other embodiments of the arrangement disclosed herein, and is arranged to move the pushing member 300 into the borehole. When a method is preferred wherein the pushing member is further at least partially retracted from the borehole, the pushing member handling module 430 may be further arranged for retracting the pushing member 300 from the borehole. The pushing member handling module 430 may for example comprise one or more electric, pneumatic, and / or hydraulic actuators, such as one or more hydraulic cylinders.

[0066] As an option applicable to any pushing member handling module 430, the pushing member handling module 430 may further be arranged for rotating the pushing member 300 about its longitudinal axis.

[0067] Another option, applicable to any arrangement 400 disclosed herein, and depicted in Fig. 3 A, is that the arrangement 400 may comprise a heating unit 440 for heating the unexpanded tubular section 204 - in particular a section of the unexpanded tubular section 204 positioned outside the borehole. The heating unit 440 may further comprise a cooling unit for forcefully cooling the heated unexpanded tubular section 204, in order to cool the unexpanded tubular section 204 faster than when the heated unexpanded tubular section 204 would only be exposed to the ambient. Typically, the cooling unit is positioned downstream of where the unexpanded tubular section 204 is heated.

[0068] As depicted in Fig. 3A, the heating unit 440 may provide a tapered tunnel 442 through which the unexpanded tubular section 442 can be passed, for example after being formed using the tubular element forming module 420. The tapered tunnel is generally tapered towards the borehole 102, and allows the diameter of the unexpanded tubular section 442 to be reduced from a first diameter De* to a reduced second diameter Du. The tapered tunnel is thus an example of a narrowing member, and is also envisioned without the heating unit or with a separate heating unit. Typically, the second diameter Duis the diameter of the unexpanded tubular element 204. Preferably, the first diameter De* corresponds to the diameter Deof the expanded tubular section 202. However, for example depending on the material or materials used to form the tubular element 200, the first diameter De* can differ from the diameter De

[0069] By virtue of being able to heat the unexpanded tubular element 204 prior to or during the unexpanded tubular section 204 passing through the tapered tunnel 442, in particular when the tubular element 200 is formed from polymer material, the diameter Deof the expanded tubular element 202 may be controlled or at least partially tuned.

[0070] Fig. 3B shows part of an arrangement 400 for positioning a pushing member 300 and a tubular element 200 in a borehole 102. Fig. 3B shows a number of optional features which are applicable to any other embodiment of the arrangement 400 and methods disclosed herein.

[0071] In particular, the pushing member 300 is in Fig. 3B depicted comprising a steering member 303 positioned at a downstream end of the pushing member 300. From Fig. 3B, it will be appreciated that any pushing member 300 - with or without steering member 303 - may be partially positioned downstream of the bending zone 206. Using the steering member 303, the distal end of the pushing member 300 may be guided in a particular direction. For operating the steering member 303, a rotation of the pushing member 300 along its elongation axis may be used, for example applied using the pushing member handling module 430. The steering member 303 may be rotationally asymmetrical to allow for the steering by rotating the steering member 303 about the elongation axis of the pushing member 300.

[0072] Additionally or alternatively to a steering member 303, any pushing member 300 may be provided with an abutment 304 at or near the downstream end of the pushing member 300. The abutment 304 has a larger outer diameter than the pushing member 300 and / or a larger outer diameter than the diameter of the unexpanded tubular section 204. As such, the abutment 304 can prevent the bending zone 206 from moving past the abutment 304 and / or prevent the bending zone 206 from contacting the optional steering member 303.

[0073] As a further option for any arrangement 400 disclosed herein, Fig. 3B schematically depicts a pushing member forming module 450 arranged to form the pushing member 300. In general, the pushing member 300 may have a fixed length throughout any method of positioning a tubular element in a borehole, or the length of the pushing member 300 may be increased during any method of positioning a tubular element in a borehole. When the length of the pushing member 300 has to be increased, for example as the length of the borehole 102 increases, the pushing member forming module 450 may be used.

[0074] In general, the step of forming the pushing member 300 using the pushing member forming module 450 may be a continuous process, or a discrete process in which discrete segments of pushing member are connected to the existing pushing member 300. In an example of a continuous process, a sheet is folded into the shape of a tube and a seam is closed to form a closed tube as the pushing member 300.

[0075] It will be appreciated that any arrangement 400 disclosed herein may comprise one or more pumping devices, such as the pumping devices 310, 312 disclosed in conjunction with Figs. 2A-2B. As such, any arrangement 400 can be made to be able to supply a fluid into an annulus between the unexpanded tubular section and the expanded tubular section and / or to supply a fluid into an annular space between the pushing member and the unexpanded tubular section. These pumping devices are omitted in Figs. 3A- 3B for clarity of these figures, but may be readily present in the arrangements 400 shown in Figs. 3A-3B. Additionally, one or more of the seals 315, 316 and / or valves disclosed in conjunction with Figs. 2A-2B may be readily present in the arrangements 400 shown in Figs. 3A-3B.

[0076] In any method and arrangement disclosed herein, part of the pushing member may be positioned downstream of the tubular element, in particular downstream of the bending zone of the tubular element. Additionally, or alternatively, the pushing member extends through at least 25%, at least 50%, at least 75%, or even at least 90% of the length of the tubular element, at least at one instance in time during any method of the present disclosure.

Claims

Claims1. Method of positioning a tubular element in a borehole, the method comprising steps of: lining the borehole with the tubular element by bending the tubular element radially outward and in axially reverse direction so as to form an expanded tubular section extending around an unexpanded tubular section, and increasing the length of the expanded tubular section by pushing the unexpanded tubular section relative to the expanded tubular section further into the borehole; positioning a pushing member inside the unexpanded tubular section; forming a force coupling between the pushing member and the unexpanded tubular section; and moving the pushing member further into the borehole; wherein the unexpanded tubular section moves with the pushing member further into the borehole to increase the length of the expanded tubular section.

2. Method according to claim 1, further comprising: at least partially releasing the force coupling between the pushing member and the unexpanded tubular section; and at least partially retracting the pushing member from the borehole, by which the pushing member moves relative to the unexpanded tubular section.

3. Method according to any of the preceding claims, further comprising drilling the borehole using a drill which is coupled to a drill string, wherein the drill string passes through the pushing member.

4. Method according to any of the preceding claims, wherein the pushing member is rotated about an axis parallel to an elongation direction of the pushing member.

5. Method according to any of the preceding claims, wherein the force coupling between the pushing member and the unexpanded tubular section is formed by increasing a fluid pressure in an annulus between the unexpanded tubular section and the expanded tubular section.

6. Method according to any of the preceding claims 2-5, to the extent dependent on claim 2, wherein the force coupling between the pushing member and the unexpanded tubular section is at least partially released by increasing a fluid pressure in an annular space between an outer surface of the pushing member and an inner surface of the unexpanded tubular section.

7. Method according to any of the preceding claims, wherein fluid is introduced into an annular space between an outer surface of the pushing member and an inner surface of the unexpanded tubular section while at least partially retracting the pushing member from the borehole.

8. Method according to any of the preceding claims, wherein at least part of the borehole is oriented substantially horizontally.

9. Method according to any of the preceding claims, wherein a majority of the borehole passes through soft formation, such as sand, mud, clay, loam, and / or silt.

10. Method according to any of the preceding claims, wherein the tubular element comprises a polymer, such as polyethylene.

11. Method according to any of the preceding claims, wherein the pushing member comprises a metal, such as steel.

12. Method according to any of the preceding claims, further comprising feeding the unexpanded tubular section through a narrowing member to decrease an outer diameter of the unexpanded tubular section.

13. Method according to claim 12, wherein the outer diameter of the unexpanded tubular section prior to being fed through the narrowing member corresponds approximately to an outer diameter of the expanded tubular section.

14. Method according to any of the claims 11-13, wherein the unexpanded tubular section is heated prior to and / or while being fed through the narrowing member.

15. Method according to any of the preceding claims, wherein the unexpanded tubular section is formed in a continuous process.

16. Method according to any of the claims 1-14, wherein the unexpanded tubular section is formed in a discontinuous process, for example by mirror welding tubular sections together.

17. Method according to any of the preceding claims, wherein the borehole has an entry point and an exit point at the Earth’s surface, and the tubular element as well as the pushing member extend from the entry point to the exit point.

18. Method according to claim 17, wherein the pushing member is a conduit, such as a pipe, for transporting one or more fluids and / or wiresthrough, in particular for transporting water, salt water, hydrogen or hydrocarbons through.

19. Arrangement for positioning a pushing member and a tubular element in a borehole, the arrangement comprising: a tubular element forming module for forming an unexpanded tubular section of the tubular element; a pushing member handling module for moving the pushing member into the borehole; and an anchor for fixating a position of an expanded tubular section of the tubular element.

20. Arrangement according to claim 19, wherein the pushing member handling module is further arranged for rotating the pushing member about its longitudinal axis.

21. Arrangement according to any of the claims 19-20, further comprising a heating unit for heating the unexpanded tubular section of the tubular element.

22. Arrangement according to any of the claims 19-21, further comprising a narrowing member arranged to decrease an outer diameter of the unexpanded tubular section passing through the narrowing member.

23. Arrangement according to any of the claims 19-22, further comprising a pushing member forming module for forming at least part of the pushing member.

24. Arrangement according to any of the claims 19-23, further comprising a hollow pipe as the pushing member.

25. Arrangement according to any of the claims 19-24, further comprising an abutment at or near a distal end of the pushing member, which abutment has a larger outer diameter than the pushing member.

26. Arrangement according to any of the claims 19-25, further comprising a steering member at a distal end of the pushing member for steering the pushing member.

27. Arrangement according to any of the claims 19-26, further comprising a drill connected at a distal end of a drill string, and a drilling module for supplying fluid and / or torque to the drill via the drill string, wherein the drill string passes through the pushing member.

28. Arrangement according to any of the claims 19-27, further comprising the tubular element, which tubular element comprises an expanded tubular section connected to the anchor and an unexpanded tubular section, wherein the expanded tubular section and the unexpanded tubular section are connected via a bending zone in which the tubular element is bent radially outward and in axially reverse direction.

29. Arrangement according to any of the claims 19-28, further comprising a first pumping device for supplying a fluid into an annulus between the unexpanded tubular section and the expanded tubular section.

30. Arrangement according to any of the claims 19-29, further comprising a second pumping device for supplying a fluid into an annular space between the pushing member and the unexpanded tubular section.

31. Method according to claim 10, wherein the tubular element consists of polymer, such as polyethylene.

32. Method according to any of the claims 1-18 or 31, wherein part of the pushing member is positioned downstream of the tubular element, in particular downstream of a bending zone (206) of the tubular element.

33. Method according to any of the claims 1-18, or 31-32, wherein the pushing member extends through at least 50% of the length of the tubular element.

34. Method according to any of the claims 1-18, or 31-33, further comprising forming at least part of the pushing member in a continuous process or a discrete process in which discrete segments of pushing member are connected to the existing pushing member.

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