Composite flexible pipe and high-flexibility special-shaped section steel coiled tubing structure

Abstract

The invention discloses a composite flexible pipe and a high-flexibility special-shaped section steel continuous oil pipe structure, and relates to the technical field of oil and gas exploitation, the high-flexibility special-shaped section steel continuous oil pipe structure comprises an integrally seamless metal pipe body, and the metal pipe body continuously extends in the axial direction of the pipe body; protrusions distributed spirally are arranged on the outer wall of the metal pipe body in the axial direction, and the cross section of each protrusion comprises a non-circular symmetric or asymmetric geometrical shape. The coiled tubing structure has the advantages of high pressure bearing capacity, high flexibility and high friction clamping capacity on the premise of keeping continuity and coiling characteristics.

Description

Technical Field

[0001] This invention relates to the field of oil and gas extraction technology, and more specifically, to a highly flexible, irregularly shaped cross-section steel coiled tubing structure. Furthermore, it also relates to a composite flexible tubing comprising the aforementioned highly flexible, irregularly shaped cross-section steel coiled tubing structure. Background Technology

[0002] In existing technologies, coiled tubing is a long, coilable seamless steel pipe widely used in downhole operations, oil and gas extraction, acid fracturing, well washing, logging, and continuous injection. Existing coiled tubing typically uses a circular cross-section design, which is simple to manufacture, but has the following drawbacks:

[0003] 1. Limited pressure bearing capacity: Circular cross-section structures are prone to elliptic deformation or local buckling under external pressure; and in order to ensure the bending flexibility of the pipeline, the wall thickness usually needs to be reduced, which further weakens the strength and anti-collapse ability of the pipeline.

[0004] 2. Short bending fatigue life: In downhole operations, tubing needs to bend frequently to pass through wellhead equipment and guide wheels. However, traditional circular cross-sections have poor cross-sectional stability when bending, which easily leads to stress concentration and reduces fatigue life.

[0005] 3. Insufficient clamping force, prone to slippage: When coiled tubing is used downhole, force is transmitted through the drive wheel, clamp, or blowout preventer. Due to the small contact area and low coefficient of friction between the circular outer wall and the equipment, problems such as slippage, damage, or unstable clamping are prone to occur.

[0006] 4. Difficult to extend to composite structures: When used as the inner layer or pressure-bearing layer of flexible pipes or composite pipes, pipes with circular cross-sections are difficult to bond tightly with other structures, and are prone to interlayer slippage or debonding.

[0007] In summary, how to provide a continuous tubing structure that can maintain continuity and coilability while possessing high pressure resistance, high flexibility, and high friction clamping capacity is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0008] In view of this, the purpose of the present invention is to provide a highly flexible steel coiled tubing structure with irregular cross-section, which is a coiled tubing structure that can maintain continuity and coilability while possessing high pressure resistance, high flexibility and high friction clamping capacity.

[0009] Another objective of this invention is to provide a composite flexible pipe comprising the above-mentioned highly flexible irregular cross-section steel continuous tubing structure.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] A highly flexible, irregularly shaped cross-section steel continuous tubing structure includes an integral, seamless metal tube body that extends continuously along the tube body's axial direction. The outer wall of the metal tube body is provided with spirally distributed protrusions along the axial direction, and the cross-section of the protrusions includes non-circular symmetrical or asymmetrical geometric shapes.

[0012] In one embodiment, the cross-section of the protrusion includes a rectangular cross-section, a trapezoidal cross-section, a parallelogram cross-section, a triangular cross-section, or a semi-elliptical cross-section.

[0013] In one embodiment, when the cross-section of the protrusion is a rectangular cross-section, the aspect ratio of the rectangular cross-section is 0.15-0.5; when the cross-section of the protrusion is a semi-elliptical cross-section, the ratio of the minor axis to the major axis of the semi-elliptical cross-section is 0.2-0.6.

[0014] In one embodiment, a spirally distributed sealing groove is provided between two adjacent protrusions, and a sealing strip is embedded in the sealing groove.

[0015] A composite flexible tube includes, from the outside to the inside, an outer protective layer, an outer tensile layer, an outer wear-resistant layer, an inner tensile layer, an inner wear-resistant layer, a pressure-resistant armor layer, an inner liner, and a skeleton layer. The outer protective layer and the inner liner include cylindrical shell structures for achieving fluid sealing and isolation. The outer tensile layer and the inner tensile layer provide axial tensile force. The outer wear-resistant layer and the inner wear-resistant layer reduce friction between adjacent metal layers. At least one of the pressure-resistant armor layer and the skeleton layer is a high-flexibility irregular-section steel continuous tubing structure as described above, or the high-flexibility irregular-section steel continuous tubing structure is provided on the outside of the outer protective layer.

[0016] In one embodiment, the pressure-resistant armor layer includes an interlocking structure formed by spiral winding of stainless steel strips, the cross-section of which includes a Z-shaped cross-section, a C-shaped cross-section, or a T-shaped cross-section, and the skeleton layer is the highly flexible irregular cross-section steel continuous tubing structure.

[0017] In one embodiment, the skeleton layer includes an interlocking structure formed by spiral winding of stainless steel strip, the cross-section of the interlocking structure includes an S-shaped cross-section, and the pressure-resistant armor layer is the highly flexible irregular cross-section steel continuous tubing structure.

[0018] In one embodiment, both the pressure-resistant armor layer and the skeleton layer are interlocking structures formed by spiral winding of stainless steel strips. The cross-section of the interlocking structure of the pressure-resistant armor layer includes a Z-shaped cross-section, a C-shaped cross-section, or a T-shaped cross-section. The cross-section of the interlocking structure of the skeleton layer includes an S-shaped cross-section. The outer side of the outer protective layer is provided with the highly flexible irregular cross-section steel continuous tubing structure.

[0019] In one embodiment, both the pressure-resistant armor layer and the skeleton layer are the highly flexible irregular cross-section steel continuous tubing structure.

[0020] In one embodiment, the outer protective layer, the outer wear-resistant layer, the inner wear-resistant layer, and the inner liner all comprise polymer material components.

[0021] When using the highly flexible irregular cross-section steel coiled tubing structure provided by this invention, the highly flexible irregular cross-section steel coiled tubing structure is an integral seamless metal tube body, wherein the metal tube body extends continuously along the tube body axis, and the outer wall of the metal tube body is provided with spirally distributed protrusions along the axial direction. The cross-section of the protrusions includes non-circular symmetrical or asymmetrical geometric shapes. Since the cross-section of the protrusions on the outer wall of the metal tube body includes non-circular symmetrical or asymmetrical geometric shapes, the cross-sectional shape can be selected as rectangular, trapezoidal, parallelogram, triangular, semi-elliptical, or other symmetrical or asymmetrical geometric shapes with non-circular characteristics (that is, the outer contour of the metal tube body is a regular structure or an irregular structure), so that the highly flexible irregular cross-section steel coiled tubing structure forms a controllable strain distribution when bending, thereby improving circumferential stability and local buckling resistance, significantly improving the internal and external pressure bearing capacity of the device, and helping to extend the fatigue life of the device.

[0022] Furthermore, the regular or irregular outer contour of the metal tube increases the effective contact area and friction with the equipment, significantly improving the safety of the tubing during clamping and transport. In addition, this device can be used alone as a continuous tubing or as a pressure-bearing layer for traditional flexible metal tubing, in combination with polymer inner linings and outer protective layers, thus solving the problem of gaps in the pressure-bearing layer structure of traditional flexible metal tubing, which cannot withstand hydrostatic pressure independently.

[0023] In summary, the highly flexible irregular cross-section steel coiled tubing structure provided by this invention is a coiled tubing structure that can maintain continuity and coilability while possessing high pressure resistance, high flexibility, and high friction clamping capability.

[0024] In addition, the present invention also provides a composite flexible pipe including the above-mentioned highly flexible irregular cross-section steel continuous tubing structure. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0026] Figure 1This is a schematic diagram of the structure of a flexible metal tube in the prior art;

[0027] Figure 2 This is a schematic diagram of the structure of each layer of a flexible metal tube in the prior art;

[0028] Figure 3 This is a schematic diagram of the highly flexible irregular cross-section steel continuous tubing structure provided by the present invention;

[0029] Figure 4 A cross-sectional view of a highly flexible, irregularly shaped steel continuous tubing structure;

[0030] Figure 5 A schematic diagram of a rectangular cross-section of a highly flexible, irregularly shaped steel coiled tubing structure.

[0031] Figure 6 A schematic diagram of the cross-section of a highly flexible, irregularly shaped steel coiled tubing structure, showing a trapezoidal cross-section of the protrusion.

[0032] Figure 7 A schematic diagram of the cross-section of a protruding parallelogram in a highly flexible, irregularly shaped steel continuous tubing structure.

[0033] Figure 8 A schematic diagram of a triangular cross-section of a highly flexible, irregularly shaped steel coiled tubing structure.

[0034] Figure 9 A schematic diagram of the semi-elliptical cross-section of the protrusion of a highly flexible, irregularly shaped steel continuous tubing structure.

[0035] Figure 10 A schematic diagram of a Z-shaped cross-section for the compressive armor layer;

[0036] Figure 11 A schematic diagram of a C-shaped cross-section for the compressive armor layer;

[0037] Figure 12 A schematic diagram of a T-shaped cross-section for the compressive armor layer;

[0038] Figure 13 A schematic diagram showing another T-shaped cross-section for the compressive armor layer;

[0039] Figure 14 A schematic diagram of an S-shaped cross-section of the skeleton layer;

[0040] Figure 15 This is a schematic diagram of the first embodiment of the composite flexible tube provided by the present invention.

[0041] Figure 16 This is a schematic diagram of the layer structure of the first embodiment of the composite flexible tube;

[0042] Figure 17 This is a schematic diagram of a second embodiment of the composite flexible tube;

[0043] Figure 18 This is a schematic diagram of the layer structure of a second embodiment of the composite flexible tube;

[0044] Figure 19 A schematic diagram of the third embodiment of the composite flexible tube;

[0045] Figure 20 This is a schematic diagram of the layer structure of the third embodiment of the composite flexible tube.

[0046] Figures 1-20 middle:

[0047] 1 is the outer protective layer, 2 is the outer tensile layer, 3 is the outer wear-resistant layer, 4 is the inner tensile layer, 5 is the inner wear-resistant layer, 6 is the pressure-resistant armor layer, 7 is the inner liner, 8 is the skeleton layer, 9 is the high-flexibility irregular cross-section steel continuous tubing structure, and 91 is the protrusion. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] The core of this invention is to provide a highly flexible, irregularly shaped cross-section steel coiled tubing structure, which, while maintaining continuity and coilability, also possesses high pressure resistance, high flexibility, and high friction clamping capacity. Another core aspect of this invention is to provide a composite flexible tubing comprising the aforementioned highly flexible, irregularly shaped cross-section steel coiled tubing structure.

[0050] Please refer to Figure 3 and Figure 4 This specific embodiment provides a highly flexible irregular cross-section steel continuous tubing structure 9, including an integral seamless metal tube body that extends continuously along the tube body axis, and the outer wall of the metal tube body is provided with spirally distributed protrusions 91 along the axis. The cross-section of the protrusions 91 includes non-circular symmetrical or asymmetrical geometric shapes.

[0051] It should be noted that the metal tubing includes components made of alloy steel or stainless steel. Furthermore, by altering the cross-sectional curvature distribution and wall thickness, the circumferential stiffness and radial stability of the highly flexible, irregularly shaped cross-section steel coiled tubing structure 9 can be improved, thereby enhancing its ability to withstand internal and external pressure. Moreover, the protrusions 91 of the highly flexible, irregularly shaped cross-section steel coiled tubing structure 9 increase its effective contact area and friction with the equipment, significantly improving the safety of the tubing during clamping and transport. Furthermore, the cross-sectional shape of the highly flexible, irregularly shaped cross-section steel coiled tubing structure 9 is adjustable, and the protrusions 91 have a three-dimensional helical structure, allowing for a controllable strain distribution when the tubing bends, reducing stress concentration and extending fatigue life.

[0052] In practical applications, the shape, size, and material of the metal tube can be determined according to the actual situation and needs.

[0053] When using the highly flexible irregular cross-section steel coiled tubing structure 9 provided by this invention, the highly flexible irregular cross-section steel coiled tubing structure 9 is an integral seamless metal tube body, wherein the metal tube body extends continuously along the tube body axis, and the outer wall of the metal tube body is provided with spirally distributed protrusions 91 along the axial direction. The cross-section of the protrusions 91 includes non-circular symmetrical or asymmetrical geometric shapes. Since the cross-section of the protrusions 91 on the outer wall of the metal tube body includes non-circular symmetrical or asymmetrical geometric shapes, the cross-sectional shape can be selected as rectangular, trapezoidal, parallelogram, triangular, semi-elliptical, or other symmetrical or asymmetrical geometric shapes with non-circular characteristics (that is, the outer contour of the metal tube body is a regular structure or an irregular structure), so that the highly flexible irregular cross-section steel coiled tubing structure 9 forms a controllable strain distribution when bending, thereby improving circumferential stability and local buckling resistance, significantly improving the internal and external pressure bearing capacity of the device, and helping to extend the fatigue life of the device.

[0054] Furthermore, the regular or irregular outer contour of the metal tube increases the effective contact area and friction with the equipment, significantly improving the safety of the tubing during clamping and transport. In addition, this device can be used alone as a continuous tubing or as a pressure-bearing layer for traditional flexible metal tubing, in combination with polymer inner linings and outer protective layers, thus solving the problem of gaps in the pressure-bearing layer structure of traditional flexible metal tubing, which cannot withstand hydrostatic pressure independently.

[0055] In summary, the highly flexible irregular cross-section steel coiled tubing structure 9 provided by the present invention is a coiled tubing structure that can maintain continuity and coilability while possessing high pressure resistance, high flexibility and high friction clamping capability.

[0056] In one embodiment, the cross-section of the protrusion 91 includes a rectangular cross-section, a trapezoidal cross-section, a parallelogram cross-section, a triangular cross-section, or a semi-elliptical cross-section. When the cross-section of the protrusion 91 is a rectangular cross-section, the structure is as follows: Figure 5 As shown, when the cross-section of protrusion 91 is trapezoidal, the structure is as follows: Figure 6 As shown, when the cross-section of protrusion 91 is a parallelogram, the structure is as follows: Figure 7 As shown, when the cross-section of protrusion 91 is triangular, the structure is as follows: Figure 8 As shown, when the cross-section of protrusion 91 is a semi-elliptical cross-section, the structure is as follows: Figure 9 As shown, R1 is the lower arc transition dimension, R2 is the upper arc transition dimension, b1 is the upper width of protrusion 91, b2 is the distance between two adjacent protrusions 91, t is the thinnest wall thickness dimension, and h is the distance between protrusion 91 and the thinnest wall surface.

[0057] In one embodiment, when the cross-section of the protrusion 91 is a rectangular cross-section, the aspect ratio of the rectangular cross-section is 0.15-0.5; when the cross-section of the protrusion 91 is a semi-elliptical cross-section, the ratio of the minor axis to the major axis of the semi-elliptical cross-section is 0.2-0.6.

[0058] like Figure 3 As shown, the wall thickness of the highly flexible irregular-shaped steel coiled tubing structure 9 with a rectangular cross-section varies. By controlling the aspect ratio of the rectangular cross-section, the strain of the outer wall can be maintained continuously during bending, significantly extending fatigue life. Figure 4 As shown, the highly flexible, irregularly shaped cross-section steel coiled tubing structure 9 adopts a low-carbon steel integral seamless structure. The cross-sectional shape of the protrusion 91 can be set as a semi-ellipse, with the inner and outer wall thicknesses of the semi-elliptical cross-section gradually changing along the major axis of the ellipse, resulting in a uniform circumferential stress distribution. This tubing exhibits less deformation under both internal and external pressure conditions, demonstrating improved pressure resistance compared to traditional circular cross-section tubing. Figure 2 , Figure 4-14 , Figure 16 , Figure 18 as well as Figure 20 The image shows a magnified view of the protrusions 91 distributed circumferentially along the cross-section of the metal tube. The straight line at the lower edge of the image is actually the inner wall of the pipe (i.e., an arc). By viewing the magnified view of the cross-section, the structural details of the cross-section of the protrusions 91 of the metal tube can be effectively displayed.

[0059] In one embodiment, a spirally distributed sealing groove is provided between two adjacent protrusions 91, and a sealing strip is embedded in the sealing groove. To improve the sealing performance between the highly flexible irregular cross-section steel continuous tubing structure 9 and the outer clamp, a sealing material such as rubber is provided in the sealing groove.

[0060] It should be noted that, depending on the process conditions and application requirements, the highly flexible irregular cross-section steel continuous tubing structure 9 of this application can be prepared by the following methods: 1. Integral forming method, that is, using hot rolling, cold drawing or hydraulic bulging process to form an integral irregular cross-section tubing body in one step. This method is suitable for mass production of standardized structures; 2. Welding forming method, that is, rolling metal strip into irregular shape and then welding it with high precision, and then obtaining a tubing body with high sealing performance and high strength after shaping and heat treatment; 3. Additive / spinning / explosive forming method, that is, for special cross-sections or thick-walled structures, using metal 3D printing, spinning or explosive forming and other processes to directly manufacture, to achieve high-precision control of complex irregular cross-sections.

[0061] Compared to existing circular cross-section coiled tubing, the irregular cross-section of this device improves circumferential stability and local buckling resistance, significantly enhancing its internal and external pressure bearing capacity. Furthermore, the irregular cross-section better distributes strain during bending, reducing fatigue crack initiation and extending service life. Additionally, the increased contact area between the irregular outer wall and equipment such as drive wheels and blowout preventers improves the coefficient of friction, effectively preventing slippage and damage. Moreover, this device can be used directly in coiled tubing systems or as a pressure-bearing layer in flexible metal tubing structures, achieving compatibility in both coiled tubing and flexible tubing scenarios. It overcomes the shortcomings of traditional flexible metal tubing pressure-bearing layers, which have gaps and cannot withstand hydrostatic pressure independently. Furthermore, this device can utilize existing tubing forming, welding, or spinning equipment, eliminating the need for disruptive new equipment and facilitating industrial implementation.

[0062] In addition to the aforementioned highly flexible irregular cross-section steel coiled tubing structure 9, this invention also provides a composite flexible tubing comprising the highly flexible irregular cross-section steel coiled tubing structure 9 disclosed in the above embodiments. This composite flexible tubing includes, from the outside to the inside, an outer protective layer 1, an outer tensile layer 2, an outer wear-resistant layer 3, an inner tensile layer 4, an inner wear-resistant layer 5, a pressure-resistant armor layer 6, an inner liner 7, and a skeleton layer 8. The outer protective layer 1 and the inner liner 7 include cylindrical shell structures for achieving fluid sealing and isolation. The outer tensile layer 2 and the inner tensile layer 4 are used for… To provide axial tensile force, the outer wear-resistant layer 3 and the inner wear-resistant layer 5 are used to reduce friction between adjacent metal layers. For example, the outer tensile layer 2 and the inner tensile layer 4 are spiral steel strips to provide axial tensile force. The outer wear-resistant layer 3 and the inner wear-resistant layer 5 are usually spirally wound from polymer material strips to reduce frictional wear between adjacent metal layers. At least one of the pressure-resistant armor layer 6 and the skeleton layer 8 is a highly flexible irregular cross-section steel continuous tubing structure 9 of any of the above, or a highly flexible irregular cross-section steel continuous tubing structure 9 is provided on the outer side of the outer protective layer 1.

[0063] It should be noted that the outer protective layer 1 and the inner liner 7 are cylindrical shell structures made of polymer material, and are used for fluid sealing and barrier. The outer tensile layer 2 and the inner tensile layer 4 are made of helically wound rectangular cross-section spiral steel strips, and are used to provide axial tensile force. The outer wear-resistant layer 3 and the inner wear-resistant layer 5 are made of helically wound polymer material strips, and are used to reduce wear caused by friction between adjacent metal layers.

[0064] The commonly used pressure-resistant armor layer 6 is an interlocking structure formed by spiral winding of stainless steel strips. Its function is to provide resistance to internal and external pressure in the pipeline. The pressure-resistant armor layer 6 typically adopts Z-shaped, C-shaped, T-shaped, or other cross-sectional forms, such as... Figures 10 to 13 As shown. The original common skeleton layer 8 is an interlocking structure formed by spiral winding of stainless steel strips. Its main function is to prevent the inner liner tube from collapsing, while also providing external pressure resistance. The skeleton layer usually adopts an S-shaped cross-section, such as... Figure 14 As shown. However, the original flexible tube (such as Figure 1 and Figure 2 The disadvantage of the skeleton layer 8 (as shown) is that there are gaps between the interlocking spiral steel strips, which cannot prevent liquid penetration and cannot withstand hydrostatic pressure. Therefore, the skeleton layer itself is immersed in the fluid inside the pipe and cannot provide internal pressure bearing capacity.

[0065] This application employs a highly flexible, irregularly shaped cross-section steel coiled tubing structure 9 to replace the traditional spiral interlocking skeleton layer 8 as the pressure-bearing layer of the flexible metal tubing. The highly flexible, irregularly shaped cross-section steel coiled tubing structure 9 achieves integrated sealing and pressure bearing. Unlike the skeleton layer 8, the highly flexible, irregularly shaped cross-section steel coiled tubing structure 9 has no gaps and can withstand both internal and external pressure. Figure 15 and Figure 16 If the inner liner 7 has cracks, the highly flexible, irregularly shaped cross-section steel continuous tubing structure 9 can independently withstand the internal pressure, and the liquid inside the pipe will not penetrate into the pipe wall.

[0066] Traditional flexible tubes (such as) Figure 1 and Figure 2 (As shown) If there is a crack in the outer protective layer 1, the liquid outside the pipe will seep into the pipe wall, causing the outer protective layer 1, outer tensile layer 2, outer wear-resistant layer 3, inner tensile layer 4, inner wear-resistant layer 5, and pressure-resistant armor layer 6 to be immersed in the liquid. Because the interlocking structure of the pressure-resistant armor layer 6 of a traditional flexible metal pipe has gaps, it cannot provide resistance to external pressure when immersed in the liquid, resulting in the external pressure acting directly on the inner liner pipe 7. Figure 17 and 18In this process, a high-flexibility, irregularly shaped steel continuous tubing structure 9 replaces the pressure-resistant armor layer 6 of the traditional metal flexible tubing. If there is a crack in the outer protective layer 1, the liquid outside the tubing can be blocked outside the high-flexibility, irregularly shaped steel continuous tubing structure 9. The high-flexibility, irregularly shaped steel continuous tubing structure 9 can resist external pressure.

[0067] In one embodiment, the pressure-resistant armor layer 6 includes an interlocking structure formed by spiral winding of stainless steel strips. The cross-section of the interlocking structure includes a Z-shaped, C-shaped, or T-shaped cross-section, and the skeleton layer 8 is replaced by a highly flexible, irregularly shaped steel continuous tubing structure 9. Figure 15 and Figure 16 As shown, a highly flexible, irregularly shaped steel coiled tubing structure 9 with an irregular cross-section replaces the traditional skeleton layer composed of helical interlocking bands to serve as the pressure-bearing layer of the flexible metal tubing. The highly flexible, irregularly shaped steel coiled tubing structure 9 achieves integrated sealing and pressure bearing.

[0068] In one embodiment, the skeleton layer 8 includes an interlocking structure formed by spiral winding of stainless steel strip, the cross-section of which includes an S-shaped cross-section, and the pressure-resistant armor layer 6 is replaced by a highly flexible irregular cross-section steel continuous tubing structure 9.

[0069] Traditional flexible tubes (such as) Figure 1 and Figure 2 As shown, if the inner liner 7 is damaged, the pressure-resistant armor layer 6 of the traditional flexible metal pipe will be immersed in the internal fluid, and the pipe will lose its internal pressure bearing capacity. Similarly, if the outer protective layer 1 is damaged, the pressure-resistant armor layer 6 of the traditional flexible metal pipe will be immersed in the external fluid, and the pressure-resistant armor layer will completely lose its external pressure bearing capacity. The inner liner 7 and the outer protective layer 1 are extruded from low-strength thermoplastic, making them susceptible to damage from external forces. Therefore, traditional flexible metal pipes (such as...) Figure 1 and Figure 2 The security of (as shown) is relatively weak.

[0070] like Figure 17 and Figure 18 As shown, a highly flexible, irregularly shaped cross-section steel coiled tubing structure 9 replaces the traditional spiral interlocking band as the pressure-resistant armor layer 6 of the flexible metal tubing, achieving integrated sealing and pressure bearing. If the outer protective layer 1 is damaged, the highly flexible, irregularly shaped cross-section steel coiled tubing structure 9 can block external fluids and resist external pressure. Similarly, if the inner liner 7 is damaged, the highly flexible, irregularly shaped cross-section steel coiled tubing structure 9 can block internal fluids and resist internal pressure.

[0071] In one embodiment, both the pressure-resistant armor layer 6 and the skeleton layer 8 are interlocking structures formed by spiral winding of stainless steel strips. The cross-section of the interlocking structure of the pressure-resistant armor layer 6 includes a Z-shaped, C-shaped, or T-shaped cross-section, and the cross-section of the interlocking structure of the skeleton layer 8 includes an S-shaped cross-section. A highly flexible, irregularly shaped steel continuous tubing structure 9 is provided on the outside of the outer protective layer 1. That is, the highly flexible, irregularly shaped steel continuous tubing structure 9 is set on the outside of the outer protective layer 1 of the traditional flexible tubing, improving the pressure resistance and clamping force of the flexible tubing.

[0072] like Figure 19 and Figure 20 As shown, the highly flexible, irregularly shaped cross-section steel coiled tubing structure 9 is positioned outside the outer protective layer 1 of the traditional flexible tubing, allowing it to directly withstand external pressure on the pipeline. Simultaneously, it significantly improves the contact force between construction equipment (such as the tensioner of a pipelaying vessel, downhole equipment for wellhead operations, etc.) and the pipeline, preventing slippage during construction. Furthermore, when the flexible tubing is used as oil tubing, the highly flexible, irregularly shaped cross-section steel coiled tubing structure 9 on the outside of the pipeline can cooperate with a wellhead blowout preventer (BOP). In the event of an emergency, the BOP can lock the flexible tubing in place, preventing a blowout.

[0073] In one embodiment, both the pressure-resistant armor layer 6 and the skeleton layer 8 are highly flexible, irregularly shaped steel coiled tubing structures 9. The placement of the highly flexible, irregularly shaped steel coiled tubing structure 9 can be selected according to different application requirements. For example, the highly flexible, irregularly shaped steel coiled tubing structure 9 can be simultaneously arranged inside the inner liner 7 and outside the outer protective layer 1.

[0074] In one embodiment, the outer protective layer 1, the outer wear-resistant layer 3, the inner wear-resistant layer 5, and the inner liner tube 7 all comprise polymer material components.

[0075] In addition, it should be noted that the orientation or positional relationship indicated by terms such as "inside and outside" in this application is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the purpose of simplifying the description and making it easier to understand, and is not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0076] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. Any combination of all embodiments provided by this invention is within the scope of protection of this invention and will not be elaborated upon here.

[0077] The composite flexible tube and highly flexible irregular cross-section steel coiled tubing structure provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make several improvements and modifications to this invention without departing from the principles of this invention, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A highly flexible, irregularly shaped cross-section steel continuous tubing structure, characterized in that, It includes a seamless metal tube that extends continuously along the tube's axial direction, and the outer wall of the metal tube is provided with spirally distributed protrusions (91) along the axial direction. The cross-section of the protrusions (91) includes a non-circular symmetrical or asymmetrical geometric shape.

2. The highly flexible irregular cross-section steel continuous tubing structure according to claim 1, characterized in that, The cross-section of the protrusion (91) includes a rectangular cross-section, a trapezoidal cross-section, a parallelogram cross-section, a triangular cross-section, or a semi-elliptical cross-section.

3. The highly flexible irregular cross-section steel continuous tubing structure according to claim 2, characterized in that, When the cross-section of the protrusion (91) is a rectangular cross-section, the height-to-width ratio of the rectangular cross-section is 0.15-0.

5. When the cross-section of the protrusion (91) is a semi-elliptical cross-section, the ratio of the minor axis to the major axis of the semi-elliptical cross-section is 0.2-0.

6.

4. The highly flexible irregular cross-section steel continuous tubing structure according to any one of claims 1 to 3, characterized in that, A spirally distributed sealing groove is provided between two adjacent protrusions (91), and a sealing strip is embedded in the sealing groove.

5. A composite flexible pipe, characterized in that, The structure comprises, from the outside to the inside, an outer protective layer (1), an outer tensile layer (2), an outer wear-resistant layer (3), an inner tensile layer (4), an inner wear-resistant layer (5), a pressure-resistant armor layer (6), an inner liner (7), and a skeleton layer (8). The outer protective layer (1) and the inner liner (7) include cylindrical shell structures for achieving fluid sealing and isolation. The outer tensile layer (2) and the inner tensile layer (4) are used to provide axial tensile force. The outer wear-resistant layer (3) and the inner wear-resistant layer (5) are used to reduce friction between adjacent metal layers. At least one of the pressure-resistant armor layer (6) and the skeleton layer (8) is a high-flexibility irregular cross-section steel continuous tubing structure (9) as described in any one of claims 1 to 4, or the high-flexibility irregular cross-section steel continuous tubing structure (9) is provided on the outside of the outer protective layer (1).

6. The composite flexible tube according to claim 5, characterized in that, The pressure-resistant armor layer (6) includes an interlocking structure formed by spiral winding of stainless steel strips. The cross-section of the interlocking structure includes a Z-shaped cross-section, a C-shaped cross-section, or a T-shaped cross-section. The skeleton layer (8) is the highly flexible irregular cross-section steel continuous tubing structure (9).

7. The composite flexible tube according to claim 5, characterized in that, The skeleton layer (8) includes an interlocking structure formed by spiral winding of stainless steel strips. The cross-section of the interlocking structure includes an S-shaped cross-section. The pressure-resistant armor layer (6) is the highly flexible irregular cross-section steel continuous tubing structure (9).

8. The composite flexible tube according to claim 5, characterized in that, The pressure-resistant armor layer (6) and the skeleton layer (8) are both interlocking structures formed by spiral winding of stainless steel strips. The cross-section of the interlocking structure of the pressure-resistant armor layer (6) includes a Z-shaped cross-section, a C-shaped cross-section or a T-shaped cross-section. The cross-section of the interlocking structure of the skeleton layer (8) includes an S-shaped cross-section. The outer protective layer (1) is provided with the high-flexibility irregular cross-section steel continuous tubing structure (9).

9. The composite flexible tube according to claim 5, characterized in that, The pressure-resistant armor layer (6) and the skeleton layer (8) are both the highly flexible irregular cross-section steel continuous tubing structure (9).

10. The composite flexible tube according to any one of claims 5 to 9, characterized in that, The outer protective layer (1), the outer wear-resistant layer (3), the inner wear-resistant layer (5), and the inner liner (7) all consist of polymer material components.

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