System for transporting offshore structures

Abstract

A system for transporting an offshore structure, comprising a transportation device, in particular a ship or vehicle, configured to receive the offshore structure and form a slip joint together with a slip joint portion of the received offshore structure, the system being configured to transition from a fixed state to a releasable state, in which a slip joint force of the slip joint formed between the transportation device and the offshore structure is smaller than the slip joint force in the fixed state.

Description

[Technical Field]

[0001] The present invention relates to a system for transporting offshore structures. [Background technology]

[0002] For example, marine structures may need to be transported from land to sea, or vice versa. A problem here is that the structures can be substantially large and heavy relative to the transportation device, e.g., the vessel transporting the structure. To ensure stable transportation, it is generally necessary to rigidly fasten or fasten the marine structure to the transportation device. This is particularly important when the center of gravity of the marine structure is significantly removed from the location where it is supported by the transportation device, such as when an offshore wind turbine is transported on a ship in an upright position. For example, after arriving at an offshore installation site, the marine structure needs to be released from the transportation device, which generally requires unfastening.

[0003] Known solutions for fastening offshore structures to transportation devices use numerous nuts and bolts to rigidly connect the offshore structure to the transportation device, but these nuts and bolts must later be removed to release the offshore structure. This makes receiving, fastening, and releasing very laborious and time-consuming. Furthermore, this solution requires the transportation device to be specially configured to accommodate the particular size and configuration of the offshore structure (including, for example, the locations of holes for the bolts). Summary of the Invention [Problem to be solved by the invention]

[0004] It is an object of the present invention to provide an improved system for transporting offshore structures, and in particular to solve at least one of the problems mentioned above. It is a further object of the present invention to provide an improved method for transporting offshore structures, an improved transport device, and an improved offshore structure. [Means for solving the problem]

[0005] An aspect of the invention provides a system for transporting a marine structure, which system is characterized by the features of claim 1.

[0006] The system comprises a transport device, in particular a vessel or vehicle, adapted to receive an offshore structure and to form a slip joint with a slip joint portion of the received offshore structure.

[0007] The system is configured to transition from a fixed state to a releasable state, and in the releasable state, the slip joint force of the slip joint formed between the transportation device and the offshore structure is smaller than the slip joint force in the fixed state.

[0008] The slip joint can provide a safe and efficient means for substantially quickly fastening the offshore structure to the transportation device. For example, the slip joint can be formed and / or maintained under the influence of the offshore structure's own weight. Furthermore, in this manner, offshore structures of various sizes can be interchangeably received on the transportation device without substantially requiring specific modifications to the transportation device. By being configured to transition to a releasable state, the system can provide a safe and efficient means for substantially quickly releasing the offshore structure from the transportation device.

[0009] According to one embodiment, in the fixed state the offshore structure is fixed to the transport device and in the releasable state the offshore structure is releasable from the transport device, for example using lifting means.

[0010] In this way, by transitioning the system from a fixed state to a releasable state, the marine structure can be transitioned from a state in which it is fixed to the transportation device (e.g., for stable and reliable transportation) to a releasable state (e.g., for installing the marine structure at its destination).

[0011] In one embodiment, the system further comprises a vibration generator for vibrating the transportation device and the offshore structure relative to each other, in particular for reducing slip joint forces.

[0012] It has been found that such vibration generators can be an effective means of reducing slip joint forces.

[0013] In one embodiment, the vibrations are generated substantially at one or more predetermined resonant frequencies.

[0014] Vibration at such frequencies has been found to be particularly effective in reducing slip joint forces.

[0015] In one embodiment, the system further includes a separation system 4 including, for example, one or more mechanical force generating devices (e.g., jacks) configured to apply a separation force between the offshore structure and the transportation device.

[0016] Such an isolation system may advantageously provide a means, complementary to, for example, a vibration generator, to assist in reducing slip joint forces, and to substantially isolate the offshore structure from the transport apparatus while the slip joint forces are being reduced. Isolating the offshore structure from the transport apparatus in this manner may help to prevent slip joint forces from increasing again after they have been reduced, for example under the influence of the offshore structure's own weight and / or in response to manipulation of the offshore structure, for example by a lifting means.

[0017] In one embodiment, the system, preferably the transport device, comprises, in addition to the slip joint, a clamping device for clamping the offshore structure and the transport device together.

[0018] Here, in the fixed state, the marine structure and the transportation device are substantially clamped to each other by the clamping device, as compared to the releasable state.

[0019] The clamping device is preferably configured to push, e.g. hydraulically, one or more, e.g. two, clamping elements in one or more respective clamping directions extending towards the transport device and / or the offshore structure.

[0020] Clamping devices can provide a complementary means for fastening and releasing marine structures efficiently and quickly.

[0021] In one embodiment, the transportation device and the offshore structure each include a respective inclined surface portion, preferably a mating surface, such as a conical or frusto-conical surface, configured to form the slip joint with each other, particularly when they are arranged in contact with each other.

[0022] Each such surface can provide an effective means for forming a slip joint. Furthermore, it can provide a means for interchangeably receiving offshore structures of various sizes on a transportation device without substantially requiring specific modifications to the transportation device. For example, various sizes of frustoconical surface portions of offshore structures can be received by lowering them to various heights on the frustoconical surface portion of the transportation device.

[0023] In one embodiment, the transport device is configured to receive the offshore structure in a receiving direction, in particular configured to form a slip joint together with the slip joint portion of the offshore structure, wherein the receiving direction substantially coincides with the direction of gravity acting on the offshore structure, in particular the receiving direction is substantially downward.

[0024] Advantageously, the slip joint can thus be formed and / or maintained under the influence of the offshore structure's own weight.

[0025] In one embodiment, the system further comprises a lifting device, such as a crane, configured to lift the offshore structure and preferably position it, in particular relative to the transport device and / or relative to another structure, such as a loading base structure and / or a destination base structure.

[0026] Such a lifting device may provide a means for releasing the offshore structure from the transport device, particularly when the system is in a releasable state. The same or a similar lifting device may be used to form the slip joint, for example, by lowering the offshore structure onto the transport device.

[0027] In one embodiment, the system is configured to transport an offshore structure from a load location, and the system further comprises a load location base structure, e.g., a foundation, at the load location, the load location base structure configured, e.g., to form a slip joint with the offshore structure.

[0028] The system is configured to transition from a load base fixed state to a load base releasable state, and is configured so that in the load base releasable state, the slip joint force of the slip joint formed between the load base structure and the marine structure is smaller than the slip joint force in the load base fixed state.

[0029] In this way, the offshore structure can be safely, efficiently, and quickly loaded at the loading site. For example, slip joints with the loading site base structure can be made and released in this way, as well as slip joints with the transport device.

[0030] In one embodiment, the system comprises a vibration generator for vibrating the load-carrying base structure and the offshore structure relative to one another, in particular for reducing slip joint forces in slip joints formed by these structures, wherein the vibrations are preferably generated substantially at one or more predetermined resonant frequencies.

[0031] Such a vibration generator may provide similar advantages (albeit with some differences) as compared to the vibration generator described above for vibrating a transportation device and an offshore structure relative to each other.

[0032] In one embodiment, the system further comprises a load-based separation system, including, for example, one or more mechanical force generating devices, configured to apply a separation force between the offshore structure and the load-based structure.

[0033] Such load-based separation systems may provide similar advantages (albeit with some differences) compared to the previously described separation systems for applying a separation force between an offshore structure and a transportation device. The separation force may be significantly less than the weight of the offshore structure, and may provide for at least partially reaching the releasable state of the offshore structure. Alternatively, the separation force may be equal to or greater than the weight of the offshore structure.

[0034] In one embodiment, the system is configured to transport the offshore structure to a destination, the system further comprising a destination base structure, e.g., a foundation, at the destination, the destination base structure configured to receive the offshore structure and form a slip joint with the slip joint portion of the offshore structure.

[0035] In this way, the offshore structure can be installed safely, efficiently, and quickly at the destination, for example, a slip joint with the destination base structure can be formed in this way as well as a slip joint with the transportation device.

[0036] In one embodiment, the transportation device 1 is configured to receive a plurality of offshore structures and form a respective slip joint with a slip joint portion of each of the received offshore structures.

[0037] The system is configured to transition from a respective fixed state to a respective releasable state for each received offshore structure, and in the releasable state, the slip joint force of the slip joint formed between the transportation device and the offshore structure is smaller than the slip joint force in the fixed state.

[0038] Such a system is advantageous in that multiple offshore structures can be transported simultaneously while still benefiting from the advantages described above.

[0039] In one embodiment, the offshore structure includes one or more wind power generating devices and / or one or more wind power generating components, such as piles and / or nacelles, and / or one or more multi-component offshore structures, such as jackets, tripods and / or topsides.

[0040] Furthermore, for example, in one embodiment, it is also possible to configure one offshore structure to be supported by a plurality of (e.g., two, three, four or more) slip joints. In this case, the system is preferably configured to transition from a fixed state to a releasable state, and in the releasable state, the slip joint force of each of the plurality of slip joints formed between the transportation device and the offshore structure is smaller than the respective slip joint force in the fixed state.

[0041] In one embodiment, the offshore structure has a mass greater than 50,000 kg or greater than 490,000 N.

[0042] Such a large mass is advantageous in that it helps form a slip joint under the influence of the offshore structure's own weight.

[0043] Another aspect of the invention provides a method for transporting an offshore structure, the method comprising receiving the offshore structure on a transport device and forming a slip joint between the transport device and the received offshore structure, the method further comprising reducing a slip joint force of the slip joint and releasing the offshore structure from the transport device after reducing the slip joint force.

[0044] It is preferred to understand that the slip joint is formed and / or maintained at least under the influence of the weight of the offshore structure.

[0045] Such a method can provide the advantages mentioned above.

[0046] In one embodiment, the method further comprises generating vibrations in the offshore structure and / or transportation device, preferably substantially at one or more predetermined resonant frequencies, thereby reducing slip joint forces in the slip joint.

[0047] In one embodiment, the method further includes applying a separation force between the offshore structure and the transportation device.

[0048] In one embodiment, the separation force is applied prior to generating the vibration.

[0049] This has been found to be effective in reducing slip joint forces due to vibration.

[0050] In one embodiment, the separation force is applied while generating vibrations.

[0051] In this way, the marine structure can be separated from the transportation device in a particularly stable and well-controlled manner.

[0052] In one embodiment, the method further includes measuring a displacement of the offshore structure relative to the transportation device and / or measuring a pressure between the offshore structure and the transportation device, and releasing the offshore structure from the transportation device in response to the measured displacement and / or pressure.

[0053] In this way, the offshore structure can be released from the transportation device smoothly, safely, and efficiently. For example, the offshore structure may be released after the displacement is measured to be greater than a predetermined threshold displacement and / or after the pressure is measured to be less than a predetermined threshold pressure.

[0054] In one embodiment, the method further comprises using active heave compensation, particularly during release.

[0055] It has been found that the transportation, and in particular the release, of offshore structures can be made more stable and / or better controlled through the use of active heave compensation.

[0056] Another aspect of the invention is a transport device, in particular a transport device of the system according to the invention, in particular a ship or a vehicle, which is configured to receive an offshore structure and to form a slip joint with the slip joint part of the received offshore structure.

[0057] Such a transport device can provide the above-mentioned advantages, particularly in combination with an offshore structure.

[0058] In one embodiment, the transport device comprises a vibration generating device for vibrating the transport device and the marine structure carried on the transport device relative to each other, in particular for reducing slip joint forces of the slip joints.

[0059] In one embodiment, the transportation device comprises a separation system including, for example, one or more force generating devices configured to apply a separation force between the offshore structure and the transportation device.

[0060] Another aspect of the invention is an offshore structure of the system of the invention, in particular comprising a wind power device and / or one or more wind power components and / or one or more multi-component offshore structures, the offshore structure having at least one slip joint configured to form a slip joint with a respective slip joint of a transport device, e.g. a transport device of the invention, in particular for securing the offshore structure to the transport device.

[0061] Such offshore structures, particularly in combination with transportation devices, can provide the advantages mentioned above.

[0062] In one embodiment, the offshore structure is provided with a vibration generator for vibrating the offshore structure and the transportation device carrying the offshore structure relative to each other, in particular for reducing slip joint forces in the slip joint.

[0063] In one embodiment, the offshore structure comprises a separation system including, for example, one or more mechanical force generating devices configured to apply a separation force between the transportation device and the offshore structure.

[0064] In the following description, the invention is further explained by means of exemplary embodiments and drawings. [Brief explanation of the drawings]

[0065] [Figure 1a] 1 illustrates a cross-sectional view of a system in one embodiment. [Figure 1b] 10 shows a cross-sectional view of a system in another embodiment. [Figure 2a] 1 is a cross-sectional view of an embodiment of a system including a lifting device, the lifting device being shown in a substantially unloaded state. [Figure 2b] FIG. 2b is a cross-sectional view of the system of FIG. 2a, showing the lifting device substantially in a loaded state; [Figure 2c] FIG. 2c is a cross-sectional view of the system of FIGS. 2a-2b, showing the offshore structure being lifted by the lifting device. [Figure 3a] 10 is a cross-sectional view of yet another embodiment of a system showing how the system includes a clamping device in addition to a slip joint. [Figure 3b] 10 is a cross-sectional view of yet another embodiment of the system, showing multiple offshore structures received on a transportation device. [Figure 4a] 1 is a cross-sectional view of a load-carrying base structure with an offshore structure installed thereon in one embodiment; [Figure 4b] 1 is a cross-sectional view of a destination base structure with an offshore structure installed thereon in one embodiment; [Figure 5] FIG. 1 is a perspective exploded view showing a slip joint portion of an offshore structure and a corresponding slip joint portion of a transportation device.

[0066] The drawings are schematic and in the drawings, like or corresponding elements are marked with like or corresponding reference symbols. DETAILED DESCRIPTION OF THE INVENTION

[0067] In this disclosure, slip joint should be understood to mean at least a joint between an offshore structure and a slip joint portion of a transportation device or offshore foundation that is formed and / or maintained under the influence of the weight of the offshore structure.

[0068] In the present disclosure, the slip joint is preferably provided between a lower end of the offshore structure, in particular a lower end forming a slip joint portion of the offshore structure, and a complementary slip joint portion of the transportation device or a complementary slip joint portion of the offshore foundation, in particular a complementary slip joint portion of the upper end of the offshore foundation.

[0069] In the present disclosure, a slip joint may comprise an upper end of a slip joint portion of a transportation device or offshore foundation having at least one inclined surface and a lower end of an offshore structure having a complementary inclined surface, such that the inclined surfaces meet when the offshore structure is attached to the transportation device or offshore foundation, where inclined should be understood as being inclined at least relative to the vertical or the axis of the slip joint portion.

[0070] In one embodiment, the inclined surface may be formed by or as part of a conical or frustoconical surface of the offshore structure and the slip joint of the transportation device and offshore foundation, and the inclined surface is preferably provided so that the weight of the offshore structure further presses the offshore structure against the slip joint of the transportation device or offshore foundation, thereby securing it in place.

[0071] A slip joint according to the present disclosure may be, for example, but not limited to, a slip joint according to WO 2018 / 070868.

[0072] FIG. 1a shows a system for transporting an offshore structure according to an embodiment. The system comprises a transport device 1, particularly a vessel or vehicle, configured to receive an offshore structure 2 and form a slip joint JT with a slip joint portion 9 (see FIGS. 2c and 5) of the received offshore structure 2. In this example, a single slip joint JT is formed between the transport device 1 and the slip joint portion 9 of the offshore structure 2. Alternatively, the transport device 1 and the offshore structure 2 can be configured to form multiple slip joints JT therebetween (particularly, if the offshore structure 2 has multiple slip joints, the transport device 1 can have multiple slip joints 8 for receiving the offshore structure 2 and forming multiple slip joints JT with the slip joint portion 9 of the offshore structure 2). Providing multiple slip joints for transporting a single structure can be implemented, for example, when transporting a multi-component offshore structure such as a jacket, tripod, or topside, as will be understood by those skilled in the art.

[0073] As can be seen in Figure 5, the slip joints 8, 9 have parallel, preferably coincident, longitudinal axes XX, which preferably extend substantially vertically, at least in the rest position of the offshore structure on a foundation or transport device. The slip joints 8, 9 have inclined surfaces 8A, 9A, which are shown here as frustoconical by way of example only. The inclined surfaces 8A, 9A are inclined relative to a line or axis XX, which here extends substantially vertically and / or substantially parallel to the forces FS and FL. The inclined surfaces 8A, 9A are shaped and inclined such that the weight of the offshore structure pushes the inclined surfaces 8A, 9A outwards and into contact with each other.

[0074] The system is configured to transition from a fixed state to a releasable state, and in the releasable state, the slip joint force of the slip joint JT formed between the transportation device 1 and the marine structure 2 is smaller than the slip joint force in the fixed state.

[0075] The slip joint JT can provide a safe and efficient means for substantially quickly fastening the offshore structure 2 to the transportation device 1. For example, the slip joint JT can be formed and / or maintained under the influence of the weight of the offshore structure 2. Furthermore, in this manner, offshore structures of various sizes can be interchangeably received on the transportation device 1 without substantially requiring specific modifications to the transportation device 1. See FIG. 3b for examples corresponding to offshore structures 302, 302′, 302″ of various sizes. By being configured to transition to a releasable state, the system can provide a safe and efficient means for substantially quickly releasing the offshore structure 2 from the transportation device 1.

[0076] According to one embodiment, in the fixed state, the offshore structure 2 is fixed to the transport device 1, and in the releasable state, the offshore structure 2 is releasable from the transport device 1, for example, using a lifting means (e.g., the lifting means 10 shown in Figure 2c).

[0077] In this way, by transitioning the system from a fixed state to a releasable state, the marine structure 2 can be transitioned from a state in which it is fixed to the transportation device 1 (e.g., for stable and reliable transportation) to a releasable state (e.g., for installing the marine structure 2 at the destination).

[0078] In one embodiment, and with further reference to FIG. 1a, the system further comprises a vibration generator 3 for vibrating the transportation device 1 and the offshore structure 2 relative to each other, in particular for reducing slip joint forces.

[0079] It has been found that such vibration generators 3 can be an effective means for reducing slip joint forces. In Figure 1a, the vibration generators, including, for example, one or more vibration motors, are attached to the transport device 1. In other embodiments, the vibration generators 103 may be attached to the offshore structure 102, as shown, for example, in Figure 1b. It will be understood that combinations and variations of these options are also possible.

[0080] The vibrations are preferably generated substantially at one or more predetermined resonant frequencies.

[0081] Vibration at such frequencies has been found to be particularly effective in reducing slip joint forces.

[0082] In one embodiment, the system further or alternatively includes a separation system 4 including, for example, one or more mechanical force generating devices (e.g., one or more hydraulic jacks) 5 configured to apply a separation force FS between the offshore structure 2 and the transportation device 1. For example, such mechanical force generating devices 5 may include mutually displaceable elements (e.g., hydraulically and / or electrically powered) for generating the separation force FS between the structure 2 and the transportation device 1. As can be seen from the drawings, the separation force FS is preferably directed parallel to the direction of gravity (i.e., intended to counteract gravity). The one or more mechanical force generating devices 5 may be configured, for example, to provide a total maximum force significantly less (e.g., at least 10 times less) than the weight of the offshore structure 2 to be separated. Furthermore, the separation system 4 is separate from an external lifting means 10 (the lifting means 10 may provide a lifting force greater than the weight of the offshore structure 2) that can be used to lift the offshore structure 2 when the releasable state is achieved.

[0083] Such a decoupling system 4 can advantageously provide a means to assist in reducing slip joint forces, and to assist in separating the offshore structure 2 from the transport device 1 while the slip joint forces are being reduced, e.g., complementary to the vibration generator 3. Decoupling the offshore structure 2 from the transport device 1 in this way helps to prevent slip joint forces from increasing again after they have been reduced, e.g., under the influence of the offshore structure's own weight and / or in response to manipulation of the offshore structure 2, e.g., by external lifting means 10 (see Figure 2c).

[0084] Figures 1a and 1b show different options for the separation system 4. Figure 1a shows a mechanical force generating device 5 attached to the interior surface of the offshore structure 2 and configured to push substantially downwards on the top of the transportation device 1, and Figure 1b shows a mechanical force generating device 5 attached to the transportation device 1 and configured to push substantially upwards on the bottom of the offshore structure 2. It will be understood that combinations and variations of these options are possible. Both the vibration generator 103 and the separation system 104 shown in Figure 1b are different from those shown in Figure 1a, but it will also be understood that these variations are not necessarily dependent on each other.

[0085] Referring to FIG. 3a, in one embodiment the system, preferably the transportation device 201, comprises in addition to the slip joint JT a clamping device 206 for clamping the offshore structure 202 and the transportation device 201 together.

[0086] Here, in the fixed state, compared to the releasable state, the offshore structure 202 and the transportation device 201 are substantially clamped to each other by the clamping device 206 .

[0087] The clamping device 206 may provide a complementary means for fastening and releasing the offshore structure 202 efficiently and quickly.

[0088] The clamping device 206 is preferably configured to push, e.g., hydraulically, one or more, e.g., two, clamping elements 207 in one or more respective clamping directions C extending towards the transport device 201 and / or the offshore structure 202.

[0089] As shown in Figures 2c and 5, in one embodiment, the transportation device 1 and the offshore structure 2 each include respective slip joint portions 8, 9 which are inclined surfaces, preferably joining surfaces, such as conical or frustoconical surfaces, and the respective slip joint portions 8, 9 are configured to form a slip joint JT with each other, particularly when they are arranged so as to abut each other, for example facing the receiving direction R (see Figure 5).

[0090] Such slip joints 8, 9 can provide an effective means for forming the slip joint JT. Furthermore, they can provide a means for interchangeably receiving offshore structures of various sizes on a transportation device without substantially requiring specific modifications to the transportation device. For example, as shown in FIG. 3b, slip joints having various sizes of frustoconical surfaces of offshore structures 302, 302', 302" can be received by lowering them onto corresponding slip joints at various heights on the frustoconical surface of the transportation device.

[0091] It will be appreciated that the offshore structure 2 may only be partially shown in the schematic diagram of FIG.

[0092] In one embodiment, as shown in Figures 2c and 5, the slip joint portion 8 of the transportation device 1 is configured to receive the offshore structure 2 in a receiving direction R, and in particular is configured to form a slip joint JT (see, for example, Figure 2a) together with the slip joint portion 9 of the offshore structure 2.

[0093] Here, the receiving direction R substantially coincides with the direction of gravity acting on the marine structure 2, and in particular, the receiving direction R is substantially downward.

[0094] Advantageously, the slip joint JT can thus be formed and / or maintained under the influence of the offshore structure 2's own weight.

[0095] As shown in Figures 2a to 2c, in one embodiment the system further comprises a lifting device 10, such as a crane, which is configured to lift the offshore structure 2 and preferably position it relative to, in particular, the transport device 1 and / or another structure, such as a loading base structure 11 (see Figure 4a) and / or a destination base structure 12 (see Figure 4b).

[0096] Such a lifting device 10 can provide a means for releasing the offshore structure 2 from the transport device 1, particularly when the system is in a releasable state. Using the same or a similar lifting device 10, it is possible to form the slip joint JT, for example, by lowering the offshore structure 2 onto the transport device 1 (e.g., in a receiving direction R, see Figure 2c).

[0097] Figure 2a shows the lifting device 10 in a substantially unloaded state while the slip joint JT is being formed. When the system enters the releasable state, as shown in Figure 2b, the lifting device 10 is brought into a loaded state, after which the lifting device 10 lifts the offshore structure 2 (see Figure 2c) and releases the offshore structure 2 from the transport device 1. Figures 2b and 2c show the direction FL of the lifting device force of the lifting device 10.

[0098] In one embodiment, the system is configured to transport the marine structure 2 from a loading site, and the system further comprises a loading site base structure 11 (see Figure 4a), for example a foundation, at the loading site, the loading site base structure 11 being configured, for example, to form a slip joint JL together with the marine structure 2.

[0099] This system is configured to transition from a loading base fixed state to a loading base releasable state, and is configured so that in the loading base releasable state, the slip joint force of the slip joint JL formed between the loading base structure 11 and the marine structure 2 is smaller than the slip joint force in the loading base fixed state.

[0100] In this way, the marine structure 2 can be loaded safely, efficiently, and quickly at the loading site. For example, the slip joint JL with the loading site base structure 11 can be formed and released in this way, similar to the slip joint JT with the transportation device 1.

[0101] In one embodiment, and with further reference to FIG. 4a, the system comprises a vibration generator 3 for vibrating the load-carrying base structure 11 and the offshore structure 2 relative to one another, in particular for reducing slip joint forces in the slip joint JL formed by these structures, wherein the vibrations are preferably generated substantially at one or more predetermined resonant frequencies.

[0102] Such vibration generators may provide similar advantages (albeit with some differences) as compared to the previously described vibration generators for vibrating the transportation device and the offshore structure relative to one another. In some embodiments, the vibration generators may be substantially the same as those previously described, for example, when the vibration generators 3 are substantially included in the offshore structure 2. Alternatively, for example, as shown in FIG. 4a, the vibration generators may be load-based vibration generators 410 attached to the load-based structure 411.

[0103] In one embodiment, and with further reference to FIG. 4 a , the system comprises a load-based separation system 13 , including, for example, one or more mechanical force generating devices 5 , configured to apply a separation force FS between the offshore structure 2 and the load-based structure 11 .

[0104] Such load-based separation systems may provide similar advantages (albeit with some differences) as compared to the previously described separation systems for applying a separation force between an offshore structure and a transportation device. In some embodiments, the load-based separation system 13 may be substantially the same as or included in the previously described separation system 4, for example, if the separation system 4 is substantially included in the offshore structure.

[0105] In one embodiment, referring to FIG. 4b, the system is configured to transport the offshore structure 2 to a destination, and the system further comprises a destination base structure 12, such as a foundation, at the destination, the destination base structure 12 being configured to receive the offshore structure 2 and form a slip joint JD together with the slip joint portion 9 of the offshore structure 2.

[0106] In this way, the marine structure 2 can be installed safely, efficiently, and quickly at the destination. For example, compared to the slip joint JT with the transportation device 1, in this way, the slip joint JD with the destination base structure 12 can be formed in the same way.

[0107] In one embodiment, as shown in FIG. 3b, the transportation device 1 is configured to receive a plurality of offshore structures 302, 302′, 302″ and form respective slip joints JT, JT′, JT″ with the slip joint portions 9 of each of the received offshore structures 302, 302′, 302″.

[0108] The system is configured to transition from a respective fixed state to a respective releasable state for each received marine structure 2, and in the releasable state, the slip joint force of the slip joint JT formed between the transportation device 1 and the marine structure 2 is smaller than the slip joint force in the fixed state.

[0109] Such a system is advantageous in that multiple offshore structures can be transported simultaneously while enjoying the benefits described above. It will be understood that the system may be configured to receive more or fewer offshore structures than shown in Figure 3b, and that the relative positions of the received offshore structures relative to each other and to the transport device may differ from the configuration shown in Figure 3b. For example, the offshore structures may be positioned according to a matrix configuration. It will also be understood that the multiple offshore structures may or may not each be the same type and / or size.

[0110] In one embodiment, the offshore structure 2 includes one or more wind power generating devices 2 and / or one or more wind power generating components, such as piles 14 and / or nacelles 15 (see FIG. 4b). In other examples, the offshore structure 2 may include a jacket or a topside.

[0111] In one embodiment, the offshore structure 2 has a mass greater than 50,000 kg or greater than 490,000 N.

[0112] Such a large mass is advantageous in that it helps form a slip joint under the influence of the offshore structure's own weight.

[0113] The method for transporting an offshore structure includes the steps of receiving an offshore structure 2 on a transport device 1 and forming a slip joint JT between the transport device 1 and the received offshore structure 2, reducing the slip joint force of the slip joint JT, and releasing the offshore structure 2 from the transport device 1 after the slip joint force has been reduced (see, for example, Figure 2c).

[0114] In one embodiment, the method further includes generating vibrations of the offshore structure 2 and / or the transportation device 1, preferably substantially at one or more predetermined resonant frequencies, thereby reducing the slip joint force of the slip joint JT.

[0115] In one embodiment, the method further comprises applying a separation force FS between the offshore structure 2 and the transportation device 1 .

[0116] In one embodiment, the separation force FS is applied before generating the vibration.

[0117] This has been found to be effective in reducing slip joint forces due to vibration.

[0118] In one embodiment, the separation force FS is applied while generating the vibration.

[0119] In this way, the marine structure 2 can be separated from the transportation device 1 in a particularly stable and well-controlled manner.

[0120] In one embodiment, the method further includes a step of measuring the displacement of the marine structure 2 relative to the transportation device 1 and / or a step of measuring the pressure between the marine structure 2 and the transportation device 1, and a step of releasing the marine structure 2 from the transportation device 1 in response to the measured displacement and / or pressure.

[0121] In this way, the marine structure 2 can be released smoothly, safely, and efficiently from the transportation device 1. For example, the marine structure 2 may be released after it is measured that the displacement is greater than a predetermined threshold displacement and / or after it is measured that the pressure is less than a predetermined threshold pressure.

[0122] To measure displacement and / or pressure, the isolation system 4 may include one or more measuring devices (not shown), such as a displacement measuring device (e.g., using a camera) and / or a pressure measuring device (e.g., for measuring the pressure of the hydraulic working fluid of the mechanical force generating device or jack 5).

[0123] In one embodiment, the method further comprises using active heave compensation, particularly during release.

[0124] It has been found that the transportation, and in particular the release, of offshore structures can be made more stable and / or better controlled through the use of active heave compensation.

[0125] To this end, for example, the lifting device 10 may include a system for active heave compensation. Related general systems and methods for active heave compensation will be known to those skilled in the art.

[0126] The above-described embodiment may include a transportation device 1, in particular a ship or vehicle, configured to receive an offshore structure 2 and form a slip joint JT together with a slip joint portion 9 of the received offshore structure 2.

[0127] In an embodiment, the transport device comprises a vibration generating device 3 for vibrating the transport device 1 and the offshore structure 2 carried on the transport device 1 relative to each other, in particular for reducing the slip joint forces of the slip joint JT.

[0128] In an embodiment, the transportation device comprises a separation system 4 including, for example, one or more jacks and / or other force generating devices 5 configured to apply a separation force FS between the offshore structure 2 and the transportation device 1 .

[0129] The above-described embodiments may include an offshore structure 2, in particular including a wind power generation device 2 and / or one or more wind power generation components 14, 15, the offshore structure 2 being provided with a slip joint part 9 configured to form a slip joint JT together with a transport device 1, for example the slip joint part 8 of the transport device described above, in order to secure the offshore structure 2 to the transport device 1.

[0130] In an embodiment, the offshore structure is provided with a vibration generating device 3 for vibrating the transport device 1 carrying the offshore structure 2 and the offshore structure 2 relative to each other, in particular for reducing the slip joint force of the slip joint JT.

[0131] In an embodiment, the offshore structure is provided with a separation system 4 including, for example, one or more mechanical force generating devices 5 configured to apply a separation force FS between the transportation device 1 and the offshore structure 2 .

[0132] The disclosed embodiments are presented by way of example only and should not be construed as limiting the scope of the present disclosure. Many variations are possible within the scope of the present invention as defined by the claims.

[0133] For example, the system may be configured to form multiple slip joints per offshore structure, e.g., two, three, or four slip joints per offshore structure, and multiple slip joints may be simultaneously formed, simultaneously releasable, and / or simultaneously released. In this manner, for example, a jacket or topside having three or four legs may be transported with the described advantages.

[0134] The vibration generators can be configured to generate vibrations of various durations and magnitudes to reduce the respective slip joint forces, depending, for example, on the particular configuration of the respective slip joint.

[0135] The vibration device may be configured to generate the mutual acceleration by applying at least one impact to the slip joint, for example to the offshore structure, using, for example, an impact device or a hammer device.

[0136] The transport device may include a propulsion system and / or may be configured to be propelled by an external propulsion force.

[0137] The transport device may be, for example, a barge. The received offshore structure may additionally be fastened to the transport device using known fastening methods, for example using one or more nuts and bolts.

[0138] The offshore structure and / or the transport device may include one or more, preferably each, guide means for guiding the offshore structure relative to the transport device during receiving and / or releasing of the offshore structure, for example to align the offshore structure with the transport device.

[0139] The slip joint 8 of the transport device 1 can be configured in various ways. The slip joint 8 of the transport device 1 can be an inseparable part of the transport device 1, for example made integral with the transport device 1, but this is not required.

[0140] The slip joint 8 of the transportation device 1 may be, for example, a joint that is welded and / or bolted to a support frame, deck, and / or other portion of the transportation device 1. The slip joint 8 of the transportation device 1 may be, for example, but is not required to be, made of steel. The slip joint 8 of the transportation device 1 may be a portion that can be removed from the transportation device 1 after use (i.e., after being used to provide a slip joint with the offshore structure 2 being transported), for example, to make the transportation device 1 available for another type of transportation.

[0141] These and other modifications, including but not limited to the disclosed embodiments or subcombinations thereof, are also considered to be disclosed within the scope of the following claims. [Explanation of symbols]

[0142] 1. Transportation equipment 2.Ocean structures 3. Vibration generator 4. Separation system 5. Mechanical force generator 6. Clamping device 7. Clamping elements 8. Slip joints in transport equipment 9. Slip joints in marine structures 10. Lifting equipment 11. Loading base structure 12. Destination base structure 13. Load base separation system 14. Pile 15. Nasser 16. Loading base vibration generator C. Clamping direction FS.Separation force FL. Lifting device force JD. Slip joint formed by destination base structure and offshore structure JL. Slip joint formed between the loading base structure and the offshore structure JT. Slip joint formed between transportation equipment and marine structure R. Receiving direction

Claims

1. 1. A system for transporting an offshore structure, comprising: A transport device (1), in particular a ship or vehicle, configured to receive an offshore structure (2) and form a slip joint (JT) with a slip joint portion (9) of the received offshore structure (2), the slip joint (JT) is formed between a lower end of the offshore structure (2) forming the slip joint portion (9) of the offshore structure (2) and a complementary slip joint portion (8) of the transportation device (1) to provide slip joint retention; the slip joint portion (8) of the transportation device (1) comprises a conical or frusto-conical surface (8A), and the slip joint portion (9) of the offshore structure (2) comprises a complementary conical or frusto-conical surface (9A); the slip joint (JT) is formed and / or maintained under the influence of the weight of the offshore structure, and in use the conical or frusto-conical surfaces (8A, 9A) of the slip joint portions (8, 9) come together and are arranged so that the weight of the offshore structure (2) further presses the offshore structure (2) against the slip joint portion (8) of the transportation device (1), thereby providing the slip joint holding force; The system is configured to transition from a fixed state to a releasable state, and in the releasable state, the slip joint holding force of the slip joint (JT) formed between the transportation device (1) and the offshore structure (2) is smaller than the slip joint holding force in the fixed state.

2. 2. The system of claim 1, further comprising an offshore foundation including a slip joint portion having a conical or frustoconical surface complementary to the slip joint portion (9) of the offshore structure (2).

3. 3. The system of claim 1 or 2, wherein the slip joint comprises an upper end of the slip joint portion (8) of the transport device.

4. 4. The system according to claim 1, wherein in the fixed state, the offshore structure (2) is fixed to the transport device (1), and in the releasable state, the offshore structure (2) is releasable from the transport device (1) using a lifting means.

5. a vibration generating device (3) for vibrating the transportation device (1) and the marine structure (2) relative to each other to reduce the slip joint holding force; The system of claim 1 , further comprising:

6. 6. The system according to claim 5, wherein the vibrations of the vibration generator (3) occur substantially at one or more predetermined resonant frequencies.

7. a separation system (4) configured to apply a separation force (FS) between the offshore structure (2) and the transport device (1); The system of claim 1 , further comprising:

8. The separation system (4) comprises one or more mechanical force generating devices (5), The system of claim 7.

9. The system comprises, in addition to the slip joint (JT), a clamping device (6) for clamping the marine structure (2) and the transportation device (1) together; In the fixed state, the marine structure (2) and the transportation device (1) are substantially clamped to each other by the clamping device (6), compared to the releasable state.

9. A system according to any one of claims 1 to 8.

10. the clamping device (6) is configured to press one or more clamping elements (7) in one or more respective clamping directions (C) extending towards the transport device (1) and / or the offshore structure (2); The system of claim 9.

11. the transport device (1) is configured to receive the marine structure (2) in a receiving direction R, and in particular to form the slip joint (JT) together with the slip joint portion (9) of the marine structure (2); The receiving direction (R) substantially coincides with the direction of gravity acting on the marine structure (2), and the receiving direction (R) is, in particular, substantially downward.

11. A system according to any one of claims 1 to 10.

12. a lifting device (10) configured to lift the marine structure (2); The system of claim 1 , further comprising:

13. the system is configured to transport the marine structure (2) from a loading location; The system further comprises a load site base structure (11) at the load site; The system is configured to transition from a load base fixed state to a load base releasable state, and in the load base releasable state, the slip joint holding force of a slip joint (JL) formed between the load base base structure (11) and the marine structure (2) is smaller than the slip joint holding force in the load base fixed state.

13. A system according to any one of claims 1 to 12.

14. 14. The system according to claim 13, comprising a vibration generator (3) for vibrating the load base structure (11) and the offshore structure (2) relative to each other, in particular for reducing the slip joint holding force of the slip joint (JL) formed by these structures.

15. 15. The system according to claim 14, wherein the vibrations of the vibration generator (3) occur substantially at one or more predetermined resonant frequencies.

16. 16. The system of any of claims 13 to 15, further comprising a load-based separation system (13) configured to apply a separation force (FS) between the offshore structure (2) and the load base structure (11).

17. 17. The system of claim 16, wherein the load-based separation system (13) includes one or more mechanical force generating devices (5).

18. the system is configured to transport the marine structure (2) to a destination; The system further comprises a destination base structure (12) at the destination; The destination base structure (12) is configured to receive the offshore structure (2) and form a slip joint (JD) with the slip joint portion (9) of the offshore structure (2).

18. A system according to any preceding claim.

19. the transportation device (1) is configured to receive a plurality of marine structures (2) and form respective slip joints (JT) with the slip joint portions (9) of the received marine structures (2); the system is configured to transition, for each received offshore structure (2), from a respective fixed state to a respective releasable state, in which the slip joint holding force of a slip joint (JT) formed between the transportation device (1) and the offshore structure (2) is smaller than the slip joint holding force in the fixed state; 19. A system according to any preceding claim.

20. The offshore structure (2) includes one or more wind power generation devices (2) and / or one or more wind power generation components.

20. A system according to any preceding claim.

21. The transportation device (1) is configured to receive an offshore structure (2) and form a plurality of slip joints (JT) together with slip joint portions (9) of the received offshore structure (2); the system is configured to transition from a fixed state to a releasable state, and in the releasable state, the slip joint holding forces of the slip joints (JT) formed between the transportation device (1) and the offshore structure (2) are smaller than the respective slip joint holding forces in the fixed state; 21. A system according to any one of claims 1 to 20.

22. 1. A method for transporting an offshore structure, comprising: receiving an offshore structure (2) on a transportation device (1) and forming a slip joint (JT) between the transportation device (1) and the received offshore structure (2), the slip joint (JT) being formed and / or maintained under the influence of the weight of the offshore structure (2) to provide a slip joint holding force; the slip joint is formed by lowering the lower end of the marine structure (2) having a conical or frusto-conical surface (9A) onto a slip joint portion (8) of the transportation device (1) having a complementary conical or frusto-conical surface (8A); Reducing the slip joint retention force of the slip joint (JT); releasing the marine structure (2) from the transportation device (1) after reducing the slip joint holding force; A method for providing

23. 23. The method of claim 22, further comprising reducing the slip joint holding force of the slip joint (JT) by generating vibrations of the offshore structure (2) and / or the transportation device (1).

24. 24. The method of claim 23, wherein the vibrations of the offshore structure (2) and / or the transport device (1) are generated substantially at one or more predetermined resonant frequencies.

25. 25. The method according to any one of claims 22 to 24, further comprising applying a separation force (FS) between the offshore structure (2) and the transportation device (1).

26. applying a separation force (FS) between the marine structure (2) and the transportation device (1); 25. The method of claim 23 or 24, wherein the separation force (FS) is applied before generating the vibration.

27. applying a separation force (FS) between the marine structure (2) and the transportation device (1); 25. The method of claim 23 or 24, wherein the separation force (FS) is applied during the generation of the vibrations.

28. measuring the displacement of the offshore structure (2) relative to the transportation device (1) and / or measuring the pressure between the offshore structure (2) and the transportation device (1); Releasing the marine structure (2) from the transportation device (1) in response to the measured displacement and / or pressure.

28. The method of any of claims 22 to 27, further comprising:

29. 29. A method according to any of claims 22 to 28, further comprising using active heave compensation at least during said disengagement.

30. 22. A transport device (1), in particular a ship or vehicle, of a system according to any one of claims 1 to 21, configured to receive an offshore structure (2) and form a slip joint (JT) together with a slip joint portion (9) of the received offshore structure (2), the transport device comprising at least one slip joint portion for forming a slip joint with a lower end of the offshore structure under the effect of the offshore structure's own weight, the slip joint being formed and / or maintained during transport under the influence of the weight of the offshore structure, the slip joint portion (9) of the transport device (1) and the slip joint portion (8) of the offshore structure (2) comprising complementary conical or frusto-conical surfaces (8A, 9A).

31. 31. The transport device according to claim 30, comprising a vibration generator (3) for vibrating the transport device (1) and the offshore structure (2) carried on the transport device (1) relative to each other, in particular for reducing the slip joint holding force of the slip joint (JT).

32. 32. A transport device according to claim 30 or 31, comprising a separation system (4) configured to apply a separation force (FS) between the offshore structure (2) and the transport device (1).

33. 33. The transport device of claim 32, wherein the separation system (4) comprises one or more mechanical force generating devices (5).

34. 22. An offshore structure of a system according to any one of claims 1 to 21, comprising a wind power installation (2) and / or one or more wind power components (14, 15) and / or one or more multi-component offshore structures, the marine structure (2) has at least one slip joint (9) configured to form a slip joint (JT) with each slip joint (8) of the transportation device (1) to secure the marine structure (2) to the transportation device (1); The marine structure includes a vibration generating device (3) for reducing the slip joint holding force of the slip joint (JT) so as to vibrate the transportation device (1) receiving the marine structure (2) and the marine structure (2) relative to each other.

35. The transport device (1) is a transport device according to any one of claims 30 to 33.

35. The marine structure according to claim 34.

36. 36. The offshore structure of claim 34 or 35, comprising a separation system (4) configured to apply a separation force (FS) between the transportation device (1) and the offshore structure (2).

37. The separation system (4) comprises one or more mechanical force generating devices (5), 37. The marine structure according to claim 36.

38. 38. An offshore structure as claimed in any one of claims 34 to 37, wherein the slip joint is formed and / or maintained under the influence of the weight of the offshore structure.

39. 38. The system of any one of claims 1 to 21, the method of any one of claims 22 to 29, the transport device of any one of claims 30 to 33, or the offshore structure of any one of claims 34 or 38, wherein the slip joint is formed during transport between a slip joint portion at a lower end of the offshore structure and an upper end of a slip joint portion of the transport device, and is formed between a slip joint portion at a lower end of the offshore structure and a slip joint portion at an upper end of an offshore foundation during use of the offshore structure.

40. The method described in claim 26, wherein the separation force (FS) is applied while generating the vibration.

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