Parallel mooring lines to the same anchor

Abstract

The present invention relates to a mooring arrangement for mooring a floating unit to the seabed. The mooring arrangement comprises a plurality of mooring clusters, each connectable to a floating unit, and anchors adapted to the seabed. At least one mooring cluster has at least two mooring lines.

Description

Technical Field

[0001]

[0001] The present invention relates to ocean mooring arrangements, systems, and methods. More specifically, it relates to a mooring arrangement in which parallel or substantially parallel mooring lines can be connected to the same floating unit at one end and to the same anchor on the seabed at the other end.

Background Art

[0002]

[0002] Renewable energy is gaining increasing interest in the industry. The main focus of current offshore environmental power generation is wind power generation, and wind turbines are placed either on bottom-fixed structures or moored floating units. To obtain sufficient power generation capacity, some of these structures / units are installed in the same area and connected to each other to form a power plant / wind park.

[0003]

[0003] The costs of these offshore power plants, especially those with moored floating units, are generally higher than those of onshore power plants. In order for offshore wind power plants with moored floating units to be competitive, technology must be optimized. This includes cost reduction in all aspects, including the cost of the product, transportation costs, and the cost for offshore installation.

[0004]

[0004] Moored floating devices typically have three or more mooring lines, and each mooring line is connected to a floating unit at one end and to an anchor at the other end. The floating units within a power plant typically do not share mooring lines and / or anchors, which means that a power plant with N floating units has N·M mooring lines and N·M anchors, where M is the number of mooring lines per floating unit. However, the floating units within a power plant can be arranged in a manner where the anchors are shared among the floating units. Such conventional arrangements are shown in FIGS. 3 to 5. As can be seen from the drawings, the total number of anchors is significantly reduced compared to an arrangement where only individual anchors are used. When the number of anchors is reduced, the hardware cost, transportation cost, and the cost for offshore installation are reduced.

[0005]

[0005] As the size of floating wind turbines increases, mooring rope components such as chains, steel wire ropes, and synthetic fiber ropes approach or exceed the manufacturing limits at supplier facilities. To solve this, it is necessary to increase the number of mooring ropes connected to each floater. However, this has the disadvantage of also increasing the number of anchors, which significantly impacts the overall cost of the mooring system.

[0006]

[0006] Examples of prior art relating to shared anchors or shared mooring ropes are disclosed in Patent Documents US3082608A, NO325261B1, CA2637358A1, CA2725808A1, US8657534B2, JP2011245879A, CN102715107A, US9567040B2, CN111071400A, WO2021078748A1, WO2022013145A1, and WO2022098288A1.

[0007]

[0007] These prior arts mainly relate to shared anchors or shared mooring lines between adjacent floating units (also called "floaters"), and do not refer to shared anchors between mooring lines from the same floater. Patent documents US3082608A and NO325261B1 include mooring line bridle arrangements toward floating units, which are connected to each other at a certain distance from the floater and then further connected to at least one anchor. However, since the purpose of the bridles is to limit the yaw motion of the floating unit and not to reduce the individual mooring line load, the separation angle between the two bridle arms is considerably larger than in the present invention. In US9567040B2, the mooring line is perfectly vertical, unlike in the present invention, in order to reduce the vertical, pitch, and roll motion of the floater. US8657534B2 and JP2011245879A have mooring lines that are slightly inclined with respect to the vertical axis in order to limit the surge, sway, and (particularly) yaw motion of the floater. These ropes are further combined with separate vertical movement limiting devices and are therefore different from the present invention. Furthermore, references US3082608A, US8657534B2, JP2011245879A, and NO325261B1 disclose that multiple mooring rope bridles are connected to a shared connection point on a floating unit.

[0008]

[0008] Unlike US3082608A, US8657534B2, JP2011245879A, and US9567040B2, the present invention has little or no effect on the vertical, pitch, and roll motion of the floater because the horizontal distance between the upper and lower ends of the mooring rope is equal to or greater than the vertical distance between the ends of the rope, i.e., angle B in Figure 14 is less than 45 degrees.

[0009]

[0009] An object of the present invention is to overcome the shortcomings of known prior art and to provide a mooring arrangement in which several mooring lines from the same floater are arranged in parallel or substantially parallel and connected to the same anchor on the seabed.

[0010]

[0010] To achieve these objectives, a system and method described in an independent claim are provided. [Overview of the Initiative]

[0011]

[0011] The present invention is described and characterized in the main claims, and the dependent claims represent other features of the present invention.

[0012]

[0012] In a first aspect of the present invention, the present invention relates to a mooring arrangement for mooring a floating unit to the seabed, the mooring arrangement comprising a plurality of mooring clusters, each connectable to a floating unit, and an anchor adapted to the seabed, wherein at least one mooring cluster comprises at least two mooring lines, and at least two mooring lines of the same mooring cluster are adapted to connect to the same anchor.

[0013]

[0013] In one embodiment of a first aspect of the present invention, the present invention relates to at least two mooring ropes, each comprising a floating unit connection point adapted to be connected to a floating unit, the floating unit connection points being arranged horizontally at intervals of less than 30 meters.

[0014]

[0014] In another embodiment of the first aspect of the present invention, the present invention relates to mooring cables within the same mooring cluster that are separate cables separated along their longitudinal direction, comprising separate anchor connection points at the anchor end and separate floating unit connection points at the floating unit end.

[0015]

[0015] In yet another embodiment of the first aspect of the present invention, the present invention relates to mooring lines within the same mooring cluster that are connected to one another by connecting elements located between anchors and floating units.

[0016]

[0016] In yet another embodiment of the first aspect of the present invention, the present invention relates to a single mooring cable between an anchor connection point and a connecting element, wherein the length of the single mooring cable and the connecting element is less than 50% of the distance between the anchor connection point and the floating unit connection point on the floating unit.

[0017]

[0017] In yet another embodiment of the first aspect of the present invention, the present invention relates to at least two mooring clusters, each mooring cluster comprising two mooring ropes connectable to a common anchor, the first mooring cluster comprising a first set of floating unit connection points connectable to a floating unit, and the second mooring cluster comprising a second set of floating unit connection points connectable to a floating unit, wherein the locations of the first set of floating unit connection points are different from those of the second set of floating unit connection points on the floating unit.

[0018]

[0018] In yet another embodiment of the first aspect of the present invention, the present invention relates to at least two mooring ropes, each comprising a floating unit connection point adapted to be connected to a floating unit, the two floating unit connection points being spaced apart by a first distance D1, the horizontal distance between the anchor connection point of any of the at least two mooring ropes associated with the anchor and either floating unit connection point defines a second distance D2, and the ratio D2 / D1, obtained by dividing the second distance by the first distance, is greater than 5.

[0019]

[0019] In yet another embodiment of the first aspect of the present invention, the present invention relates to an arrangement having a separation angle A of less than 5 degrees, where A is defined as the angle between a first rope 14 and a second rope 15 that reflects a straight line in the horizontal plane between the anchor connection point and the floating unit connection point for the two outermost mooring ropes of the mooring cluster.

[0020]

[0020] In yet another embodiment of the first aspect of the present invention, the present invention relates to an arrangement having an angle B of less than 45 degrees, where the angle B is defined by the angle between the horizontal axis and the straight line between the lower and upper ends of the mooring rope.

[0021]

[0021] In another aspect of the present invention, the present invention relates to a mooring system for mooring a floating unit to the seabed, the mooring system comprising at least one mooring arrangement according to the first aspect, as well as at least one floating unit and at least one anchor.

[0022]

[0022] In one embodiment of a second aspect of the present invention, the present invention relates to at least two mooring clusters, each mooring cluster comprising two mooring ropes connected to a common anchor, the first mooring cluster comprising a first set of floating unit connection points connected to a floating unit, and the second mooring cluster comprising a second set of floating unit connection points connected to a floating unit, wherein the locations of the first set of floating unit connection points are different from those of the second set of floating unit connection points on the floating unit, so that the connection points do not coincide.

[0023]

[0023] In another embodiment of a second aspect of the present invention, the present invention relates to a floating unit comprising at least two structurally connected floating elements, wherein each mooring cluster is associated with each floating element of the floating unit.

[0024]

[0024] In yet another embodiment of a second aspect of the present invention, the present invention relates to a horizontal distance of more than 150 meters between anchor connection points of at least two mooring ropes associated with an anchor and a floating unit connection point associated with a floating unit.

[0025]

[0025] In yet another embodiment of a second aspect of the present invention, the present invention relates to an angle of less than 45 degrees between a vector defined by a straight line between an anchor connection point and a floater connection point and a projection vector representing the projection of the vector onto the seabed.

[0026]

[0026] In yet another embodiment of the second aspect of the present invention, the present invention relates to at least two mooring lines each having a mooring line connection point connected to a floating unit, the two mooring line connection points being separated by a first distance D1, and the horizontal distance between any mooring line connection point of at least two mooring lines connected to an anchor and any mooring line connection point defines a second distance D2, and the ratio D2 / D1 given by dividing the second distance by the first distance is greater than 5.

[0027]

[0027] In yet another embodiment of the second aspect of the present invention, the present invention relates to a mooring cluster having a separation angle A of less than 5 degrees, where A is defined as the angle between a first cable 14 and a second cable 15 that reflects a straight line in the horizontal plane between the anchor connection point and the floating unit connection point for the two outermost mooring lines of the mooring cluster.

[0028]

[0028] In yet another embodiment of the second aspect of the present invention, the present invention relates to an arrangement having an angle B of less than 45 degrees, where angle B is defined by the angle between a horizontal axis and a straight line between the lower and upper ends of the mooring line.

[0029]

[0029] In yet another embodiment of the second aspect of the present invention, the present invention relates to a floating unit that is a floating wind turbine.

[0030]

[0030] In yet another embodiment of the second aspect of the present invention, the present invention relates to a floating unit that is a unit for oil and gas applications or other energy-related applications.

[0031]

[0031] In yet another embodiment of the second aspect of the present invention, the present invention relates to a floating unit that is a semi-submersible, ship-shaped, or barge-shaped unit.

[0032]

[0032] In yet another embodiment of the second aspect of the present invention, the present invention relates to mooring lines within the same mooring cluster that have the same structure and length.

[0033]

[0033] In yet another embodiment of a second aspect of the present invention, the present invention relates to mooring ropes within the same mooring cluster that differ in structure and length.

[0034]

[0034] In yet another embodiment of a second aspect of the present invention, the present invention relates to an anchor that is shared by mooring lines from the same mooring cluster of the same floating unit and also shared by mooring lines from other floating units.

[0035]

[0035] In a third embodiment of the present invention, the present invention relates to mooring lines within the same mooring cluster that are installed in parallel and simultaneously between an anchor and a floating unit.

[0036]

[0036] In a fourth embodiment of the present invention, the present invention relates to the use of the first and / or second embodiments for mooring a floating unit.

[0037]

[0037] Various embodiments of the present invention will be described below with reference to the drawings. [Brief explanation of the drawing]

[0038] [Figure 1] This is a perspective view showing a typical overall configuration of a mooring unit / floater equipped with mooring ropes. [Figure 2] This is a side view showing a typical overall configuration of a mooring unit / floater equipped with mooring ropes. [Figure 3] The image shows a mooring configuration of multiple floaters (24 off), with each floater moored by three mooring lines, and several anchors shared among the floaters. [Figure 4] The diagram shows a mooring configuration of multiple floaters (20 off), with each floater moored by four mooring lines, and several anchors shared between the floaters. [Figure 5] The image shows a mooring configuration of multiple floaters (24 off), with each floater moored by 6 mooring lines, and several anchors shared between floaters. [Figure 6]This shows a typical structure of a mooring leg. [Figure 7] This shows a typical structure of a mooring leg equipped with a buoyancy element. [Figure 8] The mooring layout of the floater is shown with eight mooring lines and four anchors, with the lines connected to the same anchor being nearly parallel. [Figure 9] The mooring layout of the floater is shown with eight mooring lines and four anchors, where the lines connected to the same anchor are parallel. [Figure 10] This is a top view showing the mooring layout of a floater equipped with six mooring lines and three anchors, where lines connected to the same anchor are separated at angle A. [Figure 11] This is a top view showing the mooring layout of a floater equipped with six mooring lines and three anchors, where lines connected to the same anchor are connected to each other at points between the anchor and the floater. [Figure 12] This is a top view showing the mooring layout of a floater equipped with six mooring lines and three anchors. The lower ends of the lines within the mooring cluster are connected to each other at a certain distance from the anchors, forming a common anchor connection point. [Figure 13] This figure is identical to Figure 10, but shows all the ropes and anchors. [Figure 14] This is a side view showing the mooring layout of the floater. [Figure 15] This diagram shows the installation area of ​​a typical floating unit. [Modes for carrying out the invention]

[0039]

[0038] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. The following description will use terms such as “horizontal,” “vertical,” “lateral,” “front and back,” “up and down,” “top,” “bottom,” “inside,” “outside,” “front,” and “rear.” The longitudinal direction is defined as the direction along the central axis. These terms generally refer to the figures and directions shown in the drawings and associated with the ordinary use of the present invention. The terms are used for the convenience of the reader only and are not limiting. The same number on different drawings represents the same feature. A number with an apostrophe represents an additional feature represented by the same number, for example, the number 4 represents one of several or all of the first or several, and the number 4' represents an additional or further of the same feature, such as a second or several of the same feature.

[0040]

[0039] Figures 1 and 2 show an overall diagram of a typical mooring system configuration that is conventionally known for a floating wind turbine. In this diagram, the floating unit 1 on the sea surface 5 is moored to the seabed 6 by mooring lines 4 that are connected to the floating unit 1 at the upper end and to individual anchors 2 at the lower end.

[0041]

[0040] The main purpose of the mooring system is to keep the floating wind turbine 1 within a certain circulating boundary when subjected to environmental loads such as wind, waves, and currents. The circulating boundary is determined by the circulating capacity of the power cable 7. In another example, the power cable can be a fluid cable or a control cable, and the floating unit can be any type of unit moored to the seabed within the mooring cable 4. Other types of floating units can be semi-submersible platforms, SPAR platforms, ship-shaped units, or barges for the oil and gas or energy industry, such as floating production and storage units, floating storage units, floating liquefied natural gas production vessels, floating storage and regasification units, floating nuclear power plants, and floating gas power plants.

[0042]

[0041] Figures 3 to 5 show various examples in which floating units 1 share the same anchor 3, for example, in a wind power plant. The anchor shown in Figure 1 is not individual, but an anchor to which mooring cables 4 from several floating units are connected. At the external boundary of the wind power plant, the anchor 2 is connected to only one floating unit, but at the anchor inside the wind power plant, several floater units are connected to the same anchor 3.

[0043]

[0042] Figure 6 shows a typical arrangement of a mooring leg. The mooring leg comprises individual anchors 2 and mooring ropes 4. In this embodiment, one end of the mooring rope 4 is connected to the anchor connection part 9 and the other end is connected to the floater connection part 10. The mooring rope can be assembled in various combinations, including, for example, chains, steel wire ropes, synthetic fiber ropes, buoys, clamp weights, shackles, H-links, Y-links, mooring connectors, mooring tensioners, etc.

[0044]

[0043] The mooring rope in Figure 6 comprises an H-link leading to the anchor, a lower chain segment, a second H-link, a synthetic fiber rope segment, a third H-link, an upper chain segment, and a mooring connector leading to the floating unit.

[0045]

[0044] Figure 7 shows another typical mooring rope structure, which includes a buoy 11 between the lower part 25 and the upper part 26 of the mooring rope 4.

[0046]

[0045] Figure 8 shows one embodiment of the present invention, comprising eight mooring lines 4, which are configured into four mooring clusters, each cluster having two mooring lines 4a, 4b. Thus, a mooring cluster can be considered as one or more lines leading from a common anchor 3 to substantially identical parts of the floater. It should be understood that the common anchor 3 is the exact same anchor. Substantially identical parts of the floater refer to identical parts such as a single structure such as a pontoon, legs, structure, deck, or floating device, or parts within 30 meters of each other where the structures are not easily distinguishable. The two lines of each cluster are connected to the same anchor 3 and are positioned substantially parallel between the floating unit 1 and the anchor 3. The drawings do not show the perfect parallel relationship between the two mooring lines, but it should be understood that these drawings are not full-dimensional drawings, and as the distance between the anchor 3 and the floating unit 1 increases, the lines branch out toward a parallel relationship, i.e., substantially parallel. The point of maximum separation between the two lines is the connection point toward the floating unit 1.

[0047]

[0046] Figure 9 shows another embodiment of the present invention in which four mooring clusters are configured to moor one floating unit 1, and in each of the four mooring clusters, two mooring ropes 4a and 4b are positioned perfectly parallel to each other between the floating unit 1 and the anchor 3.

[0048]

[0047] Figure 10 shows a mooring arrangement 20 connected to a semi-submersible floating unit 1. The mooring arrangement comprises a plurality of mooring clusters 24, each mooring cluster connectable to the floating unit 1 and anchor 3. The anchor 3 is adapted for installation or burial in the seabed 6. Each mooring cluster comprises at least two mooring ropes 4a, 4b, and the mooring arrangement is adapted so that at least two mooring ropes 4a, 4b of the same mooring cluster are connected to the same anchor 3. The present invention also relates to a mooring system 20, in which a plurality of mooring clusters 24 are connected to their respective anchors and floating units 1, and each mooring cluster is connected to the floating unit 1 and anchor 3. Here, the anchor 3 is buried or fixed in the seabed 6, and each mooring cluster comprises at least two mooring ropes 4a, 4b, and at least two mooring ropes 4a, 4b of the same mooring cluster 24 are connected to the same anchor 3.

[0049]

[0048] In Figures 10 and 13, the present invention is shown in relation to a semi-submersible floater, in which three buoyancy columns 12, 12', and 12'' are illustrated, which are interconnected by braces 13. The mooring system 20 comprises six mooring lines arranged in three mooring clusters 24, each cluster containing two mooring lines 4a, 4b. The two mooring lines in each cluster are connected to the same buoyancy column 12 at connection points 10a and 10b, respectively. At the other end, the two mooring lines are connected to the same anchor at connection points 9a and 9b, respectively. Due to the limitations on the dimensions of the buoyancy columns 12, 12', and 12'', the separation angle A is usually less than 4-5 degrees. The separation angle A refers to the separation angle of two mooring lines 4a, 4b within the same mooring cluster in the horizontal plane, i.e., in the projection plane of the mooring arrangement and / or mooring lines 4a, 4b onto the sea surface (or seabed). In the illustrated example, the floating unit 1 comprises three structurally connected floating elements 12, 12', and 12'', and each mooring cluster is associated with the respective floating elements 12, 12', and 12'' of the floating unit 1.

[0050]

[0049] The horizontal distance between connection points 10a and 10b is preferably 6 to 10 m in order to reduce the possibility of an object falling from near the floating unit damaging both mooring lines (a wider distance is preferable) and to limit the load unevenness between the two lines (a narrower distance is preferable). In the case of a semi-submersible floating unit, the upper limit of the practical horizontal distance between connection points 10a and 10b is preferably 25 to 30 m. When a horizontal distance of 30 m between connection points 10a and 10b is combined with a separation angle A of 5 degrees, the horizontal distance between the anchor connection point 9 and the floating connection point 10 is 340 m. On the other hand, when the separation angle A is 3 degrees and the horizontal distance between connection points 10a and 10b is 10 m, the horizontal distance between the anchor connection point 9 and the floater connection point 10 is 190 m. In yet another example, if the separation angle A is 1.7 degrees and the horizontal distance between connection points 10a and 10b is 30m, the distance between the anchor connection point and the floater connection point will be 1000m. In practice, the horizontal distance between anchor connection point 9 and floater connection point 10 will exceed 150m.

[0051]

[0050] When connecting the second mooring rope of the mooring cluster, it is also beneficial to provide a horizontal separation distance between the connection part 10a and 10b in order to reduce the risk of damaging the first mooring rope that has already been installed.

[0052]

[0051] The dimensions of the anchor 3 are generally smaller than those of the buoyancy column 12. Therefore, the horizontal separation distance between connection points 9a and 9b on the anchor is usually smaller than the distance between 10a and 10b on the floater side, and is about 1 to 3 m. The anchor connection point 9 may be a single point.

[0053]

[0052] To avoid load unevenness, mooring ropes 4 within the same mooring cluster may be identical in length and structure and perfectly parallel. In this case, these ropes are subjected to the same load. However, identical load history can be a disadvantage because a failure in one of these ropes due to an unexpected failure mode may also lead to the failure of adjacent ropes. For example, identical ropes and identical load history also suggest identical fatigue life and simultaneous fatigue failure risk. Therefore, it may be preferable to design parallel or nearly parallel mooring ropes within the same cluster slightly differently so that they have different load histories. If the other ropes can provide sufficient reserve capacity (e.g., fatigue life) after the most important mooring rope fails, it will provide enough time for repair without additional failure. Differences in load history can be obtained by using a separation angle A greater than 0 degrees, differences in rope length, different rope structures that result in different rope stiffness and weight distribution, or a combination thereof.

[0054]

[0053] Figure 11 shows another example in which mooring ropes 4a and 4b within the same mooring cluster are connected to each other at one or more points by a connecting element 19 positioned between the anchor connection point 9 and the floating unit connection point 10. This connecting element 19 can be, for example, the buoy 11 shown in Figure 7. It can also be a clamp weight, a mooring rope tension device, a triplate, or any other structural component. In this configuration, the separation angle A is defined as the angle between the virtual ropes 14 and 15, shown by dotted lines in Figures 11 and 12. These ropes reflect a straight line in the horizontal plane between the anchor connection point 9 and the floating unit connection point 10 for the two outermost mooring ropes in the mooring cluster. In this example, the outermost mooring rope 16 is defined as a lower section 16a between the anchor 3 and the connecting element 19, and an upper section 16b between the connecting element 19 and the floating unit 1. In this embodiment, the outermost mooring rope 17 is defined as the lower section 17a between the anchor 3 and the connecting element 19, and the upper section 17b between the connecting element 19 and the floating unit 1.

[0055]

[0054] As another example, as shown in Figure 11, the ropes 16a and 17a between the anchor 3 and the connecting element 19 can be achieved with a single rope. As shown in Figure 12, the ropes 16a and 17a are combined into a single rope segment 21, one end of which is connected to a single anchor point 9 and the other end to the connecting element 19. To reduce the risk that this single rope 21 will be the weakest point, the rope 21 can be given a strength higher than the combined strength of ropes 16b and 17b. Furthermore, to reduce the risk of external damage to the rope 21, the length of the rope 21 should be shorter than the total length of the mooring rope 4. Preferably, the sum of the length of the rope 21 and the length of the connecting element 19 should be less than 30-50% of the nominal distance between the anchor connection point 9 and the floating unit connection points 10a and 10b. This should be understood as meaning that the separation angle C between ropes 16b and 17b (the angle on the horizontal plane, i.e., the plane on which the arrangement is projected onto the sea surface or seabed) is less than 8 to 10 degrees, since the separation angle A is less than 4 to 5 degrees (see above). In a perfectly horizontal mooring arrangement, i.e., when the mooring rope 4 has an inclination angle of 90 degrees with respect to the vertical axis, the separation angle at the joint surface between ropes 16b and 17b (i.e., the bridle surface defined by ropes 16b and 17b) is also less than 8 to 10 degrees. However, when the mooring arrangement is inclined at 45 degrees with respect to the vertical axis, the separation angle between ropes 16b and 17b (within the bridle surface) is 5.7 to 7.1 degrees, which is significantly lower than the angle range of 20 to 60 degrees described in Patent Document No. 325261B1.

[0056]

[0055] Figure 13 shows an example of a mooring arrangement comprising at least two mooring clusters. In the specific illustration, three mooring clusters 24, 24', 24'' are shown, and each mooring cluster comprises two mooring lines 4a, 4b that can be connected to their respective anchors 3, 3', 3''. In this example, each mooring cluster can be connected to the floating unit 1 and the anchors 3 fitted to the seabed 6. Each mooring cluster can also be connected to different sections 12, 12', 12'' of the mooring unit 1. In another embodiment, the present invention relates to a mooring system comprising at least two mooring clusters 24, 24', 24'', each mooring cluster comprising two mooring lines 4a, 4b connected to their respective anchors 3, 3', 3'', and each mooring cluster is connected to the floating unit 1 and the anchors 3 embedded in the seabed 6. Each mooring cluster may also be connected to different sections 12, 12', 12'' of the mooring unit 1. Although Figure 13 only discloses three mooring clusters 24, 24', and 24'', it should be understood that the present invention can have any number of mooring clusters, such as 1, 2, 3, 4, 5, etc.

[0057]

[0056] Figure 13 further shows a first mooring cluster 24 having a first set of floating unit connection points 10a, 10b that are connectable to or connected to floating unit 1 or different sections 12, 12', 12'' of mooring unit 1, and a second mooring cluster 24' having a second set of floating unit connection points 10a', 10b' that are connectable to or connected to floating unit 1 or different sections 12, 12', 12'' of mooring unit 1. In the shown example, the locations of the first set of floating unit connection points 10a, 10b are different from the locations of the second set of floating unit connection points 10a', 10b' on the floating unit, so the connection points are not shared. In the shown example, all connection points between the mooring rope and floating unit 1 or a part thereof are unique in that they do not coincide.

[0058]

[0057] The present invention may relate to catenary mooring systems, or semi-tensioned or tensioned mooring systems. The mooring arrangement or system shall primarily restrict the floating unit in the horizontal plane, i.e., in surge, sway, and yaw motion. The effect on vertical, pitch, and roll motion is limited. This means that the mooring lines are arranged primarily horizontally, suggesting that the vertical distance between the lower and upper ends of the mooring line 4 is smaller than the horizontal distance between the lower and upper ends of the mooring line 4. That is, angle B in Figure 14 is less than 45 degrees. Angle B is the angle between the horizontal axis, exemplified here by the seabed 6, and a virtual straight line 18 (or vector) connecting the lower and upper ends of the mooring line 4, when the mooring line is viewed from the side. The horizontal axis is a vector on the seabed obtained by projecting vector 18 from three-dimensional space onto the two-dimensional seabed.

[0059]

[0058] Angle A, angle B, angle C, and other dimensions refer to the nominal scenario, i.e., the state in equilibrium where the floating unit (1) is not exposed to any wind, waves, currents, and other external forces.

[0060]

[0059] The present invention relates to a mooring arrangement 20 or mooring system, comprising at least two mooring ropes 4a, 4b each connected to or connectable to a floating unit 1, the two floating unit connection points 10, 10a, 10b being spaced apart by a first distance D1 when connected to the floating unit 1.

[0060] The horizontal distance D2 between any of the anchor connection points 9, 9a, 9b of at least two mooring ropes 4a, 4b associated with anchor 3 and any of the floating unit connection points 10, 10a, 10b defines a second distance D2, and the ratio D2 / D1 obtained by dividing the second distance by the first distance is greater than 5. For example, if the anchor connection points 9, 9a, 9b and the floating unit connection points 10, 10a, 10b are separated by a distance D2 = 150, the maximum separation distance between the two outer floating unit connection points 10a, 10b can be D1 = 30 meters, and D2 / D1 = 150 / 30 = 5.

[0061]

[0061] The present invention relates to a mooring arrangement 20 or system, the arrangement having a separation angle A of less than 5 degrees, where A is defined as the angle between the first rope 14 and the second rope 15, reflecting the straight line in the horizontal plane between the anchor connection points 9, 9a, 9b and the floating unit connection points 10, 10a, 10b to the two outermost mooring ropes of the mooring cluster. The separation angle A may be 5 degrees or less, 4 degrees or less, or 1.7 degrees or less.

[0062]

[0062] The present invention relates to a mooring arrangement 20 or system, the arrangement comprising an angle B of less than 45 degrees, the angle B being defined by the angle between the horizontal axis and a straight line 18 between the lower and upper ends of the mooring ropes 4a, 4b, 4a', 4b'.

[0063]

[0063] The present invention can also be combined with an anchor shared between different floating units 1, as shown in Figures 3 to 5, in which one anchor 3 is sequentially connectable to two or more mooring clusters or connected to two or more floating units. In this example, the present invention relates to a mooring system for mooring two or more floating units 1 to the seabed 6, the mooring system comprising at least two mooring clusters 24, each mooring cluster being connectable to or connected to at least two mooring ropes 4a, 4b, where at least two mooring clusters 24 are connectable to or connected to an anchor 3.

[0064]

[0064] A typical floating unit 1 has an installation area of ​​1000 to 1500 m² at the waterline. 2 This exceeds [a certain value]. In this specification, the installation area is defined as the closed area inside a virtual, tight rope sling surrounding the outermost point of the floating unit 1 at the waterline 5. In Figure 15, the installation area of ​​the semi-submersible floating unit (1) is exemplified as the shaded area 23, which is the area enclosed by the virtual rope sling 22. In this example, the outermost point is the buoyancy column 12. For the semi-submersible unit shown in Figure 15, the brace 14 is not the outermost point.

[0065]

[0065] When using parallel or nearly parallel mooring lines 4 connected to the same anchor 3, it is possible to install the mooring lines 4 simultaneously. After the anchor is installed, all lines connected to the same anchor 3 can be connected to the anchor at connection points 9, 9a, and 9b before the installation vessel lays / pre-lays the mooring lines 4 simultaneously and parallel from the anchor end to the floater end.

[0066]

[0066] While specific embodiments of the present invention have been described and illustrated herein, it will be understood that modifications and variations that are readily conceivable to those skilled in the art exist, and therefore the claims are intended to be interpreted to encompass such modifications and equivalents. For example, the present invention is not limited to having two mooring lines 4 within each mooring cluster, but is limited to having at least two mooring lines between boundary limits defined by angles A and C. [Explanation of symbols]

[0067] 1. Mooring float 2. Anchor for a single mooring line 3. Several mooring ropes 4. Mooring rope or part of a mooring rope 5 sea level 6. Seabed (mudline or ocean floor) 7. Fluid ropes, control ropes, and / or power ropes 8. General anchors 9. Connecting the mooring rope to the anchor. 10. Mooring rope connection points to mooring floats 11 Buoyancy elements 12 Floater buoyancy column 13 Flow Brace 14. A straight line between the anchor connection and the floater connection, viewed from above, on the outermost mooring rope on side 1 of the mooring cluster. 15. A straight line between the anchor connection and the floater connection, viewed from above, showing the outermost mooring rope on side 2 of the mooring cluster. 16. The outermost mooring rope (or a portion thereof) of the parallel or nearly parallel mooring ropes on side 1 of the mooring cluster. 17. The outermost mooring rope (or a portion thereof) of the parallel or nearly parallel mooring ropes on side 2 of the mooring cluster. 18. A straight line between the anchor connection and the floater connection, viewed from the side. 19 Devices for parallel or nearly parallel interconnections between anchor connections and floater connections 20 Mooring arrangement 21 Single mooring rope section 22. Virtual rope sling around the outermost point of the floating unit 23. Region inside the boundary defined by the virtual rope sling 24 Mooring Clusters 25 Lower part of mooring rope 26 Upper part of the mooring rope

Claims

1. A mooring arrangement (20) for mooring a floating unit (1) to the seabed (6), comprising a plurality of mooring clusters, each connectable to the floating unit (1), and anchors (3) adapted to the seabed (6), wherein at least one mooring cluster comprises at least two mooring lines (4a, 4b), A mooring arrangement (20) characterized in that the at least two mooring lines (4a, 4b) of the same mooring cluster are adapted to be connected to the same anchor.

2. The mooring arrangement (20) according to claim 1, wherein each of the at least two mooring lines (4a, 4b) is provided with a floating unit connection point (10, 10a, 10b) adapted to be connected to the floating unit (1), and the floating unit connection points (10, 10a, 10b) are arranged horizontally at intervals of less than 30 meters.

3. The mooring arrangement (20) according to claim 1 or 2, wherein the mooring ropes (4a, 4b) within the same mooring cluster are individual ropes separated along their length, and each anchor (3) has separate anchor connection points (9a, 9b) and each floating unit (1) has separate floating unit connection points (10a, 10b).

4. The mooring arrangement (20) according to claim 1 or 2, wherein the mooring ropes (4a, 4b) within the same mooring cluster are connected to each other by a connecting element (19) located between the anchor (3) and the floating unit (1).

5. The mooring arrangement (20) according to claim 4, further comprising a single mooring rope (21) between the anchor connection point (9) and the connecting element (19), wherein the length of the single mooring rope (21) and the connecting element (19) is less than 50% of the distance between the anchor connection point (9) and the floating unit connection points (10, 10a, 10b) on the floating unit (1).

6. The mooring arrangement according to any one of claims 1 to 5, wherein the arrangement comprises at least two mooring clusters, each mooring cluster comprising two mooring lines (4a, 4b, 4a', 4b') connectable to a common anchor (3), the first mooring cluster (24) comprising a first set of floating unit connection points (10a, 10b) connectable to a floating unit (1), the second mooring cluster (24') comprising a second set of floating unit connection points (10a', 10b') connectable to the floating unit (1), and the locations of the first set of floating unit connection points (10a, 10b) are different from those of the second set of floating unit connection points (10a', 10b') on the floating unit (1), so that none of the connection points coincide.

7. Each of the at least two mooring lines (4a, 4b) is provided with a floating unit connection point (10, 10a, 10b) adapted to connect to the floating unit (1), and the two floating unit connection points (10, 10a, 10b) are spaced apart by a first distance D1. The horizontal distance between the anchor connection point (9, 9a, 9b) of any of the at least two mooring ropes (4a, 4b) associated with the anchor (3) and any of the floating unit connection points (10, 10a, 10b) defines a second distance D2. The mooring arrangement (20) according to any one of claims 1 to 6, wherein the ratio D2 / D1 obtained by dividing the second distance by the first distance is greater than 5.

8. The mooring arrangement (20) according to any one of claims 1 to 7, wherein the arrangement comprises a separation angle A of less than 5 degrees, where A is defined as the angle between the first rope 14 and the second rope 15 that reflects the straight line in the horizontal plane between the anchor connection points (9, 9a, 9b) and the floating unit connection points (10, 10a, 10b) for the two outermost mooring ropes of the mooring cluster.

9. The mooring arrangement (20) according to any one of claims 1 to 8, wherein the arrangement comprises an angle B of less than 45 degrees, the angle B being defined by the angle between the horizontal axis and the straight line (18) between the lower and upper ends of the mooring ropes (4a, 4b, 4a', 4b').

10. A mooring system for mooring a floating unit (1) to the seabed (6), A mooring arrangement according to any one of claims 1 to 6, Floating unit (1), Anchor (3) and, A mooring system equipped with the following features.

11. The mooring system according to claim 10, wherein the system comprises at least two mooring clusters, each mooring cluster comprising two mooring lines (4a, 4b) connected to a common anchor (3), the first mooring cluster (24) comprising a first set of floating unit connection points (10a, 10b) connected to the floating unit (1), the second mooring cluster (24') comprising a second set of floating unit connection points (10a', 10b') connected to the floating unit (1), and the locations of the first set of floating unit connection points (10a, 10b) are different from the locations of the second set of floating unit connection points (10a', 10b') on the floating unit, so that the connection points do not coincide.

12. The mooring system according to claim 10 or 11, wherein the floating unit comprises at least two structurally connected floating elements (12, 12', 12''), and each mooring cluster (24, 24', 24'') is associated with each floating element (12, 12', 12'') of the floating unit (1).

13. The mooring system according to any one of claims 10 to 12, wherein the horizontal distance between the anchor connection points (9, 9a, 9b) of the at least two mooring ropes (4a, 4b) associated with the anchor (3) and the floating unit connection points (10, 10a, 10b) associated with the floating unit (1) is greater than 150 meters.

14. The mooring system according to any one of claims 10 to 13, wherein the angle between a vector (18) defined by a straight line between the anchor connection points (9, 9a, 9b) and the floater connection points (10, 10a, 10b) and a projection vector representing the projection of the vector (18) onto the seabed (6) is less than 45 degrees.

15. Each of the at least two mooring ropes (4a, 4b) is provided with a floating unit connection point (10, 10a, 10b) connected to the floating unit (1), and the two floating unit connection points (10, 10a, 10b) are spaced apart by a first distance D1. The horizontal distance between any of the anchor connection points (9, 9a, 9b) of the at least two mooring ropes (4a, 4b) connected to the anchor (3) and any of the floating unit connection points (10, 10a, 10b) defines a second distance D2. The mooring system according to any one of claims 10 to 14, wherein the ratio D2 / D1 obtained by dividing the second distance by the first distance is greater than 5.

16. The mooring system according to any one of claims 10 to 15, wherein the mooring cluster has a separation angle A of less than 5 degrees, where A is defined as the angle between the first rope 14 and the second rope 15 that reflects a straight line in the horizontal plane between the anchor connection point (9, 9a, 9b) and the floating unit connection point (10, 10a, 10b) for the two outermost mooring ropes of the mooring cluster.

17. The mooring system according to any one of claims 10 to 15, wherein the arrangement comprises an angle B of less than 45 degrees, the angle B being defined by the angle between the horizontal axis and the straight line between the lower and upper ends of the mooring ropes (4a, 4b, 4a', 4b').

18. The mooring system according to any one of claims 10 to 17, wherein the floating unit (1) is a floating wind turbine.

19. The mooring system according to any one of claims 10 to 18, wherein the floating unit (1) is a unit for oil and gas applications or other energy-related applications.

20. The mooring system according to any one of claims 10 to 19, wherein the floating unit (1) is a semi-submersible, ship-shaped, or barge-shaped unit.

21. The mooring system according to any one of claims 10 to 20, wherein the mooring cables (4a, 4b) within the same mooring cluster are identical in structure and length.

22. The mooring system according to any one of claims 10 to 21, wherein the mooring ropes (4) within the same mooring cluster differ in structure and length.

23. The mooring system according to any one of claims 10 to 22, wherein the anchor (3) shared by mooring lines (4a, 4b) from the same mooring cluster of the same floating unit (1) is also shared by mooring lines (4) from other floating units (1).

24. A method for setting up the mooring arrangement described in claims 1 to 9, or a mooring system described in claims 10 to 23, A method or mooring system in which the mooring lines (4a, 4b) within the same mooring cluster are installed parallel to and simultaneously between the anchor (3) and the floating unit (1).

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