Offshore semi-submersible platform, anchoring system and anchor chain and tension balancing method thereof

Abstract

The invention discloses an offshore semi-submersible platform, an anchoring system and an anchor chain and a tension balancing method thereof. The anchor chain comprises an anchor chain body and at least one tension balancing assembly arranged on the anchor chain body. The tension balancing assembly comprises a safety section, detachable connectors arranged at the two opposite ends of the safety section, and a lengthening section connected between the two connectors. The length of the lengthening section is greater than that of the safety section; the safety section is connected into the anchor chain body through the two connectors to form a part of the anchor chain body in the length direction. And the lengthening section is hung on the anchor chain main body relative to the safety section. The anchor chain of the anchoring system is simple, reliable and convenient to install, and external energy sources such as hydraulic pressure and electric power are not needed; no movable part is arranged, so that large load can be borne; tension can be automatically balanced according to the wind wave flow direction, and manual operation is not needed after installation.

Description

Technical Field

[0001] The present invention relates to the technical field of marine mooring systems, and in particular to an offshore semi-submersible platform, a mooring system, an anchor chain and a tension balancing method thereof. Background Art

[0002] Floating marine engineering structures such as semi-submersible platforms and floating wind turbines have been widely used in the field of marine engineering. Such structures float on the ocean for a long time. In order to resist the effects of external environmental conditions, multi-point mooring systems are usually used for positioning, such as Figure 1 As shown in the figure. The mooring system is a key system to limit the movement of floating structures with the waves, achieve positioning, and ensure safety. However, the coastal areas are affected by typhoons every summer and autumn, and the environmental conditions are very harsh, resulting in accidents in which the mooring system fails.

[0003] During the layout phase of the floating structure mooring system, since it is impossible to accurately predict the direction of extreme storms (such as typhoons), a symmetrical anchoring scheme is usually adopted, which is characterized by the overall coverage of the anchor system layout at 360°, and each anchor chain is distributed at a certain regular interval, forming a symmetrical layout relative to the front, back, left and right of the hull. The advantage of this layout is that the tension of the anchor chain in each direction is roughly the same, which is especially suitable for sea areas with unstable wind and wave directions. However, at the same time, due to the dispersed anchoring angles, the tension distribution between the anchor chains is uneven.

[0004] Under long-term and complex marine dynamic environment conditions, the tension of the mooring system exceeds the design threshold, which is one of the main causes of accidents in offshore platform mooring systems. In special environments such as typhoons, complex wind and wave conditions at sea may cause the mooring force to be concentrated on part of the anchor chain, causing the anchor chain or related connection structures to be damaged. The subsequent chain reaction may cause serious disasters such as offshore platform drift. In order to improve the safety of distributed mooring systems in different harsh offshore environments and deep-water large floating platforms, it is necessary to solve the problem of uneven tension between anchor chains under extreme external environmental conditions. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an anchoring system capable of balancing tension, an anchor chain thereof, a balancing method and an offshore semi-submersible platform having the anchoring system.

[0006] The technical solution adopted by the present invention to solve the technical problem is: to provide an anchor chain of an anchoring system, comprising an anchor chain body, and at least one group of tension balancing components arranged on the anchor chain body;

[0007] The tension balance assembly includes a safety section, detachable joints arranged at opposite ends of the safety section, and an extension section connected between the two joints; the length of the extension section is greater than the length of the safety section;

[0008] The safety section is connected to the anchor chain body through the two joints, forming a part of the anchor chain body in the length direction; the extension section is hung on the anchor chain body relative to the safety section.

[0009] Preferably, the rated tension of the safety section is smaller than the rated tension of the anchor chain body.

[0010] Preferably, the rated tension of the extension section is not less than the rated tension of the anchor chain body.

[0011] Preferably, the anchor chain comprises a plurality of groups of the tension balancing components, and the plurality of groups of the tension balancing components are serially connected to the anchor chain body.

[0012] Preferably, the anchor chain further comprises an anchor head, and the anchor head is arranged at one end of the anchor chain body.

[0013] The present invention also provides an anchoring system, comprising a plurality of anchor chains as described in any one of the above items;

[0014] A plurality of anchor chains are distributed at intervals along the circumference of the floating marine structure, connected between the floating marine structure and the seabed, so as to float and position the floating marine structure on the sea.

[0015] The present invention also provides an offshore semi-submersible platform, comprising a platform body and an anchoring system, wherein the anchoring system floats and positions the platform body on the sea;

[0016] The mooring system comprises a plurality of anchor chains, which are evenly distributed at four corners of the platform body. At each corner of the platform body, one or at least two anchor chains are connected between the platform body and the seabed at a predetermined angle.

[0017] The present invention also provides a tension balancing method for an anchoring system, comprising:

[0018] In a harsh environment, when the tension of at least one anchor chain of the mooring system reaches a maximum value, the safety section on the anchor chain is disconnected under the action of external force, and the extension section replaces the safety section to form a part of the length of the anchor chain, and the length of the anchor chain is increased, so that the load on the anchor chain is adjusted to other anchor chains.

[0019] The beneficial effects of the present invention are as follows: by connecting the safety section and the extension section in series in the anchor chain, the extension section can replace the safety section when the safety section is disconnected, and the anchor chain is lengthened, the anchor chain load is automatically adjusted to other anchor chains, the tension peak is reduced, and the safety of the mooring system is ensured.

[0020] The present invention has a simple and reliable structure, is easy to install, and does not require external energy sources such as hydraulics and electricity; it has no moving parts and can withstand a large load; it can automatically balance the tension according to the direction of wind, waves and currents, and does not require manual operation after installation. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0022] Figure 1 It is a schematic diagram of positioning of a multi-point mooring system in the prior art;

[0023] Figure 2 is a schematic structural diagram of an anchoring system according to an embodiment of the present invention;

[0024] Figure 3 It is a schematic diagram of the structure of an anchor chain in an anchoring system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0026] like Figure 2 and Figure 3 As shown, an anchoring system according to an embodiment of the present invention comprises a plurality of anchor chains 2; the plurality of anchor chains 2 are distributed at intervals along the circumference of the floating marine structure 1, connected between the floating marine structure 1 and the seabed, so as to float and position the floating marine structure 1 at sea.

[0027] The floating marine structure 1 can be any structure that needs to float in the seawater, including a semi-submersible platform, a floating wind power plant, and the like.

[0028] The anchor chain 2 includes an anchor chain body 20, at least one group of tension balancing components 4 and an anchor head 3. The tension balancing components 4 are connected in series in the anchor chain body 20. The anchor head 3 is arranged at one end of the anchor chain body 20 for embedding in the seabed to achieve tensioning of the anchor chain.

[0029] Further, the tension balance assembly 4 includes a safety section 41, an extension section 43 and two detachable joints 42. The two joints 42 are arranged at opposite ends of the safety section 41, and the safety section 41 is connected to the anchor chain body 20 through the two joints 42, constituting a part of the length direction of the anchor chain body 20. The extension section 43 is connected between the two joints 42 and is located on one side of the safety section 41.

[0030] The joint 42 may be, but is not limited to, a U-shaped joint.

[0031] The length of the extension section 43 is greater than the length of the safety section 41, so that on the anchor chain 2, the extension section 43 is hung on the anchor chain body 20 relative to the safety section 41. Figure 3 Status shown.

[0032] In terms of rated tension setting, the rated tension of the insurance section 42 is less than the rated tension of the anchor chain body 20, and the rated tension of the extension section 43 is not less than the rated tension of the anchor chain body 20. When the tension of the insurance section 42 is greater than its rated tension, it is disconnected, and the extension section 43 can replace the insurance section 41.

[0033] In some embodiments, the anchor chain 2 includes a plurality of tension balancing components 4, and the plurality of tension balancing components 4 are serially connected to the anchor chain body 20.

[0034] When the mooring system of the present invention is applied to an offshore semi-submersible platform, the offshore semi-submersible platform comprises a platform body and the mooring system, and the mooring system floats and positions the platform body on the sea.

[0035] The platform body is a semi-submersible platform, which is a type of floating marine structure 1. The platform body is connected to the seabed by a plurality of anchor chains 2, so that the platform body is floated and positioned on the sea.

[0036] In one embodiment, reference Figure 2 As shown, the mooring system of the offshore semi-submersible platform includes eight anchor chains 2, which are evenly distributed at four corners of the platform body. At each corner of the platform body, two anchor chains 2 are connected between the platform body and the seabed at a predetermined angle.

[0037] It is understandable that the anchor chains 2 of the offshore semi-submersible platform are not limited to the above eight, and can be increased or decreased according to actual needs. Each corner of the platform body can be connected to the seabed for positioning by one, two or more anchor chains 2.

[0038] Combination Figure 2 and Figure 3 A tension balancing method for an anchoring system according to an embodiment of the present invention may include:

[0039] In a harsh environment, when the tension of at least one anchor chain 2 of the mooring system reaches a maximum value, the safety section 41 on the anchor chain 2 is disconnected under the action of external force, and the extension section 43 replaces the safety section 41 to constitute a part of the length of the anchor chain 2, and increases the length of the anchor chain 2, so that the load on the anchor chain 2 is adjusted to other adjacent anchor chains 2.

[0040] Specifically, in the case where no disconnection occurs, the structure of the anchor chain 2 in the length direction (also the tension direction) includes the anchor chain body 20 and the safety section 41. Since the rated tension of the safety section 41 is less than the rated tension of the anchor chain body 20, it is the weakest part of the entire mooring system. Under the action of external force conditions, the safety section 41 will be disconnected first. After the safety section 41 is disconnected, the structure of the anchor chain 2 in the length direction (also the tension direction) includes the anchor chain body 20 and the extension section 43. This process increases the length of the anchor chain 2, automatically adjusts the load to other adjacent anchor chains 2, reduces the tension of the anchor chain 2, and reduces the risk of damage to the mooring system.

[0041] The present invention will be further described below by taking a specific offshore semi-submersible platform as an application case.

[0042] The offshore semi-submersible platform uses 8 R6 anchor chains for positioning, and the breaking force of a single anchor chain is 980t. A tension balance assembly is installed on each anchor chain. In this case, the insurance section uses R6 anchor chain with a breaking force of 950t and a length of 20-25m; the extension section is R6 anchor chain with a breaking force of 980t and a length of 30m.

[0043] The installation steps are as follows:

[0044] Step 1: Pull the anchor chain out of the anchor chain locker through the working boat and drop the anchor head at the predetermined location.

[0045] Step 2: Disconnect the anchor chain near the water surface and install the detachable connector.

[0046] Step 3: Install the safety section and extension section between the detachable joints.

[0047] Step 4: Repeat the above steps to complete the anchoring and component installation of all anchor chains.

[0048] Step 5: Start the anchor machine to pull the anchor until the pre-tension meets the requirements.

[0049] When an offshore semi-submersible platform encounters a typhoon and moves away from the anchor point under the action of environmental loads such as wind and waves, the tension on the windward side anchor chain gradually increases. If the anchor chain is not equipped with a tension balance component, when the tension of a certain anchor chain exceeds the maximum allowable tension (such as 980 tons), it will break, which will cause the platform displacement to continue to increase, and the tension of other anchor chains will continue to increase, which may lead to the failure of the entire mooring system and platform drift; in the case of a tension balance component installed on the anchor chain, when the tension of a certain anchor chain exceeds less than the maximum allowable tension (such as 950 tons), the insurance section will be disconnected first, and the length of the anchor chain will increase by 5-10m under the action of the extension section. Due to the change in length, the tension of part of the anchor chain is shared by the two adjacent anchor chains, reducing the peak tension and ensuring the safety of the mooring system.

[0050] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An anchor chain for an anchoring system, characterized in that: It comprises an anchor chain body and at least one group of tension balancing components arranged on the anchor chain body; The tension balance assembly includes a safety section, detachable joints arranged at opposite ends of the safety section, and an extension section connected between the two joints; the length of the extension section is greater than the length of the safety section; The safety section is connected to the anchor chain body through the two joints, forming a part of the anchor chain body in the length direction; the extension section is hung on the anchor chain body relative to the safety section.

2. The anchor chain of the mooring system according to claim 1, characterized in that: The rated tension of the safety section is less than the rated tension of the anchor chain body.

3. The anchor chain of the mooring system according to claim 2, characterized in that: The rated tension of the extension section is not less than the rated tension of the anchor chain body.

4. The anchor chain of the mooring system according to any one of claims 1 to 3, characterized in that: The anchor chain comprises a plurality of groups of tension balancing components, and the plurality of groups of tension balancing components are serially connected to the anchor chain body.

5. The anchor chain of the mooring system according to any one of claims 1 to 3, characterized in that: The anchor chain further comprises an anchor head, which is arranged at one end of the anchor chain body.

6. An anchoring system, characterized in that: Comprising a plurality of anchor chains according to any one of claims 1 to 5; A plurality of anchor chains are distributed at intervals along the circumference of the floating marine structure, connected between the floating marine structure and the seabed, so as to float and position the floating marine structure on the sea.

7. An offshore semi-submersible platform, characterized in that: The platform comprises a platform body and the mooring system according to claim 6, wherein the mooring system floats and positions the platform body at sea; The mooring system comprises a plurality of anchor chains, which are evenly distributed at four corners of the platform body. At each corner of the platform body, one or at least two anchor chains are connected between the platform body and the seabed at a predetermined angle.

8. A tension balancing method for an anchoring system according to claim 6, characterized in that: include: In a harsh environment, when the tension of at least one anchor chain of the mooring system reaches a maximum value, the safety section on the anchor chain is disconnected under the action of external force, and the extension section replaces the safety section to form a part of the length of the anchor chain, and the length of the anchor chain is increased, so that the load on the anchor chain is adjusted to other anchor chains.

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