Double-floating-body type offshore platform stabilizing system capable of eliminating anchoring vertical interference

Abstract

The invention discloses a double-floating-body type offshore platform stabilizing system capable of eliminating anchoring vertical interference. The system comprises a working platform, a stable buoy, a seabed ground anchor, a main anchor cable for connecting the ground anchor and the buoy, and a horizontal connecting cable for connecting the buoy and the platform. The stable buoy is designed to have excessive buoyancy, so that the stable buoy can completely bear the vertical component of the tension of the main anchor cable; the horizontal component of the main anchor cable is transmitted to the working platform through the horizontal connecting cable, and pure horizontal positioning force is provided. According to the design, the interference of the anchoring system on the vertical stability of the working platform is fundamentally eliminated, and the system is of a full-passive mechanical structure and is reliable and economical. And the method is particularly suitable for a precise offshore operation platform with strict requirements on the altitude height stability.

Description

Technical Field

[0001] This invention relates to the field of marine engineering technology, specifically to an anchoring and positioning system for floating offshore platforms, and more particularly to an innovative system that can decompose the anchor cable tension into a horizontal positioning force and a vertical buoyancy load, thereby eliminating the interference of the anchoring system on the vertical stability of the platform. Background Technology

[0002] Traditional floating work platforms are typically moored directly to the seabed using inclined anchor cables. While providing horizontal restoring force, these cables inevitably generate a vertical component of force. This vertical component alters the platform's draft, causing additional heaving motion in response to waves, tides, and changes in anchor cable tension, severely impacting the platform's elevation stability.

[0003] For precision offshore operations (such as laser mapping, satellite communication, and precision instrument monitoring), such height fluctuations are unacceptable. In particular, the "A Megawatt-Level Wave Power Generation Device with Two-Stage Wave Converter" (2025224927198) is highly sensitive to wave height. Existing solutions, such as active heave compensation systems, are costly and have limited reliability, while simply increasing the platform size is extremely uneconomical. Furthermore, automation technology, from sensors to microprocessors to actuators, requires time and introduces latency. Supported by the research papers "A Fully Electric Unmanned Multi-Legged Double-Head Reverse Helical Pile Driver for Low-Adhesion Environments and Its Collaborative Control Method" (2025120033595) and "A Helical Pile Group Anchoring System and Method Based on Force Decomposition Enhancement" (202610000045.1), we designed this zero-latency offshore platform stabilization system. Summary of the Invention

[0004] This invention provides an innovative dual-buoyancy mooring system that fundamentally solves the above-mentioned problems by having a dedicated buoy bear the vertical component of the anchor cable, allowing the work platform to only bear the horizontal positioning force.

[0005] The technical solution of the present invention is as follows: A stabilization system for a twin-buoy offshore platform that eliminates vertical disturbances during anchoring includes: - A work platform that floats on the sea surface to support equipment and operations; - Stabilizing buoys, which also float on the sea surface, are connected to the work platform via horizontal connecting cables; - Subsea anchor, fixed to the seabed; - Main anchor cable, connecting the seabed anchor to the stabilizing buoy.

[0006] The core innovation of the system lies in its mechanical decomposition mechanism: 1. Decomposition of force: The main anchor cable exerts a tilting tension on the stabilizing buoy due to the constraint of the seabed anchor. This tension can be decomposed into horizontal and vertical components.

[0007] 2. Vertical Force Balancing: The stabilizing buoy is designed with excess buoyancy (i.e., its net buoyancy is greater than its own weight), which is specifically used to balance the vertical downward component of the main anchor cable tension. Therefore, the vertical component of the anchor cable is completely contained within the stabilizing buoy and is not transmitted to the work platform through the horizontal connecting cable.

[0008] 3. Transmission of horizontal force: The horizontal component of the tension in the main anchor cable is transmitted to the working platform through the approximately horizontal connecting cable, providing it with a pure horizontal positioning and restoring force.

[0009] With this design, the working platform receives only horizontal positioning force from the mooring system, and its vertical movement is only affected by environmental loads (waves, wind, etc.), thus decoupling from the tension fluctuations of the mooring system and significantly improving the platform's altitude stability.

[0010] Preferably, the stabilizing pontoon adopts a high stability design to suppress its own heave, including: - Large-diameter draft section: The underwater part of the pontoon has a diameter significantly larger than that of the part above the waterline, so that its drainage volume is concentrated in the deep water area where the wave influence is less, and the buoyancy change caused by the wave accounts for a small proportion.

[0011] - Damping accessories: Multiple layers of horizontal damping plates are added to the underwater part of the pontoon to provide additional heave damping.

[0012] Furthermore, the horizontal connecting cable may be equipped with a tension adjustment device (such as a constant tension winch) or an elastic element to buffer dynamic loads and maintain the cable level.

[0013] The beneficial effects of this invention are: 1. Complete decoupling: Separating the vertical and horizontal components of the mooring force, the working platform is free from vertical interference from the mooring, providing a fundamental solution with zero delay for platform height stability.

[0014] 2. Passive stabilization: The entire system is a fully mechanical passive structure, requiring no active control, resulting in high reliability and low maintenance costs.

[0015] 3. Modular design: The stabilizing pontoons can be used as independent modules, which are easy to integrate with existing platforms and have low modification costs.

[0016] 4. High adaptability: By adjusting the excess buoyancy of the pontoon and the angle of the main anchor cable, it can adapt to different water depths, sea conditions and positioning force requirements. Attached Figure Description

[0017] Figure 1This is a schematic diagram of the overall layout and mechanical principles of the system of the present invention.

[0018] Figure 2 This diagram shows a mechanical comparison between a traditional single-platform mooring system and the present invention.

[0019] Figure 3 A cross-sectional view of a preferred embodiment for stabilizing the pontoon (with a large-diameter lower damping plate).

[0020] In the diagram: 10-Working platform, 20-Stabilizing buoy, 21-Upper small-diameter section of buoy, 22-Lower large-diameter section of buoy, 23-Horizontal damping plate, 30-Seabed anchor, 40-Main anchor cable, 50-Horizontal connecting cable, Fv-Vertical component of anchor cable, Fh-Horizontal component of anchor cable, Fbuoy-Excess buoyancy of buoy. Detailed Implementation

[0021] like Figure 1 As shown, both the working platform 10 and the stabilizing buoy 20 float on the sea surface and are connected by a horizontal connecting cable 50. The main anchor cable 40 connects the stabilizing buoy 20 to the seabed anchor 30. The angle between the main anchor cable 40 and the seabed is θ.

[0022] Design Example: Assume the horizontal positioning force required by the working platform is 80 kN, and the angle between the main anchor cable and the seabed is θ = 30°.

[0023] The tension of the main anchor cable is T = 80 / cos30° ≈ 92.4 kN.

[0024] The vertical component of the anchor cable force Fv = T sin30° = 46.2 kN.

[0025] Therefore, the stabilizing buoy 20 needs to have an excess buoyancy of at least 46.2 kN (approximately 4.7 tons).

[0026] The static tension of the horizontal connecting cable 50 is 80 kN, and theoretically there is no vertical component force.

[0027] like Figure 3 As shown, a preferred design for the stabilizing buoy 20 includes a cylindrical section 21 with a diameter of 1m and a height of 2m above the waterline to reduce the wind-exposed area; and a large-diameter section 22 with a diameter of 3m and a height of 4m below the waterline, placing most of the drainage volume in a water depth where wave influence is less. Two layers of horizontal damping plates 23 with a diameter of 4m and an opening ratio of 20% are installed at the bottom of the underwater section to suppress the buoy's own heaving.

[0028] When environmental loads cause the work platform 10 to deviate, the stabilizing buoy 20 is pulled by the horizontal connecting cable 50, and then the horizontal restoring force is obtained from the seabed anchor through the main anchor cable 40. During this process, the vertical component of the anchor cable is always balanced by the excess buoyancy of the stabilizing buoy 20, and will not affect the draft of the work platform 10.

[0029] This invention is not limited to the embodiments described above. For example, multiple such systems can be symmetrically arranged on a single work platform; the specific shape and damping design of the stabilizing buoys can be varied; and the connecting cables can be made of different materials. Any solution that adopts the core concept of "using independent buoys to bear the vertical component of the anchor cable, so that the work platform is only subjected to horizontal mooring forces" falls within the protection scope of this invention.

Claims

1. A stabilization system for a dual-floating offshore platform to eliminate vertical interference during anchoring, characterized in that, include: The work platform (10) floats on the sea surface; Stabilizing buoy (20) floats on the sea surface; Subsea anchor (30), fixed to the seabed; The main anchor cable (40) connects the seabed anchor (30) to the stabilizing buoy (20). A horizontal connecting cable (50) connects the stabilizing buoy (20) to the working platform (10). The stabilizing buoy (20) has excess buoyancy, which is configured to balance the vertical downward component of the tension of the main anchor cable (40), so that the horizontal connecting cable (50) applies only a horizontal positioning force to the working platform (10).

2. The system according to claim 1, characterized in that, The underwater portion of the stabilizing buoy (20) has a significantly larger diameter than its above-water portion, so that most of its drainage volume is located at a water depth where wave influence is minimal.

3. The system according to claim 2, characterized in that, The above-water portion of the stabilizing buoy (20) is a slender columnar structure; under the designed sea conditions of the platform, its top elevation is higher than the maximum wave crest elevation, and the elevation at the junction of its connection with the underwater large-diameter portion is lower than the minimum wave trough elevation.

4. The system according to claim 1 or 2, characterized in that, The underwater portion of the stabilizing buoy (20) is equipped with one or more horizontal damping plates (23).

5. The system according to claim 4, characterized in that, The horizontal damping plate (23) has drag-reducing holes.

6. The system according to claim 1, characterized in that, The horizontal connecting cable (50) is made of a material with a density close to that of seawater.

7. The system according to claim 1, characterized in that, At least three subsystems as described in any one of claims 1-5 are symmetrically arranged around the work platform (10).

8. The system according to claim 1, characterized in that, The mooring points at both ends of the horizontal connecting cable (50) on the working platform (10) and the stabilizing buoy (20) are at a depth underwater that is not affected by wave pressure waves, and the two mooring points are as close to the same horizontal line as possible.

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