Protective laying method for deep-water mooring lines

Abstract

The present invention discloses a method for protective laying of deepwater mooring cables, comprising the following steps: when an engineering vessel lays an anchor chain to the end, the anchor chain is fixed to the stern of the engineering vessel by a shark clamp, a steel cable and a working winch are connected to the anchor chain limit, and the shark clamp is opened to lower the steel cable; the steel cable is lifted out of the stern and lowered into the water by a crane, the connection between the crane and the steel cable is disconnected, and the steel cable and the working winch are synchronously lowered to lower the anchor chain; the crane is connected to the anchor chain at a mid-water position, the anchor chain load is transferred to the crane, and the connection between the working winch and the anchor chain is disconnected; the crane rotates toward the side of the engineering vessel and changes its amplitude to increase the distance between the anchor chain and the steel cable; the engineering vessel lowers the steel cable, and the crane lowers the anchor chain synchronously with the anchor chain, keeping the anchor chain load acting on the crane, thereby completing the protective laying of the steel cable. The present invention reduces the stress load on the steel cable during the laying process of the deepwater mooring cable, avoids destructive damage to the steel cable due to excessive load, and increases the service life of the steel cable.

Description

Technical Field

[0001] The present invention relates to the technical field of submarine cable laying, and in particular to a protective laying method for deep-water mooring cables. Background Art

[0002] The development model of floating facilities plus underwater production systems is often regarded as the preferred solution for deepwater oil and gas field development due to its good economic performance. Floating facilities rely on a single-point or multi-point mooring system to fix them at sea and continuously provide services to oil and gas fields, and can even be untied during typhoons. When laying the mooring legs of the floating facility mooring system, the anchor chain is usually lowered first, and then the end of the anchor chain is connected to the head of the steel cable on the deck, and then the steel cable is lowered, and the connection and laying of each component of the anchor leg are completed in sequence. However, when entering deep water, due to the significant increase in water depth, when laying the steel cable, the weight of the anchor chain in the water is too large, exceeding the maximum load that the steel cable can withstand when it is coiled on the drum. If this method is used for laying, the steel cable will suffer destructive damage due to the excessive load, affecting the service life of the steel cable. Therefore, measures must be taken to reduce the load when laying the steel cable to achieve the purpose of protective laying. Summary of the Invention

[0003] The purpose of the present invention is to provide a protective laying method for deep-water mooring cables, which reduces the stress load on the steel cables during the laying process of the deep-water mooring cables, avoids destructive damage to the steel cables due to excessive load, and increases the service life of the steel cables.

[0004] To achieve the object of the present invention, the present invention provides a method for protectively laying a deep-water mooring cable, comprising the following steps:

[0005] S1. When the engineering vessel has laid the anchor chain to the end, the anchor chain is fixed to the stern of the engineering vessel using a shark clamp. After the steel cable and the working winch are connected to the anchor chain, the shark clamp is opened to lower the steel cable.

[0006] S2. Use a crane to lift the steel cable out from under the stern and put it into the water, untie the connection between the crane and the steel cable, and use the steel cable and working winch to synchronously lower the anchor chain;

[0007] S3, the crane is connected to the anchor chain at the mid-water position, the anchor chain load is transferred to the crane, and the connection between the working winch and the anchor chain is released;

[0008] S4, the crane rotates toward the side of the engineering vessel and changes its amplitude to increase the distance between the anchor chain and the steel cable;

[0009] S5. The engineering vessel lowers the steel cable, and the crane lowers the anchor chain synchronously, keeping the anchor chain load acting on the crane, thereby completing the protective laying of the steel cable.

[0010] As a preferred technical solution of the present invention, the steel cable is released from the anchor drum of the engineering vessel and connected to the anchor chain through a connector. The working winch is connected to the anchor chain through a rigging, and the working winch belt force bears the weight of the anchor chain.

[0011] As a preferred technical solution of the present invention, the crane lifts the connecting piece, and at the same time the working winch and the steel cable are slowly lowered, and the knot head of the steel cable is protectively placed under the stern drum into the water.

[0012] As a preferred technical solution of the present invention, the engineering ship reclaims the working winch to the deck, and the crane rotates toward the starboard side of the ship to increase the horizontal distance between the anchor chain and the steel cable, reduce the crane lifting radius, and increase the crane lifting capacity.

[0013] As a preferred technical solution of the present invention, when the connection between the crane and the anchor chain is lowered to the seabed, the laying is suspended, the connection between the crane and the anchor chain is untied by ROV, and the engineering vessel recovers the crane to the water surface to complete the protective laying of the steel cable.

[0014] Compared with the prior art, the present invention provides a method for protective laying of deep-water mooring cables, which has the following beneficial effects:

[0015] After the engineering vessel lowers the mooring anchor chain, it uses a shark clamp to lock the anchor chain to the aft deck. The mooring cable is released from the anchor drum and connected to the anchor chain via a connector. The engineering vessel's working winch is connected to the anchor chain via rigging. The working winch bears the weight of the anchor chain. The shark clamp is opened, and the cable is ready to be lowered. The engineering vessel's crane hoists the connecting piece between the cable and the anchor chain. Simultaneously, the working winch and cable are slowly lowered, and the cable knot is protectively lowered under the stern drum. The crane is then released. The engineering vessel's crane re-enters the water and connects to the anchor chain at mid-water depth. It applies force, transferring the weight of the anchor chain from the working winch to the crane, and then releases the connection between the working winch and the anchor chain. The working winch is then retrieved and returned to the engineering vessel's deck. The crane is then rotated to the starboard side of the ship to increase the horizontal distance between the anchor chain and the cable to prevent underwater entanglement. Simultaneously, the crane's luffing is reduced to reduce the lifting radius, thereby increasing the crane's lifting capacity. The ROV monitored the entire construction process underwater. At this point, the majority of the anchor chain's weight was transferred to the vessel's crane, leaving a relatively light load on the mooring cable. The vessel's anchor drum rotated to release the mooring cable, while the crane simultaneously lowered the anchor chain. The vessel then maneuvered along the designed anchor leg path, ensuring a protective lowering of the cable. When the connection between the crane and the anchor chain reached the seabed, the laying process was paused, and the ROV released the crane from the anchor chain and retrieved the crane to the surface. At this point, the cable, bearing only its own weight and relatively light load, could be lowered directly to the seabed. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the connection between the working winch and the anchor chain of the present invention;

[0017] Figure 2 This is a schematic diagram of the protective entry of the steel cable into water according to the present invention;

[0018] Figure 3 This is a schematic diagram of the underwater connection between the crane and the anchor chain of the present invention;

[0019] Figure 4 This is a schematic diagram of the distance between the crane and the steel cable of the present invention;

[0020] Figure 5 This is a schematic diagram of the protective lowering of the steel cable of the present invention;

[0021] Figure 6 It is a schematic diagram of untying the connection between the crane and the anchor chain according to the present invention.

[0022] 1 is the engineering vessel, 2 is the working winch, 3 is the connector, 4 is the rigging, 5 is the anchor chain, 6 is the steel cable, 7 is the crane, and 8 is the ROV. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] See also Figures 1-6 , an embodiment of the present invention provides a method for protective laying of deep-water mooring cables, comprising the following steps:

[0025] S1. When the engineering vessel 1 lays the anchor chain 5 to the end, the anchor chain 5 is fixed to the stern of the engineering vessel 1 by a shark clamp. After the steel cable 6 and the working winch 2 are connected to the anchor chain 5, the shark clamp is opened to lower the steel cable 6.

[0026] S2, hoisting the steel cable 6 out from the stern and into the water by means of the crane 7, untying the connection between the crane 7 and the steel cable 6, and lowering the anchor chain 5 synchronously with the steel cable 6 and the working winch 2;

[0027] S3, the crane 7 is connected to the anchor chain 5 at the mid-water position, the load of the anchor chain 5 is transferred to the crane 7, and the connection between the working winch 2 and the anchor chain 5 is untied;

[0028] S4, the crane 7 rotates toward the side of the engineering vessel 1 and changes its amplitude, increasing the distance between the anchor chain 5 and the steel cable 6;

[0029] S5. The engineering vessel 1 lowers the steel cable 6, and the crane 7 lowers the anchor chain 5 synchronously, keeping the load of the anchor chain 5 acting on the crane 7, thereby completing the protective laying of the steel cable 6.

[0030] In one embodiment of the present invention, the steel cable 6 is released from the anchor drum of the engineering vessel 1 and connected to the anchor chain 5 through the connector 3. The working winch 2 is connected to the anchor chain 5 through the rigging 4. The working winch 2 bears the weight of the anchor chain 5 with force.

[0031] In one embodiment of the present invention, the crane 7 lifts the connector 3, while the working winch 2 and the steel cable 6 are slowly lowered, and the knot head of the steel cable 6 is protectively lowered into the water through the stern drum.

[0032] In one embodiment of the present invention, the engineering vessel 1 retracts the working winch 2 to the deck, and the crane 7 rotates toward the starboard side of the ship to increase the horizontal distance between the anchor chain 5 and the steel cable 6, thereby reducing the lifting radius of the crane 7 and increasing the lifting capacity of the crane 7.

[0033] In one embodiment of the present invention, when the connection between the crane 7 and the anchor chain 5 is lowered to the seabed, the laying is suspended, the connection between the crane 7 and the anchor chain 5 is untied by ROV8, and the engineering vessel 1 recovers the crane 7 to the water surface to complete the protective laying of the steel cable 6.

[0034] The above are only preferred specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solutions and inventive concepts of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for protective laying of deep-water mooring lines, characterized in that: The following steps are involved: S1. When the engineering vessel (1) lays the anchor chain (5) to the end, the anchor chain (5) is fixed to the stern of the engineering vessel (1) by means of a shark clamp, and after the steel cable (6) and the working winch (2) are connected to the anchor chain (5) in a limited manner, the shark clamp is opened to lower the steel cable (6); S2, lifting the steel cable (6) from the stern of the ship and placing it into the water by means of a crane (7), untying the connection between the crane (7) and the steel cable (6), and lowering the anchor chain (5) synchronously with the steel cable (6) and the working winch (2); S3, the crane (7) is connected to the anchor chain (5) at the mid-water position, the load of the anchor chain (5) is transferred to the crane (7), and the connection between the working winch (2) and the anchor chain (5) is untied; S4, the crane (7) rotates toward the side of the engineering ship (1) and changes its amplitude, thereby increasing the distance between the anchor chain (5) and the steel cable (6); the engineering ship (1) retracts the working winch (2) to the deck; the crane (7) rotates toward the starboard side of the ship to increase the horizontal distance between the anchor chain (5) and the steel cable (6), thereby reducing the lifting radius of the crane (7) and increasing the lifting capacity of the crane (7); S5. The engineering vessel (1) lowers the steel cable (6), and the crane (7) lowers the anchor chain (5) synchronously, keeping the load of the anchor chain (5) acting on the crane (7), thereby completing the protective laying of the steel cable (6).

2. A method for protective laying of deepwater mooring lines according to claim 1, characterized in that: In step S1, the steel cable (6) is released from the anchor drum of the engineering vessel (1) and connected to the anchor chain (5) through a connector (3); the working winch (2) is connected to the anchor chain (5) through a rigging (4); and the working winch (2) bears the weight of the anchor chain (5) with a force.

3. A method for protective laying of deepwater mooring lines according to claim 2, characterized in that: In step S2, the crane (7) lifts the connector (3), while the working winch (2) and the steel cable (6) are slowly lowered, and the knot head of the steel cable (6) is protectively placed under the stern drum into the water.

4. A method for protective laying of deepwater mooring lines according to claim 1, characterized in that: In step S5, when the connection between the crane (7) and the anchor chain (5) is lowered to the seabed, the laying is suspended, the connection between the crane (7) and the anchor chain (5) is untied by the ROV (8), and the engineering vessel (1) recovers the crane (7) to the water surface to complete the protective laying of the steel cable (6).

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