Docking method suitable for cylindrical FPSO

Abstract

The invention discloses an undocking method suitable for a cylindrical FPSO (floating production storage and offloading), which comprises the following steps: S1, mooring and marking in a dock, and arranging a scheme according to a towing cable and rigging of the cylindrical FPSO in the dock; s2, balance weight load adjustment; s3, floating and leveling; s4, guiding the ship in the dock; s5, the dock gate is moored; s6, driving a main tug; s7, guiding the ship out of the dock; and S8, guiding the ship in the harbor basin. According to the undocking method suitable for the cylindrical FPSO, the cylindrical FPSO is guided to be undocked, so that the problems that a cylindrical structure is difficult to balance and adjust and easy to rotate in the undocking process are solved, and the difficulty that the distance between a bottom zigzag damping plate and a dock wall is difficult to observe underwater is effectively overcome; compared with the prior art, the safety of the cylindrical FPSO undocking process is remarkably enhanced, meanwhile, the working efficiency is greatly improved, and therefore safe and efficient undocking of the cylindrical FPSO is achieved, and the overall quality of undocking operation is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of marine floating platform construction, and in particular relates to an undocking method suitable for a cylindrical FPSO. Background Art

[0002] FPSO, as an offshore oil production platform integrating oil and gas production, storage, processing and external transmission, is moving from shallow waters to deep waters with the deepening of marine oil and gas development. In this process, cylindrical FPSO has received extensive attention and application in the field of offshore oil production due to its excellent stability, flexibility, economy and efficient space utilization. However, the construction process of cylindrical FPSO faces unique challenges, especially in the undocking operation. Due to its special cylindrical shape and large volume, it faces technical difficulties such as stability control, counterweight adjustment, and ship piloting in the dock. Although domestic and foreign scholars have conducted extensive theoretical research and practical exploration on the undocking method of ship-type FPSO and achieved remarkable results, these traditional undocking schemes are not completely applicable to cylindrical FPSO.

[0003] At present, cable layout and coordination with power equipment are required to ensure the stability and safety of cylindrical FPSO during undocking. In addition, due to the large size of cylindrical FPSO, counterweight adjustment is another technical challenge. The counterweight of the device must be accurately calculated and adjusted to ensure its buoyancy in the water. The maximum diameter of the cylindrical FPSO is located at the damping plate at its bottom. Since the damping plate of the cylindrical FPSO is below the water surface when undocking, it is difficult for operators to observe its exact position, so it is impossible to accurately estimate the size of the gap between the damping plate and the dock wall. It is precisely because of this uncertainty that the difficulty of undocking of cylindrical FPSO is further increased.

[0004] Therefore, it is urgent to design a method for undocking a cylindrical FPSO to solve the above-mentioned problems of difficulty in undocking and low working efficiency of the cylindrical FPSO. Summary of the invention

[0005] In order to solve the technical problems of great difficulty and low working efficiency in undocking of a cylindrical FPSO mentioned in the background technology, a method for undocking a cylindrical FPSO is provided to solve the above problems.

[0006] To achieve the above-mentioned purpose, the specific technical solution of the undocking method applicable to the cylindrical FPSO of the present invention is as follows: A method for undocking a cylindrical FPSO includes the following steps: S1. Cables and markings in the dock. According to the layout plan of the towing cable rigging of the cylindrical FPSO in the dock, the mooring short cable is tied to the mooring eye plate and LUG tube of the cylindrical FPSO shell in advance, and the cable layout is based on the undocking plan, and it is connected to the boat guide trolley and winch. At the same time, rubber fenders are arranged on both sides of the serrated damping plate at the bottom of the cylindrical FPSO near the dock wall, and several eye-catching colored flags are pulled to observe the actual position of the outer contour in the water; S2. Adjust the load with counterweight, place the submersible pump into the seawater, connect the water pipe to each ballast tank of the cylindrical FPSO, fill the tank with water to the designed depth, and then the diver will check the water tightness of the tank; S3, float and level, gradually release water to the dock to the draft depth of the cylindrical FPSO, check the water tightness of the cylindrical FPSO shell, and observe the floating state of the cylindrical FPSO hull. If the hull is not level after floating, fill it with water to level it, and continue to release water to the dock until the cylindrical FPSO floats to the preset height from the dock; S4. Pilot the ship in the dock, coordinate with the pilot trolley, winch, mooring bollard and the berthing point of the cylindrical FPSO cylinder system, and drag the cylindrical FPSO to the designated position in front of the dock threshold; S5, the dock gate is started to moor, the dock gate is connected to the two tugboats through cables, and the dock gate is towed to the designated location of the wharf for mooring; S6, with the main tugboat, connect the mooring short cable of the FPSO with the main tugboat cable, and use the trolley and winch to control the floating posture of the cylindrical FPSO; S7, the main tugboat, the tugboat towing hook, the winch and the mooring bollard cooperate with each other to tow the cylindrical FPSO out of the dock to the harbor; S8, piloting in the harbor, using a small boat with a cable to connect the auxiliary tugboat cable with the short mooring cable of the cylindrical FPSO in the harbor, based on the main towing force provided by the main tugboat and the lateral towing force provided by the auxiliary tugboat, assist in controlling the undocking direction of the cylindrical FPSO, the winch assists the rotation of the cylindrical FPSO, and the pilot trolley hook and winch cable are unhooked in time to ensure the safe undocking of the cylindrical FPSO.

[0007] Furthermore, when the cylindrical FPSO counterweight is adjusted, water release must be stopped every time the water in the cabin reaches a certain depth, and divers must be arranged to enter each cabin to observe the watertightness of the cabin. This cycle continues until the cabin is filled with water to the designed water depth.

[0008] Furthermore, for mooring at the dock gate, a mooring short cable needs to be pre-hung on the lifting lug 35 of the dock gate in advance, and when the tugboat is in place, the tugboat towing cable of the tugboat is connected to the mooring short cable of the dock gate to realize the mooring operation of the dock gate.

[0009] Furthermore, when bringing a main tugboat, it is necessary to use shackles to tie the mooring short cable into a figure-eight cable form on the mooring eye plate and LUG tube on the cylindrical FPSO shell in advance, and place the shackle at the end of the figure-eight cable on the water surface to facilitate the connection of the tugboat cable after the main tugboat is in place.

[0010] Furthermore, the ship is guided in the dock, with the guiding trolley as the main towing force of the cylindrical FPSO, and the winch assists in controlling its forward moving direction out of the dock.

[0011] Furthermore, the ship is guided out of the dock, with the main tugboat as the main towing force of the cylindrical FPSO, the towing hook of the ship-guided trolley mainly controlling the rotation, and the winch auxiliary controlling the rotation of the cylindrical FPSO.

[0012] Furthermore, there are four boat-guiding trolleys, two of which are symmetrically arranged on both sides of the dock, and six winches, three of which are symmetrically arranged on both sides of the dock, and the winch arranged in the middle is a temporary winch.

[0013] Furthermore, the height of the mooring short cable on the cylindrical FPSO cylinder connected by the trolley towing hook is 12m, and the height of the mooring short cable on the cylindrical FPSO cylinder connected by the winch is 21m.

[0014] Furthermore, the rubber fender installed at the position of the sawtooth damping plate at the bottom of the cylindrical FPSO is cylindrical and is fixed to the sawtooth damping plate at four points.

[0015] Furthermore, the leveling of the cylindrical FPSO is such that the draft difference at the four corners of the hull is no more than 300 mm.

[0016] The undocking method applicable to a cylindrical FPSO of the present invention has the following advantages: By guiding the cylindrical FPSO to undock, not only the problem that the cylindrical structure is difficult to balance and adjust and easy to rotate during the undocking process is solved, but also the difficulty of observing the distance between the bottom serrated damping plate and the dock wall underwater is effectively overcome. The safety of the cylindrical FPSO undocking process has been significantly enhanced, and the work efficiency has also been greatly improved, so that the cylindrical FPSO can be undocked safely and efficiently, improving the overall quality of the undocking operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a flow chart of the method for undocking a cylindrical FPSO according to the present invention; Figure 2 It is a schematic structural diagram of the towing cable rigging arrangement of the cylindrical FPSO in the dock of the present invention; Figure 3 It is a partial structural schematic diagram of the towing cable rigging arrangement of the cylindrical FPSO in the dock of the present invention; Figure 4It is a schematic diagram of the outline of the cylindrical FPSO sawtooth damping plate of the present invention; Figure 5 It is a structural schematic diagram of the mooring short cable connection of the cylindrical FPSO cylinder mooring eye plate of the present invention; Figure 6 It is a schematic structural diagram of the mooring short cable connection of the cylindrical FPSO cylinder LUG pipe of the present invention; Figure 7 It is a structural schematic diagram of the arrangement of the rubber fender of the sawtooth damping plate at the bottom of the cylindrical FPSO of the present invention; Figure 8 It is a partial structural schematic diagram of the arrangement of the rubber fender of the sawtooth damping plate at the bottom of the cylindrical FPSO of the present invention; Fig. 9 It is a schematic diagram of the structure of fixing the rubber fender of the sawtooth damping plate at the bottom of the cylindrical FPSO of the present invention; Fig.10 It is a structural schematic diagram of a temporary winch for undocking a cylindrical FPSO according to the present invention; Fig.11 It is a structural schematic diagram of a tugboat and a dock door of the present invention; Fig.12 It is a structural schematic diagram of the main tugboat and the cylindrical FPSO of the present invention; Fig.13 It is a schematic diagram of the structure of the cylindrical FPSO mooring short cable and the main tugboat cable of the present invention; Fig.14 It is a schematic diagram of the structure of the cylindrical FPSO of the present invention in a harbor with a main tugboat and an auxiliary tugboat.

[0018] Description of the markings in the figure: 1. Cylindrical FPSO; 2. Dock; 3. Cable; 4. Mooring short cable; 5. Cylinder; 6. Mooring eye plate; 7. LUG pipe; 8. Pilot car; 9. Winch; 10. Cable bollard; 11. Sawtooth damping plate; 12. Dock wall; 13. Rubber fender; 14. Colored flag; 15. Submersible pump; 16. Pilot pipe; 17. Process deck; 18. Water bag; 19. Ballast tank; 2 0. Diver; 21. Outer plate; 22. Dock threshold; 23. Dock door; 24. Tugboat; 25. Small boat with cable; 26. Main tugboat; 27. Harbor; 28. Assistant tugboat; 29. ​​Shackle; 30. Slide; 31. Temporary winch; 32. Tow hook; 33. Steel plate; 34. Counterweight; 35. Lifting eye; 36. Round steel; 37. Protruding outer plate; 38. Chain; 39. Guide wheel. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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 those skilled in the art without creative work are within the scope of protection of the present invention.

[0020] Those skilled in the art will appreciate that, although some embodiments herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present invention and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0021] Please refer to the attached Figure 1 To Attachment Fig.14 The undocking method applicable to a cylindrical FPSO of the present invention is described.

[0022] like Figure 1 As shown, the undocking method applicable to a cylindrical FPSO in the present invention comprises the following steps: S1, cable and marking in the dock. According to the rigging arrangement plan of the towing cable 3 of the cylindrical FPSO 1 in the dock 2, the mooring short cable 4 is tied to the mooring eye plate 6 and LUG tube 7 of the cylindrical FPSO 1 shell 5 in advance, and the cable 3 is arranged based on the undocking plan, and connected to the boat guide trolley 8 and winch 9. At the same time, rubber fenders 13 are arranged on both sides of the serrated damping plate 11 at the bottom of the cylindrical FPSO 1 close to the dock wall 12, and several eye-catching colored flags 14 are pulled. The actual position of the outer contour in the water is observed to avoid collision between the cylindrical FPSO 1 and the dock wall 12 when undocking, so as to ensure the safety of undocking; S2, counterweight load adjustment, put the submersible pump 15 into the seawater to a certain depth above the sea level, connect the submersible pump 15 to the water bag 18 at the process deck 17 of the cylindrical FPSO 1 through the water pipe 16, and then connect the water pipe 16 coming out of the water bag 18 to the submersible pump 15 of each ballast tank 19, so as to transport the stored water in the water bag 18 to each ballast tank 19 of the cylindrical FPSO 1, and after filling each ballast tank 19 of the cylindrical FPSO 1 to the designed depth according to the pre-designed ballast draft plan, arrange corresponding divers 20 to check the water tightness of the cabin; S3, float and level, gradually release water to the dock 2 to the draft depth of the cylindrical FPSO 1, and arrange divers 20 to check the water tightness of the outer plate 21 of the cylindrical FPSO 1 cylinder 5, and observe the floating state of the cylindrical FPSO 1 hull; if the hull is not level after floating, fill water to level it, and continue to release water to the dock 2 until the cylindrical FPSO 1 floats to a preset height from the dock pier; S4, guiding the ship in the dock, by cooperating with the guiding trolley 8, winch 9, and mooring bollard 10 to change the turning point and the mooring eye plate 6 and LUG pipe 7 positions outside the cylindrical FPSO 1 cylinder 5, gradually drag the cylindrical FPSO 1 to the designated position in front of the dock threshold 22, and control its state to be stable. The guiding trolley 8 is the main towing force of the cylindrical FPSO 1, and the winch 9 assists in controlling its forward moving direction out of the dock; S5, the dock gate 23 is moored. A short mooring line 4 is hung on the dock gate 23 in advance. After the tugboat 24 is in place, a small boat with a cable 25 is used to connect it to the cable 3 of the tugboat 24. The dock gate 23 is connected to the two tugboats 24 through the cable 3. After the state of the dock gate 23 is controlled to be stable under the action of the tugboat 24, the dock gate 23 is dragged out of the dock threshold 22 to open the dock gate 23. The dock gate 23 is further dragged to the pre-specified position of the wharf by the tugboat 24 for mooring; S6, with the main tugboat 26, after the dock door 23 is opened, the cylindrical FPSO 1 is first controlled in a safe floating posture by cooperating with the trolley 8, the winch 9, and the mooring pile 10 connected to the winch 9, and then the mooring boat 25 is used to connect the tugboat 24 cable 3 of the main tugboat 26 to the mooring short cable 4 outside the cylinder 5 of the cylindrical FPSO 1; S7, the main tugboat 26, the towing hook 32 of the towing trolley 8, the winch 9 and the mooring bollard 10 cooperate with each other to tow the cylindrical FPSO 1 out of the dock 2 to the harbor 27; S8, guide the ship in the harbor 27, connect the cable 3 of the auxiliary tugboat 28 with the mooring short cable 4 of the cylindrical FPSO1 with the cable boat 25 in the harbor 27, based on the main tugboat 26 providing the main towing force for the cylindrical FPSO1 and the auxiliary tugboat 28 providing the towing lateral force, assist in controlling the guiding direction of the cylindrical FPSO1, and the winch 9 assists the cylindrical FPSO1 to prevent rotation, and drag the cylindrical FPSO1 to the designated position in the harbor 27. During the guiding process of the harbor 27, timely untie the cables 3 of the guiding trolley 8 and the winch 9, and finally realize the safe floating posture control of the cylindrical FPSO1 through the main tugboat 26 and the auxiliary tugboat 28 to ensure the safe undocking of the cylindrical FPSO1.

[0023] By guiding the cylindrical FPSO1 to undock, not only the problem that the cylindrical structure is difficult to balance and adjust and easy to rotate during the undocking process is solved, but also the difficulty of observing the distance between the bottom serrated damping plate 11 and the dock wall 12 underwater is effectively overcome. The safety of the cylindrical FPSO1 undocking process is significantly enhanced, and the work efficiency is also greatly improved, so that the cylindrical FPSO1 can be undocked safely and efficiently, improving the overall quality of the undocking operation.

[0024] Further, if Figures 2 to 6As shown, when the mooring short cable 4 is pre-hung outside the cylindrical FPSO1 cylinder 5, the folded end of the mooring short cable 4 is first connected to the mooring eye plate 6 on the cylindrical FPSO1 cylinder 5 through the shackle 29, and the other end is connected to the cable 3 through the shackle 29, and then the cable 3 pre-designed in the undocking plan is connected to the boat guide trolley 8 or winch 9 and the mooring bollard 10 respectively. When the mooring short cable 4 is pre-hung on the cylindrical FPSO1 cylinder 5, the folded end of the mooring short cable 4 is connected to the LUG pipe 7, and the other end is connected to the cable 3 through the shackle 29, and then the cable 3 pre-designed in the undocking plan is connected to the boat guide trolley 8 or winch 9 and the mooring bollard 10;

[0025] Further, such as Figure 3 and Fig.10 As shown, there are four boat-leading trolleys 8, two of which are symmetrically arranged on the slideways 30 on both sides of the dock 2, and six capstans 9, three of which are symmetrically arranged on both sides of the dock 2, and the capstan 9 arranged in the middle is a temporary capstan 31, which can be moved according to the needs of the operation during the undocking process, thereby ensuring the safety of the undocking of the cylindrical FPSO 1; the height of the mooring short cable 4 on the cylindrical FPSO1 cylinder 5 connected by the towing hook 32 of the boat-leading trolley 8 is 12m, and the height of the mooring short cable 4 on the cylindrical FPSO1 cylinder 5 connected by the capstan 9 is 21m.

[0026] Further, if Figures 2 to 12 As shown, a total of 8 cables 3 are pre-designed in the undocking plan. During the undocking process, for the boat guiding trolley 8, 4 cables 3 are connected to the towing hook 32 of the boat guiding trolley 8, and for the winch 9 and the mooring pile 10, the 4 cables 3 are firstly wound around the corresponding mooring pile 10 for several turns, and then 2 cables are connected to the winch 9 and 2 cables are connected to the temporary winch 31; the temporary winch 31 is placed on the steel plate 33 and welded to the steel plate 33; the steel plate 33 is laid on both sides of the dock wall 12, and a counterweight block 34 of designed weight is placed on it to increase the gravity of the steel plate 33.

[0027] Further, if Figures 2 to 9As shown in the figure, the rubber fender 13 is wrapped around the position of the serrated damping plate 11 at the bottom of the cylindrical FPSO 1 near the two sides of the dock wall 12, and four designed lifting ears 35 are welded on the bottom serrated damping plate 11, so the rubber fender 13 is a four-point fixed form; when the rubber fender 13 is fixed to the serrated damping plate 11 at the bottom of the cylindrical FPSO 1, the rubber fender 13 is a hollow cylinder, and a round steel 36 passes through the center hole of the rubber fender 13, and the length of the round steel 36 is greater than The rubber fender 13 is welded with lifting ears 35 on both sides of the round steel 36; the installation position of the rubber fender 13 is exactly located at the center of the protruding outer plate 37 of the bottom serrated damping plate 11, and the size can cover the protruding outer plate 37 of the serrated damping plate 11; one end of the iron chain 38 is connected to the lifting ear 35 of the round steel 36 through the shackle 29, and the other end is connected to the lifting ear 35 on the serrated damping plate 11 through the shackle 29, so as to fix the rubber fender 13 to the serrated damping plate 11; Further, if Figure 7 , Fig.11 and Fig.12 As shown, rubber fenders 13 and guide wheels 39 are installed at certain intervals in the middle of the dock walls 12 on both sides and near the harbor 27. The rubber fenders 13 and guide wheels 39 are made of polymer materials, which can convert the rigid collision between the cylindrical FPSO 1 and the dock wall 12 into an elastic collision, effectively preventing the two from being damaged due to the collision; in addition, when the cylindrical FPSO 1 collides with the dock wall 12, it plays a guiding role, ensuring that the cylindrical FPSO 1 can smoothly move away from the central position of the dock 2 after colliding with the dock wall 12 during the undocking process; Further, if Figure 3 and Fig.14 As shown, when the cylindrical FPSO 1 is ballast-loaded, the submerged pump 15 in each ballast tank 19 needs to be turned off after each half-hour of water filling, and the corresponding diver 20 is arranged to enter the adjacent compartment to observe the water tightness of the filled ballast tank 19, and this cycle is repeated until each compartment is filled with water to the designed water depth for ballast-loaded adjustment; Further, if Figure 4 , Figure 5 , Figure 6 and Fig.14 As shown, when the cylindrical FPSO1 is floated and leveled, the process of releasing water to the dock 2 is carried out in two steps. First, the dock 2 is released to the 4.3m draft of the cylindrical FPSO1 and then the release of water is stopped. Divers 20 are arranged to observe the water tightness of the outer plate 21 of the cylindrical FPSO1. If the requirements are met, the dock 2 is continued to release water to the 7.7m design water depth for the cylindrical FPSO1 to be launched, and the release of water is stopped. Then the water tightness of the outer plate 21 is checked. The floating and leveling state of the cylindrical FPSO1 is judged by the difference in the draft scales arranged at the four corners of the hull, and the judgment criterion is that the height difference of the draft scales arranged at the four corners of the hull is not greater than 300m. Further, if Figure 2 and Figure 3 As shown, the ship is guided in the dock, and the guiding trolley 8 is used as the main dragging force of the cylindrical FPSO 1 and controls its rotation; the winch 9 assists in controlling the forward direction and rotation of the cylindrical FPSO 1 when it is undocking; when the winch 9 and the temporary winch 31 are guided in the dock, the order of the mooring piles 10 connected to the winch 9 and the temporary winch 31 can be adjusted according to the wind direction at the site and in accordance with the principle of first downwind and then upwind; Further, if Figures 2 to 14 As shown, when the dock gate 23 is to be moored, two auxiliary tugboats 28 are used, and the water in the ballast tank 19 of the dock gate 23 needs to be released in advance through the submerged pump 15, and the mooring short line 4 is pre-hung on its lifting lug 35. When the dock gate 23 floats to a certain height, the mooring short line 4 is connected to the cable 3 of the tugboat 24 of the auxiliary tugboat 28 through the cable boat 25, and then the dock gate 23 is towed out of the dock threshold 22 by the two auxiliary tugboats 28 to open the dock gate 23, and then it is towed to the designated position of the dock for mooring.

[0028] Further, if Figures 2 to 6 As shown, when the cable 3 of the main tugboat 26 is connected to the mooring short cable 4 outside the cylindrical FPSO 1 cylinder 5, the mooring short cable 4 needs to be tied to three LUG tubes 7 at the same height outside the cylindrical FPSO 1 cylinder 5; the mooring short cable 4 is connected to the three LUG tubes 7 at the same height outside the cylindrical FPSO 1 cylinder 5, and its specific form is that for the LUG tubes 7 on both sides, the 25m mooring short cable 4 is folded in half and one end is connected to the LUG tube 7, and the other end is connected to the 20m mooring short cable 4 folded in half through the shackle 29. The other end of the folded 20m mooring short line 4 is connected to the shackle 29; for the middle LUG tube 7, one end of the 25m mooring short line 4 is directly connected to the LUG tube 7, and the other end is connected to the shackle 29; the free ends of the mooring short lines 4 connected to the three LUG tubes 7 at the same height outside the cylindrical FPSO 1 cylinder 5 are tied to the same shackle 29, and then the main tugboat 26 is connected to the shackle 29 through the cable boat 25, so as to connect the main tugboat 26 and the cylindrical FPSO 1 together; Further, if Figures 2 to 6 As shown, with the main tugboat 26, it is necessary to use a shackle 29 to tie the mooring short cable 4 into a figure-eight cable form on the mooring eye plate 6 and LUG tube 7 on the cylindrical FPSO 1 shell 5 in advance, and place the shackle 29 at the end of the figure-eight cable on the water surface to facilitate the connection of the cable 3 of the tugboat 24 after the main tugboat 26 is in place.

[0029] Further, if Figure 2 and Fig.14As shown, the main tugboat 26 is used as the main towing force for the cylindrical FPSO1 to leave the dock threshold 22, and the capstan 9 is used to change the steering point to assist in providing the lateral towing force of the cylindrical FPSO1 and control its rotation. When the cylindrical FPSO1 arrives at the harbor 27, the tugboat 24 cables 3 of the two auxiliary tugboats 28 are connected to the mooring short cables 4 pre-hung outside the cylindrical FPSO1 cylinder 5; Further, if Fig.12 and Fig.14 As shown, the harbor guide uses the main tugboat 26 as the main towing force of the cylindrical FPSO 1, and the two auxiliary tugboats 28 provide lateral towing force to assist in controlling the undocking direction of the cylindrical FPSO 1. The winch 9 assists in controlling the rotation of the cylindrical FPSO 1, and it is necessary to pay attention to the need to slowly release the cable to prevent the cylindrical FPSO 1 from rotating significantly.

[0030] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for undocking a cylindrical FPSO, characterized in that: It includes the following steps: S1. Cables and markings in the dock. According to the layout plan of the towing cable rigging of the cylindrical FPSO in the dock, the mooring short cable is tied to the mooring eye plate and LUG tube of the cylindrical FPSO shell in advance, and the cable layout is based on the undocking plan, and it is connected to the boat guide trolley and winch. At the same time, rubber fenders are arranged on both sides of the serrated damping plate at the bottom of the cylindrical FPSO near the dock wall, and several eye-catching colored flags are pulled to observe the actual position of the outer contour in the water; S2. Adjust the load with counterweight, place the submersible pump into the seawater, connect the water pipe to each ballast tank of the cylindrical FPSO, fill the tank with water to the designed depth, and then the diver will check the water tightness of the tank; S3, float and level, gradually release water to the dock to the draft depth of the cylindrical FPSO, check the water tightness of the cylindrical FPSO shell, and observe the floating state of the cylindrical FPSO hull. If the hull is not level after floating, fill it with water to level it, and continue to release water to the dock until the cylindrical FPSO floats to the preset height from the dock; S4. Pilot the ship in the dock, coordinate with the pilot trolley, winch, mooring bollard and the berthing point of the cylindrical FPSO cylinder system, and drag the cylindrical FPSO to the designated position in front of the dock threshold; S5, the dock gate is started to moor, the dock gate is connected to the two tugboats through cables, and the dock gate is towed to the designated location of the wharf for mooring; S6, with the main tugboat, connect the mooring short cable of the FPSO with the main tugboat cable, and use the trolley and winch to control the floating posture of the cylindrical FPSO; S7, the main tugboat, the tugboat towing hook, the winch and the mooring bollard cooperate with each other to tow the cylindrical FPSO out of the dock to the harbor; S8, piloting in the harbor, using a small boat with a cable to connect the auxiliary tugboat cable with the short mooring cable of the cylindrical FPSO in the harbor, based on the main towing force provided by the main tugboat and the lateral towing force provided by the auxiliary tugboat, assist in controlling the undocking direction of the cylindrical FPSO, the winch assists the rotation of the cylindrical FPSO, and the pilot trolley hook and winch cable are unhooked in time to ensure the safe undocking of the cylindrical FPSO.

2. The method for undocking a cylindrical FPSO according to claim 1, characterized in that: When adjusting the counterweight of a cylindrical FPSO, water discharge must be stopped every time the water in the cabin reaches a certain depth, and divers are arranged to enter each cabin to observe the watertightness of the cabin. This cycle is repeated until the cabin is filled with water to the designed water depth.

3. The method for undocking a cylindrical FPSO according to claim 1, characterized in that: To start mooring at the dock gate, a short mooring line must be pre-hung on the lifting lug 35 of the dock gate in advance. When the tugboat is in place, the tugboat towing cable of the tugboat is connected to the short mooring line of the dock gate to realize the operation of starting mooring at the dock gate.

4. The undocking method applicable to a cylindrical FPSO according to claim 1, characterized in that: With a main tugboat, it is necessary to use shackles to tie the mooring short cable into a figure-eight cable on the mooring eye plate and LUG tube on the cylindrical FPSO shell in advance, and place the shackle at the end of the figure-eight cable on the water surface to facilitate the connection of the tugboat cable after the main tugboat is in place.

5. The undocking method applicable to a cylindrical FPSO according to claim 1, characterized in that: The towing trolley is used as the main towing force for the cylindrical FPSO in the dock, and the winch assists in controlling its forward movement direction out of the dock.

6. The undocking method applicable to a cylindrical FPSO according to claim 1, characterized in that: To guide the ship out of the dock, the main tugboat is the main towing force of the cylindrical FPSO, the towing hook of the guiding trolley is the main control of the rotation, and the winch is the auxiliary control of the rotation of the cylindrical FPSO.

7. The undocking method applicable to a cylindrical FPSO according to any one of claims 1 to 6, characterized in that: There are 4 boat-guiding trolleys, 2 of which are symmetrically arranged on both sides of the dock; there are 6 winches, 3 of which are symmetrically arranged on both sides of the dock, and the winch arranged in the middle is a temporary winch.

8. The undocking method applicable to a cylindrical FPSO according to any one of claims 1 to 6, characterized in that: The height of the mooring short cable on the cylindrical FPSO cylinder connected by the trolley towing hook is 12m, and the height of the mooring short cable on the cylindrical FPSO cylinder connected by the winch is 21m.

9. The undocking method applicable to a cylindrical FPSO according to any one of claims 1 to 6, characterized in that: The rubber fender installed at the position of the serrated damping plate at the bottom of the cylindrical FPSO is cylindrical and is fixed to the serrated damping plate at four points.

10. The undocking method applicable to a cylindrical FPSO according to any one of claims 1 to 6, characterized in that: The leveling of cylindrical FPSO is to ensure that the draft difference at the four corners of the hull is no more than 300mm.

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