An integrated jacket structure and installation method for an offshore converter station

Abstract

The present invention provides an integrated jacket structure for an offshore converter station. The upper portion of the integrated jacket is connected to the upper assembly of the offshore converter station, and steel pipe piles are used to anchor the integrated jacket. The integrated jacket includes a main butt joint conduit that supports the upper assembly, and an external frame disposed on the periphery. A connecting frame is disposed in the lower region of the integrated jacket to simultaneously connect the main butt joint conduit and the external frame. The inner and outer sides of the integrated jacket are respectively provided with external and internal casings connected to the steel pipe piles. To address the problems of the increased weight of the jacket foundation of an offshore converter station, which makes it difficult to hoist it, and the limited sliding and launching in shallow waters, the present invention utilizes internal and external casing structures with different top elevations to optimize the load transmission path of the integrated jacket foundation of the offshore converter station, thereby improving the structural bearing capacity of the integrated jacket.

Description

Technical Field

[0001] The present invention relates to the field of marine engineering technology, and in particular to an integral jacket structure for an offshore converter station and an installation method thereof. Background Art

[0002] Traditional monolithic jacket structures for offshore converter stations require a central channel for floating access, so the sections near and above the water surface are often designed with either double-row or single-row connections. For example, the double-row jacket structure disclosed in Patent Document [CN209178966U], a monolithic jacket structure for large offshore platforms installed by floatation in deepwaters, offers high rigidity and stability, but the jacket structure is complex and requires a large amount of steel. Another example is the single-row jacket structure disclosed in Patent Document [CN217307269U], a closed, compact offshore converter station. While this reduces steel consumption, the piles are misaligned, resulting in poor load transfer. Furthermore, the piles are located in the middle of the jacket, resulting in an excessively large crane boom, making pile lifting difficult. Furthermore, after the jacket structure is lowered, there is a significant period of time before the piles are secured. If the seabed is in soft soil, such as silt, the unsecured jacket may sink or slip under wave forces.

[0003] Furthermore, traditional installation methods for integrated jacket structures on offshore platforms can be categorized as hoisting or skidding. Hoisting is generally used when the jacket weighs less than 8,000 tons and can be lifted by a crane vessel. Skidding is generally used when the jacket weighs more than 8,000 tons and cannot be lifted by a crane vessel. Regarding the integrated jacket foundation for offshore converter stations, the large size and weight of the upper components of these stations also contribute to the large size and weight of the jacket foundation. Therefore, the integrated jacket foundation for offshore converter stations generally weighs over 8,000 tons, making it impossible to install it by crane vessel with existing equipment. However, the water depth at the installation site of offshore converter stations is often not very deep, and skidding the jacket into the water could result in it hitting the seabed. Therefore, the traditional skidding method is not suitable for water depths less than 60 meters. Summary of the Invention

[0004] The first objective of the present invention is to provide an integrated jacket structure that optimizes the force transmission path of the jacket foundation and addresses the issues of heavy weight, which hinders hoisting, and shallow waters, which hinder sliding launching. To this end, the present invention employs the following technical solutions:

[0005] The jacking frame is connected to the upper assembly of the offshore converter station and is provided with steel pipe piles for anchoring the jacking frame. The jacking frame includes a docking main conduit for supporting the upper assembly and an external frame arranged on the periphery. The lower area of ​​the jacking frame is provided with a connecting frame for connecting the docking main conduit and the external frame. The inner and outer sides of the jacking frame are respectively provided with an external casing and an internal casing connected to the steel pipe piles. The top elevation of the external casing connected to the external frame is higher than the top elevation of the internal casing connected to the docking main conduit, so as to form a rapid transmission path for the load of the upper assembly. The bottom of the jacking frame is connected to a separating buoyancy box, so that the separating buoyancy box can form a water-filled and settled state or a seated and anti-sinking state for the jacking frame.

[0006] Furthermore: the external frame is connected to the periphery of the docking main conduits on both sides, the connecting frame is set in the middle area of ​​the integral jacket, and a slot for floating ships to enter and exit is reserved above the connecting frame to form an offshore mobile channel.

[0007] Furthermore, a diagonal brace is provided between the outer frame, which is away from the central side pipe pile of the integral jacket and the butted main pipe.

[0008] Furthermore: the separated buoyancy box is connected and arranged in the frame structure of the external frame.

[0009] Furthermore: a plurality of the partition pontoons are independently provided within the external frame structure, and the partition pontoons in each area are equipped with a water injection pipe for independent use.

[0010] Furthermore: the top elevation of the inner sleeve is lower than the top elevation of the connecting frame.

[0011] Furthermore: a pile leg coupling device is connected between the upper assembly block and the docking main conduit.

[0012] Furthermore: a guide flaring section is provided at the top of the outer sleeve and the inner sleeve.

[0013] The second object of the present invention is to provide an installation method that can solve the difficulties in underwater installation of an integral jacket structure. To this end, the present invention adopts the following technical solutions:

[0014] A method for installing an integral jacket structure for an offshore converter station, comprising the following specific steps:

[0015] S1: prefabricate the integral jacket and the steel pipe piles on land, and transport the integral jacket to a designated sea area by a semi-submersible barge;

[0016] S2: After arriving at the designated sea area, the semi-submersible barge sinks to immerse the integral jacket in water, and the integral jacket is self-balanced by the empty partition buoyancy tank;

[0017] S3: the semi-submersible barge continues to sink so as to leave the area of ​​the integral jacket, and slowly injects ballast water into the partition buoyancy tanks of each area so as to make the bottom of the integral jacket sink to the seabed mud surface;

[0018] S4: First, construct the steel pipe piles outside the slot to achieve a fixed connection between the integrated jacket and the seabed, and after the external casing is grouting, construct the steel pipe piles inside the slot to complete the offshore installation of the integrated jacket;

[0019] S5: Installing the leg coupling device on the docking main conduit at the connection with the upper assembly, and completing the installation of the upper assembly of the offshore converter station by using a floating and dragging method.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This invention addresses the problems of increased weight and difficulty in hoisting the jacket foundation of an offshore converter station, as well as limited sliding launch in shallow waters. By employing internal and external casing structures with different top elevations, this design optimizes the load transmission path of the jacket foundation, thereby increasing the overall jacket's structural bearing capacity. Furthermore, through the self-floating installation of the jacket using a separate pontoon, large jackets weighing over 8,000 tons can be installed without hoisting or launching, even in shallow water. Furthermore, after being filled with water, the separate pontoon serves as an anti-sinking structure for the jacket, further ensuring its stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a front structural schematic diagram of the overall structure of the present invention in a state of being in place at sea;

[0023] Figure 2 It is a side structural schematic diagram of the overall structure of the present invention in the offshore position state;

[0024] Figure 3 This is a schematic diagram of the planar structure of the partition pontoon of the present invention;

[0025] Figure 4 A schematic diagram of the marine transportation of the integrated jacket of the present invention;

[0026] Figure 5 A schematic diagram of the detachment of the integral jacket during offshore transportation according to the present invention;

[0027] Figure 6A schematic diagram of the integrated jacket of the present invention in a subsidence state at sea;

[0028] Figure 7 This is a schematic diagram of the offshore installation of the integrated jacket of the present invention.

[0029] The markings in the accompanying drawings are: upper assembly block 1, pile leg coupling device 2, integral jacket 3, docking main conduit 31, external frame 32, external casing 33, internal casing 34, connecting frame 35, steel pipe pile 4, partition pontoon 5, first pontoon 51, second pontoon 52, third pontoon 53, water injection pipe 54, semi-submersible barge 6. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the accompanying drawings and examples, but they are not intended to limit the present invention.

[0031] like Figure 1-7 As shown, an integrated jacket structure for an offshore converter station is provided. The integrated jacket structure for an offshore converter station includes an upper portion of the integrated jacket 3 connected to an upper assembly 1 of the offshore converter station, and steel pipe piles 4 for anchoring the integrated jacket 3. The integrated jacket 3 includes a main docking conduit 31 supporting the upper assembly 1 and an outer frame 32 arranged on the periphery. A connecting frame 35 is provided in the lower region of the integrated jacket 3 for connecting the main docking conduit 31 and the outer frame 32. An outer casing 33 and an inner casing 34 connected to the steel pipe piles 4 are provided on the inner and outer sides of the integrated jacket 3, respectively. The top elevation of the outer casing 33 connected to the outer frame 32 is higher than the top elevation of the inner casing 34 connected to the main docking conduit 31, thereby forming a rapid load transfer path for the upper assembly 1. A partition pontoon 5 is provided at the bottom of the integrated jacket 3, so that the partition pontoon 5 can form a water-filled and submerged state or a seated and anti-sinking state for the integrated jacket 3.

[0032] like Figure 1-3 As shown, specifically, the outer frame 32 is connected to the periphery of the docking main conduits 31 on both sides, the connecting frame 35 is set in the middle area of ​​the integral jacket 3, and a slot for the entry and exit of floating vessels is reserved above the connecting frame 35, which can facilitate floating installation and form an offshore mobile channel.

[0033] In this embodiment, the integral jacket frame 3 is divided into three parts: external frames 32 distributed on both sides and a connecting frame 35 in the middle; and the docking main conduits 31 distributed on the sides of the middle area are connected through the connecting frame 35 in the middle to form the integral jacket frame 3 as a whole.

[0034] like Figure 1 and 3Specifically, as shown, diagonal braces are provided between the outer frame 32's centrally located piles and the docking main conduit 31. This creates a trapezoidal cross-section of the outer frame 32. The piles, located on the short sides of the outer frame 32, located away from the center of the integral jacket 3, can serve as external sleeves 33, with their top elevations near the water surface. In this embodiment, the outer frame 32 also preferably has a trapezoidal cross-section in the transverse direction. It should be noted that the external sleeves 33 are located at the outer frame endpoints of the trapezoidal outer frame 32, and the inner frame of the trapezoidal outer frame 32 can serve as docking main conduits 31. Preferably, three docking main conduits 31 are provided.

[0035] like Figure 3 As shown, specifically, by configuring the external and internal casings 33 and 34 at different top elevations, the load of the upper assembly 1 can be quickly transferred to the steel pipe piles 4 outside the slot, shortening the path for load transfer to the steel pipe piles 4. Multiple, preferably two, internal casings 34 are provided on each docking main conduit 31. Because the internal casings 34 inside the slot connect to a sufficient number of steel pipe piles 4, the bearing capacity requirements under different geological conditions are met, while also improving the bearing capacity of the monolithic jacket 3 and minimizing component deformation.

[0036] Among them, since the steel pipe piles 4 on the outside of the notch are easy to insert and the number is small, these four steel pipe piles 4 can be inserted and fixed before the main piles, which can shorten the time from the placement of the integral jacket 3 to the insertion and fixing of the piles, and avoid the settlement, deformation and slippage of the unfixed integral jacket 3. After being fixed, the steel pipe piles 4 can also be used as engineering piles to stabilize the integral jacket 3 when it is in place.

[0037] like Figure 1-3 As shown, specifically, the partition pontoon 5 is connected and arranged in the frame structure of the external frame 32.

[0038] like Figure 3 As shown, a plurality of partition pontoons 5 are independently provided within the frame structure of the external frame 32 , and the partition pontoons 5 in each area are equipped with a water injection pipe 54 for independent use.

[0039] In this embodiment, the partitioned pontoons 5 on the same side include a first pontoon 51, a second pontoon 52, and a third pontoon 53. Water injection pipes 54 are provided at the tops of the first, second, and third pontoons 51, 52, and 53. By adjusting the amount of water injected into each pontoon, the sinking posture of the entire monolithic jacket 3 can be adjusted and corrected, ensuring a stable and level position during the placement of the monolithic jacket 3. This allows the installation of a large monolithic jacket 3 weighing over 8,000 tons to be completed without the need for hoisting or sliding into the water, even in shallow water.

[0040] At the same time, a partition pontoon 5 is provided at the bottom of the integral jacket 3. Due to the large rigidity and area of ​​the partition pontoon 5, after the partition pontoon 5 is filled with water, close contact is formed between the bottom of the partition pontoon 5 and the seabed surface, thereby preventing the integral jacket 3 from excessive settlement and deformation.

[0041] The top elevation of the inner casing 34 is lower than the top elevation of the connecting frame 35. This can further ensure that the steel pipe pile 4 is installed smoothly.

[0042] Wherein, guide expansion sections are provided at the top of the outer casing 33 and the inner casing 34 so that the steel pipe pile 4 can be more easily installed and anchored underwater.

[0043] Specifically, a leg coupling device 2 is provided between the upper assembly block 1 and the docking main conduit 31 .

[0044] See also Figure 1-7 When the integrated jacket 3 of the offshore converter station is installed as a whole at sea so as to be connected to the upper assembly 1, the specific steps are as follows:

[0045] S1: prefabricate the integral jacket 3 and steel pipe piles 4 on land, and transport the integral jacket 3 to a designated sea area via a semi-submersible barge 6;

[0046] S2: After arriving at the designated sea area, the semi-submersible barge 6 sinks, so that the integral jacket 3 is immersed in the water, and the integral jacket 3 is balanced in the water by the empty partition pontoon 5;

[0047] S3: After ensuring the integral jacket 3 is balanced, the semi-submersible barge 6 continues to sink to leave the area of ​​the integral jacket 3 and slowly injects ballast water into the partition pontoons 5 of each area. During the sinking stage, the flow rate and volume of the ballast water in the first pontoon 51, the second pontoon 52, and the third pontoon 53 are controlled to ensure a stable posture during the sinking process. The ballast water is fully injected until the bottom of the integral jacket 3 sinks to the seabed mud surface.

[0048] S4: First, the steel pipe piles 4 of the external casing 33 outside the slot are constructed and driven to securely connect the integrated jacket 3 to the seabed. Subsequently, after the external casing 33 is grouted, the steel pipe piles 4 of the internal casing 34 inside the slot are constructed, thereby completing the offshore installation of the integrated jacket 3.

[0049] S5: Install the leg coupling device 2 on the docking main conduit 31 at the connection with the upper assembly 1, and complete the installation of the upper assembly 1 of the offshore converter station by using the floating and dragging method.

[0050] The above embodiment is only a preferred technical solution of the present invention. Those skilled in the art should understand that the technical solutions or parameters in the embodiment can be modified or replaced without departing from the principle and essence of the present invention, and all should be covered by the protection scope of the present invention.

Claims

1. An integrated jacket structure for an offshore converter station, wherein the upper portion of the integrated jacket (3) is connected to an upper assembly block (1) of the offshore converter station, and a steel pipe pile (4) is provided for anchoring the integrated jacket (3), characterized in that: The integral jacket (3) comprises a main butt joint pipe (31) supporting the upper assembly block (1) and an external frame (32) arranged on the periphery, and a connecting frame (35) is provided in the lower region of the integral jacket (3) for connecting the main butt joint pipe (31) and the external frame (32) at the same time; An outer casing (33) and an inner casing (34) connected to the steel pipe pile (4) are respectively provided on the inner and outer sides of the integral jacket (3), and the top elevation of the outer casing (33) connected to the outer frame (32) is higher than the top elevation of the inner casing (34) connected to the docking main pipe (31), so as to form a rapid transfer path for the load of the upper assembly (1); A separation buoyancy box (5) is connected to the bottom of the integral jacket (3), so that the separation buoyancy box (5) forms a water-filled and settled state or a seated and anti-sinking state for the integral jacket (3); The partition buoyancy box (5) is connected and arranged in the frame structure of the external frame (32); The top elevation of the inner sleeve (34) is lower than the top elevation of the connecting frame (35).

2. The integrated jacket structure for an offshore converter station according to claim 1, characterized in that: The outer frame (32) is connected to the periphery of the docking main conduits (31) on both sides, the connecting frame (35) is arranged in the middle area of ​​the integral jacket (3), and a slot for floating ships to enter and exit is reserved above the connecting frame (35) to form an offshore mobile channel.

3. The integrated jacket structure for an offshore converter station according to claim 1, characterized in that: The external frame (32) is connected to the central side pipe pile of the integral jacket (3) and is provided with a diagonal brace to connect with the docking main pipe (31).

4. The integrated jacket structure for an offshore converter station according to claim 1, characterized in that: A plurality of the partition pontoons (5) are independently provided within the frame structure of the external frame (32), and the partition pontoons (5) in each area are equipped with a water injection pipe (54) for independent use.

5. The integrated jacket structure for an offshore converter station according to claim 1, characterized in that: A pile leg coupling device (2) is connected between the upper assembly block (1) and the docking main conduit (31).

6. The integrated jacket structure for an offshore converter station according to claim 1, characterized in that: A guide flaring section is provided at the top of the outer sleeve (33) and the inner sleeve (34).

7. A method for installing an integral jacket structure for an offshore converter station, characterized in that: The specific steps of performing offshore installation using the integrated jacket structure for an offshore converter station according to any one of claims 1 to 6 are as follows: S1: prefabricate the integral jacket (3) and the steel pipe piles (4) on land, and transport the integral jacket (3) to a designated sea area via a semi-submersible barge (6); S2: After arriving at the designated sea area, the semi-submersible barge (6) sinks, so that the integral jacket (3) is immersed in water, and the self-balancing of the integral jacket (3) is achieved through the empty partition buoyancy box (5); S3: The semi-submersible barge (6) continues to sink so as to leave the area of ​​the integral jacket (3), and slowly injects ballast water into the partition buoyancy boxes (5) of each area so as to make the bottom of the integral jacket (3) sink to the mud surface of the seabed; S4: First, the steel pipe piles (4) outside the notch are constructed to achieve a fixed connection between the integral jacket (3) and the seabed, and after the grouting of the external casing (33) is completed, the steel pipe piles (4) inside the notch are constructed to complete the offshore installation of the integral jacket (3); S5: Install the pile leg coupling device (2) on the docking main conduit (31) at the connection with the upper assembly block (1), and complete the installation of the upper assembly block (1) of the offshore converter station by using a floating drag method.

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