Design method for damping plate of cylindrical FPSO and design method for cylindrical FPSO

Abstract

The invention provides a design method of a damping plate of a cylindrical FPSO (floating production storage and offloading) and the design method of the cylindrical FPSO, which comprises the step of reducing the area of a local position of the damping plate, so that the length of the damping plate in a certain direction is smaller than the width of a dock. Determining that the area reduction position needs to meet the following requirements: avoiding the direction with the worst environmental condition; the area reduction positions are symmetrically arranged, and the symmetric line passes through the center of the damping plate and is parallel or perpendicular to the boundary of the upper module; when symmetry cannot be guaranteed, for the cylindrical FPSO with abundant upper module arrangement space, the length direction of the upper module is perpendicular to the living building, and area reduction positions are selected to be on one side or two sides perpendicular to the living building direction; for the upper module with limited arrangement space, the length direction of the upper module is parallel to the living building, and the area reduction position is selected at one side or two sides parallel to the living building direction. The movement performance of the cylindrical FPSO under the severe sea condition is guaranteed, meanwhile, the hull can be built in a limited dock, and the gantry crane is fully utilized to integrate the upper module.

Description

Technical Field

[0001] This invention relates to the field of oil and gas extraction equipment technology, and in particular to a design method for a damping plate of a cylindrical FPSO and a design method for a cylindrical FPSO. Background Technology

[0002] Floating Production Storage and Offloading (FPSO) units are core equipment in offshore oil and gas development. Traditional FPSOs are mostly slender hull structures similar to ships, and existing shipyards are mostly designed for building this type of FPSO, which is often a slender structure with limited width but long length.

[0003] Currently, cylindrical FPSOs are increasingly favored in deep-water and harsh sea state oilfield development due to their excellent maneuverability, flexible steering, compact layout, and strong resistance to wind and waves. The diameter of a cylindrical FPSO is typically smaller than the total length of a hull-type FPSO, but its diameter is much larger than the width of a hull-type FPSO, and also far exceeds the width of existing slender docks. This creates an irreconcilable contradiction between the enormous diameter of a cylindrical FPSO and the limited width of existing docks during its construction. Summary of the Invention

[0004] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention provides a design method for a damping plate of a cylindrical FPSO and a design method for a cylindrical FPSO, aiming to solve the problem in related technologies where the diameter of the cylindrical FPSO is larger than the width of the dock, making it impossible to construct.

[0005] This invention provides a design method for a damping plate of a cylindrical FPSO, wherein the outer diameter of the damping plate is greater than or equal to the width of the dock. The design method includes reducing the area of ​​a local location of the damping plate based on the width of the dock, such that the length of the damping plate in one direction is less than the width of the dock. Determining the location where the area of ​​the damping plate to be reduced needs to satisfy the following conditions: Based on the actual orientation of the cylindrical FPSO in the operating sea area and the directionality of the environmental conditions, the location where the damping plate needs to reduce its area should avoid being close to the location corresponding to the direction of the most severe and most frequent severe environmental conditions. Based on the mooring cable layout requirements, the orientation of each near-rectangular upper module, and the relative position of the upper module to the dock, when the rectangular boundary is parallel or perpendicular to the width direction of the dock, the position where the damping plate area decreases is symmetrical about a line parallel to the rectangular boundary and passing through the center of the damping plate. When it is not possible to guarantee that the position where the damping plate area decreases is symmetrical about a line parallel to the rectangular boundary and passing through the center of the damping plate, consider one of the following two methods: For the cylindrical FPSO with ample space for the upper module arrangement, the length direction of each upper module is perpendicular to the long side of the living room building, and the position of the damping plate to reduce the area is selected on one or both sides of the line perpendicular to the long side of the living room building. For the cylindrical FPSO with limited space for the upper module arrangement, the length direction of each upper module is parallel to the long side of the living room building, and the position of the damping plate to reduce the area is selected on one or both sides of the line parallel to the long side of the living room building.

[0006] According to the design method of the damping plate of the cylindrical FPSO provided by the present invention, when considering the arrangement orientation of the upper module and its relative position with the dock, the weight of the upper module and the lifting capacity of the gantry crane are also considered. When the weight of a certain upper module exceeds the lifting capacity of a single gantry crane and the conditions for lifting by two gantry cranes are met, the length direction of the upper module needs to be arranged along the length direction of the dock.

[0007] This invention also provides a design method for a cylindrical FPSO, comprising: The damping plate is designed using the damping plate design method for cylindrical FPSOs described above; Based on the shape and size of the damping plate and the width of the dock, determine the out-of-dock structure protection measures corresponding to the structure of the damping plate; Determine the design draft of the cylindrical FPSO; Determine the capacity of the ballast tank and cargo oil tank of the cylindrical FPSO; Accurately evaluate the motion performance of the cylindrical FPSO; Determine the height of the wave-breaking wall of the cylindrical FPSO.

[0008] According to the design method of the cylindrical FPSO provided by the present invention, the method for determining the undocking structure protection measures corresponding to the damping plate structure based on the shape and size of the damping plate and the width of the dock includes determining the diameter of the rubber fender and the gap between the outer side of the rubber fender and the dock wall after the damping plate is installed on the rubber fender.

[0009] According to the design method of the cylindrical FPSO provided by the present invention, wherein the diameter-to-depth ratio (B / D) of the cylindrical FPSO is greater than 2, and the method for determining the design draft of the cylindrical FPSO includes: Determine the maximum draft: Under the premise of meeting the oil storage requirements, the allowable center of gravity height for stability is increased by reducing the draft. When the oil storage tank capacity is insufficient, the maximum draft is calculated by back-calculating the center of gravity height based on an absolutely conservative one. Determine the minimum draft: Under storm conditions, the minimum draft is determined by assessing whether the damping plate leaks water, wherein the minimum draft is the minimum value that ensures the damping plate does not leak water.

[0010] According to the design method of the cylindrical FPSO provided by the present invention, when determining the maximum draft, the hull compartments are not fully determined, and the free surface correction is not accurately considered.

[0011] According to the design method of the cylindrical FPSO provided by the present invention, the method for determining the minimum draft by evaluating whether the damping plate is leaking water includes: Obtain the design draft d, the roll or pitch angle θ of the damping plate under storm conditions, the heave amplitude a, the thickness m of the damping plate, and the diameter φ of the damping plate, and calculate the limiting tilt angle. ; When θ is less than θ lim Then, reduce the design draft by one step and repeat the above steps until θ is greater than θ. lim The calculation is stopped when the design draft d is determined to be the minimum draft at this time.

[0012] According to the design method for a cylindrical FPSO provided by the present invention, determining the tank capacity of the ballast tank and cargo oil tank includes the following steps: Determine the minimum capacity of the ballast tank, which is greater than the capacity required for the cylindrical FPSO to reach the predetermined ballast draft. While meeting the minimum capacity requirements of the ballast tank, the cross-section of the cargo oil tank is designed as a regular octagon, and its circumscribed circle radius is maximized.

[0013] According to the design method of the cylindrical FPSO provided by the present invention, the method for accurately evaluating the motion performance of the cylindrical FPSO includes: When conducting stability assessments, the contributions of all non-watertight bulkheads are ignored; When providing stability height (GM) values ​​for motion performance calculations, the actual contribution of non-watertight bulkheads to reducing fluid sloshing within the compartment is taken into account.

[0014] According to the design method of the cylindrical FPSO provided by the present invention, the method for determining the height of the wave-breaking wall of the cylindrical FPSO includes: The wave-climbing principle is determined, which means that the deck is allowed to climb waves under environmental conditions that occur once every 100 years, but the process deck is not allowed to climb waves under operating conditions that occur once every year. While adhering to the aforementioned wave-breaking principle, the height of the wave-breaking wall should be reduced as much as possible.

[0015] The present invention has the following advantages due to the adoption of the above technical solutions: The present invention provides a damping plate design method for a cylindrical FPSO, which is designed for scenarios where the outer diameter of the damping plate is greater than or equal to the width of the dock. The design method includes reducing the area of ​​a local position of the damping plate based on the width of the dock, so that the length of the damping plate in one direction is less than the width of the dock. The location for reducing the area of ​​the damping plate must meet the following conditions: Based on the actual orientation of the cylindrical FPSO in the operating area and the directionality of environmental conditions, the location for reducing the area of ​​the damping plate should avoid the location corresponding to the direction of the most severe and most frequently occurring severe environmental conditions; Based on the mooring cable layout requirements, the layout orientation of each near-rectangular upper module, and the relative position of the upper module and the dock, when the rectangular boundary is parallel or perpendicular to the width direction of the dock, the location for reducing the area of ​​the damping plate should be symmetrical about a line parallel to the rectangular boundary and passing through the center of the damping plate. When it is not possible to ensure that the rectangular boundary is parallel or perpendicular to the width direction of the dock, consider one of the following two methods: For cylindrical FPSOs with ample space for upper module layout, make the length direction of each upper module perpendicular to the long side of the living quarters, and select the location for reducing the area of ​​the damping plate on one or both sides of the line perpendicular to the long side of the living quarters; For cylindrical FPSOs with limited space for upper module layout, make the length direction of each upper module parallel to the long side of the living quarters, and select the location for reducing the area of ​​the damping plate on one or both sides of the line parallel to the long side of the living quarters. The damping plate design method for cylindrical FPSO provided by this invention can ensure the motion performance of cylindrical FPSO in harsh sea conditions, while enabling the hull to be built in a limited dry dock and making full use of gantry cranes to integrate the superstructure modules. This comprehensively ensures the performance of cylindrical FPSO, guarantees the construction period, and saves costs.

[0016] Furthermore, the design method for a cylindrical FPSO provided by the present invention has the same advantages as described above because it includes the design method for the damping plate of the cylindrical FPSO as described above. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a front view of a cylindrical FPSO provided in an embodiment of the present invention; Figure 2 This is a top view of a cylindrical FPSO in actual orientation according to an embodiment of the present invention; Figure 3 This is a top view of a cylindrical FPSO provided in an embodiment of the present invention, in which the position of the damping plate area is reduced in actual orientation and located on one side of a line perpendicular to the long side of the residential building. Figure 4 This is a schematic diagram of a cylindrical FPSO arranged in a dock, with the damping plate area reduced on one side of a line perpendicular to the long side of the living quarters, according to an embodiment of the present invention. Figure 5 This is a top view of a cylindrical FPSO provided in an embodiment of the present invention, in which the position of the damping plate area is reduced in actual orientation and located on both sides of a line parallel to the long side of the residential building. Figure 6 This is a schematic diagram of a cylindrical FPSO arranged in a dock, with the damping plate area reduced on both sides of a line parallel to the long side of the living quarters, according to an embodiment of the present invention. Figure 7 This is a diagram illustrating the influence of maximum draft on the recovery torque curve characteristic according to an embodiment of the present invention; Figure 8 This is a diagram illustrating the influence of different center of gravity heights on the characteristics of the restoring torque curve, provided by an embodiment of the present invention. Figure 9 This is a diagram illustrating the influence of free surface correction on the characteristics of the restoring torque curve according to an embodiment of the present invention. Figure 10 This is an elevation cross-sectional view of a typical liquid tank with non-watertight bulkheads provided in an embodiment of the present invention.

[0019] Figure label: 100: Damping plate; 200: Wave barrier; 300: Upper module; 400: Gantry crane. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0021] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0023] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0024] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0025] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0026] The present invention provides a damping plate design method for a cylindrical FPSO, which is designed for scenarios where the outer diameter of the damping plate is greater than or equal to the width of the dock. The design method includes reducing the area of ​​a local position of the damping plate based on the width of the dock, so that the length of the damping plate in one direction is less than the width of the dock. The location for reducing the area of ​​the damping plate must meet the following conditions: Based on the actual orientation of the cylindrical FPSO in the operating area and the directionality of environmental conditions, the location for reducing the area of ​​the damping plate should avoid the location corresponding to the direction of the most severe and most frequently occurring severe environmental conditions; Based on the mooring cable layout requirements, the layout orientation of each near-rectangular upper module, and the relative position of the upper module and the dock, when the rectangular boundary is parallel or perpendicular to the width direction of the dock, the location for reducing the area of ​​the damping plate should be symmetrical about a line parallel to the rectangular boundary and passing through the center of the damping plate. When it is not possible to ensure that the rectangular boundary is parallel or perpendicular to the width direction of the dock, consider one of the following two methods: For cylindrical FPSOs with ample space for upper module layout, make the length direction of each upper module perpendicular to the long side of the living quarters, and select the location for reducing the area of ​​the damping plate on one or both sides of the line perpendicular to the long side of the living quarters; For cylindrical FPSOs with limited space for upper module layout, make the length direction of each upper module parallel to the long side of the living quarters, and select the location for reducing the area of ​​the damping plate on one or both sides of the line parallel to the long side of the living quarters. The damping plate design method for cylindrical FPSO provided by this invention can ensure the motion performance of cylindrical FPSO in harsh sea conditions, while enabling the hull to be built in a limited dry dock and making full use of gantry cranes to integrate the superstructure modules. This comprehensively ensures the performance of cylindrical FPSO, guarantees the construction period, and saves costs.

[0027] The following is combined Figures 1-10 The present invention describes the design method of the damping plate of the cylindrical FPSO and the design method of the cylindrical FPSO.

[0028] This invention provides a design method for a damping plate of a cylindrical FPSO, primarily addressing scenarios where the outer diameter of the damping plate 100 is greater than or equal to the width of the dock. The design method involves reducing the area of ​​a local location of the damping plate 100 based on the width of the dock, such that the length of the damping plate 100 in one direction is less than the width of the dock. Determining the location where the area of ​​the damping plate 100 to be reduced needs to satisfy the following conditions: Based on the actual orientation of the cylindrical FPSO in the operating sea area and the directionality of the environmental conditions, the location where the area of ​​the damping plate 100 needs to be reduced should avoid being close to the location corresponding to the direction of the most severe and most frequent severe environmental conditions. Based on the mooring cable layout requirements, the orientation of each near-rectangular upper module 300, and the relative position of the upper module 300 to the dock, when the rectangular boundary is parallel or perpendicular to the width direction of the dock, the position where the area of ​​the damping plate 100 decreases is symmetrical about a line parallel to the rectangular boundary and passing through the center of the damping plate 100. When it is not possible to guarantee that the position where the area of ​​the damping plate 100 decreases is symmetrical about a line parallel to the rectangular boundary and passing through the center of the damping plate 100, consider one of the following two methods: For the upper module 300, a cylindrical FPSO with ample space is arranged so that the length direction of each upper module 300 is perpendicular to the long side of the living room building. The damping plate 100 is positioned on one or both sides of the line perpendicular to the long side of the living room building to reduce its area. For the cylindrical FPSO with limited space for the upper module 300, the length direction of each upper module 300 is parallel to the long side of the living room building, and the position of the damping plate 100 to reduce the area is selected on one or both sides of the line parallel to the long side of the living room building.

[0029] Specifically, when determining the location where the area of ​​the damping plate 100 needs to be reduced, it is necessary to take into account the actual orientation of the cylindrical FPSO in the operating sea area and the directionality of the environmental conditions. Priority should be given to ensuring the area of ​​the damping plate 100 in the direction of the most severe and most frequent severe environmental conditions, so as to ensure the damping performance in the most critical direction.

[0030] When determining the location where the area of ​​the damping plate 100 needs to be reduced, if the damping plate 100 is not in the same direction due to the mooring cable arrangement requirements, priority should be given to symmetry about a certain direction to ensure the symmetry of the cylindrical FPSO performance.

[0031] When determining the location of the damping plate 100 to reduce its area according to the aforementioned method of symmetry in a certain direction, the arrangement orientation of each near-rectangular upper module 300 and its relative position to the dock direction should also be considered. This ensures that the rectangular boundaries of the upper modules 300 are parallel or perpendicular to the dock width, guaranteeing the feasibility of integration and closure within the dock using the gantry crane 400 and controllable lifting accuracy. If this cannot be guaranteed, the aforementioned requirement for directional symmetry may not be met.

[0032] When determining the location where the area of ​​the damping plate 100 needs to be reduced, if the requirement of symmetry about the direction is not met, consider one of the following two methods: For cylindrical FPSOs with a small number of upper modules 300 and ample space, each upper module 300 is arranged perpendicular to the long side of the living quarters. The damping plate 100 is positioned on one or both sides of the line perpendicular to the long side of the living quarters when the cylindrical FPSO is arranged in the dock, so that the long side of the living quarters is parallel to the width of the dock.

[0033] For cylindrical FPSOs with a large number of upper modules 300 and limited space, each upper module 300 is arranged parallel to the long side of the living quarters along its length, thereby maximizing space utilization. The damping plate 100, which requires a reduced area, is positioned on one or both sides of the line parallel to the long side of the living quarters, so that when the cylindrical FPSO is arranged in the dock, the long side of the living quarters is perpendicular to the width of the dock.

[0034] In some embodiments, when considering the orientation of the upper module 300 and its relative position to the dock, the weight of the module and the lifting capacity of the gantry crane 400 are also considered. If the weight of a certain upper module 300 exceeds the lifting capacity of a single gantry crane 400 and the conditions for lifting by two gantry cranes 400 are met, the length direction of the upper module 300 needs to be arranged along the length direction of the dock.

[0035] Specifically, when considering the orientation of the upper module 300 and its relative position to the dock, the weight of the upper module and the lifting capacity of the gantry crane 400 must also be taken into account. If the weight of a module exceeds the lifting capacity of a single gantry crane 400, but can be lifted by two gantry cranes 400 together, the upper module 300 can be arranged along the length of the dock so that both gantry cranes 400 can lift the upper module 300 simultaneously.

[0036] It should be noted that gantry cranes 400 typically span the width of the dock, and two or more gantry cranes 400 are distributed along the length of the dock.

[0037] The damping plate design method for cylindrical FPSO provided by this invention can ensure the motion performance of cylindrical FPSO in harsh sea conditions, while enabling the hull to be built in a limited dock and making full use of the gantry crane 400 to integrate the superstructure module 300. This comprehensively ensures the performance of cylindrical FPSO, guarantees the construction period, and saves costs.

[0038] Embodiments of the present invention also provide a design method for a cylindrical FPSO, the design method comprising: The damping plate 100 is designed using the damping plate design method of the cylindrical FPSO described above; Based on the shape and dimensions of the damping plate 100 and the width of the dock, determine the undocking structure protection measures corresponding to the structure of the damping plate 100. Determine the design draft of the cylindrical FPSO; Determine the capacity of the ballast tanks and cargo oil tanks of the cylindrical FPSO; Accurately evaluate the motion performance of cylindrical FPSOs; Determine the height of the wave barrier 200 for the cylindrical FPSO.

[0039] In some embodiments, based on the shape and size of the damping plate 100 and the width of the dock, the undocking structure protection measures corresponding to the structure of the damping plate 100 are determined, including determining the diameter of the rubber fender and the gap between the outer side of the rubber fender and the dock wall after the damping plate 100 is installed with the rubber fender.

[0040] Specifically, the damping plate 100 is installed just before undocking to ensure that the crawler crane can move freely within the dock during construction, improving the flexibility of hull construction and integration support work. Before undocking, rubber fenders are installed on the damping plate 100 near the width of the dock to protect it during platform floating and undocking operations. The rubber fenders are approximately 1 meter in diameter, and after installation, the distance between the damping plate 100 and the dock wall in the width direction is approximately 1 meter.

[0041] In some embodiments, the diameter-to-depth ratio (B / D) of a cylindrical FPSO is greater than 2. Determining the design draft of the cylindrical FPSO includes: Determining the maximum draft: Under the premise of meeting the oil storage requirements, the draft is reduced to increase the allowable center of gravity height for stability; when the oil storage tank capacity is insufficient, the maximum draft is calculated backward through stability calculations based on an absolutely conservative center of gravity height. Determine the minimum draft: Under storm conditions, the minimum draft is determined by evaluating whether the damping plate 100 leaks water. The minimum draft is the minimum value under the premise that the damping plate 100 does not leak water.

[0042] Specifically, while meeting oil storage requirements, the draft should be reduced as much as possible to increase the allowable center of gravity height for stability. If the oil storage tank capacity is not met, the maximum draft can be calculated based on a conservative center of gravity height and stability. When determining the stability calculation for the freeboard, the hull compartments do not need to be completely determined, that is, the free surface correction does not need to be accurately considered, in order to improve the flexibility in the early stages of design.

[0043] In some embodiments, the method for determining the minimum draft by assessing whether water is flowing out of the damping plate 100 includes: Obtain the design draft d, the roll or pitch angle θ of the damping plate 100 under storm conditions, the heave amplitude a, the thickness m of the damping plate 100, and the diameter φ of the damping plate 100, and calculate the limiting tilt angle. ; When θ is less than θ lim Then, decrease the design draft by one step and repeat the above steps until θ is greater than θ. lim The calculation is stopped when the minimum draft d is determined.

[0044] In some embodiments, determining the capacity of ballast tanks and cargo oil tanks includes the following steps: The minimum capacity of the ballast tank should be determined so that it is greater than the capacity required for the cylindrical FPSO to reach the predetermined ballast draft. While meeting the minimum capacity requirements of the ballast tank, the cross-section of the cargo oil tank is designed as a regular octagon, and its circumscribed circle radius is maximized.

[0045] Specifically, for a cylindrical FPSO with a waterline diameter of R, a depth of D, and a cargo oil tank height of H, for a regular octagonal cargo oil tank, when the radii of the circumscribed circles are a and b (where b > a), the change in ballast capacity corresponds to a ballast draft of approximately 0.9 (b... 2 -a 2 )*D / R 2 Provided the ballast tank capacity meets the ballast draft, when the diameter of the cargo oil tank increases from a to b, under the same cargo oil loading capacity, the loading height of the cargo oil tank can be reduced (b). 2 -a 2 )*H / b 2 This lowers the center of gravity of the cargo oil loading by approximately (b 2 -a 2 )*H / 2b 2 This increases the GM value of a cylindrical FPSO under full load conditions by approximately (b 2 -a 2 )*2H / 5b 2 This improves the motion performance under full load conditions.

[0046] In some embodiments, a method for accurately evaluating the motion performance of the cylindrical FPSO includes: When conducting stability assessments, the contributions of all non-watertight bulkheads are ignored; When providing stability height (GM) values ​​for motion performance calculations, the actual contribution of non-watertight bulkheads to reducing fluid sloshing within the compartment is taken into account.

[0047] In some embodiments, a method for determining the height of the wave-breaking wall 200 includes: The wave-climbing principle is established, which allows the deck to withstand waves under once-in-a-century environmental conditions, but does not allow the process deck to withstand waves under once-in-a-year operating conditions. While adhering to the principle of wave resistance, the height of the wave barrier should be reduced by 200 mm as much as possible.

[0048] Specifically, the method for determining the 200mm height of the wave barrier needs to ensure that the wave-bearing requirements are met, allowing the process deck to withstand waves under 100-year wave conditions but not under 1-year wave conditions. Local wave protection should be provided for critical equipment in areas subject to 100-year wave conditions. While meeting the wave-bearing requirements, the 200mm height of the wave barrier should be minimized to reduce the risk of oil and gas accumulation, while also providing a clear view and improving the comfort of on-site personnel.

[0049] The design method of the cylindrical FPSO described above will be illustrated below with a specific embodiment: like Figure 2 As shown, taking a cylindrical FPSO with a preliminary diameter of 110m for the damping plate 100 as an example, when the width of the dock at the construction site is less than 110m, the asymmetric damping plate 100 is designed based on the dimensions of the limited dock to adapt to the dock capacity.

[0050] First, the area of ​​the damping plate 100 in certain locations needs to be appropriately reduced so that the width of the damping plate 100 in one direction is about 4m to 8m less than the width of the dock. That is, there should be a distance of 2m to 4m between the two sides of the damping plate 100 and the dock walls on both sides of the dock. In this way, the area of ​​the damping plate 100 is maximized, while there is a certain distance between it and the dock walls for personnel to pass through. At the same time, the risk of collision between the cylindrical FPSO and the dock walls due to movement during the floating process is avoided.

[0051] Based on the established orientation of the cylindrical FPSO, the northeast direction was found to have the most challenging environmental conditions. The upper modules 300 of this cylindrical FPSO are arranged very tightly, with many modules being elongated, and the length of each upper module 300 is parallel to the direction of the living quarters. Because the number of the three sets of mooring cables is not exactly the same, the size of opening A in the damping plate 100 differs from the openings B and C of the damping plate 100, and opening A forms a certain angle with the orientation of the upper modules 300.

[0052] When determining the location where the area to be reduced for the damping plate 100 needs to be prioritized, symmetry with respect to opening A of the damping plate 100 should be prioritized to ensure that the overall performance of the cylindrical FPSO is symmetrical about opening A of the damping plate 100. Considering that the arrangement direction of the upper module 300 forms a certain angle with opening A of the damping plate 100, it will cause the upper module 300 to form a certain angle with the length direction of the dock within the dock, making it impossible for the gantry crane 400 to meet the required closure accuracy. Therefore, it is determined that determining the location where the area to be reduced for the damping plate 100 needs to be reduced at opening A is not feasible.

[0053] Due to the large number of upper modules 300 and the limited space, many of which are elongated, and with the length of each upper module 300 parallel to the long side of the living room building, the damping plate 100 is positioned on either side of the line parallel to the long side of the living room building to reduce its area. Figure 5 As shown, when a cylindrical FPSO is arranged in the dock, the long side of the living quarters is along the length of the dock, such as... Figure 6 As shown. In actual orientation, the position of the damping plate 100 with reduced area is parallel to the direction of the most severe environmental conditions, and the impact on performance is acceptable.

[0054] Damping plate 100 is installed just before undocking to ensure that the crawler crane can move freely within the dock during construction, improving the flexibility of hull construction and integration support work. Before undocking, rubber fenders are installed on the side of damping plate 100 closest to the dock wall to protect it during platform floating and undocking operations. The rubber fenders are approximately 1 meter in diameter, and after installation, the gap between the damping plate 100 and the corresponding dock wall on both sides is approximately 1 meter.

[0055] For flat, chubby cylindrical FPSOs with a diameter-to-depth ratio (B / D) greater than 2, the restoring moment curve is prone to exhibiting a bimodal characteristic, with the angle corresponding to the largest peak being less than 25 degrees, thus failing to meet the stability specification requirement of greater than 25 degrees.

[0056] like Figure 7 and Figure 8 As shown, the study found that with the increase of the center of gravity and draft of the cylindrical FPSO, the second peak in the curve decreases more rapidly, making the first peak more likely to become the maximum peak. Therefore, the design method for determining the maximum draft (freeboard) is as follows: under the premise of meeting the oil storage requirements, the draft should be reduced as much as possible to increase the allowable center of gravity height for stability; when the oil storage tank capacity is not met, the maximum draft can be calculated based on an absolutely conservative center of gravity height and the stability.

[0057] In addition, the assessment found that, Figure 9As shown, free surface correction will reduce the overall recovery moment curve, but will not change the position of the peak. Therefore, when determining the maximum draft, free surface correction can be disregarded, meaning that the hull compartments can be incompletely determined. This is beneficial for improving the efficiency of determining the maximum draft and increasing the flexibility of the design when multiple parameters are not locked in the early stages of design.

[0058] The design method for determining the minimum draft is as follows: While ensuring that the damper plate 100 does not leak water, the smaller the minimum draft, the better. The method for evaluating whether the damper plate 100 will leak water is based on the design draft d, the roll and pitch angles θ of the damper plate 100 under storm conditions, the heave amplitude a, the thickness m of the damper plate 100, the diameter φ of the damper plate 100, and the limiting tilt angle. When θ is less than θ lim If the damping plate 100 is in a certain condition, water will flow out; otherwise, no water will flow out.

[0059] The design method for ballast tanks and cargo oil tanks is as follows: For a cylindrical FPSO with a waterline diameter of R and a depth of D, and a cargo oil tank height of H, for a regular octagonal cargo oil tank, when the radii of the circumscribed circles are a and b (where b > a), the change in ballast capacity corresponds to a ballast draft of approximately 0.9 (b...). 2 -a 2 )*D / R 2 Provided the ballast tank capacity meets the ballast draft, when the diameter of the cargo oil tank increases from a to b, under the same cargo oil loading capacity, the loading height of the cargo oil tank can be reduced (b). 2 -a 2 )*H / b 2 This lowers the center of gravity of the cargo oil loading by approximately (b 2 -a 2 )*H / 2b 2 This increases the GM value of a cylindrical FPSO under full load conditions by approximately (b 2 -a 2 )*2H / 5b 2 This improves the motion performance under full load conditions.

[0060] Cylindrical FPSOs have large individual compartment areas. If free surface correction is considered solely based on stability principles, the design would be overly redundant. Conversely, ignoring free surface correction would result in an insufficiently conservative design. The relationship between the kinematic performance and GM (Gross Mullion) of a cylindrical FPSO differs from that of conventional FPSOs. Therefore, a method for accurately evaluating kinematic performance based on structural models is developed: in stability assessments, any non-watertight bulkheads are disregarded. When using GM for kinematic calculations, the actual structural design is considered. If non-watertight bulkheads are present, their actual contribution to reducing fluid sloshing is taken into account.

[0061] Figure 10This is a cross-sectional elevation view of a typical compartment. Due to structural continuity, there is a structural bulkhead at the bottom. An opening in the bulkhead achieves its non-watertight characteristic, but essentially functions as a sloshing-damping bulkhead, especially when the liquid level inside the compartment avoids the opening location, where its effect is the same as a watertight bulkhead. For several typical compartments, corrections were made according to stability principles and considering the effect of the structural bulkhead, respectively. The comparison of the free surface corrected moments of inertia is shown in the table below. It can be seen that corrections based on the structural model can reduce the redundancy by at least 3 / 4 of the original stability-based correction, which is beneficial for accurately evaluating motion performance.

[0062]

[0063] Table 1 Comparison of Corrected Moments of Inertia for Free Liquid Surfaces The method for determining the 200mm height of the wave barrier above the process deck includes: allowing the process deck to experience waves under 100-year return period environmental conditions, but not allowing waves under 1-year return period operating conditions; and providing localized wave protection for critical equipment in areas prone to waves under 100-year return period environmental conditions. While meeting wave requirements, the 200mm height of the wave barrier should be minimized to reduce the risk of oil and gas accumulation, while also providing a clear view and improving operational comfort for on-site personnel.

[0064] The design method for a cylindrical FPSO provided by this invention ensures the FPSO's maneuverability under harsh sea conditions while allowing for hull construction within a limited dry dock and full utilization of the gantry crane 400 to integrate the superstructure module 300. This comprehensively guarantees the FPSO's performance, ensures the construction period, and saves costs. It improves the dry dock's availability in the width direction and the flexibility of hull construction and integration support work. Collision avoidance measures also ensure the structural safety of the damping plate. While meeting specifications, it increases the cylindrical FPSO's oil storage capacity, balances its performance under various operating conditions, and improves maneuverability under full load conditions. It improves flexibility in the early design phase, reduces design redundancy, and enhances the accuracy of maneuverability assessment. It ensures that the damping plate will not leak water even under harsh sea conditions during service, avoiding the impact load and fatigue effects of frequent water ingress on the damping plate 100. While ensuring the safety of the superstructure equipment and structure, it reduces the risk of oil and gas accumulation and provides a wide field of vision for on-site personnel, improving operational comfort.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and not to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for designing a damping plate for a cylindrical FPSO, characterized in that, The outer diameter of the damping plate (100) is greater than or equal to the width of the dock. The design method includes reducing the area of ​​a local location of the damping plate (100) based on the width of the dock, such that the length of the damping plate (100) in one direction is less than the width of the dock. The location where the area of ​​the damping plate (100) to be reduced needs to satisfy the following conditions: Based on the actual orientation of the cylindrical FPSO in the operating sea area and the directionality of the environmental conditions, the location where the area of ​​the damping plate (100) needs to be reduced should avoid the location corresponding to the direction of the most severe environmental conditions and the most frequent occurrence of severe environmental conditions. Based on the mooring cable arrangement requirements, the orientation of each near-rectangular upper module (300), and the relative position of the upper module (300) to the dock, when the rectangular boundary is parallel or perpendicular to the width direction of the dock, the position where the area of ​​the damping plate (100) is reduced is symmetrical about a line parallel to the rectangular boundary and passing through the center of the damping plate (100). When it is not possible to guarantee that the position where the area of ​​the damping plate (100) is reduced is symmetrical about a line parallel to the rectangular boundary and passing through the center of the damping plate (100), one of the following two methods is considered: For the cylindrical FPSO with ample space for the upper module (300), the length direction of each upper module (300) is perpendicular to the long side of the living room building, and the position of the damping plate (100) with reduced area is selected on one or both sides of the line perpendicular to the long side of the living room building. For the cylindrical FPSO with limited space for the upper module (300), the length direction of each upper module (300) is parallel to the long side of the living room building, and the position of the damping plate (100) with reduced area is selected on one or both sides of the line parallel to the long side of the living room building.

2. The design method for the damping plate of a cylindrical FPSO according to claim 1, characterized in that, When considering the orientation of the upper module (300) and its relative position to the dock, the weight of the upper module (300) and the lifting capacity of the gantry crane (400) are also taken into account. If the weight of a certain upper module (300) exceeds the lifting capacity of a single gantry crane (400) and the conditions for lifting by two gantry cranes (400) are met, the length direction of the upper module (300) must be arranged along the length direction of the dock.

3. A design method for a cylindrical FPSO, characterized in that, include: The damping plate (100) is designed using the damping plate design method of the cylindrical FPSO as described in claim 1 or 2. Based on the shape and size of the damping plate (100) and the width of the dock, determine the undocking structure protection measures corresponding to the structure of the damping plate (100); Determine the design draft of the cylindrical FPSO; Determine the capacity of the ballast tank and cargo oil tank of the cylindrical FPSO; Accurately evaluate the motion performance of the cylindrical FPSO; Determine the height of the wave barrier (200) of the cylindrical FPSO.

4. The design method for a cylindrical FPSO according to claim 3, characterized in that, Based on the shape and size of the damping plate (100) and the width of the dock, the method for determining the undocking structure protection measures corresponding to the structure of the damping plate (100) includes determining the diameter of the rubber fender and the gap between the outer side of the rubber fender and the dock wall of the dock after the damping plate (100) is installed on the rubber fender.

5. The design method for a cylindrical FPSO according to claim 3, characterized in that, The diameter-to-depth ratio (B / D) of the cylindrical FPSO is greater than 2, and the method for determining the design draft of the cylindrical FPSO includes: Determine the maximum draft: Under the premise of meeting the oil storage requirements, the allowable center of gravity height for stability is increased by reducing the draft. When the oil storage tank capacity is insufficient, the maximum draft is calculated by back-calculating the center of gravity height based on an absolutely conservative one. Determine the minimum draft: Under storm conditions, the minimum draft is determined by assessing whether the damping plate (100) leaks water, wherein the minimum draft is the minimum value under the premise that the damping plate (100) does not leak water.

6. The design method for a cylindrical FPSO according to claim 5, characterized in that, When determining the maximum draft, the hull compartments are not fully determined, and the free surface correction is not accurately considered.

7. The design method for a cylindrical FPSO according to claim 5, characterized in that, The method for determining the minimum draft by evaluating whether water is flowing out of the damping plate (100) includes: Obtain the design draft d, the roll or pitch angle θ of the damping plate (100) under storm conditions, the heave amplitude a, the thickness m of the damping plate (100), and the diameter φ of the damping plate (100), and calculate the limiting tilt angle. ; When θ is less than θ lim Then, reduce the design draft by one step and repeat the above steps until θ is greater than θ. lim The calculation is stopped when the design draft d is determined to be the minimum draft at this time.

8. The design method for a cylindrical FPSO according to claim 3, characterized in that, Determining the capacity of the ballast tanks and cargo oil tanks includes the following steps: Determine the minimum capacity of the ballast tank, which is greater than the capacity required for the cylindrical FPSO to reach the predetermined ballast draft. While meeting the minimum capacity requirements of the ballast tank, the cross-section of the cargo oil tank is designed as a regular octagon, and its circumscribed circle radius is maximized.

9. The design method for a cylindrical FPSO according to claim 8, characterized in that, The method for accurately evaluating the motion performance of the cylindrical FPSO includes: When conducting stability assessments, the contributions of all non-watertight bulkheads are ignored; When providing stability height (GM) values ​​for motion performance calculations, the actual contribution of non-watertight bulkheads to reducing fluid sloshing within the compartment is taken into account.

10. The design method for a cylindrical FPSO according to claim 3, characterized in that, The method for determining the height of the wave barrier (200) of the cylindrical FPSO includes: The wave-climbing principle is determined, which means that the deck is allowed to climb waves under environmental conditions that occur once every 100 years, but the process deck is not allowed to climb waves under operating conditions that occur once every year. While satisfying the aforementioned wave-breaking principle, the height of the wave-breaking wall (200) should be reduced as much as possible.

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