Floating storage vessel with expansion section and offshore terminal

Abstract

An offshore terminal facility comprising, in various embodiments, a floating storage vessel with its bow in a fixed orientation and multi-point moored to the offshore seabed by multi-point mooring lines, the floating storage vessel comprising a hull having a bow end and a stern end, the hull being provided with an extension at one or both of the bow end and the stern end, and including a connecting means on the extension for connecting the multi-point mooring lines to the floating storage vessel.

Description

Detailed Description of the Invention

[0001] [Field] The present invention relates to a multi-moored floating storage vessel and an offshore terminal installation in which cargo ships are moored to the multi-moored floating storage vessel for the loading or unloading of fluid cargoes offshore. [background] Floating storage vessels may be used to store bulk quantities of fluid products at offshore locations. Floating storage vessels may be permanently moored at an offshore location and may be visited occasionally by cargo ships for loading or unloading. Examples of this type of floating storage vessel include those referred to in the art as floating storage units (FSUs), floating storage and regasification units (FSRUs), and / or the like.

[0002] Current FSUs are typically converted from former tanker vessels. The conversion of existing, former tankers into floating storage units is typically the preferred option in the industry from technical, schedule, and commercial standpoints.

[0003] US Patent Application Publication US2019 / 0161146 describes a pierless offshore terminal with floating storage units (FSUs) that are multi-point moored to the seabed offshore. In one example, the offshore terminal includes a jack-up platform with facilities for regasification on one side of the floating storage units. Cargo ships are occasionally moored side-by-side on the other side of the floating storage facilities to offload fluid cargo between the ships from the cargo ships to the FSUs. The side-by-side moorings allow hoses for transferring the fluid cargo to be connected between the cargo ships and the FSUs, eliminating the need for a dedicated utility unit to carry the hoses across the ocean to the cargo ships.

[0004] For large cargo ships, the assistance of a tugboat may typically be required to help control the lateral movement of the cargo ship towards the floating storage vessel for side-by-side mooring. Mooring lines for mooring the cargo ship to the floating storage vessel are passed and tensioned between the cargo ship and the floating storage vessel.

[0005] Bringing a large cargo ship alongside a floating storage vessel that is moored with multiple mooring lines in a fixed bow orientation can be particularly challenging when performed under adverse marine and weather conditions. For example, it can be difficult to control the movements of the cargo ship and the supporting tugboats and make the necessary fine adjustments to safely guide the cargo ship into the correct mooring position alongside the floating storage vessel. [overview] In an example disclosed herein, there is provided a floating storage vessel comprising a hull having a bow end and a stern end, an elongated extension projecting horizontally from an upper portion of the hull at either or both of the bow and stern ends, the extension having at least two coupling devices spaced apart from one another on the extension, each coupling device engaging a separate multi-point mooring line. The floating storage vessel may have further features as set out in any of the dependent claims appended hereto or as set out elsewhere in this specification.

[0006] In an example disclosed herein, a floating storage vessel is provided that includes a hull having a bow end and a stern end, the hull being provided with an extension at one or both of the bow end and the stern end, and including a connection means on the extension for connecting a multi-point mooring line to the floating storage vessel.

[0007] Typically the hull will have a hull deck on top of the hull and the extension will be located flush with the hull deck, The extension may comprise a box structure with the extension deck located at or near the level of the hull deck.

[0008] Typically the extension comprises a welded plate box structure. The extension deck is provided on or integrated into the welded plate structure. The connection means may be located on the extension deck or may be accessible to the crew from the extension deck.

[0009] In a particular example, the extension comprises a box-shaped structure extending horizontally from a first end to a second end, the first end of the box-shaped structure connecting to the hull at an upper location on the bow or stern end, the box-shaped structure may be supported by at least one brace member connecting to the box-shaped structure at a location between the first and second ends of the box-shaped structure or at the second end of the box-shaped structure and connecting to the hull at a lower location on the bow or stern end, for example near the position of the propeller if located on the stern or near the position of the bulb if located on the bow.

[0010] In a particular example, the extension comprises a box-type structure comprising welded steel plates, the structure being elongated so as to extend between a first end and a second end, the extension being welded at the first end to join the box-type structure to the hull, without the need for further connection of the box-type structure to the hull or other supports to provide the extension in an operational configuration at the bow or aft ends of the hull.

[0011] Typically, the extension has a first end and a second end and extends in a horizontal extension direction between the first end and the second end, the first end being weldably joined to the hull for mounting the extension on the hull, and the second end being located distally from the joined first end.

[0012] The extensions at either or both of the bow and aft ends may be displaced extensions, which are angularly displaced from the longitudinal axis of the hull. The multi-point mooring line may be or may comprise a multi-point mooring chain.

[0013] In an example disclosed herein, there is provided an offshore terminal installation comprising a floating storage vessel multi-point moored to the offshore seabed by multi-point mooring lines in a fixed orientation at its bow, the floating storage vessel comprising a hull extending along a longitudinal axis, the hull having a bow end and a stern end, at either or both of the bow end and the stern end an elongated extension protruding from the hull parallel to the longitudinal axis, the extension having at least four coupling devices spaced along a portion of the length of the extension, each coupling device engaging a separate multi-point mooring line. The offshore terminal installation may have further features as set out in any of the dependent claims appended hereto or as set out elsewhere in this specification.

[0014] In an example disclosed herein, an offshore terminal facility is provided comprising a floating storage vessel multi-point moored to the offshore seabed by multi-point mooring lines with its bow in a fixed orientation, the floating storage vessel comprising a hull having a bow end and a stern end, the hull being provided with an extension at either or both of the bow end and the stern end, and including a connecting means on the extension for connecting the multi-point mooring lines to the floating storage vessel.

[0015] A mooring area for mooring a cargo ship to the floating storage vessel may be provided within a defined area of ​​the side of the floating storage vessel between the multi-point mooring lines at the bow end and the multi-point mooring lines at the stern end, thereby allowing the cargo ship to be easily moored to the side of the floating storage vessel without the hull of the cargo ship overlapping or interfering with the multi-point mooring lines.

[0016] In some examples, the floating storage vessel comprises a bow extension and a stern extension, the cargo vessel is moored in a mooring area on the side of the floating storage vessel between the extensions, and a connecting means on the extensions defines the starting point of a multi-point mooring line from the floating storage vessel, thereby maintaining at least a predetermined distance or spacing horizontally between the multi-point mooring line and a close point at the moored cargo vessel, e.g., at the bow or stern of the cargo vessel.

[0017] Via the extension, a mooring area can be provided, thus allowing a large cargo ship to be moored alongside the floating storage unit with a safe distance between the cargo ship and the multi-point mooring lines of the floating storage unit. The provided mooring area can thus facilitate access for a tugboat to assist in mooring the cargo ship close to the floating storage vessel, as well as facilitating safe movement and control of the cargo ship when adjacent to the side of the floating storage vessel. The tugboat can be coupled to or positioned relative to the vessel, with more options for the tow line configuration and the contact points of the tugboat to the cargo ship, so that the movement of the cargo ship can be more finely controlled and adjusted when it is brought alongside the floating storage vessel.

[0018] Cargo ships can be deployed and moored more easily, dealing with difficult marine conditions. Thus, terminals are provided for floating storage vessels in the form of previously used tankers, typically having a length of 250m to 300m, which have been modified to provide an extension, and for cargo ships in the form of currently used tanker vessels, e.g. of the same type, length and capacity as the original floating storage vessels.

[0019] A match or similarity in size between the cargo vessel and the floating storage vessel can be beneficial to optimize operations. It is therefore advantageous for the length of the cargo vessel to be equal to the length of the hull of the floating storage vessel, or typically differ by less than 5%. However, the cargo vessel may otherwise be of any length and configuration that allows for side-by-side mooring. In certain variations, the length of the cargo vessel may differ in length by 5% to less than 50% from the length of the hull of the floating storage vessel. The length of the hull of the floating storage vessel may be the length of a pre-modified hull to which the extensions in embodiments of the present invention are added. The cargo vessel may be longer or shorter than the floating storage vessel and / or longer or shorter than the pre-modified hull.

[0020] Typically, the offshore terminal facility further comprises a cargo ship, moored to the floating storage vessel in a side-by-side relationship for transferring fluid cargo between the cargo ship and the floating storage vessel. The cargo ship is moored in a mooring area between a multi-point mooring line at the bow end and a multi-point mooring line at the stern end. The side-by-side mooring allows for a relatively short cargo transfer hose between the cargo ship and the floating storage vessel and reduces pressure losses when transferring fluids through the hose, resulting in a higher transfer capacity, while the mooring with an extension allows the cargo ship to come alongside more efficiently or even in adverse weather conditions. Thus, the terminal may provide improvements such as increased operating time, more efficient use of available cargo transfer time slots, and reduced time to complete cargo transfer.

[0021] Typically, the offshore terminal installation further comprises a first pipe for transferring fluid cargo between the cargo vessel and the floating storage vessel. The cargo vessels are typically moored such that their amidships manifold is located opposite the amidships manifold of the floating storage vessel. Thus, the first pipe, typically comprising one or more hoses, may extend between the respective cargo vessel amidships manifold and the floating storage vessel amidships manifold.

[0022] Typically, the offshore terminal facility further comprises a platform or transfer tower supported on the seabed and a second pipe for transferring the fluid cargo or gas between the floating storage vessel and the platform or transfer tower.

[0023] Optionally, the platform may include a regasification facility for regasifying the offloaded fluid, and the apparatus may include a third pipe for transmitting the regasified fluid from the platform to shore, which may comprise a subsea pipeline, for example on the seabed.

[0024] Alternatively, the platform may include a liquefaction facility for liquefying fluid stored in the floating storage unit for transfer to the cargo vessel, and the apparatus may include a third pipe for transmitting the gas to the platform, which may comprise a subsea pipeline.

[0025] The platform or transfer tower is preferably located on the opposite side of the floating storage vessel to the cargo ship. The platform may conveniently be an elevated platform having legs arranged to rest on the seabed and a hull elevated along the legs and positioned above the wave zone on the sea surface.

[0026] Because the regasification or liquefaction equipment may be installed on a platform or support structure, such equipment and other equipment such as cranes or lifting arms for connecting the second pipes, etc. may not be required on the floating storage vessel, and thus the floating storage vessel used for the terminal may be conveniently provided without the need for major modifications, which may help limit the time required for installation and assembly of the terminal.

[0027] Typically, the hull of the floating storage vessel is modified from the original hull by adding an extension, which may typically be a pre-fabricated unit, on the bow or stern end. The extension may comprise a cantilever protruding from the original bow or stern end. The extension may be long enough to position the connection point of the multi-point mooring chain on the extension beyond the original bow or stern end, so that a cargo ship, preferably the same size as the original, i.e. unmodified, floating storage vessel, but possibly slightly longer, can be safely moored alongside between the multi-point mooring chains at the bow end and the multi-point mooring chains at the stern end, without the cargo ship's hull or tug interfering with or overlapping horizontally with the multi-point mooring lines extending laterally from the floating storage vessel.

[0028] The multi-point mooring lines are preferably provided in a suspended configuration, in which one end of the multi-point mooring lines is connected to a connecting means as high as possible above sea level, for example at or near deck level of the floating storage vessel and / or extension, and the other end of the multi-point mooring lines is connected to a submerged mooring member on the seabed.

[0029] The offshore terminal is preferably a shallow water offshore terminal. The floating storage vessel may be multi-point moored in shallow waters with depths in the range of up to 50m. Thus, the system may be used for loading and unloading fluid cargoes at suitable locations in shallow coastal waters and transporting the fluids to shore via relatively short subsea pipelines.

[0030] To obtain an acceptable suspension geometry for the mooring lines of the suspended structure, it may be preferable to use multi-point mooring lines attached to the deck or attached to the floating storage vessel as high above sea level as possible, i.e. not attached to the keel, which may allow dynamic vessel motions of the floating storage vessel with acceptable mooring line forces in high wave conditions.

[0031] A multi-point mooring line, e.g., a multi-point mooring chain, at the bow end extends away from the floating storage unit at a first divergence angle relative to the longitudinal axis of the floating storage vessel, and a multi-point mooring line, e.g., a multi-point mooring chain, at the stern end extends away from the floating storage vessel at a second divergence angle relative to the longitudinal axis of the floating storage vessel.

[0032] The fluid cargo may be any fluid cargo, such as, for example, any one or more of a fluid, a gas, a mixture of fluid and gas, liquefied natural gas (LNG), liquefied petroleum gas (LPG), liquefied ammonia, liquefied hydrogen, liquefied carbon dioxide (CO2), or the like.

[0033] In an example disclosed herein, a method of using an offshore terminal facility is provided, the method comprising: multi-point mooring a floating storage vessel to the offshore seabed by multi-point mooring lines in a fixed bow orientation, the floating storage vessel comprising a hull having a bow end and a stern end, the hull being provided with an extension at either or both of the bow end and the stern end, the extension including a connecting means for connecting the multi-point mooring lines to the floating storage vessel; and offloading a fluid cargo from the cargo vessel to the floating storage vessel.

[0034] In certain examples, the method may further comprise transferring the offloaded fluid cargo from the floating storage vessel to shore using a transfer tower. In other particular examples, the method may further include any one or more of: transmitting the offloaded fluid cargo from the floating storage vessel to one or more platforms; processing the fluid cargo including liquefied gas on the one or more platforms; regasifying the liquefied gas to produce regasified gas; generating electricity using the regasified gas; generating water using the generated electricity; and transmitting or transporting the regasified gas, the generated electricity, or the generated water to shore or another facility.

[0035] In an example disclosed herein, a method of using an offshore terminal facility is provided, the method comprising: multi-point mooring a floating storage vessel with its bow multi-point moored to the offshore seabed by multi-point mooring lines in a fixed orientation, the floating storage vessel comprising a hull having a bow end and a stern end and provided with an extension at either or both of the bow end and the stern end, the extension including a connecting means for connecting the multi-point mooring lines to the floating storage vessel; and loading a fluid cargo from the floating storage vessel onto a cargo vessel.

[0036] In certain examples, the method may further comprise transferring the fluid cargo from shore to the floating storage vessel. In a particular example, the terminal facility may include at least one platform, and the method may include conveying gas from shore to the platform, processing the gas on the platform, liquefying the gas, and transferring the liquefied gas from the platform to the floating storage vessel, wherein the loaded fluid cargo comprises a quantity of liquefied gas.

[0037] In an example disclosed herein, there is provided an extension for a floating storage vessel comprising a hull with one or more holds or tanks therein for storing fluid, the hull extending along a longitudinal axis between bow and stern ends, the extension comprising an elongated structure extending parallel to the longitudinal axis between a first end and a second end, the first end of the structure being fixed to the stern or bow end of the hull and the second end being located distally from the stern or bow end, and a plurality of coupling devices spaced apart along the structure for connecting multi-point mooring lines to the extension. The extension may have further features as set out in any of the dependent claims appended hereto or elsewhere herein.

[0038] In an example disclosed herein, an extension for a floating storage vessel is provided that includes a hull having one or more holds or tanks therein for storing a fluid, the hull having a longitudinal axis and extending longitudinally between a bow end and a stern end, the extension comprising a structure extending between a first end and a second end, the first end of the structure configured to be secured to the stern or bow end of the hull and the second end located distally from the stern or bow end, and a connecting means supported on the structure for connecting a multi-point mooring line to the extension.

[0039] Typically the structure comprises or consists essentially of welded steel plates. Typically the structure comprises an elongated box structure or is an elongated box structure.

[0040] Typically, the first end of the structure is joinable to a bow or aft end of the hull to join the structure to the hull. The structure may be configured such that the joining of the first end of the box structure alone is sufficient to support the structure for operational purposes.

[0041] Typically the structure has a deck for crew access to the hookup means, the hookup means being supported on the deck. Typically, the hull includes a hull deck and the structure is configured to connect to the hull, such that the structure is flush with the hull deck.

[0042] Typically the structure extends from a first end to a second end in a longitudinal direction relative to the hull. Alternatively, the structure extends from the first end to the second end in a direction that is angularly displaced from the longitudinal axis of the hull. The structure may include a curve or dogleg between the first and second ends of the structure such that the structure along the curve or dogleg extends away from the longitudinal direction of the hull.

[0043] In an example disclosed herein, a method is provided for providing a multi-point moored floating storage vessel to facilitate loading or unloading operations of fluid cargo at an offshore terminal, the method comprising providing a tanker vessel having one or more tanks or holds for storing fluid and a hull extending between a bow end and a stern end, the tanker vessel being expected to be converted in a conversion process into a floating storage vessel for multi-point mooring in a fixed bow orientation at an offshore terminal, and providing at least one prefabricated extension. the extensions comprising a structure extending between a first end and a second end and coupling means supported on the structure for coupling multi-point mooring lines to the extensions, connecting the first end of the prefabricated structure to a bow or stern end of the hull and attaching the extensions to the hull and positioning the second end of the structure distal from the stern or bow end, obtaining a floating storage vessel provided with at least one extension and multi-point mooring the floating storage vessel to a mooring member on the seabed using the coupling means on the extensions for coupling the multi-point mooring lines to the extensions. The method may further comprise, prior to the conversion, operating the tanker vessel to transport a fluid cargo across the ocean from one location to another, and, after the conversion, operating the floating storage vessel at an offshore terminal to store fluids to be loaded onto the cargo vessel or to store fluids to be unloaded from the cargo vessel.

[0044] An example disclosed herein includes an offshore fluid cargo handling facility including an offshore platform for processing the fluid cargo, and a floating storage vessel multi-point moored adjacent to the offshore platform by a plurality of multi-point mooring lines, the floating storage vessel comprising a hull extending along a longitudinal axis, the hull having bow and stern ends with elongated extensions projecting from the hull parallel to the longitudinal axis at each of the bow and stern ends, each extension having a first elongated side and a second elongated side and a floating storage vessel having at least three coupling devices spaced longitudinally from one another along each long side, one of a plurality of multi-point mooring lines attached to each coupling device, one or more aerial fluid cargo hoses extending between the offshore platform and the floating storage vessel, and a fluid cargo vessel having bow and aft ends, the fluid cargo vessel being moored to the floating storage vessel such that the bow and aft ends of the fluid cargo vessel are spaced from the multi-point mooring lines of the floating storage vessel. The offshore fluid cargo handling installation may have further features as set out in any of the dependent claims appended hereto or as set out elsewhere in this specification.

[0045] Embodiments of the present invention may be advantageous in various ways, as will become apparent throughout this specification. [Brief description of the drawings]

[0046] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1] FIG. 1 is a plan view of an offshore terminal facility in which a cargo ship is moored in a side-by-side relationship with a floating storage vessel, according to an example. [Diagram 2] FIG. 2 is a plan view showing a cargo ship pulled alongside a floating ship for mooring to the floating storage vessel as depicted in FIG. 1. [Diagram 3] FIG. 1 is a plan view of an offshore terminal facility including a transfer tower, according to another embodiment. [Figure 4A] FIG. 4 is a front perspective view of the offshore terminal facility of FIG. [Figure 4B] FIG. 4 is a rear perspective view of the offshore terminal facility of FIG. 3. [Diagram 5] FIG. 1 shows a plan view of an offshore terminal installation with floating storage displaced extensions at each of the bow and stern ends to allow for greater safety spacing between vessels. [Figure 6] FIG. 2 is an enlarged schematic side view of the bow end of the floating storage vessel with an extension. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] [Detailed Description] 1 and 2, the offshore terminal facility 1 comprises a floating storage vessel 10 that is multi-moored to the seabed offshore. At the bow end 10a, the floating storage vessel 10 is provided with a first extension 15a, and at the stern end 10b, the floating storage vessel 10 is provided with a second extension 15b. On each extension 15a, 15b, a connecting means is provided for connecting a multi-point mooring line 16a, 16b to the extension 15a, 15b, respectively.

[0048] The storage vessel 10 is multi-point moored to the seabed in a bow-fixed orientation by multi-point mooring lines 16a, 16b. The multi-point mooring line 16a at the bow end extends from the bow end extension 15a to a mooring member 18a on the seabed. The multi-point mooring line 16b at the stern end extends from the stern end extension 15b to a mooring member 18b on the seabed. Each multi-point mooring line 16a, 16b has a first end connected to a connecting means 86a, 86b on the extension 15a, 15b and a second end connected to a mooring member 18a, 18b. The first ends of the multi-point mooring lines 16a, 16b are connected to the extensions 15a, 15b above sea level, typically at or near deck level of the hull or extension of the floating storage vessel. The second ends of the multi-point mooring lines 16a, 16b are connected underwater to the seabed mooring members 18a, 18b at or near the seabed, so that the multi-point mooring lines 16a, 16b penetrate the water surface on their path from the extensions 15a, 15b to the seabed mooring members 18a, 18b.

[0049] Multi-point mooring lines 16a extend away from the floating storage vessel 10 in direction D, forming a spread angle α with respect to the longitudinal axis 19 of the floating storage vessel. Multi-point mooring lines 16b extend away from the floating storage vessel 10 in direction E, forming a spread angle β with respect to the longitudinal axis 19 of the floating storage vessel 10 in the opposite direction to spread angle α.

[0050] A mooring area 33 is defined on the side of the floating storage vessel between the multi-point mooring rope 16a at the bow end and the multi-point mooring rope 16b at the stern end. In Figure 1, the cargo vessel 20 is moored in a parallel side-by-side configuration in a secure mooring area 33 at the side of the floating storage vessel. The cargo vessel 20 is moored to the floating storage vessel 10 by mooring lines 26a, 26b at the bow and stern ends. The cargo vessel 20 leans against the floating storage vessel via soft fenders 27 located between the opposing hull sides of the floating storage vessel 10 and the cargo vessel 20.

[0051] In Figure 2, the cargo ship 20 is approaching the floating storage vessel 10 by moving laterally towards a safe mooring area 33 as indicated by arrow A. The cargo ship 20 is moved using its own thrusters and is further supported by a number of tugboats 43, some of which push and some of which pull, controlling the speed and position of the cargo ship 20.

[0052] The extensions 15a, 15b position the mooring lines 16a, 16b away from the cargo ship 20. A safety clearance 34a, 34b is established between the hull of the moored cargo ship 20 and the nearest mooring lines 16a, 16b at each end of the mooring. The extensions are preferably provided such that the defined safety clearance provides a clearance of at least 20m between the mooring lines 16a, 16b and the cargo ship when moored. The hull of the cargo ship 20 is typically of the same or similar length as the hull of the floating storage vessel 10 before the extensions 15a, 15b are provided. The mooring area 33 allows a cargo ship 20 of the same or slightly larger size than the floating storage vessel to come alongside more easily and / or in a controlled manner under adverse conditions. The tugboat 43 that may be required to assist the cargo ship 20 may be operated in a more favorable position with respect to the cargo ship and may operate in an operating area between the multi-point mooring lines at the bow end and the multi-point mooring lines at the stern end, while keeping a predefined clearance distance to the nearest mooring lines, e.g., the same distance as the safety clearance. Before the cargo ship is completely alongside the floating storage vessel, the tugboat may operate in the mooring area 33. Thus, the multi-point mooring configuration may make it feasible for the fluid cargo to be transferred side-by-side from the large tanker ship. Cargo ships 20, e.g., tanker ships, for the transportation of fluid cargo and for offloading or loading at offshore fluid transfer terminals are typically "off-the-shelf" available as part of the global fleet, but are typically of similar size and with limited variations. In the prior art, situations may frequently occur where the floating storage vessel 10 is of the same type, i.e. a disused cargo vessel, and the available cargo vessels are not suitable for mooring alongside the floating storage vessel. The solution with the extensions 15a, 15b allows the multi-point mooring of the floating storage vessel with a greater degree of freedom in terms of maneuvering the cargo vessel 20 safely alongside the floating storage vessel. The cargo vessel 20 can be moored close to the side towards the multi-point mooring chains without exceeding the safety clearance 34a, 34b. The provision of the extensions 15a, 15b on the floating storage vessel 10 allows conveniently providing the appropriate safety clearance for the terminal for the specific project requirements and size of the cargo vessel 20, taking into account the possible marine weather conditions as well.

[0053] Continuing to refer to Figures 1 and 2, the offshore terminal installation 1 further comprises a platform supported on the seabed, in this example a lifting platform 50, which comprises a treatment installation 52 for treating the fluid cargo. The platform 50 is installed on the other side of the floating storage vessel in the area between the multi-point mooring chain at the bow end and the multi-point mooring chain at the stern end. For the purposes of this example, the treatment installation 52 is a regasification installation for regasifying the gas from the floating storage vessel that is offloaded from the cargo vessel. In other variants, the treatment installation 52 may be a combined regasification and power generation installation, and may also include a system for producing fresh water. Alternatively, the platform may be a liquefaction installation for liquefying the gas stored in the floating storage vessel that is offloaded to the cargo vessel. The lifting platform 50 comprises a number of legs supported on the seabed and a hull that is lifted along the lifting legs over the wave area to a position above the sea level. A crew bridge 51 spans the ocean above sea level and extends between the platform 50 and the floating storage vessel 10.

[0054] In use, a fluid cargo in the form of liquefied gas is offloaded from the cargo ship 20 to the floating storage vessel 30 via a first pipe in the form of one or more aerial hoses 61 or other loading device connecting between the manifolds 12, 22 amidships of the floating storage vessel 10 and the cargo ship 20. The offloaded liquefied gas is stored in the floating storage vessel 30. The liquefied gas is conveyed via a second pipe in the form of one or more aerial hoses to the platform 50 and regasified by the regasification facility. The regasified gas is then sent away from the platform 50, typically to shore, via a gas pipeline 63.

[0055] In the variant where the processing facility on the platform 50 is a liquefaction facility, in use gas is typically sent from shore to the platform via a gas pipeline 63. The gas is liquefied by the liquefaction facility and conveyed via a second pipe hose 62 to the floating storage vessel 10 where the liquefied gas is stored. The liquefied gas is loaded from the floating storage vessel 10 onto the cargo ship 20 via a first pipe hose 61.

[0056] Referring now to Figures 3, 4A and 4B, the offshore terminal installation 101 is a variation of the installation 1 described above, which includes a transfer tower 150 instead of a raised platform. The transfer tower is supported on the seabed at its base. The tower extends upward through the sea surface and above the wave action zone to a height close to deck level or the height of the amidships manifold 112. An aerial hose 62 extends between the transfer tower 150 and the amidships manifold 112 of the floating storage vessel 10 above the wave action zone to minimise the risk of damage to the hose from wave forces during extreme wave conditions. A third tube in the form of a pipeline 63 typically extends from the base or submerged part of the tower along the seabed. In use, fluid is transferred between the floating storage vessel 30 and the pipeline 63 via the tower and hose 62. To transfer the fluid cargo between the hose 62 and the pipeline 63 during offloading or loading operations, the tower 150 has a conduit running along the tower, for example, from an upper end above sea level to a lower end underwater. In this example, the liquefaction or regasification may be carried out onshore. Thus, the fluid cargo is transferred directly from or to the floating storage vessel 10, without being treated, via the transfer tower 150. In this case, the pipeline may be insulated to keep the gas in fluid form, and may be, for example, a pipe-in-pipe pipeline.

[0057] In Fig. 6 the bow end of the floating storage vessel 10 is depicted in more detail with the extension 15a provided at the bow end. To provide the floating storage vessel 10 with the extension 15a as depicted in Fig. 6, a designated tanker vessel to be adapted is provided with a hull 71 and one or more tanks 13 therein, and the extensions 15a, 15b are provided at the designated tanker vessel hull 71. To facilitate this, the extensions 15a, 15b comprise a prefabricated box-type structure 80 ready to be provided at the tanker vessel. It will be understood that the extension 15b may be configured in a corresponding manner to the extension 15a described herein for the bow end and may be connected to the aft end. Thus, for simplicity, only the bow end configuration and the extension 15a will be described in detail below.

[0058] The box-type structure 80 is configured to fit into the bow end 73 at a connection 73h on the bow end, where it is welded to the bow end 73 of the hull 71. One or more tanks 13 are provided within the hull 71 for storing fluids offloaded from or loaded onto the cargo vessel during use. The box-type structure 80 extends longitudinally away from the connection 73h. In other examples, the box-type structure 80 may comprise a prismatic structure.

[0059] Above the hull 71, the vessel has a hull deck 79 that provides a walkway and / or area for access by the crew and / or crew. Other decks (not shown) may be provided as part of the superstructure on the hull. The hull deck 79 may be provided with handling equipment that can be operated, accessed, and / or inspected by the crew on board, including, for example, cargo handling equipment or mooring equipment to facilitate mooring the cargo vessel 20 to a ship's side. Crew standing on the hull deck 79 can also access the manifold 12 in the midships to facilitate connection of one or more fluid cargo transfer hoses 61 for loading or unloading fluid cargo into or from the holds or tanks 13 within the hull. The midsection of the hull 71 between the aft and bow ends defines the maximum width of the hull 71. The width of the hull 71 from a particular location along the hull 71 typically narrows gradually from the overall width of the midsection toward the bow end 73 and the aft end, respectively.

[0060] The box structure 80 of the extension 15a preferably comprises welded steel plates. The height H of the box structure 80 is preferably less than the freeboard height F of the hull 71 above the waterline 36 and the width is preferably less than the maximum width of the hull at the mid-section, for example typically less than half or less than a quarter of the maximum width of the hull at the mid-section.

[0061] The box-shaped structure 80 extends from a first end 81 to a second end 82. The first end 81 of the box-shaped structure 80 is positioned and welded to the bow end 73 at the connection 73h, connecting the box-shaped structure 80 to the hull 71. The box-shaped structure 80 is elongated and extends longitudinally in the longitudinal direction of the hull from the first end 81 to the second end 82 at the connection 73h. Thus, the box-shaped structure 80 provides a longitudinal extension starting from the hull at the bow end. The structure projects longitudinally from the outer surface of the bow end at the connection 73h towards the second end 82, which is positioned distal to the first end 81.

[0062] Furthermore, the box-type structure 80 is arranged to be welded to a connection 73h on the bow end 73 at or near the top of the hull such that the box-type structure 80 is aligned with the hull deck 79. In this way, the hull 71 can support the box-type structure 80 with the connection means 86a on the box-type structure for the multi-point mooring lines 16a located high above the hull, and by welding the first end 81 to the bow end 73, can benefit from the inherent strength of the hull 71 at or near the level of the hull deck to handle the required mooring loads.

[0063] Additionally, the extension 15a includes an extension deck 89 on top of the box-type structure 80. As shown in Figure 6, when the extension 15a is attached to the hull 71, the deck 89 of the extension 15a is located at or near the same height as the hull deck 79. This arrangement facilitates a strong and robust welded structural connection of the box-type structure 80 to the hull 71.

[0064] In the example of Fig. 6, the box-type structure 80 is further supported by tubular braces 91, which extend from one end 91a connected to the box-type structure 80 at a position along the box-type structure 80 in the elongation direction to the other end 91b connected to the bow end at a lower connection 73i, which is located at a lower position than the connection 73h, for example at or near the waterline 36, such as at or near the bulb 73b at the bow end or at or near the propeller in case of the aft extension 15b. However, in other examples, it may be sufficient to connect the box-type structure 80 at the bow end of the hull with an end welded to the outer surface of the hull, provided that the box-type structure 80 starts at the bow end of the hull and extends longitudinally from a first end 81 to a second end 82 at the connection 73h. In this way, the box-shaped structure 80 (with only a first end 81 connected at 73h) can fully withstand the mooring loads separated from the multi-point mooring line 16a by the forces separated by the floating storage vessel 10 under prevailing marine weather conditions.

[0065] The extension 15a typically comprises a prefabricated welded steel plate structure 80 that can be manufactured in time at the shipyard before the tanker ship arrives at the shipyard. The connection means 86a for the mooring chains will typically be installed on the prefabricated extension 15a before the ship arrives, so that when the ship arrives at the shipyard, everything is ready. In this way, the ship only needs to stay at the shipyard for a limited time, since the extension 15a can be "added" on board, i.e. quickly welded.

[0066] In practice, the box structure 80 or other welded plate structure may be, for example, 5m or more in height. The length of the extension 15a may be determined on a project-by-project basis depending on the size of the cargo ships 20 that are to be moored to the floating storage vessel 10 in a side-by-side mooring arrangement.

[0067] Connection means 86a are provided in the extensions 15a for connecting mooring lines 16a, typically in the form of mooring chains, to the extensions 15a. Although the drawings show six mooring lines per extension, typically there are 6-10 chains per extension, where each chain may be connected to an individual connection means 16a. The connection means 86a in some examples are "adjustable" so that after the chain is towed, the tension in the chain may be adjusted by further towing or slackening the chain using the adjustable connection means. The adjustable means may be used to re-tension the mooring lines 16a as needed, for example, after the vessel 10 has been operating for some time. In some examples, the connection means 86a are equipped with load monitoring devices that continuously monitor the load on the mooring chains during operation. This ensures that the mooring tension is evenly distributed among all the chains. Load monitoring may be particularly beneficial during heavy weather operations to ensure that the mooring tension is within acceptable levels. In some examples, the connecting means 86a is of the releasable type, i.e., the connecting means 86a has a release mechanism so that the mooring line 16a can be released from the extension 15a when the ship 10 has to leave the location (e.g. during very bad weather). Such a release mechanism can be operated remotely, for example by hydraulic or other means. The connecting means 86a is supported on the deck 89 of the extension 15a, typically at or near the level of the extension deck. The connecting means 86a on the extension 15a is sufficient and carries the necessary connection means to connect the multi-point mooring line 16a to the ship at the bow end, without the need to connect the mooring line 16a to the hull between the extensions. The same applies equally to the stern using the extension 15b. In this way, a mooring area for the cargo ship 20 can be defined on the side of the floating storage vessel 10 between the extensions 15a, 15b.

[0068] The offshore terminal installation 201 of Fig. 5 is similar to the installation 1 described above, but the floating storage vessel 10 in this example is provided with displaced extensions 215a, 215b at the bow and stern ends 10a, 10b, i.e. the starting points of the multi-point mooring lines 16a, 16b originating from the extensions 215a, 215b are located away from the central longitudinal axis 19 of the vessel 71. In particular, the extensions 215a, 215b in this example extend from proximal first ends 281a, 281b connected to the vessel's bow or stern, i.e. retrofit welded, towards distal second ends 282a, 282b in a displaced direction extending at an angle Y, Y' from the central longitudinal axis of the vessel 71. The extension 215a is welded at a first end 281a, 281b to the bow or stern end of the ship 10 and extends from the outer surface of the hull on the bow or stern end. The connection means 86a, 86b provide a starting point on the extension 215a, 215a for the mooring line 16a, 216b towards the mooring member on the seabed. The displaced extension 215a, 215b is angled away from the longitudinal axis 19 and away from the side of the ship 10 where the mooring area 33 is provided for the visiting cargo ship 20. This allows a larger clearance or safety distance 234a, 234b between the multi-point mooring line 16a, 16b and the cargo ship 20 when moored in the mooring area 33. By varying the angles Y, Y' and the length between the first and second ends of the displaced extensions 215a, 215b, an optimized safety clearance 234a, 234b can be obtained for a particular project requirement and size of the cargo vessel 20. The angle of displacement can be varied in various instances depending on the requirements. The displaced extensions 215a, 215b can be configured otherwise in terms of the structure and connections described above with respect to any of the other extensions described above.

[0069] In any of the examples described herein, the floating storage vessel may be a floating storage unit (FSU), and in certain examples, the floating storage unit may be a floating storage and regasification unit (FSRU).

Claims

1. A floating storage vessel, 1. A floating storage vessel comprising: a hull having a bow end and a stern end, the hull having an elongated extension projecting horizontally from an upper portion of the hull at one or both of the bow end and the stern end, the elongated extension having at least two spaced apart coupling devices thereon, each coupling device engaging a separate multi-point mooring line.

2. A floating storage vessel as described in claim 1, The floating storage vessel, wherein the elongated extension includes an extension deck.

3. 3. The floating storage vessel of claim 2, the hull comprises a hull deck; the elongated extension is positioned flush with the hull deck; The floating storage vessel, wherein the elongated extension comprises a box structure of welded plates and the extension deck on the box structure.

4. A floating storage vessel according to claim 2 or 3, The floating storage vessel, wherein the coupling device is disposed on the extension deck.

5. A floating storage vessel according to claim 2 or 3, The floating storage vessel, wherein the coupling device is accessible to crew from the extension deck.

6. A floating storage vessel as described in claim 1, the elongated extension comprises a box-like structure extending horizontally from a first end to a second end; the first end of the box-shaped structure is connected to the hull at an upper position on the bow end or the stern end, The box structure may be supported by at least one bracing member; The at least one bracing member is connected to the box-shaped structure at a position between the first end and the second end of the box-shaped structure or at the second end of the box-shaped structure, and is further connected to the hull at a lower position at the bow end or the stern end, the lower position being near the position of the propeller when located at the stern, and near the position of the bulb when located at the bow.

7. A floating storage vessel as described in claim 1, the elongated extension comprises a box structure comprising welded steel plates; the box-shaped structure is elongated so as to extend between a first end and a second end; the elongate extension is welded at the first end to connect the box structure to the hull at the bow end or the stern end; the connection of the first end of the box-shaped structure is the only required connection of the box-shaped structure to the hull.

8. A floating storage vessel as described in claim 1, the elongate extensions at either or both of the bow end and the stern end have first and second ends, the first ends of the elongate extensions being connected to the hull at the bow end or the stern end and extending longitudinally of the hull from the first ends toward the second ends.

9. A floating storage vessel as described in claim 1, the hull has a longitudinal axis; the elongate extensions at either or both of the bow end and the aft end are displaced extensions; The floating storage vessel, wherein the displaced extension extends from a first end connected to the hull at the bow end or the stern end toward a second end at an angle away from the longitudinal axis.

10. An offshore terminal facility comprising:

1. An offshore terminal installation comprising: a floating storage vessel multi-point moored to the offshore seabed with its bow in a fixed orientation by multi-point mooring lines, the floating storage vessel comprising a hull extending along a longitudinal axis, the hull having a bow end and a stern end, and at either or both of the bow end and the stern end, elongated extensions projecting from the hull so as to be parallel to the longitudinal axis, the elongated extensions having at least four spaced apart coupling devices disposed along a portion of the length of the elongated extensions, each coupling device engaging a separate multi-point mooring line.

11. 11. The offshore terminal facility of claim 10, further comprising: Equipped with cargo ships, the cargo vessel is moored to the floating storage vessel in a side-by-side relationship for transferring fluid cargo between the floating storage vessel and the cargo vessel; The offshore terminal facility, wherein the cargo ship is moored in a mooring area between the multi-point mooring line at the bow end and the multi-point mooring line at the stern end.

12. 11. An offshore terminal facility according to claim 10, comprising: the floating storage vessel comprises a bow extension and a stern extension; the cargo ship is moored in a mooring area on the side of the floating storage vessel between the bow extension and the stern extension; the connecting devices on the bow extension and the stern extension define starting points for the multi-point mooring lines, thereby maintaining at least a predetermined distance or spacing horizontally between the nearest multi-point mooring lines and the moored cargo ships in the mooring area.

13. 12. The offshore terminal facility of claim 11, further comprising: a first pipe for transferring fluid cargo between the floating storage vessel and the cargo vessel; a platform or transfer tower supported on the seabed and positioned on an opposite side of the floating storage vessel from the cargo vessel; a second pipe for transferring fluid cargo between the floating storage vessel and the platform or the transfer tower; a third pipe for transferring said fluid cargo between said platform or said transfer tower and shore; Offshore terminal facilities equipped with:

14. 14. The offshore terminal facility of claim 13, further comprising: the platform, wherein the fluid cargo is a liquefied gas; a regasification facility on said platform for regasifying said liquefied gas; Offshore terminal facilities equipped with:

15. 1. An extension for a floating storage vessel comprising a hull with one or more holds or tanks within the hull for storing fluids, The hull extends along a longitudinal axis between a bow end and an aft end; The extension portion is an elongated structure extending parallel to the longitudinal axis between a first end and a second end, the first end of the elongated structure being fixed to the stern or bow end of the hull and the second end being located distally from the stern or bow end; a plurality of spaced apart coupling devices along the elongated structure for connecting multi-point mooring lines to the extensions; The extension comprises:

16. 16. The extension of claim 15, the elongated structure comprises an elongated box structure comprising welded steel plates or is an elongated box structure comprising welded steel plates and further comprising a deck for access by the sailors or crew; The plurality of coupling devices are disposed along the deck.

17. 17. An extension according to claim 15 or 16, The elongated structure extends from the first end to the second end along a curve or dogleg.

18. 16. The extension of claim 15, the elongated structure has a first side and a second side extending between the first end and the second end; The plurality of connectors comprises at least three connectors spaced longitudinally from one another along each of the first and second sides.

19. 1. An offshore fluid cargo handling facility comprising: an offshore platform for handling fluid cargo; a floating storage vessel multi-point moored adjacent to the offshore platform by a plurality of multi-point mooring lines, the floating storage vessel comprising a hull extending along a longitudinal axis, the hull having a bow end and a stern end, with elongate extensions projecting from the hull at each of the bow end and the stern end parallel to the longitudinal axis, each elongate extension having a first elongate side and a second elongate side and with at least three linkages longitudinally spaced apart from one another along each elongate side, one of the plurality of multi-point mooring lines attached to each linkage; one or more airborne fluid cargo hoses extending between the offshore platform and the floating storage vessel; a fluid cargo vessel having a bow end and a stern end, the fluid cargo vessel being moored to the floating storage vessel such that the bow end and the stern end of the fluid cargo vessel are spaced apart from the multi-point mooring lines of the floating storage vessel; 1. An offshore fluid cargo handling facility comprising:

Images