CN111448353A

CN111448353A - Method for assembling an apparatus placed in a body of water

Info

Publication number: CN111448353A
Application number: CN201880018685.9A
Authority: CN
Inventors: L·费龙; E·吕基奥; P·韦伯
Original assignee: Technip France SAS
Current assignee: Technip Energies France SAS
Priority date: 2017-02-02
Filing date: 2018-01-30
Publication date: 2020-07-24
Anticipated expiration: 2038-01-30
Also published as: MY202399A; FR3062407A1; BR112019015892A2; NO20190944A1; FR3062407B1; SG11201907136WA; WO2018141725A1; KR20190111972A; KR102503139B1; CN111448353B

Abstract

The invention relates to a method comprising the following steps: providing a base (14) comprising an upper surface (22) and a mounting portion (16) protruding above the upper surface (22); assembling a guide rail (36) to the mounting portion (16); placing a module (18) for mounting on the base (14) on an upper surface located beside the base (14); translating the module (18) on the guide (36) to bring the module onto the base (14); placing the module (18) on the mounting portion (16) such that the mounting portion (16) supports the weight of the module (18); -releasing the guide rail (36) relative to the mounting portion (16); removing the guide rail (36) by horizontal movement relative to the upper surface (22) of the base (14).

Description

Method for assembling an apparatus placed in a body of water

Technical Field

The invention relates to a method for assembling an apparatus intended to be placed in a body of water, the apparatus comprising a base and at least one module placed on the base.

Background

The plant is for example a Floating Production Storage and Offloading (FPSO) unit, a floating liquefied natural gas (F L NG) unit or more generally an offshore unit such as a semi-submersible platform (which may for example be a tension leg platform (T L P)), an offloading buoy, a floating vertical column or a vessel.

Floating units of the above type typically comprise a floating hull carrying a large number of equipment devices connected to each other. The equipment devices are connected to each other, for example, by pipes, functional lines (e.g., electrical lines, hydraulic transmission lines, and/or information transmission lines).

In order to manufacture such units, it is known to assemble a hull and to arrange the different modules, which are prefabricated separately, on the hull. Once arranged on the hull, the modules are interconnected with each other so as to create different mounting systems.

The modules are typically arranged on the hull using a crane. In view of the hoisting capacity of existing cranes, this involves limitations regarding the size and weight of the modules.

Thus, a complete fluid production system sometimes needs to be divided into several modules, which must be connected and tested after assembly on the hull. This solution is therefore not satisfactory, since access to each module is more complicated than on land, and any defects in respect of the module delay the assembly of other systems and/or the commissioning of the device.

Furthermore, it is known to load modules on a floating base in some cases without the use of a crane. The floating base is ballasted to be flush with an upper surface of the dock in which the module is disposed. The module is then transferred to the base by sliding it onto guides permanently mounted on the floating base.

When the module rests on the guides, the module is fixed here on the base, which guides remain in place.

The last method means that the water depth opposite the dock is sufficient to allow the above-mentioned flushing after ballasting. The latter approach is not entirely satisfactory, including in the scenario. In fact, the presence of permanent guides on the base makes the apparatus unnecessarily heavier and takes up a lot of space on the hull, limiting the number and/or size of equipment items that can be placed on the deck of the hull.

Disclosure of Invention

It is therefore an object of the present invention to provide a method for assembling an apparatus comprising a base and at least one module placed on the base, which method does not require a crane with high hoisting capacity, while the method is carried out by means of non-invasive facilities on the apparatus.

To this end, the invention relates to a method of the aforementioned type, characterized by the following steps:

-providing a base comprising an upper surface and a protruding mounting portion above the upper surface;

-assembling the guide rail on the mounting part;

-placing a module for mounting on a base on an upper surface located beside the base;

-translating the module on the guide rail to bring the module onto the base;

-placing the module on the mounting part such that the mounting part supports the weight of the module;

-releasing the guide rail relative to the mounting part;

-removing the guide rail by horizontal movement face to face with the base upper surface.

The method according to the invention may comprise one or more of the following features, considered alone or according to any technically possible combination:

-prior to the translating step, lifting the module with a lifting structure through the lower surface of the module, so that the lower surface reaches the height of the guide rail, the lifting structure being located between the upper surface and the lower surface of the module;

-the hoisting structure comprises a hoisting beam located below the lower surface of the module, the method comprising the step of connecting the hoisting beam to the guide rail by means of a connecting beam when the lower surface is at the height of the guide rail;

-the removing step for removing the guide rails comprises pulling each guide rail horizontally from the outside of the base;

-each guide rail comprises a plurality of consecutive segments, the removing step comprising pulling at least one segment of each guide rail horizontally outside the base and then disassembling the segment located outside the base;

-the removing step comprises moving the guide rail horizontally away from the module while keeping a portion of the guide rail opposite the upper surface area located separate from the module, translating the additional module on the guide rail to the upper surface area located separate from the module, and then placing the additional module on the mounting part;

-the base bears on the upper surface the means of the equipment, above which the assembled guide rail is positioned, the means of the equipment advantageously comprising a bent of functional pipelines and/or conduits, over which the guide rail passes;

-the guide rail has an upwardly open U-shaped cross-section;

-the base has a longitudinal axis, the guide rail being assembled transversely with respect to the longitudinal axis;

-the guide rail extends over substantially the entire width of the base, the width of the module being greater than 90% of the base width, as considered at the guide rail;

-the base has a longitudinal axis, the guide rail being assembled parallel to the longitudinal axis;

-the base is partially submerged in a water mass (water mass) along the dock, the modules being carried by the dock in the placing step;

-the base comprises a hull floating on the water mass during the module translation step;

-during the module translation step, the base is placed on the bottom of a water mass or on the floor of a dry dock, the method next comprising floating the base by de-ballasting of the base and/or by filling the dry dock to float the apparatus comprising the base and the module placed on the base;

-the mass of at least one module is greater than 3500 tons;

-the lifting step comprises progressively assembling the removable structure to lift the module below the lower surface of the module;

-the base comprises at least two hulls, the at least one module being placed under the two hulls of the base after the module translation step;

-during the module translating step, each hull floats on the body of water;

-the two hulls extend in two substantially parallel directions;

-the device comprises a connecting element between the two hulls.

The invention also relates to a hydrocarbon extraction apparatus for placement in a body of water, the hydrocarbon extraction apparatus comprising a base and at least one module, the base comprising an upper surface and a mounting portion projecting above the upper surface, the base comprising two hulls which extend in substantially parallel directions, characterised in that the module is placed on the two hulls, the mounting portion supporting the weight of the module.

Drawings

The invention will be better understood by reading the following description, provided by way of example only and with reference to the accompanying drawings, in which:

figure 1 is a front view of the base of a first device manufactured using the method according to the invention;

-figure 2 is a top view of the apparatus of figure 1;

figure 3 is a front view of an assembly unit for implementing the method according to the invention;

-figure 4 is a top view of the assembly unit of figure 3;

figures 5 to 9 show successive steps of carrying out a first method according to the invention;

-figure 10 is a top view showing the position of the guide rails before placing the module on the base of the apparatus;

figure 11 is a partial cross-sectional view of the apparatus before removal of the guide rail;

figure 12 shows a mounting part mounted on the base for carrying the guide rail, the module being carried after placement;

figures 13 and 14 are top views illustrating the steps of assembling the second device using the method according to the invention;

figure 15 is a schematic view of a column of a hoisting structure used in the method according to the invention;

-figure 16 is a schematic top view of the column of figure 15;

fig. 17 is a perspective view of a second device manufactured using the method according to the invention;

fig. 18 is a perspective view of the second device of fig. 17 comprising a module;

-figure 19 is a front view of the second device of figure 18.

Detailed Description

Fig. 1 and 2 schematically show a first apparatus 10 intended to be placed in a body of water 12.

The apparatus 10 is particularly useful for the production of fluids, particularly hydrocarbons such as oil and/or natural gas, which are collected at the bottom of a body of water 12 and elevated to the surface of the body of water 12.

The plant 10 is, for example, a Floating Production Storage and Offloading (FPSO) unit or a floating liquefied natural gas (F L NG) unit, a semi-submersible platform (which may be, for example, a tension leg platform (T L P)), an offloading buoy, a floating vertical column or a vessel in one variation, the plant 10 is a fixed rigid structure of the "gravity-fed" type, such as a "gravity-based structure" (GBS).

The body of water 12 is, for example, a lake, ocean or ocean. The depth of the body of water 12 at the apparatus 10 is for example between 50m and 3000m, or even 4000 m.

Referring to fig. 1, the apparatus 10 includes a base 14 partially submerged in a body of water, the base 14 having a mounting portion 16. The apparatus 10 includes at least one module 18, the module 18 being positioned and secured on the mounting portion 16 of the base 14.

In the example shown in fig. 1 and 2, the base 14 extends along a longitudinal axis a-a' between the upstream edge 13 and the downstream edge 15. It defines a port side edge 17 and a starboard side edge 19.

The base includes a hull 20 floating in the body of water 12. The base 14 also has means forming an upper surface 22 of the deck and equipment 24 carried by the upper surface 22.

The base 14 includes a selective ballast system 26 that enables the height of the upper surface 22 relative to the surface of the body of water 12 to be adjusted by the selective ballast system 26 and enables the upper surface 22 to remain substantially horizontal even when the load imposed on the upper surface 22 is uneven and not related to tidal variations.

The components of the equipment 24 comprise, for example, functional systems such as mechanical equipment (pumps, bridge cranes, monorail, trolleys). The components of the equipment 24 also include fluid carrying conduits or functional lines (such as power, hydraulic fluid and/or information carrying lines).

In the example shown in fig. 1, 2 and 11, the equipment 24 comprises at least one longitudinal bent 27, said longitudinal bent 27 extending along the base 14 and passing under each module 18.

The bent 27 houses a plurality of fluid ducts and/or functional lines intended to connect the modules 18 to each other or to connect the modules 18 to the equipment of the equipment located on the base 14.

The mounting portion 16 projects above the upper surface 22. The height of the mounting portion 16 relative to the upper surface 22 is greater than the height of the components of the equipment 24 present on the upper surface 22.

Referring to fig. 12, each mounting portion 16 includes a base 30 and a head 32 for assembling the module 18, the head being capable of supporting the module 18. In the example shown in fig. 12, each mounting portion 16 also includes an arm 34 for carrying a guide rail 36 for guiding the module 18 during placement of the module.

The base 30 here has an upwardly converging polyhedral or frustoconical shape.

The head 32 has an upper support plate 38 for the module 18 and advantageously has an insertion channel 40 for a support device 41 of the module 18 placed on the upper support plate 38.

Each arm 34 projects laterally with respect to the base 30. In the example shown in fig. 12, the mounting portion 16 is provided with two side arms 34 extending on both sides of the base portion 30.

Each arm 34 is removable, for example, relative to the base 30 to minimize bulk on the apparatus 10 once the module 18 is installed.

In the example shown in fig. 2, the apparatus 10 comprises a plurality of modules 18 arranged in an adjacent manner along the axis a-a'.

In this example, the at least one module 18 extends over substantially the entire width of the base 14, for example over more than 90% of the width of the base 14, which is considered to be between the port side edge 17 and the starboard side edge 19.

Each module 18 includes a plurality of pre-assembled, outfitted components prior to mounting the module 18 on the base 14. Such equipment devices are for example tanks, reactors, compressors, turbines, columns similar to the system heads described above. Modules 18 are each capable of performing at least one function in assembly 10, such as separating natural gas, water, oil, and liquefied natural gas.

At least one module 18 has a mass greater than 3500 tons, preventing the module 18 from being placed by a crane having the normal hoisting capacity of the industry associated with the present invention.

As shown in fig. 11, each module 18 has a lower surface 50, the lower surface 50 being for placement against the upper surface 22 of the base 14 and for support on the mounting portion 16. Each module 18 also comprises a plurality of spacer blocks 52 projecting downwards with respect to the lower surface 50 and resting on the supporting devices 41 placed on the plate 38. Each spacer block 52 is advantageously horizontal.

The assembly method according to the invention is implemented using a placement unit 60 as schematically shown in fig. 3.

Placement unit 60 includes a production site 62 for assembling modules 18 and a loading dock 64 located between production site 62 and a water mass 66 of receiving base 14. The water mass 66 is connected to the body of water 12 to allow the apparatus 10 to be transported to the body of water 12 by flotation.

The placing unit 60 further includes: a removable lifting structure 68 for lifting the module 18 via the module lower surface 50; a rail 36, the rail 36 for placement over the base 14; a connecting beam 70, said connecting beam 70 being located between the lifting structure 68 and the guide rail 36.

Referring to fig. 7 to 9, the placing unit 60 further includes: a plurality of pads 72 for moving the modules 18 horizontally on the lifting beams 76, the connecting beams 70 and the guide rails 36; and a pulling system 74 for pulling the rail 36 away from the base 14.

As shown in fig. 3, the removable lifting structure 68 is a vehicle lift capable of lifting the lower surface 50 of the module 18 between a low position at the upper surface 75 of the dock 64 and a high position in which the module 18 is positioned above and spaced from the edge of the dock 64 without the use of a crane above the module 18.

The removable lifting structure 68 includes: a lifting beam 76 carrying the module 18, the posts 78 carrying the lifting beam 76 if there are deployable posts 78 of progressively increasing height during assembly of the module; and jacks 79 and 81 for gradually lifting each column 78 (visible in fig. 15 and 16).

In one exemplary embodiment, as shown in FIG. 15, each post 78 is formed by a series of pairs of rods 80 and pairs of cross beams 82, each pair of rods 80 being positioned perpendicular to and carrying a pair of cross beams 82.

Jacks

79, 81 are located at the base of the column 78. At least two jacks 79 are able to lift the rod 80 so that the cross beam 82 can be inserted below the rod 80.

At least two jacks 81 are able to lift the cross beam 82, making it possible to insert the rod 82 below the cross beam 80. Thus, each column 78 is assembled step-by-step in stages to gradually lift the lifting beam 76 and module 18.

Crossed diagonal members 83 (visible in fig. 3) connect the columns 78 to each other to avoid lateral instability of the assembly under the weight of the modules 18 and to tension the columns.

In the example shown in fig. 3-10, the rails 36 can extend laterally across the entire width of the base 14. Here, each guide rail 36 is made in one piece. As shown in fig. 10, the placing unit 60 includes a plurality of parallel guide rails 36, here, a pair of guide rails 36, then three guide rails 36, and thereafter another pair of guide rails 36.

Each guide rail 36 is carried by a side arm 34 of the continuous mounting portion 16. Each guide rail 36 is hollow here and has an upwardly open U-shape. It defines a central slot 84 for sliding movement of the pad 72. The slots 84 reduce the volume in the height direction of the guide rails 36 and do not alter the existing equipment 24 components and the bent 27.

In addition, the slot 84 defines two vertical walls that reinforce the bottom of the rail 36. This limits the bending of the guide rail 36 between two mounting portions 16, especially when the mounting portions 16 are separated by a distance greater than 10 meters. This allows the rail 36 to be relatively thin to reduce rail bulk.

The central slot 84 is advantageously provided with: lubricious coatings, such as those made from polytetrafluoroethylene; internal stops (not shown) that are longitudinally spaced to allow the pad 72 to be captured and pushed or pulled.

In fig. 7 and 8, each pad 72 includes a base plate 86, a jack 88 for lifting the module 18 and carried by the base plate 86, and a deployable arm 90 for pushing/pulling the base plate 86, the arm 90 being able to grasp an internal stop in the rail 36 to push/pull the base plate 86 and to move the jack 88 and the module 18 longitudinally.

Each rail 36 is removably secured to a successive mounting portion 16. When the rail 36 is released from the mounting portion 16, the rail can be pulled generally horizontally parallel to the upper surface 22 for removal from the apparatus 10.

Referring to fig. 9, a pulling system 74 can pull each rail 36 horizontally to laterally separate it from the base 14 and module 18 to free the intermediate space between the module 18 and the upper surface 22. After the module 18 has been transferred to the base 14, the pulling system 74 is fixed, for example, to the lifting structure 68. It comprises for example at least one winch.

A first method of assembly of the device 10 according to the invention will now be described.

Initially, each module 18 is assembled at the job site 62 independently of the base 14. Base 14 is brought into a water mass 66 near dock 64 and moored to dock 64 as shown in fig. 4

The rail 36 is mounted on the mounting portion 16 using a crane guide. The guide rails 36 are placed on the arms 34 of successive mounts 16.

In this example, they extend laterally across the entire width of the base 14 between the port side edge 17 and the starboard side edge 19.

The lift structure 68 occupies a low position in which the deployable posts 78 are detached and the lift beams 76 are positioned at the upper surface 75 of the dock 64.

A moving pad 72 is mounted below the lower surface 50 of the module 18. The jacks 88 of the moving pad 72 are then deployed to release the module 18 from its build post. The arm 90 is then used to activate the moving pad 72 to translate the module 18 to bring the module onto the lifting beam 76.

When the module 18 is placed on the lifting beam 76, the lifting structure 68 is switched to its high position to bring the lifting beam 76 to the same level as the guide rails 36.

In this example, the deployable post 78 is progressively assembled from the upper surface 75 to lift the lifting beam 76 and module 18 away from the upper surface 75.

In the example shown in fig. 15 and 16, the jacks 81 are first actuated to lift two crossbeams 82 located below the lifting beams 76 by a height substantially equal to the height of the bars 80. The rod 80 is placed perpendicular to the cross beam 82 and above the jack 79 of the rigid support 83B. If desired, a rigid support 83B located directly below the rod 80 can place the unit back onto the rod 80.

The jacks 81 are then retracted, the beam 82 is supported on the rods 80, and the jacks 79 are deployed to a height substantially equal to that of the beam 82.

The cross beam 82 is then placed over the jacks 81 and rigid supports 83A perpendicular to the rods 80. A rigid support 83A located directly below the cross beam 82 makes it possible to put the unit back on the cross beam 82 when required.

These operations are repeated until the lift beam 76 reaches a height equal to the height of the guide rails 36 on the base 14.

Next, as shown in fig. 4, the connecting beam 70 is inserted into the intermediate space between the lifting structure 68 and the base 14 placed in the water mass 66. Each connecting beam 70 connects the lifting beam 76 to a guide rail 36.

Once this is done, the pads 72 are actuated to translate the module 18 horizontally on the rails 36 from the lifting structure 68 toward the base 14.

In the example shown in the figures, the arm 90 of each pad 72 is spread away from the floor 86 in a direction from the dock 64 toward the base 14 to remain on the stop. The arm 90 is then retracted into the base plate 86, causing the base plate 86 to slide toward the stop and the module 18 to move along the axis defined by each rail 36.

The selective ballast system 26 is actuated to maintain the base 14 at a constant level relative to the dock 64 during advancement of the module 18, thereby maintaining alignment of each rail 36 with the connecting beam 70 and the lift beam 76. This condition must be ensured regardless of the tidal level causing the base 14 to rise or fall and the position of the module 18 during transfer of the module 18 to the base 14.

Jack 88 is in the actuated state and lower surface 50 of module 18 remains above all of the features of equipment 24 present on upper surface 22. Further, the spacer blocks 52 pass over the mounting portion 30 without abutting against the mounting portion 30.

When the module 18 reaches the desired position, for example extending the width of the base 14 from the port side edge 17 towards the starboard side edge 19, and the spacer block 52 is positioned opposite the mount 16, the jacks 88 are deactivated to access the lower surface 52 of the upper support plate 38 of the mount 16 via the support apparatus (if applicable).

During this movement, the mounting portion 16 gradually supports the weight of the module 18.

The pulling system 74 of the rails 36 is then actuated from outside the base 14 to slide the rails 36 (containing the pads 72) horizontally under the lower surface 50 and move them away from the base 14, advantageously on the lifting structure 68. Prior to this, the connecting beams 70 are removed and the ballast 26 of the hull 20 is actuated to flatten the bottom of the guide rails 36 against the top of the lifting beams 76.

The intermediate space between the module 18 and the upper surface 22 of the base 14 is released from the guide rails 36, which eliminates unnecessary weight of the apparatus 10 and increases the available space in the apparatus 10.

The assembly of the module 18 using the method according to the invention is therefore particularly simple and versatile, since it does not require a crane of high lifting capacity. Thus, even if the worksite 62 does not have a crane of sufficient lifting capacity to lift an excessively heavy module 18, a module 18 that is prefabricated and pre-tested on the worksite 62 can be assembled on the foundation 14 located in the water mass 66.

Since the guide rails 36 are arranged above the components of the equipment 24 present on the base 14, the modules 18 can be swept over the entire width of the base 14 during their installation, which makes it possible to build very wide modules 18 and shorten the installation time if applicable.

Since the rails 36 are removable, they do not add weight to the apparatus 10 once assembly is complete, and the rails 36 can be used again to place another module 18 or to assemble another apparatus 10.

In the variant shown in fig. 13 and 14, each guide rail 36 consists of several consecutive segments 100 assembled end to end. The length of each segment 100 is advantageously greater than or equal to the length of the module 18.

In this example, the guide rails 36 are placed parallel to the longitudinal axis of the base 14. The upstream edge 13 of the base 14 is opposite the dock 64.

During assembly of the apparatus 10, the first module 18 translates on the rails 36, as previously described, until its resting position is reached. The module 18 is then placed on the mounting portion 16 by lowering the jacks 88.

Next, the segment 100 of the rail 36 located below the module 18 is removed by horizontal translation below the module 18 using the pulling system 74. The section 100 of the guide rail 36 that has been removed from the base 14 is separated from the section 100 that remains on the base 14, as shown in fig. 14.

At least one segment 102 of each rail 36 remains positioned across from the area of upper surface 22 adjacent to module 18. The additional module 18 is then translated on the guide 36 until the area of the upper surface 22 that is positioned away from the module 18. An additional module 18 is placed on the mounting portion 16.

The rail section 102 located below the additional module 18 is then removed horizontally as described above.

In a variant, during the step for translating the module 18, the base 14 is placed on the bottom of the water mass 66 or in the dry dock 67 (see fig. 13). The method next includes the step of floating the base 14 by de-ballasting and/or filling the dry dock 67.

Fig. 17 to 19 show a second device 110 according to the invention.

The second apparatus 110 differs from the first apparatus 10 in that the base 14 comprises two hulls 20.

In this example, the second apparatus 110 further includes a turntable mounting portion 92, a turntable 93, and a connecting member 94.

The two hulls 20 extend in substantially parallel directions parallel to the axis a-a' of the base 14.

Advantageously, the two hulls 20 are substantially equal in size.

The two hulls 20 advantageously house the components of the pre-assembled rig 24 as defined above.

Advantageously, each hull 20 houses a device of equipment 24 as defined above, preassembled, having a different function than the device of equipment 24 comprised in the other hull 20.

For example, the first hull 20 is equipped to store liquefied natural gas, while the second hull 20 is equipped to store condensate from the gas (light oil) or any liquid or solid associated with the process.

At least one module 18 is configured to be placed on the two hulls 20 of the base 14 to transversely connect the two hulls 201, as shown in fig. 18 and 19.

In particular, at least one module 18 is placed orthogonally with respect to the axis a-a' on both hulls 20.

Thus, the connection between the two hulls 20 to form the base 14 is provided by at least one module 18. There is no need to use closed boxes or coupling beams between the hulls 20, thus avoiding complicated installations inside or outside the dry dock.

The turntable mount 92 is connected to the two hulls 20. In particular, the turret mount 92 is connected to an end along the axis a-a' of each hull 20, for example to the bow.

The turntable mounting portion 92 is assembled so as to rotate around the turntable 93. The turret 93 is secured to the bottom of the body of water by anchor lines to allow anchoring of the apparatus 110.

As shown in fig. 18 and 19, the connecting element 94 is located between the two hulls 20.

The connecting element 94 advantageously extends along the axis a-a' and is connected to the upper edge of each hull 20.

The connecting member 94 enhances the horizontal rigidity of the device 110.

The connecting elements 94 provide access between the decks of the two hulls 20 for personnel of the equipment 110 to access the components of the equipment 24.

A second method of assembly of the second device 110 will now be described.

The second assembly method is similar to the first assembly method.

The second method of assembly differs from the first assembly means in that the two hulls 20 are formed separately and then sent to the same assembly work site 62. With the two hulls 20 side by side and floating.

The hulls 20 are provided with mounts 16, the mounts 16 being positioned to project above the upper surface of each hull 20.

The connecting element 94 is mounted between the two hulls 20, making it possible to keep each hull 20 at a fixed horizontal distance from each other. In a variant, the connecting element 94 is mounted in the dry dock.

The guide rails 36 are then assembled transversely on the mounting 16, the guide rails 36 overlying the intermediate spaces between the hulls 20 being held constant by the horizontal connecting elements 94. In a variant, the guide rails 36 serve as a temporary connection between the two hulls 20, without the need for horizontal connecting elements 94.

Next, the module 18 is placed on the upper surface 75 and translated on the track 36 until at least a first region of the module 18 extends across the mount 16 of the first hull 20 and a second region of the module 18 extends across the mount 16 of the second hull 20. The middle region of the module 18 then extends across the intermediate space between the hulls 20. The module 18 is then placed on the mount 16 of each hull 20. The guide rails 36 are then released and removed as described above. The mount 16 then supports the weight of the module 18 and the connecting force of the two hulls 20.

During the steps for translating the module 18 and placing the module on the mount 16, each hull 20 floats on a water mass 66.

In a variant, the two modules 18 are installed in the dry dock in the same way as before.

Thus, the second apparatus 110 allows for reduced construction time and cost, as it allows for the separate construction of two hulls 20 by a builder who does not have a large dry dock of sufficient size to accommodate two hulls positioned in parallel or a heavy lift crane.

The assembly of the base 14 is easily accomplished at the workplace 62 or at the water mass 66. Furthermore, the stability of the base 14 and its seaworthiness are improved due to the two modules 18 being placed parallel to each other.

Claims

1. A method for assembling an apparatus (10) for placement in a body of water (12), the apparatus (10) comprising a base (14) and at least one module (18) placed on the base (14), the method characterized by the steps of:

-providing a base (14) comprising an upper surface (22) and a mounting portion (16) protruding above the upper surface (22);

-assembling a guide rail (36) on the mounting part (16);

-placing said module (18) for mounting on said base (14) on an upper surface (75) located beside said base (14);

-translating the module (18) on the guide rail (36) to bring it onto the base (14);

-placing the module (18) on the mounting portion (16) such that the mounting portion (16) supports the weight of the module (18);

-releasing the guide rail (36) relative to the mounting part (16);

-removing the guide rail (36) by horizontal movement in face to face with the upper surface (22) of the base (14).

2. The method of claim 1, the method comprising: -lifting the module (18) by its lower surface (50) before the translating step, using a lifting structure (68) positioned to bear between the upper surface (75) and the lower surface (50) of the module (18), bringing the lower surface (50) to the level of the guide rail (36).

3. Method according to claim 2, wherein the lifting structure (68) comprises a lifting beam (76) placed below the lower surface (50) of the module (18), the method comprising the steps of: -connecting the lifting beam (76) to the guide rail (36) by means of a connecting beam (70) when the lower surface (50) is at the height of the guide rail (36).

4. The method according to any one of the preceding claims, wherein the removing step of removing the guide rail (36) comprises: pulling each of the rails (36) horizontally from outside the base (14).

5. The method of claim 4, wherein each of the guide rails (36) includes a plurality of continuous segments (100), the removing step including: pulling horizontally at least one segment of each of the rails (36) from outside the base (14) and then removing the segment (100) located outside the base (14).

6. The method of any one of the preceding claims, wherein the removing step comprises: horizontally moving the rail (36) away from the module (18) while maintaining a portion of the rail (36) positioned across from a region of the upper surface (22) spaced from the module (18); -translating an additional module (18) on the guide rail (36) to the area of the upper surface (22) positioned apart from the module (18), and then placing the additional module (18) on the mounting portion (16).

7. Method according to any one of the preceding claims, wherein the base (14) carries means of an equipment (24) on the upper surface (22), the guide rails (36) being positioned above the equipment (24) after assembly, the means of the equipment (24) advantageously comprising a bent (27) of functional lines and/or ducts, the guide rails (36) passing above the bent (27).

8. The method of claim 7, wherein the guide rail (36) has an upwardly open U-shaped cross section.

9. Method according to any one of the preceding claims, wherein the base (14) has a longitudinal axis (a-a '), the guide rail (36) being assembled transversely with respect to the longitudinal axis (a-a').

10. Method according to claim 9, wherein the rail (36) extends substantially over the entire width of the base (14), the width of the module (18) being greater than 90% of the width of the base (14) when considered at the rail (36).

11. Method according to any one of claims 1 to 8, wherein the base (14) has a longitudinal axis (A-A '), the guide rail (36) being assembled parallel to the longitudinal axis (A-A').

12. A method according to any preceding claim, wherein the base (14) is partially submerged in a water mass (66) along a dock (64), the module (18) being carried by the dock (64) during the placing step.

13. The method of claim 12, wherein the base (14) includes a hull (20), the hull (20) floating on the water mass (66) during the step of translating the module (18).

14. Method according to any one of claims 1 to 12, wherein during the step of translating the module (18), the base (14) is placed on the bottom of the water mass (66) or on the floor of a dry dock (67), the method comprising next: -floating the base (14) by de-ballasting the base and/or by filling the dry dock (67) to float an apparatus (10) comprising the base (14) and the module (18) placed on the base (14).

15. The method according to any one of the preceding claims, wherein the base (14) comprises at least two hulls (20), at least one module (18) being placed under the two hulls (20) of the base (14) after the module (18) translation step.

16. The method of claim 15 wherein each of the hulls (20) floats on the water mass (66) during the module (18) translating step.

17. A method according to any of claims 15 or 16, wherein the two hulls (20) extend in two substantially parallel directions.

18. A method according to any one of claims 15 to 17, wherein the apparatus (110) comprises a connecting element (94) between the two hulls (20).

19. A hydrocarbon production apparatus (110) for placement in a body of water (12), the hydrocarbon production apparatus comprising a foundation (14) and at least one module (18), the foundation (14) comprising an upper surface (22) and a mount projecting above the upper surface (22), the base (14) comprising two hulls (20) advantageously extending in substantially parallel directions, characterised in that the module (18) is placed on the two hulls (20), the mount (16) supporting the weight of the module (18) and the connecting force of the two hulls (20).