NO20131180A1 - Moonpool in downtown - Google Patents

Description

MOONPOOL IN THE CENTRE

TECHNICAL AREA

The present report relates to a partially submersible unit for use in offshore applications. The explanation is further related to a procedure for moving an object, e.g. a well intervention device, in relation to a partially submersible unit.

BACKGROUND

Partially submersible devices, such as platforms or rigs, are widely used in marine applications. Partially submersible production units and partially submersible drilling rigs are generally known and are largely used e.g. during drilling for or production of natural resources such as hydrocarbons, e.g. gas, oil etc. Common to all is that they provide stable structures that are designed to be partially submersible in the water, whereby a raft, such as one or more pontoons, provides buoyancy. Their draft level can be adjusted and controlled depending on the situation.

As part of various operations performed on the unit, an object, such as a piece of equipment, may be launched from the unit's deck structure into the surrounding water or raised from the surrounding water to the deck structure. It is known to carry out such operations on the outboard side of the deck structure and the raft. However, there is a risk that the object will be damaged, e.g. when it passes the spray zone, especially in harsh weather conditions, e.g. that the object is damaged by waves and/or is thrown against the partially submersible unit.

Document WO 2005/056380 A1 shows a partially submersible unit for use in offshore applications. The unit comprises a hull configuration including vertical support columns, a central pontoon structure arranged inboard of the columns at a lower end thereof, and a deck structure supported at an upper portion of the columns. The vertical columns are adjacent to the outer periphery of the central pontoon and have a transverse cross-sectional shape with a major axis oriented radially outward from a center point of the hull, and a central vertical axis arranged at a distance outward from the outer periphery of the pontoon. In one embodiment, the central pontoon structure is located inboard of the vertical columns and may have a central moonpole opening.

However, when an object is launched from the unit deck structure described in WO 2005/056380 A1 downward towards the pontoon structure and possibly through the pontoon structure's central moonpool opening, or moved in the opposite direction, the object is unprotected as it passes the water level. There is then a risk of the object being damaged, e.g. when it passes the spray zone, especially in harsh weather conditions, e.g. the object is damaged by the waves.

SUMMARY

The purpose of the present disclosure is to overcome or to improve at least one of the disadvantages of the known technique, or to provide a useful alternative.

It is desirable to provide a partially submersible unit which is able to reduce, or preferably avoid, the risk of damaging objects launched from the unit or raised up to the unit, especially objects such as well intervention equipment.

The purpose above can be achieved by the content of claim 1.

Therefore, there is provided in a first aspect of the present disclosure a partially submersible unit for use in offshore applications comprising a raft located below a still water level, a deck structure located above the still water level and at least two support columns connecting the raft and the deck structure such that still the water level crosses the support columns. The unit further comprises an object-moving set-up adapted to assist in the movement of an object. The object moving setup is at least partially located between the deck structure and the raft. The object-moving set-up includes a guide set-up to guide the object during movement. The object-moving set-up is fixedly connected in at least one lateral direction to at least one of the support columns and/or to the raft.

The partially submersible unit comprises a deck structure which may comprise a plurality of different decks located at different levels. On the various decks, equipment used in relation to hydrocarbon drilling and production operations may be provided, as is customary in the area. Also areas such as accommodation areas and control rooms can be provided on the deck structure. The unit also includes a raft, e.g. one or more pontoons, usually completely submerged in the water at a distance below the still water level. The float provides buoyancy that keeps the device partially submerged in the water. The unit further comprises two or more support columns which connect the deck structure to the raft, e.g. four support columns, one in each corner of the unit. The still water level will cross each column during normal operation of the unit. One or more of the columns may also provide buoyancy.

The term "quiet water level" is often used in the area and can be defined as an average water surface elevation at any time, excluding local variation due to waves and wave formations, but including the effects of tides, storm waves and long period seiches.

The object moving setup can have two functions. First, it can protect the object during moving. For the others, it can guide the object during movement using the guidance layout.

The guide setup is used to guide the object during movement, preferably at least as it passes the spray zone.

The object moving setup is at least partially located between the deck structure and the raft. The object moving assembly and/or guide assembly may be arranged to extend downwardly from the deck structure. A part of the object-moving setup and/or the guiding setup can extend over the deck structure. The object moving setup and/or guide setup may extend down to the raft or even past the raft. The object moving setup and/or guide setup preferably extends through the splash zone so that it can protect the object being launched or raised at least when it passes the splash zone. The object-moving set-up and/or guide set-up preferably does not go all the way to the seabed. Separately, the object-moving set-up and/or guide set-up is not a riser that goes all the way to the seabed. The object-moving set-up and/or the guide set-up can, for example, end a maximum of 10 meters below a base line of the fleet.

The object moving setup and/or guide setup can have a vertical position that is adjustable in relation to the rest of the unit. Thus, the vertical position of the object moving setup can be adjusted when the unit's draft level changes. Furthermore, the object-moving set-up and the guide set-up are preferably located inboard of the support columns.

The object moving assembly is preferably permanently attached to the rest of the partially submersible unit.

The deck structure of the partially submersible unit may include an opening. In that case, the object-moving setup is preferably adapted to the opening so that an object launched through the opening can move downwards through the object-moving setup towards the surrounding water.

The object-moving setup can be fixedly attached to at least one of the support columns and/or to the raft by means of a support structure. The support structure connects the object-moving set-up in at least a lateral direction. The support structure can connect the object-moving setup in one direction, i.e. a one-dimensional connection such as by means of a wire or a chain. A one-dimensional link can be used to prevent the object moving layout from moving further away from the structure to which it is linked. Alternatively, the support structure can connect the object-moving setup in a plane, e.g. a horizontal plane, i.e. a two-dimensional connection, such as by means of a plurality of wires and chains extending in different directions. As a further alternative, the support structure may connect the object moving setup with a three-dimensional link, such as by means of a support pontoon or a lateral support framework, as described below, which extends into the raft e.g. between the raft's pontoons, or extending from one of the raft's pontoons. Such a three-dimensional coupling is capable of limiting movements in all three dimensions, keeping the object-moving setup in a defined three-dimensional position relative to the rest of the unit.

The object to be moved by or through the object moving setup can e.g. be a well intervention device. A well intervention equipment is a piece of equipment used in a well intervention operation. The well intervention equipment can therefore be used in operations such as: inspection e.g. with a camera, perforating/re-perforating, zone isolation, inspection/repair/installation of an insertion downhole safety valve, "miling" of short-scale bridges, well killing, pumping, weight treatment, selective tracer injection or sampling, gas lift valve replacement, sleeve operations for DIACS -valves (Downhole Instrumentation And Control System valves), plugging and surrender operations of underwater wells, replacement/installation of underwater trees, data collection, e.g. production logging toolstring.

The term well intervention equipment as used herein does not include drill pipe or drill riser.

The guide assembly may be arranged to be connected to the object during movement under the deck structure. If the object is to be launched into the surrounding water, the object is preferably releasably attached to the guide setup so that the object can be released when it reaches a lower end of the object moving setup. Alternatively, or in addition, the object can be released through an opening in a side wall of the object moving setup.

In one embodiment, the object-moving set-up and/or guide set-up extends at least through a range of +/- 3 meters in relation to the still water level, i.e. from 3 meters above the still water level to 3 meters below the still water level. Preferably, the object-moving set-up and/or guide set-up extends +/-5 meters in relation to the still water level and most preferably +/-10 meters in relation to the still water level. Thus, the object is protected and guided when it passes in the relevant water level and through the splash zone. However, the object moving setup and/or guide setup preferably does not go all the way to the seabed.

The guide setup may comprise a guide track, a guide chain or a guide wire to guide the object during the move. One or more guide tracks, guide chains or guide wires can be used. They can be located on the inside of the object moving setup, e.g. on the inside of a side wall.

A guide assembly may form a separate unit which, although normally attached to the rest of the object moving assembly, is nevertheless capable of being separated from the rest of the object moving assembly, e.g. a guide rail, a guide chain or a guide rail. As an alternative, the guiding setup can be integrated into the rest of the object moving setup as an integrated unit, e.g. a wall of the object-moving set-up or a beam of a framework of the object-moving set-up forming the guide set-up.

The object-moving set-up can be mainly located centrally in relation to the deck structure. Alternatively, the object-moving set-up can be located outside the center in relation to the deck structure. However, the object-moving set-up and thus the guide set-up are preferably located inboard of the support columns. This is because relative movements in the area located inboard of the support columns are lower than the relative movements outboard of the support columns.

The object-moving setup may have a substantially circular, square, rectangular, hexagonal, octagonal or other polygonal cross-sectional shape. The object moving setup can form a cylinder or a parallelepiped.

The object-moving setup can comprise a trunk, preferably shaped like a cylinder or a rectangular parallelepiped.

The trunk may comprise a framework and/or a lattice structure. A framework or lattice structure weighs less than a solid wall.

The trunk may comprise a substantially closed side wall. This type of wall provides good protection for the object to be moved.

The object-moving setup can comprise a wall, preferably a flat wall. The wall can shape the management layout.

The guide layout can comprise a plurality of guide tracks, guide chains or led wires.

The object moving setup may comprise a frame, preferably located mainly at the level of the raft. The frame can be used for connecting a guide track, a guide chain or a guide wire.

In one embodiment, the object-moving set-up comprises the frame and a plurality of guide tracks, guide chains or guide wires, in which the plurality of guide tracks, guide chains or guide wires connect the frame to the support columns and/or to the raft in at least one lateral direction. The part of the plurality of guide tracks, guide chains or guide wires that connect the frame to the support columns and/or to the raft constitutes the support structure in that case. The majority of guide tracks, guide chains or guide wire may also be used to connect the frame to the deck structure. It would also be possible to use a plurality of guide tracks, guide chains or guide wire to connect a trunk or other type of object moving setup to the deck structure, support columns and/or raft.

The support structure may comprise a laterally extending support pontoon which extends from at least one of the support columns and/or the raft, preferably extending between at least two of the support columns and/or the raft. The support pontoon can e.g. stretch between two of the raft's pontoons. The support pontoon is an example of a three-dimensional link capable of restraining movement in all three dimensions that keeps the object-moving support setup in a defined three-dimensional position relative to the rest of the unit.

As an alternative or as a complement, the support structure may comprise a lateral support framework or a lateral support lattice structure which extends in at least one lateral direction from one or more of the support columns and/or from the raft. This is another example of a three-dimensional link capable of constraining movement in all three dimensions that keeps the object-moving setup in a defined three-dimensional position relative to the rest of the assembly.

In another aspect of the present disclosure, there is provided a method of moving an object, e.g. a well intervention device, in relation to a partially submersible unit, e.g. launch or raise the object in or from the surrounding water. The unit comprises a raft located below a still water level, a deck structure located above the still water level and at least two support columns connecting the raft and the deck structure so that the still water level crosses the support columns. The method includes moving the object by or through an object-moving setup while the object is guided using a guiding setup included in the object-moving setup. The object moving setup is at least partially located between the deck structure and the raft. The object-moving set-up is firmly attached in at least one lateral direction to at least one of the support columns and/or to the raft.

The procedure also includes connecting the control set-up to the object during relocation.

The method can also include and release the object from the guide setup when it reaches a lower end of the object moving setup.

Alternatively, or in addition, the object can be released through an opening in the side wall of the object moving setup.

BRIEF DESCRIPTION OF THE FIGURES

In the following, the present invention will be further explained using non-limiting examples with reference to the attached figures in which: Fig. 1 is a schematic view of a partially submersible floating unit seen from the side,

Fig. 2 is a top view of the partially submersible unit,

Fig. 3a is a schematic view of a partially submersible unit according to a first

embodiment of the invention seen in cross-section from the side,

Fig. 3b is a horizontal cross-section of the partially submersible unit in Fig. 3a, Fig. 4 is a schematic view of a partially submersible unit according to a second

embodiment of the statement seen in cross-section from the side,

Fig. 4b is a horizontal cross-section of the partially submersible unit in Fig. 4a, Fig. 5a is a schematic view of a partially submersible unit according to a third

embodiment of the statement seen in cross-section from the side,

Fig. 5b is a horizontal cross-section of the partially submersible unit in Fig. 5a.

It should be noted that the attached figures are not necessarily drawn to scale and that the dimensions of some of the features of the present disclosure may have been exaggerated for clarity.

DETAILED DESCRIPTION

In the following, the explanation will be exemplified by embodiments. However, it should be realized that the embodiment is included to explain the principles of the invention and not to limit the scope of the invention defined by the appended claims. Details from two or more embodiments can be combined with each other.

Figures 1 and 2 schematically illustrate a partially submersible unit 1 for use in offshore applications, for example with purposes as described above. Figure 1 illustrates the partially submersible unit 1 seen from the side and Figure 2 illustrates a top view.

The partially submersible unit 1 comprises a deck structure 2 which may comprise a plurality of different decks located at different levels. On the various decks, equipment used in relation to hydrocarbon drilling and production operations may be provided as is customary in the area. Also areas such as accommodation areas and control rooms can be provided on the deck structure. A main deck 4, often also referred to as an operations deck, is located relatively high above a calm sea level, preferably so high that the waves will not normally splash over the surface of the main deck 4. The unit 1 further comprises a raft 5, here illustrated in the form of a plurality of pontoons 6, usually completely submerged in the water at a distance below the still water level. The raft 5 provides buoyancy which keeps the unit 1 partially submerged in the water. The unit 1 comprises two or more support columns 8 which connect the deck structure 2 to the raft 5. One or more of the columns 8 can also provide buoyancy. In Figures 1 and 2, the unit 1 is illustrated to include four support columns 8, one in each corner of the unit 1. The still water level crosses each column 8 during normal operation of the unit.

The partially submersible unit 1 is further provided with a ballast system which is

known in the area. The unit's draft level can be adjusted using the ballast system. That is, the degree of submergence of the partially submersible unit can be adjusted, i.e. its crossing with the still water level can be adjusted. During transport of the unit 1, the unit 1 is usually located relatively high in the water, often with a draft level close to the upper level of the raft 5. This is usually referred to as a transit position having the draft located at a transit draft level 10. When the unit 1 is not transported, for example when used during operations such as those described above, it is lowered to an operational position. The still water level now crosses the support columns 8 at operating draft 12. The position at operating draft 12 may vary depending on the type of operation being carried out, weather conditions, structure and dimensions of the partially submersible unit, etc. In the illustrated example, the operating draft may be in the range of 10-20 meters measured from a baseline 14 of the unit, i.e. from the underside of the raft 5.

The deck structure 2 of the illustrated partially submersible unit 1 comprises the opening 15 for launching or raising equipment.

Figures 3a and 3b schematically illustrate a partially submersible unit 1 according to a first embodiment of the invention, where Figure 3a illustrates a cross-section of the partially submersible unit 1 seen from the side and Figure 3b illustrates a horizontal cross-section. Components and structures already mentioned in connection with Figures 1 and 2 will not be mentioned again.

The illustrated partially submersible unit 1 in Figures 3a and 3b comprises four support columns 8, one in each corner, but it will, according to the invention, also be possible to use three support columns, or five, six or more. The partially submersible unit comprises an object-moving setup, here in the form of a trunk 18.

The trunk 18 has a substantially square cross-section with rounded corners so that the trunk 18 is substantially shaped like a square parallelepiped. The trunk 18 comprises a substantially closed side wall 20. The trunk 18 extends downwards from the deck structure 2 down to the raft 5. The trunk 18 is adapted to the opening 16 in the deck structure 2, see Figure 2, so that an object (not illustrated) that is launched through the opening 16 can move downwards through the trunk 18. The object can e.g. be a well intervention device (not illustrated). In the illustrated example, the trunk 18 is located centrally in relation to the deck structure 2, but it would also be possible to locate it outside the centre. The object-moving setup 18 is anyway preferably located inboard of the support columns 8. The object-moving setup 18 extends at least through a range of +/- 3 meters in relation to the still water level, i.e. from three meters above the still water level to three meters below it set the water level. Preferably, the object moving setup 18 extends +/- 5 meters in relation to the still water level and most preferably +/- 10 meters in relation to the still water level. Thus, the object is protected and guided when it passes the actual water level and through the splash zone.

The trunk 18 comprises a guide setup 22 for the equipment that is launched or raised in the trunk 18. Part of the side wall 20 itself can form the guide setup 2 or there can be, optionally, a guide track, a guide chain, a guide wire or similarly located attached to the side wall 20. In the illustrated example, there are two guide tracks 24. The guide set-up 22 is arranged to be connected to the moving object under the deck structure 2 in order to guide the object safely through the object-moving set-up 18, e.g. avoid the object hitting the side wall 20. If the object is to be launched into the surrounding water, it is releasably attached to the guide setup 22 so that the object can be released from the guide setup 22 when it reaches a lower end 26 of the object moving setup 18. Alternatively, or in addition, the object can be released through an opening in the side wall 20 of the trunk 18.

A support structure 28 connects the trunk 18 to the raft 5 so that the trunk 18 is laterally supported in at least one direction. Thus, the trunk 18 is prevented from swaying laterally. In the illustrated example, the support structure comprises a laterally extending support pontoon 30. Since the object-moving set-up 18 is centrally located in relation to the deck structure 2, the support pontoon 30 is also centered. Correspondingly, if the object-moving setup 18 will be located outside the center, the support structure 28 can be located outside the center, e.g. so that the object-moving setup 18 extends mainly vertically downwards. The support pontoon 30 can be a wing pontoon as indicated in Figures 3a and 3b. The illustrated laterally extending support pontoon 30 is an example of a three-dimensional linkage capable of limiting movement in all three dimensions, holding the object-moving assembly 18 in a defined three-dimensional position relative to the rest of the assembly 1. The raft may also comprise a pair of transverse connectors 31 which connect the two pontoons 6.

The first embodiment makes it possible to guide the object through the spray zone in a protected environment inside the object moving setup 18 with a reduced influence from weather, wind and waves compared to a unit that has no object moving setup.

The object-moving set-up 18 and/or the guide set-up 22 do not all go down to the seabed. In particular, the object-moving setup 18 and/or the guide setup 22 is not a riser that goes all the way to the seabed. The object-moving set-up 18 and/or the guide set-up 22 can, for example, end at the level of the support structure 28 or around the base line 14 of the raft 5, or a maximum of 10 meters below the base line 14 of the raft 5.

Figures 4a and 4b schematically illustrate a partially submersible unit 1 according to a second embodiment of the invention, where Figure 4a illustrates a cross-section of the partially submersible unit 1 seen from the side and Figure 4b illustrates a horizontal cross-section. Components and structures already mentioned in connection with Figures 1, 2, 3a and 3b will not be mentioned again.

The second embodiment of the partially submersible unit 1 illustrated in Figures 4a and 4b comprises an object-moving setup 18', here located outside the center, compared to a location at the center of the unit as illustrated for the first embodiment, see Figures 3a and 3b. The object moving setup 18' of the second embodiment comprises a framework 32 or a latticework which gives the object moving setup 18' a general square parallelepiped shape, in the illustrated example with an open upper end adapted to the opening 16 in the deck structure 2 and an open lower end 26' located in the surrounding water. A part of the object-moving setup 18' includes a net structure 34. The spaces of the net structure 34 are smaller than those in the framework 32. The part with the net structure 34 is conveniently located where the object-moving setup 18' crosses the still water level so that the net structure 34 extends at least through a range of +/-3 meters in relation to the still water level, preferably +/- 5 meters in relation to the still water level and most preferably +/-10 meters in relation to the still water level. Guide tracks 24 are, as an alternative, attached to the framework 32 to guide the object being moved.

The object moving assembly 18' is laterally supported by a lateral support framework 36 extending from one of the pontoons 6. The illustrated lateral support framework 36 is another example of a three-dimensional linkage capable of limiting movement in all three dimensions, holding object-moving setup in a defined three-dimensional position relative to the rest of the unit 1. It will also be possible to have a lateral support framework that extends from another pontoon in addition, e.g. the opposite pontoon, especially in the event that the object moving setup 18' will instead be centrally located. It will also be possible to use a support pontoon such as the laterally extending support pontoon 30 of the first embodiment. Furthermore, the object moving setup 18 of the first embodiment may be laterally supported by a lateral support framework 36 such as that indicated in Figures 4a and 4b.

Figures 5a and 5b schematically illustrate a partially submersible unit 1 according to a third embodiment of the invention, with Figure 5a illustrating a cross-section of the partially submersible unit 1 seen from the side and Figure 5b illustrating a horizontal cross-section.

The third embodiment illustrates an object-moving setup 18" comprising a frame 28, here located approximately at the upper level of the raft 5. The frame 38 is preferably located at least below the water level, preferably at least 3 meters below the still water level, preferably at least 5 meters and most preferably at least 10 meters. The frame 28 is connected by guide wires 40 to the deck structure 2. In the illustrated example, the frame 38 is square and a guide wire 40 is connected at each corner of the frame 38 and extends to each corner of the opening 16 in the deck structure 2. Furthermore, connecting lateral support wires 42 the frame 28 to the pontoons 6. In the illustrated example, with the square frame 38, a lateral support wire 42 is connected to each corner of the frame 38 and runs to the respective pontoon 6 so that the frame 38 is held in a substantially horizontal position. the same wire can be used both as a guide wire 40 and a lateral support wire 42 as illustrated in Figures 5a and 5b. One or more of the guide the wires 40 may act as the guide setup to guide an object being moved through the object moving setup 18". The third embodiment offers a solution with low weight, but still able to guide the object being moved.

The guide wires 40 illustrated by the third embodiment can also be used for a trunk 18 such as that of the first embodiment or a framework 32 such as that of the second embodiment, especially for the case where the object moving setup 18, 18', 18" does not extend itself all the way up to the deck structure 2. In that case, the guide wires 40 can be located in the trunk 18 or the framework 32.

The lateral support wires 42 illustrated in the third embodiment may also be used to connect a trunk 18 such as that in the first embodiment or a framework 32 such as those in the second embodiment to at least one of the support columns and/or to the raft, particularly if there is a desire to save weight.

In another aspect of the invention, a method is shown for moving an object, e.g. a well intervention equipment, in relation to the partially submersible unit 1, e.g. to launch or raise the object. The method comprises moving the object by or through an object-moving setup 18, 18'. 18" while it is guided by means of a guide set-up 22, 24, 40 included in the object-moving set-up 18, 18', 18". The object-moving setup 18, 18', 18" is at least partially located between the deck structure 2 and the raft 5. The object-moving setup 18, 18', 18" is firmly attached in at least one lateral direction to at least one of the support columns 8 and/or to the raft 5 e.g. by means of a support structure 28, 30, 36, 42.

The method can further, as an option, include connecting the guide set-up 22, 24, 40 to the object being moved.

In that case, the method may include releasing the object from the guide assembly 22, 24, 40 when it reaches the lower end 26, 26' of the object moving assembly 18, 18', 18".

Further modifications of the invention within the scope of the attached claims are possible. Therefore, the present invention should not be considered as limited by the embodiment and figures described herein. Rather, the entire scope of the invention should be determined by the appended claims, with reference to the description and figures.

Claims (23)

1. A partially submersible unit (1) for use in offshore applications comprising: a raft (5) located below a still water level, a deck structure (2) located above said still water level, and at least two support columns (8) connecting said raft (5) and said deck structure (2) so that said still water level crosses said support columns (8), characterized by said unit (1) further comprises an object-moving setup (18, 18', 18") adapted to assist in moving an object, said object-moving setup (18, 18', 18") is at least partially located between said cover structure (2 ) and said fleet (5), said object-moving set-up (18, 18', 18") comprises a guide set-up (22, 24, 40) to guide said object during movement, and said object-moving set-up (18, 18', 18") is firmly connected in at least one lateral direction to at least one of said support columns (8) and/or to said raft (5). 2. The partially submersible unit (1) according to claim 1, in which said object-moving setup (18, 18', 18") is connected to said at least one of said support columns (8) and/or to said raft (5) by with the help of a support structure (28, 30, 36, 42). 3. The partially submersible unit (1) according to any one of the preceding claims, wherein said cover structure (2) comprises an opening (16), said object moving arrangement (18, 18', 18") is adapted to said opening (16). 4. The partially submersible unit (1) according to any of the preceding claims, wherein said object is a well intervention device. 5. The partially submersible unit (1) according to any one of the preceding claims, wherein said guide arrangement (22, 24, 40) is adapted to be connected to said object during movement under said deck structure (2), said object being releasably attached to said guide setup (22, 24, 40). 6. The partially submersible unit (1) according to any one of the preceding claims, wherein said object moving setup (18, 18', 18") and/or said guide setup (22, 24, 40) extends through a range of +/-3 meters in relation to said still water level, preferably +/-5 meters in relation to said still water level and most preferably +/-10 meters in relation to said still water level. 7. The partially submersible unit (1) according to any one of the preceding claims, wherein said object moving arrangement (18, 18', 18") and/or said guide arrangement (22, 24, 40) extend downwards from said tire structure (2). 8. The partially submersible unit (1) according to any of the preceding claims, wherein said object-moving setup (18, 18', 18") and/or said guide setup (822, 24, 40) extends down to or beyond said fleet (5). 9. The partially submersible unit (1) according to any one of the preceding claims, wherein said guide arrangement (22, 24, 40) comprises a guide track (24), a guide chain or a guide wire (40) to guide said object during relocation. 10. The partially submersible unit (1) according to any one of the preceding claims, wherein said object-moving setup (18, 18") is mainly located centrally in relation to said deck structure (2). 11. The partially submersible unit (1) according to any one of claims 1 to 9, wherein said object moving setup (18') is located away from the center in relation to said deck structure (2). 12. The partially submersible unit (1) according to any of the preceding claims, wherein said object-moving setup comprises a trunk (18, 18"), preferably designed as a cylinder or a rectangular parallelepiped. 13. The partially submersible unit (1) according to claim 12, wherein said trunk (18) comprises a substantially closed side wall (20). 14. The partially submersible unit (1) according to claim 12, in which said object-moving setup (18') comprises a framework (32), a lattice work and/or a lattice structure (34). 15. The partially submersible unit (1) according to any one of the preceding claims, wherein said object moving setup (18, 18', 18") comprises a wall, preferably a flat wall. 16. The partially submersible unit (1) according to any one of the preceding claims, wherein said guide arrangement (22, 24, 40) comprises a plurality of guide tracks (24), guide chains or guide wires (40). 17. The partially submersible unit (1) according to any one of the preceding claims, wherein said object-moving setup (18") comprises a frame (38), preferably mainly located at the level of said raft (5). 18. The partially submersible unit (1) according to claims 16 and 17, in which said object-moving set-up (18") comprises said frame (38) and said plurality of guide tracks, guide chains or guide wires (40), said plurality of guide tracks, guide chains or guide wires (40) connects said frame (38) to said support columns (8) and/or to said raft (5) in at least one lateral direction. 19. The partially submersible unit (1) according to any of the preceding claims, in which said object-moving setup (18, 18') is fixedly connected to said at least one of said support columns (8) and/or to said raft ( 5) by means of a laterally extending supporting pontoon (30) which extends from at least one of said support columns (8) and/or said raft (5), preferably extending between at least two of said support columns (8) and/or said fleet 85). 20. The partially submersible unit (1) according to any of the preceding claims, in which said object-moving setup (18, 18', 18") is fixedly connected to said at least one of said support columns (8) and/or to said raft (5) by means of a lateral support framework (36) or a lateral support grid structure which extends at least in a lateral direction from one or more of said support columns (8) and/or from said raft (5). 21. A procedure for moving an object in relation to a partially submersible unit (1), said unit (1) comprises: a raft (5) located below a still water level, a deck structure (2) located above said still water level, and at least two support columns (8) which connect said raft (5) and said deck structure (2) so that said still water level crosses said support columns (8), characterized in that said method includes: moving said object by or through an object-moving setup (18, 18', 18") at the same time that said object is guided by means of a guiding setup (22, 24, 40) included in said object-moving setup (18, 18', 18"), said object-moving setup (18, 18', 18") is at least partially located between said deck structure (2) and said raft (5), said object-moving setup (18, 18', 18") is fixed connected in at least one lateral direction to at least one of said support columns (8) and/or to said raft (6). 22. The method according to claim 21 further comprises: connecting said control set-up (22, 24, 40) to said object during movement. 23. The method according to claim 22 further comprises: releasing said object from said guide set-up (22, 24, 40) when a lower end of said object-moving set-up (18, 18', 18") is reached.