Abstract:
The invention concerns an assembly for transferring fluid ( 13 ) between a first site and a second site, comprising: a winch ( 40 ) for the first site ( 10 ) whereon is wound a suspension cable ( 17 ) designed to be stretched between the two sites ( 10, 11 ) and which is adapted to subject the cable to constant tension; a support ( 14 ) for the first site and for storing in suspension rigid pipe sections ( 15 ) mutually articulated via articulating sections ( 16 ) with rotary bends and joints, so as to shift from a storage position wherein the pipe sections ( 15 ) are suspended accordion-like to the support ( 14 ) to a stretched position between the two sites ( 10, 11 ) by being suspended to the cable; and means for coupling ( 22 ) some of the articulating sections ( 16 ) to the support ( 14 ) or to cable ( 17 ) depending on the length of the cable stretched between the two sites ( 10, 11 ).

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates, in a general manner, to systems for loading and/or unloading of fluids, especially from vessels for transporting the said fluids. A preferred field of application is the transfer of liquefied natural gas between a floating production storage and offloading (FPSO) platform and an oil tanker moored near this platform. 
     Among the methods of exploitation of offshore oil fields, the use of these independent floating production platforms is expanding rapidly. The installations are moved successively onto the separate offshore deposits, which become economically viable once their exploitation no longer requires the installation of a permanently fixed infrastructure. 
     One of the key points in the chain of exploitation is the transfer of the products obtained from the FPSO to the vessel that is to transport them. This operation is carried out on the open sea and therefore is strongly dependent on the sea conditions. 
     For this purpose, there is already a proposal to provide the FPSO with loading arms similar to those used on wharfs, an example of which is described in document GB-2 042 466. To carry out the loading/unloading operation, the vessel and the FPSO must be moored side by side, in the same way as in a port with a jetty. However, this mooring side-by-side is only possible in a very calm sea. 
     The use of loading and/or unloading systems like those described in documents FR-2 469 367 and EP-0 020 267 has also been proposed. These systems include a device for transferring fluid between a loading jib mounted on the FPSO and a coupling means provided on the vessel. The transfer device comprises a system of multiple articulated segments for fluid pipe of concertina or deformable diamond-shape(s) type and actutated by cable, the ends of the network being connected, by means of bends and rotary joints, respectively to pipe sections fixed to the jib and pipe sections that are to be connected to the coupling means. 
     Such a system permits loading or unloading in tandem in rough seas. However, it takes up a lot of space on the FPSO. 
     Other systems propose the use of floating or suspended hoses between the FPSO and the vessel, which are moored side-by-side or in tandem. 
     Although these systems make it possible to effect loading in very rough seas, the loading rate is limited by the flow rate in the hoses. Furthermore, these hoses offer limited resistance to pressure surges and the large radius of curvature of the hoses means that a large storage volume is required (large-diameter drum). This type of hose also has a limited service life and requires restricting periodical tests. Above all, however, the present state of hose technology does not permit cryogenic transfer. 
     In other embodiments, hoses joined by rotary joints form product lines that are supported by an articulated metal structure. 
     SUMMARY OF THE INVENTION 
     The present invention aims to improve the conditions of transfer of fluid between two locations, in particular between a first location on a floating production storage and offloading platform and a second location on a vessel that is to transport the fluid. 
     For this purpose, it proposes an arrangement for transferring fluid between a first location and a second location, comprising: 
     a control winch under constant tension that is to be installed at the first location, on which a suspension cable is wound which is to be stretched between the two locations and which is able to subject the suspension cable to a constant tension; 
     a storage stand that is to be installed at the first location for storing suspended rigid pipe elements that are articulated together by means of articulation sections provided with bends and rotary joints, in a manner that makes it possible to pass from a storage position in which the pipe sections are suspended in concertina fashion on the storage stand to a position spread out between the two locations by suspension from the cable for carrying out the transfer of fluid; and 
     means for coupling certain predetermined articulation sections to the storage stand or to the suspension cable depending on the length of suspension cable stretched between the two locations. 
     Such an arrangement with rigid pipework, with the individual elements connected together with rotary joints, permits a high fluid velocity and hence a high transfer rate. It also gives the pipework good resistance to pressure surges. 
     In addition, it makes it possible to transfer liquefied natural gas using existing cryogenic rotary joints, such as Chicksan® rotary joints. 
     Furthermore, as the suspension cable is subjected to a constant tension, it is wound onto its winch or unwound from the latter as a function of the movement of mutual separation or approach of the two structures. The number of predetermined articulation sections hung on this suspension cable therefore depends on the length of the latter stretched between the two structures. 
     Preferably, the coupling means comprise a plurality number of struts for suspending the predetermined articulation sections, to each of which a collet is fixed transversely for holding the suspension cable from above, to fix the suspension strut to the suspension cable, and the arrangement includes in addition a connecting winch that is to be installed at the second location, on which a connecting cable is wound, and this is to be connected to the suspension cable for taking it, prior to transfer of fluid, to the second location and securing it there or for bringing it back, after transfer of fluid, to the first location, all the while subjecting it to a constant tension by means of the constant-tension control winch. 
     On account of these arrangements, the connecting winch extracts the suspension cable and the articulated pipe sections from the storage stand, whereas the constant tension of the constant-tension control winch resists the exit of this cable and limits the deflection or sag of the suspended assembly. 
     For taking the connecting cable to the first location and connecting it to the suspension cable, the arrangement includes, advantageously, a winch that is to be installed at the first location, and on which a rope is wound, which is to be joined to the connecting cable for taking it to the first location in order to connect it to the suspension cable. 
     For fixing the connecting cable to the suspension cable, a mechanism with clamps, capable of firmly joining one end of the connecting cable to the suspension cable, is preferably fixed to one end of the latter. 
     Again preferably, the arrangement includes a device forming a mechanical stop, which is to be installed at the second location and has the purpose of locking the clamping mechanism, once the suspension cable is stretched between the two locations. 
     For reasons of convenience, the arrangement includes a means of fluid connection on an end pipe section and it is intended to be connected to a complementary means of fluid connection that is to be installed at the second location for executing the transfer of fluid. 
     According to characteristics that are preferred from the standpoint of the possibilities of movement offered by the latter: 
     at least some of the articulation sections that are to be hung from the suspension cable have a combination of a rotary joint with approximately vertical axis and of at least one rotary joint with approximately horizontal axis, with the pipe sections in the spread-out position; and/or 
     the coupling means have a plurality of suspension struts, each of which has a collet for holding the suspension cable from above, fixed transversely to one of its ends, and is joined to an articulation section by means of a pivot whose axis is roughly parallel to the direction of extension of the channel for receiving the suspension cable defined by the collet; and/or 
     the coupling means have a plurality of suspension struts, each of which is joined to the articulation section by means of a rolling bearing. 
     According to a preferred embodiment, the storage stand is mounted freely pivoting in azimuth on a base that is to be fixed at the first location and the arrangement includes in addition at least two sets of pulleys for lateral guidance of the suspension cable, fixed to the storage stand in different locations and capable of moving away from the suspension cable alternately on passage of a coupling means. 
     Due to these arrangements, the storage stand is aligned automatically on the suspension cable, while offering lateral flexibility of the product line formed by the pipe sections. 
     According to one embodiment variant, the storage stand is mounted pivoting in azimuth on a base that is to be fixed at the first location and the arrangement includes in addition a detector of the angular position of the suspension cable and a device for rotational control of the storage stand about the base, which is sensitive to filtered output signals of the detector for aligning the storage stand in the principal direction of the suspension cable. 
     According to another variant, the storage stand is connected rigidly to a base that is to be fixed to the first location, each articulation section that is to be hung on the suspension cable has a combination of a rotary joint with approximately vertical axis and of at least one rotary joint with approximately horizontal axis, with the pipe sections in the spread-out position; and the assembly has at least two sets of pulleys for lateral guidance of the suspension cable, fixed to the storage stand in two different locations and capable of moving away from the suspension cable alternately on passage of a coupling means. 
     According to preferred characteristics for their convenience of implementation, the coupling means have a plurality of suspension struts, to each of which a collet is fixed transversely for clamping the suspension cable from above, each of the collets having two articulated arms, which are moved towards a clamping position of the collet by the action of a spring, and each one provided with a roller, and the stand having two rails, each defining a rolling track for one of the rollers of the collet, the spacing of the rails being such that in the position of storage of the pipe sections, the collet is maintained in an open position against the force of the spring, permitting engagement of the latter on the suspension cable during passage of the pipe sections to the spread-out position. 
     For supporting the suspension cable as it leaves the storage stand, the arrangement includes, advantageously, suspension cable supporting pulleys, downstream from the rails of the storage stand. 
     The present invention also proposes the use of the arrangement described above for the transfer of liquefied natural gas between a floating production storage and offloading platform representing the first location and a vessel representing the second location, the pipe sections being connected by articulations to other pipe sections to form two pipelines for transfer of fluid which can be deployed simultaneously and parallel between the two locations, one of these pipelines serving for transfer of liquefied natural gas to the vessel and the other serving for return, of the vapour to the platform. 
    
    
     The present invention will be better understood on reading the description that follows, referring to the appended drawings which show, as examples, non-limiting embodiments of the present invention. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view according to a preferred embodiment of the invention; 
     FIG. 2 is a side view of the same arrangement; 
     FIG. 3 is a side view of a suspension strut of an articulation section of the arrangement in FIGS. 1 and 2; 
     FIG. 4 is a front view, with partial sectioning, of the same suspension strut in the storage position; 
     FIG. 5 is a view in longitudinal section of a clamping mechanism of the arrangement in FIGS. 1 and 2; 
     FIG. 6 is a sectional view along line VI—VI in FIG. 5, with partial sectioning; 
     FIG. 7 is a schematic illustration of the positioning of the means for lateral guidance of the suspension cable of the arrangement in FIGS. 1 and 2, on passage of the suspension strut shown in FIGS. 3 and 4; 
     FIG. 8 shows the same guidance means, in position for guiding the suspension cable; 
     FIG. 9 is a plan view of a system of suspension cable supporting pulleys; 
     FIG. 10 is a side view of the system in FIG. 9; 
     FIG. 11 is a plan view of one variant of implementation of the arrangement for transfer of fluid; 
     FIG. 12 is a side view of the arrangement in FIG. 11; 
     FIG. 13 is a front view of a device for detecting the angular position of the suspension cable of the arrangement in FIGS. 11 and 12; 
     FIG. 14 is a plan view of the device in FIG. 13; 
     FIG. 15 is a plan view of another variant of implementation of the arrangement for transfer of fluid; 
     FIG. 16 is a side view of the arrangement in FIG. 15; 
     FIG. 17 is a plan view of a variant of implementation of the arrangement for transfer of fluid for the transfer of liquefied natural gas; 
     FIG. 18 is an enlarged view of a first type of articulation section employed in the arrangements in FIGS. 1,  2 ,  11 ,  12 ,  15  and  16 ; 
     FIG. 19 is an enlarged view of a second type of articulation section employed in the arrangements in FIGS. 1,  2 ,  11 ,  12 ,  15  and  16 ; 
     FIG. 20 is an enlarged view of a first type of articulation section employed in the arrangement in FIG. 17; and 
     FIG. 21 is an enlarged view of a second type of articulation section employed in the arrangement in FIG.  17 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In FIG. 1, a part of an independent production platform is shown at  10 . A tanker  11  is moored by means of a hawser  12  to platform  10 . An arrangement for transfer of fluid  13  according to a preferred embodiment of the invention makes it possible to transfer, in this case, crude oil extracted on platform  10  to the tanker  11 . 
     For this purpose, arrangement  13  includes a stand  14  installed on platform  10  for storing, suspended, a number of rigid pipe sections  15  for transfer of fluid, crude oil in this instance, articulated together by means of articulation sections  16 ,  16 ′ provided with 90° bends and rotary joints, in such a way that they are able to pass from a storage position in which the pipe sections  15  are suspended in concertina fashion on stand  14  to a spread-out position between platform  10  and tanker  11  by suspension from a suspension cable or carrying cable  17  for executing the transfer of fluid (see FIG. 2, where the two positions are illustrated). 
     As can be seen more clearly in FIG. 18, the articulation sections  16  each have two 90° bends  18  connected at one end to an end of a rigid pipe section  15  and at their other end to the next 90° bend  18 , by means of a rotary joint  19 . The axis of this rotary joint  19  is approximately horizontal and perpendicular to the suspension cable  17 , when the articulation section  16  is suspended from it (see FIG.  1 ). This type of rotary joint  19  allows the pipe sections  15  to follow the curve of suspension cable  17  in the vertical plane, in the spread-out position of these pipe sections  15 , but also allows these pipe sections  15  to be folded for storage in concertina fashion on the storage stand or station  14 . 
     For identical reasons, the articulation sections  16 ′ are also each provided with a rotary joint  19 ′ with horizontal axis between two 90° bends  18 ′. However, a third 90° bend  18 ″ is provided between one of these 90° bends  18 ′ and the end of a rigid pipe section  15 . This third 90° bend  18 ″ is connected to the next 90° bend by a rotary joint  20  with approximately vertical axis in the spread-out position, permitting sideways movements of pipe sections  15 . These sideways movements enable the assembly to respond to the oscillating movements of tanker  11  and platform  10  during transfer. Furthermore, the twisting of this line is absorbed by an additional rotary joint  21  connecting the third 90° bend  18 ″ of articulation section  16 ′ to one end of pipe section  15  with which rotary joint  21  is aligned. 
     As can be seen in FIG. 1, because of these articulation sections  16 ,  16 ′, the pipe sections  15  are thus positioned alternately on either side of suspension cable  17  in the spread-out position. 
     It will also be noted that in the present preferred embodiment, every fourth articulation section is of the type with a vertical-axis rotary joint. 
     Coupling means are also provided for suspending these pipe sections  15  on storage stand  14  and on suspension cable  17  as a function of the length of the suspension cable  17  stretched between platform  10  and tanker  11 . 
     As can be seen in FIG. 2, the latter have suspension struts  22  that are connected, every other pipe section  15 , to an articulation section  16  or  16 ′ at the horizontal-axis rotary joint  19  or  19 ′, respectively. 
     The said suspension struts  22  are shown in more detail in FIGS. 3 and 4. 
     As can be seen in these diagrams, each suspension strut  22  is connected to an articulation section  16  by means of a rolling bearing  23  that has an inner ring  24  and an outer ring  25 , with balls  26  inserted between them. The inner ring  24  is fixed to the outside of the next rotary joint  19 , whereas the outer ring  25  is connected to the end of a vertical arm  27  of suspension strut  22  via a pivot joint  28 . 
     The axis of this pivot joint  28  is roughly parallel to the direction of extension of a receiving channel  29  defined by a collet  30  and intended to receive suspension cable  17 . 
     This collet  30  is integral with arm  27 , at its end opposite to that connected to ring  25 . It has two hinged arms  31 ,  32  stressed towards a clamping position of collet  30  by a spring  33  that is retained between arms  31  and  32  by a rod  34  mounted pivoting on arm  31  and engaging in a hole  35  in arm  32 . 
     It will also be noted that collet  30  is, in this case, fixed to arm  27 , transversely to the latter and permits clamping of suspension cable  17  from above. 
     It will be appreciated that pivot joint  28  allows misalignment between suspension cable  17  and the axis of the pipe formed by pipe sections  15  in the spread-out position. 
     As can also be seen in FIG. 4, each of the arms  31  and  32  is also provided with a roller  37   a ,  37   b  at its end opposite to that of clamping of suspension cable  17 . Each of these rollers  37   a ,  37   b  is in rolling engagement on a rail  38   a ,  38   b  of storage stand  14 . 
     In the storage position, the spacing of rails  38   a ,  38   b  is such that collet  30  is held in an open position, against the force of spring  33 , making it possible for the latter to engage on suspension cable  17  during passage of pipe sections  15  to the spread-out position. 
     A control system  39  (see FIGS. 1 and 2) is mounted on storage stand  14  and is equipped with a hydraulic actuator that is able to engage a collet  30  between rails  38   a ,  38   b  or to release the said collet  30  to enable it to be coupled to suspension cable  17 . 
     So that suspension struts  22  are hung on suspension cable  17  with a regular spacing, the control system is connected to an angular position sensor of a constant-tension control winch  40  installed on platform  10 , suspension cable  17  being wound on the said winch. 
     The unwound length of suspension cable  17  is measured by the angular position sensor and the corresponding information is transmitted to control system  39  which responds in the following way: 
     if cable  17  is in the course of being unwound and if a predetermined spacing is reached, a collet  30  is released to enable it to grip the suspension cable  17  and therefore make an articulation section  16  or  16 ′ integral with this cable  17 ; 
     if the cable is in the course of being wound onto winch  40  and if there is a collet  30  in front of the control system  39 , the hydraulic actuator of the latter will engage collet  30  between rails  38   a  and  38   b  and hold it in the storage position between these rails  38   a ,  38   b.    
     This operating logic is applied throughout the stage of transfer of fluid between platform  10  and tanker  11 , during which the separation between the latter can increase or decrease. 
     The constant-tension control winch  40  makes it possible to apply a constant tension to suspension cable  17  so as to maintain a roughly constant deflection at the mid-point of this cable  17 . For this purpose, winch  40  is operated by a hydraulic motor that is permanently submitted to a constant pressure. If tanker  11  moves away or comes closer, suspension cable  17  is wound onto winch  40  or is unwound from it; the (slight) variation in deflection is only due to variation of the range (the distance separating platform  10  and tanker  11 ). 
     The suspension cable wound on the said winch  40  is led to storage stand  14  by a 90° return pulley  41  mounted on a base  42  fixed to platform  10 . 
     Storage stand  14  is also mounted with azimuth pivoting on this base  42  by means of rolling bearings  43 . 
     Storage stand  14  is in addition connected to the deck of platform  10  by rollers  44  taking the weight of stand  14 . 
     A set  45  of other pipe sections articulated together by means of rotary joints and bends runs alongside base  42  to supply the pipeline formed by the sections  15  with crude oil, while being able to follow the pivoting of storage and  14  around base  42 . 
     The other end of this pipeline, positioned alongside tanker  11  in the spread-out position, is provided with a double-valve hydraulic coupling  46  that is to be connected to a manifold  47  located on tanker  11 . 
     To take suspension cable  17  and the pipe sections  15  that are fixed to it, from platform  10  to tanker  11 , a winch  48 , on which a connecting cable  49  is wound, is installed on the deck of tanker  11 . To take connecting cable  49  from the side of platform  10  so as to be able to fix it to suspension cable  17 , an ancillary winch  50  is provided on the deck of platform  10 , on which a rope  51  is wound. 
     As can be seen in FIG. 5, this rope  51  is provided, at one of its ends, with a loop  52  for coupling rope  51  to a socket  53  fixed on one end of connecting cable  49 . 
     To fix suspension cable  17  to connecting cable  49 , once the latter has been brought from the side of platform  10 , a clamping mechanism  54  is fixed to one end of suspension cable, 17 . Two return springs  55   a ,  55   b  hold socket  53  in place between jaws  56   a ,  56   b  when the cables are slackened. On the other hand, the tension of the cables tends to tighten jaws  56   a ,  56   b  on socket  53 , because the latter will, in the connected position, butt against a shoulder  57   a ,  57   b  of each of the jaws  56   a ,  56   b , which has the effect of causing the latter to pivot towards their holding position of socket  53 . 
     FIG. 5 also shows a part of a strut  58  with pivoting mounting on clamping mechanism  54 ; coupling  46  is fixed to this strut (see FIG.  2 ). 
     As can be seen in FIGS. 1 and 2, a first device forming a mechanical stop  59  is fixed to the storage stand  14  and a second device forming a mechanical stop  60  is installed on the deck of tanker  11 , close to manifold  47 . The first device forming stop  59  has the purpose of locking the clamping mechanism  54  as long as the procedure for deployment of suspension cable  17  and pipe sections  15  has not started, whereas the second device forming mechanical stop  60  serves the purpose of locking this same clamping mechanism  54 , once the suspension cable  17  is stretched between platform  10  and tanker  11 . 
     In the case of the present embodiment, the tensile force of suspension cable  17  is applied to base  42  via return pulley  41 . Storage stand  14  only bears the weight of pipe sections  15 . The said stand  14 , which can turn freely about base  42 , must therefore be aligned on suspension cable  17 . This alignment is obtained by means of lateral guidance pulleys, which can be seen in FIGS. 7 to  10 . 
     FIGS. 7 and 8 show a set of two pulleys  61  and  62  each mounted with pivoting on a supporting plate  63  by means of arms  64  and  65 , respectively. 
     These arms  64  and  65  are actuated so that they pivot about a common pivot  66  by means of two hydraulic jacks  67  and  68  each of which is fixed to the supporting plate  63 , on the one hand, and to one of the arms  64  and  65 , on the other hand. 
     Supporting plate  63  itself is fixed to storage stand  14 . 
     Thus, in a position shown in FIG. 8, where these pulleys  61  and  62  are in contact with the suspension cable  17 , on either side of the latter, any displacement of the said suspension cable  17  leads to a pivoting of storage stand  14  on base  42 , keeping storage stand  14  aligned with suspension cable  17  and, in consequence, also with the axis of the pipeline for transfer of fluid spread out between platform  10  and the tanker  11 . 
     As a result of this, the storage stand  14  is aligned automatically on suspension cable  17 . 
     On passage of a suspension strut  22  (see FIG.  7 ), the pulleys  61  and  62  are withdrawn from suspension cable  17  by operation of the hydraulic jacks  67  and  68 . The simplicity of such a system with two hydraulic jacks ensures good mechanical reliability. 
     However, for good lateral guidance to be maintained at all times, in fact two sets of pulleys are provided in different locations, and these move aside alternately during passage of a suspension strut  22 . 
     These two sets of pulleys are shown without their manoeuvring means in FIGS. 9 and 10. The first set of pulleys  61 ,  62 , which are also shown in FIGS. 7 and 8, can be seen, as well as the second set of pulleys  61 ′,  62 ′ positioned on either side of the suspension cable  17 , upstream of the first set of pulleys  61 ,  62 . 
     Owing to the alternating movements of tanker  11  during the loading phase of the latter, a suspension strut  22  can stop at any point of this pulley-based guidance system, and then start moving again in either direction, or may even oscillate about one position. 
     Accordingly, the control system  39  is connected to a position detector to allow it to change the order of the operations of withdrawal of the two sets of pulleys, depending on the detected position of a suspension strut  22 . 
     FIGS. 9 and 10 also show pulleys  69 - 72  for taking up the weight of the sections  15  on exit from storage stand  14 . 
     These pulleys  69 - 72  are connected, two by two, by connecting bars  73 - 76 , which in their turn pivot on intermediate bars  77  and  78  for suspending pulleys  69 - 72  on storage stand  14 . 
     The arrangement for transfer of fluid  13  operates in the following way: 
     Before the arrangement for transfer of fluid  13  is put in place, the pipe sections  15  are in the retracted position, i.e. they are suspended in concertina fashion on storage stand  14 . 
     For putting the arrangement for transfer of fluid  13  in place, first of all, rope  51  is taken from platform  10  to tanker  11 , for example passing it across at the same time as hawser  12 . An operative on tanker  11  then connects this rope to the end of connecting cable  49 , wound on its winch  48 . 
     Once connected, rope  51  is wound onto its winch  50 . It pulls on connecting cable  49 , which is unwound from its winch  48 . When the end of connecting cable  49  arrives at storage stand  14 , it is connected automatically to the end of suspension cable  17 . More precisely, socket  53  of connecting cable  49  separates the jaws  56   a ,  56   b  of clamping mechanism  54  and is held in position. Once connecting cable  49  is connected to suspension cable  17 , the connecting winch  48 , on tanker  11 , is started up, withdrawing from storage stand  14  the suspension cable  17  and the pipe sections  15  which are fixed to it progressively. The constant tension applied by winch  40  opposes exit of the suspension cable  17  and limits the deflection of the suspended arrangement for transfer of fluid  13 . As for the suspension struts  22 , they are fixed to this suspension cable  17  with regular spacing. 
     When the end of suspension cable  17  arrives at tanker  11 , the device for mechanical stop  60  locks the clamping mechanism  54 . The connecting winch  48  is then stopped and hydraulic coupling  46  is connected to a flange of manifold  47 . 
     The valves of coupling  46  are then opened and loading of tanker  11  can begin. 
     For the entire duration of the loading operation, the pipe sections  15  are retracted or come out of the storage stand, depending on the distance between platform  10  and tanker  11 . 
     For disconnection, the order of the operations is reversed and the movements are performed in the opposite direction. However, the principle of maintaining constant tension from platform  10  is preserved. 
     It will be appreciated that this arrangement for transfer of fluid  13  allows considerable relative movement in all directions. 
     In addition, it allows a high fluid velocity and in consequence a high transfer rate, while offering good resistance of the pipeline to pressure surges. 
     The variant of implementation shown in FIGS. 11 to  14  proposes a system for rotational control of the storage stand. 
     More precisely, the pulley system for lateral guidance of suspension cable  17  in FIGS. 1 to  10  is replaced with a system for rotational control of storage stand  14 , comprising an angular position detector  79  of suspension cable  17  (see FIGS. 13 and 14) and a device for rotational control  80  of storage stand  14  about base  42  (see FIG.  11 ). 
     The lateral direction of suspension cable  17  leaving storage stand  14  is measured by means of an idling roller  81  resting on the said cable  17 . This idling roller  81  is able to follow the sideways movements of cable  17  because it is mounted on a hinged support  82  mounted on a plate  83  fixed to storage stand  14  by means of two height-compensating hinges  84   a  and  84   b.    
     Hinged support  82  is also connected to a rotation encoder  85 . 
     The output signal from this encoder  85 , representing the angular position of suspension cable  17 , has been filtered so as to remove the intrinsic oscillations of the cable. This signal is transmitted to a hydraulic motor  86  of the device for rotational control  80  to align storage stand  14  with the principal direction of suspension cable  17  by means of a system of the rack and pinion type, in which the pinion is mounted on the output shaft of hydraulic motor  86  and the rack  87  is mounted on the deck of platform  10 , behind the rolling track  88  of rollers  44 . 
     Otherwise, the arrangement for transfer of fluid  13 ′ in FIGS. 11 to  14  is identical in all respects to the arrangement for transfer of fluid  13  in FIGS. 1 to  10 . 
     In the case of the variant of implementation in FIGS. 15 and 16, the storage stand  14 ′ of the arrangement for transfer of fluid  13 ″ is connected rigidly to platform  10 . 
     The sideways movements of tanker  11  relative to platform  10  are therefore completely absorbed at the outlet of storage stand  14 ′ by the suspension cable  17  and the pipeline for transfer of fluid formed by the pipe sections  15 . 
     Accordingly, the arrangement for transfer of fluid  13 ″ includes a system  89  for lateral guidance of suspension cable  17  as it leaves storage stand  14 ′, similar to that described with reference to FIGS. 7 to  10 . 
     In addition, articulation sections with a rotary joint with an approximately vertical axis, of the type of those shown in FIG. 19, are positioned on each suspension strut  22 . 
     Otherwise the operation of this arrangement for transfer of fluid  13 ″ is similar to that in FIGS. 1 to  10 . 
     It should be noted that the winch on which the rope is wound is not shown in FIGS. 15 and 16. This winch is identical to those shown in the other diagrams and can, for example, be located behind winch  50 . 
     Another embodiment of the arrangement for transfer of fluid is shown in FIG.  17 . 
     This arrangement for transfer of fluid  13 ′″ is intended for transfer of liquefied natural gas from platform  10  to tanker  11 . For this purpose it has a second network of pipe sections  15 ′ forming a pipeline for return of vapour from tanker  11  to platform  10 . 
     As can be seen in FIGS. 20 and 21, the pipe sections  15 ′ for vapour return are of smaller diameter than pipe sections  15  for transfer of liquefied natural gas. 
     Transfer of liquefied natural gas is carried out at a temperature of about −160° C., therefore all of the rotary joints used in this embodiment are cryogenic rotary joints of Chicksan® type joints. 
     Furthermore, so as to be able to deploy the two pipelines simultaneously and parallel between platform  10  and tanker  11 , the respective articulation sections  16 ,  16 ″ are joined together by means of transverse articulations  90 , as shown in FIGS. 20 and 21. 
     In this respect, it should be noted that the articulation sections  16 ″ in FIG. 21 each have just one rotary joint with approximately horizontal axis  91 ,  91 ′ associated with a joint with approximately vertical axis  92 ,  92 ′. 
     As for the articulation sections  16  in FIG. 20, they are identical to that shown in FIG.  18 . 
     Of course, the invention is in no way limited to the embodiments that have been described and illustrated, which have only been given as examples. 
     In particular, it comprises all means that constitute technical equivalents of the means described, as well as their combinations. 
     Furthermore, the arrangement for transfer of fluid according to the present invention can be used for transferring fluids other than crude oil and liquefied natural gas. Among these fluids, liquefied petroleum gas and condensates, can in particular be mentioned.