FIELD OF THE INVENTION

The present invention relates to an adjustable reel assembly for a spoolable product, an arrangement comprising an adjustable reel assembly and a spooled product, a vessel having an adjustable reel assembly for a spoolable product mounted thereto and a method of adjusting the capacity of a reel for a spoolable product. In particular, the present invention relates to an adjustable reel assembly for laying and retrieving flexible and semi-rigid product on the seabed, an arrangement comprising an adjustable reel assembly and a spooled flexible or semi-rigid product for laying or having retrieved from the seabed, a vessel including an adjustable reel assembly for laying and retrieving a flexible or semi- rigid product on the seabed and a method of adjusting the capacity of a reel for laying and retrieving a flexible or semi-rigid product on the seabed.

BACKGROUND TO THE INVENTION Various flexible and semi-rigid products are used within the oil and gas, telecommunications and energy industries. Such products include power and telecommunication cables, flexible flowlines, umbilicals, wire ropes, coiled tubing and other spoolable products. For the offshore industries, these spoolable products must be laid on and retrieved from the seabed.

In order to lay these spoolable products, the product is spooled onto a reel. The reel can be mounted to a vessel (for example a boat) which can then transport the reel to an offshore location. The reel comprises a powered reel such that the product can be unspooled from the reel and laid on the seabed. Alternatively, the product can be spooled onto the reel and retrieved from the seabed.

The reels are provided with releasable drive means to rotate the reel about a horizontal axis. The spoolable product thereby easily spools and unspools from the reel.

A vessel may be arranged to transport a number of reels and the drive unit may be mounted on tracks. During the laying of a product, once a first reel becomes empty, the drive unit can then be disconnected from the first reel. The drive unit can then be moved and then reconnected to a full second reel. Accordingly, the vessel can be used to lay (or retrieve) several reels consecutively. The reels are reusable and each reel can be used with different spoolable products. The diameters of such products may be different and, therefore, the capacity of the reels may vary depending upon the diameter of the spooled product. A number of reels may be required and the length of the product of each reel will vary depending upon the task.

In addition, spoolable products have a minimum bending radius below which the spoolable product should not be flexed or bent. This characteristic needs to be considered when a reel is selected. For example, a reel for a very flexible product may not be useable with a more semi-rigid product having a greater minimum bending radius. Such a reel for the semi-rigid product would need to have a greater spooling perimeter about the spooling hub.

The reels may be used globally and the reels may be transported in an empty state by sea using a suitable vessel relatively easily. However, such vessels may be a relatively expensive method of transporting the reels. Due to the size of the reels, it is difficult for the reels to be transported over land using either road or rail.

In some situations, only the partial capacity of a reel may be required. For example, the task may only require a relatively short length of a product. Alternatively, the task may require a number of full reels and only the partial capacity of a final reel. Accordingly, reels may be used whilst only holding a portion of its capacity. Since the reels are arranged horizontally, the product is easily retained around the hub and gravity does not cause the coils of the product to move along the hub or reel. However, in vertically arranged reels, there is a tendency for the coils of the product to move downwardly under gravity towards a lower flange of the reel. This may cause extra forces on the product as the product is unspooled. This can be especially problematic in products which have concentric layers (or sheaths/sleeves) since the layers may experience shear forces between the layers.

It is an aim of the present invention to overcome at least one problem associated with the prior art whether referred to herein or otherwise.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided a reel assembly for a spoolable product, the reel assembly comprising a reel and mounting means to mount the reel to a vessel, in which a spooling axis of the reel is arranged, in use, to be upstanding from the vessel, the reel comprising:

a spooling hub having a longitudinal length extending parallel to the spooling axis of the reel and a spooling perimeter around which the product can be wound;

a first retaining means; and

a second retaining means, wherein the first retaining means and the second retaining means are spaced apart along the longitudinal length of the spooling hub to define a spooling region around the spooling hub;

and wherein

the distance between the first retaining means and the second retaining means is adjustable; and

the spooling perimeter of the spooling hub decreases from the first retaining means towards the second retaining means. Preferably the spoolable product is a spoolable subsea product.

Preferably the spooling perimeter is adjustable in length. More preferably the length of the spooling perimeter is adjustable along the full length of the spooling hub in the spooling region.

Preferably the length of the spooling perimeter decreases from the first retaining means towards the second retaining means.

Preferably the length of the spooling perimeter decreases uniformly from the first retaining means towards the second retaining means.

Preferably the reel includes a support hub. Preferably the support hub is mounted about a (stub) axle and wherein the axle is preferably secured to or supported from the surface of the grillage (or vessel) at a single longitudinal end and preferably a second longitudinal end of the axle provides no support function.

Preferably the spooling axis is arranged to be upstanding from a surface of the vessel with the first retaining means being located towards the surface of the vessel and the second retaining means being located further away along the support hub (and/or the reel) relative to the surface of the vessel.

Preferably the first retaining means is arranged to locate on the spooling axis (and/or at/towards a (supporting) end of a support hub of the reel) proximal to the surface of the grillage (or vessel) and the second retaining means is arranged to locate on the spooling axis (and/or at/towards a (non supporting) end of a support hub of the reel) distal to the surface of the grillage (or vessel). Preferably the spooling axis of the spooling hub is arranged, in use, to be generally vertical and/or perpendicular relative to a support surface of a vessel. The support surface of a vessel may comprise a deck of a vessel. The vessel may comprise a boat, ship and/or barge.

The perimeter of the spooling hub may comprise a polygon and may comprise a regular polygon. The spooling perimeter of the spooling hub may be generally circular.

The spooling hub may comprise a plurality of hub elements. The hub elements may comprise longitudinal members. The plurality of hub elements may be arranged to provide a contiguous or an incomplete peripheral spooling surface.

The spooling hub may comprise a plurality of hub elements in which adjacent hub elements are spaced from each other to form longitudinal slots therebetween. Preferably the hub elements are moveable relative to the spooling axis. Preferably the hub elements are movable in a perpendicular direction relative to the spooling axis. Preferably the hub elements are radially moveable.

Preferably the hub elements are securable at different radial distances relative to the spooling axis and this may provide a spooling hub which has a spooling perimeter which is adjustable in length. The hub elements may be securable by a securement member. The securement member may be adjustable to secure the hub elements at different radial distances relative to the spooling axis.

The reel may comprise movement means to radially move the hub elements in order to adjust (increase or decrease) the (length of the) spooling perimeter of the spooling hub.

The hub elements may be angled to provide an angled spooling surface which extends inwardly towards the spooling axis from the first retaining means to the second retaining means.

The first retaining means may comprise a lower retaining means and the second retaining means may comprise an upper retaining means. The first retaining means may comprise a flange. Preferably the first retaining means comprises a generally annular flange. The second retaining means may comprise a series of retaining members. The retaining members may comprise radial retaining members. The retaining members may comprise spokes.

Preferably the series of retaining members effectively provides a retaining flange and more preferably generally provides an annular retaining flange.

The retaining members may extend from a central support hub.

The retaining members may be arranged to extend between longitudinal slots provided in the spooling hub.

The retaining members may be arranged to extend between longitudinal slots defined between adjacent hub elements forming the spooling hub. Preferably the retaining members are moveable along the spooling axis and, more preferably, the retaining members are simultaneously moveable along the spooling axis.

Preferably the retaining members provide a planar retaining barrier in a plane substantially perpendicular to the spooling axis.

Preferably the first retaining means is fixed (and immovable) relative to the spooling region. Preferably the second retaining means is moveable relative to the spooling hub. Preferably the second retaining means is moveable relative to the spooling hub along the spooling axis. Preferably the second retaining means is moveable relative to the spooling region.

Preferably the first retaining means and the second retaining means define annular boundaries on the spooling region (or on the spooling hub) along the spooling axis.

Preferably the first retaining means provides a planar retaining barrier in a plane substantially perpendicular to the spooling axis. The reel may be mounted to a mounting frame. The mounting frame may comprise a grillage.

The reel may be provided with drive means to rotate the reel about the spooling axis.

The drive means may be arranged to engage with the first retaining means in order to drive the reel.

The first retaining means may comprise a profile surface around a circular perimeter which is arranged to engage with one or more sprockets provided by the drive means.

The drive means may comprise a plurality of drive units (for example three drive units) located spaced apart around a perimeter of the first retaining means. Each drive unit may comprise two drive sprockets. The first retaining means may provide a sprocket for engagement with each drive means or drive unit. The drive may be transferred essentially using a rack and pinion arrangement.

The grillage may be arranged in use to be secured to a deck of a vessel.

Preferably the hub elements are radially moveable in a direction perpendicular to, and towards or away from, the spooling axis and the retaining members of the second retaining means are moveable in a direction parallel to the spooling axis and, therefore, the retaining members are moveable in a perpendicular direction relative to the hub elements. Preferably the hub elements are radially moveable in a first plane towards or away from the spooling axis and the retaining members of the second retaining means are moveable along the spooling axis and, therefore, the retaining members are moveable in a perpendicular direction relative to the hub elements. Preferably the movement of the hub elements towards the spooling axis increases the capacity of the reel for retaining a spoolable (subsea) product.

Preferably the movement of the hub elements away from the spooling axis enables the reel to accommodate a spoolable (subsea) product with a larger bending radius.

The hub elements may be secured by a securement member and preferably by an annular securement member. Preferably the securement member is arranged to space and retain the hub elements from a support hub and/or spooling axis by a predetermined distance. Preferably the securement member secures all of the hub elements equally around the spooling axis. The securement member may locate at a mid position along the spooling axis and the securement member may engage with central location of the hub elements. The securement member may comprise an expansion element.

Preferably the movement of the second retaining means towards the first retaining means decreases the capacity for the reel to retain a spoolable (subsea) product. Preferably the movement of the second retaining means away from the first retaining means increases the capacity of the reel to retain a spoolable (subsea) product.

Preferably the spooling axis is arranged to extend perpendicularly from a support surface such that the reel rotates in a plane parallel with the support surface. The spooling axis is arranged to be generally vertical such that the reel rotates in a generally horizontal plane. Preferably the reel comprises a modular reel. The modular reel may be constructed by releasably securing a number of individual components together.

According to a second aspect of the present invention there is provided an arrangement comprising an adjustable reel assembly and a spoolable product, the reel assembly comprising a reel and mounting means to mount the reel to a vessel, in which a spooling axis of the reel is arranged, in use, to be upstanding from the vessel, the reel comprising:

a spooling hub having a longitudinal length extending parallel to the spooling axis of the reel and a spooling perimeter around which the product can be wound;

a first retaining means; and

a second retaining means, wherein the first retaining means and the second retaining means are spaced apart along the longitudinal length of the spooling hub to define a spooling region around the spooling hub;

and wherein

the distance between the first retaining means and the second retaining means is adjustable; and

the spooling perimeter of the spooling hub decreases from the first retaining means towards the second retaining means.

According to a third aspect of the present invention there is provided a vessel having an arrangement comprising an adjustable reel assembly and a spoolable product, the reel assembly comprising a reel and mounting means to mount the reel to a vessel, in which a spooling axis of the reel is arranged, in use, to be upstanding from the vessel, the reel comprising:

a spooling hub having a longitudinal length extending parallel to the spooling axis of the reel and a spooling perimeter around which the product can be wound;

a first retaining means; and

a second retaining means, wherein the first retaining means and the second retaining means are spaced apart along the longitudinal length of the spooling hub to define a spooling region around the spooling hub;

and wherein

the distance between the first retaining means and the second retaining means is adjustable; and

the spooling perimeter of the spooling hub decreases from the first retaining means towards the second retaining means.

According to a fourth aspect of the present invention there is provided a method of adjusting the capacity of a reel for a spoolable product, the reel comprising:

a spooling hub having a longitudinal length extending parallel to the spooling axis of the reel and a spooling perimeter around which the product can be wound;

a first retaining means;

a second retaining means, wherein the first retaining means and the second retaining means are spaced apart along the longitudinal length of the spooling hub to define a spooling region around the spooling hub; and in which

the spooling perimeter of the spooling hub decreases from the first retaining means towards the second retaining means;

and wherein the method comprises:

providing the reel on mounting means mounted to a vessel such that a spooling axis of the reel is arranged, in use, to be upstanding from the vessel; and adjusting the distance between the first retaining means and the second retaining means.

According to a further aspect of the present invention there is provided a tensioner assembly for a reel for a spoolable product, the tensioner assembly comprising a tensioner and mounting means to mount the tensioner to a vessel and adjacent to the reel for a spoolable product wherein the reel is mounted to rotate about a spooling axis, the tensioner comprising:

engagement means for engaging the spoolable product as the spoolable product moves through the tensioner, and

wherein the tensioner is movable relative to the reel in order to adjust the distance between the tensioner and the spooling axis of the reel.

Preferably the tensioner is moveable relative to the reel in order to adjust the distance between the tensioner and the spooling axis of the reel to maintain a constant tension in the spoolable (subsea) product.

Preferably the tensioner is movable relative to the reel in order to adjust the length of a path for the spoolable (subsea) product extending between the reel and the tensioner to maintain a constant tension in the spoolable (subsea) product. Preferably the reel is arranged to rotate about a spooling axis and the tensioner is linearly movable on a platform relative to the reel in order to adjust the distance between the tensioner and the spooling axis to maintain a constant tension in the spoolable (subsea) product. Preferably the tensioner is moveable in a generally tangential direction relative to the reel. Preferably the tensioner is moveable in a direction generally parallel to a (substantially) tangent of the reel.

Preferably the tensioner is moveable in a plane parallel to a tangential plane of the reel.

Preferably the tensioner is moveable in a plane perpendicular to a spooling axis of the reel. Preferably a spooling axis of the reel locates within a spooling plane and the tensioner is moveable in a movement plane and wherein the movement plane is perpendicular to the spooling plane. The tensioner may be moveable along a movement axis which is perpendicular to a spooling plane and wherein the spooling plane bisects the reel into two generally hemi-cylindrical portions and the spooling axis lies in the spooling plane.

Preferably the tensioner is horizontally moveable. In addition, the tensioner may be vertically moveable.

Preferably the tensioner is moveable in a second direction.

Preferably the tensioner is secured to a support surface.

Preferably the tensioner is moveable in a plane generally parallel to the support surface. In addition, the tensioner may be moveable in a plane generally perpendicular to the support surface.

Preferably the tensioner assembly is secured to a support surface of a vessel. The support surface of a vessel may comprise a deck of a vessel. The vessel may comprise a boat, ship and/or barge.

The tensioner assembly may comprise a support structure or support frame to support the tensioner from the surface of a vessel. The support structure may comprise a tower and may comprise a level wind tower. Preferably the support structure is fixed to a surface of the vessel and the support structure is immovable relative to the surface of the vessel.

The support structure may comprise a support frame for supporting the tensioner therefrom. The tensioner may comprise a platform which is moveably engaged with the support frame of the support structure.

The platform may comprise at least one rail and preferably comprises two rails which may engage with corresponding bearing means provided in the support frame of the support structure. Preferably the platform comprises two longitudinal rails which each engage between longitudinally spaced bearing assemblies. The longitudinal rails may be located on the lateral sides of the platform. Each bearing assembly may comprise a plurality of bearing units. Each bearing assembly may comprise three bearing units. Each rail may be engaged between two bearing assemblies each comprising three bearing units such that each rail may be engaged by six bearing units. The platform may comprise two rails which are engaged between twelve bearing units. Preferably the assembly comprises movement means in order to enable the tensioner to move within the tensioner assembly.

Preferably the movement means comprises a positioning cylinder and a piston where the piston is extendable from the positioning cylinder and retractable into the positioning cylinder. One of the positioning cylinder and the piston may be mounted to the support frame and the other of the positioning cylinder and the piston may be secured to the platform of the tensioner.

Preferably the positioning cylinder comprises a passive cylinder and more preferably comprises a passive hydraulic cylinder.

Preferably the tensioner is moveable in a second direction.

Preferably the support frame is vertically moveable. The tensioner assembly may comprise movement means to vertically move the support frame (and tensioner) upwardly and downwardly in the support structure.

Preferably the support frame is vertically moveable in an upwards/downwards direction and the tensioner is moveable along an axis perpendicular to this movement.

Preferably the tensioner is moveable in a plane parallel to the support surface. For example, the tensioner assembly may be mounted on a generally horizontal support surface of a vessel and the tensioner may be arranged to move in a plane spaced from but parallel to the generally horizontal support surface. Preferably the tensioner is moveable relative to the reel in a single linear axis in order to adjust the length of a path for the spoolable (subsea) product extending between the reel and the tensioner to maintain a constant tension in the spoolable (subsea) product. Preferably the tensioner is arranged to move towards from the reel as the reel is decelerating.

Preferably the tensioner is arranged to move towards the reel as the operational speed (rotational speed or unspooling speed) of the reel is slower than the operational speed of the tensioner (or the speed of the tracks of the tensioner). Preferably this movement moves (and preferably extends) a piston against a constant force provided by the positioning cylinder.

Preferably the tensioner is arranged to move away from the reel as the reel is accelerating.

Preferably the tensioner is arranged to move away the reel as the operational speed (rotational speed or unspooling speed) of the reel is greater than the operational speed of the tensioner (or the speed of the tracks of the tensioner). Preferably this movement moves (and preferably retracts) a piston against a constant force provided by the positioning cylinder.

Preferably the tensioner assembly comprises control means in order to control the speed (and/or the position) of the tensioner within the tensioner assembly. Preferably the control means controls the speed (and/or the position) of the tensioner as the reel is accelerating and/or decelerating. Preferably the control means is arranged to control the relative speeds of the reel and the tensioner. More preferably the control means adjusts the speed of the tensioner to cause the tensioner to move away from or towards a null position.

Preferably the tensioner is arranged to move in order to compensate for the relatively slow accelerating/decelerating characteristics of the reel as compared to the tensioner to maintain a constant tension in the spoolable (subsea) product. Preferably the tensioner is arranged to move in order to compensate for unequal operating speeds of the reel relative to the tensioner. Preferably the operational speed of the tensioner is variable. The operational speed of the tensioner may be adjustable and this adjustment in speed may move the tensioner relative to within the assembly. Preferably the operational speed of the tensioner is adjusted relative to the operational speed of the spoolable product (and/or reel) in order to move the tensioner within the assembly.

According to another aspect of the present invention there is provided an arrangement comprising a tensioner assembly and a reel for a spoolable product, the tensioner assembly comprising a tensioner and mounting means to mount the tensioner to a vessel and adjacent to the reel for a spoolable product wherein the reel is mounted to rotate about a spooling axis, the tensioner comprising:

engagement means for engaging the spoolable product as the spoolable product moves through the tensioner, and

wherein the tensioner is movable relative to the reel in order to adjust the distance between the tensioner and the spooling axis of the reel.

Preferably the tensioner is moveable relative to the reel in order to adjust the distance between the tensioner and the spooling axis of the reel to maintain a constant tension in the spoolable (subsea) product. According to a yet further aspect of the present invention there is provided a vessel including a tensioner assembly and a reel for a spoolable product, the tensioner assembly comprising a tensioner and mounting means to mount the tensioner to the vessel and adjacent to the reel for a spoolable product wherein the reel is mounted to rotate about a spooling axis, the tensioner comprising:

engagement means for engaging the spoolable product as the spoolable product moves through the tensioner, and

wherein the tensioner is movable relative to the reel in order to adjust the distance between the tensioner and the spooling axis of the reel.

Preferably the tensioner is moveable relative to the reel in order to adjust the distance between the tensioner and the spooling axis of the reel to maintain a constant tension in the spoolable (subsea) product.

According to a yet another aspect of the present invention there is provided a method of tensioning a spoolable product of a reel, the method comprising providing a tensioner assembly for the reel for a spoolable product mounted to a vessel and providing the tensioner adjacent to the reel for a spoolable product wherein the reel is mounted to rotate about a spooling axis, the method comprising:

engaging the spoolable product with engagement mean as the spoolable product moves through the tensioner, and

moving the tensioner relative to the reel in order to adjust the distance between the tensioner and the spooling axis of the reel.

Preferably the tensioner is moveable relative to the reel in order to adjust the distance between the tensioner and the spooling axis of the reel to maintain a constant tension in the spoolable (subsea) product.

According to a final aspect of the present invention there is provided a carousel system comprising a reel assembly and a tensioner assembly and wherein the reel assembly is in accordance with the first aspect of the present invention and the tensioner assembly comprises a tensioner and mounting means to mount the tensioner to a vessel and adjacent to the reel assembly, the tensioner comprising: engagement means for engaging the spoolable product as the spoolable product moves through the tensioner,

wherein the tensioner is movable relative to the reel in order to adjust the distance between the tensioner and the spooling axis of the reel. Preferably the tensioner is moveable relative to the reel in order to adjust the distance between the tensioner and the spooling axis of the reel to maintain a constant tension in the spoolable (subsea) product.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of example only, with reference to the drawings that follow, in which: Figure 1 is a perspective view of a carousel system comprising a preferred embodiment of a reel for a spoolable subsea product and a preferred embodiment of a tensioner mounted on a level wind tower.

Figure 2 is a plan view of a carousel system comprising a preferred embodiment of a reel for a spoolable subsea product and a preferred embodiment of a tensioner mounted on a level wind tower.

Figure 3 is a side view of a carousel system comprising a preferred embodiment of a reel for a spoolable subsea product and a preferred embodiment of a tensioner mounted on a level wind tower.

Figure 4 is a front view of a tower of a carousel system including a preferred embodiment of a tensioner mounted on a level wind tower.

Figure 5 is a side view of a tower of a carousel system including a preferred embodiment of a tensioner mounted on a level wind tower. Figure 6 is a rear view of a tower of a carousel system including a preferred embodiment of a tensioner mounted on a level wind tower.

Figure 7 is a perspective view of a tower of a carousel system including a preferred embodiment of a tensioner.

Figure 8 is a top view of a tower of a carousel system including a preferred embodiment of a tensioner. Figure 9 is a bottom view of a tower of a carousel system including a preferred embodiment of a tensioner.

Figure 10 is a perspective view of a part of a tensioner mounted on a tower of a preferred embodiment of a carousel system.

Figure 1 1 is a perspective view of a tensioner mounted on a tower of a preferred embodiment of a carousel system.

Figure 12a and 12b are side views of a preferred embodiment of a reel with a second retaining means in an upper position without and with the hub elements respectively.

Figure 13a and 13b are side views of a preferred embodiment of a reel with a second retaining means in a mid position without and with the hub elements respectively.

Figure 14a and 14b are side views of a preferred embodiment of a reel with a second retaining means in a lower position without and with the hub elements respectively.

Figure 15a is a side view of a preferred embodiment of a reel with a single hub element in an inner position. Figure 15b is a view through A-A of Figure 15a.

Figure 16a is a side view of a preferred embodiment of a reel with a single hub element in a mid position.

Figure 16b is a view through A-A of Figure 16a.

Figure 17a is a side view of a preferred embodiment of a reel with a single hub element in an outer position.

Figure 17b is a view through A-A of Figure 17a.

Figure 18 is a side view of a preferred embodiment of a reel with all of the hub elements and in position.

Figure 19a and 19b are side and bottom views respectively of a preferred embodiment of a tensioner assembly with the tensioner platform located at a minimum distance.

Figure 20a and 20b are side and bottom views respectively of a preferred embodiment of a tensioner assembly with the tensioner platform located at a mid distance. Figure 21 a and 21 b are side and bottom views respectively of a preferred embodiment of a tensioner assembly with the tensioner platform located at a maximum distance.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described with particular reference to a spoolable subsea product although other similar spoolable products may be relevant. As shown in Figure 1 , Figure 2 and Figure 3, a typical arrangement for laying or retrieving a flexible or semi-rigid product from the seabed comprises a vessel, a reel, a powered reel drive, a tensioner and a level wind tower. It will be appreciated that this is only a basic, typical example, and the present invention is not limited to use with only this arrangement.

The flexible or semi-rigid spoolable subsea product may comprise a power or telecommunication cable, a flexible flowline, an umbilical, a wire rope, a coiled tubing or other spoolable product. The present invention will be described for use with a pipeline. The present invention is particularly suited for use in the oil and gas, telecommunications and energy industries although the present invention is not limited for use in only these industries. The basic operation of the arrangement of the carousel system on a vessel comprises the powered reel drive being operated wherein the pipeline will have earlier been loaded on to the reel and this loading ensures effective deployment of the pipeline. The pipeline passes through the tensioner and is guided into the sea by a chute. Depending upon the sea depth, weight and size of the pipeline etc, there will be a significant pull created as the pipeline is deployed. The tensioner helps to maintain a constant tension on the reel as the pipeline is laid and recovered. The present invention includes a tensioner assembly that primarily maintains the tension of the pipeline on the reel and a further tensioner(s) may also be used to maintain the tension of the product overboard.

The present invention will be described with reference to the laying of a pipeline rather than to the retrieval of a pipeline or to the spooling of the pipeline on to a reel. The reels are generally constructed from steel and have very large diameters, for example, up to 12 metres in diameter. Accordingly, such reels, especially when full or near to capacity with a spoolable product, requires significant rotational forces to rotate them. As it will be appreciated, such reels may require a period of time from initiation of the drive means in order for the reel to reach the required speed. Conversely, when stopping the reels, the reels will require a period of time to fully stop. During the acceleration phase, the tensioner is not operational and, therefore, but the reel will be deploying the pipeline and this could create undesirable forces in the pipeline. In this phase, the tensioner will move away from the reel to provide an extended path for the pipeline between the reel and the tensioner and the tensioner can then be started and the tensioner is a relatively quick accelerating device compared to the reel. The present invention provides a compensating means which enables the operation times (i.e. start up and switch off times of the tensioner and reel) to be off-set and in these phases the tensioner will move towards or away from the reel to compensate for the inequality in the operational speeds of the reel and tensioner and this maintains a constant tension in the spoolable subsea product.

In particular, during the start up phase, the reel is started before the tensioner and the tensioner is arranged to move away from the reel to maintain a constant tension in the spoolable product. Similarly, during the switch off phase the reel is powered off before the tensioner and the tensioner is arranged to move towards from the reel to maintain a constant tension in the spoolable product. The movement away from the reel compensates for the movement of the pipeline from the reel within a time frame between the reel starting to rotate and before the tensioner tracks are operating. Similarly, the movement towards the reel compensates for the lack of pipeline being unspooled from the reel after the reel has been stopped (or is slowing down) and the tensioner tracks are still operating. These movements keep the tension in the pipeline between the reel and the tensioner constant and this is achieved through the use of mounting the tensioner on a movable platform which moves relative to a static tower through the use of a passive cylinder. In particular, the moveable platform is moved against the pressure contained in the cylinder as a result of the build up in tension in the pipeline or the decrease in tension in the pipeline. The level wind tower 54 locates the control cabin 60 and supports the tensioner positioning system, both vertically and horizontally, and this is critical to the correct operation of the carousel system of the present invention. In particular, this function of the level wind tower 54 provides the carousel system with the function of the adjustable/compensated position of the tensioner 14 within the carousel system.

As shown in Figure 1 , Figure 2 and Figure 3, a preferred embodiment of a carousel system 10 comprises a reel 12 and a tensioner 14 for use with a pipeline (spoolable subsea product) in order to lay or retrieve the pipeline (spoolable subsea product) from an offshore location.

The reel 12 is a horizontally arranged reel 12 which is arranged to rotate about at vertical or upstanding spooling axis. In use, the reel 12 is mounted to a mounting frame comprising a grillage 30 which is secured on a deck of a vessel, in particular, on an exposed (rear) deck provided by a deck of a boat. The axis of rotation of the reel 12 extends perpendicularly from the deck. The reel assembly includes an axle which projects upwardly and a central support hub 25 of the reel 12 is arranged to rotate the reel 12 around this upwardly projecting axle.

The reel 12 is mounted to a mounting frame 30 which is fastened to the deck. The carousel system 10 includes drive means to rotate the reel 12 in order to spool or unspool the pipeline from the reel 12. In the preferred embodiment, the carousel system 10 includes six hydraulic motors 32 which are located spaced apart around the first retaining means comprising a lower flange 22 of the reel 12. The hydraulic motors 32 mesh with a corresponding engaging profiled surface 23 provided around the circumference of the lower flange 22. For example, the hydraulic motors 32 may each comprise a gear wheel which engages with the circumferentially toothed surface of the lower flange 22 such that the lower flange 22 effectively also forms a gear wheel.

The pipeline is arranged to extend from the reel 12 through the tensioner 14 and then the pipeline is guided over the edge of the vessel into the sea. In the retrieve configuration, the pipeline extends from the surface of the sea over the edge of the vessel and through the tensioner 14 and is then spooled onto the reel 12. Any suitable guide means may be used and such guides may be located between the tensioner 14 and the edge of the vessel.

As shown in Figure 4 to Figure 9, the tensioner is located on a tower 54, and specifically on a level wind tower. The tower 54 provides a support frame 51 for the tensioner 14 such that the tensioner 14 can be raised or lowered as the pipeline is spooled or unspooled from the reel 12. The frame 51 is moved vertically by an elevating cylinder 61 . This height adjustment mechanism ensures that the pipeline is spooled and unspooled from the reel 12 at an optimum angle as the amount of spoolable product on the reel 12 increases or decreases. The level wind tower 54 also includes a control cabin 60 and an access platform 62. This enables a user to sit within the control cabin 60 and control the operation of the carousel system 10. The tower 54 includes a grillage 55 and this provides securement means to enable the tower 54 to be secured to the deck of the vessel. The tensioner 14 comprises a known tensioner, for example, a tensioner provided by Aquatic Engineering and Construction Limited. In this example, a two track tensioner 14 is shown. This tensioner 14 includes two opposing tracks 50 which are urged towards each other to grip the outer surface of the pipeline. The tracks 50 grip the outer surface to enable the pipeline to be placed and maintained in tension. In particular, the tensioner 14 manages the tension of the pipeline on the reel. In other embodiments, a tensioner including a four tracked caterpillar track system could be used. Some systems may also include further tensioners to primarily control and manage the tension of the pipeline located overboard. The tensioner 14 is arranged to operate either in pay in, pay out, constant tension or render mode. The speed, tension and grip are displayed to the operator located in the control cabin 60. Overall, the above description generally describes a typical arrangement of a reel and tensioner system for laying and retrieving subsea cables. However, the present invention provides a carousel system including an adjustable reel assembly and a tensioner assembly providing a tension compensating system.

As shown in Figures 1 -3 and Figures 12-18, the reel 12 comprises an upper rim 19, a second retaining means comprising an upper flange 20 or flange members 21 , a first retaining means comprising a lower flange (or rim) 22, a (spooling) hub 24 and a supporting hub 25. The hub elements 26 are located in holes or apertures in the first locating surface and also in the top flange spokes. The hub elements 26 may locate in apertures in the first retaining means 22 and also in the upper rim 16 and/or the flange elements 21 . The pipeline or other spoolable product is arranged to be spooled around the spooling hub 24 between the flanges 20, 22. Since the present invention can be used with pipelines of different diameters and also with pipelines of different lengths, the full capacity of the reel 12 may not be required. The partial capacity of a reel may be used in such systems. However, in the present invention, the capacity of the horizontal reel 12 is adjusted to effectively provide a reel 12 having a different capacity.

The lower flange 22 and the upper flange 20 are both provided on the support hub 25 and are located at opposing positions relative to the spooling hub 24. The flanges 20, 22 define a spooling region on the spooling hub 24 around which the spoolable product can be stored and retained.

The distance between the upper flange 20 and the lower flange 22 is adjustable such that the longitudinal length (or axial length) of the spooling region of the spooling hub 24 is adjustable. This provides an adjustment system for adjusting the capacity of the reel 12. Figure 12a and Figure 12b show the upper flange 20 or false roof in an upper (top) position. Figure 13a and Figure 13b show the upper flange 20 or false roof in a mid position. Figure 14a and Figure 14b show the upper flange 20 or false roof in a lower (bottom) position. These Figures show the reel 12 without and with the individual hub elements 26 or radial posts in position.

In the preferred embodiment, the upper flange 20 is moveable downwardly whereas the lower flange 22 remains vertically fixed or static.

The upper flange 20 comprises a series of retaining or flange elements 21 or spokes which effectively provide the upper limit for the pipeline on the reel 12. These radial flange elements 21 can be moved downwardly relative to the spooling hub 24 and the lower flange 22 to decrease the longitudinal length of the spooling region.

As shown in Figure 1 and Figure 3, the hub 24 comprises a series of individual hub elements 26 or hub posts which are radially spaced apart and provide a series of longitudinal slots or axial slots between adjacent hub elements 26. The flange elements 21 are mounted and extend from a central support or the support hub 25 and the flange elements 21 are arranged to locate within these axial slots between adjacent hub elements 26. Accordingly, the upper flange 20 can be easily moved downwardly with respect to the spooling hub 24, as shown in Figure 3 and Figure 12b, Figure 13b and Figure 14b.

As mentioned above, the spooling hub 24 comprises a series or array of individual hub elements 26. These hub elements 26 are all moveable and are arranged to be simultaneously moved inwardly or outwardly in order to adjust the diameter of the hub 24. Again, this adjustment mechanism is used to adjust the capacity of the reel 12. The hub elements 26 are supported by a securement member 27 or spacing element. The securement member 27 (see Figures 15a, 16a and 17a) comprises an annular component that engages around the support hub 25. This securement member 27 locates mid-way along the longitudinal length of the support hub 25. The securement member 27 is configured or selected in order to space and retain the individual hub elements 26 at a predetermined radial distance from the support hub 25. This spacing thereby selects and determines the spooling hub diameter. Figure 15a and Figure 15b show a single hub element 26 being secured and retained by the securement member 27 at a minimum diameter for the spooling hub 24. Figure 16a and Figure 16b show a single hub element 26 being secured and retained by the securement member 27 at a mid diameter for the spooling hub 24. Finally, Figure 17a and Figure 17b show a single hub element 26 being secured and retained by the securement member 27 at a maximum diameter for the spooling hub 24. Figure 18 shows the complete hub with all of the individual hub elements being secured by the securement member 27 to form the spooling hub 24.

The outer surfaces of these hub elements 26 combine to provide a spooling perimeter about which the pipeline is wound. This spooling perimeter provides the spooling region. The spooling axis provides the central axis and the spooling perimeter lies in a plane perpendicular to this axis. The present invention enables the length of the spooling perimeter to be adjusted. In particular, the length of the spooling perimeter is simultaneously adjusted along the length of the spooling region along the spooling axis. An outer surface of the hub elements 26 is arranged to support the innermost windings of the spoolable product. The spooling region on the hub 24 may therefore comprise an incomplete (or non-continuous) surface. The spooling region may have a generally circular cross section with the hub elements 26 generally comprising elongate arcuate members.

The hub elements 26 are moveable relative to the rotational axis (or spooling axis) of the reel 12. As the hub elements 26 move away from the axis, the effective diameter (or the length of the spooling perimeter) of the hub 24 increases and this reduces the capacity of the reel 12. In addition, this increases the minimum bending radius. Conversely, as the hub elements 26 move towards the rotational axis of the reel 12, the capacity of the reel 12 increases since more windings can be retained in the spooling region. This will decrease the minimum bending radius. The longitudinal slots increase in width as the hub elements 26 move radially outwards and, similarly, the longitudinal slots decrease in width as the hub elements 26 move inwardly.

The adjustable diameter (or length of the perimeter) of the spooling hub 24 provides an expansion facility for the reel 12 and the spooling hub 24 does not actually structurally support the reel 12 since the reel is actually mounted to an axle by the support hub 25.

The hub 24 comprises a generally conical hub. The diameter (or spooling perimeter) of the hub 24 at the lower end located at or towards the lower flange 22 is greater than the diameter (or spooling perimeter) of the hub 24 at the upper end located at or towards the upper flange 20. The hub 24 thereby provides a generally frusto conical hub.

The generally conical hub is formed by the individual hub elements 26 being secured at an angle or, alternatively, with each hub element 26 having an angled outer hub surface vertical. From the lower end to the upper end, the hub elements 26 extend radially inwardly towards the rotational axis (or spooling axis) of the reel 12. This conical hub surface helps to retain the integrity of the spool and the windings of the spoolable product on the reel 12 as it is laid or retrieved. In particular, as the spoolable product is unspooled or spooled from a position spaced from the lower flange 22, there is a tendency for at least a part of the spoolable product to move downwardly under gravity since it is no longer supported from below. This unintentional unspooling may be more of a problem with some products than others and it may also vary depending upon the bending or flexing characteristics of the product. The present invention provides a carousel system tensioner compensation system (as explained herein) which addresses these and other potential problems.

The generally conical spooling hub 24 effectively creates a stack of adjacent windings to prevent or inhibit the unintentional unspooling. For example, a winding will be supported on a lower winding and there is a greater tendency for this with a conical hub. The upper winding would need to be moved radially further away from the rotational axis (or spooling axis) before it could be unspooled or unsupported when compared to a cylindrical spooling hub also since the cone is wider beneath the winding, it provides support above.

The carousel system including the tensioner assembly and the reel assembly is fully modular and can be containerised. All of the carousel system can be deconstructed and reconstructed from individual components. The tensioner assembly including the tensioner 14, the level wind tower 54 (including the control cabin 60 etc.) and all of the other components can be dismantled and packed for transport and/or storage. Similarly, the reel assembly including the reel 12, the grillage 30 etc. can be dismantled. The reel 12 comprises a modular reel in which the reel is constructed from a number of individual components which can be secured together to form the reel 12 and also separated such that the reel 12 can be easily transported within a container. This modular containerised reel 12 (or carousel system) enables the reel 12 (or carousel system) to be quickly and easily transported within a container by land or sea. The individual components will all fit within containers suitable for road transport. Accordingly, the reel 12 (or complete carousel system) of the present invention has the benefit and flexibility of being transported by road. The components are all secured together by releasable means such that the reel (or carousel system) is not deconstructed by cutting through the modular components and does not require welding to be reconstructed. All of these releasable securement means enable the reel 12 (or carousel system) to be constructed, deconstructed and reconstructed multiple times.

Accordingly, the present invention provides a carousel system in which the horizontal reel 12 has a generally conical spooling hub 24 and, in which, the capacity of the reel 12 can be adjusted either longitudinally by moving an upper flange 20 or radially by adjusting the diameter of the spooling hub 24. The adjustable feature for the perimeter of the spooling hub also enables the minimum bending characteristic of the reel to be controlled.

The carousel system 10 includes a tensioner 14 located downstream from the reel 12. The pipeline passes through the tensioner 14 and the tensioner 14 maintains tension in the pipeline and, in particular, manages the tension in the pipeline on the reel 12. The tensioner 14 comprises a known tensioner and, in this embodiment, the tensioner 14 comprises a two track tensioner 14. The tensioner assembly of the present invention is described with reference to its inclusion in a carousel system with the adjustable reel assembly. However, the tensioner assembly could be used in other carousel systems which may include vertical reels.

As shown in Figures 4-1 1 and Figures 19-21 , the tensioner 14 is mounted to the level wind tower 54 which is secured to the deck of the vessel. The level wind tower 54 is arranged to maintain the tensioner at the optimum position as the pipeline is spooled or unspooled form the reel 12. In particular, the level wind tower 54 maintains the tensioner 14 level, in respect of the vertical height, with the spooling or unspooling position of the pipeline on the reel 12. Accordingly, the level wind tower 54 provides a vertically moving support frame 51 which is maintained at the same height as the spooling/unspooling height of the pipeline on the reel 12.

The level wind tower 54 includes a grillage 55 which is secured to the deck of a vessel and, similarly, the reel 12 is also provided with a grillage 30 which is secured to the deck of the vessel. Accordingly, in the carousel system, the relative positions of the level wind tower 54 and the reel 12 are fixed. However, the present invention provides a tensioner 14 that is horizontally movable relative to the reel 12 in order to compensate for the effects of the inertia of the reel during acceleration and deceleration phases of the reel 12 or to compensate for unequal operating speeds of the reel 12 and the tensioner 14. The reel 12 is arranged to rotate at an operational speed such that the rate of pipeline being unspooled is controlled. Similarly, the tracks 50 of the tensioner are arranged to move at an operational speed such that a controlled amount of pipeline passes through the tensioner at the correct rate. It will be appreciated that these two amounts should be kept equal in that the unspooling speed (or rotational speed of the reel 12) should result in an amount of pipeline being unspooled which is the same as that which can be handled by tensioner 14. The tensioner operational speed is controlled by the speed of the tensioner tracks 50. If the operational speed of the reel is different from the operational speed of the tensioner then, previously, this would result in a build up in tension of the pipeline or in a decrease in the required tension in the pipeline. The present invention provides an automatic compensation system for these variations in tension caused by unequal operational speeds. During an acceleration phase of the reel 12 (or when the reel 12 is operating faster than the tensioner 14), the separation distance between the reel 12 and the tensioner 14 is arranged to increase. In this acceleration phase, the tensioner tracks may not be being driven or at least not driven at full speed. This allows for the effects of the inertia of the reel 12 which means that the reel 12 is relatively slow to accelerate compared to the tensioner 14. Conversely, during a deceleration phase of the reel 12 (or when the reel 12 is operating slower than the tensioner 14), the separation distance between the reel 12 and the tensioner 14 is arranged to decrease. In this phase, the tensioner tracks may still be being driven at full operational speed. During the initial acceleration phase, the tensioner 14 may not be operable and this enables the reel 12 to get up towards operating speed. Similarly, the compensation system allows for the inertia effect which results in the reel 12 being relatively slow to decelerate compared to the tensioner 14. During the final switch off phase, the tensioner 14 may still be operating at a normal operating speed whilst the reel 12 is gradually slowing down.

The tensioner operation is as follows. The tensioner 14 is mounted on a moveable platform 52 which is connected to the fixed support frame 51 by a passive hydraulic cylinder 56 which has the facility for a constant pressure supply to be connected to the annular side of the cylinder to maintain a constant force on the tensioner platform 52 when the hydraulic supply is present. With the platform 52 in its null position and no supply to the platform cylinder the tensioner 14 is engaged with the spoolable product to grip it with the required grip force. The constant pressure supply to the platform cylinder 56 is then turned on which provides the predetermined constant tension in the product.

Due to the high inertia of the reel 12 in relation to the tensioner 14, the tensioner 14 has the faster response time and thus the speed of the tensioner 14 is used as the controlling parameter for the system.

During start up the reel 12 will be started first, spooling out product and allowing the tensioner platform 52 to initially move away from the reel 12 under the influence of the constant force generated by the platform cylinder 56 which maintains a constant tension in the product. A feedback of the platform 52 position relative to its null position is provided to the operator who will start to synchronise the speed of the tensioner 14 with the reel 12 thereby allowing the tensioner platform 52 to move back towards to its null position whilst still maintaining constant tension in the product. Once the speed of the reel 12 and tensioner 14 are closely synchronised the tensioner platform 52 will be maintained at or close to its null position by minor adjustment of the speed parameters of the tensioner 14 with constant tension in the product being maintained at all times by the platform cylinder 56.

During shutdown, the speed of the reel 12 will be reduced first slowing the spooling out of the product and allowing the tensioner platform 52 to initially "climb" along the product towards the reel 12, constant tension in the product being maintained by the constant force generated by the platform cylinder 56. Again a feedback of the platform 52 position relative to its null position is provided to the operator who will closely synchronise the speed of the tensioner 14 with the reel 12 to allow the tensioner platform 52 to move back towards to its null position whilst still maintaining constant tension in the product. Both the reel 12 and tensioner 14 will be brought to a complete stop such that the tensioner platform 52 is at the null position with the constant tension maintained in the product. The tensioner 14 is mounted to a moveable platform 52 which is mounted on the support frame 51 and, in particular, the tensioner 14 is moveably mounted to the support frame 51 . The support frame 51 moves vertically on the tower 54. The support frame 51 is vertically moveable to maintain the tensioner 14 in alignment with the pipeline as the pipeline is spooled or unspooled from the reel 12. However, the tensioner 14 itself is moveable horizontally on the support frame 51 .

The tensioner 14 is mounted to a moveable platform 52 which is moveable relative to the support frame 51 . The platform 52 provides two elongate horizontal longitudinal rails 53 which are engaged with bearing assemblies 57 provided on the support frame 51 . In particular, each rail 53 is engaged within two bearing assemblies 57 which are positioned at each end of the support frame 51 and spaced apart along the length of the rail 53. Each bearing assembly includes three bearing mountings. Overall, the platform 52 is moveably supported within the four bearing assemblies 57 which comprise a total of twelve bearing mountings.

The lateral (horizontal) cylinder 56 and the vertical cylinder 61 act together to ensure the tensioner 14 is correctly positioned for the product and spooling. The support frame 51 also includes platform movement enabling means in the form of a platform positioning cylinder 56. The platform positioning cylinder 56 comprises a passive hydraulic cylinder. The platform positioning cylinder 56 acts as a constant tension spring. In the preferred embodiment, the platform positioning cylinder 56 is secured to the support frame 51 and a piston 59 provided within the cylinder 56 is arranged to retract into this cylinder 56 and extend therefrom. The distal end of the piston 59 is secured to the platform and may be secured to a lateral frame member of the platform 52. Accordingly, the platform positioning cylinder 56 enables the platform (and hence the tensioner 14) to move towards or away from the reel 12. This movement will either shorten or lengthen the amount of pipeline located between the tensioner 14 and the reel 12 especially during the start up phase or the shut down phase to compensate for the inertia of the reel 12 and/or for the inequalities in the speed of the reel 12 relative to the tensioner 14. The platform positioning cylinder 56 effectively keeps the pipeline at a constant tension whilst the reel 12 and the tensioner 14 are operating at different speeds. As mentioned above, the speed of the tensioner 14 can be varied to synchronise these speeds but in relatively short periods of time (for example during the initial start up/final shut down) the compensation system provided by the movable platform 52 and passive cylinder 56 are used to maintain constant tension in the pipeline.

Figure 10 and Figure 1 1 show more detailed views of the arrangement of the tensioner 14 being supported by the support frame 51 through the moveable platform 52.

The support frame 51 is maintained in a horizontal plane (or parallel plane) relative to the deck of the vessel.

The tensioner 14 is arranged to move in a substantially horizontal direction. It is appreciated that a theoretical horizontal direction is not practically relevant, in use, since the carousel system 10 may be mounted on the deck of a boat which may include heave (linear vertical up/down motion), sway (linear lateral side to side motion) and surge (linear longitudinal front/back motion). In addition, the boat may be pitching, rolling and/or yawing. The horizontal movement is made with reference to the reel 12, i.e. the movement increases or decreases the distance between the reel 12 and the tensioner 14. It is also realised that the theoretical length of the pipeline between a reel 12 and a tensioner 14 may vary as the pipeline spools or unspools. For example, due to the spooled configuration, the length of pipeline extending between a full reel and a tensioner will be less than the length of a pipeline extended between a near empty reel and a tensioner. However, in such systems, the tensioner does not move in a direction away or towards the reel. Such a tensioner may move upwardly and downwardly but the separation distance between the spooling axis of the reel and the tensioner remains constant. The aim of the present invention is to enable the separation distance to change to maintain constant tension in the spoolable subsea product to allow for unequal acceleration/deceleration characteristics of the reel 12 and the tensioner 14 and to allow for unequal operating speeds of the reel 12 and the tensioner 14 over relative short periods of time. The tensioner 14 and the platform 52 are arranged to move relative to the support frame 51 along a single linear axis. In particular, this movement axis is arranged perpendicular to the rotational (spooling) axis of the reel 12. As previously described, the rotational axis of the reel 12 is vertical (perpendicular) relative to the deck to the vessel and the movement axis of the tensioner 14 is horizontal relative to the deck of the vessel. The movement axis of the tensioner 14 is generally tangential relative to the spooling axis of the reel 12. The movement of the tensioner 14 is in the same direction as the direction of the spoolable product through the tensioner 14. Figure 19a and Figure 19b show the tensioner 14 and the moveable platform 52 being located at a minimum distance relative to the reel (not shown) with the support frame 51 of the level wind tower 54 being located at a lower position. Figure 20a and Figure 20b show the tensioner 14 and the moveable platform 52 being located at a mid distance relative to the reel (not shown) with the support frame 51 of the level wind tower 54 being located at a lower position. Figure 21 a and Figure 21 b show the tensioner 14 and the moveable platform 52 being located at a maximum distance relative to the reel (not shown) with the support frame 51 of the level wind tower 54 being located at a lower position. Overall, the carousel system 10 comprises a horizontal reel 12 with an adjustable capacity and with a conical spooling hub 24 to help support the windings on top lower windings and wherein the carousel system also includes a tensioner 14 which is moveable towards and/or away from the reel 12. In particular, the tensioner 14 is moveable in a linear tangential direction relative to the spooling axis of the reel 12.

The direction of movement of the tensioner 14 may be perpendicular to a central axial plane of the reel 12. The spooling hub 24 comprising the hub elements 26 may comprise a frusto pyramid with a regular polygonal base.