Device for laying an elongate element in a stretch of water, associated installation and associated method

This device comprises a drum (42) to be driven in rotation about a central axis (B-B′), wherein the drum (42) defines a circumferential casing (50) for winding the elongate element around the central axis (B-B′), wherein the elongate element is intended to form at least one turn around the central axis (B-B′) on the circumferential casing (50). It comprises a mechanism (44) for driving the turn(s) of the elongate element along the circumferential casing (50). The drive mechanism (44) comprises at least one assembly (80) following movement of the turn in a direction of movement (D) forming a non-zero angle with the local axis of the turn, taken at a contact region of the turn on the movement assembly (80).

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a 35 U.S.C. §§371 national phase conversion of PCT/EP2014/061619, filed Jun. 4, 2014, which claims priority of French Patent Application No. 13 55171, filed Jun. 5, 2013, the contents of which are incorporated by reference herein and French Patent Application No. 13 55771, filed Jun. 19, 2013, the contents of which are incorporated by reference herein. The PCT International Application was published in the French language.

The present invention relates to a device for laying an elongate organ in a stretch of water, comprising:a drum intended to be driven in rotation about a central axis, wherein the drum defines a circumferential casing for winding the elongate organ about the central axis, wherein the elongate organ is intended to form at least one turn about the central axis along the circumferential casing;a mechanism for driving the turn(s) of the elongate organ along the circumferential casing.

The elongate organ is, for example, a pipe. The pipe is especially designed to carry oil collected in the bottom of the stretch of water to the surface of the stretch of water.

The pipe is, in particular, a flexible pipe stored in a floating structure and unwound in the stretch of water through the laying device.

In all that follows, a flexible pipe is especially a pipe as described in normative documents published by the American Petroleum Institute (API) API 17J and API RP17B, which are well known to the person skilled in the art.

This definition equally encompasses flexible pipes of unbonded or bonded types.

More generally, and alternatively, the flexible pipe is a composite of the “bundle” type, comprising at least one fluid conveyance tube and a plurality of electrical or optical cables suitable for carrying electrical or hydraulic power or information between the bottom and the surface of the stretch of water.

In another variant, the pipe is an umbilical pipe as described in normative documents of the American Petroleum Institute (API) API17E.

More generally still, the elongate organ is a cable forming, for example, a line of descent of an object in the stretch of water. This cable is, for example, a metal cable or a cable made of synthetic fibres.

To deploy flexible conduits, it is known to unroll them from storage means present on the ship. The storage means are especially a basket or a rotating drum.

The conduit is unwound from a storage means, and is generally raised via a channel on a tower of the laying device.

Next, the conduit is part of sensing and movement assemblies including chain tensioning. Thus the conduit descends vertically or obliquely along the tower before submersing into the stretch of water.

The conduit is retained by the tensioning means which ensure its suspension in the stretch of water. In addition, the tensioning means support the mechanical tension resulting from the weight of the unwound pipe and avoid the storage means having to support this weight, while ensuring that the conduit is not subject to any bending that goes beyond its Minimal Bending Radius without causing damage (“MBR” or “Minimal Bending Radius” in English).

Another method of laying is the so-called “S-lay method”. The elongate organ stored in a basket is deployed in the stretch of water through the back of the laying structure while being guided by a guiding channel designed by the English term “stinger”.

Tensioning means positioned on the deck of the ship or on the stinger generally determine the speed of the unwinding of the conduit.

In another known laying device, the presence of tensioning means is not necessary. In this case, the elongate organ is wound around the drum of a winch between the storage means and the stretch of water. The elongate organ forms a plurality of turns wound around the drum axis to provide a retaining tension of the elongate organ section introduced into the stretch of water. This retention is based on the principle of the “capstan” effect.

To ensure the deployment of the elongate organ in the stretch of water, the drum is motorised and the elongate organ is gradually unwound in the stretch of water.

One such laying device is simple and compact. However, it is not completely satisfactory.

In order to ensure effective retention of the immersed section of the elongate organ, it is necessary to have a large number of turns around the drum to ensure sufficient friction between the turns of the elongate organ and the drum. However, this high friction constraint acts against the need to ensure sliding of the elongate organ between its point of entry on the drum and its point of exit from the drum, in order to slide laterally the other turns already introduced on the drum.

When the tension applied to the elongate organ is significant, it is difficult to implement a laying device using the capstan effect because the lateral forces required to push the turns are too great, and produce adverse effects on the elongate organ, such as crushing, rotation or twisting of the elongate organ.

To overcome this problem, WO 2012/044179 discloses a laying device of the above-mentioned type, wherein an endless chain is wound around the drum along a helical path which continuously follows the local axis of the turns of the elongate organ.

The chain is provided with pads which serve to guide and move the elongate organ progressively as it unwinds in the stretch of water, by driving the drum in rotation about its axis.

This solution improves the unwinding of the elongate organ. However, it requires a bulky laying device, while the management of the transmission of forces between the chain and the drum is not easy to implement.

The return section of the chain section between the exit from and the entrance to the drum added to the device size, makes the passage of the upper radially extending sections of the elongate organ, such as the end pieces, difficult.

Thus, an object of the invention is to design a device for laying an elongate organ in a stretch of water that is simple to implement, while providing compactness and maximum ease of use, particularly with an elongate organ having major radially extending sections.

To this end, the invention relates to a device of the above-mentioned type, characterised in that the drive mechanism comprises at least an assembly to move the turn in a direction of movement forming a non-zero angle with the local axis of the turn at a contact region of the turn on the movement assembly.

The device according to the invention may include one or more of the following features, in isolation or in any technically feasible combination:the direction of movement forms an angle of at least 10°, preferably at least 45° with the local axis of the turn measured at a contact region of the turn on the movement assembly;the direction of movement forms an angle of less than 80°, preferably less than 45° with an axis parallel to the central axis of the drum rotation, the movement direction preferably being parallel to the central axis of the drum rotation;the movement assembly extends angularly around the central axis over an angular extent less than 360°, in particular less than 45°;the drive mechanism comprises a plurality of movement assemblies of the or each turn in a direction of movement, wherein the direction of movement forms a non-zero angle with the local axis of the turn, taken at a contact region of the turn over the entire movement, wherein the movement assemblies are distributed angularly around the central axis;the movement assembly has an endless organ that is movable in the direction of movement, and an assembly to set in motion the endless organ, wherein the endless organ and the setting in motion assembly are carried by the drum to be moved jointly with the drum in rotation about the central axis;the endless organ comprises a chain and a plurality of pads mounted on the chain, wherein each pad defines a channel to receive a turn of the elongate organ;the setting in motion assembly is adapted to move the endless organ in the direction of movement by the effect of the driving in rotation of the drum about the central axis;the drum comprises two lateral flanges and a linkage assembly connecting the two side flanges, wherein the linkage assembly defines the circumferential casing, and wherein the linkage assembly delimits at least one outer channel for each movement assembly to receive the movement assembly opening radially away from the central axis;the linkage assembly comprises a plurality of axial beams connecting the flanges to one another, wherein the outer receiving channel is delimited by two adjacent axial beams;an outer section of the endless organ is received in the outer channel, wherein the linkage assembly delimits an inner channel to receive an inner section of the endless organ, and wherein the inner channel opens radially towards the central axis, opposite to the outer channel;it comprises a plurality of movement assemblies, wherein an outer section of the endless organ of each movement assembly is received in an outer channel, and an inner section of the endless organ of each movement assembly is received in an inner channel, wherein at least a first group of inner channels is offset radially away from the central axis with respect to a second group of inner channels;it comprises a radial displacement mechanism of a region of the movement assembly away from the central axis, or towards the central axis.

The invention also relates to an installation for laying of an elongate organ in a stretch of water, characterised in that it comprises:a surface assembly extending on the surface of the stretch of water;a device as described above, carried by the surface assembly, wherein the drum is rotatably mounted on the surface assembly around the central axis;an elongate organ having at least one turn wound around the drum, wherein a contact region of the turn is arranged on the movement assembly, and the direction of movement defined by the movement assembly forms a non-zero angle with the local axis of the turn measured at the contact region.

The invention also relates to a method of laying an elongate organ in a stretch of water, comprising the following steps:providing an installation as described above, wherein the elongate organ has at least one turn wound around the drum;rotating the drum about the central axis to lower or raise the elongate organ in the stretch of water;simultaneously, moving by the movement assembly of at least one turn of the elongate organ in a direction of movement forming a non-zero angle with the local axis of the turn at a contact region supporting the turn on the movement assembly.

A first laying installation10according to the invention is shown inFIGS. 1 to 5.

The installation10is intended for laying an elongate element12in a stretch of water14.

The stretch of water14is, for example, a sea, an ocean or a lake. The depth of the stretch of water14between the surface16and the bottom18in line with the installation10is greater than 10 meters and, in particular, between 100 meters and 4000 meters.

The elongate element12is, for example, a pipe. The pipe is especially designed to carry oil collected in the bottom of the stretch of water to the surface of the stretch of water.

In particular, the pipe is a flexible pipe unwound in the stretch of water14through the laying installation10.

In all that follows below, a flexible pipe is especially a pipe as described in normative documents published by the American Petroleum Institute (API) API 17J and API RP17B, which are well known to the person skilled in the art.

This definition equally encompasses flexible pipes of the type unbonded (“unbonded” in English or bonded type (“bonded” in English”).

More generally, and alternatively, the flexible pipe is a composite beam of the “bundle” type, comprising at least one fluid conveyance tube and a plurality of electrical or optical cables suitable for carrying electrical or hydraulic power or information between the bottom and the surface of the stretch of water.

In another variant, the pipe is an umbilical pipe as described in normative documents of the American Petroleum Institute (API) API17E.

More generally still, the elongate organ12is a cable forming, for example, a line of descent of an object in the stretch of water. This cable is, for example, a metal cable or a cable made of synthetic fibres. The elongate element12may carry equipment such as nozzles or equipment to be used on the bottom which locally have a greater average transversal extent than the transversal extent of the elongate element12.

Referring toFIG. 1, the laying installation10comprises a surface assembly20, a storage assembly22of the elongate element12carried by the surface assembly20, and a laying device24according to the invention, formed by a capstan winch.

The surface assembly20is partially immersed in the stretch of water14. Preferably, the surface assembly20floats on the surface16of the stretch of water14. It is, for example, formed by a laying ship, a platform or a barge.

In the example shown inFIG. 1, the surface assembly20has a hull26floating on the stretch of water14. The hull preferably delimits a wellbore28intended to receive the descent of the elongate element12in the stretch of water14.

The wellbore28passes through the hull26. It opens up on a deck30of the hull26. It opens downwards into the stretch of water24.

The storage assembly22is formed by a rotary organ32storing the elongate element12in a wound configuration. The rotary organ32is, for example, a drum or a basket.

The storage assembly22is arranged on the deck30or in the hull26.

The rotation of the storage organ32in a first direction about its axis A-A′ allows the unwinding of an increasing length of the elongate element12towards the laying device24, while rotation in a second direction opposite to the first direction allows the rewinding of an increasing length of the elongate element12on the storage organ32.

Referring toFIG. 1, the laying device10comprises a support40fixedly mounted on the surface assembly20, a drum42mounted to rotate about a central axis B-B′, and a drive unit43for driving the rotation of the drum42about the central axis B-B′.

As shown inFIGS. 2 to 5, the laying device10according to the invention further comprises a drive mechanism44for driving at least one turn of the elongate element12on the drum42as described in detail below.

In this example, the central axis B-B′ of rotation of the drum42is horizontal.

Referring toFIG. 3, the drum42comprises two lateral opposing flanges45,46and a linkage assembly48connecting the flanges45,46defining a circumferential casing50for winding the elongate element12about the central axis B-B′.

In this example, each flange45,46is formed by a disc-shaped organ extending transversely with respect to the axis B-B′.

The linkage assembly48forms a barrel of the drum42. It comprises here a plurality of axial beams52,54connecting the flanges45,46together, parallel to the axis B-B′.

As shown inFIG. 2, the linkage assembly48thus comprises a first group of axial outer beams52, distributed angularly about the axis B-B′ and a second group of axial inner beams54, arranged closer to the axis B-B′ than the axial outer beams52.

In this example, the outer beams52are arranged in pairs of parallel beams. The outer beams52of each pair are connected, two by two, by an outer bottom wall56.

Thus, the outer beams52define a plurality of outer channels58, closed towards the axis B-B′ by the bottom wall56and opening outwards away from the axis B-B′.

The outer channels58are angularly distributed about the axis B-B′. Each outer channel58extends here along a direction of movement D intended to form a non-zero angle with the local axis of each turn of the elongate element12wound around the drum42.

In this example, the direction of movement D is parallel to the axis B-B′.

Advantageously, each outer channel58extends continuously to the respective flanges45,46.

In addition, first sections of the outer pairs of beams52are connected in pairs by an inner bottom wall60. They therefore define a first group of inner channels62, closed away from the axis B-B′ by the inner bottom wall60and opening inwards towards the axis B-B′.

In this example, each inner beam54projects from the bottom wall60of one pair of outer beams52.

Each inner beam54carries an inner channel64of a second group of inner channels64.

Each inner channel64is closed away from the axis B-B′ and opens inwards towards the axis B-B′.

The inner channels64of the second group of inner channels64are located closer to the axis B-B′ than the inner channels62of the first group of inner channels62.

In a preferred embodiment, the inner channels62of the first group are staggered relative to the inner channels64of the second group.

More generally, each inner channel62,64extends opposite an outer channel58in a direction parallel to the direction of movement D.

Each inner channel62,64extends continuously between the flanges45,46.

The staggered arrangement of the inner channels62,64ensures maximum compactness of the drive mechanism44.

The drum42is adapted to be driven in rotation about the central axis B-B′ by the drive unit43to allow the unwinding of the elongate element12from the storage assembly22towards the stretch of water14.

To this end, and as shown inFIGS. 1 and 4, the elongate element12is partially wound helically around the drum42by forming a plurality of turns70tight on the circumferential casing50.

Thus, the elongate element12has an untensioned upstream segment72extending in a chain between the storage assembly22and the drum42and a tensioned downstream section74extending from the drum42to the stretch of water14, preferably vertically through the wellbore28.

To ensure effective unwinding of the elongate element12, the drive mechanism44comprises, according to the invention, at least one movement assembly80of each turn70following a direction of movement D forming a non-zero angle with a local axis C-C′ of the turn70at the contact region82of the turn70on the movement assembly80.

It further comprises an activation assembly83for each movement assembly80.

Preferably, the direction of movement D forms an angle of at least 10°, advantageously of at least 45°, and more preferably at least 80° with the local axis C-C′.

Furthermore the direction of movement D forms an angle less than 80°, in particular less than 45°, and preferably substantially zero with an axis parallel to the central axis B-B′ passing through the contact region82.

Thus, in the example shown inFIGS. 3 and 4, the direction of movement D is parallel to the central axis B-B′.

As shown inFIG. 2, the drive mechanism44comprises a plurality of parallel movement assemblies80distributed angularly about the axis B-B′.

The angular extent of each movement assembly80about the axis B-B′ is less than 45°.

At least one movement assembly80advantageously extends substantially along the entire width of the drum42between the flanges45,46.

In the example shown inFIGS. 2 to 4, each movement assembly80comprises an endless organ82movable in the direction of movement D and a setting in motion assembly84of the endless organ82.

The endless organ82and its setting in motion assembly84are carried by the drum42and are movable in co-rotation with the drum42.

Referring toFIG. 4, each endless organ82is closed on itself. In this example, it comprises a closed chain86and a plurality of pads88to receive the turns70, mounted on the chain86.

Each pad88delimits a channel89to receive a turn70. The channel89extends along an axis that forms a non-zero angle with the direction of movement D. Preferably, in the example shown in the Figures, this angle is greater than 45°, especially greater than 80°.

When the turn70is received in the channel89, the channel89defines a contact region of the turn70. The turn70then has a local axis coincident with that of the channel89measured at the contact region.

The endless organ82thus has a linear outer axial section90intended to define partially the circumferential casing50for winding the elongate element12, and a linear inner section92for rewinding.

The inner section92and outer section90are connected together by curved end sections94surrounding the setting in motion assembly84.

The endless organ82thus has an elongated shape in the direction of movement D.

In the example ofFIG. 3, the outer section90is received in an outer channel58and the inner section92is received in an inner channel62,64located opposite the outer channel58receiving the outer section90.

The setting in motion assembly84comprises, for each movement assembly80, an active drive wheel96, and a passive driven wheel98. It further comprises a bevel gear100engaged with the drive wheel96and a peripheral satellite102intended to interact with the activation assembly83.

The wheels96,98have an outer toothing to engage with the endless organ82around the curved sections94. They are each carried by the drum42and are mounted to rotate about an axis D-D′ perpendicular to the direction of movement D.

The bell gear100comprises its own gear able to transmit a rotational movement of the satellite102about an axis substantially parallel to the central axis B-B′, to the active drive wheel96to drive its rotation about the axis D-D′.

In this example, each satellite102projects axially along a lateral flange45of the drum42.

The active drive wheel96is thus able to move the endless organ82around the wheels96,98. This movement causes a translation of the outer section90along the direction D in a first direction, and an opposite translation of the inner section92along the direction D in a second direction opposite to the first direction.

The activation assembly83is adapted to interact with each satellite102to cause the rotation of the satellite102during the rotation of the drum42.

In this example, the activation assembly83comprises a ring gear104mounted fixed in rotation along a flange45of the drum42.

Thus, the rotation of the drum42about the central axis B-B′ causes a rotational movement of each satellite102in the ring gear104, and hence a rotational movement of the satellite102about its axis.

A method of laying an elongate element12in a stretch of water14using the laying installation10is described below.

Initially, the elongate element12stored in the storage assembly22is brought to its place of laying by the surface assembly20.

It is then unwound from the storage assembly22and wound around the circumferential casing50of the drum42to form a plurality of helical turns70.

Each turn70is placed locally in contact with each movement assembly80in a contact region. In this example, each turn70is successively received in a channel89of a pad88that guides the turn70along a local axis C-C′ in the region of contact on the movement assembly80.

The elongate element12has then an untensioned upstream section72which extends between the storage assembly22and a first lateral edge of the circumferential casing50located adjacent to a first flange46.

The turns70extend successively to a second lateral edge of the circumferential casing50located adjacent to a second flange45.

The elongate element12also has a downstream section74extending vertically from the second lateral edge to the stretch of water14, preferably through the wellbore28.

The drive unit43is activated to lower the elongate element12by rotating the drum42about the axis B-B′.

This rotation causes the unwinding of an increasing length of the elongate element12from the storage assembly22, and the insertion of a correspondingly increasing length of the elongate element12in the stretch of water14.

The rotation of the drum42automatically activates the setting in motion assembly84of each endless organ82.

In particular, each satellite102is rotated in the ring gear104, causing rotation of the satellite about its axis102. This rotational movement is transmitted to each drive wheel96through the bevel gear100.

The rotation of the drive wheel96in turn causes rotation of the driven wheel98and movement of the outer section90of the endless organ82in the direction of movement D.

As the direction of movement D forms a non-zero angle with the local axis of each turn70in the region of contact on the movement assembly80, the turn70shifts along the direction of movement D, in the direction going from the first flange46, in the vicinity of which is the upstream section72, towards the second flange45in the vicinity of which is the downstream section74.

Thus, the downstream section74is retained very effectively on the circumferential casing50by the capstan effect. Furthermore, the movement of each turn70along the direction of movement D results in a gradual sliding of the turns70from one flange to the next, thus avoiding a blockage of the elongate element12on the drum42.

The unwinding of the elongate element12thus occurs without difficulty, using a drive mechanism44of simple construction, and preferably activated directly by the rotation of the drum42.

The laying device24is thus particularly effective, while having a minimal footprint.

The laying device24of a second laying installation120according to the invention is shown inFIGS. 6 and 7.

Unlike the laying device24of the first installation10, the device24comprises a radial movement mechanism122with at least one movement assembly80.

In the example shown inFIG. 7, the mechanism122is adapted to move locally a region124of the outer section90of the endless organ82radially away from the central axis B-B′.

In this example, the mechanism122comprises a support plate126mounted to swivel about an axis E-E′ perpendicular to the direction of movement D, and an actuator128for radial displacement of a region of the plate126.

The plate126is engaged under the outer section90. The actuator128is arranged under the plate124, while the plate124is interposed between the actuator128and the outer section90.

Thus, upon movement of the outer section90in the direction D, the actuator128is capable of being activated to lift locally the region124and cause a slight local inclination of the outer section90in order to ensure a more effective sliding of the turns70towards the flange45.

The laying device24of a third laying installation150according to the invention shown inFIGS. 8 and 9, differs from the device24of the second laying installation120in that the mechanism122has no support plate124.

The mechanism122thus comprises a plurality of actuators152arranged parallel to each other in the direction of movement D to interact radially with the outer section90. The actuators152are selectively driven to successively raise successive regions of the outer section90away from the central axis B-B′.

It follows from the description and figures that the movement assembly80is rotatably connected to the drum42.