EP1204807B1 - Device and method for maintaining and guiding a riser, and method for transferring a riser onto a floating support - Google Patents

Abstract

An apparatus for holding and guiding a floating riser relative to a floating support. The apparatus includes a guidance mechanism secured to the floating support for enabling the riser to rotate about a horizontal axis perpendicular to a longitudinal axis of the riser; and for enabling the riser to slide longitudinally along the longitudinal axis and lateral displacement of the riser to be guided in a horizontal plane perpendicular to the longitudinal axis of the riser. The guidance mechanism includes friction pads mounted on a pad support for enabling the pads to pivot. The pads preferably cooperate with wheels such that the wheels bear against the riser and enable it to slide, and the riser comes to bear against the pads only when the wheels are moved away under the effect of lateral displacements of the riser.

Description

The present invention generally relates to the field of connections bottom-surface of the type comprising a vertical submarine pipe, called riser, connecting the bottom of the sea to a floating support installed in area.

As soon as the water depth becomes important the exploitation of production fields, in particular oil fields, is carried out in general from floating supports. This floating support comprises in anchoring means in order to remain in position despite the effects of current, winds and swell. It also usually includes means storage and processing of oil and means of unloading to oil tankers. They come to regular interval to perform the removal of production. The name of these floating barge type supports is the Anglo-Saxon term "Floating Production Storage Offloading" (meaning "floating medium" Storage, Production and Offloading ") hereafter abbreviated as "FPSO". Many variants have been developed such as SPARS, long vertical floating cigars held in position by anchors catenaries, or the TLPs ("Tension Leg Platform"), platforms to tense anchor lines, said lines being generally vertical.

Wellheads are often spread over the entire field and production lines, as well as water injection lines and control cables, are deposited on the seabed in direction of a fixed location, on the vertical side of which the floating support is positioned on the surface.

Some wells are located vertically on the floating support and the interior of the well is then accessible directly from the surface. In this case the wellhead equipped with its "Christmas tree" can be installed in surface, on board the floating support. We can then perform, from a derrick installed on said floating support, all the drilling operations, well production and maintenance throughout the life of the well said well. This is called the dry wellhead.

In the case of SPARs and TLPs, dry well heads are gathered in a limited area of the platform, in which the derrick is movable to be positioned vertically to each of the wells to carry out drilling operations or maintenance operations of the well throughout the life of the field.

The drilling rig is a tall structure that can reach 60m and possessing a lifting capacity that can exceed 500 tonnes, the means necessary to move it from one well to another and to keep it in position during well operations lead to complex and expensive structures.

To keep the riser equipped with its dry wellhead in position substantially vertical it is appropriate to exert a pull up which can be applied either by a cable tensioning system using winches or hydraulic cylinders installed on the floating support, using floats distributed along the riser and installed at various depths, again by a combination of both.

Patent FR 2,754,011 describing a barge and a system is known from guide for riser, the latter being equipped with floats.

SPARS and TLPs are also equipped with a multiplicity of risers subtended by floats and held in position by guidance systems.

In FPSOs, risers rise to the surface in a cavity central floating support called "wellbay" or bay drilling. The cavity crosses the hull vertically from side to side on a height of about thirty meters, with a draft of about twenty meters; she is in general installed at the floating support axis, equidistant from its ends, because this is the area where the amplitudes of the movements and accelerations is the weakest when the ship is subject to the phenomena of roll, pitching and yawning.

The water depth of some oilfields exceeding 1,500m and up to 2,000 to 3,000m, the weight of the risers on such heights require their holding in position, vertical forces reach and exceed several hundred tons. We use elements type of buoyancy device installed at various levels on the connecting risers the ultra-deep sea surface (1000-3000m).

The floats concerned are large with, in particular a diameter greater than 5m, and a length of 10 to 20m and possess unit buoyancy up to 100 tonnes.

The float and the conduct are subject to the effects of swell, current, but being connected to the FPSO at the surface, are also indirectly subject to the effects of wind. This results in lateral movements and vertical lines of up to several meters riser-float-barge, especially in the area prone to swell.

To prevent the risers from interfering with each other and interfering with the hull of the floating support, said risers are separated from each other by several meters and also several meters from the walls of the wellbay, this which leads to wellbays up to 80m in length and 20m in length width, on FPSO barges up to 350 m long, 80 m wide width and having a height at the level of the plating up to and exceed 35 m. Such barges have a deadweight tonnage which may reach and exceed 500,000 dwt.

These movements of the risers generate differential efforts between the riser and the solid support guidance systems floating.

The range of displacements and the very high level of risers, lead to the design of guiding systems capable of to resist not only the extreme conditions but also the cumulative fatigue and wear phenomena over the life of the facilities, which may exceed 25 years.

The present invention relates to the guidance of risers within the generally central cavity in production position or in a position where drilling operations as well as heavy maintenance operations wells are made, ie from a fixed derrick relative to to the floating support, or on the means of transfer of the riser between these various positions.

The present invention also relates to the transfer of risers to within the generally central cavity from their production position to a position where drilling operations as well as heavy well maintenance operations are carried out, that is to say from a fixed derrick with respect to the floating support.

Well drilling is carried out at the main axis of the derrick, through a riser called "drilling riser", whose function is to guide the drill rods and contain the sludge back from the well being pierced. This riser of drilling is assembled from unit lengths up to 50m, the assembly being lowered in step by step, as and when assembly said riser. At the end of the drilling, the portion of the riser corresponding to the slice of water is disconnected from the well at sea level and then directed towards a garage position after its length has been shortened by disassembly of one or two unit lengths. By doing so, the riser drilling remains hung, its lower end being located 50-100 m the bottom.

The production riser can then be assembled in the same way step by step until it reaches the entrance to the well. The floats are installed in the upper part as and when laying, then the base of the production riser is finally connected to the well. The well is then equipped various casings of production and "Christmas tree" of the wellhead Dry is set up.

The whole is then transferred to its "slot", production position where it will remain for the entire life of the field except for some maintenance operations where it will be necessary to return said riser to the axis head of the derrick to perform heavy operations.

Raising guide means are known relative to the support floating. But these guidance systems most often involve Cable tensioning systems that are difficult to implement (GB 2170240 or US 4231429). Other systems have been proposed which are not versatile but specific to a position of the riser on the support floating, especially at the axis of the derrick for drilling risers. For the drilling, the risers are in place for a limited time such as 10 to 45 days, so that the wear of guiding devices is not really critical unlike the production risers that are installed for several years and require wear-resistant guiding systems. Thus, in US 4,617,998 and US 4,616,708, a device for maintenance and guidance for drilling riser that combines a system of cable tensioning with runners on which the drilling riser comes in support, and that does not resist wear in the long run.

Cable tensioning guidance systems make the transfer of the riser from one position to another within the central cavity (wellbay) long and difficult to achieve, particularly with regard to moving from the production position to the axis position from the derrick.

An object of the present invention is to provide a device for maintaining and guiding a riser, in particular a floating riser, relative to floating support, simple to implement, and that can be useful whatever the position of the riser, especially when the riser is at its position of production or in drilling or maintenance position at the axis of the derrick; or when transferring the riser from its production position to the axis of the derrick.

This device must allow relative movements of the support floating and riser, so as to withstand routine fatigue corresponding to lateral loads of up to 10 tonnes, and occasional extreme efforts corresponding to loads that may to reach 100 tons, or even 200 tons.

The device must be able to authorize, not only longitudinals substantially vertical up to 5 meters, if we consider that the relative movements between the floating support and the risers in normal operation, but also accept extreme shifts corresponding to the complete deballasting of the floating support or its maximum ballast, which corresponds to a total stroke that can reach 15 to 20 meters.

In addition, for operations carried out at the axis of the derrick, the riser must stay substantially coaxial with the axis of the derrick.

Another object of the present invention is to provide a device for holding and guiding riser in production position that resists wear over a long period, especially over several years.

Another object of the present invention is to provide a device for guiding which allows the transfers of the riser in a position to a other within the central cavity (wellbay) are simple to carry out and therefore can be done safely.

a) la rotation dudit riser autour d'un axe horizontal perpendiculaire à l'axe longitudinal dudit riser, dans la limite d'un cône de demi-angle au sommet inférieur ou égal à 10°, ledit axe horizontal et ledit sommet du cône étant situés sensiblement au centre du riser et au niveau du plan médian de la zone où sont situés lesdits moyens d'articulation le long de l'axe longitudinal, et

b) lesdits coulissements dudit riser selon son axe longitudinal et ledit guidage des déplacements latéraux dudit riser dans un plan sensiblement perpendiculaire audit axe longitudinal du riser, et

   lesdits moyens d'articulation comprennent :

• des premiers patins de frottement étant montés sur un support de patins permettant le pivotement desdits patins autour d'un axe perpendiculaire audit axe longitudinal dudit riser, et
• lesdits premiers patins coopérant avec des seconds patins de frottement, ou de préférence des roulettes, de sorte que lesdits seconds patins ou lesdites roulettes sont en appui su ledit riser, et permettent son coulissement, et ledit riser ne vient en appui sur lesdits premiers patins que lorsque lesdits seconds patins ou lesdites roulettes se déplacent sous l'effet des déplacements latéraux dudit riser. On comprend que les déplacements latéraux du riser, notamment dans une direction radiale, sont engendrés par les efforts relatifs entre support flottant et riser.

To do this, the present invention provides a device for holding and guiding a riser, in particular a floating riser, with respect to a floating support comprising guiding means for sliding said riser along its longitudinal axis and guiding its lateral movements. in a horizontal plane perpendicular to said longitudinal axis of the riser, in particular in a radial direction. The device according to the invention comprises hinge means integral with said floating support allowing:

a) the rotation of said riser about a horizontal axis perpendicular to the longitudinal axis of said riser, within the limit of a cone of half-angle at the vertex less than or equal to 10 °, said horizontal axis and said apex of the cone being located substantially in the center of the riser and at the median plane of the zone where the said articulation means are situated along the longitudinal axis, and

b) said sliding of said riser along its longitudinal axis and said guiding of the lateral displacements of said riser in a plane substantially perpendicular to said longitudinal axis of the riser, and

said articulation means comprise:

• first friction pads being mounted on a support of pads allowing the pivoting of said pads about an axis perpendicular to said longitudinal axis of said riser, and
• said first pads cooperating with second friction pads, or preferably casters, so that said second pads or said casters are supported on said riser, and allow its sliding, and said riser bears on said first pads that when said second pads or said wheels move under the effect of lateral movements of said riser. It is understood that the lateral movements of the riser, in particular in a radial direction, are generated by the relative efforts between floating support and riser.

"Longitudinal axis of the riser" means the vertical axis when the riser is in the rest position, that is to say not subject to movements related to the bustle of the sea.

In the guide holding device of the present invention, said second pads or said wheels are in permanent support on the riser, but do not take up the full load applied by the riser. The device according to the invention is indeed designed to withstand variables in the horizontal plane with at least two levels of friction and different wear. In the rest position, said first pads are in withdrawal relative to said second pads or said rollers. Said seconds skates or rollers preferably provide guiding of the riser subjected to current efforts of light loads of about 10 tons. said first pads come into operation and provide guidance when the riser is subject to heavy loads under extreme conditions of implementation. in particular up to 100 tonnes, or even 200 tonnes, and that second pads or said rollers are moved radially under the effect of his heavy charges.

This double level of friction and wear of the skates and castors makes the holding and guiding device of the invention particularly appropriate when the riser is in the production position, that is to say in the where the operating life requires guiding systems that are resistant to wear over a long time.

Said first pads have a bearing surface on said riser which preferably has a curvature complementary to that of the riser.

In one embodiment, said first pads can rotate relative to an axis integral with said support skates.

In another embodiment, said pads are fixed by relative to said skate support and said skate support is pivotable by report to said floating support to enable said pivoting of said first skids about an axis perpendicular to said longitudinal axis of said riser.

More particularly, said first pads are fixed on a tubular element enveloping said riser coaxially with said riser, said tubular element being mounted on a ball joint allowing said pivoting and said rotation respectively said pads and said riser.

According to the device of the invention, said ball may be a stop laminated within which is embedded said tubular member.

Advantageously, said second pads or preferably said casters are mounted on axes perpendicular to the vertical axis of the riser, the axis of said second pads or preferably said wheels being capable of moving in translation along an axis perpendicular to the axis longitudinal of said riser, in a radial direction.

Preferably, said first pads are distributed symmetrically around said riser, and comprise at least three pads located, preferably again, at the same level along the longitudinal axis of said riser.

Preferably, said second pads or preferably said casters are arranged symmetrically around said riser with respect to its longitudinal axis and with at least three wheels, whose axes of rotation are located, preferably still, substantially in the same plane.

In one embodiment, said first pads are mounted on an axis located substantially in the same horizontal plane as the axis of said casters and said first pads and said casters are arranged successively and symmetrically around said riser alternately.

In another embodiment, said first pads and said casters are arranged in staggered rows, their respective pivoting axes and rotation being located at different levels respectively along the axis longitudinal of said riser.

More particularly, said first pads are arranged on at at least two different levels along said longitudinal axis of said riser, and said levels are arranged symmetrically with respect to a plane horizontally corresponding substantially to the median plane of the zone where located said articulation means along the longitudinal axis.

According to another variant embodiment, the axes of rotation of the casters are arranged on at least two different perpendicular planes said longitudinal axis of said riser, and said planes are arranged symmetrically with respect to a corresponding horizontal plane substantially to the median plane of the zone along the longitudinal axis of the riser where are located said articulation means.

According to another variant embodiment, said first skates can be located on two different levels along the longitudinal axis said riser, an upper level and a lower level and said rollers are located above and above the said upper level inferior.

According to another variant, said first pads are located on two different levels, a higher level and a lower level, and said casters are located between said levels.

The holding and guiding device according to the invention can be in place on the floating support to maintain and guide undit riser in its production position, or it can be connected to transfer means undir riser from its production position towards the axis of a derrick of drilling. In both cases, said articulation means are preferably disposed at the junction floor between said riser and said support, located between the floating support deck and the water level.

More preferably, the top of the cone of half-angle at the top, less than 10 °, is located substantially at the level of the said floor of junction.

A holding and guiding device according to the invention may also be set up on said floating support to maintain and guide undit riser in operating position in a derrick installed on said support floating, more precisely to the axis of said derrick.

At the axis of the derrick, one can put in place a device of maintenance and guide according to the invention, at different levels along the axis longitudinal of the riser ZZ '. According to its positioning along the axis longitudinal dimension, the dimensions of the skids and castors will be adapted function of the forces to be transmitted and the relative movements of the riser, tolerable with respect to the floating support.

We can first put in place the device according to the invention level of the junction floor of the riser with the floating support, that is to say at an intermediate position between the deck of the floating support and the level of the water. In this case, we can use the same type of device in position of production, or during the transfer of the riser from its position of production up to the axis of the derrick. The wheels or second skates are then dimensioned to support current efforts corresponding to loads up to 5 tonnes, and said first runners of extreme forces corresponding to loads of up to 50 tonnes.

It is also possible to position a device according to the invention at at least one of the two levels P ' ₁ and P' ₂ , preferably respectively above and below said junction floor of the riser relative to the floating support, the levels P ₁ and P ' ₂ being located at different levels of the wall of the cavity of the floating support, but sufficiently spaced to maintain said riser substantially coaxial with the axis of the derrick, and allow lateral movements of the riser such as the axis of the riser does not deviate more than 5 ° from the axis of the derrick; preferably not more than 2 °.

The present invention therefore relates to a device comprising said hinge means comprising said first pads cooperating preferably with wheels, located on a first level P ' ₁ and a second level P' ₂ along the wall of the central cavity floating support, respectively above and below the level P _{0 of} said junction floor between the riser and said floating support.

In order to limit the current and extreme forces transmitted at planes P ' ₁ and P' ₂ to loads of 10 and 100 tons respectively, the planes P ' ₁ and P' ₂ are advantageously spaced at the most, in particular by at least 5, preferably at least 10 meters.

Insofar as the height of the wall of the cavity of the floating support is approximately 30 meters, its draft being approximately 10 meters, and also to the extent that the plane P ' ₁ is located above the level water and slightly below the deck level of the floating support, it is possible that the lower plane P ' ₂ is below the water level.

In this position at the axis of the derrick, said hinge means can be fixed inside a collar held in place around the riser by cables connected by a tensioning system to the wall of the cavity of said floating support at least one of said levels P ' ₁ and P' ₂ .

In another embodiment, said articulation means comprising said first pads cooperating preferably with said casters, are located at the end of an articulated arm system comprising hydraulic cylinders.

Advantageously, the system of articulated arms can move between a closed position and an open position, so that in position closed, said articulation means preferably comprise said casters which are in contact with said riser, and in the open position, it allows the passage of a float adapted to said floating riser, said means hinge preferably said wheels remaining in contact with said float.

Advantageously, each of the articulated arms of the same plane P'1 or P'2 can be adjusted in length, which allows to create a misalignment a known value between the axis of the riser and the axis of the derrick.

The present invention also relates to a method of maintaining and guiding a floating riser with respect to a floating support allowing said riser to slide along its longitudinal axis ZZ 'and guiding its lateral movements in a horizontal plane XX ', YY' perpendicular to said riser, using at least one holding device and guide according to the invention.

The present invention also relates to a method of transfer on a floating support of a riser from its position of production to its position within a drilling rig. According to the present invention, said riser is moved into said cavity of a support floating, by moving said device for holding and guiding the riser by relative to the floating support according to the invention, itself integral with said riser.

Advantageously, the floating support comprises a cavity center comprising a plurality of compartments at the end of which said risers are in the production position, said compartments communicating with a central channel, at the end of which is located a drilling derrick, said compartments being arranged transversely with respect to said central channel.

Advantageously, said compartments and said central channel comprise a joining floor between said riser and said support floating on each bank defining a continuous channel of width substantially constant.

In a particular embodiment, said joining floor is integral with the wall of the cavity at an intermediate level between the bridge of the floating stand and water level.

Preferably, the floating support comprises transfer means said risers between their production position at the end of compartments and the position of the derrick, said transfer means to move a said riser along said connecting floor in cooperating with said holding and guiding device ensuring the junction with said riser and said floating support at said floor junction.

According to an alternative embodiment, said transfer means are fixed and secured to said floating support.

In particular, said transfer means comprise a set winches and cables connecting said winches to said riser.

Advantageously, said transfer means comprise a carriage movable along said compartments and said channel.

Advantageously again, said joining floor is equipped with guide rails for moving said transfer means or said riser, especially if said transfer means are stationary, along said compartments and said central channel.

• la figure 1 est une vue de dessus et en plan du riser et du support flottant avec sa cavité centrale, associée à une vue en coupe du derrick de forage à un niveau correspondant au niveau +10m par rapport audit plancher de jonction ;
• la figure 2 est une vue en plan selon la figure 1, comportant, de plus, les moyens de transfert du dispositif de maintien et guidage de riser selon l'invention, depuis sa position de production jusqu'à l'axe du derrick de forage ;
• la figure 3 est une représentation schématique des degrés de liberté de rotation autorisés par le dispositif de guidage selon l'invention, et correspondant au mouvement possible du riser en position de production sur son slot et durant toute la phase de transfert vers l'axe du derrick ;
• la figure 4 est une représentation des degrés de liberté de rotation et de translation autorisés par le dispositif de guidage selon l'invention, lorsque le riser se trouve en position à l'axe du derrick. Dans cette configuration le riser est guidé sur au moins deux niveaux distincts, au niveau du plan P'₁ et au niveau du plan P'₂, lesdits plans étant suffisamment espacés ;
• la figure 5 est une vue de côté d'un dispositif de guidage selon l'invention, comportant une multiplicité de roulettes et de patins installés en alternance tout autour dudit riser, les patins et les roulettes étant situés sur un même plan ;
• la figure 6 est une variante d'un dispositif selon l'invention, en vue de côté un riser de production et en coupe, le dispositif de guidage est muni d'une articulation de type butée lamifiée et présente une combinaison de roulettes et de patins installée sur un élément tubulaire sensiblement coaxial à l'axe dudit riser, les patins et les roulettes étant situés sur des niveaux différents le long de l'axe longitudinal ZZ' ;
• la figure 7 est une vue de dessus d'un dispositif selon l'invention reposant sur le plancher de jonction sur lequel est figuré un canal permettant à l'ensemble d'être déplacé vers l'axe du derrick ;
• la figure 8 est une vue de côté d'un dispositif de guidage selon l'invention associé à un riser en position d'opération à l'axe du derrick, et monté sur la paroi de la cavité ou baie de forage (wellbay);
• les figures 9 et 10 sont des vues de dessus détaillant un collier qui sert de support à des moyens d'articulation représentés dans le plan des patins, qui est maintenu en tension par trois ou quatre câbles reliés à un système de tensionnement ;
• les figures 11 et 12 sont des vues de côté d'un riser en position d'opération à l'axe du derrick, les dispositifs selon l'invention étant montés sur des systèmes de bras articulés munis de vérin hydraulique ;
• la figure 13 représente une vue de côté du riser muni d'un dispositif de maintien et de guidage comportant des moyens d'articulation 3 selon l'invention, relié à des moyens de transfert 12 en cours de transfert dans le canal central 24 de la cavité du support flottant.

Other features and advantages of the present invention will appear on reading the detailed description of certain embodiments which will follow, with reference to the following figures in which:

• Figure 1 is a top and plan view of the riser and the floating support with its central cavity, associated with a sectional view of the drill rig at a level corresponding to the level + 10m with respect to said junction floor;
• FIG. 2 is a plan view according to FIG. 1, comprising, in addition, the transfer means of the riser holding and guiding device according to the invention, from its production position to the axis of the drill rig. ;
• FIG. 3 is a schematic representation of the degrees of freedom of rotation allowed by the guide device according to the invention, and corresponding to the possible movement of the riser in the production position on its slot and during the entire transfer phase to the axis of the derrick;
• Figure 4 is a representation of the degrees of freedom of rotation and translation permitted by the guide device according to the invention, when the riser is in position to the axis of the derrick. In this configuration the riser is guided on at least two distinct levels, at the plane P ' ₁ and at the plane P' ₂ , said planes being sufficiently spaced;
• Figure 5 is a side view of a guide device according to the invention, comprising a plurality of casters and pads alternately installed all around said riser, the pads and wheels being located on the same plane;
• FIG. 6 is a variant of a device according to the invention, in view of a production riser and in section, the guiding device is provided with a laminated stop-type articulation and has a combination of wheels and skids. installed on a tubular element substantially coaxial with the axis of said riser, the pads and the rollers being located on different levels along the longitudinal axis ZZ ';
• Figure 7 is a top view of a device according to the invention resting on the junction floor on which is shown a channel allowing the assembly to be moved towards the axis of the derrick;
• Figure 8 is a side view of a guide device according to the invention associated with a riser in the operating position to the axis of the derrick, and mounted on the wall of the cavity or wellbay;
• Figures 9 and 10 are top views detailing a collar which serves to support hinge means shown in the plane of the pads, which is held in tension by three or four cables connected to a tensioning system;
• Figures 11 and 12 are side views of a riser in the operating position to the axis of the derrick, the devices according to the invention being mounted on articulated arm systems provided with hydraulic cylinder;
• FIG. 13 represents a side view of the riser provided with a holding and guiding device comprising articulation means 3 according to the invention, connected to transfer means 12 being transferred in the central channel 24 of the cavity of the floating support.

FIG. 1 shows a view from above and in plan the joining floor 4. The floating support comprises a cavity 23 comprising a plurality of compartments forming channels 23 ₁ and a central channel 24, said compartments 23 ₁ and said channel central 24 being of longitudinal shape and substantially constant width and having a continuity between said positions of the riser in the production position (slot) and the axis of the derrick. These compartments 23 ₁ are arranged transversely with respect to the central channel 24 which makes it possible to move a riser on the joining floor 4 between its production position 11 at the end of said compartment 23 ₁ and the position at the axis of the derrick 14 to the end of said central channel. Ten production positions 11 have been represented but only one is equipped with its riser 1 equipped with a guiding device 3 secured to the joining floor 4.

FIG. 5 shows an embodiment of the device according to the invention, in which the runners 5 and the rollers 9 are located on the same plane, and the pads pivot around a hinge axis 6 secured to a support skids 7, fixed on the floating support 2.

a) les déplacements du riser parallèlement à son axe longitudinal ZZ', et

b) les mouvements angulaires selon des axes XX' et YY' situés dans un plan horizontal, limités au cône de demi-angle au sommet ϑ, le demi-angle dudit cône étant, selon l'invention, inférieur à 10 degrés ;

c) des déplacements latéraux très limités dans le plan des axes XX' et YY'.

In FIG. 5, the production riser is equipped with a guiding device 3 according to the invention allowing:

a) the movements of the riser parallel to its longitudinal axis ZZ ', and

b) the angular movements along axes XX 'and YY' situated in a horizontal plane, limited to the cone of half-angle at the apex θ, the half-angle of said cone being, according to the invention, less than 10 degrees;

c) very limited lateral displacements in the plane of axes XX 'and YY'.

The guiding device shown in FIG. 5 consists of a plurality of casters and pads alternately installed all around said riser, the guiding device shall comprise at least three casters and three skids arranged regularly or not around said riser.

The rollers 9, one of which is shown on the right side of the 5, are secured by means of wheels carriers 25, a base 22, itself secured to the junction floor 4. The axis 10 of said wheel is integral with a cylindrical part 26 whose bore internal is eccentric with respect to the axis of said cylindrical piece. This cylinder 26 is surrounded by a layer of elastomer 27 in the form of a ring, the assembly being held in position in the wheel carrier 25 to 28. Each of the rollers 9 is supported by a pair of roller supports 25 and ring 27, installed on the cylinder 26 of both sides of said wheel. The device thus described: - (a) allows to adjust, thanks to the eccentric assembly 10-26, the position of the wheel relative to the outer wall of the riser; - (b) allow light displacements of the eccentric assembly, when a load is applied by Rinse it on the wheel, in the direction YY ', to the right. A result similar can be obtained by a spring system.

The pads 5, one of which is shown on the left of FIG. 5, are consisting of an antifriction block 29 whose face facing the riser presents a curvature corresponding to that of said riser. The skate is supported by an articulation of axis 6, spherical ball-type or lamified abutment, integral 7. Laminated abutments are materials sandwich type composites consisting of separate elastomer layers by metal reinforcements and allow angular displacements and which may be important and whose value can be adjusted by varying the elastomer thicknesses, the number of layers and the provision of metal reinforcements. Such devices are manufactured in particular by Techlam France.

When the riser is in the rest position and no effort is applied by said riser to the guide system, the position of the rollers is adjusted, by means of the eccentric assembly previously described, of in such a way that the blocks 29 of the pads 5 are not in contact with the riser. Thus, when efforts are low, the riser is guided only by the rollers, but as soon as the forces increase, the elastomer ring 26 crashes and allows the roll back; the riser then coming into contact with the pads adjacent to said wheel, said pads transfer then the forces directly to the base 22-1 via the shoe 5, without creating an unacceptable overload on the roulette wheel.

By doing so, the low charges, which apply in 90 to 98% of the time, are transferred entirely through casters, thus with friction and very little wear, whereas the heavy loads, which remain exceptional, are transferred by skates, without risk of damaging the rollers or the surface of the riser.

The removal of the pads compared to the riser is low, for example the order of one centimeter and the thickness of the elastomer ring 106 is calculated in order to allow a corresponding displacement of the axis of the roulette. This thickness can be for example three centimeters.

For example, the efforts encountered over the life of a riser in production position, are in the range of 2 to 5 tonnes for 95% of the time, from 10 to 20 tons out of the remaining 5% with very high load peaks exceptional, corresponding to the 100-year reach and exceed 50 tons.

By proceeding according to the invention, the size is optimized, and therefore the cost casters, the life of which can be significant without having to oversize for extreme situations. The skates are sized for extreme cases and their maintenance can be carried out without difficulty during calm periods when they are not active.

A similar result is obtained by replacing the wheels with said second pads with very low friction low loads. said second skids are then mounted in place of the wheels and fade away in the same way when the load on the riser exceeds one previously fixed value.

FIG. 6 shows a device according to the invention in which the pads 5 and the rollers 9 are located on different levels on along the longitudinal axis ZZ 'of the riser, and the pads are fixed with respect to a tubular element 7, itself pivotable relative to the support floating.

Figure 6 which is a variant of Figure 5 shows in side view a production riser 1 equipped with a guiding device 3 comprising a skate support consisting of a tube 7 coaxial with the longitudinal axis ZZ 'of the riser 1 and having symmetrically with respect to the plane XX '/ YY', a plurality of rollers 9 provided with their eccentric assembly 10-26 and the elastomer layer 27 in the form of a ring, in contact with the said riser. The friction pads 5 are installed in a different plane, advantageously close to the plane XX '/ YY' and are not in contact with said riser. The entire guide is symmetrical with respect to the plane XX '/ YY' and is secured to the junction floor 4 by a hinge 8 of laminated abutment type comprising layers of elastomer 30 and reinforcements 31 formed of metal sheets formed according to portions of spheres of center ○ corresponding to the apex of the rotation limit cone. The kneecap lamified 8 then allows the rotations of the guiding device 3 around the axes XX 'and YY' and keeps all casters in contact with the 1. When efforts become important, the rollers 9 clear and the pads then come into direct contact with the wall of the riser. The transmission of the forces between riser and junction floor then becomes substantially symmetrically with respect to the plane XX '/ YY' whatever the value of the angle θ formed by the axis of the riser with the vertical, as shown in Figure 5.

• de quatre roulettes 9 en contact avec le riser,
• du tube support 7 par l'intermédiaire d'un ensemble excentrique 10-26 non représenté,
• de quatre patins 5 en léger retrait par rapport au riser.

FIG. 7 is a view from above of a guiding device similar to that of FIG. 6 showing the guiding device 3 of the riser 1 at the position corresponding to the slot 11 and resting on the joining floor 4. Said joining floor 4 defines a channel 23 ₁ allowing the riser-guiding device assembly to be moved towards the axis of the derrick 14. The guiding device consists of:

• four wheels 9 in contact with the riser,
• of the support tube 7 via an eccentric assembly 10-26, not shown,
• four skates 5 in slight withdrawal from the riser.

For the understanding of the drawing, the pads 5 are represented here between two wheels 9 while in Figure 6 they are represented in vertical alignment with said rollers. The tube 7 is connected to the support 22 through the laminated abutment hinge 8 of FIG. 6.

In Figures 8, 11 and 12 which show a riser in the operating position to the axis of the derrick, associated with sections detailing the guide devices according to the invention, located in planes P ' ₁ , and P' ₂ , the derrick is located above the deck 21 of the floating support and is integral with the latter. The various guide elements and the junction floor 4 are integral with the wall 20 of the cavity (wellbay).

a) soit rester en place pendant toute la durée des opérations à l'axe du derrick, auquel cas les roulettes seront en mouvement permanent lors des déplacements du riser selon l'axe ZZ', mais aucun effort latéral selon les axes perpendiculaires XX' et YY' ne sera transmis par ce guidage à la structure delà barge, car les efforts sont intégralement transmis à ladite structure entre les plans P'₁ et P'₂ : le dispositif de guidage 3 peut alors être considéré comme inactif, car ne participant pas à la stabilisation latérale ;

b) soit être démonté pendant toute la durée des opérations à l'axe du derrick, puis remis en place pour le transfert de retour vers la position de slot de production 11.

The guiding device 3 comprising hinge means according to the invention of the riser 1, in position P ₀ corresponding to the joining floor 4, for the transfer between the slot 11 and the axis 14 of the derrick 13 can:

a) remain in place for the duration of the operations at the axis of the derrick, in which case the rollers will be in constant movement during the movements of the riser along the axis ZZ ', but no lateral force along the perpendicular axes XX' and YY 'will not be transmitted by this guidance to the structure of the barge, because the forces are integrally transmitted to said structure between the planes P' ₁ and P ' ₂ : the guide device 3 can then be considered inactive because it does not participate at lateral stabilization;

b) be removed for the duration of the operations at the axis of the derrick, and then put back in place for the return transfer to the production slot position 11.

In Figure 8, the guide device according to the invention is associated with two guide collars equipped with pads and wheels. In the plane P ' ₁ , the collar is held by a system of hydraulic cylinders secured to the wall of the cavity or wellbay and connected to said collar, either directly or by means of live cables. The left cylinder is connected via a pulley itself secured to the wall of the wellbay. In the plane P ' ₂ , the collar is held in place by a system of winches integral with the wall of the cavity or boring and connected to said collar by means of live cables. The left winch is connected directly to said collar, the right winch is connected via a pulley itself integral with the wall of the cavity or wellbay. A guiding device according to Figure 6 is present at the plane P ₀ .

More precisely in FIG. 8, the guiding device 3 comprising articulation means rests on arms 22 ₁ secured to the junction floor by means of vertical joints 22 ₂ making it possible to fold said arms 22 ₁ as also shown on FIG. Figures 11 and 12, so as to release the passage, for example for the passage of a float.

a) dans le plan P'₁, sur la gauche du dessin, à un vérin hydraulique 17a, solidaire de la paroi 20 de la cavité ou baie de forage (wellbay), le câble étant tourné autour d'une poulie de renvoi, elle-même solidaire de ladite paroi 20 ; sur la droite du dessin à un vérin hydraulique 17a solidaire de la paroi 20 de la cavité ou baie de forage (wellbay) ;

b) dans le plan P'₂ sur la gauche du dessin, à un treuil 17b, solidaire de la paroi 20 de la cavité ou baie de forage (wellbay) ; sur la droite du dessin, à un treuil 17b solidaire de la paroi 20 de la cavité ou baie de forage (wellbay), le câble étant tourné autour d'une poulie de renvoi, elle-même solidaire de ladite paroi 20.

In FIG. 8, the collar 15 is held in position by at least three voltage cables 16, two of which are dimensioned as explained hereinafter in the description of FIGS. 9 and 10. The cables 16 are connected to the collars 15 at the level of FIG. attachment ears and:

a) in the plane P ' ₁ , on the left of the drawing, to a hydraulic cylinder 17a, secured to the wall 20 of the cavity or wellbay, the cable being rotated around a return pulley, it even integral with said wall 20; on the right of the drawing to a hydraulic cylinder 17a integral with the wall 20 of the cavity or wellbay;

b) in the plane P ' ₂ on the left of the drawing, a winch 17b, secured to the wall 20 of the cavity or wellbay; on the right of the drawing, a winch 17b integral with the wall 20 of the cavity or wellbay, the cable being rotated around a return pulley, itself secured to said wall 20.

In FIGS. 9 and 10, the collar 15 is held in tension by three or four cables 16 connected to a not shown tensioning system, characterized in that only two cables 16 have a length L ₁ and L ₂ adjusted in such a way that the axis of the collar along the axis ZZ 'coincides substantially with the axis of the derrick. The other cables are then simply maintained in tension at a voltage level higher than the expected extreme voltage level, corresponding, for example, to 100-year conditions (100 tons). The collar 15 consists of two half-shells connected on one side by a hinge 15 ₁ and on the other side by a locking system 15 ₂ allowing the assembly to be put in place around the riser and removed when the operations are completed.

Fig. 10 is a four-strand version of Fig. 9, in which two of the strands are fitted to a length corresponding to L1 and L2, the other two simply being held in tension. The device according to the invention makes it possible to adjust the coaxiality between the axis of the riser and the axis of the derrick by modifying, in the plane P ' ₁ and / or in the plane P' ₂ , the respective lengths L 1 and L2 dimensional cables. The device according to the invention also allows to maintain the axis of the riser parallel to any given direction, substantially fixed with respect to the axis of the derrick.

In FIGS. 11 and 12, the riser in position at the axis of the derrick is stabilized in the planes P ' ₁ and P' ₂ by a system of articulated arms 18 operated by hydraulic cylinders 19 and supporting at the plane P ' ₁ roller guide associated with friction pads and at the plane P ' ₂ a guide collar similar to the collar defined in Figures 8 and 9. The efforts on the riser in the plane P' ₁ are directed to the right and create an erase of the wheel mounted on a spring system, until the pads come into contact with said riser and transmit directly to the latter the forces corresponding to extreme conditions (centennial conditions), without creating damage at the roller guide or at the riser wall. In this position the axis of the riser deviates angularly very slightly from the axis of the derrick, represented by the angle a, which remains less than 5 °, preferably 2 °.

In Figure 11, the support beam 22, being in the folded position, the guide device 3 is held in a position close to P ₀ by means of two cables 22 ₃ connected to the wall 20 of the wellbay.

In FIG. 12, the lower guide is shown in position open, so as to let the floats pass a production riser in during assembly, during the descent of the various constituent elements. The guides remain in contact with the walls of the float so as to limit the movements of the entire pipe in suspension.

Figure 12 is a side view of a riser 1 being installed at the axis of the derrick. The guidance system of the plane P ' ₂ is identical to that of the plane P' ₁ . Plans P ' ₁ and P' ₂ are spaced eight to ten meters apart.

The riser is being assembled, the whole being lowered with a float 32. The lower guide is shown in the open position, in order to let said float pass while remaining in contact with the walls of said float, so as to limit the movements of the set of suspended pipe.

In this operating phase, the guide device connected to the plane P ₀ , is not yet installed around the riser 1, but will be as soon as the riser is ready to be transferred to its production slot.

In FIG. 12, the articulated arms of the plane P ' ₁ are provided with a device 34, mechanical or hydraulic, making it possible to adjust the length of each arm independently, which makes it possible, by a coordinated variation of the length of each of the arms to create an offset of the apex of the cone defined in Figures 5 and 6, of a known value, in a known direction of the plane P ' ₁ . By advantageously equipping the two planes P ' ₁ and P' ₂ of articulated arms adjustable in length, one can maintain the axis of the riser parallel to any direction substantially fixed with respect to the axis of the derrick.

The holding and guiding device 3 according to the invention comprising articulation means, can be transferred towards the axis of the derrick by means of fixed transfer means relative to the floating support, constituted by winches 12 ₁ and 12 ₄ and cables 12 ₂ shown in FIG.

In FIG. 2 the joining floor 4 comprises means for transferring the riser and a guiding device according to the invention, consisting of winches 12 ₁ connected by cables 12 ₂ to the guiding device 3 moving by simple sliding on the joining floor 4 and being guided in the compartments 23 ₁ by rails 12 ₃ . These two winches make it possible to move the riser-guiding device assembly 3 between the slot position 11 and the central channel axis 24. The rails 12 ₃ facilitate the passage of the device 3 to the right of the adjacent compartments from the production position. departure, to the axis 14 of the derrick. The riser and its guiding device being in position in the central channel 24, the winches 12 ₄ are then connected to the support 22 of the guiding device 3 by two cables 12 ₅ , and the cables 12 ₂ of the winches 12 ₁ are then disconnected. By acting on the winches 12 ₄ , the riser-guide assembly 3 is then transferred from the central position 24 to the axis 14 of the derrick.

The riser can be moved by sliding the support 22 of the guiding device 3 in the form of a washer as shown in FIG. 13. In FIG. 13, tubular elements 22 integral with the support 22 and arranged below the support 22 make it possible to guide the riser in the central channel 24 and between the rails 12 ₃ . Friction pads 22 ₂ arranged below the support 22 and integral with it, allow the support 22 to slide on the joining floor 8 under the action of the winches 12 ₄ and cables 12 ₅ (not shown) when are put into action ..

While remaining in the spirit of the invention, said guiding device can just as easily be left in place. It is then opening, so as to be able to release the riser which is then supported by a second device guiding the same function, but with the difference that the transfer operation being of short duration and being carried out preferably in calm time, said guiding device can be greatly simplified.

The transfer of the slot position to the axis of the riser has been described by means of winch type guiding in the compartments 23 ₁ of the junction floor 4. A similar result can be obtained by a carriage moving on rails to the rail. using means such as manually operated wheels, or by a heat engine or an associated electric motor batteries, or by step advancement systems based on the use of hydraulic cylinders. Said carriage is advantageously equipped with an arm provided with an opening clamp at the end of which a guiding device as described in FIG. 5, or in a simplified version, makes it possible to grip the riser at its slot position 11 at the time of opening of the permanent guiding device, to transfer it to the axis of the drilling derrick where guiding devices as described in Figures 8 to 13 will be implemented ..

Claims (31)

1. Apparatus for holding and guiding a riser (1) relative to a floating support (2), the apparatus including guide means enabling said riser to slide along its longitudinal axis (ZZ') and guiding lateral displacements thereof in a horizontal plane (XX', YY') perpendicular to said longitudinal axis of the riser, the apparatus being characterised in that it comprises joint means (3) secured to said floating support and enabling:

   a) said riser to rotate about a horizontal axis (XX', YY') perpendicular to the longitudinal axis (ZZ') of said riser within the limit of a cone having a half-angle at the apex that is less than or equal to 10°, said horizontal axis and said apex of the cone being situated substantially at the center of the riser and level with the midplane (4) of the zone along the longitudinal axis (ZZ') where said joint means (3) are situated; and

   b) said riser to slide along the longitudinal axis (ZZ') and to be guided in its lateral displacements in a plane (XX', YY') substantially perpendicular to said longitudinal axis of the riser, and

      said joint means (3) comprise:

   first friction pads (5) mounted on a pad support (7) enabling said pads (5) to pivot about respective axes (6) perpendicular to said longitudinal axis of said riser (ZZ'); and

   said first pads (5) co-operating with wheels or second friction pads, preferably with wheels (9), such that said wheels (9) or said second pads bear against said riser, and enable it to slide, and said riser comes to bear against said first pads (5) only when said wheels (9) or said second pads are moved under the effect of lateral displacements of said riser.
2. Apparatus according to claim 1, characterised in that first pads (5) can pivot relative to respective axes (6) secured to said pad support (7).
3. Apparatus according to claim 1, characterised in that said first pads (5) are fixed relative to said pad support (7) and said pad support (7) can pivot relative to said floating support to enable said pads to pivot about an axis (XX') perpendicular to said longitudinal axis (ZZ') of said riser.
4. Apparatus according to claim 3, characterised in that said first pads (5) are fixed on a tubular element (7) encasing said riser coaxially, said tubular element (7) being mounted on a ball and socket joint (8) enabling said pivoting and said rotation respectively of said first pads (5) and of said riser (1).
5. Apparatus according to claim 4, characterised in that said joint (8) is a laminated abutment within which said tubular element (7) is embedded.
6. Apparatus according to any one of claims 1 to 5, characterised in that said second pads or preferably said wheels (9) are mounted on axes (10) extending perpendicularly to the vertical axis (ZZ') of said riser, the axes (10) of said wheels (9) being capable of moving in translation on axes (XX', YY') perpendicular to the longitudinal axis (ZZ') of said riser.
7. Apparatus according to any one of claims 1 to 6, characterised in that said first pads are distributed symmetrically around said riser (1) and comprise at least three pads, preferably being situated at the same level along the longitudinal axis (ZZ') of said riser.
8. Apparatus according to any one of claims 1 to 7, characterised in that said second pads or preferably said wheels (9) are disposed symmetrically around said riser (1) about its longitudinal axis (ZZ') and with at least three wheels whose axes of rotation are preferably situated substantially in the same plane.
9. Apparatus according to any one of claims 1 to 8, characterised in that said first pads (5) are mounted on respective axes (6₂) situated substantially in the same horizontal plane as the axes of said wheels (9), and said pads (5) and said wheels (9) are disposed successively and symmetrically around said riser (1) in alternating manner.
10. Apparatus according to any one of claims 1 to 9, characterised in that said first pads (5) and said wheels (9) are disposed in a staggered configuration, their respective pivot and rotation axes being situated at different respective levels along the longitudinal axis (ZZ') of said riser.
11. Apparatus according to any one of claims 1 to 10, characterised in that said first pads (5) are disposed on at least two different levels (P₁ and P₂) along said longitudinal axis (ZZ') of said riser, and said levels (P₁ and P₂) are disposed symmetrically about a horizontal plane corresponding substantially to the midplane (P₀) of the zone along the longitudinal axis (ZZ') where said joint means (3) are situated.
12. Apparatus according to any one of claims 1 to 11, characterised in that the axes of rotation of the wheels (9) are disposed on at least two different planes (P₃, P₄) perpendicular to said longitudinal axis (ZZ') of said riser, and said planes (P₃, P₄) are disposed symmetrically about a horizontal plane (P₀) corresponding substantially to said midplane of the zone along the longitudinal axis of said riser where said joint means (3) are situated.
13. Apparatus according to any one of claims 1 to 12, characterised in that said first pads are situated on two different levels along the longitudinal axis (ZZ') of said riser, an upper level (P₁) and a lower level (P₂), and said second pads or preferably said wheels are situated above said upper level (P₁) and below said lower level (P₂).
14. Apparatus according to any one of claims 1 to 13, characterised in that said first pads (5) are situated on two of said different levels, an upper level (P₁) and a lower level (P₂), and said wheels (9) are situated between said levels (P₁ ) and (P₂).
15. Apparatus according to any one of claims 1 to 14, characterised in that it is installed on the floating support to hold and guide one of said risers in its production position (11).
16. Apparatus according to any one of claims 1 to 14, characterised in that it is connected to transfer means (12) for transferring one of said risers from its production position to the axis of a drilling derrick (13).
17. Apparatus according to any one of claims 1 to 14, characterised in that it is installed on said floating support to hold and guide one of said risers in an operating position (14) in a derrick (13) installed on said floating support.
18. Apparatus according to any one of claims 15 to 17, characterised in that said joint means (3) are mounted on the junction floor (4) between said riser and said floating support, situated at the level (P₀) of the wall (20) of the cavity (23) of said floating support between the level of the deck (21) of the floating support and the water level (33).
19. Apparatus according to claim 17 or 18, characterised in that it comprises:

    said joint means (3) comprising pads (5) preferably co-operating with wheels (9) situated on a first level (P'₁) and a second level (P'₂) along the wall (20) of the cavity (23) of the floating support, preferably respectively above and below the level (P₀ ) of said junction floor (4) between the riser and said floating support; and

    the upper and lower levels (P₁ ) and (P₂) are far enough apart to hold said riser substantially on the axis of said derrick, and to allow essentially vertical movements along said vertical axis (ZZ') of said riser and the derrick, the angular displacements of said riser relative to the axis of said derrick being less than 5°, and preferably less than 2°.
20. Apparatus according to claim 19, characterised in that said joint means (3) are fixed inside a collar (15) held in place around the riser by cables (16) connected by a tensioning system (17) to the wall (20) of the cavity (23) of said floating support, at at least one of said levels (P₁ ) and (P₂).
21. Apparatus according to claim 20, characterised in that the collar (15) is positioned around the riser (1) by adjusting the lengths of two of said cables (16), the other cables being kept under tension.
22. Apparatus according to claim 19, characterised in that it comprises, at each of said levels (P₁ ) and (P₂) a system of articulated arms (18) including hydraulic actuators (19) with said joint means (3) being mounted at the ends of said arms; each of said articulated arms preferably being capable of being adjusted in length so as to create an offset between the axis of the riser and the axis of the derrick.
23. Apparatus according to claim 22, characterised in that the articulated arm system (18) can move between a closed position and an open position, such that:

    in the closed position, said joint means (3), preferably said wheels (9) are in contact with said riser; and

    in the open position, it allows a float (32) fitted to said floating riser to pass through, said joint means and preferably said wheels remaining in contact with said float.
24. A method of holding and guiding a floating riser (1) relative to a floating support (2) enabling said riser to slide along its longitudinal axis (ZZ') and guiding lateral displacements thereof in a horizontal plane (XX', YY') perpendicular to said riser, by means of apparatus according to one of claims 1 to 23.
25. A method of transferring a riser on a floating support from its production position (11) to its position (12) within a drilling derrick, the method being characterised in that said riser (1) is displaced in a cavity (24) of the floating support by displacing said apparatus (9) for holding and guiding the riser relative to the floating support and according to claim 16, the apparatus itself being secured to said riser (1).
26. A transfer method according to claim 25, characterised in that the floating support is of the type having a central cavity (23) within which a plurality of risers (1) can be positioned, and said central cavity (23) has a plurality of compartments (23₁) at the ends of which said risers (1) are in their production positions (11), said compartments communicating with a central channel (24), at the end of which there is situated (13) a drilling derrick (14), said compartments being disposed transversely relative to said central channel (24).
27. A method according to claim 26, characterised in that said compartments (23) and said central channel (24) comprise a junction floor (4) between said riser and said floating support on each of the rims defining a continuous channel of substantially constant width, and the floating support has transfer means (12) for transferring said risers (1) between their production positions (11) at the ends of the compartments (23₁), and the position (13) of the derrick (14), said transfer means enabling one of said risers to be moved along said junction floor (4) in cooperation with one of said riser holding and guidance apparatuses (3), said apparatus providing the junction between said riser (1) and said floating support.
28. A transfer method according to claim 27, characterised in that said transfer means (12) are fixed and secured to said floating support.
29. A transfer method according to claim 28, characterised in that said transfer means (12) comprise a set of winches (12₁) and of cables (12₂) connecting said winches (12₁) to said riser (1).
30. A transfer method according to claim 27, characterised in that said transfer means (12) comprise a carriage that is movable along said compartments (23₁) and along said central channel (24).
31. A transfer method according to any one of claims 27 to 30, characterised in that said junction floor (4) is fitted with guide rails (12₃) enabling said transfer means or said riser to be moved along said compartments (23₁) and along said central channel (24).

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