EP1250510A1 - Seafloor-surface linking device comprising a stabilising element - Google Patents

Seafloor-surface linking device comprising a stabilising element

Info

Publication number
EP1250510A1
EP1250510A1 EP01907665A EP01907665A EP1250510A1 EP 1250510 A1 EP1250510 A1 EP 1250510A1 EP 01907665 A EP01907665 A EP 01907665A EP 01907665 A EP01907665 A EP 01907665A EP 1250510 A1 EP1250510 A1 EP 1250510A1
Authority
EP
European Patent Office
Prior art keywords
pipe
float
floats
riser
stabilizing
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP01907665A
Other languages
German (de)
French (fr)
Other versions
EP1250510B1 (en
Inventor
Olivier Lenormand
Michel Gassert
Stéphane COUPRIE
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Saipem SA
Original Assignee
Bouygues Offshore SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bouygues Offshore SA filed Critical Bouygues Offshore SA
Publication of EP1250510A1 publication Critical patent/EP1250510A1/en
Application granted granted Critical
Publication of EP1250510B1 publication Critical patent/EP1250510B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
    • E21B17/01—Risers
    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
    • E21B17/01—Risers
    • E21B17/012—Risers with buoyancy elements

Definitions

  • the present invention relates to the known field of bottom-surface connections of the type comprising a vertical submarine pipe, called riser, connecting the bottom of the sea to a floating support installed on the surface.
  • This floating support generally comprises anchoring means to remain in position despite the effects of currents, winds and swell. In general, it also includes means for storing and processing petroleum as well as means for unloading towards tanker removers.
  • the name of these floating supports is the English term “Floating Production Storage Offloading” (meaning “floating means of storage, production and unloading”) abbreviated by "FPSO”.
  • FPSO Floating Production Storage Offloading
  • the well heads are often distributed over the entire field and the production pipes, as well as the water injection lines and the control cables, are laid on the sea floor in the direction of a fixed location , vertically from which the floating support is positioned on the surface.
  • Some wells are located vertical to the floating support and the interior of the well is then accessible directly from the surface.
  • the well head fitted with its "Christmas tree” can be installed on the surface, on board the floating support. It is then possible to carry out, from a derrick installed on said floating support, all the drilling, production and maintenance operations of the well throughout the lifetime of said well. This is known as a dry wellhead.
  • Patent No. 2 754 01 1 is known in the name of IFP describing a barge and a guidance system for riser, the latter being fitted with floats.
  • the underwater pipe then consists of a riser comprising an underwater pipe assembled with at least one float comprising a coaxial container surrounding said pipe and crossed by said pipe.
  • means for joining said container and said pipe comprise a sealed joint assembled around said pipe at at least one of the upper or lower orifices of said container.
  • the floats concerned are large with in particular a diameter greater than 5m, and a length of 10 to 20m and have buoyancies of up to 100 tonnes.
  • the floats are generally arranged in a chain one below the other.
  • the floats generally extend over a length corresponding approximately to no more than 10% of the length of the bottom-surface connection; especially over a length of 100 to 200 meters.
  • the riser is tensioned by these floats and is guided, preferably at the floating support, by roller guides located in a plane allowing the maintenance and guidance of a riser relative to the floating support. Cable tensioning means acting as a guide can be used.
  • FR 2 754 021 discloses a device for guiding a riser provided with floats at the head comprising rollers allowing the vertical sliding of the riser, as well as its rotation about a horizontal axis and guiding its horizontal movements, so that the horizontal translational movements of the riser substantially follow those of the floating support.
  • FR 99 1041 7 is an improved guide device comprising rollers and friction pads arranged radially around the pipe.
  • various guidance systems are known which involve cable tensioning.
  • the entire riser then behaves like a rope stretched between the bottom of the sea and the point located at the axis of the guidance system at the floating support.
  • This riser is subject to the effects of swell, current and moreover to the horizontal movements of said floating support also subjected to the same effects.
  • the water in motion in the slice of water creates drag effects on the structure of the riser and its floats, thereby generating significant efforts of variable direction.
  • riser stabilization devices which are subjected to “guitar” type vibrations linked to the effects of vortex or vortex disturbance around the riser.
  • the floats are distributed over the entire length of the riser in the form of a cylindrical shell of syntactic foam.
  • the stabilization device consists in modifying the shape of the floats in the upper part corresponding to the slice of water subjected to the swell, to obtain a non-cylindrical surface of hexagonal section.
  • the solution proposed in WO 99/05389 results in a reduction in the volume of the floats in the upper part and therefore a reduction in their buoyancy compared to the rest of the riser, with equivalent bulk.
  • This type of modification with plane geometry has the effect of an increase in the drag and a reduction in the excitation induced by the vortex detachments, and stabilizes the riser only by absorption of energy.
  • a tubular pipe is stabilized also subjected only to a vibration according to the "guitar" mode by equipping it with a plurality of envelopes perforated at different levels around the current part of the pipe. These perforated envelopes are sliding around the pipe to be placed specifically at the location of the areas subjected to vibrations corresponding to the belly of the vibration.
  • the present invention relates to the stabilization of a type of bottom-surface bond different from those described in the prior art and proposes an original stabilization solution.
  • the present invention relates to a bottom-surface connection device comprising at least one underwater pipe comprising at least one float, preferably a plurality of floats in a chain, said floats consisting of cans surrounding said pipe, located in the upper submerged part of the pipe, said pipe being held on the surface by a guide device, preferably at a floating support, and the part located below the area of the floats therefore being predominantly, or even completely, devoid of float.
  • the term “guiding device” means the devices known to those skilled in the art allowing the vertical sliding of the riser, as well as its rotation about a horizontal axis and guiding its horizontal displacements, so that these are checked and preferably substantially follow those of the floating support if necessary.
  • the problem of the invention is to prevent or reduce the appearance of vibrations corresponding to the combined modes of the "pendulum-guitar" type on the risers stretched by floats located at the head, when they are excited by the swell and the current or the horizontal displacements of the barge, reducing or, preferably, eliminating the pendulum behavior of the upper part of the riser.
  • the inventors have demonstrated that the problem posed is to avoid or reduce the hydrodynamic phenomena at the origin of the excitation of the vibratory modes of the coupled "riser-float” system, and to avoid or reduce the response of the coupled "riser-floats" system to excitations.
  • the invention thus relates to the installation of devices providing a solution to one or the other, or to both aspects of the problem.
  • the problem of the present invention therefore relates according to a first aspect, the elimination or reduction of the excitation of the vibratory modes of the coupled system "riser-floats".
  • the inventors have demonstrated that according to this first aspect, the problem only concerns the implementation of devices influencing the hydrodynamic excitation of the vibrational modes due to the vortex detachments appearing on the contour of the floats or of the riser.
  • the problem of the present invention also relates, according to a second aspect, to the elimination or reduction of the response of the coupled "riser-float" system to the excitations due to hydrodynamic phenomena or to the horizontal movements of the barge.
  • the problem relates to the implementation of devices aiming to modify the frequencies of the vibration modes of the coupled “riser-float” system in order to move away from the frequencies of vortex detachments and avoid the "hooking phenomenon".
  • the present invention provides a bottom-surface connection device comprising at least one underwater pipe comprising at least one float, preferably a plurality of floats in a chain, said floats consisting of cans surrounding said pipe, located in the submerged upper part of the pipe, said pipe being held on the surface by a guide device, preferably at a floating support.
  • the part located below the float area is therefore mainly or even completely devoid of float.
  • said device comprises at least one stabilizing device located in the upper part of the pipe consisting of:
  • Said “riser-float” transition zone corresponds to a zone where the mechanical characteristics of the pipe (the diameter, the section or the inertia of the pipe) gradually decrease downwards until reaching the current part of the pipe, which corresponds to the part of the substantially constant diameter pipe located below said transition zone.
  • the invention takes advantage of the very particular pendulum behavior of this type of bottom-surface connection, to contribute to the stabilization of the system.
  • the stabilization devices according to the invention are advantageously located at the lower end of the area of the floats or below the chain of floats, since the inventors have demonstrated that this location corresponds to the area where the excitation of the vortex detachments is predominant. Indeed, this excitement is strongly related to the amplitude of the horizontal displacement of the riser; and at this location the lever arm is the largest relative to the axis of rotation of the pendulum type movement. This location therefore increases the stabilizing effect of the stabilization device.
  • said location constitutes a singular point of said pipe because the tension there is maximum.
  • said stabilizing devices of the invention thus make it possible to reduce, or even eliminate, jointly the excitation and the response of the vibratory modes of the coupled "riser-float" system. More particularly, said stabilizing device comprises at least one device chosen from: an energy absorption device,
  • the stabilizing device combines at least two, preferably all three, of the effects chosen from:
  • the energy absorption is obtained by a structural element increasing the contact surface with water and / or creating a non-cylindrical contact surface with water relative to the axis of said pipe.
  • this structural element can be constituted by:
  • an additional structural element associated with the surface of the float or of the pipe can have a surface with three-dimensional or planar geometry.
  • this surface with three-dimensional geometry is a surface not parallel to the cylindrical surface of the pipe.
  • said stabilizing device comprises, one of the following embodiments, taken separately or in combination:
  • a stabilizing device comprising an additional mass located in or around a float or surrounding said pipe.
  • said stabilizing device comprises a box, preferably coaxial surrounding said pipe, the external surface of which comprises perforations. "Perforation” means any space or any opening allowing water to pass inside.
  • the stabilizing device when it is a perforated box, it combines various aspects, namely that it consists of a device lowering the center of gravity since it is located in the lower part of the zone of floats, and a device increasing the mass of water entrained during its movement to the extent that it contains water, and an energy absorbing device by increasing the drag related to the perforations of the surface.
  • a non-perforated float partially or completely filled with water.
  • the invention therefore consists in using in particular either additional devices, such as propellers or perforated boxes, or non-cylindrical floats of various shapes, or even the combination of these two types of solutions.
  • the float area includes several floats, preferably at least four.
  • the stabilizing device is located on or at the level of the lowest float, or in said transition zone, just below the lowest float.
  • Said structural elements with three-dimensional geometry absorb energy, so as to limit the appearance of vortex detachments and / or reduce their correlation lengths, while increasing the mass of entrained water.
  • the stabilizing devices by energy absorption and increase in the mass of entrained water also contribute to modifying advantageously, preferably to reducing, the natural frequencies of vibration of the system.
  • the invention also includes the implementation of a stabilizing device making it possible to increase the inertia of the string of floats by lowering its center of gravity, and on the other hand, into a device making it possible to increase the mass of water entrained during its movement, mass of water known to those skilled in the art under the designation of "added mass”.
  • a stabilizing device making it possible to increase the inertia of the string of floats by lowering its center of gravity
  • a device making it possible to increase the mass of water entrained during its movement, mass of water known to those skilled in the art under the designation of "added mass”.
  • These devices are also preferably installed on the lower part of the string of floats or below where they are particularly effective because the dynamics of the coupled system is mainly governed by the pendular movement of the floats, and therefore has a significant influence on the natural frequency d oscillation of the moving riser, taken as a whole.
  • the excitation of the vibratory modes is no longer only due to the vortex detachments on the riser considered but also to the interactions of the flow with the other risers of the beam.
  • the implementation of the stabilizing devices envisaged in the context of this invention therefore makes it possible to disorganize the wakes around each riser and advantageously contributes to reducing the excitation of the vibratory modes on the neighboring risers.
  • the present invention also has for its object and a bottom-surface connection device comprising a plurality of underwater pipes according to the invention, that is to say comprising at least one stabilizing device and grouped into bundles.
  • Figure 1 is a side view of a riser fitted with floats associated with a cut side view of an anchored barge supporting processing equipment
  • FIGS. 2, 3 and 4 are side views of a riser tensioned at the head by external means, not shown, in a situation of rest respectively (FIG. 2), and of type vibration
  • FIGS. 5, 6 and 7 are side views of a riser tensioned by floats, in a situation of rest respectively (FIG. 5), and of vibration of the "pendulum-guitar” type respectively in mode 1
  • FIGS. 8 and 9 are side views of a riser comprising floats, the assembly being in an inclined position, which makes it possible to detail the forces F of buoyancy and P of mass linked to the center of gravity, respectively without mass additional and with additional mass,
  • Figure 10 is a side view of a riser having floats, energy absorbers of the "propeller" type being installed on the lowest float
  • Figure 1 1 is a side view of a riser comprising floats, equipped with an energy absorbing device of the turbulence perforated box type, located below and in extension of the lowest float
  • Figure 12 is a side view of a riser equipped with floats of various external shapes whose purpose is to prevent the formation of swirling notches.
  • Figure 13 is a sectional top view of a pipe subjected to a current causing vortices.
  • FIG. 1 is a side view of a bottom-surface connection device comprising a riser 1 equipped with four floats 2.
  • the riser opens into a drilling bay of the barge 15 supporting processing equipment 17.
  • the four floats constitute said zone 4 of the floats.
  • the upper float is of greater diameter and buoyancy, in particular because it is entirely located in the wellbore, that is to say an area of the hull of the floating support, sheltered from the effects of swell and current.
  • connection device comprises in its lower part a pipe 1 of substantially constant diameter, as well as a transition zone 5 having a slight conicity located just below the zone of the floats.
  • the top of the riser is guided by a guide system comprising a roller device 16 integral with the structure of said barge.
  • These guide means allow said riser to slide along its longitudinal axis and guide its lateral movements in a horizontal plane perpendicular to said longitudinal axis of the riser.
  • the guide system is shown schematically, the structure making it integral with the barge is not shown.
  • FIG 13 is a sectional view from above of a pipe 1 subjected to a current 25 causing vortices 26 downstream of said pipe.
  • the vortex phenomenon is represented in position A.
  • the vortex begins in this position, develops then detaches from the structure and is then entrained in the current, downstream of the pipe.
  • a vortex develops in position A
  • another vortex begins in position B, which will evolve thereafter.
  • This position B is substantially symmetrical with the position A with respect to the axis of the current.
  • the vortices are thus generated alternately in positions A and B. This instability is called "alternating vortex detachment".
  • FIGS. 2, 3 and 4 are side views of a pipe 1 embedded at the bottom and tensioned at the head by external means not shown, and guided by a roller device 16, in the respective rest position (FIG. 2), and vibration type "guitar" respectively in mode 1
  • the bellies 12 and nodes 11 are formed in planes 10 located substantially at L / 2 or L / 4.
  • FIGS. 5, 6 and 7 are side views of a riser 1 tensioned by floats 2 and guided at the head by a roller device 16, in respectively a state of rest (FIG. 5), and of vibration of the "guitar” type - pendulum ", respectively in mode 1 (figure 6) and in mode 2 (figure 7).
  • the tension increases from the guide point.
  • the tension is maximum
  • stabilization devices are presented which aim to reduce or eliminate the pendulum behavior of the upper part of the riser. These stabilization devices are located in the area of the floats 4 or in the transition zone 5 "riser-float" which corresponds to an area where the diameter of the pipe decreases progressively downward, until it reaches the current part of the pipe, which corresponds to the part of the pipe with a substantially constant diameter located below said transition zone.
  • FIGS. 8 and 9 representing the area of the floats, the forces F of buoyancy and P of mass linked to the center of gravity of the assembly, respectively without additional mass (FIG. 8) and with an additional mass 7 installed in the lower part of the lower float (figure 9).
  • the additional mass 7 is obtained by an enclosure surrounding the float containing a heavy compound such as iron ores. It could be a float itself filled with water.
  • FIG. 10 is a side view of a riser 1 comprising floats 2, stabilizers of the "propeller" type 8 comprising helical ramps are installed on the lowest float, preferably in its lower part.
  • the propellers 8 could advantageously be installed on the part constituting the transition zone 5, located just below the last float. The zone of maximum efficiency is in one of these two positions.
  • the propellers are installed very punctually, for example on a height of three or 4 meters.
  • Each helical ramp 8 produces only a partial angular section of the contour of the float.
  • FIG. 11 is a side view of a riser 1 comprising floats 2, equipped with a stabilization device of the turbulent perforated box type 9, located below and in extension of the lowest float, for example in the transition zone, that is to say at a depth of about 50 to 100 m away from the effects of the swell.
  • This box consists of a simple envelope pierced with holes of variable section or not, secured to the riser.
  • the mass of water trapped inside the box which can represent 20 to 50 tonnes will be set in motion during lateral movements of the riser and is opposed by its inertia to said movements.
  • the openings in the box allow limited movements of the trapped water outwards, then inwards, which creates additional damping by absorbing energy and thus considerably increases the stabilizing effect.
  • Figure 12 is a side view of a riser 1 equipped with floats 2 of various external shapes whose purpose is to absorb energy to prevent the formation of vortex detachments leading to latching effects.

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  • Geology (AREA)
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  • Fluid Mechanics (AREA)
  • Environmental & Geological Engineering (AREA)
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Abstract

A bottom-to-surface link with at least one underwater pipe having a portion with a substantially constant diameter and one or more floats in a string, the floats constituting cans surrounding the pipe and being located in a float zone around the top underwater portion of the pipe. The pipe is held at the surface by a guide device, preferably on a floating float support. The link includes at least one stabilizer situated in the top portion of the pipe. The link is arranged so that the bottom portion of the float zone, is preferably on or level with the lowest float and a transition zone is between the floats and the substantially constant diameter portion of the pipe.

Description

DISPOSITIF DE LIAISON FOND-SURFACE COMPORTANT UN DISPOSITIF STABILISATEUR BASE-SURFACE LINK DEVICE HAVING A STABILIZER DEVICE
La présente invention concerne le domaine connu des liaisons fond- surface du type comportant une conduite sous-marine verticale, appelée riser, reliant le fond de la mer jusqu'à un support flottant installé en surface.The present invention relates to the known field of bottom-surface connections of the type comprising a vertical submarine pipe, called riser, connecting the bottom of the sea to a floating support installed on the surface.
Dès que la profondeur d'eau devient importante l'exploitation des champs de production notamment des champs pétroliers s'effectue en général à partir d'un support flottant. Ce support flottant comporte en général des moyens d'ancrage pour rester en position malgré les effets des courants, des vents et de la houle. Il comporte aussi en général des moyens de stockage et de traitement du pétrole ainsi que des moyens de déchargement vers des pétroliers enleveurs. L'appellation de ces supports flottants est le terme anglo-saxon "Floating Production Storage Offloading" (signifiant "moyen flottant de stockage, de production et de déchargement") abrégé par "FPSO". De nombreuses variantes ont été développées tels les SPARS, longs cigares flottants maintenus en position par des ancrages caténaires, ou encore les TLPs, plates-formes à lignes d'ancrage tendues, lesdites lignes étant en général verticales.As soon as the water depth becomes significant, the exploitation of production fields, in particular oil fields, is generally carried out from a floating support. This floating support generally comprises anchoring means to remain in position despite the effects of currents, winds and swell. In general, it also includes means for storing and processing petroleum as well as means for unloading towards tanker removers. The name of these floating supports is the English term "Floating Production Storage Offloading" (meaning "floating means of storage, production and unloading") abbreviated by "FPSO". Many variants have been developed such as SPARS, long floating cigars held in position by catenary anchors, or even TLPs, platforms with taut anchor lines, said lines being generally vertical.
Les têtes de puits sont souvent réparties sur la totalité du champ et les conduites de production, ainsi que les lignes d'injection d'eau et les câbles de contrôle commande, sont déposées sur le fond de la mer en direction d'un emplacement fixe, à la verticale duquel le support flottant est positionné en surface.The well heads are often distributed over the entire field and the production pipes, as well as the water injection lines and the control cables, are laid on the sea floor in the direction of a fixed location , vertically from which the floating support is positioned on the surface.
Certains puits sont situés à la verticale du support flottant et l'intérieur du puits est alors accessible directement depuis la surface. Dans ce cas la tête de puits équipée de son "arbre de Noël" peut être installée en surface, à bord du support flottant. On peut alors effectuer, à partir d'un derrick installé sur ledit support flottant, toutes les opérations de forage, de production et de maintenance du puits pendant toute la durée de vie dudit puits. On parle alors de tête de puits sèche.Some wells are located vertical to the floating support and the interior of the well is then accessible directly from the surface. In this case the well head fitted with its "Christmas tree" can be installed on the surface, on board the floating support. It is then possible to carry out, from a derrick installed on said floating support, all the drilling, production and maintenance operations of the well throughout the lifetime of said well. This is known as a dry wellhead.
Pour maintenir le riser équipé de sa tête de puits sèche en position sensiblement verticale il convient d'exercer une traction vers le haut qui peut être appliquée, soit par un système de tensionnement à câbles à l'aide de treuils ou de vérins hydrauliques installés sur le support flottant, soit à l'aide de flotteurs répartis le long du riser et installés à diverses profondeurs, soit encore par une combinaison des deux. On connaît le brevet N°2 754 01 1 au nom de l'IFP décrivant une barge et un système de guidage pour riser, ce dernier étant équipé de flotteurs.To keep the riser fitted with its dry wellhead in a substantially vertical position, pull upwards which can be applied, either by a cable tensioning system using winches or hydraulic jacks installed on the floating support, or using floats distributed along the riser and installed at various depths, or even by a combination of the two. Patent No. 2 754 01 1 is known in the name of IFP describing a barge and a guidance system for riser, the latter being fitted with floats.
La profondeur d'eau de certains champs pétroliers dépassant 1 500m et pouvant atteindre 3 000m, le poids des risers sur de telles hauteurs nécessite leur maintient en position, des efforts pouvant atteindre et dépasser plusieurs centaines de tonnes. On utilise des éléments de flottabilité de type "bidon" rajoutés à des structures immergées, principalement sur les risers reliant la surface aux ultra grands fonds (1000- 3000m) . La conduite sous-marine consiste alors en une colonne montante comportant une conduite sous-marine assemblée à au moins un flotteur comportant un bidon coaxial entourant ladite conduite et traversé par ladite conduite.Since the water depth of certain oil fields exceeds 1,500m and can reach 3,000m, the weight of risers at such heights requires that they be kept in position, efforts that can reach and exceed several hundred tonnes. We use buoyancy elements of the "can" type added to submerged structures, mainly on risers connecting the surface to ultra deep bottoms (1000- 3000m). The underwater pipe then consists of a riser comprising an underwater pipe assembled with at least one float comprising a coaxial container surrounding said pipe and crossed by said pipe.
De préférence, des moyens de jonction dudit bidon et de ladite conduite comprennent une articulation étanche assemblée autour de ladite conduite à au moins l'un des orifices supérieur ou inférieur dudit bidon.Preferably, means for joining said container and said pipe comprise a sealed joint assembled around said pipe at at least one of the upper or lower orifices of said container.
Les flotteurs concernés sont de grandes dimensions avec notamment un diamètre supérieur à 5m, et une longueur de 10 à 20m et possèdent des flottabilités pouvant atteindre 100 tonnes.The floats concerned are large with in particular a diameter greater than 5m, and a length of 10 to 20m and have buoyancies of up to 100 tonnes.
Ils sont en général disposés en chapelet l'un en dessous de l'autre. Les flotteurs s'étendent en général sur une longueur correspondant environ à pas plus de 10% de la longueur de la liaison fond-surface; notamment sur une longueur de 100 à 200 mètres.They are generally arranged in a chain one below the other. The floats generally extend over a length corresponding approximately to no more than 10% of the length of the bottom-surface connection; especially over a length of 100 to 200 meters.
Le riser est mis en tension par ces flotteurs et se trouve guidé, de préférence au niveau du support flottant, par des guidages à rouleaux situés dans un plan permettant le maintien et le guidage d'un riser par rapport au support flottant. Des moyens de tensionnement à câbles jouant le rôle de guidage peuvent être utilisés.The riser is tensioned by these floats and is guided, preferably at the floating support, by roller guides located in a plane allowing the maintenance and guidance of a riser relative to the floating support. Cable tensioning means acting as a guide can be used.
On connaît dans FR 2 754 021 un dispositif de guidage d'un riser muni de flotteurs en tête comprenant des roulettes permettant le coulissement vertical du riser, ainsi que sa rotation autour d'un axe horizontal et guidant ses déplacements horizontaux, de sorte que les mouvements de translation horizontale du riser suivent substantiellement ceux du support flottant. On connaît aussi dans FR 99 1041 7 un dispositif de guidage perfectionné comprenant des roulettes et des patins de frottement disposés radialement autour de la conduite. On connaît enfin divers systèmes de guidage impliquant des tensionnements par câble.FR 2 754 021 discloses a device for guiding a riser provided with floats at the head comprising rollers allowing the vertical sliding of the riser, as well as its rotation about a horizontal axis and guiding its horizontal movements, so that the horizontal translational movements of the riser substantially follow those of the floating support. Also known in FR 99 1041 7 is an improved guide device comprising rollers and friction pads arranged radially around the pipe. Finally, various guidance systems are known which involve cable tensioning.
L'intégralité du riser se comporte alors comme une corde tendue entre le fond de la mer et le point situé à l'axe du système de guidage au niveau du support flottant.The entire riser then behaves like a rope stretched between the bottom of the sea and the point located at the axis of the guidance system at the floating support.
Ce riser est soumis aux effets de la houle, du courant et de plus aux mouvements horizontaux dudit support flottant soumis lui aussi aux mêmes effets. L'eau en mouvement dans la tranche d'eau crée des effets de traînée sur la structure du riser et de ses flotteurs, engendrant de ce fait des efforts importants de direction variable.This riser is subject to the effects of swell, current and moreover to the horizontal movements of said floating support also subjected to the same effects. The water in motion in the slice of water creates drag effects on the structure of the riser and its floats, thereby generating significant efforts of variable direction.
Dans certaines configurations de mouvements de particules d'eau, il se produit des effets d'interaction entre le fluide et le riser qui se traduisent par des détachements tourbillonnaires alternés sur le contour du riser décrits figure 13. Lorsque la période de ce détachement tourbillonnaire alterné est proche des périodes d'excitation propre du riser, il se produit alors le phénomène dit "d'accrochage" qui conduit à des vibrations du riser.In certain configurations of movements of water particles, there are interaction effects between the fluid and the riser which result in alternating vortex detachments on the outline of the riser described in FIG. 13. When the period of this alternating vortex detachment is close to the riser's own excitation periods, the so-called "hooking" phenomenon occurs, which leads to vibrations of the riser.
L'intensité des vibrations générées par les détachements tourbillonnaires alternés, lors de "l'accrochage" , est d'autant plus grande que la longueur de riser sur laquelle les détachements de tourbillons s'effectuent simultanément est importante. Cette longueur est désignée par l'homme de l'art sous le nom de "longueur de corrélation" .The intensity of the vibrations generated by the alternating vortex detachments, during "attachment", is all the greater the longer the riser length over which the vortex detachments take place is important. This length is designated by a person skilled in the art under the name of "correlation length".
Si on regarde le riser comme étant un fil attaché à ses deux extrémités, son comportement global est sujet à des déplacements transversaux de plusieurs mètres présentant une fréquence naturelle d'excitation et des harmoniques correspondant à un mode dit "mode guitare" , c'est à dire que le riser vibre entre ses deux extrémités comme une corde de guitare. Dans le cas des risers sans flotteurs dont les caractéristiques de section (notamment le diamètre, l'inertie, la raideur), sont sensiblement uniformes ou continus, on observe seulement ce mode de vibration de type "guitare" représenté sur les figures 3 et 4. De même, dans le cas d'un riser à forte flottabilité comme dans WOIf we look at the riser as being a wire attached to its two ends, its overall behavior is subject to transverse displacements of several meters presenting a natural frequency of excitation and harmonics corresponding to a mode known as "guitar mode", it is to say that the riser vibrates between its two ends like a guitar string. In the case of risers without floats, the cross-sectional characteristics of which (notably the diameter, inertia, stiffness) are substantially uniform or continuous, only this type of "guitar" type vibration shown in FIGS. 3 and 4 is observed. Similarly, in the case of a riser with high buoyancy as in WO
99/05389 pour lequel la flottabilité est répartie sur toute la longueur du riser pour obtenir une flottabilité d'environ 95 à 98%, on observe seulement des vibrations selon le mode "guitare".99/05389 for which the buoyancy is distributed over the entire length of the riser to obtain a buoyancy of about 95 to 98%, we only observe vibrations according to the "guitar" mode.
Dans WO 95/27101 et WO 99/05389, on connaît des dispositifs de stabilisation de riser soumis à des vibrations de type "guitare" liées aux effets de perturbation tourbillonnaire ou vortex autour du riser.In WO 95/27101 and WO 99/05389, riser stabilization devices are known which are subjected to “guitar” type vibrations linked to the effects of vortex or vortex disturbance around the riser.
Dans WO 99/05389, les flotteurs sont répartis sur toute la longueur du riser sous forme de coquille cylindrique de mousse syntactique. Le dispositif de stabilisation consiste dans la modification de la forme des flotteurs dans la partie supérieure correspondant à la tranche d'eau soumise à la houle, pour obtenir une surface non cylindrique de section hexagonale. La solution proposée dans WO 99/05389 se traduit par une réduction du volume des flotteurs dans la partie haute et donc une réduction de leur flottabilité par rapport au reste du riser, à encombrement équivalent. Ce type de modification à géométrie plane a pour effet une augmentation de la traînée et une diminution de l'excitation induite par les détachements tourbillonnaires, et stabilise le riser seulement par absorption d'énergie.In WO 99/05389, the floats are distributed over the entire length of the riser in the form of a cylindrical shell of syntactic foam. The stabilization device consists in modifying the shape of the floats in the upper part corresponding to the slice of water subjected to the swell, to obtain a non-cylindrical surface of hexagonal section. The solution proposed in WO 99/05389 results in a reduction in the volume of the floats in the upper part and therefore a reduction in their buoyancy compared to the rest of the riser, with equivalent bulk. This type of modification with plane geometry has the effect of an increase in the drag and a reduction in the excitation induced by the vortex detachments, and stabilizes the riser only by absorption of energy.
Dans WO 95/27101 , on stabilise une conduite tubulaire soumise également uniquement à une vibration selon le mode "guitare" en l'équipant d'une pluralité d'enveloppes perforées à différents niveaux autour de la partie courante de la conduite. Ces enveloppes perforées sont coulissantes autour de la conduite pour être mises en place spécifiquement à l'endroit des zones soumises aux vibrations correspondant au ventre de la vibration.In WO 95/27101, a tubular pipe is stabilized also subjected only to a vibration according to the "guitar" mode by equipping it with a plurality of envelopes perforated at different levels around the current part of the pipe. These perforated envelopes are sliding around the pipe to be placed specifically at the location of the areas subjected to vibrations corresponding to the belly of the vibration.
Dans US 4 768 984, on décrit un dispositif de stabilisation d'un riser muni d'une bouée en tête libre, ladite bouée supportant une installation comprenant une plate forme de travail. Cette installation en surface crée un déséquilibre de par l'élévation du centre de gravité par rapport au centre de poussée ou centre de flottabilité qu'elle entraîne. On cherche donc à rétablir la proximité, de préférence la coïncidence entre le centre de gravité et le centre de flottabilité de la partie supérieure de la conduite en aj outant une structure en treillis ou armature, qui constitue une masse, en dessous du flotteur, compensant le poids de la structure au-dessus du flotteur. La structure en treillis ou en armature de par sa forme particulière évite de créer une trop grande augmentation des perturbations dans la zone concernée.In US 4,768,984, a device is described for stabilizing a riser provided with a free head buoy, said buoy supporting an installation comprising a working platform. This installation on the surface creates an imbalance due to the elevation of the center of gravity in relation to the center of thrust or center of buoyancy that it brings about. We therefore seek to restore proximity, preferably coincidence between the center of gravity and the center of buoyancy of the upper part of the pipe by adding a lattice structure or reinforcement, which constitutes a mass, below the float, compensating for the weight of the structure above the float. The lattice or reinforcement structure due to its particular shape avoids creating too great an increase in disturbances in the area concerned.
La présente invention concerne la stabilisation d'un type de liaison fond-surface différent de ceux décrits dans la technique antérieure et propose une solution de stabilisation originale. En effet, la présente invention concerne un dispositif de liaison fond-surface comportant au moins une conduite sous-marine comprenant au moins un flotteur, de préférence une pluralité de flotteurs en chapelet, lesdits flotteurs consistant en des bidons entourant ladite conduite, localisés dans la partie haute immergée de la conduite, ladite conduite étant maintenue en surface par un dispositif de guidage, de préférence au niveau d'un support flottant, et la partie située dessous la zone des flotteurs étant donc majoritairement, voire complètement, dépourvue de flotteur.The present invention relates to the stabilization of a type of bottom-surface bond different from those described in the prior art and proposes an original stabilization solution. In fact, the present invention relates to a bottom-surface connection device comprising at least one underwater pipe comprising at least one float, preferably a plurality of floats in a chain, said floats consisting of cans surrounding said pipe, located in the upper submerged part of the pipe, said pipe being held on the surface by a guide device, preferably at a floating support, and the part located below the area of the floats therefore being predominantly, or even completely, devoid of float.
On entend ici, comme mentionné précédemment, par "dispositif de guidage" les dispositifs connus de l'homme de l'art permettant le coulissement vertical du riser, ainsi que sa rotation autour d'un axe horizontal et guidant ses déplacements horizontaux, de sorte que ceux-ci sont contrôlés et de préférence suivent substantiellement ceux du support flottant le cas échéant.Here, as mentioned above, the term "guiding device" means the devices known to those skilled in the art allowing the vertical sliding of the riser, as well as its rotation about a horizontal axis and guiding its horizontal displacements, so that these are checked and preferably substantially follow those of the floating support if necessary.
Les inventeurs ont découvert que dans le cas de ce type de riser muni de flotteurs seulement en tête et comportant un système de maintien et de guidage en surface, on peut observer un phénomène de vibration très différent et accentué, dans lequel la portion supérieure, correspondant sensiblement à la longueur des flotteurs, se comporte comme un pendule, alors que la partie basse dessous les flotteurs présente un comportement se rapprochant d'un phénomène de type "guitare" . Le comportement de type "pendule" de la partie supérieure du riser est favorisé par la différence d'inertie structurelle entre les deux sections du riser. Ce mouvement "pendulaire" influence de façon très significative le comportement de l'ensemble du riser et on observe alors un couplage du mode "pendule" et des modes "guitare" comme représenté sur les figures 6 et 7. Le comportement global du riser est alors particulièrement sensible à toute excitation qui tend à engendrer le mouvement pendulaire de la partie haute du riser. Ainsi, le problème de l'invention est d'empêcher ou de réduire l'apparition de vibrations correspondant aux modes combinés de type "guitare-pendule" sur les risers tendus par des flotteurs situés en tête, lorsqu'ils sont excités par la houle et le courant ou encore les déplacements horizontaux de la barge, en réduisant ou, de préférence, en éliminant le comportement pendulaire de la partie haute du riser.The inventors have discovered that in the case of this type of riser provided with floats only at the head and comprising a support and guidance system on the surface, a very different and accentuated vibration phenomenon can be observed, in which the upper portion, corresponding appreciably to the length of the floats, behaves like a pendulum, while the lower part below the floats exhibits behavior approaching a "guitar" type phenomenon. The "pendulum" type behavior of the upper part of the riser is favored by the difference in structural inertia between the two sections of the riser. This "pendulum" movement has a very significant influence on the behavior of the entire riser and we then observe a coupling of the "pendulum" mode and "guitar" modes as shown in FIGS. 6 and 7. The overall behavior of the riser is then particularly sensitive to any excitation which tends to generate the pendulum movement of the upper part of the riser. Thus, the problem of the invention is to prevent or reduce the appearance of vibrations corresponding to the combined modes of the "pendulum-guitar" type on the risers stretched by floats located at the head, when they are excited by the swell and the current or the horizontal displacements of the barge, reducing or, preferably, eliminating the pendulum behavior of the upper part of the riser.
Plus particulièrement, les inventeurs ont mis en évidence que le problème posé est d'éviter ou de réduire les phénomènes hydrodynamiques à l'origine de l'excitation des modes vibratoires du système couplé "riser- flotteurs" , et d'éviter ou réduire la réponse du système couplé "riser- flotteurs" aux excitations.More particularly, the inventors have demonstrated that the problem posed is to avoid or reduce the hydrodynamic phenomena at the origin of the excitation of the vibratory modes of the coupled "riser-float" system, and to avoid or reduce the response of the coupled "riser-floats" system to excitations.
S'agissant typiquement d'un problème de type "couplage fluide- structure", l'interaction entre les deux aspects, à savoir, l'excitation et la réponse du système, est forte. Les phénomènes hydrodynamiques ainsi que les mouvements de la barge agissent sur la structure qui, elle-même, rétroagit sur l'excitation d'origine hydrodynamique. L'invention concerne ainsi la mise en place de dispositifs apportant une solution à l'un ou l'autre, ou aux deux aspects du problème.Being typically a problem of type “fluid-structure coupling”, the interaction between the two aspects, namely, the excitation and the response of the system, is strong. The hydrodynamic phenomena as well as the movements of the barge act on the structure which, itself, feedbacks on the excitation of hydrodynamic origin. The invention thus relates to the installation of devices providing a solution to one or the other, or to both aspects of the problem.
Le problème de la présente invention concerne donc selon un premier aspect, l'élimination ou réduction de l'excitation des modes vibratoires du système couplé "riser-flotteurs". Les inventeurs ont mis en évidence que selon ce premier aspect, le problème concerne uniquement la mise en œuvre de dispositifs influant sur l'excitation d'origine hydrodynamique des modes vibratoires due aux détachements tourbillonnaires apparaissant sur le contour des flotteurs ou du riser. Le problème de la présente invention concerne aussi, selon un deuxième aspect, l'élimination ou réduction de la réponse du système couplé "riser-flotteur" aux excitations dues aux phénomènes hydrodynamiques ou aux mouvements horizontaux de la barge. Les inventeurs ont mis en évidence que selon ce deuxième aspect, le problème concerne la mise en œuvre de dispositifs visant à modifier les fréquences des modes de vibration du système couplé "riser-flotteur" afin de s'éloigner des fréquences de détachements tourbillonnaires et éviter le "phénomène d'accrochage".The problem of the present invention therefore relates according to a first aspect, the elimination or reduction of the excitation of the vibratory modes of the coupled system "riser-floats". The inventors have demonstrated that according to this first aspect, the problem only concerns the implementation of devices influencing the hydrodynamic excitation of the vibrational modes due to the vortex detachments appearing on the contour of the floats or of the riser. The problem of the present invention also relates, according to a second aspect, to the elimination or reduction of the response of the coupled "riser-float" system to the excitations due to hydrodynamic phenomena or to the horizontal movements of the barge. The inventors have highlighted that according to this second aspect, the problem relates to the implementation of devices aiming to modify the frequencies of the vibration modes of the coupled “riser-float” system in order to move away from the frequencies of vortex detachments and avoid the "hooking phenomenon".
Pour ce faire, la présente invention fournit un dispositif de liaison fond-surface comportant au moins une conduite sous-marine comprenant au moins un flotteur, de préférence une pluralité de flotteurs en chapelet, lesdits flotteurs consistant en des bidons entourant ladite conduite, localisés dans la partie haute immergée de la conduite, ladite conduite étant maintenue en surface par un dispositif de guidage, de préférence au niveau d'un support flottant. La partie située dessous la zone des flotteurs est donc maj oritairement, voire complètement, dépourvue de flotteur.To do this, the present invention provides a bottom-surface connection device comprising at least one underwater pipe comprising at least one float, preferably a plurality of floats in a chain, said floats consisting of cans surrounding said pipe, located in the submerged upper part of the pipe, said pipe being held on the surface by a guide device, preferably at a floating support. The part located below the float area is therefore mainly or even completely devoid of float.
Selon la présente invention, ledit dispositif comprend au moins un dispositif stabilisateur situé dans la partie supérieure de la conduite constituée par :According to the present invention, said device comprises at least one stabilizing device located in the upper part of the pipe consisting of:
- la partie basse de la zone des flotteurs, de préférence sur ou au niveau du flotteur le plus bas, et- the lower part of the float area, preferably on or at the lowest float, and
- la zone de transition entre les flotteurs et la partie courante à diamètre sensiblement constant de ladite conduite.- The transition zone between the floats and the main part with a substantially constant diameter of said pipe.
Ladite zone de transition "riser-flotteur" correspond à une zone où les caractéristiques mécaniques de la conduite (le diamètre, la section ou l'inertie de la conduite) décroissent progressivement vers le bas jusqu'à atteindre la partie courante de la conduite, laquelle correspond à la partie de la conduite à diamètre sensiblement constant située en dessous de ladite zone de transition.Said “riser-float” transition zone corresponds to a zone where the mechanical characteristics of the pipe (the diameter, the section or the inertia of the pipe) gradually decrease downwards until reaching the current part of the pipe, which corresponds to the part of the substantially constant diameter pipe located below said transition zone.
L'invention tire profit du comportement pendulaire très particulier de ce type de liaison fond-surface, pour contribuer à la stabilisation du système. En effet, les dispositifs de stabilisation selon l'invention sont avantageusement localisés à l'extrémité inférieure de la zone des flotteurs ou dessous le chapelet de flotteurs, car les inventeurs ont mis en évidence que cette localisation correspond à la zone où l'excitation des détachements tourbillonnaires est prédominante. En effet, cette excitation est fortement liée à l'amplitude du déplacement horizontal du riser ; et à cette localisation le bras de levier est le plus important par rapport à l'axe de rotation du mouvement de type pendule. Cette localisation augmente donc l'effet stabilisateur du dispositif de stabilisation. De plus, ladite localisation constitue un point singulier de ladite conduite car la tension y est maximale.The invention takes advantage of the very particular pendulum behavior of this type of bottom-surface connection, to contribute to the stabilization of the system. In fact, the stabilization devices according to the invention are advantageously located at the lower end of the area of the floats or below the chain of floats, since the inventors have demonstrated that this location corresponds to the area where the excitation of the vortex detachments is predominant. Indeed, this excitement is strongly related to the amplitude of the horizontal displacement of the riser; and at this location the lever arm is the largest relative to the axis of rotation of the pendulum type movement. This location therefore increases the stabilizing effect of the stabilization device. In addition, said location constitutes a singular point of said pipe because the tension there is maximum.
Les dispositifs stabilisateurs de l'invention permettent ainsi de réduire, voire d'éliminer, conjointement l'excitation et la réponse des modes vibratoires du système couplé "riser-flotteur". Plus particulièrement, ledit dispositif stabilisateur comprend au moins un dispositif choisi parmi : un dispositif d'absorption d'énergie,The stabilizing devices of the invention thus make it possible to reduce, or even eliminate, jointly the excitation and the response of the vibratory modes of the coupled "riser-float" system. More particularly, said stabilizing device comprises at least one device chosen from: an energy absorption device,
- un dispositif augmentant la masse d'eau entraînée au cours de son mouvement, et - un dispositif abaissant le centre de gravité de ladite partie supérieure de la conduite. De préférence, le dispositif stabilisateur cumule au moins deux, de préférence les trois, des effets choisis parmi :- a device increasing the mass of water entrained during its movement, and - a device lowering the center of gravity of said upper part of the pipe. Preferably, the stabilizing device combines at least two, preferably all three, of the effects chosen from:
- l'absorption d'énergie, - l'augmentation de la masse d'eau entraînée au cours de son mouvement, et- energy absorption, - increase in the mass of water entrained during its movement, and
- l'abaissement du centre de gravité de ladite partie supérieure de la conduite.- Lowering the center of gravity of said upper part of the pipe.
Dans un mode de réalisation l'absorption d'énergie est obtenue par un élément de structure augmentant la surface de contact avec l'eau et/ou créant une surface de contact avec l'eau non cylindrique par rapport à l'axe de ladite conduite.In one embodiment, the energy absorption is obtained by a structural element increasing the contact surface with water and / or creating a non-cylindrical contact surface with water relative to the axis of said pipe. .
Ainsi, cet élément de structure peut être constitué par :Thus, this structural element can be constituted by:
- une modification de la forme de la surface du flotteur ou de la conduite, celle-ci présentant alors une forme non cylindrique, par rapport à l'axe de ladite conduite, oua modification of the shape of the surface of the float or of the pipe, the latter then having a non-cylindrical shape, relative to the axis of said pipe, or
- un élément de structure additionnel associé à la surface du flotteur ou de la conduite. Ledit élément de structure additionnel augmentant la surface de contact du flotteur ou de la conduite avec l'eau peut présenter une surface à géométrie tridimensionnelle ou plane. De préférence, cette surface à géométrie tridimensionnelle est une surface non parallèle à la surface cylindrique de la conduite.- an additional structural element associated with the surface of the float or of the pipe. Said additional structural element increasing the contact surface of the float or of the pipe with water can have a surface with three-dimensional or planar geometry. Preferably, this surface with three-dimensional geometry is a surface not parallel to the cylindrical surface of the pipe.
Avantageusement, ledit dispositif stabilisateur comprend, l'un des modes de réalisation suivant, pris séparément ou en combinaison :Advantageously, said stabilizing device comprises, one of the following embodiments, taken separately or in combination:
- la forme non cylindrique de la surface extérieure d'un flotteur ou d'une partie de conduite, et - une rampe hélicoïdale entourant un dit flotteur ou ladite conduite.- the non-cylindrical shape of the outer surface of a float or of a pipe part, and - a helical ramp surrounding a said float or said pipe.
Comme dit dispositif abaissant le centre de gravité de la partie supérieure de la conduite on peut citer un dispositif stabilisateur comprenant une masse additionnelle située dans ou autour d'un flotteur ou entourant ladite conduite. Dans un mode de réalisation ledit dispositif stabilisateur comprend un caisson, de préférence coaxial entourant ladite conduite dont la surface extérieure comprend des perforations. Par "perforation" , on entend tout espace ou toute ouverture laissant passer l'eau à l'intérieur.As said device lowering the center of gravity of the upper part of the pipe, mention may be made of a stabilizing device comprising an additional mass located in or around a float or surrounding said pipe. In one embodiment, said stabilizing device comprises a box, preferably coaxial surrounding said pipe, the external surface of which comprises perforations. "Perforation" means any space or any opening allowing water to pass inside.
Dans certains modes de réalisation, notamment lorsque le dispositif stabilisateur est un caisson perforé, celui-ci cumule différents aspects, à savoir qu'il consiste en un dispositif abaissant le centre de gravité puisqu'il est situé dans la partie inférieure de la zone des flotteurs, et un dispositif augmentant la masse d'eau entraînée au cours de son mouvement dans la mesure où il contient de l'eau, et un dispositif absorbeur d'énergie de par l'augmentation de la traînée liée aux perforations de la surface.In certain embodiments, in particular when the stabilizing device is a perforated box, it combines various aspects, namely that it consists of a device lowering the center of gravity since it is located in the lower part of the zone of floats, and a device increasing the mass of water entrained during its movement to the extent that it contains water, and an energy absorbing device by increasing the drag related to the perforations of the surface.
Comme dispositif apportant une masse additionnelle on peut citer un flotteur non perforé partiellement ou totalement rempli d'eau.As a device providing additional mass, there may be mentioned a non-perforated float partially or completely filled with water.
L'invention consiste donc à utiliser en particulier soit des dispositifs additionnels, tels des hélices ou des caissons perforés, soit des flotteurs non cylindriques de formes variées, soit encore la combinaison de ces deux types solutions.The invention therefore consists in using in particular either additional devices, such as propellers or perforated boxes, or non-cylindrical floats of various shapes, or even the combination of these two types of solutions.
Dans un mode de réalisation, la zone des flotteurs comprend plusieurs flotteurs, de préférence au moins quatre. De préférence, le dispositif stabilisateur est situé sur ou au niveau du flotteur le plus bas, ou dans ladite zone de transition, juste en dessous du flotteur le plus bas.In one embodiment, the float area includes several floats, preferably at least four. Preferably, the stabilizing device is located on or at the level of the lowest float, or in said transition zone, just below the lowest float.
Lesdits éléments de structure à géométrie tridimensionnelle absorbent de l'énergie, de manière à limiter l'apparition des détachements tourbillonnaires et/ou réduire leurs longueurs de corrélation, tout en augmentant la masse d'eau entraînée.Said structural elements with three-dimensional geometry absorb energy, so as to limit the appearance of vortex detachments and / or reduce their correlation lengths, while increasing the mass of entrained water.
Les dispositifs stabilisateurs par absorption d'énergie et augmentation de la masse d'eau entraînée contribuent aussi à modifier avantageusement, de préférence à réduire, les fréquences propres de vibration du systèmeThe stabilizing devices by energy absorption and increase in the mass of entrained water also contribute to modifying advantageously, preferably to reducing, the natural frequencies of vibration of the system.
"riser-flotteur" et donc à réduire sa réponse à l'excitation due aux phénomènes hydrodynamique ou aux mouvements horizontaux de la barge."riser-float" and therefore reduce its response to excitation due to hydrodynamic phenomena or to the horizontal movements of the barge.
L'invention comprend également la mise en œuvre d'un dispositif stabilisateur permettant d'augmenter l'inertie du chapelet de flotteurs en abaissant son centre de gravité, et d'autre part, en un dispositif permettant d'augmenter la masse d'eau entraînée au cours de son mouvement, masse d'eau connue par l'homme de l'art sous la désignation de "masse ajoutée" . Ces deux types de stabilisateurs peuvent être concomitants dans un même dispositif comme mentionné ci-dessus. Ces dispositifs d'abaissement du centre de gravité et d'augmentation de la "masse ajoutée", en dehors de leur effet favorable sur les fréquences de vibration du système couplé "riser-flotteur", permettent de stabiliser la partie haute du riser en augmentant son inertie et contribue ainsi à l'amortissement du mouvement pendulaire. Ces dispositifs sont également installés de préférence sur la partie inférieure du chapelet de flotteurs ou en dessous où ils sont particulièrement efficaces car la dynamique du système couplé est principalement gouvernée par le mouvement pendulaire des flotteurs, et influe donc de manière importante sur la fréquence propre d'oscillation du riser en mouvement, pris dans sa globalité. Dans le cas de risers regroupés en faisceau, l'excitation des modes vibratoires n'est plus seulement due aux détachements tourbillonnaires sur le riser considéré mais également aux interactions de l'écoulement avec les autres risers du faisceau. La mise en place des dispositifs stabilisateurs envisagés dans le cadre de cette invention permet donc de désorganiser les sillages autour de chaque riser et contribue avantageusement à réduire l'excitation des modes vibratoires sur les risers voisins.The invention also includes the implementation of a stabilizing device making it possible to increase the inertia of the string of floats by lowering its center of gravity, and on the other hand, into a device making it possible to increase the mass of water entrained during its movement, mass of water known to those skilled in the art under the designation of "added mass". These two types of stabilizers can be concomitant in the same device as mentioned above. These devices for lowering the center of gravity and increasing the "added mass", apart from their favorable effect on the vibration frequencies of the coupled "riser-float" system, make it possible to stabilize the upper part of the riser by increasing its inertia and thus contributes to the damping of the pendulum movement. These devices are also preferably installed on the lower part of the string of floats or below where they are particularly effective because the dynamics of the coupled system is mainly governed by the pendular movement of the floats, and therefore has a significant influence on the natural frequency d oscillation of the moving riser, taken as a whole. In the case of risers grouped in a beam, the excitation of the vibratory modes is no longer only due to the vortex detachments on the riser considered but also to the interactions of the flow with the other risers of the beam. The implementation of the stabilizing devices envisaged in the context of this invention therefore makes it possible to disorganize the wakes around each riser and advantageously contributes to reducing the excitation of the vibratory modes on the neighboring risers.
La présente invention a également pour obj et un dispositif de liaison fond-surface comportant une pluralité de conduites sous-marines selon l'invention, c'est-à-dire comprenant au moins un dispositif stabilisateur et regroupés en faisceaux.The present invention also has for its object and a bottom-surface connection device comprising a plurality of underwater pipes according to the invention, that is to say comprising at least one stabilizing device and grouped into bundles.
D'autres caractéristiques et avantages de la présente invention apparaîtront à la lumière de la description détaillée qui va suivre, en référence aux figures suivantes dans lesquelles : • la figure 1 est une vue de côté d'un riser équipé de flotteurs associés à une coupe en vue de côté d'une barge ancrée supportant des équipements de traitement,Other characteristics and advantages of the present invention will appear in the light of the detailed description which follows, with reference to the following figures in which: • Figure 1 is a side view of a riser fitted with floats associated with a cut side view of an anchored barge supporting processing equipment,
• les figures 2, 3 et 4 sont des vues de côté d'un riser tensionné en tête par des moyens extérieurs non représentés, en situation respectivement de repos (figure 2) , et de vibration de typeFIGS. 2, 3 and 4 are side views of a riser tensioned at the head by external means, not shown, in a situation of rest respectively (FIG. 2), and of type vibration
"guitare" respectivement en mode 1 (figure 3) et en mode 2 (figure 4) ,"guitar" respectively in mode 1 (figure 3) and in mode 2 (figure 4),
• les figures 5, 6 et 7 sont des vues de côté d'un riser tensionné par des flotteurs, en situation respectivement de repos (figure 5) , et de vibration de type "guitare-pendule" respectivement en mode 1FIGS. 5, 6 and 7 are side views of a riser tensioned by floats, in a situation of rest respectively (FIG. 5), and of vibration of the "pendulum-guitar" type respectively in mode 1
(figure 6) et en mode 2 (figure 8) ,(figure 6) and in mode 2 (figure 8),
• les figures 8 et 9 sont des vues de côté d'un riser comportant des flotteurs, l'ensemble étant en position inclinée, ce qui permet de détailler les forces F de flottabilité et P de masse liée au centre de gravité, respectivement sans masse additionnelle et avec masse additionnelle,FIGS. 8 and 9 are side views of a riser comprising floats, the assembly being in an inclined position, which makes it possible to detail the forces F of buoyancy and P of mass linked to the center of gravity, respectively without mass additional and with additional mass,
• la figure 10 est une vue de côté d'un riser comportant des flotteurs, des absorbeurs d'énergie de type "hélice" étant installés sur le flotteur le plus bas, • la figure 1 1 est une vue de côté d'un riser comportant des flotteurs, équipé d'un dispositif absorbeur d'énergie de type caisson perforé à turbulences, situé en dessous et en prolongement du flotteur le plus bas, • la figure 12 est une vue de côté d'un riser équipé de flotteurs de formes extérieures variées dont le but est d'empêcher la formation de décrochements tourbillonnaires.• Figure 10 is a side view of a riser having floats, energy absorbers of the "propeller" type being installed on the lowest float, • Figure 1 1 is a side view of a riser comprising floats, equipped with an energy absorbing device of the turbulence perforated box type, located below and in extension of the lowest float, • Figure 12 is a side view of a riser equipped with floats of various external shapes whose purpose is to prevent the formation of swirling notches.
• la figure 13 est une coupe en vue de dessus d'une conduite soumise à un courant provoquant des tourbillons.• Figure 13 is a sectional top view of a pipe subjected to a current causing vortices.
La figure 1 est une vue de côté d'un dispositif de liaison fond-surface comprenant un riser 1 équipé de quatre flotteurs 2. Le riser débouche dans une baie de forage de la barge 15 supportant des équipements de traitement 17. Les quatre flotteurs constituent ladite zone 4 des flotteurs. Le flotteur supérieur est de diamètre et de flottabilité plus importante notamment car il est intégralement situé dans la baie de forage, c'est-à-dire une zone de la coque du support flottant, abritée des effets de la houle et du courant.FIG. 1 is a side view of a bottom-surface connection device comprising a riser 1 equipped with four floats 2. The riser opens into a drilling bay of the barge 15 supporting processing equipment 17. The four floats constitute said zone 4 of the floats. The upper float is of greater diameter and buoyancy, in particular because it is entirely located in the wellbore, that is to say an area of the hull of the floating support, sheltered from the effects of swell and current.
Le dispositif de liaison comporte dans sa partie basse une conduite 1 de diamètre sensiblement constant , ainsi qu'une zone de transition 5 présentant une légère conicité située juste dessous la zone des flotteurs. Le sommet du riser est guidé par système de guidage comprenant un dispositif à rouleaux 16 solidaire de la structure de ladite barge. Ces moyens de guidage permettent le coulissement dudit riser selon son axe longitudinal et guident ses déplacements latéraux dans un plan horizontal perpendiculaire audit axe longitudinal du riser. Sur les figures 1 à 12 le système de guidage est représenté schématiquement, la structure le rendant solidaire de la barge n'étant pas représentée.The connection device comprises in its lower part a pipe 1 of substantially constant diameter, as well as a transition zone 5 having a slight conicity located just below the zone of the floats. The top of the riser is guided by a guide system comprising a roller device 16 integral with the structure of said barge. These guide means allow said riser to slide along its longitudinal axis and guide its lateral movements in a horizontal plane perpendicular to said longitudinal axis of the riser. In Figures 1 to 12 the guide system is shown schematically, the structure making it integral with the barge is not shown.
La figure 13 est une coupe en vue de dessus d'une conduite 1 soumise à un courant 25 provoquant des tourbillons 26 en aval de ladite conduite. Le phénomène de tourbillon est représenté en position A. Le tourbillon prend naissance en cette position, se développe puis se détache de la structure et est entraîné ensuite dans le courant, en aval de la conduite. En même temps qu'un tourbillon se développe en position A, un autre tourbillon prend naissance en position B, qui évoluera par la suite. Cette position B est sensiblement symétrique de la position A par rapport à l'axe du courant. Les tourbillons sont ainsi générés alternativement dans les positions A et B. Cette instabilité est appelée "détachement tourbillonnaire alterné" . L'apparition d'un tourbillon s'accompagne d'un défaut de pression, et lorsqu'il se produit d'un même côté simultanément sur une hauteur suffisante, par exemple du côté A, les efforts latéraux engendrés tendent à déplacer la conduite vers la gauche c'est à dire vers la position C. La génération d'un nouveau tourbillon en position B entraînera ensuite un effort de pression vers la droite, c'est-à-dire vers la position D. Les efforts latéraux de pression vont ainsi se succéder de part et d'autre de la conduite. Lorsque la fréquence d'excitation liée à cette instabilité est proche des fréquences propres de la conduite, elle entraîne des vibrations de cette conduite. L'amorçage de ce phénomène de vibration est appelé "accrochage".Figure 13 is a sectional view from above of a pipe 1 subjected to a current 25 causing vortices 26 downstream of said pipe. The vortex phenomenon is represented in position A. The vortex begins in this position, develops then detaches from the structure and is then entrained in the current, downstream of the pipe. At the same time that a vortex develops in position A, another vortex begins in position B, which will evolve thereafter. This position B is substantially symmetrical with the position A with respect to the axis of the current. The vortices are thus generated alternately in positions A and B. This instability is called "alternating vortex detachment". The appearance of a vortex is accompanied by a pressure defect, and when it occurs simultaneously on the same side over a sufficient height, for example on the A side, the lateral forces generated tend to move the pipe to the left, ie to position C. The generation of a new vortex in position B will then cause a pressure force towards the right, that is to say towards position D. The lateral pressure forces will thus succeed one another on either side of the pipe. When the excitation frequency linked to this instability is close to the natural frequencies of the pipe, it causes vibrations of this pipe. The initiation of this vibration phenomenon is called "hooking".
Les caractéristiques de cette instabilité évoluent avec des paramètres liés à l'écoulement (vitesse) et à la géométrie de la conduite (diamètre). Il faut préciser que, dans certains cas bien particulier, la vibration s'effectue dans la direction du courant et non perpendiculairement, le détachement tourbillonnaire n'étant plus alors "alterné" mais "simultané", dans les positions A et B de la figure 13.The characteristics of this instability evolve with parameters related to the flow (speed) and to the geometry of the pipe (diameter). It should be noted that, in some very specific cases, the vibration takes place in the direction of the current and not perpendicularly, the vortex detachment then no longer being "alternated" but "simultaneous", in positions A and B of the figure 13.
Les figures 2, 3 et 4 sont des vues de côté d'une conduite 1 encastrée en pied et tensionné en tête par des moyens extérieurs non représentés, et guidé par un dispositif à rouleaux 16, en situation respectivement de repos (figure 2), et de vibration de type "guitare" respectivement en mode 1FIGS. 2, 3 and 4 are side views of a pipe 1 embedded at the bottom and tensioned at the head by external means not shown, and guided by a roller device 16, in the respective rest position (FIG. 2), and vibration type "guitar" respectively in mode 1
(figure 3) et en mode 2 (figure 4) .(figure 3) and in mode 2 (figure 4).
Dans les figures 3 et 4, les ventres 12 et nœuds 1 1 se forment dans des plans 10 situés sensiblement à L/2 ou L/4.In FIGS. 3 and 4, the bellies 12 and nodes 11 are formed in planes 10 located substantially at L / 2 or L / 4.
Les figures 5, 6 et 7 sont des vues de côté d'un riser 1 tensionné par des flotteurs 2 et guidé en tête par un dispositif à rouleaux 16, en situation respectivement de repos (figure 5) , et de vibration de type "guitare- pendule", respectivement en mode 1 (figure 6) et en mode 2 (figure 7) .FIGS. 5, 6 and 7 are side views of a riser 1 tensioned by floats 2 and guided at the head by a roller device 16, in respectively a state of rest (FIG. 5), and of vibration of the "guitar" type - pendulum ", respectively in mode 1 (figure 6) and in mode 2 (figure 7).
Les déformations ont été considérablement exagérées pour la clarté de la description, qui montre que les plans 10 dans lesquels se forment les nœuds 1 1 et les ventres 12 sont fortement décalés vers le haut. Sur la figure 6, le riser oscille entre les deux positions extrêmes 13a-13b représentées, alors que la figure 7 ne représente le riser que dans l'une de ses positions extrêmes. Sur la figure 5, on a représenté à droite du riser la variation sensiblement linéaire de la tension du riser le long de son axe longitudinal.The deformations have been considerably exaggerated for the clarity of the description, which shows that the planes 10 in which the nodes 11 and the bellies 12 are formed are strongly shifted upwards. In FIG. 6, the riser oscillates between the two extreme positions 13a-13b shown, while FIG. 7 represents the riser only in one of its extreme positions. In Figure 5, there is shown to the right of the riser the substantially linear variation of the riser voltage along its longitudinal axis.
La tension croît à partir du point de guidage. La tension est maximaleThe tension increases from the guide point. The tension is maximum
(Tmax) à la jonction de la zone des flotteurs avec la zone de transition 5. Puis, la tension décroît avec la profondeur dans la partie courante et confère au riser un mode de déformation de type "corde vibrante" (figures(Tmax) at the junction of the float area with the transition area 5. Then, the tension decreases with the depth in the current part and gives the riser a deformation mode of the "vibrating rope" type (figures
6 et 7) encore appelé "mode guitare". Dans la zone des flotteurs 4, la tension décroît lorsque l'on remonte vers la surface, pour s'inverser et devenir compression dans la partie émergée du riser au-dessus du flotteur supérieur et atteindre une compression maximale au-dessus du système de guidage en tête de puits. Il en résulte que la partie haute du riser se comporte comme un pendule pivotant autour d'un point fixe en tête de riser, ce qui fait la particularité de ce type de riser qui constitue un système couplé "pendule-corde vibrante" sous l'effet du courant et de la houle sur le riser et sur la barge.6 and 7) also called "guitar mode". In the zone of the floats 4, the tension decreases when one goes up towards the surface, to reverse and become compression in the emerged part of the riser above the upper float and to reach a maximum compression above the guidance system wellhead. As a result, the upper part of the riser behaves like a pendulum pivoting around a fixed point at the head of the riser, which is the particularity of this type of riser which constitutes a coupled "pendulum-vibrating rope" system under the effect of current and swell on the riser and the barge.
Dans les figures 9 à 12 sont présentés des dispositifs de stabilisation qui visent à réduire ou éliminer le comportement pendulaire de la partie haute du riser. Ces dispositifs de stabilisation sont localisés dans la zone des flotteurs 4 ou dans la zone de transition 5 "riser-flotteur" qui correspond à une zone où le diamètre de la conduite décroît progressivement vers le bas, jusqu'à atteindre la partie courante de la conduite, laquelle correspond à la partie de la conduite à diamètre sensiblement constant située en dessous de ladite zone de transition.In FIGS. 9 to 12, stabilization devices are presented which aim to reduce or eliminate the pendulum behavior of the upper part of the riser. These stabilization devices are located in the area of the floats 4 or in the transition zone 5 "riser-float" which corresponds to an area where the diameter of the pipe decreases progressively downward, until it reaches the current part of the pipe, which corresponds to the part of the pipe with a substantially constant diameter located below said transition zone.
Dans les figures 8 et 9 représentant la zone des flotteurs, les forces F de flottabilité et P de masse liée au centre de gravité de l'ensemble, respectivement sans masse additionnelle (figure 8) et avec une masse additionnelle 7 installée dans la partie basse du flotteur inférieur (figure 9). La masse additionnelle 7 est obtenue par une enceinte entourant le flotteur contenant un composé pondéreux tel que du minerais de fer. Il pourrait s'agir d'un flotteur lui-même rempli d'eau.In FIGS. 8 and 9 representing the area of the floats, the forces F of buoyancy and P of mass linked to the center of gravity of the assembly, respectively without additional mass (FIG. 8) and with an additional mass 7 installed in the lower part of the lower float (figure 9). The additional mass 7 is obtained by an enclosure surrounding the float containing a heavy compound such as iron ores. It could be a float itself filled with water.
Sur la figure 8, la masse de la zone des flotteurs correspond à PI .In Figure 8, the mass of the float area corresponds to PI.
La masse additionnelle 7 augmente la valeur de la masse de PI à P2 et abaisse le centre de gravité. Le moment de rappel de la force P2 est ainsi augmentée, ce qui a pour effet de stabiliser la conduite. La figure 10 est une vue de côté d'un riser 1 comportant des flotteurs 2, des stabilisateurs de type "hélice" 8 comprenant des rampes hélicoïdales sont installés sur le flotteur le plus bas, de préférence dans sa partie basse. Les hélices 8 pourraient avantageusement être installées sur la pièce constituant la zone de transition 5, située juste en dessous du dernier flotteur. La zone d'efficacité maximale se situe dans l'une de ces deux positions. Les hélices sont installées de manière très ponctuelle, par exemple sur une hauteur de trois ou 4 mètres. Chaque rampe hélicoïdale 8 ne réalise qu'une section angulaire partielle du contour du flotteur. Ces structures à géométrie tridimensionnelle rapportée à la surface du flotteur confèrent un double effet de stabilisation par absorption d'énergie et augmentation de la masse d'eau, voire également un troisième effet de stabilisation par abaissement du centre de gravité.The additional mass 7 increases the value of the mass from PI to P2 and lowers the center of gravity. The force recall moment P2 is thus increased, which has the effect of stabilizing the pipe. FIG. 10 is a side view of a riser 1 comprising floats 2, stabilizers of the "propeller" type 8 comprising helical ramps are installed on the lowest float, preferably in its lower part. The propellers 8 could advantageously be installed on the part constituting the transition zone 5, located just below the last float. The zone of maximum efficiency is in one of these two positions. The propellers are installed very punctually, for example on a height of three or 4 meters. Each helical ramp 8 produces only a partial angular section of the contour of the float. These structures with three-dimensional geometry related to the surface of the float confer a double stabilization effect by absorption of energy and increase in the mass of water, even also a third stabilization effect by lowering of the center of gravity.
La figure 1 1 est une vue de côté d'un riser 1 comportant des flotteurs 2, équipé d'un dispositif de stabilisation de type caisson perforé à turbulences 9, situé en dessous et en prolongement du flotteur le plus bas, par exemple dans la zone de transition, c'est-à-dire à une profondeur d'environ 50 à 100 m éloignée des effets de la houle. Ce caisson est constitué d'une simple enveloppe percée de trous de section variable ou non, solidaire du riser. La masse d'eau piégée à l'intérieur du caisson qui peut représenter 20 à 50 tonnes sera mise en mouvement lors des déplacements latéraux du riser et s'oppose par son inertie auxdits déplacements. Les ouvertures pratiquées dans le caisson autorisent des mouvements limités de l'eau piégée vers l'extérieur, puis vers l'intérieur, ce qui crée un amortissement complémentaire par absorption d'énergie et accroît ainsi considérablement l'effet stabilisateur.FIG. 11 is a side view of a riser 1 comprising floats 2, equipped with a stabilization device of the turbulent perforated box type 9, located below and in extension of the lowest float, for example in the transition zone, that is to say at a depth of about 50 to 100 m away from the effects of the swell. This box consists of a simple envelope pierced with holes of variable section or not, secured to the riser. The mass of water trapped inside the box which can represent 20 to 50 tonnes will be set in motion during lateral movements of the riser and is opposed by its inertia to said movements. The openings in the box allow limited movements of the trapped water outwards, then inwards, which creates additional damping by absorbing energy and thus considerably increases the stabilizing effect.
Enfin l'ajout de ce caisson en dessous des flotteurs confère également un troisième effet d'abaissement du centre de gravité.Finally, the addition of this box below the floats also gives a third effect of lowering the center of gravity.
La figure 12 est une vue de côté d'un riser 1 équipé de flotteurs 2 de formes extérieures variées dont le but est d'absorber l'énergie pour empêcher la formation de détachements tourbillonnaires conduisant à des effets d'accrochage.Figure 12 is a side view of a riser 1 equipped with floats 2 of various external shapes whose purpose is to absorb energy to prevent the formation of vortex detachments leading to latching effects.
En effet, les détachements tourbillonnaires se produisent sur les surfaces extérieures des flotteurs ou des conduites tel qu'expliqué dans la description de la figure 13. Lorsque les génératrices sont cylindriques (2a), les tourbillons 26 ont tendance à se former simultanément d'un même côté sur des longueurs variables. Dès que la longueur devient suffisante, par exemple 5 ou 10 mètres ou plus, les forces engendrées se cumulent et sont dirigées dans une même direction, ce qui provoque le phénomène "d'accrochage" conduisant à la mise en vibration du riser.Indeed, vortex detachments occur on the exterior surfaces of floats or pipes as explained in the description of FIG. 13. When the generatrices are cylindrical (2 a ), the vortices 26 tend to form simultaneously on the same side over variable lengths. As soon as the length becomes sufficient, for example 5 or 10 meters or more, the forces generated accumulate and are directed in the same direction, which causes the phenomenon of "hooking" leading to the vibration of the riser.
En supprimant les génératrices cylindriques du flotteur 2 et en les remplaçant par des formes variées telles que des cônes 2b ou des formes de révolution convexes 2d ou concaves 2c, les risques d'accrochage sont réduits, voire supprimés. Ces formes particulières peuvent aussi être des écrans extérieurs rajoutés à des bidons cylindriques conventionnels.By eliminating the cylindrical generators of the float 2 and replacing them with various shapes such as cones 2b or convex revolution shapes 2d or concave 2c, the risks of snagging are reduced or even eliminated. These particular shapes can also be external screens added to conventional cylindrical canisters.
Ces formes particulières sont avantageusement combinées avec d'autres dispositifs de stabilisation tel que le remplissage d'eau du flotteur le plus bas ou l'association avec un caisson perforé dans la zone de transition 5. These particular shapes are advantageously combined with other stabilization devices such as filling the water in the lowest float or combining it with a perforated box in the transition zone 5.

Claims

REVENDICATIONS
1. Dispositif de liaison fond-surface comportant au moins une conduite sous-marine (1) comprenant au moins un flotteur (2), de préférence une pluralité de flotteurs en chapelet, lesdits flotteurs consistant en des bidons entourant ladite conduite (1), localisés dans la partie haute immergée de la conduite, ladite conduite étant maintenue en surface par un dispositif de guidage, de préférence au niveau d'un support flottant (15), de flotteur, caractérisé en ce qu'il comprend au moins un dispositif stabilisateur (3) situé dans la partie supérieure de la conduite constituée par :1. Bottom-surface connection device comprising at least one underwater pipe (1) comprising at least one float (2), preferably a plurality of floats in a chain, said floats consisting of cans surrounding said pipe (1), located in the upper submerged part of the pipe, said pipe being held on the surface by a guide device, preferably at a floating support (15), float, characterized in that it comprises at least one stabilizing device (3) located in the upper part of the pipe consisting of:
- la partie basse de la zone des flotteurs (4), de préférence sur ou au niveau du flotteur le plus bas, et- the lower part of the float area (4), preferably on or at the level of the lowest float, and
- la zone de transition (5) entre les flotteurs (4) et la partie courante à diamètre sensiblement constant (6) de ladite conduite (1). - The transition zone (5) between the floats (4) and the running part with a substantially constant diameter (6) of said pipe (1).
2. Dispositif de liaison fond-surface selon la revendication 1 caractérisé en ce que le dispositif stabilisateur comprend au moins un dispositif choisi parmi :2. bottom-surface connection device according to claim 1 characterized in that the stabilizing device comprises at least one device chosen from:
- un dispositif d'absorption d'énergie (7, 8, 9),- an energy absorption device (7, 8, 9),
- un dispositif augmentant la masse d'eau entraînée au cours de son mouvement (7, 9), et- a device increasing the mass of water entrained during its movement (7, 9), and
- un dispositif abaissant le centre de gravité (7,9) de ladite partie supérieure de la conduite.- A device lowering the center of gravity (7,9) of said upper part of the pipe.
3. Dispositif de liaison fond-surface selon la revendication 2, caractérisé en ce que ledit dispositif stabilisateur cumule au moins deux, de préférence les trois, des effets choisis parmi :3. bottom-surface connection device according to claim 2, characterized in that said stabilizing device combines at least two, preferably all three, of the effects chosen from:
- l'absorption d'énergie (7, 8, 9),- energy absorption (7, 8, 9),
- l'augmentation de la masse d'eau entraînée au cours de son mouvement (7, 9), et- the increase in the mass of water entrained during its movement (7, 9), and
- l'abaissement du centre de gravité (7, 9) de ladite partie supérieure de la conduite.- Lowering the center of gravity (7, 9) of said upper part of the pipe.
4. Dispositif de liaison fond-surface selon l'une des revendications 1 à 3, caractérisé en ce que ledit dispositif comprend un élément de structure augmentant la surface de contact avec l'eau (8) ou créant une surface de contact avec l'eau non cylindrique par rapport à l'axe de ladite conduite (2b,4. bottom-surface connection device according to one of claims 1 to 3, characterized in that said device comprises a structural element increasing the contact surface with water (8) or creating a surface of contact with non-cylindrical water relative to the axis of said pipe ( 2b ,
5. Dispositif selon l'une des revendications 1 à 4, caractérisé en ce que ledit dispositif stabilisateur comprend la forme non-cylindrique (2b, 2C, 2d) de la surface extérieure d'un flotteur (2) ou d'une partie de conduite (5) .5. Device according to one of claims 1 to 4, characterized in that said stabilizer means comprises the non-cylindrical shape (2 b, 2 C, 2 d) of the outer surface of a float (2) or pipe part (5).
6. Dispositif selon l'une des revendications 1 à 5 caractérisé en ce que ledit dispositif stabilisateur comprend au moins une rampe hélicoïdale (8) entourant un dit flotteur (2) ou ladite conduite (1) . 6. Device according to one of claims 1 to 5 characterized in that said stabilizing device comprises at least one helical ramp (8) surrounding a said float (2) or said pipe (1).
7. Dispositif selon l'une des revendications 1 à 6 caractérisé en ce que ledit dispositif stabilisateur comprend un caisson coaxial entourant ladite conduite dont la surface extérieure comprend des perforations (9) .7. Device according to one of claims 1 to 6 characterized in that said stabilizing device comprises a coaxial box surrounding said pipe, the outer surface of which comprises perforations (9).
8. Dispositif selon l'une des revendications 1 à 7 caractérisé en ce que le dispositif stabilisateur comprend une masse additionnelle (7) située dans ou autour d'un flotteur (2) ou entourant ladite conduite (1) .8. Device according to one of claims 1 to 7 characterized in that the stabilizing device comprises an additional mass (7) located in or around a float (2) or surrounding said pipe (1).
9. Dispositif selon la revendication 8 caractérisé en ce qu'il comprend un flotteur partiellement rempli d'eau, de préférence le flotteur le plus bas.9. Device according to claim 8 characterized in that it comprises a float partially filled with water, preferably the lowest float.
10. Dispositif selon l'une des revendications 1 à 9 caractérisé en ce que la zone des flotteurs (4) comprend plusieurs flotteurs (2) , de préférence au moins quatre.10. Device according to one of claims 1 to 9 characterized in that the area of the floats (4) comprises several floats (2), preferably at least four.
1 1. Dispositif selon l'une des revendications 1 à 10 caractérisé en ce que ledit dispositif stabilisateur est situé dans la partie basse de la zone des flotteurs (4), de préférence sur ou au niveau du flotteur le plus bas. 1 1. Device according to one of claims 1 to 10 characterized in that said stabilizing device is located in the lower part of the area of the floats (4), preferably on or at the level of the lowest float.
12. Dispositif selon l'une des revendications 1 à 10 caractérisé en ce que ledit dispositif stabilisateur est situé dans ladite zone de transition (5) , de préférence juste dessous le flotteur le plus bas.12. Device according to one of claims 1 to 10 characterized in that said stabilizing device is located in said transition zone (5), preferably just below the lowest float.
13. Dispositif selon la revendication 12 caractérisé en ce que la zone des flotteurs comprend plusieurs flotteurs dont les surfaces extérieures présentent des formes non-cylindriques différentes dont la génératrice peut être droite (2b) ou courbe (2C, 2d) .13. Device according to claim 12 characterized in that the area of the floats comprises several floats whose outer surfaces have different non-cylindrical shapes whose generator can be straight (2b) or curved (2 C , 2d).
14. Dispositif de liaison fond-surface selon l'une des revendications 1 à 13 caractérisé en ce qu'il comprend une pluralité de dites conduites sous-marines regroupées en faisceaux. 14. A bottom-surface connection device according to one of claims 1 to 13 characterized in that it comprises a plurality of said underwater pipes grouped in bundles.
EP01907665A 2000-01-24 2001-01-22 Seafloor-surface linking device comprising a stabilising element Expired - Lifetime EP1250510B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
FR0000865A FR2804162B1 (en) 2000-01-24 2000-01-24 BASE-SURFACE CONNECTION DEVICE HAVING A STABILIZER DEVICE
FR0000865 2000-01-24
PCT/FR2001/000203 WO2001053651A1 (en) 2000-01-24 2001-01-22 Seafloor-surface linking device comprising a stabilising element

Publications (2)

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EP1250510A1 true EP1250510A1 (en) 2002-10-23
EP1250510B1 EP1250510B1 (en) 2005-10-26

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EP01907665A Expired - Lifetime EP1250510B1 (en) 2000-01-24 2001-01-22 Seafloor-surface linking device comprising a stabilising element

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US (1) US6712559B2 (en)
EP (1) EP1250510B1 (en)
KR (1) KR20020081272A (en)
AT (1) ATE307956T1 (en)
AU (1) AU2001235578A1 (en)
BR (1) BR0107712A (en)
DE (1) DE60114365D1 (en)
FR (1) FR2804162B1 (en)
NO (1) NO20023420L (en)
OA (1) OA12140A (en)
WO (1) WO2001053651A1 (en)

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Also Published As

Publication number Publication date
BR0107712A (en) 2002-11-19
FR2804162B1 (en) 2002-06-07
EP1250510B1 (en) 2005-10-26
KR20020081272A (en) 2002-10-26
OA12140A (en) 2006-05-05
AU2001235578A1 (en) 2001-07-31
ATE307956T1 (en) 2005-11-15
NO20023420D0 (en) 2002-07-16
US20030000705A1 (en) 2003-01-02
US6712559B2 (en) 2004-03-30
FR2804162A1 (en) 2001-07-27
NO20023420L (en) 2002-07-16
DE60114365D1 (en) 2005-12-01
WO2001053651A1 (en) 2001-07-26

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