WO1992010398A1 - Semi-submersible platform with porous pontoons - Google Patents

Semi-submersible platform with porous pontoons Download PDF

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Publication number
WO1992010398A1
WO1992010398A1 PCT/FR1991/000963 FR9100963W WO9210398A1 WO 1992010398 A1 WO1992010398 A1 WO 1992010398A1 FR 9100963 W FR9100963 W FR 9100963W WO 9210398 A1 WO9210398 A1 WO 9210398A1
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WO
WIPO (PCT)
Prior art keywords
semi
pontoons
porous
submersible platform
walls
Prior art date
Application number
PCT/FR1991/000963
Other languages
French (fr)
Inventor
Bernard Molin
Original Assignee
Institut Français Du Petrole
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 Institut Français Du Petrole filed Critical Institut Français Du Petrole
Priority to BR919106221A priority Critical patent/BR9106221A/en
Publication of WO1992010398A1 publication Critical patent/WO1992010398A1/en
Priority to GB9217049A priority patent/GB2257664B/en
Priority to NO923155A priority patent/NO308517B1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B35/00—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for
    • B63B35/44—Floating buildings, stores, drilling platforms, or workshops, e.g. carrying water-oil separating devices
    • B63B35/4413—Floating drilling platforms, e.g. carrying water-oil separating devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
    • B63B1/02—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement
    • B63B1/10—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with multiple hulls
    • B63B1/107—Semi-submersibles; Small waterline area multiple hull vessels and the like, e.g. SWATH
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B39/00—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude
    • B63B39/005—Equipment to decrease ship's vibrations produced externally to the ship, e.g. wave-induced vibrations
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B39/00—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude
    • B63B39/06—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude to decrease vessel movements by using foils acting on ambient water
    • B63B2039/067—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude to decrease vessel movements by using foils acting on ambient water effecting motion dampening by means of fixed or movable resistance bodies, e.g. by bilge keels

Definitions

  • the present invention relates to a semi-submersible platform usable for example for production at sea.
  • This type of structure usually consists of elongated elements with a vertical axis (or columns) partly submerged, and elongated elements totally submerged with a horizontal axis, called pontoons.
  • These elements which are of variable number, can be arranged together in different ways to form the framework of a semi-submersible platform.
  • the structures thus formed generally support a bridge on which is attached equipment specific to the function for which the platform is intended.
  • a static criterion concerns for example the hydrostatic stability constraint which mainly conditions the section and the spacing of the columns.
  • the columns thus dimensioned are generally of large section.
  • the dynamic criteria notably linked to the swell periods, imply that the proper periods of the roll, pitch and heave structure are located well beyond said swell periods.
  • Another dynamic criterion relates to the balancing period, that is to say the period during which a complete cancellation of the vertical forces acting on the columns and pontoons is obtained.
  • a given balancing period is obtained which must be an upper limit of the swell periods usually encountered in a geographical area. For example, in the North Sea, the sizing of semi-submersible platforms must be such that their balancing period is between 18 and 20 seconds. To meet these criteria, the pontoons of semi-submersible platforms must be large and usually represent 70 to 80% of the total volume submerged.
  • the object of the present invention is to remedy these bulk problems in particular, by proposing a semi-submersible structure of reduced dimensions compared to the structures. conventional, and which of course also satisfies the sizing criteria set out above.
  • the present invention relates to a semi-submersible platform of the type defined at the head of the description and of which, in accordance with the invention, at least some of the pontoons have porous walls.
  • the porosity is notably achieved by a large number of openings in the walls; the openings can be perforations of any shape, slots, etc.
  • the porosity rate that is to say the ratio of the surface area of the openings to the total surface area of the walls of each pontoon, is preferably between 10 and 30.
  • FIG. 1 is a top view of a model used to show the features of a porous pontoon
  • FIG. 2 is a front view of the model of FIG. 1,
  • FIG. 5 is a top view of an embodiment of the invention.
  • FIG. 6 and 7 each show in perspective a geometry of a porous pontoon according to the invention.
  • Figures 1 and 2 show a model used to highlight certain physical features of a structure provided with a porous element.
  • the model taken here as an example, however, is entirely representative of an actual platform structure semi-submersible with particular regard to its hydrodynamic behavior.
  • the model almost completely submerged, consists of a first cylinder 1 of horizontal axis Y, porous, that is to say pierced with holes, slots or other small openings.
  • a second cylinder 2 of vertical axis Z is connected to the first, substantially in the middle.
  • the diameter of the second cylinder 2 is somewhat greater than that of the first.
  • the porous pontoons according to the invention are provided with openings on each of their walls.
  • pressure drops proportional to the square of the relative speed of the flow which passes through it are created, hence a very significant damping effect which considerably limits the phenomena of resonance.
  • FIG. 3 illustrates particularly well the phenomenon of damping generated by porous pontoons.
  • the section of the porous pontoons according to the invention can be smaller than that of the columns.
  • the manufacturing cost of the porous pontoons themselves can be significantly reduced because the porous pontoons no longer have to resist Hydrostatic pressure.
  • the pressure differences which apply to the perforated plates are indeed much less than the hydrostatic pressure.
  • porous pontoons which lose their function of buoyancy, however, continue to participate in the structural stiffness of the assembly, while playing a non-negligible role of shock absorber.
  • the damping provided by the porous pontoons in fact makes it possible to limit, or even eliminate, the resonance frequencies of the structure in pi Lon compassion, that is to say at the level of the movements of vertical translation as shown in the figure. 3. In addition, this damping acts on the horizontal movements of the structure.
  • This characteristic allows the height of the bridge, i.e. The distance between The emerged platform and the water level.
  • the height gain thus obtained is of the order of 50% or more.
  • the platforms provided with porous pontoons are therefore of reduced dimensions compared to the conventional platforms:
  • a platform according to the invention allows substantial gains in terms of anchoring, more specifically in terms of the dimensioning of the anchoring lines and of the transfer columns or flexible risers.
  • FIG. 5 An exemplary embodiment of a semi-submersible platform according to the invention is given in FIG. 5.
  • four columns 3 are arranged at the four corners of a square, each side of which is formed by a pontoon porous 4 fully submerged.
  • Any type of plate or support element can be supported, out of the water, by this basic structure.
  • the anchoring of such structures can be carried out in any manner known per se.
  • the section of the porous pontoons can be square, as shown in FIG. 7, or even circular as shown in FIG. 8.
  • the present invention will be more particularly used, in the offshore field, for small production supports with flexible risers.
  • the present invention will be more particularly used, in the offshore field, for small production supports with flexible risers.

Abstract

Semi-submersible platform comprised particularly of semi-immersed columns and totally immersed elongate elements or pontoons (4) having a substantially horizontal axis, at least some of them having porous walls, the porosity being obtained by a large number of small holes in said walls. The porosity degree, in other words the ratio between the total surface of the holes and the total surface of the walls is preferably at the most equal to 30 %.

Description

PLATE-FORME SEMI-SUBMERSIBLE A PONTONS POREUXSEMI-SUBMERSIBLE POROUS PONTOON PLATFORM
La présente invention concerne une plate-forme semi-submersible utilisable par exemple pour la production en mer.The present invention relates to a semi-submersible platform usable for example for production at sea.
Ce type de structure est habituellement constitué d'éléments allongés à axe vertical (ou colonnes) en partie immergés, et d'éléments allongés totalement immergés, à axe horizontal, appelés pontons. Ces éléments, qui sont en nombre variable, peuvent être agencés entre eux de différentes façons pour former l'ossature d'une plate-forme semi-submersible.This type of structure usually consists of elongated elements with a vertical axis (or columns) partly submerged, and elongated elements totally submerged with a horizontal axis, called pontoons. These elements, which are of variable number, can be arranged together in different ways to form the framework of a semi-submersible platform.
Les structures ainsi formées supportent généralement un pont sur lequel est arrimé un équipement spécifique à la fonction à laquelle est destinée la plate-forme.The structures thus formed generally support a bridge on which is attached equipment specific to the function for which the platform is intended.
De telles structures sont par exemple divulguées par les documents US-A-4.112.864, US-A-3.949.693 ou encore US-A-3.967.572.Such structures are for example disclosed by documents US-A-4,112,864, US-A-3,949,693 or even US-A-3,967,572.
Pour obtenir le maintien de ce type de plate-forme au-dessus d'un point précis fixe au fond de l'eau, plusieurs systèmes de positionnement sont utilisés. Des câbles souples peuvent relier des points d'ancrage au fond de l'eau et des points de la plate-forme. Il existe aussi des systèmes dits "de positionnement dynamique" constitués de propulseurs fixés à la plate-forme et destinés à ramener celle-ci vers sa position d'origine dès qu'une dérive est constatée.To maintain this type of platform above a specific fixed point at the bottom of the water, several positioning systems are used. Flexible cables can connect anchor points to the bottom of the water and points on the platform. There are also so-called "dynamic positioning" systems made up of thrusters fixed to the platform and intended to bring the latter back to its original position as soon as a drift is observed.
Dans le cas de production de pétrole, une ou plusieurs conduites flexibles ou "riser" relient les puits à la plate-forme et assurent la fonction de production proprement dite. En outre, les structures semi-submersibles doivent affronter des états de mer extrêmement difficiles. En mer du Nord par exemple, des dénivellations de "crête à creux" de l'ordre de 30 mètres sont à envisager. De telles structures sont donc très sollicitées et doivent en particulier présenter une résistance structurelle élevée.In the case of oil production, one or more flexible lines or "riser" connect the wells to the platform and ensure the production function itself. In addition, semi-submersible structures have to face extremely difficult sea conditions. In the North Sea, for example, drop-offs from "crest to trough" of the order of 30 meters are to be considered. Such structures are therefore very stressed and must in particular have a high structural strength.
Le dimensionnement des différents éléments constituant ces installations est donc particulièrement délicat et doit obéir à un certain nombre de critères statiques et dynamiques.The dimensioning of the various elements constituting these installations is therefore particularly delicate and must obey a certain number of static and dynamic criteria.
Un critère d'ordre statique concerne par exemple la contrainte de stabilité hydrostatique qui conditionne principalement la section et l'espacement des colonnes. Les colonnes ainsi dimensionnées sont généralement de section importante.A static criterion concerns for example the hydrostatic stability constraint which mainly conditions the section and the spacing of the columns. The columns thus dimensioned are generally of large section.
Les critères dynamiques, liés notamment aux périodes de houles, impliquent que les périodes propres de la structure en roulis, tangage et pilonnement soient situées bien au-delà desdites périodes de houle. Un autre critère dynamique est relatif à la période d'équilibrage, c'est-à-dire la période à laquelle on obtient une annulation complète des efforts verticaux agissant sur les colonnes et les pontons. En choississant de façon appropriée les dimensions des colonnes et des pontons, on obtient une période d'équilibrage donnée qui devra être une limite supérieure des périodes de houle rencontrées habituellement dans une zone géographique. Par exemple, en mer du Nord, le dimensionnement des plates-formes semi-submersibles doit être tel que leur période d'équilibrage se situe entre 18 et 20 secondes. Pour satisfaire ces critères, les pontons des plates- formes semi-submersibles doivent être volumineux et représentent habituellement de 70 à 80 % du volume total immergé.The dynamic criteria, notably linked to the swell periods, imply that the proper periods of the roll, pitch and heave structure are located well beyond said swell periods. Another dynamic criterion relates to the balancing period, that is to say the period during which a complete cancellation of the vertical forces acting on the columns and pontoons is obtained. By appropriately choosing the dimensions of the columns and pontoons, a given balancing period is obtained which must be an upper limit of the swell periods usually encountered in a geographical area. For example, in the North Sea, the sizing of semi-submersible platforms must be such that their balancing period is between 18 and 20 seconds. To meet these criteria, the pontoons of semi-submersible platforms must be large and usually represent 70 to 80% of the total volume submerged.
Les plates-formes semi-submersibles réalisées jusqu'à présent en fonction notamment des critères énoncés ci-dessus, sont donc d'assez grandes dimensions d'où des problèmes de délais, de coûts qui peuvent s'avérer gênants dans certains cas.The semi-submersible platforms produced up to now based in particular on the criteria set out above, are therefore of relatively large dimensions, hence problems of deadlines and costs which can prove to be troublesome in certain cases.
La présente invention a pour but de remédier en particulier à ces problèmes d'encombrement, en proposant une structure semi-submersible de dimensions réduites par rapport aux structures classiques, et qui bien entendu satisfasse tout autant les critères de dimensionnement énoncés plus haut.The object of the present invention is to remedy these bulk problems in particular, by proposing a semi-submersible structure of reduced dimensions compared to the structures. conventional, and which of course also satisfies the sizing criteria set out above.
La présente invention concerne une plate-forme semi- submersible du type défini en tête de la description et dont, conformément à l'invention, certains au moins des pontons présentent des parois poreuses.The present invention relates to a semi-submersible platform of the type defined at the head of the description and of which, in accordance with the invention, at least some of the pontoons have porous walls.
La porosité est notamment réalisée par un grand nombre d'ouvertures dans les parois ; les ouvertures peuvent être des perforations de toute forme, des fentes... Le taux de porosité, c'est-à-dire le rapport de la surface des ouvertures à la surface totale des parois de chaque ponton, est de préférence compris entre 10 et 30 .The porosity is notably achieved by a large number of openings in the walls; the openings can be perforations of any shape, slots, etc. The porosity rate, that is to say the ratio of the surface area of the openings to the total surface area of the walls of each pontoon, is preferably between 10 and 30.
La présente invention trouvera une application particulière en tant que plate-forme ou "support" de production. D'autres caractéristiques et avantages de la présente invention ressortiront mieux à la lecture de la description qui va suivre, faite de manière illustrative et non limitative, en référence aux dessins annexés sur lesquels :The present invention will find particular application as a production platform or "support". Other characteristics and advantages of the present invention will emerge more clearly on reading the description which follows, given in an illustrative and nonlimiting manner, with reference to the appended drawings in which:
- la figure 1 est une vue de dessus d'un modèle utilisé pour montrer les particularités d'un ponton poreux,- Figure 1 is a top view of a model used to show the features of a porous pontoon,
- la figure 2 est une vue de face du modèle de la figure 1,FIG. 2 is a front view of the model of FIG. 1,
- la figure 3 montre les courbes des fonctions de transfert en pi lonne ent obtenues pour Le modèle représenté sur Les figures 1 et 2, - La figure 4 montre Les courbes des fonctions de transfert en pi Lon¬ nement relatif obtenues pour le modèle donné par Les figures 1 et 2,- Figure 3 shows the curves of the transfer functions in pi lonne obtained for the model shown in Figures 1 and 2, - Figure 4 shows the curves of the transfer functions in pi Relative lon¬ ment obtained for the model given by Figures 1 and 2,
- la figure 5 est une vue de dessus d'un mode de réalisation de L'invention, etFIG. 5 is a top view of an embodiment of the invention, and
- Les figures 6 et 7 montrent chacune en perspective une géométrie d'un ponton poreux selon l'invention.- Figures 6 and 7 each show in perspective a geometry of a porous pontoon according to the invention.
Les figures 1 et 2 montrent un modèle utilisé pour mettre en évidence certaines particularités physiques d'une structure pourvue d'un élément poreux. Le modèle pris ici comme exemple, est cependant tout à fait représentatif d'une structure réelle de plate-forme semi-submersible en ce qui concerne en particulier son comportement hydrodynamique.Figures 1 and 2 show a model used to highlight certain physical features of a structure provided with a porous element. The model taken here as an example, however, is entirely representative of an actual platform structure semi-submersible with particular regard to its hydrodynamic behavior.
Le modèle, presque totalement immergé, est constitué d'un premier cylindre 1 d'axe horizontal Y, poreux, c'est-à-dire percé de trous, fentes ou autres petites ouvertures.The model, almost completely submerged, consists of a first cylinder 1 of horizontal axis Y, porous, that is to say pierced with holes, slots or other small openings.
Un second cylindre 2 d'axe vertical Z est raccordé au premier, substantiellement en son milieu. Le diamètre du second cylindre 2 est quelque peu supérieur à celui du premier.A second cylinder 2 of vertical axis Z is connected to the first, substantially in the middle. The diameter of the second cylinder 2 is somewhat greater than that of the first.
Une étude a été faite, à partir de ce modèle, sur le mouvement de translation verticale appelé "pi Lonnement", dû à L'action de la houle.A study was made, from this model, on the vertical translational movement called "pi Lonnement", due to the action of the swell.
Le mouvement de translation horizontale, dans la direction de propagation de La houle, et appelé "cavale ent", a également été étudié. La réponse d'une structure flottante, notamment vis-à-vis du p lonnement, est en effet très significative pour son dimension¬ nement et l'évaluation de ses performances.The horizontal translational movement, in the direction of propagation of the swell, and called "cavale ent", was also studied. The response of a floating structure, in particular vis-à-vis the structure, is indeed very significant for its size and the evaluation of its performance.
De façon avantageuse, les pontons poreux selon l'invention sont pourvus d'ouverturessur chacunes de leurs parois. Ainsi, avec un ponton poreux selon l'invention, des pertes de charge proportionnelles au carré de La vitesse relative de l'écoulement qui le traverse, sont créées, d'où un effet amortisseur très important qui Limite considérablement les phénomènes de résonnance.Advantageously, the porous pontoons according to the invention are provided with openings on each of their walls. Thus, with a porous pontoon according to the invention, pressure drops proportional to the square of the relative speed of the flow which passes through it, are created, hence a very significant damping effect which considerably limits the phenomena of resonance.
La figure 3 illustre particulièrement bien le phénomène d'amortissement engendré par les pontons poreux. En effet, La courbeFigure 3 illustrates particularly well the phenomenon of damping generated by porous pontoons. The curve
30 en traits pleins représente La fonction de transfert en piLonnement d'un ponton étanche. On remarque nettement une résonnance, pour des périodes de houle d'environ 16 ou 17 secondes.30 in solid lines represents the function of transfer by trampling of a watertight pontoon. We clearly notice a resonance, for swell periods of about 16 or 17 seconds.
Cette résonnance est avantageusement limitée, voire supprimée si l'on considère des pontons poreux dont le comportement est représenté par les courbes en pointillé 31 à 33 de la figure 3. Ces trois courbes correspondent à La réponse de pontons ayant respectivement des porosités de 10, 20 et 30 %. Une porosité de 30 % supprime totalement Le phénomène de résonnance. IL ressort de ce qui précède qu'au plan hydrodynamique, le taux de porosité des pontons est un paramètre prépondérant. La forme des petites ouvertures par contre ne semble pas significative, de même que La forme de la section des pontons.This resonance is advantageously limited, or even eliminated if we consider porous pontoons whose behavior is represented by the dotted curves 31 to 33 in FIG. 3. These three curves correspond to the response of pontoons having porosities of 10 respectively, 20 and 30%. A porosity of 30% completely removes the phenomenon of resonance. It follows from the above that at the hydrodynamic level, the pontoon porosity rate is a paramount parameter. The shape of the small openings on the other hand does not seem significant, as is the shape of the section of the pontoons.
A l'inverse des plates-formes semi-submersibles traditionnelles et de façon avantageuse, la section des pontons poreux selon L'invention peut être inférieure à celle des colonnes.Unlike traditional semi-submersible platforms and advantageously, the section of the porous pontoons according to the invention can be smaller than that of the columns.
Par ailleurs, par rapport à une structure classique, c'est-à-dire pourvue de pontons à parois pleines, le coût de fabrication des pontons poreux eux-mêmes, peut être notablement réduit car les pontons poreux n'ont plus à résister à La pression hydro¬ statique. Les différences de pression qui s'appliquent sur les plaques perforées sont en effet bien inférieures à La pression hydrostatique.Furthermore, compared to a conventional structure, that is to say provided with pontoons with solid walls, the manufacturing cost of the porous pontoons themselves, can be significantly reduced because the porous pontoons no longer have to resist Hydrostatic pressure. The pressure differences which apply to the perforated plates are indeed much less than the hydrostatic pressure.
En outre, Les pontons poreux qui perdent Leur fonction de flottab Lité, continuent cependant de participer à la raideur structurelle de l'ensemble, tout en jouant un rôle non négligeable d'amortisseur.In addition, the porous pontoons which lose their function of buoyancy, however, continue to participate in the structural stiffness of the assembly, while playing a non-negligible role of shock absorber.
L'amortissement apporté par les pontons poreux permet en effet de Limiter, voire d'éliminer, les fréquences de résonnance de La structure en pi Lonnement, c'est-à-dire au niveau des mouvements de translation verticale comme il ressort de la figure 3. De plus, cet amortissement agit sur Les mouvements horizontaux de la structure.The damping provided by the porous pontoons in fact makes it possible to limit, or even eliminate, the resonance frequencies of the structure in pi Lonnement, that is to say at the level of the movements of vertical translation as shown in the figure. 3. In addition, this damping acts on the horizontal movements of the structure.
L'amortissement créé par Les pontons poreux tend en effet à faire disparaitre les oscillations basse fréquence dans le plan horizontal. Cette caractéristique permet donc d'associer un ancrage moins coûteux aux plates-formes selon l'invention.The damping created by porous pontoons tends to make the low frequency oscillations disappear in the horizontal plane. This characteristic therefore makes it possible to associate a less costly anchoring with the platforms according to the invention.
Par ailleurs, des études ont révélé que, comme le montre la figure 4, le pi lonnement relatif, c'est-à-dire la translation verticale relative de la structure flottante par rapport à La surface Libre, notamment aux fortes périodes de houle (périodes supérieures à 12 ou 13 secondes), diminue très nettement en remplaçant des pontons à parois pleines (courbe 40), par des pontons de porosité respectivement égale à 10, 20 et 30 % (courbes 41, 42, 43).In addition, studies have revealed that, as shown in Figure 4, the relative tremor, that is to say the relative vertical translation of the floating structure with respect to the free surface, especially during strong swell periods ( periods greater than 12 or 13 seconds), decreases very markedly by replacing pontoons with solid walls (curve 40), by pontoons with porosity respectively equal to 10, 20 and 30% (curves 41, 42, 43).
Cette caractéristique permet de diminuer La hauteur du pont, c'est-à-dire La distance entre La plate-forme émergée et le niveau d'eau. Le gain en hauteur ainsi obtenu est de l'ordre de 50 % ou plus.This characteristic allows the height of the bridge, i.e. The distance between The emerged platform and the water level. The height gain thus obtained is of the order of 50% or more.
Les plates-formes pourvues de pontons poreux sont donc de dimensions réduites par rapport aux plates-formes classiques :The platforms provided with porous pontoons are therefore of reduced dimensions compared to the conventional platforms:
- au niveau de la section des pontons, et- at the pontoon section, and
- au niveau de la hauteur du pont.- at the height of the bridge.
De plus, une plate-forme selon l'invention permet des gains substantiels au niveau de l'ancrage, plus spécifiquement au niveau du dimensionnement des lignes d'ancrage et des colonnes de transfert ou risers flexibles.In addition, a platform according to the invention allows substantial gains in terms of anchoring, more specifically in terms of the dimensioning of the anchoring lines and of the transfer columns or flexible risers.
Un exemple de réalisation d'une plate-forme semi- submersible selon l'invention est donné par la figure 5. Selon ce mode de réalisation, quatre colonnes 3 sont disposées aux quatre coins d'un carré dont chaque côté est formé par un ponton poreux 4 totalement immergé.An exemplary embodiment of a semi-submersible platform according to the invention is given in FIG. 5. According to this embodiment, four columns 3 are arranged at the four corners of a square, each side of which is formed by a pontoon porous 4 fully submerged.
Tout type de plaque ou d'élément support peut être supporté, hors de l'eau, par cette structure de base.Any type of plate or support element can be supported, out of the water, by this basic structure.
IL est également envisageable, sans sortir du cadre de l'invention, de concevoir une structure pourvue à la fois de pontons poreux et de pontons étanches.It is also possible, without departing from the scope of the invention, to design a structure provided with both porous pontoons and watertight pontoons.
L'ancrage de telles structures peut être réalisé de n'importe quelle manière connue en soi.The anchoring of such structures can be carried out in any manner known per se.
Par ailleurs, comme il a déjà été dit, la section des pontons poreux peut être carrée, comme représenté sur la figure 7, ou encore circulaire comme montré par la figure 8.Furthermore, as has already been said, the section of the porous pontoons can be square, as shown in FIG. 7, or even circular as shown in FIG. 8.
D'autres types de sections sont envisageables, l'exemple le plus facilement réalisable étant cependant celui des sections les plus couramment utilisées de façon classique, à savoir la section d'un rectangle à angles biseautés.Other types of sections can be envisaged, the most easily achievable example however being that of the sections most commonly used in a conventional manner, namely the section of a rectangle with beveled angles.
De façon préférentielle, mais non Limitative, la présente invention sera plus particulièrement utilisée, dans le domaine offshore, pour des petits supports de production avec risers flexibles. Bien entendu, L'homme de L'art sera en mesure d'imaginer, à partir de La description qui vient d'être donnée à titre illustratif et nullement limitatif, diverses variantes et modifications ne sortant pas du cadre de L'invention.Preferably, but not limitation, the present invention will be more particularly used, in the offshore field, for small production supports with flexible risers. Of course, those skilled in the art will be able to imagine, from the description which has just been given by way of illustration and in no way limitative, various variants and modifications not departing from the scope of the invention.
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Claims

R E V E N D I C A T I O N S
1. - Plate-forme semi-submersible constituée notamment de colonnes semi-immergées et d'éléments allongés, ou pontons, d'axe sensiblement horizontal, totalement immergés, caractérisée en ce que certains au moins desdits pontons présentent des parois poreuses, La porosité étant réalisée par un grand nombre de petites ouvertures à travers toutes lesdites parois.1. - Semi-submersible platform consisting in particular of semi-submerged columns and elongated elements, or pontoons, of substantially horizontal axis, fully submerged, characterized in that at least some of said pontoons have porous walls, The porosity being produced by a large number of small openings through all of said walls.
2. - Plate-forme semi-submersible selon la revendication2. - semi-submersible platform according to claim
1, caractérisée en ce que Le taux de porosité, c'est-à-dire le rapport de la surface totale des ouvertures à la surface totale des parois est au plus égal à 30 %.1, characterized in that the porosity rate, that is to say the ratio of the total area of the openings to the total area of the walls is at most equal to 30%.
3. - Plate-forme semi-submersible selon la revendication3. - semi-submersible platform according to claim
2, caractérisée en ce que ledit taux de porosité est compris entre 10 et 30 Y..2, characterized in that said porosity rate is between 10 and 30 Y ..
4. - Plate-forme semi-submersible selon l'une quelconque des revendications précédentes, caractérisée en ce que les petites ouvertures sont des fentes.4. - Semi-submersible platform according to any one of the preceding claims, characterized in that the small openings are slots.
5. - Utilisation de la plate-forme semi-submersible selon L'une quelconque des revendications précédentes, pour réaliser une unité offshore de support de production. 5. - Use of the semi-submersible platform according to any one of the preceding claims, for producing an offshore production support unit.
6. - Plate-forme selon l'une quelconque des revendications6. - Platform according to any one of the claims
1 à 4, caractérisée en ce qu'elle comprend quatre colonnes et quatre pontons, dont deux au moins sont poreux. 1 to 4, characterized in that it comprises four columns and four pontoons, at least two of which are porous.
PCT/FR1991/000963 1990-12-13 1991-12-02 Semi-submersible platform with porous pontoons WO1992010398A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BR919106221A BR9106221A (en) 1990-12-13 1991-12-02 SEMI-SUBMERSIBLE PLATFORM WITH POROUS POINTS
GB9217049A GB2257664B (en) 1990-12-13 1992-08-11 Semi-submersible platforms with porous pontoons
NO923155A NO308517B1 (en) 1990-12-13 1992-08-12 Semi-submersible platform with porous pontoons

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR90/15749 1990-12-13
FR9015749A FR2670459B1 (en) 1990-12-13 1990-12-13 SEMI-SUBMERSIBLE PLATFORM WITH POROUS PONTOONS.

Publications (1)

Publication Number Publication Date
WO1992010398A1 true WO1992010398A1 (en) 1992-06-25

Family

ID=9403297

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/FR1991/000963 WO1992010398A1 (en) 1990-12-13 1991-12-02 Semi-submersible platform with porous pontoons

Country Status (5)

Country Link
BR (1) BR9106221A (en)
FR (1) FR2670459B1 (en)
GB (1) GB2257664B (en)
NO (1) NO308517B1 (en)
WO (1) WO1992010398A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014168789A1 (en) * 2013-04-10 2014-10-16 Technip France Floating offshore platform with pontoon-coupled extension plates for reduced heave motion

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2314044A (en) * 1996-06-12 1997-12-17 Christopher David Slennett A floating structure with ballast tanks

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3224401A (en) * 1964-04-13 1965-12-21 Shell Oil Co Stabilized floating drilling platform
US3386404A (en) * 1965-08-22 1968-06-04 Motora Seizo Ship's hull adapted for considerably reducing vertical forces caused by waves
US3915108A (en) * 1973-09-24 1975-10-28 Global Marine Inc Apparatus for controlling heave pitch and roll of a floating vessel
GB2008515A (en) * 1977-11-25 1979-06-06 Brown & Root Apparatus to reduce vessel motions
US4505617A (en) * 1979-10-12 1985-03-19 National Research Development Corporation Stabilizing bluff structures against oscillation

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3224401A (en) * 1964-04-13 1965-12-21 Shell Oil Co Stabilized floating drilling platform
US3386404A (en) * 1965-08-22 1968-06-04 Motora Seizo Ship's hull adapted for considerably reducing vertical forces caused by waves
US3915108A (en) * 1973-09-24 1975-10-28 Global Marine Inc Apparatus for controlling heave pitch and roll of a floating vessel
GB2008515A (en) * 1977-11-25 1979-06-06 Brown & Root Apparatus to reduce vessel motions
US4505617A (en) * 1979-10-12 1985-03-19 National Research Development Corporation Stabilizing bluff structures against oscillation

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014168789A1 (en) * 2013-04-10 2014-10-16 Technip France Floating offshore platform with pontoon-coupled extension plates for reduced heave motion
CN105121270A (en) * 2013-04-10 2015-12-02 泰克尼普法国公司 Floating offshore platform with pontoon-coupled extension plates for reduced heave motion
US9302747B2 (en) 2013-04-10 2016-04-05 Technip France Floating offshore platform with pontoon-coupled extension plates for reduced heave motion

Also Published As

Publication number Publication date
GB2257664B (en) 1994-09-28
GB9217049D0 (en) 1992-11-18
FR2670459B1 (en) 1995-07-13
FR2670459A1 (en) 1992-06-19
NO308517B1 (en) 2000-09-25
NO923155D0 (en) 1992-08-12
BR9106221A (en) 1993-03-30
NO923155L (en) 1992-10-12
GB2257664A (en) 1993-01-20

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