EP1260670A1 - Method for dimensioning a drilling riser - Google Patents

Method for dimensioning a drilling riser Download PDF

Info

Publication number
EP1260670A1
EP1260670A1 EP02291245A EP02291245A EP1260670A1 EP 1260670 A1 EP1260670 A1 EP 1260670A1 EP 02291245 A EP02291245 A EP 02291245A EP 02291245 A EP02291245 A EP 02291245A EP 1260670 A1 EP1260670 A1 EP 1260670A1
Authority
EP
European Patent Office
Prior art keywords
tube
riser
tension
assembly
margin
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
EP02291245A
Other languages
German (de)
French (fr)
Other versions
EP1260670B1 (en
Inventor
Jean Guesnon
Christian Gaillard
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.)
IFP Energies Nouvelles IFPEN
Original Assignee
IFP Energies Nouvelles IFPEN
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 IFP Energies Nouvelles IFPEN filed Critical IFP Energies Nouvelles IFPEN
Publication of EP1260670A1 publication Critical patent/EP1260670A1/en
Application granted granted Critical
Publication of EP1260670B1 publication Critical patent/EP1260670B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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

Definitions

  • the present invention relates to the field of offshore drilling, especially using floating support, such as a boat or a semi-submersible platform with dynamic positioning.
  • floating support such as a boat or a semi-submersible platform with dynamic positioning.
  • the head of the well is at the bottom of the sea ("mud-line"), which requires an extension column through the slice of water, a column called “Riser” in the profession.
  • This column which is made up of elements of length between approximately 15 and 30 m, must comply with a specification rigorous loads taking into account the maritime and safety conditions of drilling.
  • the riser is the key element of drilling in great depths of water and must be studied with the greatest care.
  • the architecture of such a riser depends a number of parameters related to operational conditions and environment, such as water depth, maximum density of the drilling mud, the diameter of the peripheral lines (kill-line, choke-line) and their working pressure, sea conditions and current profiles, the offset of the floating support (with dynamic positioning or not).
  • the conditions are different in drilling mode (riser connected to the wellhead and attached to the tensioning means) and in disconnected mode (riser suspended under the floating support, suspended from the drilling table without the intermediary of means tensioning).
  • the means of flotation taken can be modified account in step a) when the voltage margin in disconnected mode is far from said determined value, so as to approach the value of said margin.
  • the thickness of the main tube can be varied when the constraints of Von-Mises calculated in step c) do not respect said determined criterion. We can thus optimize the architecture of the entire riser or riser.
  • the criterion may consist in imposing that the constraints of Von-Mises are less than 2/3 of the elastic limit of the steel of the main tube.
  • the thickness of the tube can be increased when said constraints are greater than about 2/3 of the elastic limit, and we can decrease the thickness of the tube when said stresses are less than about 2/3 of the elastic limit.
  • a loss thickness of the main tube and a loss of buoyancy of the means of waterline may correspond to the manufacturing tolerance and / or corrosion. Loss of buoyancy may be due to absorption of water over time.
  • the tensioning margin in disconnected mode can be at least equal to 20 t.
  • reference 1 designates the entire riser or "riser” drilling.
  • the schematic subsea wellhead is referenced 2.
  • the riser is linked to the well head 2 by a flexible joint 3 fixed above the upper control unit 4 comprising, inter alia, a connector which allows the disconnection of the riser from the shutter block.
  • the part lower 5 of the riser is devoid of buoyancy elements unlike the upper part 6.
  • the top of the riser is connected to the floating support 7 by via tensioning winches (not shown).
  • Figure 2 shows a cross section of a riser element mainly consisting of a main and central tube 8, of tubular lines auxiliaries (kill-line, choke-line, boosting line) 9, buoyancy elements 10, usually in the form of two syntactic foam half shells or equivalent material.
  • Figure 3 illustrates a riser element comprising a pair of upper 11 and lower 12 connectors whose functions are to connect the main tubes together, but also to connect the auxiliary lines.
  • Reference 13 designates a half buoyancy element shell.
  • T true T effective + P i S i - P e S e where P i , P e respectively internal and external pressure of the tube S i , S e respectively internal and external section
  • T riser effective ( z ) T top - ⁇ top z ( W riser + W mud )
  • T riser effective T MP effective + ⁇ T AL effective
  • T connector true T MP effective + ( P i - P e ) * S seal where S seal is the connector sealing section.
  • T MP / effective is normally maximum at the top of the riser. ( P i - P e ) * S seal is maximum at the foot of riser. Thus, there is a depth for which the T connector / true tension in the connectors is maximum (around 1500 - 2000m), depending on the mud density considered.
  • the tension at the head of the riser must always remain positive when the drill stand is subject to heaving.
  • the head tension is the difference between the weight apparent riser and the tension amplified by the pounding of the support floating. This criterion therefore requires that the weight of the suspended riser is greater at the maximum amplitude of the voltage variation at any point of the riser. We can take, for example 20 t of safety margin.
  • the amplified voltage of the riser according to the heaving results from a conventional dynamic calculation.
  • each section of the riser is optimized to meet the criteria of the mode drilling (connected) while the compensation (see formula below) is adjusted to avoid any "stress relieving" (negative head tension or less than a safety margin) in disconnected mode.
  • Compensation is an important ratio which makes it possible to fix the diameter floats.
  • the compensation In a first design phase, the compensation must be the as high as possible so that the head tension is minimal. However, the compensation must be adjusted to meet the criteria for disconnected mode. A compromise must be found to meet the criteria.
  • 100% compensation means that the apparent weight of the riser sucks.
  • a dimensioning preliminary thickness and diameter of floats
  • iterations on the global compensation and the thickness of the main tube of each section can be conducted from the way below.
  • the criterion in disconnected mode must be checked (see above dimensioning principles). Security in the face of “stress relieving” must be determined by considering decennial sea conditions or centennial. If the safety margin is negative (i.e. the riser is subject to a risk of dynamic buckling), the compensation must be decreased. If the safety margin is too large, compensation may be increased.
  • the compensation has been adjusted in disconnected mode, you must check the criteria of the connected mode (see above the principles of sizing).
  • the Von-Mises criteria must be checked for each riser section. If these constraints exceed 2/3 of the elastic limit, the thickness of the main tube should be increased by 1/16 of an inch. Conversely, if these constraints are lower than the elastic limit, the thickness of the main tube can be reduced by 1/16 ". After each modification of the thickness of a section, the safety margin facing the "Stress relieving" should be checked in order to re-adjust the compensation.
  • the last step of the design goes through a dynamic calculation. These calculations must take into account the movements of the drilling rig (heaving, offset), current profile, sea conditions to assess the axial and bending stresses at any point of the riser, as well as the angle in foot.
  • This last step can be carried out using element software such as Deeplines TM (IFP) (Fully coupled dynamic analysis of rigid lines-J.M. Heurtier, F. Biolley (IFP); C. Berhault (Principia) -p 246-252, proceedings of ISOPE 98 - Canada-Montreal).
  • IFP Deeplines TM
  • This first architecture makes it possible to calculate in disconnected mode DM the safety margin M representing the margin of voltage between the amplified voltage Ta of the riser taking into account the heaving of the support and the apparent weight of the riser W. If this margin is negative, or judged insufficient, we loop through line 21 by decreasing the value of the compensation C. If the margin is considered too large, we loop through the line 22 by increasing the compensation C. We can take, for example, a margin of about 20 tonnes.
  • Block 27 shows schematically the obtaining of the final architecture, responding to the specifications and standards in force.
  • All of the steps 28 can be compared to verifications in calculating the tension at the head of the TT riser taking into account the thickness nominal EN of the tube, without corrosion and considering a loss of buoyancy 3%. From TT, we check (block 29) if the connectors are compatible with this tension, and if the tensioning means of the floating support are enough.
  • the architecture of the riser obtained is dynamically verified using DeepLines TM software (IFP), or equivalent.
  • IFP DeepLines TM software

Landscapes

  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • Mechanical Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Earth Drilling (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Drilling And Exploitation, And Mining Machines And Methods (AREA)
  • Diaphragms For Electromechanical Transducers (AREA)

Abstract

A design is chosen from a loads book and its apparent weight calculated. If the tension loads on the disconnected assembly are near a preset safety limit, the Von-Mises constraints are calculated for each tube section when it is connected. If these are near the tube material's elastic limit, each component is checked for the maximum tension, fatigue and dynamic loads imposed on the assembly Sizing a riser (1) connecting a seabed wellhead (2) to a floating support (7) via a main tube (8) comprises: (a) selecting the complete architecture of the riser using a book of loads, in particular to determine the thickness of the main tube and the type of float, and calculating the apparent weight of the assembly; (b) determining a safety margin on the tension of the assembly when it is disconnected from the wellhead, taking into account the apparent weight and the amplified tension at the head by movements of the floating support from which the assembly is suspended; (c) calculating the Von-Mises constraints in each section of the tube when it is connected to the wellhead, when the when the margin is near a preset value; and (d) when the constraints are near a predetermined criterion relative to the elastic limit of the tube material, obtaining the riser tube architecture and checking each component for compatibility with the maximum tension, fatigue and dynamic loads imposed on the assembly. The floatation device is modified until the margin of tension in the disconnected state is extended to the preset value, by varying the number of floats, the division of floats, the float diameter, or the density of the float material. The tube thickness is varied until the Van-Mises constraints approach the preset criteria of less than 2/3 of the elastic limit of the main tube steel. The calculations allow for a loss of thickness of the main tube and a loss of buoyancy of the floats. The margin is at least equal to 20 tonnes.

Description

La présente invention concerne le domaine du forage en mer, notamment à l'aide de support flottant, tel un bateau ou une plate-forme semi-submersible à positionnement dynamique. Dans ce mode d'exploitation, la tête du puits se trouve au niveau du fond de la mer (« mud-line »), ce qui impose une colonne de prolongation à travers la tranche d'eau, colonne dénommée « riser » dans la profession. Cette colonne qui est constituée d'éléments de longueur comprise entre environ 15 et 30 m, doit respecter un cahier des charges rigoureux compte tenu des conditions maritimes et de sécurité de forage.The present invention relates to the field of offshore drilling, especially using floating support, such as a boat or a semi-submersible platform with dynamic positioning. In this operating mode, the head of the well is at the bottom of the sea ("mud-line"), which requires an extension column through the slice of water, a column called "Riser" in the profession. This column which is made up of elements of length between approximately 15 and 30 m, must comply with a specification rigorous loads taking into account the maritime and safety conditions of drilling.

Aussi, le riser est l'élément clé du forage par grande profondeur d'eau et doit être étudié avec le plus grand soin. L'architecture d'un tel riser dépend d'un certain nombre de paramètres liés aux conditions opérationnelles et d'environnement, telles que la profondeur d'eau, la densité maximale de la boue de forage, le diamètre des lignes périphériques (kill-line, choke-line) et leur pression de service, les états de mer et les profils de courant, le déport du support flottant (avec positionnement dynamique ou non). Les conditions sont différentes en mode de forage (riser connecté à la tête de puits et accroché aux moyens de tensionnement) et en mode déconnecté (riser suspendu sous le support flottant, suspendu à la table de forage sans l'intermédiaire des moyens de tensionnement).Also, the riser is the key element of drilling in great depths of water and must be studied with the greatest care. The architecture of such a riser depends a number of parameters related to operational conditions and environment, such as water depth, maximum density of the drilling mud, the diameter of the peripheral lines (kill-line, choke-line) and their working pressure, sea conditions and current profiles, the offset of the floating support (with dynamic positioning or not). The conditions are different in drilling mode (riser connected to the wellhead and attached to the tensioning means) and in disconnected mode (riser suspended under the floating support, suspended from the drilling table without the intermediary of means tensioning).

Tous ces paramètres doivent être pris en considération pour dimensionner chaque composant du système "riser": le tube principal, les lignes périphériques, les connecteurs, les flotteurs (flottabilité et répartition), le système de tensionnement..., tout en respectant les règles normales de sécurité et les procédures habituelles des entrepreneurs de forage.All these parameters must be taken into account for dimension each component of the riser system: the main tube, the peripheral lines, connectors, floats (buoyancy and distribution), the tensioning system ..., while respecting the normal rules of safety and usual procedures of drilling contractors.

Ainsi, la présente invention concerne une méthode pour dimensionner un ensemble prolongateur pour le forage en mer reliant une tête de puits sous-marine à un support flottant comprenant un tube principal, dans laquelle on effectue les étapes suivantes:

  • on choisit une architecture complète de l'ensemble prolongateur à partir d'un cahier des charges, notamment en se fixant l'épaisseur du tube principal et des moyens de flottaison, et on calcule le poids apparent de cet ensemble,
  • on détermine la marge de tension en tête dudit ensemble, en mode déconnecté de la tête du puits, compte tenu du poids apparent et de la tension amplifiée en tête par les mouvements du support flottant auquel est suspendu ledit ensemble,
  • dans le cas où la marge de tension correspond à une valeur proche d'une valeur déterminée, on calcule les contraintes de Von-Mises dans toutes les sections du tube, en mode connecté à la tête du puits,
  • dans le cas où lesdites contraintes sont proche d'un critère déterminé en relation avec la limite élastique du matériau du tube: on vérifie par calcul la charge sur chaque composant de l'ensemble prolongateur, ainsi que sa fatigue en dynamique.
Thus, the present invention relates to a method for dimensioning an extension assembly for drilling at sea connecting an underwater wellhead to a floating support comprising a main tube, in which the following steps are carried out:
  • a complete architecture of the extension assembly is chosen from a specification, in particular by setting the thickness of the main tube and the flotation means, and the apparent weight of this assembly is calculated,
  • the tension margin at the head of said assembly is determined, in disconnected mode from the well head, taking into account the apparent weight and the voltage amplified at the head by the movements of the floating support to which said assembly is suspended,
  • in the case where the tension margin corresponds to a value close to a determined value, the stresses of Von-Mises are calculated in all the sections of the tube, in mode connected to the head of the well,
  • in the case where said stresses are close to a criterion determined in relation to the elastic limit of the material of the tube: the load on each component of the extension assembly is checked by calculation, as well as its fatigue in dynamics.

Selon la méthode, on peut modifier les moyens de flottaison pris en compte dans l'étape a) lorsque la marge de tension en mode déconnecté est éloignée de ladite valeur déterminée, de façon à approcher la valeur de ladite marge.Depending on the method, the means of flotation taken can be modified account in step a) when the voltage margin in disconnected mode is far from said determined value, so as to approach the value of said margin.

On peut modifier les moyens de flottaison en faisant varier au moins l'un des paramètres suivants: le nombre de flotteurs, le diamètre des flotteurs, la masse volumique du matériau des flotteurs.You can modify the flotation means by varying at least one of the following parameters: the number of floats, the diameter of the floats, the density of the float material.

On peut faire varier l'épaisseur du tube principal lorsque les contraintes de Von-Mises calculées à l'étape c) ne respectent pas ledit critère déterminé. On peut ainsi optimiser l'architeture de l'ensemble de la colonne montante ou riser.The thickness of the main tube can be varied when the constraints of Von-Mises calculated in step c) do not respect said determined criterion. We can thus optimize the architecture of the entire riser or riser.

Le critère peut consister à imposer à ce que les contraintes de Von-Mises soient inférieures à 2/3 de la limite élastique de l'acier du tube principal.The criterion may consist in imposing that the constraints of Von-Mises are less than 2/3 of the elastic limit of the steel of the main tube.

On peut augmenter l'épaisseur du tube lorsque lesdites contraintes sont supérieures à environ 2/3 de la limite élastique, et on peut diminuer l'épaisseur du tube lorsque lesdites contraintes sont inférieures à environ 2/3 de la limite élastique. The thickness of the tube can be increased when said constraints are greater than about 2/3 of the elastic limit, and we can decrease the thickness of the tube when said stresses are less than about 2/3 of the elastic limit.

On peut effectuer les étapes a) et b) en prenant en compte une perte d'épaisseur du tube principal et une perte de flottabilité des moyens de flottaison. La perte d'épaisseur peut correspondre à la tolérance de fabrication et/ou une corrosion. La perte de flottabilité peut être due à une absorption d'eau au cours du temps.We can perform steps a) and b) taking into account a loss thickness of the main tube and a loss of buoyancy of the means of waterline. The loss of thickness may correspond to the manufacturing tolerance and / or corrosion. Loss of buoyancy may be due to absorption of water over time.

La marge de tensionnement en mode déconnecté peut être au moins égale à 20 t.The tensioning margin in disconnected mode can be at least equal to 20 t.

Sur la base de son expertise, la demanderesse a donc développé une méthodologie pour optimiser le dimensionnement des risers de forage en fonction des conditions d'utilisation. Un outil de calcul, par exemple sous la forme d'une feuille Excel, a été développé respectant la méthodologie proposée.Based on its expertise, the plaintiff has therefore developed a methodology to optimize the dimensioning of drilling risers in depending on the conditions of use. A calculation tool, for example under the form of an Excel sheet, has been developed respecting the proposed methodology.

La présente invention sera mieux comprise et ses avantages apparaítront plus clairement à la lecture de la description suivante, illustrée par les figures ci-après annexées, parmi lesquelles :

  • la figure 1 décrit une installation de forage offshore,
  • la figure 2 montre une coupe transversale d'un riser,
  • la figure 3 montre une élément de riser équipé de moyens de flottaison,
  • la figure 4 illustre le principe de la méthodologie selon l'invention.
The present invention will be better understood and its advantages will appear more clearly on reading the following description, illustrated by the appended figures below, among which:
  • FIG. 1 describes an offshore drilling installation,
  • FIG. 2 shows a cross section of a riser,
  • FIG. 3 shows a riser element fitted with flotation means,
  • FIG. 4 illustrates the principle of the methodology according to the invention.

Sur la figure 1, la référence 1 désigne l'ensemble de la colonne montante ou « riser » de forage. La tête de puits sous-marine schématique est référencée 2. Le riser est liée à la tête de puits 2 par un joint flexible 3 fixée au dessus du bloc de commande supérieur 4 comportant, entre autre, un connecteur qui permet la déconnexion du riser du bloc des obturateurs. On note que la partie basse 5 du riser est dépourvue d'éléments de flottabilité contrairement à la partie supérieure 6. Le sommet du riser est relié au support flottant 7 par l'intermédiaire de treuils de tensionnement (non représentés).In Figure 1, reference 1 designates the entire riser or "riser" drilling. The schematic subsea wellhead is referenced 2. The riser is linked to the well head 2 by a flexible joint 3 fixed above the upper control unit 4 comprising, inter alia, a connector which allows the disconnection of the riser from the shutter block. We note that the part lower 5 of the riser is devoid of buoyancy elements unlike the upper part 6. The top of the riser is connected to the floating support 7 by via tensioning winches (not shown).

La figure 2 représente une coupe transversale d'un élément de riser constitué principalement d'un tube principal et central 8, de lignes tubulaires auxiliaires (kill-line, choke-line, boosting line) 9, d'éléments de flottabilité 10, généralement sous la forme de deux demies coquilles en mousse syntactique ou matériau équivalent.Figure 2 shows a cross section of a riser element mainly consisting of a main and central tube 8, of tubular lines auxiliaries (kill-line, choke-line, boosting line) 9, buoyancy elements 10, usually in the form of two syntactic foam half shells or equivalent material.

La figure 3 illustre un élément de riser comprenant une paire de connecteurs supérieur 11 et inférieur 12 dont les fonctions sont de connecter les tubes principaux entre eux, mais aussi de connecter les lignes auxiliaires. La référence 13 désigne une demie coquille d'élément de flottabilité.Figure 3 illustrates a riser element comprising a pair of upper 11 and lower 12 connectors whose functions are to connect the main tubes together, but also to connect the auxiliary lines. Reference 13 designates a half buoyancy element shell.

Mécanique des risersRisers mechanics

La tension TTop en tête du riser est un paramètre important qu'il est nécessaire de connaítre avec précision pour choisir le système de tensionnement adapté. Cette tension est composée de trois termes : TTop = Wriser + Wmud + Tbottom    où Wriser : poids apparent du riser (dans l'eau de mer)
   Wmud : poids apparent de la boue
   Tbottom : tension résiduelle en pied de riserThe tension T Top at the head of the riser is an important parameter that it is necessary to know precisely to choose the appropriate tensioning system. This tension is made up of three terms: T top = W riser + W mud + T bottom where W riser : apparent weight of riser (in seawater)
W mud : apparent weight of the mud
T bottom : residual tension at the foot of riser

Ces termes sont calculés séparément en considérant les caractéristiques du riser. Par exemple: ◆ Wriser =WMP + WAL +Wmisc + ΔBM    où WMP : poids apparent du tube principal (tube central de 21" et connecteurs)
   WAL : poids apparent des lignes périphériques ;
   Wmisc : poids apparent des autres composants (joint télescopique, joint flexible, joint de terminaison, etc)
   ΔBM : poids apparent des flotteurs (de signe négatif) ◆ Wmud = π4 [ID 2 MP + ΣID2 AL ]*(ρmud - ρsw )*Lriser    où ID 2 MP : diamètre intérieur du tube principal ;
   ID 2 AP : diamètre intérieur des lignes périphériques ;
   ρ sw : densité de l'eau de mer ;
   Lriser : longueur totale du riser.

  • La tension résiduelle en pied de riser Tbottom doit être maintenue positive pour respecter un angle en pied dans les limites fixées par la norme API 16Q (angle moyen de 2° en statique). Pour la plupart des cas, cette tension est de l'ordre de 100 t.
These terms are calculated separately considering the characteristics of the riser. For example: ◆ W riser = W MP + W AL + W misc + Δ BM where W MP : apparent weight of the main tube (21 "central tube and connectors)
W AL : apparent weight of the peripheral lines;
W misc : apparent weight of the other components (telescopic joint, flexible joint, termination joint, etc.)
Δ BM : apparent weight of the floats (of negative sign) ◆ W mud = π 4 [ ID 2 MP + ΣID 2 AL ] * ( ρ mud - ρ sw ) * L riser where ID 2 MP : internal diameter of the main tube;
ID 2 AP : inner diameter of the peripheral lines;
ρ sw : density of sea water;
L riser : total length of the riser.
  • The residual tension at the bottom of riser T bottom must be kept positive to respect a bottom angle within the limits set by API 16Q standard (mean angle of 2 ° in static). In most cases, this tension is around 100 t.

Tension effective et tension vraie :Effective voltage and true voltage:

Il existe une différence fondamentale entre tension effective et tension vraie. Généralement, la tension vraie Ttrue gouverne les déformations et les contraintes dans le tube et les connecteurs. Teffective est la tension qui régit la stabilité de la liaison et gouverne la déformée et la flexion dans le riser. La relation entre ces deux tensions est la suivante: Ttrue = Teffective + PiSi - PeSe    où Pi, Pe respectivement pression interne et externe du tube
   Si , Se respectivement section interne et externeThere is a fundamental difference between effective voltage and true voltage. Generally, the true tension T true governs the deformations and the stresses in the tube and the connectors. T effective is the tension which governs the stability of the connection and governs the deformation and bending in the riser. The relationship between these two tensions is as follows: T true = T effective + P i S i - P e S e where P i , P e respectively internal and external pressure of the tube
S i , S e respectively internal and external section

La tension effective peut être calculée en tout point du riser: Triser effective (z) = TTop - Σtop z (Wriser + Wmud ) The effective tension can be calculated at any point of the riser: T riser effective ( z ) = T top - Σ top z ( W riser + W mud )

L'équation donnant la déformée (y) du riser peut être dérivée de la façon suivante: EI ∂4y∂z4 -∂∂z ( T eff ∂y∂z ) = q(z)    où E : module d'Young du matériau
   I : moment d'inertie du riser
   q(z): chargement latéral dû au courantThe equation giving the deformation (y) of the riser can be derived as follows: EI ∂ 4 there ∂z 4 - ∂ ∂z ( T eff ∂y ∂z ) = q ( z ) where E : Young's modulus of the material
I : moment of inertia of the riser
q ( z ): lateral loading due to current

La tension effective doit toujours est positive en tout point du riser pour éviter les phénomènes d'instabilité, par exemple le flambage. Triser effective = TMP effective + ΣTAL effective The effective tension must always be positive at any point of the riser to avoid the phenomena of instability, for example buckling. T riser effective = T MP effective + Σ T AL effective

Cette équation permet de coupler les tensions dans les différents tubes (tube principal et conduites périphériques) et ainsi de recalculer tous les efforts axiaux dans chaque composant du riser.This equation makes it possible to couple the tensions in the various tubes (main tube and peripheral pipes) and thus recalculate all the axial forces in each component of the riser.

Comportement des lignes périphériques sous pression : Behavior of peripheral lines under pressure :

Ces tubes de petit diamètre sont fixés individuellement le long de chaque élément de riser. Leurs embouts possèdent les joints d'étanchéité nécessaires, mais ne comportent pas d'organes permettant de transmettre des efforts d'un tube à un autre: les tubes simplement flottant s'emboítent les uns dans les autres. Il s'ensuit, en première approximation, qu'aucune tension réelle élevée ne s'exerce sur ces tubes (T AL / actual ≈ -Pi (Se - Si ) si l'on suppose que le diamètre d'étanchéité est égal au diamètre extérieur du tube). Ces tubes véhiculent des fluides sous forte pression de service et donc T AL / effective = -(Pi - Pe )S AL / seal, est fortement négative si le tube est sous pression interne élevée. Ainsi, les tubes vont avoir tendance à flamber et des colliers de maintien convenablement espacés sont indispensables pour contrecarrer cette tendance.These small diameter tubes are attached individually along each riser element. Their tips have the necessary seals, but do not include members for transmitting forces from one tube to another: the simply floating tubes fit into each other. It follows, as a first approximation, that no real high tension is exerted on these tubes ( T AL / actual ≈ - P i ( S e - S i ) if we assume that the sealing diameter is equal to the outside diameter of the tube). These tubes convey fluids under high operating pressure and therefore T AL / effective = - ( P i - P e ) S AL / seal , is strongly negative if the tube is under high internal pressure. Thus, the tubes will tend to buckle and appropriately spaced retaining collars are essential to counter this tendency.

Influence de la pression dans les lignes périphériques sur le tube principal : Influence of the pressure in the peripheral lines on the main tube :

Un autre effet important induit par la mise en pression des lignes périphériques est l'augmentation de la traction dans le tube principal. En effet, la tension effective totale du riser (T riser / effective) est inchangée lorsque les lignes sont sous pression [voir équation (E5)] car le poids de la boue et du riser restent constant. La tension effective des lignes périphériques (T AL / effective) diminue (valeur négative) du fait de la pressurisation. La tension effective du tube principal augmente (E7). Ainsi, compte tenu de l'équation (E5), la tension vraie dans le tube principale augmente de la même façon: δ〈TMP true〉 + Σδ(TAL effective ) = 0 Another important effect induced by the pressure of the peripheral lines is the increase in traction in the main tube. Indeed, the total effective tension of the riser ( T riser / effective ) is unchanged when the lines are under pressure [see equation (E5)] because the weight of the mud and of the riser remain constant. The effective tension of the peripheral lines ( T AL / effective ) decreases (negative value) due to the pressurization. The effective tension of the main tube increases (E7). Thus, given equation (E5), the true tension in the main tube increases in the same way: δ <T MP true 〉 + Σδ ( T AL effective ) = 0

Il s'ensuit en pratique qu'une traction additionnelle s'exerce sur le tube principal lorsque les lignes périphériques sont sous pression. De l'ordre de 250 t par ligne périphérique de 15,000 psi de pression de service (103,5 Mpa) et 4½" (114,3 mm) de diamètre intérieur.It follows in practice that an additional traction is exerted on the tube main when the peripheral lines are under pressure. Of the order of 250 t per peripheral line of 15,000 psi of working pressure (103.5 Mpa) and 4½ "(114.3 mm) inside diameter.

Efforts dans les connecteurs :Efforts in connectors:

Du fait de la composition du riser, tous les efforts transitent par les connecteurs. Ces efforts sont supérieurs à ceux du tube principal et peuvent être calculés ainsi: Tconnector true = TMP effective + (Pi - Pe )*Sseal    où Sseal est la section d'étanchéité du connecteur.Due to the composition of the riser, all efforts pass through the connectors. These forces are greater than those of the main tube and can be calculated as follows: T connector true = T MP effective + ( P i - P e ) * S seal where S seal is the connector sealing section.

T MP / effective est normalement maximale en tête du riser. (Pi - Pe )*Sseal est maximale en pied de riser. Ainsi, il existe une profondeur pour laquelle la tension T connector / true dans les connecteurs est maximale (vers 1500 - 2000m), suivant la densité de boue considérée. T MP / effective is normally maximum at the top of the riser. ( P i - P e ) * S seal is maximum at the foot of riser. Thus, there is a depth for which the T connector / true tension in the connectors is maximum (around 1500 - 2000m), depending on the mud density considered.

Principes de design des risers de forageDesign principles of drilling risers

Le riser de forage doit être dimensionné suivant les recommandations données par la norme API 16Q:

  • les contraintes de Von-Mises sont inférieures à 2/3 de la limite élastique,
  • l'angle moyen en pied de riser inférieur à 2° en statique.
The drilling riser must be sized according to the recommendations given by API 16Q standard:
  • the Von-Mises stresses are less than 2/3 of the elastic limit,
  • the average angle at the base of riser less than 2 ° in static.

Aucune autre spécification quantitative n'est indiquée dans cette recommandation. Pour considérer la corrosion, la fatigue, la pression dans les lignes périphériques, etc...pour le dimensionnement des risers de forage, il est proposé selon l'invention une méthodologie pratique pour les risers de forage à la fois en mode de forage et en mode déconnecté (stand-by).No other quantitative specification is indicated in this recommendation. To consider corrosion, fatigue, pressure in the peripheral lines, etc. for the dimensioning of drilling risers, it is proposed according to the invention a practical methodology for drilling risers at both in drilling mode and in offline mode (stand-by).

◆ Mode forage ◆ Drilling mode

C'est le mode le plus courant. Les critères adoptés pour le mode de forage sont présentés ci-après.This is the most common mode. The criteria adopted for the mode of drilling are shown below.

Les contraintes de Von-Mises doivent être inférieures à 2/3 de la limite élastique en considérant les paramètres suivant:

  • Le riser est connecté à l'appareil de forage par un joint télescopique et un système de tensionnement.
  • Le riser est rempli par la boue de densité maximale.
  • Les lignes périphériques sont sous pression.
  • L'épaisseur du tube principal est diminuée de 5%, sur toute sa longueur, pour prendre en compte les tolérances des tubes.
  • L'épaisseur du tube principal est diminuée de 2 mm pour prendre en compte la corrosion.
  • Les flotteurs ont une perte de flottabilité de 3% due à la pénétration d'eau de mer.
The Von-Mises stresses must be less than 2/3 of the elastic limit considering the following parameters:
  • The riser is connected to the drilling rig by a telescopic joint and a tensioning system.
  • The riser is filled with mud of maximum density.
  • The peripheral lines are under pressure.
  • The thickness of the main tube is reduced by 5%, over its entire length, to take into account the tolerances of the tubes.
  • The thickness of the main tube is reduced by 2 mm to take corrosion into account.
  • The floats have a loss of buoyancy of 3% due to the penetration of sea water.

◆ Mode déconnecté: stand-by ◆ Disconnected mode: stand-by

Dans cette situation critique, pour éviter la ruine de la structure, la tension en tête du riser doit rester toujours positive quand le support de forage est soumis à du pilonnement. La tension en tête est la différence entre le poids apparent du riser et la tension amplifiée par le pilonnement du support flottant. Ce critère nécessite donc que le poids du riser suspendu soit supérieur à l'amplitude maximale de la variation de la tension en tout point du riser. On peut prendre, par exemple 20 t de marge de sécurité. La tension amplifiée du riser en fonction du pilonnement résulte d'un calcul dynamique conventionnel.In this critical situation, to avoid ruining the structure, the tension at the head of the riser must always remain positive when the drill stand is subject to heaving. The head tension is the difference between the weight apparent riser and the tension amplified by the pounding of the support floating. This criterion therefore requires that the weight of the suspended riser is greater at the maximum amplitude of the voltage variation at any point of the riser. We can take, for example 20 t of safety margin. The amplified voltage of the riser according to the heaving results from a conventional dynamic calculation.

Ainsi, dans ce mode, les calculs doivent prendre en compte les hypothèses suivantes:

  • Le riser est déconnecté de la tête de puits.
  • Le tube principal et les lignes périphériques sont remplis d'eau.
  • Les lignes périphériques sont à la pression hydrostatique.
  • L'épaisseur du tube principal est diminuée de 5%, sur toute sa longueur, pour prendre en compte les tolérances des tubes.
  • L'épaisseur du tube principal est diminuée de 2 mm pour prendre en compte la corrosion.
  • Les flotteurs ont une perte de flottabilité de 3% due à la présence d'eau de mer.
Thus, in this mode, the calculations must take into account the following assumptions:
  • The riser is disconnected from the wellhead.
  • The main tube and the peripheral lines are filled with water.
  • The peripheral lines are at hydrostatic pressure.
  • The thickness of the main tube is reduced by 5%, over its entire length, to take into account the tolerances of the tubes.
  • The thickness of the main tube is reduced by 2 mm to take corrosion into account.
  • The floats have a loss of buoyancy of 3% due to the presence of sea water.

Pendant la phase de dimensionnement, les calculs se font de manière itérative entre ces deux modes afin d'optimiser l'architecture. L'épaisseur de chaque section du riser est optimisée pour répondre aux critères du mode forage (connecté) alors que la compensation (voir formule ci-dessous) est ajustée pour éviter tout « détensionnement » (tension en tête négative ou inférieure à un marge de sécurité) en mode déconnecté.During the dimensioning phase, the calculations are made so iterative between these two modes in order to optimize the architecture. The thickness of each section of the riser is optimized to meet the criteria of the mode drilling (connected) while the compensation (see formula below) is adjusted to avoid any "stress relieving" (negative head tension or less than a safety margin) in disconnected mode.

La compensation (C) est définie de la manière suivante: C% = Δ BM Σ(WMP +WAL +Wmisc ) The compensation (C) is defined as follows: VS % = Δ BM Σ ( W MP + W AL + W misc )

La compensation est un ratio important qui permet de fixer le diamètre des flotteurs. Dans une première phase de design, la compensation doit être la plus élevée possible pour que la tension en tête soit minimale. Cependant, la compensation doit être ajustée pour répondre aux critères du mode déconnecté. Un compromis doit être trouvé pour respecter les critères.Compensation is an important ratio which makes it possible to fix the diameter floats. In a first design phase, the compensation must be the as high as possible so that the head tension is minimal. However, the compensation must be adjusted to meet the criteria for disconnected mode. A compromise must be found to meet the criteria.

Remarque: une compensation de 100% signifie que le poids apparent du riser est nul.Note: 100% compensation means that the apparent weight of the riser sucks.

Comme nous avons pu le voir au paragraphe précédent, le dimensionnement du riser dépend de nombreux paramètres.

  • Les conditions de l'environnement, ainsi que la profondeur d'eau, sont fixées par la localisation du forage.
  • La densité maximale de la boue est imposée par les prévisions des pressions attendues, notamment du réservoir.
  • Les caractéristiques des lignes périphériques (diamètre, pression de service) sont déterminées à partir de la pression de service des obturateurs de sécurité (BOP) (10,000 psi ou 15,000 psi).
  • Le diamètre du tube principal du riser (souvent 21") est dicté par le programme de forage.
  • Les caractéristiques du matériau des flotteurs définissent les différentes sections du riser: une section pour une densité de mousse (souvent tous les 500 à 600 m).
As we could see in the previous paragraph, the dimensioning of the riser depends on many parameters.
  • The environmental conditions, as well as the water depth, are determined by the location of the borehole.
  • The maximum density of the mud is imposed by the forecasts of the expected pressures, in particular of the reservoir.
  • The characteristics of the peripheral lines (diameter, operating pressure) are determined from the operating pressure of the safety shutters (BOP) (10,000 psi or 15,000 psi).
  • The diameter of the riser's main tube (often 21 ") is dictated by the drilling program.
  • The characteristics of the float material define the different sections of the riser: a section for a density of foam (often every 500 to 600 m).

Avec ces éléments plus ou moins imposés, un dimensionnement préliminaire (épaisseur et diamètre des flotteurs) peut être trouvé. Pour optimiser ce dimensionnement, des itérations sur la compensation globale et l'épaisseur du tube principal de chaque section peuvent être menées de la façon ci-après.With these more or less imposed elements, a dimensioning preliminary (thickness and diameter of floats) can be found. For optimize this dimensioning, iterations on the global compensation and the thickness of the main tube of each section can be conducted from the way below.

Tout d'abord, le critère en mode déconnecté doit être vérifié (voir supra les principes de dimensionnement). La sécurité face au « détensionnement » doit être déterminée en considérant des conditions de mer décennales ou centennales. Si la marge de sécurité est négative (c'est à dire que le riser est soumis à un risque de flambage dynamique), la compensation doit être diminuée. Si la marge de sécurité est trop importante, la compensation peut être augmentée.First of all, the criterion in disconnected mode must be checked (see above dimensioning principles). Security in the face of “stress relieving” must be determined by considering decennial sea conditions or centennial. If the safety margin is negative (i.e. the riser is subject to a risk of dynamic buckling), the compensation must be decreased. If the safety margin is too large, compensation may be increased.

Une fois que la compensation a été ajustée en mode déconnecté, il faut vérifier les critères du mode connecté (voir supra les principes de dimensionnement). Les critères de Von-Mises doivent être vérifiés pour chaque section de riser. Si ces contraintes dépassent les 2/3 de la limite élastique, l'épaisseur du tube principal doit être augmentée de 1/16 de pouce. Inversement, si ces contraintes sont inférieures à la limite élastique, l'épaisseur du tube principal peut-être diminuée de 1/16". Après chaque modification de l'épaisseur d'une section, la marge de sécurité face au « détensionnement » doit être vérifiée afin d'ajuster à nouveau la compensation.Once the compensation has been adjusted in disconnected mode, you must check the criteria of the connected mode (see above the principles of sizing). The Von-Mises criteria must be checked for each riser section. If these constraints exceed 2/3 of the elastic limit, the thickness of the main tube should be increased by 1/16 of an inch. Conversely, if these constraints are lower than the elastic limit, the thickness of the main tube can be reduced by 1/16 ". After each modification of the thickness of a section, the safety margin facing the "Stress relieving" should be checked in order to re-adjust the compensation.

Toutes ces itérations doivent conduire au design final du système riser. La tension maximale en tête peut ainsi être déduite en considérant une épaisseur nominale du tube principal, sans corrosion, et avec une perte de poussée des flotteurs de 3%. Cette tension en tête doit être compatible avec la capacité des tensionneurs calculée suivant l'API 16Q (section 3.3.2). De plus la classe des connecteurs doit être aussi en accord avec les efforts maximaux calculés avec la pression dans les lignes périphériques (voir équation E9).All these iterations must lead to the final design of the riser system. The maximum head tension can thus be deduced by considering a nominal thickness of the main tube, without corrosion, and with a loss of float thrust of 3%. This head tension must be compatible with the tensor capacity calculated according to API 16Q (section 3.3.2). Furthermore the connector class must also be in accordance with the maximum forces calculated with the pressure in the peripheral lines (see equation E9).

Enfin, la dernière étape du design passe par un calcul dynamique. Ces calculs devront prendre en compte les déplacements de l'engin de forage (pilonnement, offset), le profil de courant, les conditions de mer pour évaluer les contraintes axiales et de flexion en tout point du riser, ainsi que l'angle en pied. Cette dernière étape pourra être réalisée à l'aide d'un logiciel d'éléments finis comme par exemple Deeplines ™ (IFP)(Fully coupled dynamic analysis of rigid lines-J.M. Heurtier, F. Biolley (IFP); C.Berhault (Principia)-p 246-252, proceedings of ISOPE 98 - Canada-Montreal).Finally, the last step of the design goes through a dynamic calculation. These calculations must take into account the movements of the drilling rig (heaving, offset), current profile, sea conditions to assess the axial and bending stresses at any point of the riser, as well as the angle in foot. This last step can be carried out using element software such as Deeplines ™ (IFP) (Fully coupled dynamic analysis of rigid lines-J.M. Heurtier, F. Biolley (IFP); C. Berhault (Principia) -p 246-252, proceedings of ISOPE 98 - Canada-Montreal).

Cette méthodologie peut être schématisée à l'aide de l'organigramme selon la figure 4.This methodology can be schematized using the flowchart according to figure 4.

L'ensemble des blocs 20 schématise les entrées de données de calculs :

  • caractéristiques du tube principal, des connecteurs, des éléments auxiliaires (joint télescopique, joint flexible, embase de commande,... ;
  • caractéristiques des lignes auxiliaires périphériques ;
  • caractéristiques des flotteurs ;
  • conditions maritimes, courants, profondeur, vents, houle,... ;
  • données liées au programme du forage : densité du fluide de forage, diamètre du tube interne.
The set of blocks 20 shows diagrammatically the data inputs of calculations:
  • characteristics of the main tube, connectors, auxiliary elements (telescopic seal, flexible seal, control base, ...;
  • characteristics of peripheral auxiliary lines;
  • float characteristics;
  • maritime conditions, currents, depth, winds, swell, ...;
  • data related to the drilling program: density of the drilling fluid, diameter of the internal tube.

A partir de ces données, nullement exhaustives, on choisit a priori un diamètre de tube interne, son épaisseur Ei et une flottabilité déterminée par le paramètre C de compensation. Cette première architecture permet de calculer en mode déconnecté DM la marge de sécurité M représentant la marge de tension entre la tension amplifiée Ta du riser compte tenu du pilonnement du support et le poids apparent du riser W. Si cette marge est négative, ou jugée insuffisante, on boucle par la ligne 21 en diminuant la valeur de la compensation C. Si la marge est jugée trop importante, on boucle par la ligne 22 en augmentant la compensation C. On peut prendre, par exemple une marge d'environ 20 tonnes.From these data, which are by no means exhaustive, we choose a priori inner tube diameter, its thickness Ei and a buoyancy determined by the compensation parameter C. This first architecture makes it possible to calculate in disconnected mode DM the safety margin M representing the margin of voltage between the amplified voltage Ta of the riser taking into account the heaving of the support and the apparent weight of the riser W. If this margin is negative, or judged insufficient, we loop through line 21 by decreasing the value of the compensation C. If the margin is considered too large, we loop through the line 22 by increasing the compensation C. We can take, for example, a margin of about 20 tonnes.

Après ces étapes en mode déconnecté DM, on passe au calcul des contraintes de Von-Mises VM en mode connecté CM représenté par le bloc 23, à l'aide de l'architecture de riser précédemment déterminée.After these steps in DM disconnected mode, we go to the calculation of Von-Mises VM constraints in connected mode CM represented by block 23, using the riser architecture previously determined.

Les multiples flèches 24 représentent les données prises en comptes pour ce calcul des contraintes de Von-Mises, par exemple :

  • grades d'acier des tubes ;
  • tension en pied de riser (par exemple 100 t) ;
  • tolérance d'épaisseur du tube principal ;
  • prise en compte d'une diminution d'épaisseur (environ 1/16 de pouce (1 pouce=25,4 mm)) à cause de la corrosion ;
  • densité maximale de la boue ;
  • perte de flottabilité d'environ 3% ;
  • pressurisation des lignes auxiliaires.
The multiple arrows 24 represent the data taken into account for this calculation of the Von-Mises constraints, for example:
  • steel grades of tubes;
  • tension at the foot of the riser (for example 100 t);
  • thickness tolerance of the main tube;
  • taking into account a reduction in thickness (approximately 1/16 of an inch (1 inch = 25.4 mm)) due to corrosion;
  • maximum mud density;
  • loss of buoyancy of approximately 3%;
  • pressurization of auxiliary lines.

Dans le cas où dans toutes les sections du riser, les contraintes de Von Mises sont inférieures à 2/3 de la limite élastique de l'acier du tube principal, on boucle le calcul par la ligne 25, en diminuant l'épaisseur du tube de l'architecture précédemment considérée, par exemple d'environ 1/16 de pouce (1,5875 mm) pour optimiser le riser. Dans le cas où les contraintes sont supérieures à 2/3 de la limite élastique de l'acier du tube principal, on boucle le calcul par la ligne 26, en augmentant l'épaisseur du tube de l'architecture précédemment considérée.In the case where in all sections of the riser, the constraints of Von Stakes are less than 2/3 of the yield strength of the main tube steel, we complete the calculation by line 25, reducing the thickness of the tube the architecture previously considered, for example about 1/16 of an inch (1.5875 mm) to optimize the riser. In the case where the constraints are greater than 2/3 of the elastic limit of the steel of the main tube, we loop the calculation by line 26, increasing the thickness of the architecture tube previously considered.

Ces itérations successives assurent une optimisation de l'ensemble du riser, y compris des éléments de flottabilité.These successive iterations ensure optimization of the entire riser, including buoyancy elements.

Le bloc 27 schématise l'obtention de l'architecture finale, répondant au cahier des charges et des normes en vigueur.Block 27 shows schematically the obtaining of the final architecture, responding to the specifications and standards in force.

L'ensemble des étapes 28 peut être assimilé à des vérifications en calculant la tension en tête du riser TT en prenant en compte l'épaisseur nominale EN du tube, sans corrosion et en considérant une perte de flottabilité de 3%. A partir de TT, on vérifie (bloc 29) si les connecteurs sont compatibles avec cette tension, et si les moyens de tensionnement du support flottant sont suffisants.All of the steps 28 can be compared to verifications in calculating the tension at the head of the TT riser taking into account the thickness nominal EN of the tube, without corrosion and considering a loss of buoyancy 3%. From TT, we check (block 29) if the connectors are compatible with this tension, and if the tensioning means of the floating support are enough.

En dernière étape de vérification, l'architecture du riser obtenu est vérifié en dynamique en utilisant le logiciel DeepLines™ (IFP), ou équivalent.As a final verification step, the architecture of the riser obtained is dynamically verified using DeepLines ™ software (IFP), or equivalent.

Claims (8)

Méthode pour dimensionner un ensemble prolongateur (1) pour le forage en mer reliant une tête de puits sous-marine (2) à un support flottant (7) comprenant un tube principal (8), dans laquelle on effectue les étapes suivantes: a) on choisit une architecture complète de l'ensemble prolongateur à partir d'un cahier des charges, notamment en se fixant l'épaisseur du tube principal et des moyens de flottaison, et on calcule le poids apparent de cet ensemble, b) on détermine une marge de sécurité sur la tension en tête dudit ensemble, en mode déconnecté de la tête du puits, compte tenu du poids apparent et de la tension amplifiée en tête par les mouvements du support flottant auquel est suspendu ledit ensemble, c) dans le cas où ladite marge correspond à une valeur proche d'une valeur déterminée, on calcule les contraintes de Von-Mises dans toutes les sections du tube, en mode connecté à la tête du puits, d) dans le cas où lesdites contraintes sont proche d'un critère déterminé en relation avec la limite élastique du matériau du tube : on obtient l'architecture de l'ensemble prolongateur et on vérifie la compatibilité de chaque composant de l'ensemble prolongateur à la tension maximale, ainsi que la fatigue en dynamique dudit ensemble. Method for dimensioning an extension assembly (1) for offshore drilling connecting an underwater wellhead (2) to a floating support (7) comprising a main tube (8), in which the following steps are carried out: a) a complete architecture of the extension assembly is chosen from a specification, in particular by setting the thickness of the main tube and the flotation means, and the apparent weight of this assembly is calculated, b) a safety margin is determined on the tension at the head of said assembly, in disconnected mode from the well head, taking into account the apparent weight and the tension amplified at the head by the movements of the floating support to which said assembly is suspended, c) in the case where said margin corresponds to a value close to a determined value, the Von-Mises stresses are calculated in all the sections of the tube, in mode connected to the well head, d) in the case where said constraints are close to a criterion determined in relation to the elastic limit of the tube material: the architecture of the extension assembly is obtained and the compatibility of each component of the extension assembly is checked. the maximum tension, as well as the fatigue in dynamics of said assembly. Méthode selon la revendication 1, dans laquelle on modifie les moyens de flottaison pris en compte dans l'étape a) lorsque ladite marge de tension en mode déconnecté est éloignée de ladite valeur déterminée, de façon à approcher la valeur de ladite marge.Method according to claim 1, in which the means for modifying buoyancy taken into account in step a) when said tension margin in disconnected mode is far from said determined value, so that approach the value of said margin. Méthode selon la revendication 2, dans laquelle on modifie les moyens de flottaison en faisant varier au moins l'un des paramètres suivants : le nombre de flotteurs, la répartition des flotteurs, le diamètre des flotteurs, la masse volumique du matériau des flotteurs.Method according to claim 2, in which the means for modifying flotation by varying at least one of the following parameters: the number of floats, distribution of floats, diameter of floats, the density of the float material. Méthode selon l'une des revendications précédentes, dans laquelle on fait varier l'épaisseur du tube principal lorsque les contraintes de Von-Mises calculées à l'étape c) ne respectent pas ledit critère déterminé.Method according to one of the preceding claims, in which: vary the thickness of the main tube when the Von-Mises constraints calculated in step c) do not respect said determined criterion. Méthode selon la revendication 4, dans laquelle ledit critère impose que les contraintes de Von-Mises soient inférieures à 2/3 de la limite élastique de l'acier du tube principal.The method of claim 4, wherein said criterion requires that the Von-Mises stresses are less than 2/3 of the elastic limit of the main tube steel. Méthode selon la revendication 5, dans laquelle on augmente l'épaisseur du tube lorsque lesdites contraintes sont supérieures à environ 2/3 de la limite élastique, et en ce que l'on diminue l'épaisseur du tube lorsque lesdites contraintes sont inférieures à environ 2/3 de la limite élastique.Method according to claim 5, in which the thickness of the tube when said stresses are greater than about 2/3 of the limit elastic, and in that the thickness of the tube is reduced when said stresses are less than about 2/3 of the elastic limit. Méthode selon l'une des revendications précédentes, dans laquelle on effectue les étapes a) et b) en prenant en compte une perte d'épaisseur du tube principal et une perte de flottabilité des moyens de flottaison. Method according to one of the preceding claims, in which performs steps a) and b) taking into account a loss of thickness of the main tube and a loss of buoyancy of the flotation means. Méthode selon l'une des revendications précédentes, dans laquelle ladite marge est au moins égale à 20 t.Method according to one of the preceding claims, wherein said margin is at least equal to 20 t.
EP02291245A 2001-05-25 2002-05-21 Method for dimensioning a drilling riser Expired - Lifetime EP1260670B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0107007A FR2825116B1 (en) 2001-05-25 2001-05-25 METHOD FOR DIMENSIONING A DRILLING RISER
FR0107007 2001-05-25

Publications (2)

Publication Number Publication Date
EP1260670A1 true EP1260670A1 (en) 2002-11-27
EP1260670B1 EP1260670B1 (en) 2008-01-02

Family

ID=8863734

Family Applications (1)

Application Number Title Priority Date Filing Date
EP02291245A Expired - Lifetime EP1260670B1 (en) 2001-05-25 2002-05-21 Method for dimensioning a drilling riser

Country Status (6)

Country Link
US (1) US7630866B2 (en)
EP (1) EP1260670B1 (en)
AT (1) ATE382771T1 (en)
DE (1) DE60224323D1 (en)
DK (1) DK1260670T3 (en)
FR (1) FR2825116B1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2474468A1 (en) * 2006-11-08 2012-07-11 Acergy France SA Hybrid riser tower
CN103958818A (en) * 2011-11-29 2014-07-30 韦尔斯特里姆国际有限公司 Buoyancy compensating element and method
CN108961430A (en) * 2018-06-27 2018-12-07 山东大学 A kind of acquisition methods and system of the floating support component of arbitrary shaped body

Families Citing this family (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2839339B1 (en) * 2002-05-03 2004-06-04 Inst Francais Du Petrole METHOD FOR DIMENSIONING A RISER ELEMENT WITH INTEGRATED AUXILIARY DUCTS
GB0227851D0 (en) * 2002-11-29 2003-01-08 Stolt Offshore Sa Subsea structure and methods of construction and installation thereof
US7383885B2 (en) * 2004-09-22 2008-06-10 William von Eberstein Floatation module and method
US20080302535A1 (en) * 2007-06-08 2008-12-11 David Barnes Subsea Intervention Riser System
US7766580B2 (en) * 2008-02-14 2010-08-03 National Oilwell Varco, L.P. Energy managing keel joint
FR2937676B1 (en) * 2008-10-29 2010-11-19 Inst Francais Du Petrole METHOD FOR LIFTING A UPRIGHT COLUMN WITH OPTIMIZED WEAR
US8322438B2 (en) * 2009-04-28 2012-12-04 Vetco Gray Inc. Riser buoyancy adjustable thrust column
US8443896B2 (en) 2009-06-04 2013-05-21 Diamond Offshore Drilling, Inc. Riser floatation with anti-vibration strakes
US9670740B2 (en) * 2015-02-26 2017-06-06 Exxonmobil Upstream Research Company Drilling riser with distributed buoyancy
US9908594B2 (en) 2016-04-29 2018-03-06 Expert E&P Consultants, L.L.C. Flotation system and method
US10167677B2 (en) 2016-04-29 2019-01-01 William von Eberstein Flotation system and method
GB2551816B (en) * 2016-06-30 2019-04-03 Trelleborg Offshore Uk Ltd Stacked buoyancy module for a subsea member
CN107167390B (en) * 2017-05-22 2024-02-20 中国海洋石油集团有限公司 Deep water underwater wellhead fatigue test device
CN108595767B (en) * 2018-03-27 2022-04-05 浙江工业大学 Reliability-based marine riser VIV fatigue safety coefficient determination method
BR102018014298B1 (en) 2018-07-13 2021-12-14 Petróleo Brasileiro S.A. - Petrobras SYSTEM AND METHOD OF SUPPORTING THE OPERATION OF SUBSEA INSTALLATIONS FOR 3D RECONSTRUCTION OF FLEXIBLE LINES DURING A DIRECT VERTICAL CONNECTION OPERATION
CN110069847B (en) * 2019-04-18 2023-10-13 中国石油大学(华东) Pressure test optimization decision-making method for auxiliary pipeline of deepwater drilling riser

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2342938A (en) * 1998-10-13 2000-04-26 Inst Francais Du Petrole Offshore drill pipe riser with adjustable buoyancy
WO2000058598A1 (en) * 1999-03-25 2000-10-05 Pgs Offshore Technology As System with a guide frame for petroleum production risers; a guide frame for risers; riser buoyancy elements and a semi-submersible production platform

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2653162B1 (en) * 1989-10-17 1995-11-17 Inst Francais Du Petrole RISING COLUMN FOR LARGE DEPTH OF WATER.

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2342938A (en) * 1998-10-13 2000-04-26 Inst Francais Du Petrole Offshore drill pipe riser with adjustable buoyancy
WO2000058598A1 (en) * 1999-03-25 2000-10-05 Pgs Offshore Technology As System with a guide frame for petroleum production risers; a guide frame for risers; riser buoyancy elements and a semi-submersible production platform

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
FERNANDES: "UP-TO-DATE SPREADSHEET PROGRAM FOR PRELIMINARY ANALYSIS OF FLEXIBLE AND STEEL CATENARY RISERS USING CATENARY CONCEPTS", September 1997, COMPUTATIONAL MECHANICS PUBLICATION, SOUTHAMPTON BOSTON, XP001059619 *
GARDNER, T., KOTCH, M.: "Dynamic Analysis of Risers by the Element Method", SPE 6310, 3 May 1976 (1976-05-03), XP002188782 *
WYBRO, P., DAVIES, K.: "The Dorado Field Production Risers", SPE 11549, December 1982 (1982-12-01), XP002188781 *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2474468A1 (en) * 2006-11-08 2012-07-11 Acergy France SA Hybrid riser tower
CN103958818A (en) * 2011-11-29 2014-07-30 韦尔斯特里姆国际有限公司 Buoyancy compensating element and method
US9151121B2 (en) 2011-11-29 2015-10-06 Ge Oil & Gas Uk Limited Buoyancy compensating element and method
CN103958818B (en) * 2011-11-29 2017-05-10 通用电气石油和天然气英国有限公司 Buoyancy compensating assembly and method
CN108961430A (en) * 2018-06-27 2018-12-07 山东大学 A kind of acquisition methods and system of the floating support component of arbitrary shaped body
CN108961430B (en) * 2018-06-27 2020-03-27 山东大学 Method and system for acquiring floating support assembly of object in any shape

Also Published As

Publication number Publication date
US20030026663A1 (en) 2003-02-06
US7630866B2 (en) 2009-12-08
DK1260670T3 (en) 2008-05-13
DE60224323D1 (en) 2008-02-14
FR2825116B1 (en) 2003-12-05
FR2825116A1 (en) 2002-11-29
EP1260670B1 (en) 2008-01-02
ATE382771T1 (en) 2008-01-15

Similar Documents

Publication Publication Date Title
EP1260670B1 (en) Method for dimensioning a drilling riser
EP1073823B1 (en) Method and device for linking surface to the seabed for a submarine pipeline installed at great depth
FR2766869A1 (en) DEVICE FOR TRANSFERRING FLUID BETWEEN A SUBSEA GROUND EQUIPMENT AND A SURFACE UNIT
EP2844820B1 (en) Installation comprising seabed-to-surface connections of the multi-riser hybrid tower type, including positive-buoyancy flexible pipes
OA12814A (en) Système de colonne mo ntante flexible.
CA1093325A (en) Device for setting and centering an off-shore gravity structure over existing units anchored in the seabed
OA12820A (en) Système de colonne montante reliant deux installations sous-marines fixes à une unité de surface flottante.
EP2785952B1 (en) Flexible multiple seabed-to-surface connections facility on at least two levels
US7104329B2 (en) Marine bottomed tensioned riser and method
EP1194677B1 (en) Device connecting the sea floor with the surface comprising a submarine pipeline attached to at least one floater
EP2571753B1 (en) Seabed-to-surface linking equipment including a flexible pipe guiding structure
FR2808263A1 (en) DEVICE FOR TRANSFERRING A FLUID BETWEEN AT LEAST TWO FLOATING SUPPORTS
CN101939491B (en) Self-standing riser system having multiple buoyancy chambers
FR3005484A1 (en) DEVICE FOR ANCHORING A CHUTE SUPPORT OF A FUND-SURFACE INSTALLATION
FR2837870A1 (en) METHOD AND DEVICE FOR DETECTING CHARACTERIQTICS OF A FLUID PRESENT IN A DIRECTORY OF A RISING COLUMN
EP0437588B1 (en) Assembly comprising an extension tube and a sleeving conduit inside it
EP1509671B1 (en) Multi-catenary type rising column
EP3446957A1 (en) Barge with pile systems for beaching and damping the effects of swell
EP3371498B1 (en) Pipe, method for regulating the height of the water in the pipe, and associated installation method
Kyllingstad Buckling of Tubular Strings in Open Sea
FR2857690A1 (en) SEA DRILLING SYSTEM COMPRISING A HIGH PRESSURE RISE COLUMN
Felisita et al. Comparison of umbilical installation analysis using two irregular wave spectra
NO345972B1 (en) A wellhead system
Stokes et al. Tailoring the TLP–Evolution and Adaptation of the Concept
Smith Technical and Economic Factors Affecting Future Production of Oil and Gas in Deep Waters and Hostile Environments

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR

AX Request for extension of the european patent

Free format text: AL;LT;LV;MK;RO;SI

17P Request for examination filed

Effective date: 20030527

AKX Designation fees paid

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR

17Q First examination report despatched

Effective date: 20050609

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

GRAC Information related to communication of intention to grant a patent modified

Free format text: ORIGINAL CODE: EPIDOSCIGR1

GRAS Grant fee paid

Free format text: ORIGINAL CODE: EPIDOSNIGR3

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU MC NL PT SE TR

REG Reference to a national code

Ref country code: GB

Ref legal event code: FG4D

Free format text: NOT ENGLISH

REG Reference to a national code

Ref country code: IE

Ref legal event code: FG4D

Free format text: LANGUAGE OF EP DOCUMENT: FRENCH

REG Reference to a national code

Ref country code: CH

Ref legal event code: EP

REF Corresponds to:

Ref document number: 60224323

Country of ref document: DE

Date of ref document: 20080214

Kind code of ref document: P

REG Reference to a national code

Ref country code: DK

Ref legal event code: T3

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080102

NLV1 Nl: lapsed or annulled due to failure to fulfill the requirements of art. 29p and 29m of the patents act
GBV Gb: ep patent (uk) treated as always having been void in accordance with gb section 77(7)/1977 [no translation filed]
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FI

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080102

Ref country code: ES

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080413

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: AT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080102

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: PT

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080602

REG Reference to a national code

Ref country code: IE

Ref legal event code: FD4D

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080102

Ref country code: SE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080402

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

BERE Be: lapsed

Owner name: INSTITUT FRANCAIS DU PETROLE

Effective date: 20080531

26N No opposition filed

Effective date: 20081003

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080102

Ref country code: MC

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20080531

REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: CH

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20080531

Ref country code: DE

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080403

Ref country code: LI

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20080531

REG Reference to a national code

Ref country code: FR

Ref legal event code: ST

Effective date: 20090119

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: BE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20080531

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: FR

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20080602

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: CY

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080102

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LU

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20080521

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: TR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080102

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 20080403

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DK

Payment date: 20130521

Year of fee payment: 12

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: IT

Payment date: 20130522

Year of fee payment: 12

REG Reference to a national code

Ref country code: DK

Ref legal event code: EBP

Effective date: 20140531

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DK

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20140531

Ref country code: IT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20140521