WO1998034829A1 - Dispositif d'ancrage geostationnaire pour vaisseau - Google Patents

Dispositif d'ancrage geostationnaire pour vaisseau Download PDF

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Publication number
WO1998034829A1
WO1998034829A1 PCT/NO1998/000041 NO9800041W WO9834829A1 WO 1998034829 A1 WO1998034829 A1 WO 1998034829A1 NO 9800041 W NO9800041 W NO 9800041W WO 9834829 A1 WO9834829 A1 WO 9834829A1
Authority
WO
WIPO (PCT)
Prior art keywords
well
anchoring arrangement
arrangement according
elements
rotating part
Prior art date
Application number
PCT/NO1998/000041
Other languages
English (en)
Norwegian (no)
Inventor
Leiv Wanvik
Original Assignee
Kværner Oil & Gas A.S.
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 Kværner Oil & Gas A.S. filed Critical Kværner Oil & Gas A.S.
Priority to AU62312/98A priority Critical patent/AU6231298A/en
Publication of WO1998034829A1 publication Critical patent/WO1998034829A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B21/00—Tying-up; Shifting, towing, or pushing equipment; Anchoring
    • B63B21/50—Anchoring arrangements or methods for special vessels, e.g. for floating drilling platforms or dredgers
    • B63B21/507—Anchoring arrangements or methods for special vessels, e.g. for floating drilling platforms or dredgers with mooring turrets

Definitions

  • the invention relates to a geostationary anchoring system for a vessel, comprising a rotating part that is rotatably supported about a vertical axis in a well in a vessel and mooring lines extending from the rotating part to a seabed.
  • anchor e.g., a production ship for the production of hydrocarbons with the aid of a geostationary rotating part which is recessed into the ship's hull, usually in the foreship.
  • Mooring lines run out from the rotating part preferably in a radial pattern and down to anchors on the seabed.
  • the rotating part is supported at weather deck level with separate bearings for vertical forces and radial lateral forces. Owing to the great stresses from dynamics, wave pressure variation, dead weight, mooring and riser forces, the load on the points of support of the rotating part against the ship and the accompanying friction will be so great that the rotating part normally will not be capable of rotating relative to the ship in a controlled manner. It is therefore common to have systems which actively turn the rotating part.
  • the risers as a rule flexible risers, are often attached to a swivel arrangement which transfers the production to an on-deck processing plant.
  • a swivel solution When a swivel solution is used, very expensive limits of tolerance are set for the global dimensions of the rotating part and the associated points of support provided in the ship's hull. "Eccentricity" in the centre of the rotating part will cause large forces in pipelines which conduct fluids under great pressure up to the swivel arrangement.
  • Today's swivel solutions are dependent upon these forces being small since otherwise wear on gasket surfaces and leaks would easily occur.
  • the mooring lines are passed into the rotating part via guide wheels secured to the lower portion of the rotating part. Access for inspection and replacement of such guide wheels in the bottom region of the rotating part is very limited, but a replacement technique with the use of careening is known.
  • the object of the present invention is to provide an arrangement which will contribute to a better solution of the above-identified weaknesses.
  • a geostationary anchoring arrangement for a vessel, comprising a rotating part which is rotatably supported about a vertical axis in a well in a vessel, and mooring lines extending from the rotating part to a seabed, which anchoring arrangement is characterised in that the rotating part consists of a number of separate elements arranged in a circular-cylindrical garland around the vertical axis of rotation, which elements are interconnected flexibly so that they can move in the well as a virtually united rigid annular body.
  • a division or segmentation of this kind into single elements with flexible interconnection makes it possible to absorb deviations from the defined theoretical geometry (tolerances/deflections/wear) without there being any danger of the rotating part being exposed to locking forces as a whole body or between the elements.
  • the individual elements impart a direct transfer of riser and mooring forces limited to the immediately assigned support on the ship.
  • the individual support of force which is due to the division into individual elements means that coercive forces as a result of the deformation of the vessel are largely avoided.
  • the weight of the rotating part will also be capable of being reduced drastically, and a realistic estimate is a weight reduction of 30%, perhaps as much as 50% and more compared with the classical, known rotating part embodiments.
  • Each element may to advantage be in the form of an elongatedly constructed element which is flexibly interconnected to adjacent elements at the top and the bottom.
  • the flexible interconnection may be in the form of a true swivel joint.
  • the flexible interconnection at the top may be in the form of welded or interconnected plates, which form horizontal plating.
  • each element may include an upper part, a lower part and one or more vertically extending connecting parts therebetween.
  • the upper part constitutes a bearing component for interaction with a bearing surface provided around the well
  • the lower part constitutes a second bearing component for interaction with a bearing surface provided around the well
  • An especially advantageous embodiment according to the invention is one where there is provided between the adjacent elements a jacking device with which the elements can be forced apart, so that the annular body can generate friction against a surrounding cylindrical surface in the well for controlled locking of relative tangential movement.
  • the bearing surface inside the well (Fig. 12) is given a conical design having an angle not exceeding the angle of friction with a view to obtaining additional progressive and geometrically conditioned increase in frictional force against the bearing raceway in the event of extreme vertical loads on the elements, collectively or individually.
  • the individual elements may have two-sided upper support in the well.
  • each element can be an elongatedly constructed element having two or more parallel, vertical tubular parts which are connected to one another at the top and at the bottom.
  • the elements at the top are interconnected by means of plating, each element under this plating having a support structure with separate bearing pads for contact with a rotary bearing around the well, where the support structure is designed to function as a transmission device for distributing discrete loads from each one of the guide pipes out to a plurality of bearing pads in such manner as to avoid uneven loading or overloading of the individual bearing pads.
  • Fig. 1 is a schematic vertical section through a geostationary anchoring arrangement according to the invention
  • Fig. 2 is a plan view of the arrangement in Fig. 1 ;
  • Fig. 3 is a section along the line III-III in Fig. 1 ;
  • Fig. 4 is a plan view of a modified geostationary anchoring arrangement according to the invention;
  • Fig. 5 is a schematic vertical section through another embodiment of the invention.
  • Fig. 6 is a perspective section of the embodiment according to Fig. 4;
  • Fig. 7 is a plan view of the embodiment in Fig. 6, without plating;
  • Fig. 8 is a perspective section, seen from below, of an arrangement as in Figs. 4, 6 and
  • Fig. 9 is a schematic vertical section through a geostationary anchoring arrangement according to the invention, with swivel connection for the risers;
  • Fig. 10 is a schematic vertical section through a geostationary anchoring arrangement according to the invention, with a drag chain arrangement for the risers;
  • Fig. 11 is a schematic vertical section through a geostationary anchoring arrangement according to the invention, during a possible drilling operation; and Fig. 12 is a schematic vertical section through an embodiment having a conical bearing surface in the well.
  • a part of a ship's hull is indicated by means of the reference numeral 1.
  • the ship's hull 1 there is a vertical through-going well 2.
  • the well 2 there is provided a plurality of separate, elongate elements 3. As shown in Figs. 2 and 3, these elements 3 are arranged in a circular-cylindrical garland along the well wall.
  • each element 3 is constructed having an upper plate 4, a lower plate 5, and pipes 6 extending therebetween, for guiding mooring lines 7, and pipes 8 for guiding risers 9.
  • the upper plates 4 are connected to each other with the aid of joints 10 having horizontal swivelling axes.
  • the lower plates 5 are interconnected by means of joints 11 , these also having horizontal swivelling axes.
  • the joints 10 are made in the form of fish plates 12 which are pivotally connected to the respective adjacent plate 4 so that each joint 10 is a fished joint having two swivelling axes.
  • the individual joints 11 are made in the form of pin- and-lug hinges.
  • a rotating part in the well 2 consisting of a plurality of separate elements 3 arranged in a circular-cylindrical garland around a vertical axis (the vertical centre line of the well 2).
  • the elements 3 are interconnected by means of the joints 10, 11 so that they can move in the well 2 as a virtually united rigid, annular body.
  • An annular horizontal bearing raceway 14 for the upper plates 4 is provided on the ship's 1 deck 13.
  • An annular vertical bearing raceway 15 is provided for the plates 5 in the well 2.
  • Bearing pads here are indicated by means of reference numeral 16.
  • the connecting joints arranged between the elements 3 in the cylindrical garland or rotating part may be constructed in many other ways, provided that they function in a satisfactory manner to couple the elements so that they can move in the well 2 as a virtually united rigid unit. It may thus be a favourable embodiment to collect the upper plates 4 into a single ring, as is shown in Fig. 4.
  • the plates 4 are welded together as indicated at 17, so that there is a rotating part which at the top consists of plating from where pipes 6, 8 extend down to the hinge-connected 11 lower plates 5.
  • the upper plating which is formed by the upper plates 4, can be proportioned and made so that the plating will be capable of following the deformation motions of the ship's hull, and especially deformation motions in the deck 13, whether they are horizontal (ovalisation of the well opening) or vertical (out of co-planar position).
  • the plating may be constructed in a manner other than that shown by lateral welding of the plates 4.
  • the plating per se could be a uniform plating body, or for example, pairs of the upper plates 4 could be joined and made in the form of uniform bodies, with an accompanying reduction in the number of weld joints 17. What is essential is that the upper plating is so flexible that it can follow the motions of the ship and thus the bearing raceway 14 and give the individual elements 3 the necessary support and relative freedom.
  • upper and lower plates 4, 5 could in practice be constructed plates, for example, chest or box structures, and the upper and lower plates 4, 5 may of course be connected to one another in a way other than that illustrated.
  • the pipes 6, 8 instead of the pipes 6, 8, a single pipe may be provided, or a truss-like construction may be used.
  • the rotating part may to advantage be constructed so that some of the elements 3 serve as guides for and fixing of mooring lines 7, whilst others serve as guides for risers 9 and others again merely act as structural components of the rotating part.
  • the upper plates 4 have been given a structural form which provides each element with a great torsional pliancy.
  • plating of welded 17 plates 4 is constructed.
  • the individual pipes 6, 8 run through these plates.
  • Under each of the welded plates 4 there is constructed a separate support structure 21, see Figs. 7 and 8 (where the plates 4 have been omitted! .
  • Peculiar to this support structure 21, is that it is made having, e.g., four bearing pads 22 - 25 designed for bearing interaction with the annular bearing raceway 14 (see Fig. 1).
  • the purpose of the illustrated design is to achieve a load of maximum conformity on all the load pads 22 - 25 along the periphery of the whole element through a transmission system of supporting beams 21.
  • Fig. 8 shows how the lower plates 5 optionally may be made - in the form of a box - or a chest structure having bearing pads 26 for bearing interaction with the annular bearing raceway 15 in the well 2 (see Fig. 1).
  • Fig. 9 shows how the invention can be accomplished in connection with so-called swivel connection 26 of risers 9, in a known way per se, and
  • Fig. 10 shows the invention implemented in connection with a drag chain device 27, which is also known per se.
  • Fig. 11 shows the invention effected as a rotating part, where a drilling operation can be carried out through the well 2.
  • a drilling derrick 28 is located on a gantry or bridge structure 29 on the ship's deck 13.
  • a drilling string is indicated by means of the reference numeral 30.
  • a tension adjusting device for the mooring line 7 is shown at 31.
  • the flexibility of the rotating part according to the invention allows a change in diameter in the lower support area (at 15 in Fig. 1) so that the rotating part can be checked or locked against rotation.
  • Such locking is especially favourable when vessel and rotating part move in the sea, in order to avoid small movements which cause wear (chafing) on parts in contact with one another.
  • Such change in diameter may, for example, be carried out by inserting a jacking device between adjacent elements 3 as shown in Fig. 3, where suitable jacks 32 are indicated between an element 3 and the two adjacent elements 3.
  • the annular circumference may also be constricted by means of the jacking device to facilitate rotation.
  • a net force contact against one side of the well 2 where the mooring forces act will also be obtained. Friction from said net force contact can be reduced considerably by passing lubricating water under high pressure to the bearing surfaces 16 through suitable piping from the rotating part.
  • a large increase in tangential and vertical locking capacity can be obtained if a conical bearing surface 15' is used between the rotating part and the well wall as shown in Fig. 12.
  • This angle should be smaller than the angle of friction so that self-locking occurs on the use of clamp bodies 32 and also that the deformation of the rotating part in a vertical direction results in geometrically progressive locking of the rotating body, so that a controlled distribution of force is obtained between the lower rotating part and the other portions of the rotating part which rest on the horizontal rotary raceway on the ship's deck.
  • This can be accomplished by using co-rotating flexible bearing pads, shown as 16 in Fig. 3, with a desired composition of axial and shear deformation rigidity.
  • Measures are preferably taken which allow controlled shifting or turning of the rotating part. This may, for example, take place with the aid of a toothed-rim drive gear device (not shown) or using other known means. There might be a need for lubrication of the bearings. A water-high pressure system, attached, for instance, to the bearing pads 22 - 25, would be a favourable solution in this respect.
  • the segmentation of the rotating part makes it possible to remove, e.g., one element and replace it with another in connection with maintenance or faults.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Ocean & Marine Engineering (AREA)
  • Earth Drilling (AREA)

Abstract

Un dispositif d'ancrage géostationnaire pour vaisseau comprend une partie rotative qui est montée rotative sur un axe vertical situé dans le puits (2) d'un vaisseau (1) et des lignes d'ancrage (7) s'étendant depuis la partie rotative jusqu'au fond marin. La partie rotative consiste en plusieurs éléments séparés (3) disposés en guirlande cylindrique et circulaire autour de l'axe vertical de rotation, lesdits éléments (3) étant reliés entre eux de manière souple de sorte qu'ils puissent se déplacer dans le puits (2) comme un corps annulaire rigide sensiblement monobloc.
PCT/NO1998/000041 1997-02-05 1998-02-05 Dispositif d'ancrage geostationnaire pour vaisseau WO1998034829A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU62312/98A AU6231298A (en) 1997-02-05 1998-02-05 Geostationary anchoring arrangement for a vessel

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NO970508 1997-02-05
NO970508A NO306334B1 (no) 1997-02-05 1997-02-05 Geostasjonært oppankringsarrangement for et fartöy

Publications (1)

Publication Number Publication Date
WO1998034829A1 true WO1998034829A1 (fr) 1998-08-13

Family

ID=19900344

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NO1998/000041 WO1998034829A1 (fr) 1997-02-05 1998-02-05 Dispositif d'ancrage geostationnaire pour vaisseau

Country Status (3)

Country Link
AU (1) AU6231298A (fr)
NO (1) NO306334B1 (fr)
WO (1) WO1998034829A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2797843A1 (fr) 1999-09-01 2001-03-02 Dumez Gtm Barge mobile a jambes tendues pour travaux nautiques a moyennes profondeurs

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4698038A (en) * 1984-10-17 1987-10-06 Key Ocean Services, Inc. Vessel mooring system and method for its installation
US4701143A (en) * 1984-10-17 1987-10-20 Key Ocean Services, Inc. Vessel mooring system and method for its installation
NO165285B (no) * 1987-12-08 1990-10-15 Kvaerner Brug Kjoleavdelning Dreietaarn.
US5359957A (en) * 1991-09-30 1994-11-01 Norsk Hydro A.S. Turret for drilling or production ship
US5515804A (en) * 1995-08-21 1996-05-14 Imodco, Inc. Bearing support for single point terminal

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4698038A (en) * 1984-10-17 1987-10-06 Key Ocean Services, Inc. Vessel mooring system and method for its installation
US4701143A (en) * 1984-10-17 1987-10-20 Key Ocean Services, Inc. Vessel mooring system and method for its installation
NO165285B (no) * 1987-12-08 1990-10-15 Kvaerner Brug Kjoleavdelning Dreietaarn.
US5359957A (en) * 1991-09-30 1994-11-01 Norsk Hydro A.S. Turret for drilling or production ship
US5515804A (en) * 1995-08-21 1996-05-14 Imodco, Inc. Bearing support for single point terminal

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2797843A1 (fr) 1999-09-01 2001-03-02 Dumez Gtm Barge mobile a jambes tendues pour travaux nautiques a moyennes profondeurs
WO2001015969A1 (fr) 1999-09-01 2001-03-08 Vinci Construction Grands Projets Barge mobile a jambes tendues pour travaux nautiques a moyennes profondeurs

Also Published As

Publication number Publication date
AU6231298A (en) 1998-08-26
NO970508L (no) 1998-08-06
NO970508D0 (no) 1997-02-05
NO306334B1 (no) 1999-10-25

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