WO1998040602A1 - Procede et dispositif d'agencement et d'installation d'une structure sur un fond marin - Google Patents

Procede et dispositif d'agencement et d'installation d'une structure sur un fond marin Download PDF

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Publication number
WO1998040602A1
WO1998040602A1 PCT/NO1998/000060 NO9800060W WO9840602A1 WO 1998040602 A1 WO1998040602 A1 WO 1998040602A1 NO 9800060 W NO9800060 W NO 9800060W WO 9840602 A1 WO9840602 A1 WO 9840602A1
Authority
WO
WIPO (PCT)
Prior art keywords
underwater installation
line
installation
fitted
tensioning means
Prior art date
Application number
PCT/NO1998/000060
Other languages
English (en)
Inventor
Leif Botolf Hesle
Original Assignee
Abb Offshore Technology As
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 Abb Offshore Technology As filed Critical Abb Offshore Technology As
Priority to GB9920435A priority Critical patent/GB2338739A/en
Publication of WO1998040602A1 publication Critical patent/WO1998040602A1/fr

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Classifications

    • E—FIXED CONSTRUCTIONS
    • E21—EARTH OR ROCK DRILLING; MINING
    • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
    • E21B41/00—Equipment or details not covered by groups E21B15/00 - E21B40/00
    • E21B41/10—Guide posts, e.g. releasable; Attaching guide lines to underwater guide bases

Definitions

  • the present invention is concerned with a procedure for the launch and sinking of a structure under water.
  • the procedure according to the invention additionally permits the sinking of the structure in a controlled manner, after which the structure is positioned, oriented and fitted in the desired location.
  • the invention is particularly concerned with a method for the launch, sinking, positioning and fitting of a protective structure over an underwater installation, such that the protective structure is to be fixed in the correct position and correct orientation in relation to the installation which it is intended to protect, that at least one guide line is attached in advance to the underwater installation by at least one attachment device provided thereon for the purpose and passes through purpose-made openings in the structure, and that the protective structure is lowered down the guide line towards the underwater installation.
  • the invention is further concerned with a device specially designed for the implementation of such a procedure.
  • a system is known in the prior art for controlling the vertical motion of a body which is sunk into water down a guide line, wherein a friction brake acts between the body and the guide line and said friction brake can be operated mechanically.
  • US patent 3,465,531 in which it is shown how a process pack can be lowered along two guide lines which are attached at their top end to a boom supported by a vessel and at their lower end to an previously installed underwater structure.
  • the system is relatively complicated and costly because, among other things, it involves the use of braking devices with controllable and adjustable operation, requiring a complicated mechanical/hydraulic control system.
  • the object of the present invention is to provide a method and a device permitting the simple and inexpensive launch, sinking, positioning and orientation of a structure or of a protective cover over a structure which it is desired to protect on the sea floor.
  • a further object of the invention is to provide a rapid lowering procedure followed by a speedy and practical positioning and orientation method, such that the sinking and positioning can be carried out in a safe and rapid manner without unnecessary loss of time or unnecessary extra cost. It is furthermore an object of the invention to achieve this result with the aid of simple, inexpensive and reliable equipment.
  • the method can be implemented for an ordinary supply ship without a crane .
  • the launch takes place by sliding the structure, e.g. the cover, over the stern or side of the vessel.
  • the sinking procedure results in the rapid lowering of objects from the surface to the sea floor without unnecessary control means, yet such that the object stops at a desired position, after which the remainder of the descent can be executed in a much more exact and precise manner so that the object engages with fixing means positioned in advance under water.
  • Fig. 1 shows an example of how the launch can take place
  • Fig. 2 shows a protective structure after it has been lowered towards the sea floor and is located directly above an underwater installation which it is desired to protect
  • Figs 3-6 show different steps in the process of the exact positioning, orienting and fitting of the protective structure
  • Fig. 7 shows the protective structure after fitting onto the underwater installation. Attention is drawn to the fact that the same reference numbers are used for the same components in all the drawings, that unnecessary details have been omitted to avoid clutter, and that the elements shown in the drawings are not necessarily drawn to the same scale.
  • a plurality of protective structures 1, as indicated in Fig. 1, are transported to the appropriate point on the sea surface by a suitable vessel 20, and a guide line 3 is passed through the structures 1.
  • the protective structure 1 can be launched from the vessel onto the surface by several methods. Normally it will be preferred that the guide line 3 will be passed through a purpose-made opening 5 in the structure 1 while the guide line 3 is slack and the protective structure 1 is on the vessel's deck, after which the structure 1 is launched onto the surface, possibly over a bulge or fender fitted to the vessel.
  • Fig. 2 shows a protective structure 1 after it has sunk quite quickly, by the action of gravity only, down the guide line 3 and has been stopped at a suitable distance above the underwater installation 2, by butting against a stopping device 12 previously fitted to the guide line 3 at a suitable height above the underwater installation 2.
  • Other details apparent from Fig. 2 are an attaching means or attachment point 4 intended for the receiving and attachment of the lower end of the several guide lines 3 to the underwater installation 2 ; at least one opening 5 in the protective structure 1 to accommodate the several guide lines 3; additional steering lines 6 which, together with tensioning means 7, are attached to the protective structure
  • the underwater installation 2 may be mounted direct on the sea floor or on a wellhead or other underwater installation, depending on the application.
  • the tensioning means consists of an inflatable buoy 7 attached to the additional steering lines 6, which in turn pass over or through guiding means therefor (indicated but not numbered) .
  • the protective structure 1 is assumed to be open to the water on its underside so that the ROV can grasp the lower ends of the additional steering lines 6.
  • Fig. 3 illustrates a more advanced stage of the procedure.
  • the ROV has grasped the additional steering lines 6, drawn them down to the underwater installation 2, and attached them to suitable purpose-made attachment points 8, 9 previously disposed on the underwater installation.
  • the attachment points 8, 9 may for example take the form of hooks, in which case the steering line may be provided with suitable loops to fit the said hooks.
  • the ROV is moved up to the buoy 7 and pumps gas into it so as to impart to it a suitable positive buoyancy.
  • the ROV has then finished its present task and is therefore not indicated in Fig. 3.
  • the protective structure is suspended on the guide line 3 by means of the stopping means 12 disposed thereon, and is moreover held in the correct position and orientation by the additional steering lines 6, which are now under tension.
  • the tension on the guide line 3 can be reduced in order to lower the protective structure 1.
  • the underwater installation 2 may appropriately be fitted with suitable fixing bars 10, 11 or similar fixing means designed to engage with matching openings or complementarily shaped fixing means in or on the protective structure 1.
  • Fig. 4 shows that the protective structure 1 is beginning its descent towards the underwater installation 2, during which the tension on the guide line 3 is gradually reduced.
  • the steering lines 6 are not provided with stopping means and hence do not impede the said descent .
  • the tension on the guide line 3 has been so far reduced that the protective structure 1 has been completely lowered onto and into engagement with the underwater installation 2, and in Fig. 6 the gas has been released from the buoy 7 so that the additional steering lines 6 are also completely slack.
  • the ROV is used in the procedure both to ensure the correct positioning and orientation of the protective structure 1 and to release the gas from the buoy 7, after which it detaches both the guide line 3 and the additional steering lines 6 from the underwater installation 2.
  • the stopping means 12 may also be collapsed or detached, after which the guide line 3 and the steering lines 6, together with the tensioning means 7, can be raised to the surface .
  • Fig. 7 shows the end result of the procedure, namely, the underwater installation 2 with the protective structure 1 fixed in the correct position and the correct orientation thereon.
  • the procedure described above can be modified in many ways.
  • an ROV may be carried out by a diver; a plurality of guide lines 3 and a greater or smaller number of steering lines 6 may be utilised; the tensioning device which has hitherto been shown only in the form of an inflatable buoy 7 may be replaced with a winch located on the surface vessel or another vessel; and the fixing bars 10, 11 may be of an entirely different design than shown.
  • the stopping means 12 might be designed in many different ways, one of the simplest forms being a ball with an opening through which the guide line 3 passes, such that the friction between the guide line and the stop ball can be controlled or is preset to a value to ensure that it will arrest the protective structure 1 as the latter falls freely towards the sea floor, while being low enough that the guide line can be pulled through the ball by applying additional tension thereto.
  • Other more sophisticated solutions of the stopping means 12 can be conceived, e.g. such that the stopping means is inflatable or that it can be moved laterally to an area where it can pass through the protective structure 1, or the protective structure 1 may be provided with a slit or a door such that when said slit or door is opened, the stopping means 12 can pass through the opening.
  • the stop ball 12 may be permanently mounted on the guide line.
  • the tensioning means 7 may be of various forms provided only that it ensures that the steering lines 6 are tightened sufficiently to steer the structure into the correct position and orientation when the guide line 3 is slackened.
  • the material of the structure 1 may be freely chosen provided that said material is sturdy enough to withstand the expected stresses.
  • Plastics-based composites are mentioned above as suitable materials for protective structures, and other possibilities might be e.g. laminated and sandwich structures, which may also include steel structures.
  • the procedure may naturally be used for the sinking and positioning of all types of structures that are have to be accurately positioned on the sea floor, and not only for protective structures.

Landscapes

  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Geology (AREA)
  • Mining & Mineral Resources (AREA)
  • Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Artificial Fish Reefs (AREA)
  • Earth Drilling (AREA)

Abstract

L'invention concerne un procédé ainsi qu'un dispositif de lancement et d'immersion d'une structure (1), de positionnement et d'installation de celle-ci sur un autre équipement sous-marin. La structure (1) doit être fixée dans une position et une orientation correctes par rapport à l'équipement (2). On a fixé préalablement au moins une corde de guidage (3) sur l'équipement sous-marin (2), dans un dispositif de fixation (4) agencé à cet effet, et on a guidé cette corde dans des ouvertures (5) appropriées ménagées dans la structure (1), laquelle est conçue pour être abaissée le long de ladite corde (3) en direction de l'équipement sous-marin (2). Lorsque l'on exécute le procédé de l'invention, avant de procéder aux étapes de lancement et d'immersion, on dote la structure (1) d'au moins une autre corde de commande (6), pourvue à son tour de moyens tendeurs (7), et, après l'étape d'abaissement de la structure, on attache les extrémités de la (des) corde(s) de commande (6) à des points d'ancrage appropriés (8, 9) conçus sur l'équipement sous-marin (2), ce qui permet de commander les moyens de tension (7) afin de tendre les cordes de commande (6). Puis on guide la structure (1) le long des cordes de commande (6), vers le bas, on l'installe sur l'équipement sous-marin (2) et on la fixe dans une position et une orientation correctes par rapport à cet équipement, par exemple au moyen de poteaux de fixation (10, 11) préalablement installés.
PCT/NO1998/000060 1997-02-27 1998-02-25 Procede et dispositif d'agencement et d'installation d'une structure sur un fond marin WO1998040602A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9920435A GB2338739A (en) 1997-02-27 1998-02-25 A method and a means for arranging and installing a structure on the sea bed

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NO970873 1997-02-27
NO970873A NO305449B1 (no) 1997-02-27 1997-02-27 FremgangsmÕte og anordning for sj°setting, nedsenking, posisjonering og installering av beskyttelsesstruktur

Publications (1)

Publication Number Publication Date
WO1998040602A1 true WO1998040602A1 (fr) 1998-09-17

Family

ID=19900428

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NO1998/000060 WO1998040602A1 (fr) 1997-02-27 1998-02-25 Procede et dispositif d'agencement et d'installation d'une structure sur un fond marin

Country Status (4)

Country Link
DK (1) DK199901143A (fr)
GB (1) GB2338739A (fr)
NO (1) NO305449B1 (fr)
WO (1) WO1998040602A1 (fr)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3502143A (en) * 1968-05-29 1970-03-24 Shell Oil Co Marine riser support system
US3503442A (en) * 1968-07-31 1970-03-31 Shell Oil Co Marine conductor pipe connecting method
US3705623A (en) * 1970-06-17 1972-12-12 Shell Oil Co Offshore well equipment with pedestal conductor
US4258794A (en) * 1979-05-14 1981-03-31 Otis Engineering Corporation Underwater completion habitat

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3502143A (en) * 1968-05-29 1970-03-24 Shell Oil Co Marine riser support system
US3503442A (en) * 1968-07-31 1970-03-31 Shell Oil Co Marine conductor pipe connecting method
US3705623A (en) * 1970-06-17 1972-12-12 Shell Oil Co Offshore well equipment with pedestal conductor
US4258794A (en) * 1979-05-14 1981-03-31 Otis Engineering Corporation Underwater completion habitat

Also Published As

Publication number Publication date
NO970873L (no) 1998-08-28
NO970873D0 (no) 1997-02-27
GB2338739A (en) 1999-12-29
DK199901143A (da) 1999-08-20
GB9920435D0 (en) 1999-11-03
NO305449B1 (no) 1999-05-31

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