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WO2012130281A1 - Plateforme semi-submersible - Google Patents

Plateforme semi-submersible Download PDF

Info

Publication number
WO2012130281A1
WO2012130281A1 PCT/EP2011/054800 EP2011054800W WO2012130281A1 WO 2012130281 A1 WO2012130281 A1 WO 2012130281A1 EP 2011054800 W EP2011054800 W EP 2011054800W WO 2012130281 A1 WO2012130281 A1 WO 2012130281A1
Authority
WO
WIPO (PCT)
Prior art keywords
pontoon
supports
semisubmersible
platform
support
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.)
Ceased
Application number
PCT/EP2011/054800
Other languages
English (en)
Inventor
Lars Geir BJØRHEIM
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.)
Equinor Energy AS
Original Assignee
Statoil Petroleum ASA
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 Statoil Petroleum ASA filed Critical Statoil Petroleum ASA
Priority to PCT/EP2011/054800 priority Critical patent/WO2012130281A1/fr
Publication of WO2012130281A1 publication Critical patent/WO2012130281A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
    • B63B1/02—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement
    • B63B1/10—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with multiple hulls
    • B63B1/107—Semi-submersibles; Small waterline area multiple hull vessels and the like, e.g. SWATH
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B39/00—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude
    • B63B39/02—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude to decrease vessel movements by displacement of masses
    • B63B39/03—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude to decrease vessel movements by displacement of masses by transferring liquids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B75/00—Building or assembling floating offshore structures, e.g. semi-submersible platforms, SPAR platforms or wind turbine platforms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
    • B63B1/02—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement
    • B63B1/10—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with multiple hulls
    • B63B1/12—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with multiple hulls the hulls being interconnected rigidly
    • B63B2001/128—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with multiple hulls the hulls being interconnected rigidly comprising underwater connectors between the hulls

Definitions

  • the invention relates to the field of semisubmersible platforms.
  • a semi-submersible platform 1 is provided with ballasted, watertight pontoons 2 located below the ocean surface and wave action.
  • the pontoons 2 provide buoyancy.
  • An operating deck 3 is attached to the pontoons using supports 4. The supports 4 allow the operating deck 3 to be located high above the sea level. As the pontoons 2 are located below the wave action, the operating deck 3 remains very stable and can be kept at a height well above that of any expected waves.
  • the pontoon 2 is anchored to the sea bed 5 using mooring lines that run through fairleads 6. This allows the platform to remain in the desired position and prevents it from drifting off.
  • the semi-submersible platform 1 is less affected by wave loadings than a normal ship. However, as the semisubmersible platform 1 has a small water-plane area, it is sensitive to load changes, and therefore must be carefully trimmed to maintain stability.
  • a typical semisubmersible platform has four pontoons 7, 8, 9, 10 forming a square, and four supports 1 1 , 12, 13, 14 extending between the pontoons and the operating deck.
  • Each support is located at a corner of a square formed by the pontoons and connects to the operating deck.
  • Each support has the same cross-sectional area, and each pontoon has the same cross-sectional area.
  • the topside centre of gravity (COG) of the semisubmersible platform is usually not in the centre of the square formed by the pontoons, but is located towards one side of the operating deck, towards the process area, as this is where the bulk of the weight of the operating deck is located.
  • the centre of buoyancy (COB) of the semisubmersible platform is located in the geometric centre of the platform.
  • the semisubmersible platform needs to be trimmed. This is achieved by using a greater volume of ballast water in the pontoon 10 furthest away from the COG than in the pontoon 8 closest to the COG in order to compensate for the offset COG. This technique is known, and is described in documents such as US 3,160,135 and US 4,538,939.
  • the pontoons are submerged at a greater depth than would otherwise be required for balancing the production area weight on the platform.
  • a lower displacement in the water means that the supports need to be longer. This is not optimal from cost and weight point of view, as there is a direct link between displacement and steel weight.
  • semisubmersible platforms can be used in several roles. They are often used for stable platforms for offshore drilling for hydrocarbons. However, semisubmersible platforms are also used to carry cranes for offshore construction, as offshore support vessels, and as offshore production platforms.
  • a semisubmersible platform is provided with an operating deck and a hull structure for supporting the operating deck.
  • the hull structure has a first end and an opposing second end, and comprises at least a first pontoon located substantially at the first end, and a second pontoon located substantially at the second end.
  • the first pontoon is connected to the operating deck by a first plurality of supports, and the second pontoon is connected to the operating deck by a second plurality of supports.
  • the first pontoon has a greater volume than the second pontoon, and at least one support of the first plurality of supports has a greater horizontal cross-section area than a corresponding support of the second plurality of supports.
  • the centre of gravity of the platform is located closer to the first end than the second end.
  • a pontoon located at the first end has a larger volume than a pontoon located at the second end, thereby ensuring that a centre of buoyancy of the semisubmersible platform is located closer to the first end than the second end.
  • An optional way to achieve the larger pontoon volume is to ensure that the pontoon located at the first end has a larger width than the pontoon located at the second end.
  • a support located at the first end optionally has a larger width than the support located at the second end.
  • At least one pontoon and one of its associated supports are supported by at least one common structural element. This ensures that loads are uniformly distributed.
  • the common structural element is used as a frame of the pontoon and a side shell of the support.
  • any of the first and second pontoons has a substantially rectangular cross-sectional area.
  • each support of any of the first and second plurality of supports has a substantially rectangular cross-sectional area.
  • the pontoons and/or the supports are substantially rectangular in cross- section, common structural elements can be used more easily.
  • the invention may be applied to any type of semisubmersible platform.
  • semisubmersible platforms include any of a production platform, a crane platform, an offshore support vessel, and an offshore production platform.
  • Figure 1 illustrates schematically a side view of a known semisubmersible platform
  • Figure 2 illustrates schematically a plan view of the pontoons and supports of a known semisubmersible platform
  • Figure 3 is a perspective view of pontoons and supports for a semisubmersible platform according to an embodiment of the invention
  • Figure 4 illustrates schematically a side view of a semisubmersible platform according to an embodiment of the invention
  • Figure 5 illustrates schematically a plan view of the pontoons and supports of a semisubmersible platform according to an embodiment of the invention.
  • FIG. 3 there are shown four pontoons 15, 16, 17, 18 and four supports 19, 20, 21 , 22.
  • the pontoons are submerged below the surface of water and the supports connect the pontoons to an operating deck (not shown).
  • the side of the platform at which pontoon 18 is located is referred to as the first side
  • the side of the platform at which pontoon 15 is located is referred to as the second side.
  • the pontoon 18 and the supports 21 , 21 at the first side have a greater volume than the corresponding pontoon 15 and supports 19, 20 at the second side. This is because the pontoon 18 at the first side is substantially wider than the pontoon 15 at the second side.
  • the width of the pontoon 18 at the first side is denoted D in Figure 3.
  • the supports 21 , 22 at the first side are substantially wider than the supports 19, 20 at the second side (again, denoted by D), and so the supports at the first side have a greater volume than the supports at the second side.
  • the drawing shows the supports and pontoons as being rectangular, but it will be appreciated that they could be of any suitable shape, such as oval, substantially circular and so on.
  • FIG 4 there is illustrated a side view of the platform 23.
  • the platform has an operating deck 24, on which the first end 25 and the second end 26 are shown. Pontoons 15 and 16 are shown, along with supports 19 and 21 .
  • the centre of gravity owing to the weight distribution of the operating deck, is located towards the first side, as described above with known semisubmersible platforms.
  • the pontoons 15, 18 and supports 19, 21 are ballasted, the centre of buoyancy is also located towards the first side, unlike known semisubmersible platforms. This is because the buoyancy of pontoon 18 and supports 21 , 22 is greater than the buoyancy of pontoon 15 and supports 19, 20 when they are equally ballasted. This ensures that the centre of buoyancy moves towards the first side.
  • Figure 5 shows a plan view of the pontoon and supports.
  • the supports 19, 20, 21 , 22 are rectangular or square.
  • the supports 21 , 22 on the first side 25 have a larger cross-sectional area than the supports on the second side 26.
  • pontoon 18 has a greater volume than pontoon 15 owing to having a greater width.
  • Moving the centre of buoyancy towards the centre of gravity by altering the size of the pontoon and supports means that the larger pontoons have more buoyancy without ballast, and so the pontoons and supports do not need to be ballasted individually.
  • This is in contrast to known semisubmersible platforms, in which the pontoons and supports must be carefully ballasted to compensate for the difference between the centre of gravity and the centre of buoyancy.
  • This has the advantage that the pontoons need not be displaced as deeply underwater, which reduces material costs of a semisubmersible platform.
  • the semisubmersible platform with rectangular columns and matching pontoons enables more optimal hull design by moving the centre of buoyancy (COB) towards the centre of gravity, without compromising the structural strength and stress flow, as corresponding pontoon and column side-shells are located in the same planes and have structural backing in the nodes. Nodes are the connections between pontoons and columns. Furthermore, moving the centre of buoyancy by altering the dimensions of the pontoons and supports, rather than individually ballasting them, ensures that the structural strength and stress flows in the platform are not compromised.
  • COB centre of buoyancy
  • support 21 is rectangular and has one cross-section dimension D that corresponds with the width of pontoon 18, and the other cross-sections dimension d as pontoon 17.
  • Support element 18a is part of a framework that provides support to both pontoon 18 and support 21.
  • support element 18a also provides support for pontoon 17.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Ocean & Marine Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Architecture (AREA)
  • Structural Engineering (AREA)
  • Bridges Or Land Bridges (AREA)

Abstract

L'invention concerne une plateforme semi-submersible (23) équipée d'un pont d'exploitation (24) et d'une structure de coque pour soutenir le pont d'exploitation. La structure de coque comporte une première extrémité (25) et une seconde extrémité (26) opposée et comprend au moins un premier ponton (18) situé sensiblement au niveau de la première extrémité et un second ponton (15) situé sensiblement au niveau de la seconde extrémité. Le premier ponton est rattaché au pont d'exploitation par une première pluralité de supports et le second ponton est rattaché au pont d'exploitation par une seconde pluralité de supports. Le premier ponton a un plus grand volume que le second ponton et au moins un support (21) de la première pluralité de supports a une plus grande superficie de section transversale horizontale que le support correspondant (19) de la seconde pluralité de supports.
PCT/EP2011/054800 2011-03-29 2011-03-29 Plateforme semi-submersible Ceased WO2012130281A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/EP2011/054800 WO2012130281A1 (fr) 2011-03-29 2011-03-29 Plateforme semi-submersible

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2011/054800 WO2012130281A1 (fr) 2011-03-29 2011-03-29 Plateforme semi-submersible

Publications (1)

Publication Number Publication Date
WO2012130281A1 true WO2012130281A1 (fr) 2012-10-04

Family

ID=44625702

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2011/054800 Ceased WO2012130281A1 (fr) 2011-03-29 2011-03-29 Plateforme semi-submersible

Country Status (1)

Country Link
WO (1) WO2012130281A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2576792A1 (es) * 2015-01-09 2016-07-11 Antonio Luis GARCÍA FERRÁNDEZ Forma del casco de una plataforma asimétrica flotante, para zonas marinas de cualquier profundidad

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3160135A (en) 1961-06-22 1964-12-08 Shell Oil Co Stabilizing system for floating platform
US4538939A (en) 1984-02-17 1985-09-03 Transworld Drilling Company Method for ballasting a vessel
GB2306137A (en) * 1995-10-10 1997-04-30 Mp Seaways Ss Ltd Storage of Liquid Hydrocarbons
US20050058513A1 (en) * 2003-06-04 2005-03-17 Nils Martensson Semi-submersible offshore vessel
WO2009102269A1 (fr) * 2008-02-14 2009-08-20 Gva Consultants Ab Corps de plateforme semi-submersible pour supporter le forage, le stockage, le traitement ou la production d’hydrocarbures en mer

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3160135A (en) 1961-06-22 1964-12-08 Shell Oil Co Stabilizing system for floating platform
US4538939A (en) 1984-02-17 1985-09-03 Transworld Drilling Company Method for ballasting a vessel
GB2306137A (en) * 1995-10-10 1997-04-30 Mp Seaways Ss Ltd Storage of Liquid Hydrocarbons
US20050058513A1 (en) * 2003-06-04 2005-03-17 Nils Martensson Semi-submersible offshore vessel
WO2009102269A1 (fr) * 2008-02-14 2009-08-20 Gva Consultants Ab Corps de plateforme semi-submersible pour supporter le forage, le stockage, le traitement ou la production d’hydrocarbures en mer

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
ES2576792A1 (es) * 2015-01-09 2016-07-11 Antonio Luis GARCÍA FERRÁNDEZ Forma del casco de una plataforma asimétrica flotante, para zonas marinas de cualquier profundidad

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