WO2008024527A2 - Système d'ancrage à tension inverse - Google Patents

Système d'ancrage à tension inverse Download PDF

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Publication number
WO2008024527A2
WO2008024527A2 PCT/US2007/061824 US2007061824W WO2008024527A2 WO 2008024527 A2 WO2008024527 A2 WO 2008024527A2 US 2007061824 W US2007061824 W US 2007061824W WO 2008024527 A2 WO2008024527 A2 WO 2008024527A2
Authority
WO
WIPO (PCT)
Prior art keywords
chain
mooring
anchor
forerunner
floating structure
Prior art date
Application number
PCT/US2007/061824
Other languages
English (en)
Other versions
WO2008024527A3 (fr
Inventor
John Mathew Riggs
Original Assignee
Intermoor, Inc.
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 Intermoor, Inc. filed Critical Intermoor, Inc.
Publication of WO2008024527A2 publication Critical patent/WO2008024527A2/fr
Publication of WO2008024527A3 publication Critical patent/WO2008024527A3/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

Definitions

  • This invention relates generally to systems for mooring floating structures, and more particularly to a mooring system which eliminates the requirement for providing tensioning mechanisms on floating structures to be moored, and in lieu thereof utilizes tensioning mechanisms mounted on one or more anchor handling vessels to apply mooring tension.
  • floating structures such as drilling rigs, production rigs, CALM buoys, SPARs, FPSOs, FSOs, etc. have been moored to an anchor system that is put under operating tension by tensioning equipment on the floating structure.
  • the mooring tensioning equipment usually contains winches, fairleads, chain lockers, presets, and excess wire reels.
  • the anchors When the floating structure is brought onto location, the anchors are run out, or alternatively, the preset mooring lines are connected to the anchors (the so called preset anchor system) .
  • the floating structure is connected to the anchors, by either method, the mooring legs are tensioned to the design specifications and the structure is secured at the desired location.
  • tensioning is done at the structure for large floating structures.
  • the tensioning is done by temporary winches or cranes. The concept is the same; the tensioning is done at the floating structure.
  • the mooring padeye is commonly located two-thirds of the way down the side of the anchor.
  • the suction anchor is preinstalled and the anchor forerunner chain is attached to the mooring padeye.
  • the end of the forerunner chain is run out and extends to a subsea connector which is typically positioned on the sea floor.
  • the mooring line is connected to the subsea connector and the mooring leg is tensioned by tensioning equipment on the floating structure.
  • Plate anchors, driven piles, and other vertically loaded anchors have the same arrangement and means of tensioning.
  • the mooring system of the present invention differs in that tensioning is done at the anchors with the aid of tensioning equipment on an anchor handling vessel. There is no need for any tensioning equipment on the floating structure.
  • the mooring line is connected to the floating structure by means of a simple, fixed padeye or similar appurtenance. No winches, fairleads, etc. are needed on the floating structure.
  • the padeye is replaced with a turning shoe or chain whelp.
  • a stopper mechanism such that the chain can pass in one direction only (away from the floating structure) is incorporated. If the anchor has a portion of its structure above the mudline the stopper may be located at the top of the anchor. For completely embedded anchors the stopper may be incorporated into the turning shoe or whelp.
  • the stopper mechanism has a release line or mechanism such that the mooring line tension can be released, if necessary.
  • the forerunner chain is run through the turning shoe or whelp and back to the surface, either on top of the pile or suction anchor, or on the sea floor for plate anchors or vertically loaded anchors.
  • the subsea connector arrangement is the same as with conventionally tensioned mooring systems.
  • FIGURE 1 is an illustration of a prior art mooring system
  • FIGURE 2 is an illustration of an initial step in a method of mooring floating structures comprising a first embodiment of the invention
  • FIG. 3A is an illustration of a somewhat later step in the method of mooring floating structures comprising the first embodiment of the invention
  • FIGURE 3B is an illustration of a still later step in the method of mooring floating structures comprising the first embodiment of the invention
  • FIGURE 3C is an illustration of a still later step in the method of mooring floating structures comprising the first embodiment of the invention wherein a tensioning device on an anchor handling vessel is connected to a mooring line extending to a floating structure ;
  • FIGURE 3D is an illustration of a still later step in the method of mooring floating structures comprising the first embodiment of the invention wherein the tensioning device of the anchor handling vessel is utilized to apply mooring tension to the mooring line extending to the floating structure;
  • FIGURE 4A is an illustration of an initial step in a method of mooring floating structures comprising a second embodiment of the invention.
  • FIGURE 4B is an illustration of a later step in the method of mooring floating structures comprising the second embodiment of the invention.
  • FIG. 1 a conventional floating structure 10.
  • the floating structure 10 may comprise a drilling rig, a production rig, a CALM buoy, a SPAR, an FPSO, an FSO, etc.
  • larger floating structure are typically provided with a plurality of permanently installed tensioning devices 12 such as winches or the like.
  • tensioning mechanisms may be temporarily installed thereon for use during the mooring process .
  • the tensioning devices are utilized to apply mooring tension to a plurality of mooring lines 14 which extend from the floating structure 10 to a plurality of anchors 16 each individual to one of the mooring lines 14.
  • the anchor 16 illustrated in Figure 1 is a suction pile of the type shown and described in U.S. Patent No. 6,009,825 the disclosure of which is incorporated herein by reference.
  • the mooring system of Figure 1 can also be utilized in conjunction with other anchor types such as plate anchors, driven piles, vertically loaded anchors, etc., all of which are well known in the art.
  • the method of mooring floating structures of Figure 1 begins with the installation of a plurality of anchors at spaced apart locations around a mooring location.
  • a forerunner chain connected thereto is extended along the sea floor in the general direction of the mooring location.
  • the floating structure 10 is moved to the mooring location and the mooring lines 16 thereof are connected to the forerunner chains extending from the previously installed anchors 16.
  • the tensioning mechanisms 12 mounted on the floating structure 10 are employed to apply mooring tension to the mooring lines 14.
  • the tensioning mechanisms 12 mounted on the floating structure 10 serve no further purpose unless and until the floating structure 10 is repositioned or relocated.
  • FIGs 2, 3A, 3B, 3C, and 3D illustrate a method of mooring floating structures comprising a first embodiment of the present invention.
  • an otherwise conventional suction anchor 20 is lowered into engagement with the sea floor by a line 22 extending from an anchor handling vessel.
  • the suction anchor 20 is provided with a chain receiving device 24 which may comprise a turning shoe, a chain whelp, etc.
  • a chain 26 extends around the device 24.
  • One end of the chain is secured to the suction anchor 20 by a chain stopper 28.
  • the opposite end of the chain includes a subsea connector 30 which is initially connected to the anchor handling vessel by a line 32.
  • the suction anchor 22 initially penetrates the uppermost layers of the sea floor under its own weight. Thereafter a pumpskid 40 is engaged with the suction anchor 20.
  • the pumpskid 40 is preferably of the type illustrated and described in U.S. Patent No. 5,927,904 the disclosure of which is incorporated herein by reference.
  • the function of the pumpskid 40 is to pump water out of the interior of the suction anchor 20 whereby the suction anchor 20 is driven downwardly into the sea floor under the action of the pressure that is imposed upon the suction anchor 20 by the sea. Operation of the pumpskid 40 and downward movement of the suction anchor 20 into the sea floor continue until only the uppermost portion of the suction anchor 20 remains exposed above the upper surface of the sea floor .
  • the suction anchor 20 is shown fully installed in the sea floor.
  • the forerunner chain 26 extends upwardly from the device 24, and then along the surface of the sea floor to the subsea connector 30.
  • An anchor handling vessel 42 connects a mooring line 44 to a floating structure 46 in the conventional manner.
  • the floating structure 46 may comprise many of a wide variety of floating structures such as a drilling rig, a production rig, a CALM buoy, a SPAR, an FPSO, an FSO, etc.
  • the floating structure 46 is identical to the floating structure 10 of Figure 1 except that the floating structure 46 is not equipped with conventional mooring tensioning equipment .
  • the mooring line 44 is initially secured to the anchor handling vessel 42 by a line 48.
  • the mooring line 44 extends to a subsea connector 50 adapted for mating engagement with the subsea connector 30.
  • a remotely operated vehicle (ROV) 52 operatively secured to the anchor handling vessel 42 is employed to connect the subsea connector 50 to the subsea connector 30, and to confirm that the connection has been properly made. After the subsea connectors 30 and 50 are joined one to another, the ROV 52 disengages the line 48 from the mooring line 44.
  • ROV remotely operated vehicle
  • the ROV 52 After disengaging the line 48 from the mooring line 44, the ROV 52 connects the line 48 to the end of the chain 26 remote from the subsea connector 30 in the manner illustrated in Figure 3C.
  • the anchor handling vessel 42 applies an upwardly directed force to the line 48 in the manner indicated by the arrow 54 in Figure 3D. This causes the chain 26 to be pulled through the device 24 thereby applying mooring tension to the mooring line 44 and the floating structure 46.
  • the chain stopper 28 (Fig. 2) prevents the chain 26 from moving in the reverse direction through the device 24.
  • the chain stopper 28 is preferably constructed such that the chain 26 can be disengaged therefrom by the ROV 52 should it become necessary to release mooring tension from the line 44 and the floating structure 46 for any reason.
  • the final step in the method of mooring floating structures according to the first embodiment of the invention comprises utilization of the ROV 52 to disengage the line 48 from the chain 26 whereupon the line 48 and the ROV 52 are withdrawn onboard the anchor handling vessel 42.
  • Figures 4A and 4B illustrate a method of mooring floating structures comprising a second embodiment of the invention.
  • Many of the component parts utilized in the practice of the second embodiment of the invention are substantially identical in construction and function to component parts utilized in the practice of the first embodiment of the invention and described hereinabove in conjunction therewith.
  • Such identical component parts are designated in Figures 4A and 4B with the same reference numerals utilized in the foregoing description of the first embodiment of the invention but are differentiated therefrom by a prime ( ⁇ ) designation.
  • the suction pile 20' does not, in and of itself, serve as an anchor. Rather, the suction pile 20' serves as an installation device for a plate anchor 60.
  • the construction of the plate anchor 60 and the utilization of the suction pile 20' to effect installation thereof in the sea floor are fully described in U.S. Patent No. 6,122,847 issued September 26, 2000 the disclosure of which is incorporated herein by reference.
  • the plate anchor 60 is provided with a chain 26' .
  • one end of the chain 26' is secured to the suction pile 20 by a chain keeper 28A.
  • the opposite end of the chain 26' extends to a subsea connector 30' which is in turn connected to an anchor handling vessel by a line 32'.
  • the chain 26' extends through a device 62 which serves both as a turning shoe or chain whelp and as a chain stopper.
  • FIG. 4B illustrates the plate anchor 60 installed in the sea floor.
  • the plate anchor 60 may be provided with a recovery device 64. If used, the recovery the device 64 is deployed on the sea floor and is connected to the plate anchor 60 by lines 66. The purpose of the recovery device 64 is to allow the plate anchor 60 to be withdrawn from the sea floor and recovered to the surface for installation at a different location.
  • the chain 26' includes a first end 26'A which extends to a floating platform and a second end 26 'B which extends to a buoy 61.
  • a chain is connected between the anchor handling vessel and the end 26'B of the chain 26' that is secured to the buoy 61.
  • a tensioning mechanism on the anchor handling vessel draws the chain 26' through the device 62.
  • the chain stopper feature of the device 62 prevents the chain from passing through the device 62 in the opposite direction.
  • a line 68 extends to a release mechanism comprising the device 62 whereby the chain may be permitted to pass from the anchor handling vessel toward the floating platform if necessary.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Ocean & Marine Engineering (AREA)
  • Revetment (AREA)
  • Bridges Or Land Bridges (AREA)

Abstract

Selon cette technique d'ancrage pour structures flottantes, un dispositif récepteur de chaîne est fixé à une ancre et une chaîne d'amorce traverse ce dispositif après quoi l'ancre est engagée dans le fond marin. Une ligne d'ancrage va de la structure flottante à la chaîne d'amorce. Un dispositif tendeur ou un bateau commandant l'ancre applique une tension d'ancrage à la chaîne d'amorce et, partant, une tension d'ancrage à la ligne d'ancrage entre la chaîne d'amorce et la structure flottante. La tension d'ancrage est maintenu par le dispositif récepteur de chaîne sur l'ancre.
PCT/US2007/061824 2006-07-20 2007-02-08 Système d'ancrage à tension inverse WO2008024527A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US11/458,818 US20070017429A1 (en) 2005-07-21 2006-07-20 Reverse tensioned mooring system
US11/458,818 2006-07-20

Publications (2)

Publication Number Publication Date
WO2008024527A2 true WO2008024527A2 (fr) 2008-02-28
WO2008024527A3 WO2008024527A3 (fr) 2008-07-03

Family

ID=39107469

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2007/061824 WO2008024527A2 (fr) 2006-07-20 2007-02-08 Système d'ancrage à tension inverse

Country Status (2)

Country Link
US (1) US20070017429A1 (fr)
WO (1) WO2008024527A2 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101148033B1 (ko) * 2009-02-24 2012-05-24 대우조선해양 주식회사 리그의 항내 계류방법
WO2013043049A1 (fr) 2011-09-23 2013-03-28 Ihc Holland Ie B.V. Dispositif et procédé de tension de chaînes, en particulier des jambes d'amarrage

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU2003254482A1 (en) * 2002-07-23 2004-02-09 Philip Head Seabed installation apparatus
US9879396B2 (en) 2013-06-24 2018-01-30 Trendsetter Vulcan Offshore, Inc. Systems and methods for tethering subsea structure mounted on a wellhead
US9487272B2 (en) 2014-03-14 2016-11-08 Intermoor, Inc. Systems and methods for tensioning mooring lines at the seafloor
GB2551379B (en) * 2016-06-16 2018-12-12 Acergy France SAS Upgrading subsea foundations of mooring systems
WO2020041088A1 (fr) * 2018-08-21 2020-02-27 Exxonmobil Upstream Research Company Réduction de tranchée au niveau de lignes d'amarrage
WO2020176262A2 (fr) * 2019-02-13 2020-09-03 Jason Cotrell Ancres ventouses et leurs procédés de fabrication
FR3112754B1 (fr) * 2020-07-22 2022-10-14 Technip France Procéde de mise en place d’au moins une ligne d’ancrage d’une installation flottante dans une étendue d’eau et installation flottante associée

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6009825A (en) * 1997-10-09 2000-01-04 Aker Marine, Inc. Recoverable system for mooring mobile offshore drilling units
US6122847A (en) * 1997-11-17 2000-09-26 Aker Marine Contractors, Inc. Method of and apparatus for installation of plate anchors
US20020189522A1 (en) * 2001-06-15 2002-12-19 Dove Peter G. S. Method of and apparatus for offshore mooring

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5927904A (en) * 1997-10-29 1999-07-27 Aker Marine, Inc. Pumpskid for suction anchors

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6009825A (en) * 1997-10-09 2000-01-04 Aker Marine, Inc. Recoverable system for mooring mobile offshore drilling units
US6122847A (en) * 1997-11-17 2000-09-26 Aker Marine Contractors, Inc. Method of and apparatus for installation of plate anchors
US20020189522A1 (en) * 2001-06-15 2002-12-19 Dove Peter G. S. Method of and apparatus for offshore mooring

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101148033B1 (ko) * 2009-02-24 2012-05-24 대우조선해양 주식회사 리그의 항내 계류방법
WO2013043049A1 (fr) 2011-09-23 2013-03-28 Ihc Holland Ie B.V. Dispositif et procédé de tension de chaînes, en particulier des jambes d'amarrage
US9630681B2 (en) 2011-09-23 2017-04-25 Ihc Holland Ie B.V. Device for and method of tensioning chains, in particular mooring legs

Also Published As

Publication number Publication date
WO2008024527A3 (fr) 2008-07-03
US20070017429A1 (en) 2007-01-25

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