Upload
rodhibakar
View
232
Download
1
Embed Size (px)
Citation preview
7/31/2019 SNAME 8 Jan 2008
1/25
FLOAT-OVERS: WHATS PRESENT AND
WHATS NEXT
7/31/2019 SNAME 8 Jan 2008
2/25
Agenda
Float-overs: An introduction
Present status of Float-over technology
Whats next for Dockwise?
Conclusions
7/31/2019 SNAME 8 Jan 2008
3/25
Recent changes
Jan 2007: Sold by Heerema to 3i
April 2007: Merged with Sealift Ltd. (6 new vessels)
July 2007: Acquisition of OKI/ODL
Oct 2007: IPO on Oslo Stock Exchange
7/31/2019 SNAME 8 Jan 2008
4/25
The Dockwise business
7/31/2019 SNAME 8 Jan 2008
5/25
The ODL Business
OffshoreFloatoverInstallation
DeepwaterFixedStructure
FloatingSystemDesign
Deepwater jacket structure
Compliant piled tower
Conventional jacket and deck
Conventional single barge floatover
Twin barge floatover
Floatover on jacket and floater
Global performance and sizing
Stability, motion, mooring and riser
Global and local structure, 2nd steel
7/31/2019 SNAME 8 Jan 2008
6/25
The ODL Resources
Houston Head Office
13 full time employees Highly educated and experienced
employees include 6 professionalengineers, 6 Ph.D.s
China Office, Shenzhen
19 full time employees 9 master degreed engineers
ODL Expertise
Specializes in analysis and design of offshore installation, offshore structures(fixed and floating), mooring system and riser systems
7/31/2019 SNAME 8 Jan 2008
7/25
Float over principleFixed substructure
East Area GN Deckon HTV Black Marlin
Operator:ExxonMobil
Weight: ~18000 mT
Location: Offshore
Nigeria
I
7/31/2019 SNAME 8 Jan 2008
8/25
Float over principlesemi submersible
Statoil Kristin FPU
Contractor:
AkerKvaerner
Weight: ~19000 mT
Location: inshore
Norway
I
7/31/2019 SNAME 8 Jan 2008
9/25
Float over principleSpar
Murphy Kikeh Spar
Contractor: Technip
Weight: ~4000 mT
Location: Offshore
Malaysia
I
7/31/2019 SNAME 8 Jan 2008
10/25
SafeFast
Cost effective
Efficient
WHY?
7/31/2019 SNAME 8 Jan 2008
11/25
Float-over Sequenceload-outCritical Factors in a Loadout Operation:
Vessel pumping capacity;
Vessel strength/skid beam design;
Pulling jack capacity and reliability;
Integrated deck weight and skidding friction;
Tidal range;
Quayside dimensions.
7/31/2019 SNAME 8 Jan 2008
12/25
Float-over Sequencesea transportationCritical factors during sea transportation:
Vessel stability vs. deck weight/CG height;
Global strength of vessel;
Local strength of vessel;
Sea fastening arrangement vs. motion inducedforces.
12.000 tons@
18.00 m
60.000 tons@
37.00 m
63.00 m 42.00 m
7/31/2019 SNAME 8 Jan 2008
13/25
Float-over SequencedockingCritical factors during docking operation:
Heading control of the vessel; Transverse control of the vessel w/ away
fenders and cross lines;
Longitudinal control of the vessel with mooringlines and cross lines;
Control impact loads on jacket w/sway fenders; Maintain vertical clearances during entry and
withdrawal operations.
7/31/2019 SNAME 8 Jan 2008
14/25
Float-over Sequencemating: non-swell environmentsCritical factors during mating operation
Limit horizontal excursion circle prior to lowering operation through fenders & cross lines:
Minimize vertical impact loads between jacket & deck legs through installed LMUs; Minimize vertical impact loads between deck legs and vessel deck through DSUs;
Achieve load transfer from vessel to jacket legs through vessel ballasting;
Continue vessel ballasting until sufficient vertical clearances for withdrawal operation.
7/31/2019 SNAME 8 Jan 2008
15/25
Float-over Sequencemating: swell environmentsCritical factors during mating operation
Limit stabbing cone horizontal excursion within designed circle by an anti-surge system;
Minimize vertical impact loads between jacket & deck legs through hydraulic cylinders and LMUs; Minimize vertical impact loads between deck legs and vessel deck through quick separation system(hydraulic cylinders) and DSUs;
Achieve load transfer from vessel to jacket legs through vessel ballasting and cylinderextension/retraction;
Combined vessel ballasting and cylinder retraction for vertical clearances prior to exit operation.
7/31/2019 SNAME 8 Jan 2008
16/25
0
5000
10000
15000
20000
25000
30000
35000
40000
1990 1992 1994 1996 1998 2000 2002 2004 2006 2008
Year
Deckweight
[st]
Whats presentintegrated deck weights and number of installed decks
7/31/2019 SNAME 8 Jan 2008
17/25
Whats presentpassive float-over methods Load transfer only by vessel ballasting;
Moderate to mild wave climate w/o swells;
Sufficient draft fluctuation of the vessel to suit requirement; Utilization of LMUs and DSUs to reduce impact loads;
Capacity >21000 tons.
Full load onDSUs
0% Load
Partial load on
DSUs
Partial load onLMUs
0% Load
Full load w/Steel-to-Steel
contacts
BallastBallast Ballast
7/31/2019 SNAME 8 Jan 2008
18/25
Whats presentactive float-over methods Active lowering system w/ cylinders integrated with deck supports;
Applications in swell environments during installation seasons (5 of 12months in West Africa environments);
Require an anti-surge system to reduce excursion circle;
Draft fluctuation insufficient to create gaps for entrance/exit clearances;
Quick separation system is required to obtain vertical exit clearances;
Capacity 18.000 tons or less so far.
7/31/2019 SNAME 8 Jan 2008
19/25
Whats present?pontoon barge method
No slot required for fixed jackets;
Suitable for SPAR buoys;
Require a transfer operation prior toinstallation;
Not suitable for long distance sea voyage
under pontoon barge configuration;
One successful installation for fixed jacketby ODL for Corocoro WHP project;
One successful installation for Kikeh Sparproject by Technip.
7/31/2019 SNAME 8 Jan 2008
20/25
Whats next for Dockwise?Strengthen R&D Efforts and Improve Market Position
Combined efforts through Dockwise, ODL and OKI;
Introduce Friction Fender concept for harsh swell conditionapplications w/o hydraulic cylinders;
Improve Pontoon Barge Method w/o a transfer operation;
Introduce Outrigger method to improve vessel stability for highCG and heavy decks.
7/31/2019 SNAME 8 Jan 2008
21/25
Whats next?friction fender concept for WA applications Objectives:
Utilize friction to reduce vessel heave motions;Eliminate hydraulic cylinders to improve system reliability;
Suitable for floating and fixed platform topsides installations;
Increase installation season in WA from current 5 months to 12 months long.
Concept confirmed in studies and a model test is planned in 2008;
Software development is required for the system calculations.
7/31/2019 SNAME 8 Jan 2008
22/25
Whats next?improve pontoon barge method Loadout directly onto two pontoon barges at fabrication yard;
Purposely built pontoon barges; Suitable for transportation under harsh environments;
Suitable for both fixed and floating platforms;
Joint study with CNOOC is underway.
7/31/2019 SNAME 8 Jan 2008
23/25
Whats next?outrigger concept For high CG heavy decks, stability, not displacement, is the big challenge;
Increase stability by adding removable sponsons far away from vessel CL; Whole system, sponsons plus truss, is independently maneuvered and transported;
Increase transport speed by adding self-propulsion systems to the sponsons;
Suitable for transverse loadout;
Internal development is underway.
7/31/2019 SNAME 8 Jan 2008
24/25
Conclusions
Float-over is a mature installation method;
Float-over is a competitive alternative for:
Integrated decks beyond crane vessel capacity;
Integrated decks to be installed in remote areas;
Less environmentally sensitive than lifting option.
Improvements to be expected in the fields of:
Workability and system reliability under swell environments;
Installation capacity for heavy and high CG topsides;
Alternative float-over system such as pontoon barge method.
7/31/2019 SNAME 8 Jan 2008
25/25
Jan Wolter OosterhuisDockwise USA LLC
James Lee
Ocean Dynamics, [email protected]