BW Pioneer,
Første FPSO i US Gulf of MexicoUtfordringer og løsninger
Oslo, 27. mai 2099
FPSO conversions / Inocean recent projects
Knock Nevis FSOMaersk, Qatar
4.200.000 bbls storageSpread mooring
Knock Allan FPSOCanadian Natural Resources,Gabon, West Africa
25.000 bopd oil capacity1.300.000 bbls storageSpread mooring
Knock Adoon FPSOAddax Petroleum, Nigeria,West of Africa
60.000 bopd oil capacity1.700.000 bbls storageSpread mooring
Aker Smart 1 FPSOReliance Industries Ltd. India
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MPF01 FPDSOPetrobras, Black Sea
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DeepProducer FPSO DPFPSOcean
380.000 bbls storageDP unit
BW Offshore / Inocean recent projects
Inocean SOW – Documentation deliverables
Reports for class review and approval :
• Design basis & design brief etc
• Ultimate (ULS) and Fatigue (FLS) structural design report
• Stability book; intact and damage stabililty
General drawings for class review and approval
• General arrangements drws
• LQ incl. haz.area / fire and safety plan
Main structural drawings for class review and approval
• Structural Drawings (Midship section etc
• Topside and supporting structure (process modules, flare tower etc.)
• Structural categories
Marine P&ID & D&ID system drawings for class review and approval
• Ship systems incl ballast & bilge, fire & deluge etc
Contract BWO & PAI (Petrobras America Inc)
• 3Q 2007 contract signed BWO & PAI
• First FPSO in GOM on US Side
• Start Operation January 2010
• Vessel shall be able to operate for at least 8years uninterrupted
Field; Cascade Chinook
BW Pioneer FPSO
• LOA 241m
• LPP 232 m
• BM 42 m
• DM 20,4 m
• Draft 13,9 m
RULES / REGULATIONS
LAW / RULESOuter Continental Shell Lands Act
USCG AuthoritiesHull / Structure
MMS AuthoritiesTopside (Hydrocarbon)
Classification SocietyDNV
Petrobras America Inc GTD(General Technical Description /
Requirements
Design Basis Vessel Conversion
Global strength: Wave loads basedon 20 years return period
Local strength: Wave loads basedon daily return period
North Atlantic environmentSimple formulae for wave bendingmoment (IACS prescriptiveformulae)
Tanker Rules FPSO Standard
Global strength: Wave loads based on 100years return period
Local strength: Wave loads based on dailyreturn period
Designed for specified geographical area.Direct calculation of wave loads
KEY Challenges for BW Pioneer
• ULS (Ultimate Limit State for Hull and Deck Modules & Equipment)
• FLS (Fatigue Limit State for Hull)
• ALS (Accidental Limit State for Hull)
• Marpol Damage Hull
ULS (Ultimate Limit State) for hull
Operational mode – connected to STP bouy
• Vessel shall be able to remain connected to STP buoy for conditions upto and including a 100-year winter storm (Hs = 7.3m)
• Presence of eddy current means beam seas can not be excluded, i.e.headings ranging from head seas to beam seas
Disconnect case – Sail away from impending hurricanes
• Sailing ship – rules for ships may apply (ww or local wave climate?)
(headings 0 – 360 degrees for design loads)
ULS - Green water on deck
Issues:• Low freeboard at full draught• Non-colinear wind/waves/current
Motion & Model test:• Revealed green sea to be a concern
Schematic of selected model test run
ULS (cont.)
Possibility of beam seas leads to large transverse and vertical accelerations
Transverse accelerations ULS [m/s2]
Location Head sea± 30º
Head sea± 90º
Flare tower 3.8 7.6
Deck module 2.4 4.9
Helideck 2.3 5.8
Topside design – integrated analysis
Large accelerations (similar magnitude as North Sea) required integrated analysis
Topside design
GTD requirement for z-quality for all structure in laminar tension
FLS Methodology
Trading tanker / consumed fatigue life
• Inspection of vessel
• Mapping of historic damages
• Basis for selection of consumed fatigue assessment methods
(Nauticus Hull Fatigue vs Stochastic Fatigue)
Historic trade and damage assessed by Nauticus Hull Fatigue
• Fatigue calculations for typical ballast and full load conditions based onprevious sailing history
• Different operational environments included by scaling of fe-factor (refDnV 30.7) Period Sailing route
1992 to 1994 Caribbean – US Gulf1995 - 1996 Far East – Australia1997 – 1999 Caribbean – US Gulf2000 - 2003 Europe and Mediterranean2003 - 2004 Caribbean – US Gulf
2004 - 2004 Europe2004 - 2007 Caribbean – US Gulf2009 - Permanently located as FPSO at Walker
Ridge location
FLS Methodology – Future fatigue damage FPSO
Requirements from client GTD
Specified heading profile
25% head seas
50% quartering seas
25% beam seas
Normal Requirements
Specified heading profile
head sea +/- 30 deg
FLS FEM – global structure and local SCF
Local SCF model
Full stochastic FLS is time consuming
Finite element modelling
• 14 local SCF models at side longitudinals
• 2 of stringer connetions
• 1 on hopper connection
Large amount of data
• 2.5 Tera Byte with analytical data (2500 Gbyte)
• 64b Finite Element solver (Sestra ) - custom setup from DnV for Inocean
1 year calculation periode
FLS summary
• Conversion projects differ from newbuilding since structure already hasdemonstrated its actual fatigue performance (trading as tanker)
• Identification of critical details - with high confidence level
• Required design fatigue life as FPSO is 16 years included DFF of minimum 2on all details
• Details of stiffeners connection to bhd was improved in waterline area
• Relatively long design life as FPSO, with limited possibilites of repair,necessitate thorough fatigue analysis
ALS – Accidental Limit State
Additional concerns that must be designed for (ALS cases) :
• Sudden hurricanes – vessel unable to escape hurricane
• Loss of heading control or power while escaping hurricane
• Probability of occurrence to be less than 10-4
MARPOL REGULATIONS / DAMAGE HULL
Side damageLong. Extent: The smaller of or 14.5 m (Here 12.5 m)Transv. Extent: The smaller of or 11.5 m (Here 8.40 m)Vert. extent: From base line with no limit
MARPOL REGULATIONS / DAMAGE HULL
Raking bottom damageLong. extent: 0.6 L from the FP (Here 138 m)Transv. extent: B/3 anywhere (Here 14 m)Vert. extent: Breach of the outer hull
PAI Requirements
Side shell structure, in supply vessel mooring area, shall be
checked to ensure that the hull integrity will not becompromised due to vessel boat operations. The loads to beconsidered are those imposed by a 5.000 dwt supply vessel