Tanker Conversions to FPSOs

Transcription

1 OGP Marine Risks Workshop Proceedings 9. Tanker Conversions to FPSOs Rob Potthurst, Lloyd s Register Presentation on Tanker Conversions to FPSOs Rob Potthurst Offshore Floating Units Oil and Gas Overview Market summary LR Experience Key issues Rules and Regulations Hull strength and fatigue Some lessons learnt (hopefully) 131

2 International Association of Oil & Gas Producers Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (2) FPSO / FSO Market Ship-type type Floating Production Units Newbuild (30%) Total 70+ units worldwide Conversion (70%) 132

3 OGP Marine Risks Workshop Proceedings Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (3) Future Floating Offshore Installation Projects SPAR (18%) TLP (11%) FSO (8%) Semi (3%) FPSO (60%) Analysis of asset types identified under the most likely development solution F(P)SO Capabilities Typical Requirements Storage 200,000-2,000,000 barrels Production 30, ,000 bopd Vessel 100, ,000 tonnes Water depth metres Topsides tonnes Risers 1 - > 30 Wave height benign - > 30 metres Air temp -20 o C - > 30 o C 133

4 International Association of Oil & Gas Producers Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (4) LR Experience LR Experience FPSO and FSO Units Steel Fixed Platforms ~ 800 Buoys Pipelines Jack-ups Semi-submersibles Concrete Structures ~ 40 ~ 15 ~ 70 ~ 50 ~ 75 ~

5 OGP Marine Risks Workshop Proceedings Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (5) Floating Production Installations - LR Worldwide Experience Canada 3 Mediterranea n 4 West of Shetlands Brazi l 3 1 North Sea 19 Australia 5 Vietna m Philippine Philippine 2 s 2 New Zealand 1 Recent Conversion Experience Amerada Hess Triton Amerada Hess Fife Amerada Hess Bluewater Durward/Dauntless Bluewater Bleo Holm Expro Efiat Abana MAS Curlew Petechim Vietsovpetro Dragon Petrobras Roncador Petrobras Barracuda (ex PP.Moraes) Reading & Bates Seallion Shell Todd Maui B SLP/Maersk Conoco MacCulloch Shell soreena 135

6 International Association of Oil & Gas Producers Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (6) Example of Conversion Conoco MacCulloch North Sea Producer - Teesside Example of Conversion FPSO Whakaaropai for Shell Todd Maui B Field Oil Storage Capacity approx. 760,000bbls 136

7 OGP Marine Risks Workshop Proceedings Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (7) Conversions Key Issues Overall requirements Shallow/Deepwater Turret/Spread mooring arrangements Permanent / Disconnectable moorings Small/Large displacement hulls Benign/Harsh environments Project management required 137

8 International Association of Oil & Gas Producers Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (8) What makes an FPSO different from a trading tanker? Operations and safety requirements Layout and arrangement Specified service/location Rules and regulations Design/construction/commissioning In-situ inspection/maintenance Key Choice Drivers Project and client requirements time to first oil location/environment function life cycle costs Statutory and National Authority requirements Ship Yard schedule availability / capability / price location Availability of suitable tonnage capacity condition, age upgrading scope New build: 2 to 3 years; Conversion: 1 to 2 years 138

9 OGP Marine Risks Workshop Proceedings Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (9) Hull Selection Issues (conversion) Vessel age, condition and service history hull global strength remaining corrosion margins remaining fatigue life structural steelwork replacement Mooring structure internal or external modifications structural reinforcement Topside integration structural reinforcement Upgrades equipment / systems coatings / corrosion control machinery accommodation Conversion - Major Works Existing Hull Removals/modifications hull steelwork, coatings etc. propulsion and other machinery rudder/steering gear accommodation, deckhouses and helideck piping systems Upgrades marine and topsides control system integration fire protection systems and their integration power generation systems and their integration cargo tank venting arrangement ballast and cargo oil pumps and valves inert gas system utility systems (eg( water, steam, heating) 139

10 International Association of Oil & Gas Producers Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (10) Conversion - Major Works Hull Additions turret or spread mooring system, equipment, etc riser porches or fluid transfer system and piping provision of thrusters installation of process deck supports process systems PAUs,, flare and piping blast walls life saving equipment fire and gas equipment and systems evacuation measures bulwark and breakwater lifting equipment loading instrument (computer) offloading system Mooring Arrangements Bow Mooring Internal Turret Mooring Spread Mooring 140

11 OGP Marine Risks Workshop Proceedings Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (11) Turret Mooring Systems Large Internal Turret Internal Small Internal Turret External Riser Turret Mooring (D) Buoyant Turret Mooring (D) Submerged Turret Production (D) External Turret Mooring General arrangement Living quarters Flare Tower Metering Metering P.G. Oil Sep. Gas Comp. Living quarters at the stern Oil Sep. Gas Comp. P.G. Living quarters at the bow Turret Flare Tower Turret Living quarters 141

12 International Association of Oil & Gas Producers Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (12) FPSO Rules and Regulations Governing Regulations Local National Authority Class Rules for FPSO Installations Flag State International Conventions SOLAS, MARPOL, LOADLINE, TONNAGE 142

13 OGP Marine Risks Workshop Proceedings Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (13) National Regulations U.K. HSE safety case and verification Canada(NS) CNOPB, TC(flag),RQF, class Brazil (BNW), class, flag Nigeria Marine Notice, class, flag(n) Gulf of Mexico Follows International Conventions SOLAS, MARPOL, LOADLINE, TONNAGE Definitions Class Rules Based / Risk Based Certification To Regulations and Codes Verification To Performance Criteria Class\Certification Certification\Verification often combined 143

14 International Association of Oil & Gas Producers Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (14) Rules for a Floating Offshore Installation at Fixed Location Rules Rules and and Rules Regulations and Rules and Rules Regulations Regulations and Rules Regulations and Regulations Rules and Part 4 Regulations Part Part 44 4 Part Part 4 5 Rules and Regulations Part 3 Part 2 Rules and Regulations Rules Part and 1A Regulations Part 1 Parts 2 to 9 Technical Regulations Part 1A Risk Based Approach Part 1 Regulations Scope of LR FPSO Rules LR Rules cover the following aspects : Hull and Marine Systems Mooring Systems Risers (optional) Process plant (optional) Drilling plant (optional) 144

15 OGP Marine Risks Workshop Proceedings Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (15) LR Classification Alternatives Prescriptive Rules - business as usual Flexibility of Risk Based options Risk Based Solutions Applicable to Design of both hull and topsides, although generally hull adopts prescriptive approach Applicable to Periodic Inspection (draft LR guidance available) LR Guidance Notes Supporting the Rules An Overview of Regulatory Issues Conversion of Tankers for Floating Production Service Ship Type Hull Structural Appraisal and supplement Additional Structural Aspects Positional Mooring Systems and supplement Fibre Ropes for Offshore Moorings Periodic Inspection Design Appraisal of Semi-Submersible Units AA6c 145

16 International Association of Oil & Gas Producers Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (16) Conversions Hull strength and fatigue Hull Design Considerations hull strength, arrangement and materials 100-year site specific criteria local connection details and fatigue life (min 20 years) range of loading conditions vessel motions and accelerations mooring system and hull integration process support structure slamming and green seas sloshing helideck, cranes and cargo offloading system accommodation corrosion control construction tolerances and fabrication quality philosophy for in-service periodic survey interfaces 146

17 OGP Marine Risks Workshop Proceedings Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (17) Model Testing - support To support design calculations Riser & mooring design Loading, excursions, separation FPSO/shuttle tanker interaction Hull motions, slamming, green seas Ship Rules - basic hull strength Parametric equations for : Wave bending moment/shear force inertia Hull modulus FEA requirement (strength/fatigue) Local strength WW service (limitation options) Equivalence through IACS 147

18 International Association of Oil & Gas Producers Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (18) FPSO Hull - Global Strength Minimum class rule standard Site specific environmental criteria Effect of mooring system (+weathervaning weathervaning) Process facilities Long term service (at site) Range of loading conditions (including inspection and accidental cases) Slamming/green seas FF2-1g 1g Global Hull Design wave BM & SF Still water loading conditions often more severe for FPSOs Class Rules permit review of Rule versus Site specific wave bending moments and shear forces Will depend upon site environmental criteria Harsh environment wave BM and SF are close to and may exceed Ship Rule requirements Benign environment are less than Ship Rules but not to be taken less than 70% of unrestricted service Ship Rule requirements in general Multisite operation may require assessment Owners requirements, eg corrosion margins Towing and temporary conditions to be considered 148

19 OGP Marine Risks Workshop Proceedings Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (19) 100 Year Hs / Tp Contours Hs1 2 i Hs2 2 i 12 Hs3 2 i TP1 TP2 TP3 2 i 2 i 2 i West of Shetland Northern North Sea Central North Sea Tp 30 Some typical criteria Hs Tp Nigeria Offshore Iran Australia U.K. Central West of Shetland Nova Scotia /18 149

20 International Association of Oil & Gas Producers Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (20) Accidental Loads Collision due to supply boat / shuttle tanker / iceberg Dropped object Explosion / blast Ultimate strength criteria Steel Grades Class rules for ships New requirements for low temperature operation Structural categories Thickness Location 150

21 OGP Marine Risks Workshop Proceedings Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (21) Hull Strength/Fatigue FEA Cargo / ballast tank area Hopper knuckle connection Mooring structure and hull integration Riser porches and supporting structure Topsides support structure and hull integration Flare tower support structure Access tower support structure Offloading station support structure Main crane pedestals and support structure Helideck structure Additional locations depending on vessel function and owners requirements Fatigue Life Factors of Safety Inspectable/ Repairable Yes, dry (see note 1) Yes, wet (see note 2) Fatigue Life Factor Consequence of Failure Non-substantial Substantial No 3 10 Substantial consequences of failure are defined as loss of life, uncontrolled outflow of hazardous products, collision or sinking and should include for progressive failure scenarios. Note 1 : includes external components which can be dry inspected / repaired. Note 2 : includes external components below the minimum operating draft which can only be inspected in water, but dry repairs could be carried out. 151

22 International Association of Oil & Gas Producers Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (22) Typical Critical Areas Process Supports Stress Concentration Misalignment Welding FPSO Fatigue Enhancement Details (conversion) Examples of modification to hull longitudinal connection details Additional lug Longitudinal/Transverse frame connection Additional bracket Shell plate Transverse frame Longitudinal Additional bracket Shell plate Transverse frame Longitudinal Exten Within cargo and ballast Item t Additional Lugs tanks Bottom and side shell (up to limit of wetted area) Additional Bkts Bilge area and side shell (up to limit of wetted area) Addition al bracket Shell plate Transverse frame Longitudinal 152

23 OGP Marine Risks Workshop Proceedings Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (23) Green Seas typ. 8-14m Rule requirements Model testing Pressures Breakwater Drainage Bottom Slamming 153

24 International Association of Oil & Gas Producers Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (24) Sloshing in Cargo Oil Tanks Tank Size Hull form Environment Natural Periods LR FLUIDS Typical Hull Protection System Max. W.L. Coating Min. W.L. Water ballast HPC + SA Coating High performance coating Cargo oil HPC High performance coating + cathodic protection system NB : Impressed current system not allowed in tanks 154

25 OGP Marine Risks Workshop Proceedings Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (25) Fabrication Tolerances and Welding tolerances should be in accordance with good shipbuilding practice, and agreed with LR special attention given to fatigue sensitive areas enhanced NDE levels will be necessary for identified fatigue sensitive areas assumptions used in analytical fatigue assessments to be consistent with construction NDE Testing of Welds - general Intersection of butts and seams & section welds Butt welds in plating Seam welds in plating Bilge keel butts Structural items fabricated with full/part penetration welding Penetrations & attachments to hull (sea inlets, piping, anode supports) (hopper knuckles, sheerstrake, hatchway coamings) Moonpool integration structure Topside support structure connections to hull structure Additional requirements for low temperature operations 155

26 International Association of Oil & Gas Producers Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (26) FPSO some In-service feedback FF1-3c 3c Some Design Life Issues Holistic approach for project / good communications Design for required service Compatibility of hull structural, systems and topsides interfaces Production equipment for required service Marine equipment robustness, particularly cargo/ballast and control/electrical systems OIWS requirements and corrosion protection Access arrangements Provision of spare parts 156

27 OGP Marine Risks Workshop Proceedings Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (27) Design- Frequent areas of concern Marine/offshore regulations and practices Topsides structure supports (alignment, motions) Hull vibration Crane specification and integration with hull Corrosion - general Access and escape routes compatibility Hazardous area and classification interfaces Piping systems (compatibility/flexibility) Topside equipment / motions / helicopter operations Marine / Topside system integration Use of GRP / FRP, pipework etc Wave impact and green sea loading Rudder and steering gear Laydown areas Effect of exhaust (heli-operations) Design Issues - Interfaces Interface Management is a critical influence on project success LR Project Manager provides interface between design and class/certification processes Technical interfaces to be developed include: Escape and access routing Hazardous area definition Venting arrangements (clear of hazardous areas and for inspection activities) Power generation and supply systems, normal and backup Bunding/prevention of spillage to main deck Control System and alarm circuits Crude oil pumping and piping system between vessel, process and offloading systems, including materials Fire Water, Cooling and Injection Water Heating system, Compressed air supply Topsides structure alignment at integration with deck Deck crane integration with hull structure Mooring system integration with hull structure 157

28 International Association of Oil & Gas Producers Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (28) Structural Inspection Carried out on location Provides detection / monitoring capacity Annual, intermediate & major surveys Major survey (5 years or continuous) IWS in lieu of dry docking Internal survey cleaning & gas freeing access arrangements/safety lighting/ventilation loading conditions FPSO Incident History Examples Hull Structure Shuttle tanker collision Bow Wave Impact Damage Tank Overpressurisation Seawater caisson preferential Corrosion Integration of surface and subsea corrosion protection Rudder/steering gear Marine Equipment Corrosion in cooling and heating systems due to poor fluid chemistry control Material problems on seawater systems Topsides Vibration induced failures Inadequate application of PFP Gas Turbine problems Produced Water Corrosion Damage due to wave impact (green water) Cargo Venting System failure Pipework and Production Train Leakage Riser / turret connections 158

29 OGP Marine Risks Workshop Proceedings Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (29) FPSO Incident History Statistics (Reported) Vessel System Nature of Incident No. of Incidents Hull Structure failure in heavy weather 1 Other structural failure 3 Collision 6 Topsides Structural failure in heavy weather 3 Process equipment failure 2 Fire 0 Machinery Engine Room fire 2 Engine Room power failure 1 Main engine failure 1 Rudder / steering gear failure 3 Other Hydrocarbon release 2 Explosions 0 Loss of anchor(s) 1 Ref : 22 vessels, approx 10 years of records See also Quantified Frequency of shuttle tanker collision during offtake operations,, IMCA Vibration Damage flare stack Vortex Beaufort 4-5 View A View A View B Turret Deckhouse View B Proposed reinforcements - two lateral braces. Brace on Port Side - cracked over 180 o at connection to forward chord. 159

30 International Association of Oil & Gas Producers Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (30) Mooring System Installation Problems Experienced Handling equipment failures Wire ropes Chains Poor tension control Loops formed Bird caging Lack of straightness Installed with twist Tangles & breakage Results from a Structural Survey Area shown Cargo/ballast tanks Example of Defect Locations on Side Shell Defect B B B B B B B 160

31 OGP Marine Risks Workshop Proceedings Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (31) Typical Damage Side shell longitudinal connection Shell plating Shell longitudinal Crack Face bar Web frame Web frame stiffener Crack Broken welding Examples of Internal Welded Repairs Side shell Side shell Fracture locations Bulkhead stiffener Stiffener Transverse bulkhead Side longitudinal Pillar stiffener Side shell New longitudinal section Stiffener with soft toe Backing bracket Bulkhead stiffener Transverse bulkhead Additional radius bracket Side longitudin al Additional lug 161

32 International Association of Oil & Gas Producers Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (32) Internal Repair - Non-Welded Hole drilled at crack termination Frame Longitudinal Crack Crack length Transverse web frame Bolted plates Stiffener Facing plate External girder reinforcement Local weld Grinding Section of hull End of LR Presentation 162

33 OGP Marine Risks Workshop Proceedings Tanker Conversions to FPSOs - Rob Potthurst, Lloyd s Register (33) LR Contact Details Bob Boon Business Development, Oil & Gas, London Tel : Fax : bob.boon@lr.org Rob Potthurst Offshore Floating Units, London Tel : Fax : robert.potthurst@lr.org 163

34 International Association of Oil & Gas Producers 164