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FPSOs are a Mature & Versatile FPS Technology

Turret Mooring Design – Some Challenges and Solutions FPSO Forum 2004 NUS, Singapore Arun Duggal FMC SOFEC Floating Systems www.sofec.com 31 March 2004. FPSOs are a Mature & Versatile FPS Technology. Over 100 units in operation worldwide FPSO total > than all other FPS combined

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FPSOs are a Mature & Versatile FPS Technology

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  1. Turret Mooring Design – Some Challenges and SolutionsFPSO Forum 2004NUS, SingaporeArun DuggalFMC SOFEC Floating Systemswww.sofec.com31 March 2004

  2. FPSOs are a Mature & Versatile FPS Technology • Over 100 units in operation worldwide • FPSO total > than all other FPS combined • Water depth range 20 m to > 1,400 meters • 1 to 100+ risers • 10,000 bbl – 250,000 bbls/day • Up to 2,000,000+ bbls storage • Benign (West Africa) to Extreme Environments (North Atlantic) • Various flavors: • Turret-moored • Spread-moored • Yoke-moored • Hawser-moored

  3. Typical Permanent Internal Turret System Barracuda FPSO: Campos Basin 834m, 34 Risers Swivel Stack (Product/Lift/Controls) Manifolds + Pig Launching/Receiving Anchor Leg + Riser Pull-In Equipment Bearing (only upper in this case) Turret Shaft / Riser Guide Tubes Chain Table (Hawse Pipes/Chain Supports) 6 Anchor Legs + 34 Risers

  4. Turret Mooring of Production Vessels Design Considerations • Vessel Particulars • Storage / Tonnage • Topsides Layout • Vessel Motions • Environment • Water Depth • Waves • Wind • Current • Mooring System • Anchor Legs • Anchors • Risers • Thrusters & DP Control • Turret Design • Configuration • Size • Location • Loads • Fluid-Transfer Requirements • Well Heads • Subsea Manifolding • Risers • Turret Manifolding • Swivels • Offloading • Pigging

  5. Some Current Turret Mooring Challenges • More Complex Turret Systems • Large number of risers • Increased requirements for turret mounted equipment • High pressures • Riser Systems for very Shallow or Deep Water • Project Schedule • Short, fast-track schedules • Project Design Basis not well defined • Interfaces and Communication • Installation in Deepwater • Installation engineering, equipment, costs

  6. Example 1: Fast-Track FPSO for Shallow Water • Su Tu Den FPSO, Vietnam • MODEC, Inc + FMC SOFEC + ConocoPhillips • Newbuild FPSO (80,000 bbl oil/day) • Schedule: Contact to First Oil – 19 months • Turret Delivery Schedule – 12 months • Shallow Water (48m water depth) • Harsh Environment (100-yr wave of 8.1m Hs) • Large Number of Risers (12)

  7. Project Milestones • 2002 Mar. Contract Award (LOI)(2002/03/21) • 2002 Apr. Order Long Lead Items – bearing, forgings, process • 2002 Jun. Mooring Design Complete • 2002 Aug. Turret Fabrication Begins (MSE) • 2002 Oct. Hull Fabrication Begins (Samsung) • 2002 Nov. Preliminary Riser Design Complete • 2002 Dec. Topside Fabrication Begins • 2003 Mar. Drydock – Block Assembly Begins • 2003 Apr. Start Topside Module and Turret Installation • 2003 May Launching • 2003 Jul. Start Shipyard Commissioning • 2003 Sep. Tow Out • 2003 Oct. Offshore Installation • 2003 Oct. 1st Oil (2003/10/29)

  8. STD Turret Mooring Design & Fabrication • Use Standard Components & Design • SOFEC Large External Turret Design • Bearing Capacity exceeds anticipated Design Loads • Allows order of main components before final loads derived • Design Riser Configuration Flexibility in Chain Table Design/Fabrication • Clearly Define all Structural and Fluid transfer Interfaces at Turret Support Structure • Parallel Design and Fabrication Effort • Easy / Quick Integration with Vessel

  9. Riser & Mooring Design in Shallow Water

  10. Mooring and Riser Design 2

  11. Integration of Turret & Vessel

  12. First Oil: November 2003

  13. Example 2: Very Large Turret • Application • FPSO weathervaning SPM • Large field (>100,000 bbld) • 50 to 100+ risers • Deep to ultra deep water • Worldwide • Weathervaning advantages • Mooring tensions • Tandem offloading • Simplified turret structure • Allows for simple interface with vessel • Robust bearing system • Large Decks for Flowline Manifolding, and other Equipment • Efficient Mooring & Riser Installation Equipment

  14. VLT: Deep Water, Large Capacity Internal Turret Torque Arm Pull-In Deck Swivel Stack & Torque Tube Piping / Manifolding Radial Bearing Main Deck Vertical Bearing Riser Hang-Off I-Tubes Support Columns Chain Supports Chain Table Anchor Legs Risers & Bend Stiffeners

  15. VLT Chain Table • 3x3 mooring provides 3 riser corridors • Riser quantity defines chain table (and turret) diameter • 60 risers - 22 m dia • 90 risers - 31 m dia • 120 risers - 40 m dia • 2 riser rows maximum • No shadowing to allow inner row installation and replacement

  16. VLT Main Deck • Supports all loads, including: • Riser hang-off loads • Mooring loads through chain table and support columns • Turret self weight • Depth-to-diameter ratio is a key design parameter • Flexibility to move with vessel • Strength to support risers, mooring and turret weight loads • 2.5 m depth / 32 m diameter for a 90 riser VLT

  17. Conclusions • Turret Moored FPSOs are a Very Mature Technology • Design for Load Transfer is typically not an issue • Current challenges mostly associated with Fluid Transfer • Large Number of Risers • High Pressure • Manifolding • Subsea Intervention & Control • Project Parameters also Impact Turret Mooring Design • Schedule • Fast-track: 18 – 22 months • Complex systems require more commissioning time • Communication & Interfaces – among various contractors / client • Knowledge of others scope of work, issues, etc.

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