How to safely plan and conduct riser replacement operations November 26th, 2013 Xavier Heraudeau Introduction Recovery risks management Agenda Subsea 7 vessel capabilities Key points to plan for recovery Lessons learned extract 27-Nov-13 Page 2 Introduction • What is a riser replacement operation ? – Reasons: • • • • Field life extension Riser life termination Damage to product (accidental or fatigue) New requirements (flow for flexibles, controls / power for umbilicals / cables) – Configurations mostly met for replacement scopes in North Sea: • Static risers in J-tubes • Dynamic risers Steep wave 27-Nov-13 Page 3 Lazy wave (Reversed) Pliant wave Lazy S Introduction • What is a riser replacement operation ? – Overview of recovery operations: key steps • Topside end disconnection from floater • Transfer of topside end from floater to vessel • Handling of topside end through layspread • Wave un-shaping • Hold-down tether disconnection and counter-weight management • Accessories removal • Subsea connector break-off • Subsea end storage 27-Nov-13 Page 4 Introduction • What is a riser replacement operation ? – Overview of installation operations key steps: • Topside end handling onboard vessel • Transfer of topside end to floater • Accessories assembly • Counter weight management • Wave shaping • Tethers connections • Subsea connector installation 27-Nov-13 Page 5 Introduction • Subsea 7 Portfolio involving flexible risers replacement only Project Client Year Riser Type and Quantity Skuld Marine Installation Statoil 2012 1 x 11.5" Production Riser Marulk Subsea Installation Statoil 2011 1 x 10.5" Production Riser Njord A Riser Replacement StatoilHydro 2010 1 x 6" Production Riser Snorre B Riser Replacement StatoilHydro 2009-2010 2 x 5" Production Risers and 1 x 8" Production Riser Visund Future Riser StatoilHydro 2009 3 x 6" Production Risers Njord Gas Export Line & Riser Option Norsk Hydro Project 2007 2 x 6" Production Risers and 1 x 10" Gas Export Riser Veslefrikk Riser Replacements Statoil 2003 1 x 8" Water Injection Riser, 1 x 4" Mud Visund FPU Riser Replacement Statoil 2003 4 x 6" Production Risers Vigdis WI Riser Replacement Statoil 2002 1 x 10" Water Injection Riser Åsgard B Riser Replacement Statoil 2002 1 x 9" Gas Injection Riser Njord FPU Riser Replacement Norsk Hydro 2002 4 x 6" Gas Injection Risers, 1 x 6" Production Riser 27-Nov-13 Page 6 Introduction • Subsea 7 on-going projects involving Flex decomissionning in Norway – Statoil Subsea Lines Modification project • Subsea 7 Portfolio involving Flex decomissioning worldwide – Apache Van Gogh flowlines – Australia – Apache Ningaloo Vision flowlines – Australia (on-going) – Total Moho Bilondo riser – Congo – Suncor Terra Nova risers – Canada – Nexen Scott & Telford flowline – Scotland – ... 27-Nov-13 Page 7 Introduction Recovery risks management Agenda Subsea 7 vessel capabilities Key points to plan for recovery Lessons learned extract 27-Nov-13 Page 8 Recovery risks management Risk Consequence Some Mitigations Limited knowledge of annulus with only visual inspection of outer sheath 1.Pollution from annulus 2.Burst due to localised pressure 1.Annulus sampling tests 1.PPE ready on vessel 2.Annulus venting Flexible OD variations Bend stiffener not sliding Loose accessories Contingency procedures Flexible bore contents Pollution onboard vessel (connection break-off) Dedicated storage system PPE Contingency procedures Pre/de-commissioning activities tracability 27-Nov-13 Page 9 Recovery risks management Risk Consequence Some Mitigations BSLM release mechanism malfunctioning Delay in operation on SIMOPS Design that prevents locked BSLM Reversible procedures Vessel dependance to floater equipment Failure of winch may lead to stand-by in close proximity Plan for back-up procedures & equipment onboard floaters Closed I-tubes at bottom ends with potential debris 1.Dropped objects 2.Damage to product when lowering 1.Survey of I-tube 2.Design at hang-off to avoid dropped objects 27-Nov-13 Page 10 Operational risks management Risk Consequence Some Mitigations Extended operations in close proximity & SIMOPS in restricted weather 1.Restricted activities onboard production units 2.Increased required operational window 1.Qty of subsea operations limitation 2.Reversible procedures Extensive marine growth 1.Extended deck operations 2.Slippery working conditions 1.Pre-survey 2.Working area designed for marine growth material 2.Cleaning tools spares Dropped objects Damage to existing subsea infrastructures Risk assessments Shut-down 27-Nov-13 Page 11 Introduction Recovery risks management Agenda Subsea 7 vessel capabilities Key points to plan for recovery Lessons learned extract 27-Nov-13 Page 12 Subsea 7 vessel capabilities • Skandi Acergy Principal Particulars 400 Te AHC Knuckle Boom Crane Flexible Load-out Spread 100 Te AHC Knuckle Boom Crane 1 off 32Te Initiation winch Length overall Breadth Depth to main deck Draught Deck area usable Transit speed Maximum speed Accommodation DP Class 157 m 27 m 12 m 7.00 m 2100 m2 15 kts 18 kts 140 III Capacities 3 off 10Te deck winches FLS (125Te Flexible Lay System). + 7.2x7.2 m Moonpool 3000Te Below Deck Carousel 27-Nov-13 Page 13 2 off ROV (DP work class). Deployed through moonpools Flexible/Umbilical installation Riser installation Spool/Jumper Installation Structures/Manifold Installation Protection structures Subsea 7 vessel capabilities • Skandi 7 Principal Particulars Length overall Breadth Depth to main deck Draught Deck area usable Transit speed Maximum speed Accommodation DP Class 120.7 m 23 m 9m 7m 1125 m2 12 kts 16 kts 114 persons III Capacities • • • • • • Flexible/Umbilical installation Riser installation Spool/Jumper Installation Structure/Manifold Installation Inspection and maintenance work Support vessel operation 27-Nov-13 Page 14 250 Te AHC Knuckle Boom Crane VLS (260Te Vertical Lay System) + 7.2 x 7.2 m Moonpool 2 off ROV (DP work class) Subsea 7 vessel capabilities 400 Te AHC Knuckle Boom Crane • Normand Oceanic 100 Te AHC Knuckle Boom Crane 4 off 12Te deck winches Principal Particulars Capacities Length overall Breadth Depth to main deck Draught Deck area usable Transit speed Maximum speed Accommodation DP Class Flexible/Umbilical installation Riser installation Spool/Jumper Installation Structures/Manifold Installation Protection structures 27-Nov-13 Page 15 157 m 27 m 12 m 7.00 m 2100 m2 12 kts 17,6 kts 140 III 2 off ROV (DP work class). Deployed by A-frames Subsea 7 vessel capabilities • 7 Pacific 250 Te AHC Knuckle Boom Crane VLS (260Te Vertical Lay System). + 7.2 x 7.2 m Moonpool Principal Particulars Length overall Breadth Depth to main deck Draught Deck area usable Transit speed Maximum speed Accommodation DP Class 134 m 24 m 12 m 7.00 m 978 m2 12,5 kts 13,5 kts 100 II Capacities 30 Te AHC Knuckle Boom Crane 27-Nov-13 Page 16 2 off ROV (DP work class). Flexible/Umbilical installation Riser installation Spool/Jumper Installation Structures/Manifold Installation Subsea 7 vessel capabilities • Skandi Acergy - Storage – 24m OD / 6m high under-deck carousel – RDS possible on deck: • Flowlines: up to 6-slots • Risers: up to 5 slots 27-Nov-13 Page 17 Subsea 7 vessel capabilities • Skandi Acergy - Lifting equipment • Present flexlay vessels, 1 slide per vessel, 27-Nov-13 Page 18 Subsea 7 vessel capabilities • Skandi Acergy – Containment – – – – – All below can be generic to any vessel IBC tanks with pumping system Closed volume around hang-off area PPE for marine growth: same as working under rain. PPE for pipe contents: • • • • Integral rubber suit for pipe contents Rubber gloves & boots Face shield + protection glasses Mask • Skandi Acergy – Subsea equipment – LARS - Safe til Hs=6m – Up to 270kg lifting capacity 27-Nov-13 Page 19 Introduction Recovery risks management Agenda Subsea 7 vessel capabilities Key points to plan for recovery Lessons learned extract 27-Nov-13 Page 20 Recovery operations – key points to plan for • Platform operations – Contingency procedures in case of difficult disconnection or equipment failure – Function testing performed • Vessel operations – – – – Thorough planning of containment operations Thorough planning of operations at working area while heavy cleaning SIMOPS (onboard vessel) due to installation of aids Reversible installation or recovery operations to be aimed while SIMOPS in closed proximity – Schedule re-visited after preliminary visual survey (marine growth) • Subsea operations – Counter weight connection – Use of permanent clamp if possible – ROV installation of aids on product to be limited as much as possible – Trials to be planned for subsea installable aids 27-Nov-13 Page 21 Recovery operations – key points to plan for • Design requirements – All utilization of temporary installation aids to be designed in view of recovery operations – Assessment of aids design with permanent features (anodes) – Permanent accessories design: interfaced with Installation Contractor for aids connection and riser installability – Riser configuration (buoyancy section mainly) to be optimised for restricting use of counter weights – Topside BSLM selection for use at end of life – Monitoring of annulus and pressure release systems – Re-use of permanent equipment to be thouroughly assessed according to as-found conditions of equipment. 27-Nov-13 Page 22 Introduction Recovery risks management Agenda Subsea 7 vessel capabilities Key points to plan for recovery Lessons learned extract 27-Nov-13 Page 23 Extract of list of Lessons extra learned on how to address safely this operation – worldwide Lesson # Description LL-09599 Top tension variation evaluation at vessel during pull out with flexible pipe rupture at production unit LL-10533 Use of buoyancy module ballast cages LL-10201 & LL-03755 Marine Growth Removal Collar for Flexible Recovery LL-10202 Flexible Recovery - Product Packing LL-00987 Positioning of vessel during MWA Buoy preparation and recovery works LL-01983 Precom - management of pigs during product recovery LL-03699 Wire Deflector for riser pull-in LL-03781 Use of variable weight DMA LL-03788 Positioning of RDS & reel cradles for recovery operations LL-06647 Bend Stiffener Stopper Clamp and Tip Support 27-Nov-13 Page 24 27-Nov-13 Page 25