how to safely plan and conduct riser replacement … 2013/temadag om...– simops (onboard vessel)...

How to safely plan and conduct riser replacement operations

November 26th, 2013

Xavier Heraudeau

2 7-Nov-13

Introduction

Recovery risks management

Subsea 7 vessel capabilities

Key points to plan for recovery

Lessons learned extract

Agenda

3 Page 27-Nov-13

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 Lazy wave (Reversed) Pliant wave Lazy S

4 Page 27-Nov-13

Introduction


– 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

5 Page 27-Nov-13

Introduction


– 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

6 Page 27-Nov-13

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 Project

Norsk Hydro 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

7 Page 27-Nov-13

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

– ...

8 Page 27-Nov-13

Introduction





Agenda

9 Page 27-Nov-13


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

10 Page 27-Nov-13



BSLM release mechanism mal-functioning

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

11 Page 27-Nov-13

Operational risks management


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

12 Page 27-Nov-13

Introduction





Agenda

13 Page 27-Nov-13


• Skandi Acergy

400 Te AHC Knuckle Boom Crane


FLS (125Te Flexible Lay System). + 7.2x7.2 m Moonpool

Flexible Load-out Spread

3000Te Below Deck Carousel

2 off ROV (DP work class). Deployed through moonpools

3 off 10Te deck winches

1 off 32Te Initiation winch

Principal Particulars

Length overall 157 m

Breadth 27 m

Depth to main deck 12 m

Draught 7.00 m

Deck area usable 2100 m2

Transit speed 15 kts

Maximum speed 18 kts

Accommodation 140

DP Class III

Capacities

Flexible/Umbilical installation

Riser installation

Spool/Jumper Installation

Structures/Manifold Installation

Protection structures

14 Page 27-Nov-13


• Skandi 7


Length overall 120.7 m

Breadth 23 m


Draught 7 m



Maximum speed 16 kts

Accommodation 114 persons

DP Class III

Capacities

• Flexible/Umbilical installation

• Riser installation

• Spool/Jumper Installation

• Structure/Manifold Installation

• Inspection and maintenance work

• Support vessel operation


VLS (260Te Vertical Lay System) + 7.2 x 7.2 m Moonpool

2 off ROV (DP work class)

15 Page 27-Nov-13


• Normand Oceanic



Breadth 27 m


Draught 7.00 m



Maximum speed 17,6 kts

Accommodation 140

DP Class III

Capacities


Riser installation



Protection structures



2 off ROV (DP work class). Deployed by A-frames

4 off 12Te deck winches

16 Page 27-Nov-13


• 7 Pacific



Breadth 24 m


Draught 7.00 m


Transit speed 12,5 kts

Maximum speed 13,5 kts

Accommodation 100

DP Class II

Capacities


Riser installation





2 off ROV (DP work class).

VLS (260Te Vertical Lay System). + 7.2 x 7.2 m Moonpool

17 Page 27-Nov-13


• Skandi Acergy - Storage

– 24m OD / 6m high under-deck carousel

– RDS possible on deck:

• Flowlines: up to 6-slots

• Risers: up to 5 slots

18 Page 27-Nov-13


• Skandi Acergy - Lifting equipment

• Present flexlay vessels, 1 slide per vessel,

19 Page 27-Nov-13


• 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

20 Page 27-Nov-13

Introduction





Agenda

21 Page 27-Nov-13

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

22 Page 27-Nov-13

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.

23 Page 27-Nov-13

Introduction





Agenda

24 Page 27-Nov-13

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

25 Page 27-Nov-13

how to safely plan and conduct riser replacement … 2013/temadag om...– simops (onboard vessel)...

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