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2 Decommissioning of Flexible Flowlines Using Reeled Pipelay Vessels Michael O Donnell Engineer Subsea 7

3 Introduction Introduction to Reeled Rigid Pipelay Spooling pipelines Installing pipelines SAL Flowline Recovery Introduction Scope of work Engineering requirements SAL Flowline Offloading Scope of work Engineering requirements Conclusion Summary Lessons Learned

4 Introduction Seven Navica Equipment: Main Reel Adjustable Pipelay Ramp Tensioner, Aligner, Clamp and Roller-box

5 Introduction Seven Navica Pipeline Spooling: Rigid pipelines spooled onto vessel at one of Subsea 7 s spoolbases

6 Introduction Seven Navica Pipeline Installation: Rigid pipelines installed in water depth of 18 1,860m

7 SAL Flowline Recovery Introduction Single Anchor Loading System (SAL) Remote offloading of product from Kittiwake to transport vessels 2 x 1.5km flowlines connected via mid-line connection GKA export pipeline has made SAL redundant SAL flowline to be recovered and re-used in the future Kittiwake Field, Central North Sea Block 21/18 Water depth 85m

8 SAL Flowline Recovery Scope of Work Recover SAL flowline to the Seven Navica Ensure flowline and end terminations are protected Modify Seven Navica to accommodate product Product Details Outside diameter 270mm Internal diameter 203mm Overall length 3,045m Weight in air empty 95kg/m MBR storage 1.75m MBR operational 2.6m Flowline trenched (uncertainty of quality and quantity)

9 SAL Flowline Recovery Engineering Requirements Unable to utilise pipe clamp due to chute installation on pipelay ramp

10 SAL Flowline Recovery Engineering Requirements Sailor s Cap and Suitcase wire pre-installed to support leading head of flowline Performed load transfer from A&R wire to suitcase wire during recovery Main reel acted as a winch to spool flowline onto reel

11 SAL Flowline Recovery Engineering Requirements Flowline integrity to be maintained throughout operations

12 SAL Flowline Recovery Engineering Requirements Addition of Subsea 7 designed half shells at mid-line connection proved successful

13 SAL Flowline Recovery Engineering Requirements Addition of rubberised packing solution protected the product underneath the mid-line connection

14 SAL Flowline Recovery Recovery Completed 2 x Flexible Flowlines recovered onto Seven Navica main reel Leading head protected by Sailor s Cap Mid-line connection protected using half shells and rubber packing solution Tail end secured within pipelay ramp

15 SAL Flowline Offloading Scope of Work Set up the quayside for the offloading operations Offload the SAL flowline onto two separate storage reels Disconnect the mid-line connection onboard the vessel to split the flowlines Ensure flowline integrity was maintained throughout

16 SAL Flowline Offloading Vessel Setup Seven Navica moored at an angle to aid flowline offloading Chute, level winder, tensioner, quayside crane, and reel required for offloading

17 SAL Flowline Offloading First Flowline Complete Mid-line connection disconnected and tail end fed back to storage reel Shoreside crane allowed controlled spooling of tail end of flowline

18 SAL Flowline Offloading Storage Reel Mobilisation/Demobilisation Empty storage reel positioned beyond full reel Full reel lifted and repositioned along the quay Empty reel positioned and prepared for spooling operations Adverse weather conditions delayed operations

19 SAL Flowline Offloading Second Flowline Spooling Principles from previous spooling operations applied Spooling performed more efficiently with experience gained from first flowline Partitioned reel allowed faster spooling

20 Conclusion Summary Subsea 7 have demonstrated the successful recovery of a flexible product for re-use using a rigid pipelay vessel Lessons Learned Knowledge of flowline properties desirable at engineering phase Partitioned reel allowed for efficient spooling operations whilst protecting the end termination Offloading port selection critical to flowline offloading Transferable knowledge applicable to our larger pipelay vessel Seven Oceans Seven Navica Seven Oceans

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