Volve Subsea Removal. Trond Hofseth Subsea Operations Conference. Haugesund

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Kevin Roberts
5 years ago
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1 Volve Subsea Removal Trond Hofseth Subsea Operations Conference Haugesund

2 Recovery and disposal of: STL loading buoy Mid-Water Arch (MWA) 9 off mooring lines Approximately 1.600m of exposed risers and flowlines All subsea structures MWA gravity base structure (3 pieces) 3 off riser holdback anchors Drilling template SSIV 5 off GRP covers 10 off wellheads Volve Subsea Removal Overall scope of work Page footer text 2

3 Removal of STL Loading Buoy

4 Volve Subsea Removal - Cutting of riser and mooring line wire 4

5 Volve Subsea Removal Simops - Recovery of STL loading buoy

6 Volve Subsea Removal - Towing and lifting the STL loading buoy

Lessons learned Successful vessel simops operation. The method proved to be a well planned and well performed operation During tow of STL the winch readings was approx. 41 tonnes with a velocity of 7.

7 Lessons learned Successful vessel simops operation. The method proved to be a well planned and well performed operation During tow of STL the winch readings was approx. 41 tonnes with a velocity of 7.2 knots. This is a higher speed than expected on this load (ref. tow analysis) Cutting procedures and subsea tooling worked well, although the outer plastic layer on riser seems to clog the diamond wire Successful use of dyneema sling with additional protection for towing Towing calculations conservative with regards to towing forces Volve Subsea Removal Lessons learned - STL loading buoy

8 Removal of the Mid-Water Arch (MWA)

9 Volve Subsea Removal Mid Water Arch (MWA)

10 Volve Subsea Removal Recovery of MWA

11 Lessons learned The vessel crew was well prepared, proactive, selfgoing and extremely efficient Communication was excellent Cutting procedures and subsea tooling worked well Vessel A-frame with top roller proved to be perfect for the handling of MWA. This A-frame made it possible to get the whole MWA on deck instead of towing it to land Did allow vessel to use own procedures and routines which improved the operations Volve Subsea Removal Lessons Learned - Recovery of MWA

12 Cutting and recovery of 9 off mooring lines

13 Volve Subsea Removal Mooring line Page footer text 13

14 Volve Subsea Removal Cutting of mooring chain Page footer text 14

Observation Highly trained personell on vessel, correct equipment on vessel and good planning with input from vessel crew made this to a very smooth operation Lessons Learned Back filling and loose

15 Observation Highly trained personell on vessel, correct equipment on vessel and good planning with input from vessel crew made this to a very smooth operation Lessons Learned Back filling and loose sediments at the seabed created bad visibility when Skandi Vega ROV tried to connect rigging to the chain Testing and adjusting rotation speed on diamond blade for cutting of chains is highly recommended before mobilization Volve Subsea Removal Mooring line recovery

16 Cutting and recovery of flexible export lines

17 Volve Subsea Removal North Sea Giant Page footer text 17

Did cut approx. 1.600m of exposed pipe 8 inch oil export line and 7.

18 Did cut approx m of exposed pipe 8 inch oil export line and 7.4 inch gas export line Cut in 11m sections The cutter was upended on deck & deployed vertically Very efficient, landed onto flexible vertically, made the cut in 20 second The shear cutter was also used to lift the flexible pieces into the subsea baskets Volve Subsea Removal Cutting of flexibles using shear cutter

19 Volve Subsea Removal Relocation of cut flexibles pieces

20 Recovery of subsea structures

21 Volve Subsea Removal Recovery of subsea structures

22 Volve Subsea Removal Design vs actual lift-off weights

23 Cutting and recovery of wellheads

24 Volve Subsea Removal Drilling template recovered to NSG deck

25 Volve Subsea Removal Concrete removal at drilling template

26 Volve Subsea Removal Concrete removal at drilling template

27 Remove riser stumps (incl. tie-back connector) Drift clean wells internally and install internal cutting tool Cut through all casings and conductors below mudline Pull wellhead out of the cement / formation Recover wellhead to deck Cutting time approx. 5-6 hours Volve Subsea Removal Cutting of wellheads 27

28 Volve Subsea Removal Wellheads and upending frame

29 Volve Subsea Removal Wellheads cut and recovered to NSG deck

30 Summary of vessel operations

31 VESSEL CAMPAIGN SCOPE DURATION WHEN Wellservicer C0 Cut loose STL Buoy and MWA, SIMOPS. Cut all 9 chains at pile. Concrete removal at drilling template. Dredge and relocate GRP covers. General prep work Skandi Vega (CPI) C1 Tow STL Buoy and MWA to Vats. Recover all 9 mooring lines. Wires on winch and chains in locker 29 days May/June days May 2017 North Sea Giant C2 Cutting and recovery of exposed flexibles and risers 15 days Nov 2017 North Sea Giant C3 Release and recovery of 9 off tie-back connectors with 2m riser stumps on top. Cutting and recovery of 10 off wellheads. Campaign aborted due to perforated casings 14 days Oct 2017 North Sea Giant C4 Recovery of SSIV, 5 covers, 3 RHA, MWA GBS (3 lifts) North Sea Giant C3.1 Cutting and recovery of 10 off wellheads and 15 slot drilling template 10 Nov Dec 2017 Volve Subsea Removal Summary of vessel operations

32 AF Decom - Disposal Yard

33 Category Energy Recovery Disposal method In tons Landfill Recycled Reuse Technip Reuse AF Decom Sum Hazardous waste 1,58 1,28 2,86 Low radioactive waste/hazardous Waste 3,08 3,08 Metals 2231, , ,33 Non-Metals 24,12 351,06 375,18 Items sent for inspection to Statoil 31,48 31,48 Saleable 55,16 55,16 Sum 25,70 4, , ,50 31, ,09 Volve Subsea Removal Disposal summary 33

34 Summary

35 Decommissioning more complex than installation (lifting) Lack of As-Built information, especially from older fields Concrete removal takes a lot of time (double the time estimated) Good performance from all subcontractors Good performance from all three vessels 6% WOW October through December (North Sea Giant) Focus on planning as well as flexibility between campaigns and/or vessels required Great cooperation between Client and TechnipFMC teams No issues with NORM, but still important to measure Volve Subsea Removal Overall lessons learned 35

36 Recovery and disposal of: STL loading buoy Mid-Water Arch (MWA) 9 off mooring lines Approximately 1.600m of exposed risers and flowlines All subsea structures MWA gravity base structure (3 pieces) 3 off riser holdback anchors Drilling template SSIV 5 off GRP covers 10 off wellheads Volve Subsea Removal Overall scope of work Page footer text 36

37 Page footer text 37

Richard Rickett, General Manager Engineering and Procurement - March Case Study

Richard Rickett, General Manager Engineering and Procurement - March 2015 Case Study Case Study : Diverless Fast Track Repair of Mooring System Introduction ~ 300 floating production units in use around