Excursions Challenges! 13 th March 2013 Arnfinn Anfindsen Diving Manager-Norway

1. Excursions Challenges! 13th March 2013 Arnfinn Anfindsen Diving Manager-Norway

2. Background/History Excursions as per Norsok U100 Various scenarios • A – Working in a trench • B – Welding Habitat/H-Frames • C – Subsea Manifold • D – X-TreeProtection cover An Offshore Managers Frustration UK UnlimitedExcursionTable References Agenda

3. History/Background Facts: Vessel : DSV Seven Pelican Operation: B11 Bypass Project preparatory work (German Sector) When: May 2012 Seabed dept: 32ms before excavation Operational issue:  Limited excursions for given depth Safety issue: Diving bell, stage and clump weights located minimum 2 meters above seabed Deviations:Norsok U-100 section 8.2.3.4, and  to Subsea 7 Saturation Diving Manual Chapter 10

4. Norsok U100 8.2.3.4 Excursions • Procedures for excursions shall be prepared. If excursions are extended compared to Table 8, longer stays at living depth prior to start of decompression should be considered. Decompression shall not start with an upward excursion. There shall be a minimum 8 h hold at living depth prior to decompression after an excursion.

5. As a minimum, the procedures shall define; • a) living depth, • b) working depth, • c) limitations of excursion after change of living and/or working depth, • d) maximum rates for compression and decompression during excursion, • e) maximum pressure increase and decrease during the excursion. It is of special importance to restrict the use and distance of upward excursions. The maximum ascent rate during excursion is 10 msw/min.

6. Selection of Excursion Types and Distances – Norway • Usually, it will be possible to select one of several different storage depth/excursion scenarios for carrying out a specific job. As a general rule, choose the storage depth which minimises ascending excursion distances during the dive operation. Thus, prefer: • Descending excursions rather than ascending excursions. • Storage depth as close to the working depths as practical. In order that operational excursion distances are not affected by the distance between the two, they should be as close as practical. • Planning of the dive is essential!

7. Diving Excursions – Table 8

8. Diving Excursion - Working in a trench

9. Bell door -27 msw Min 3 m Bottom of clumpweight -30 msw Norsok U100 5m excursionbased on LD 27m 5m Excursion needed 9 m Min 2 m 4 m

10. Diving Excursion – Umbilical Length Umb. length: ~28m Bottomofbell: ~28m

11. How to obtain consensus for proposedsolutuion • Involvementofthefollowingpersonnel is essential; • DivingResponsibleDoctor -Contractor • Health Department– Contractor • Offshore Manager • Safety Delegate Divers • Contractors HSE Department • ContractorDiving Manager • Company ResponsibleDivingDoctor • Company Diving Advisor • Company HSE Dep

12. Excursion - solution • Divers maximum in water time 4 hours (vs normal 5,5 hours) to avoid Jo-Jo effect during break for rest break, and to reduce total time at maximum excursion depth • Increase hold period from 8 hours to 12 hours prior to final decompression The diving procedure for extended downward excursion  will include following: • Storage dept 27 MSW • Working depth, from 32 to 36 MSW • There is no changes in divers living or working depths • The maximum ascent rate during excursion is 10 msw/min. • Maximum pressure increase and decrease during the excursion is within following window: 3.7 to 4.6 ATA. • There is no plan to use upward excursions and should this be necessary there will be no changes to limitations as described in NORSOK U-100.

14. Client B – Welding Habitats/Lifting Frames

15. Client C – Subsea Manifold Bell door -109 msw Min 3 m Bottom of clumpweight -112 msw Min 3 m Top of manifold 115m Excursion needed 12 m 6m

16. Client D – X-TreeProtectionStructure Min 3 m Excursion needed 15 m 11m

17. An Offshore Managers frustration “I am fully aware of all this and more, which is my whole point. The best way to deal with a hazard is to remove the hazard. We could effectively do this by raising the bell, i.e. changing the excursions. With the current restrictions we only have 1.7 metre vertical separation, it is not often in the North sea that the sea state is less than that.  Everyone keeps quoting “set up for drift off“ etc. etc. No one has mentioned drive off, which can be in any direction. The simple solution is to allow some tolerance in the excursions. There is as you are aware a precedent for this as both Norsok U100 and our Subsea 7 diving Excursion tables has tested that. Why can’t we get a similar decision to enhance safety? I am having safety, safety, safety pointed out to me time and time again, yet time and time again  beach support is “safetying” us into less safe situations. “No one seems to want to listen to the people who are doing the work.” «NN» Offshore Manager Subsea 7 DSV

18. UK «Unlimited» ExcursionTables • Subsea 7 has wide operational experience in shallow saturation diving on the Southern part of the UK, Dutch and German sectors in the North Sea using Subsea 7 Sat Diving Manual UK Excursions (US-Navy). • Subsea 7 has not experienced any decompression sickness or other injuries from the high number of dives performed from dives performedon this table.

19. References • Norsok U100 section 8.2.3.4 Excursions • Subsea 7 Group Diving Manual  Vol 2 – Diving Techniques clause 2.8.2 Excursion Limits • OD 91-88 (Eng) Comparison of Saturation diving tables and preparation of Framework for standardisation of tables • OD 91-12 (NO) Rapport om sammenligning av metningsdyddetabeller og utarbeidelse av rammebetingelser for standardisering