Anchor operations for Jack-up barge in offshore wind farms during service – Customers’ perspectiveThere are several ways of moving jack up barges into a location close to a offshore wind turbine. There are also several issues that need to be addressed.This presentation is about the anchors and marine rig move procedures.

Feb. 2012, JOFLO, TMS Vestas Offshore

2 | Vestas Offshore / O&M

Vestas Offshore - track record

Differences in jack up barge class

Work environment Operation Often seen problemsOlie & gas 4-6 anchors, 2-3 tugs Collision with installationWind and renewables 2-4 anchors, 1-2 tugs Damage to cablesInshore and harbors 2-3 tugs Damage to rigDredging, cpt. and diving Misc. Damage to infrastructure

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WTG service work

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Create a safe working environment in the nacelle

Notes to guidelines and rules

There are good and detailed rules for Oil and gasRenewables have guidelines based on Oil and Gas

BWEA guidelines to get a common safe operation for small jack ups near shore.Standards come from Oil and Gas, used together with experience from small jack up operations.

BWEA too restrictive and has a wrong risk profile (inherited from Oil & Gas).

Renewables should have another guideline than Oil & Gas based on a different risk profile.

• The vessels are different from Oil & Gas• The amount of operations are much higher• MET-Ocean condition is different and much more complex• Seabed condition and infrastructure are different

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Optimal operation for avoiding damage to cable & pipes

Standard in Vestas Offshore for moving a 4 point mooring jack up barge in the Wind farms. Using 2 anchors and 2 tugs.

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Current direction

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Optimal operation to avoid collision between Rig and Structure

Standard in Oil & Gas Offshore for moving a 4 point mooring jack up barge. Using 4 anchors and 3 tugs.

Compare risk in the 2 scenarios

Risk type (1-5)5 high risk3 Normal operation1 low risk

2 anchors and 2 tugs, not crossing cables with anchor or wires rig >15m. distance

4 anchors and 2-3 tugs, crossing cables with anchors and wires. Flotation on wires

Barge collision with structure 3 2

Damage to cables from wires 2 4

Damage to cables from anchor 1 4

Tug collision with structure 3 2

Delays / weather risk 3 4

Damage to structure from wires 2 3

Damage to people on rig 2 3

Damage to people on tug 2 4

Reaction time for unforeseen events 2 3

Anchor & wire position errors 2 3

Anchor, winch & wire failures 2 3

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Summary

• Each operation needs to be evaluated based on the entire operation taking weather, logistic, infrastructure and available vessels into consideration

• Focus should be on the overall risk, evaluating all aspects of the operation• Cost of energy must come down• Lack of suitable Jack-up’s in the marked• JUB owners back office functions should be prepared and staffed for high

requirements for documentation• More cooperation between Customers and consultants needed.• Consultants are not aligned• Guidelines should not be considered as rules• HSE always come first!

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