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Subsea cable laying: from theory to practice

HAL

IFAX

, 6 N

OVE

MBE

R 2

014

Test site background 1. Location 2. Description

Our experience 1. Initial cable design 2. Contractor requested change 3. The compromise 4. Initial logistics 5. Unforeseen event 6. Agreed solution between all parties 7. Revised logistics 8. Cable burial

Conclusions

Test site background

LOCATION 1

BILBAO

DONOSTIA SAN SEBASTIÁN

VITORIA-GAZTEIZ

ARMINTZA

Biscay Marine Energy Platform

DESCRIPTION

Test centre ready to operate 2

• 4 Berths 20 MW connected to the grid • Environmental monitoring • Water depth 50-90 m • 24/7 Surveillance and emergency response • Close enough for fast access

Our experience

INITIAL CABLE DESIGN 1

Main Characteristics

•3 phases

•13.2 kV •5 MW

Counter helix double armour

2

Initial cable design required carousel

The contractor requested a change to simple armoured cable to avoid carousel

CONTRACTOR REQUESTED CHANGE

3

Double armoured cable without counter helix

•Storable in a hold

•No necessity for a carousel

THE COMPROMISE

4 INITIAL LOGISTICS

+

+ +

Sent vessel with connectors to Drammen Pick up subsea cables During journey to Bilbao technicians joined connectors and cables Laying of the four Subsea cables

Not viable – Alternative cable was not-sufficiently coilable

5 UNFORESEEN EVENT

6

Last minute all party meeting in Drammen Several solutions suggested

Barge with cables stored on a carousel

AGREE SOLUTION BETWEEN ALL PARTIES

7 REVISED LOGISTICS

+

+ +

Sent vessel with connectors directly to Bilbao

Barge with subsea cables from Drammen to Bilbao

Transfer cables and the connectors from barge to vessel one by one

Laying of the subsea cables one by one

+

+

8

•Non-consolidated substrate not as expected

•Inadequate equipment of the vessel

Cable burial carried out by divers

CABLE BURIAL

Conclusions

Lessons learnt

1

Expect the unexpected: technical & non-technical issues

Problem solving: all parties must work together as a team

Detailed seabed studies best carried out immediately prior to the cable laying

CONCLUSIONS

Thank you very much Dorleta Marina

dmarina@bimep.com