Cns Subsea Completes North Sea Project for Shell

Subsea cable lay and burial specialists Cns Subsea Ltd has just successfully completed a £2 million contract for Shell. The Aberdeen-based firm tendered for the repair of the Brent Charlie/Dunlin Alpha power cable located in the Northern North Sea.

Their experience of power cables, coupled with their knowledge of the sensitive operations to be carried out in minimal time, was a key factor in the contract award.

Cns undertook the requisite project engineering and methodology to tackle the repair of the power cable in a very short period of 3 weeks. The company then mobilised the MV Botnica from Norway to its base in Teesside where the vessel was equipped with Cns' state-of-the-art remotely operated jetting system - the Olympian T2.

The Olympian T2 was modified to accommodate a specialist cable cutter and recovery tool and then installed on the vessel along with Cns' cable handling, repair and storage equipment.

Cns conducted trials at Buchan Deep offshore Peterhead prior to heading out to the Northern North Sea.

The first part of the job was to locate the buried cable in water depths of 160 meters and remove the protective rock covering the cable. Using specialist tracking equipment Cns then identified the precise location of the fault. A new 500 meter section of cable was spliced in place and then the cable was re-laid over the pipeline crossing and safely reburied ensuring long-term integrity of the replacement cable.

John Sinclair, managing director of Cns, says: "Our ability to, in a short space of time, identify the challenges, plan for the unforeseen and mobilise the necessary technical know-how, gained in the offshore renewable energy sector, enabled us to effect the repair in the shortest possible timescale. The Olympian T2 can be launched and recovered in harsher environmental conditions than other burial vehicles which increases the operational window caused by unpredictable weather. Equally, identifying and working round the issues ensures that the project was carried out with full attention to the integrity of the cable and safety or the personnel as well as the project being delivered quickly and to budget."