Involving some 350 tonnes of equipment on the seabed, the world's first permanently-installed seismic array for monitoring a complete producing oilfield is being installed over the next seven weeks by Subsea 7 out at the Valhall location.

The oil company is investing more than $50 million in a "life of field seismic" system that should yield extra oil and enable more efficient management of the reservoir at this 21-year-old field in the southern part of the Norwegian sector.

BP