Valhall became the first field on the Norwegian continental shelf (NCS) to base its power supplies exclusively on hydroelectricity transmitted by submarine cable from land. Completed in 2013, this groundbreaking project has attracted much attention. Pertinent questions include which decisions underpinned BP’s technology shift, how the new development on Valhall proceeded and which other fields have opted for power from shore. Another issue is what environmentalists think of such a solution.

The Valhall redevelopment (VRD) project was launched in the early 2000s after it became clear that the field would stay on stream for much longer than initially anticipated.

The seabed on Ekofisk – the neighbouring field to Valhall – was found to be subsiding in the mid-1980s. After this was confirmed by surveyor Bloms Oppmåling, Amoco hired the same company to check Valhall, which has a similar carbonate reservoir to Ekofisk’s.

A new combined production and hotel (PH) platform was installed for various reasons – as described in a separate article – on Valhall in 2012.

The blend of water, oil and gas flowing in liquid form from the Valhall wells must be treated with a range of processes before being exported from the field. The various components in this wellstream must be separated from each other and processed differently in order to meet the specifications set for them. Equipment on the original process and compression platform (Valhall PCP) was designed to handle outputs which could range on a daily basis between 168 000-60 000 barrels (26 700-9 500 cubic metres) of oil and six to 9.9 million cu.m of gas.