Both governments had to approve the principles for shutting down and removing the installations, and this process took several years. Under the Frigg treaty between Norway and the UK, the field was to be treated as far as possible as a unit. The sides agreed that the disposal of all the facilities on Frigg should be covered in a single cessation plan, which took account of legislation in both countries. This accorded with the principles which had always underlain the operation of Frigg.
Detailed guidelines relating to the environmental impact were drawn up, guided by international conventions such as Ospar.[REMOVE]Fotnote: Oslo-Paris convention for the protection of the marine environment of the north-east Atlantic The latter specifies that all installations must basically be removed, with some exceptions for heavier structures.[REMOVE]Fotnote: Ospar decision 98/3 on the disposal of disused offshore installations specifies that steel installations weighing more than 10 000 tonnes and concrete GBSs can be left behind, providing they are identified with beacons to prevent any hazard to shipping. A number of re-use proposals were made, particularly of the concrete gravity base structures. These included serving as fish reefs or as foundations for wind turbines or carbon-free gas-fired power stations. But many of these options were extremely uncertain in technical terms, and none were regarded as financially interesting.
Different options for taking away the installations were also studied, including complete removal from the field. The GBSs proved difficult to move. An accident while they were being refloated could have major consequences, particularly in terms of cost and risks to people. It was finally decided to remove more or less everything except the GBSs and drill cuttings on the seabed. Pipelines and cables on the seabed would be taken away. MCP-01 was also included in the removal project. The process on Frigg is due be completed by 2012, with only the GBSs for TP1, TCP2 and CDP1 left behind. The GBS for MCP-01 will also remain after the topside has been removed, which is due by 2010.
For further details, see: Removing oil and gas installationsFrøy shut inNew official name for Total