The Tordis subsea facility now lies safely on the seabed near the Gullfaks field in the North Sea. Lifting the 1,250-tonne structure on the Tordis field started on Sunday 12 August. During Monday 13 August the Saipem S7000 crane vessel completed the operation and left the Tordis field.
"Technically, the installation of the subsea separator went according to plan," says Rune Femsteinevik, Statoil's head of marine operations in the Tordis improved oil recovery (IOR) project.
"But obviously things are overshadowed by the tragic accident which occurred during the installation process."
A man from the Saipem company fell overboard while the installation was under way. His body was found later in the sea. The accident is under investigation.
"After such an incident, we would normally cease installation work and sail to land," notes Mr Femsteinevik.
"However, when the accident happened the Tordis structure lay at a depth of 180 metres and it was not possible to retrieve it to deck.
"For the safety of Saipem S7000 and the rest of the crew, we had no other option but to continue."
The marine operations on the Tordis field will continue over the next few months. The seabed separator will now be tied back to the Statoil-operated Gullfaks C platform with pipelines and control cables. In the course of this autumn subsea separation will commence on the Tordis field.
The Tordis separator allows the recovery of an extra 35 million barrels of oil from the field. Water and sand will be removed from the oil wells and pumped back into the Utsira formation at Gullfaks. This all takes place on the seabed, without an energy-intensive detour via a surface platform.
The Tordis field lies 11 kilometres north-west of Gullfaks C. Oil from the field is transported by pipeline to Gullfaks C for processing, storage and export.
Tordis came on stream in 1994.