Borgland Dolphin arrived on Statoil's Sygna field in the Statfjord area of the North Sea on 16 January, almost 18 months later than originally planned.
The group chartered this drilling rig from Fred Olsen Energy in the summer of 1997 for a period of six years from the third quarter of 1998.
It was immediately docked at a shipyard in Belfast for extensive modifications, but the group only agreed in late 1999-early 2000 to accept the unit.
This delay has primarily affected the Statfjord operations team, reports Terje Vatn, manager for the rig sector in the drilling and well operations unit.
It has had to secure a replacement rig to keep its drilling programme on schedule, and the original workload which Borgland Dolphin was chartered to implement has been correspondingly reduced.
The rig was due to drill in the Statfjord area for the first three years of its charter, followed by three years of exploration drilling. However, the Statfjord involvement has been reduced to two years.
Statoil faces a challenge in keeping Borgland Dolphin fully employed during the final four years of the charter, says Mr Vatn.