The first production well on Statoil's Sygna field in the north-eastern part of the Statfjord area was spudded on 30 January.
Concern had been expressed beforehand over possible mooring problems for the subsea template owing to the soft seabed, reports Sygna project manager Kåre Søvik.
"We had to develop a special type of subsea template to cope with these bottom conditions," he says.
Bad weather and mooring problems meant that the well was spudded 19 days behind schedule. The aim is to bring the field into production on 1 August, a year after the North Sea development was approved by the Norwegian authorities.
The drilling rig Borgland Dolphin has been substantially modified before starting work on Sygna, and equipped with the RamRig drilling solution. According to Mr Søvik, the latter has suffered a number of running-in problems on other rigs.
Due to be completed this year, the drilling programme embraces a total of three wells.
The second will be a 7,200-metre injection well and one of the longest ever drilled from a mobile rig. It will start from an injection template on Statoil's Statfjord North satellite, 5.5 kilometres south of the Sygna template.
Overall oil recovery from Sygna is put at about 63 million barrels.