Oil production began from Statoil's Åsgard development in the Norwegian Sea at 03.33 on Wednesday 19 May.
Crude is currently flowing to the Åsgard A production ship from a single well, but seven additional producers and six gas injection wells will be brought on stream during the next few weeks.
Plans call for output to run at around 155,000 barrels per day over the next few months.
The processing plant on Åsgard A is likely to need a running-in period before production can be fully stabilised.
Facilities on the field currently comprise the ship, subsea templates and flowlines/risers linking the seabed wells with the vessel. A total of 17 templates have been installed so far.
Plateau production from Åsgard A, which ranks as one of the world's largest production ships, is due to lie around 200,000 barrels of oil per day.
Measuring 278 metres long, this vessel can store 910,000 barrels. Its design life is 20 years, while the field is expected to remain on stream for half a century.