Clair Ridge safely started up in November 2018, targeting 640 million barrels of recoverable resource and peak production of 120,000 barrels of oil a day.
The multi-billion-pound investment by BP and partners is designed to continue producing until 2050.
The Clair field was discovered in 1977, but challenging reservoir characteristics and the technological limits of the time meant it was 2001 before BP and partners approved a development plan for a first phase of development.
Phase One was brought on stream in 2005, targeting approximately 300 million barrels of recoverable reserves.
It was the first fixed offshore facility to be installed in the West of Shetland area.