Construction workers were called to muster after a safety incident on BP’s Clair Ridge platform.
The oil major’s project is currently being constructed West of Shetland.
It is believed there was a small fire which triggered alarms at around 4.20pm yesterday.
A spokeswoman for BP said:”We are investigating a small safety incident which occurred on Clair Ridge yesterday afternoon (Wednesday 19th October). Clair Ridge is currently being constructed and is therefore completely hydrocarbon free.
“As part of the construction, there is a significant amount of welding taking place and we believe that an element of this activity triggered the general alarm. It was a controlled incident with everyone back at work 45 minutes later.”
It comes after BP was forced to shut down production at its separate Clair platform after a suspected oil leak earlier this month.
Almost 30 surveillance flights have been carried out to assess the impact of the oil’s dispersal in the surrounding waters.Production is still shut down.
Earlier this year, BP announced it had completed the installation of the two platforms, and revealed plans to create more than 500 new North Sea jobs.
The project involves the second phase of development of the Clair field, which lies 46 miles west of Shetland and has an estimated eight billion barrels of oil in place.
First oil is expected at the end of 2017.