Staff operating the Foinaven floating production, storage and offloading vessel (FPSO) have voted to take strike action.
Unite union members voted by 96% for a strike on an 84% turnout. Continuous industrial action is now scheduled to take place from 5 August.
The Foinaven oil field - approximately 120 miles west of the Shetland Isles within the Faroes/Shetland Trough - is currently run by Altera under contract to BP, but when that ends next month it is due to be towed to Hunterston in Ayrshire.