Mystery remains over the origin of an oil sheen that led to a North Sea production shutdown.
Respol Sinopec was forced to halt the flow at the Montrose Alpha and Arbroath platforms after a supply vessel raised the alarm at 10am on March 11
Crew on the vessel alerted the installation managers after spotting the sheen on the surface of the sea near the Monstrose area platforms.
Repsol said production was shutdown on a subsea pipeline then restarted at a lower pressure than normal to check if there was a leak.
However no release was detected and production has now resumed at normal rates.
Tests later ruled out the possibility that the hydrocarbon release came from either platform as the samples from the sheen did not match those from the pipeline.
Subsea 7’s DSV the Seven Falcon arrived on site equipped with a Remotely Operated Vehicle (ROV) to investigate 24 hours after the sheen was spotted.
A Reposl Sinopec spokesman said that no evidence of a leak was found but that investigations remained “ongoing”.
The Montrose and Arbroath platforms are located 200km east of Aberdeen.
They are part of the Montrose Area Redevelopment (MAR), which will unlock an additional 100 million boe (barrel of oil equivalent) of reserves and extend the life of the Montrose Area to beyond 2030.
MAR involves significant modification and expansion of the existing Montrose Area infrastructure, including the development of three new fields – Godwin, Cayley and Shaw.
The Montrose Alpha is one of the North Sea’s oldest platforms. It was installed in 1976.