(Adds detail on repair options)
LONDON, Dec 19 (Reuters) - The timeframe to repair Britain's Forties crude oil pipeline in the North Sea remains two to four weeks, its operator Ineos said on Tuesday, adding that repair options were still being assessed.
The system, which carries around 450,000 barrels per day of Forties crude to Britain, along with a third of the UK's total offshore natural gas output, has been closed since Dec. 11 after a crack was found.
"The timescale stays the same - two to four weeks from the 11th," Ineos spokesman Richard Longden said.
He added that the company was examining three repair options.
In a news release issued on Tuesday morning, Ineos said that custom parts for some of these options had been made and would be delivered "over the coming days".
The Ineos-operated Grangemouth refinery shut down about half of its 200,000 bpd capacity on Friday owing to the pipeline outage. (Reporting by Alex Lawler and Julia Payne; editing by Louise Heavens and Jason Neely)