Plans call for Statoil's Yme field in the North Sea to cease production late this year or in early 2001.
An average output of 27,000 barrels per day in 1999 was lower than planned, according to Geir Pettersen, senior vice president for production operations.
"We're now keeping a careful eye on oil prices to determine when Yme should be shut in," he says.
Persistently high prices could extend production some way into 2001.
Statoil is still making money on Yme, which is the smallest field developed off Norway with stand-alone production facilities.
By 31 December, it had yielded 43 million barrels of oil – twice the volume forecast by the group when Yme came on stream in February 1996.
Mr Pettersen expects about 7.5 million barrels to be recovered from the field during the present year.