According to the licence terms, the earliest date when a transfer of the Statfjord operatorship could take place was 7 August 1984. That was 10 years after the field had been declared commercial.
More about history
President Carter visits Statfjord A
It is not every day that Norway gets a visit from an American president, but 4 May 1982 was one such occasion. That was when Jimmy Carter and his wife Rosalyn took a trip out to Statfjord A, which was operated at the time by Mobil Exploration Norway Inc (Meni).