Forties diffs sank to their lowest in nearly two years last week, despite record flows to Asia and strong European demand that have helped draw down an overhang of some 10 million barrels that was stored on ships alone.
US demand has not been as strong for North Sea crude so far this year as it was last year.
According to Thomson Reuters Eikon trade flows data, some 4.5 million barrels of North Sea crude have crossed the Atlantic, compared with over 6 million barrels between January and May 2016.
Reuters shipping data shows Suncor has booked the Minerva Astra to load Brent crude at Sullom Voe, bound for Maine.
Statoil has booked the suezmax Delta Poseidon to take on Norwegian crude at Sture, where Oseberg and Statfjord typically load, bound for the US market.
In flows east, Total's shipping arm has booked the Atlantas to laod Forties at Hound Point in the first week of June.