The shutdown of Britain's largest crude oil pipeline is an early Christmas gift to U.S. exporters shipping to Asia, and a complication for Middle Eastern and African producers seeking to maintain market share in the world's top importing region. The Forties Pipeline System, which carries about 450,000 barrels per day (bpd) from the North Sea to Scotland, may be closed for several weeks for unscheduled repair work, operator Ineos said on Monday. Forties crude is the largest of the five North Sea crudes that make up the dated Brent price benchmark. Brent crude futures jumped 2 percent on Monday to settle at $64.69 a barrel, their highest in 2-1/2 years. But given the price spike is related to an actual physical supply issue, the price of competing U.S.