BP states that the Prudhoe Bay oilfield has produced about 2 Billion barrels of oil and will produce another..?

1 Billion. Suppose that this 1 Billion barrels were to be the sole source of U.S. oil. How long will it last?BP states that the Prudhoe Bay oilfield has produced about 2 Billion barrels of oil and will produce another..?
The US currently consumes about 20 million barrels of oil each day so this would last about 50 days.