The U.S. consumes about 20 million barrels (3,200,000 m³) daily. If the Arctic
National Wildlife Refuge oil reserves were used to supply 5% of the U.S. daily
consumption -- most is imported from Canada (19%), Mexico (15%), Saudi Arabia
(11.5%), Nigeria (10.5%) and Venezuela (10.5%)[11] -- the reserves, using the
low figure of 4.3 billion barrels (680,000,000 m³), would last approximately
4300 days, or almost 12 years. Using the high estimate, the reserves would last
approximately 11800 days, or 32 years. Total oil independence at 20 million
barrels per day (using the before mentioned 10.5 billion barrel mean) would only
supply the United States for 525 days (or less than a year and a half, but this
complete supporting is impossible). Using the increasing price of oil this
supply (with 10.5 billion barrel mean and crude oil at over $120 a barrel) would
be worth 1,260,000,000,000.00 ($1.26 trillion).
]
But it would be sold on the world market, almost none of it would be
used by the US.

Saudi Arabia has ~ 264 billion barrels of reserves, about 34.5 times as much,
and produces around 9.2 million barrels per day. The world uses about 86 million
barrels per day so that entire estimated reserve compares to only about 90 days
worth of world use. Not that much though Exxon & others would be happy
to sell it.

There is an untapped 100 Billion barrel oilfield in the Dakotas.
We have known about it since the 1950s. May be double that amount.

http://www.kiplinger.com/businessres...er_080317.html