How North Dakota Became Saudi Arabia - Stephen Moore

http://online.wsj.com/article/SB10001424052970204226204576602524023932438.html

If he's right, that'll double America's proven oil reserves. "Bakken is almost twice as big as the oil reserve in Prudhoe Bay, Alaska," he continues. According to Department of Energy data, North Dakota is on pace to surpass California in oil production in the next few years. Mr. Hamm explains over lunch in Washington, D.C., that the more his company drills, the more oil it finds. Continental Resources has seen its "proved reserves" of oil and natural gas (mostly in North Dakota) skyrocket to 421 million barrels this summer from 118 million barrels in 2006. 

I'd knock a bit off the amount of oil available, and it will not displace OPEC, but discovering a LOT of oil in a place like North Dakota is still a big deal.