Oil drillers have their eye on a vast oil field in and around North Dakota, which promises a steady flow of domestic crude for years. A new black gold rush is under way, this time in North Dakota. The potential payoff is huge -- up to 100 billion barrels of oil. That’s twice the size of Alaska’s reserves and potentially enough to meet all U.S. oil needs for two decades. Until now, the obstacles to production seemed overwhelming. The crude oil is locked away in rocks that are buried miles underground in the Bakken Play, a field that stretches into...