North America, once a sponge that sucked in a significant portion of the world's oil, will instead be supplying the world with oil and other liquid hydrocarbons by the end of this decade, according to ExxonMobil's annual long-term energy forecast. And the "almost unspeakable" amount of natural gas found in recent years in the U.S. and elsewhere in North America will be enough to make the region one of the world's biggest exporters of that fuel by 2025, even as domestic demand for it increases, according to Bill Colton, Exxon's chief strategist.