WASHINGTON -- U.S. oil production has soared to heights not seen in 20 years, largely driven by an explosion in crude harvested from Texas shale rock.America is producing more than 7 million barrels of oil a day, the highest volume since 1992, according to figures released Thursday by the U.S. Energy Information Administration. It's another sign of the transformation of American energy, as the nation is forecast to overtake Saudi Arabia as the world's top oil producer in just a few years.Texas and North Dakota are the dominant states behind the increase in oil production, with crude from the Bakken formation of North Dakota transforming that state and allowing it to pass Alaska as the nation's second-leading oil producer.Since January 2010, Texas has doubled its crude production and is by far the U.S. oil king. It's mostly because of the Eagle Ford shale region in South Texas, said Philip Budzik, an EIA analyst. The energy revolution there and in North Dakota is a result of horizontal drilling techniques and hydraulic fracturing.Mark Perry, an economics professor at the University of Michigan-Flint and a visiting scholar at the conservative American Enterprise Institute think tank, said Texas has become "Saudi Texas."Texas now produces almost three times as much crude oil as the second-place state, North Dakota. Texas alone has accounted for nearly a third of U.S. oil output in the past six months, according to Perry. If Texas were a separate country, he said, it would rank above Norway as the 14th-largest oil-producing nation.Along with the booming Eagle Ford region, which just five years ago produced little oil, the Permian Basin in West Texas is seeing a drilling resurgence as oil is extracted from its shale rock.The unlocking of such reserves is a major reason the International Energy Agency forecasts the U.S. will become the world's leading oil producer by about 2017.