A decade ago, North Dakota was a wind-swept also-ran in the oil industry. Wildcatters struck oil there in the 1950s, but the rock was too dense to get most of it out, and the fields never amounted to much. The state produced about 30 million barrels of oil in 2004, enough to satisfy U.S. demand for about a day and a half. Then everything changed. In the mid-2000s, companies in Texas had figured out how to extract natural gas from dense shale rock near Fort Worth. A few enterprising oil men figured the same approach might work in North Dakota’s oil fields, and after a few false starts, they proved correct. Between 2004 and 2008, North Dakota’s oil production doubled. Then it doubled again. And again. This month, the Energy Information Administration said North Dakota produced 30 million barrels of oil in April — as much as it had […]