In a new update to its drilling productivity report from last week, the Energy Information Agency said North Dakota's Bakken and Texas' Permian Basin and Eagle Ford Shale are quietly generating more than a million barrels of oil per day each–comprising at least a third of total U.S. daily oil production. Shale oil drilling generated the equivalent of nearly 90 percent of the U.S.'s total energy needs in 2013, according to EIA figures.
Mark Perry, an economist at the University of Michigan and a scholar at the American Enterprise Institute, crunched the EIA's numbers even further. His analysis suggests the output of the combined three oil fields is actually exceeding 4 million bpd, which would make them the world's fifth largest oil producer by volume.
"In all of human history, there have only been ten oil fields in the world that have ever reached the one million barrel per day milestone," the economist wrote in a recent blog post. "Three of those ten are now active in the US–thanks to the advanced drilling techniques that started accessing oceans of shale oil in Texas and North Dakota about five years ago."