Just How Big A Deal Is The Bakken? -- Pretty Big -- December 14, 2015

This is from the EIA:

The EIA continues to expand its assessment of technically recoverable shale oil and shale natural gas resources around the world. 

The addition of four countries—Chad, Kazakhstan, Oman, and the United Arab Emirates (UAE)—to a previous assessment covering 42 countries has resulted in a 13% increase in the global assessed total resource estimate for shale oil and a 4% increase for shale gas. 

A total of 26 formations within 11 basins were analyzed in these 4 countries. Of the eleven basins, one is the Williston Basin.

Although the formations in the newly added four countries (Chad, Kazakhstan, Oman, and UAE) contain significant volumes of technically recoverable resources, there is currently no shale exploration underway in any of the four countries, meaning the new assessed resources are not yet economically recoverable. 

The portions of these resources that become economically recoverable in the future will depend on crude oil and natural gas market prices, as well as the capital and operating costs and productivity within the countries. Each of the countries has an existing oil and natural gas industry with infrastructure connecting the basins to global markets. All current production of oil and natural gas in Chad, Kazakhstan, Oman, and the UAE is from non-continuous resources (from high-permeability formations). 

However, only four countries (the United States, Canada, China, and Argentina) are currently producing oil and natural gas from these resources at commercial scale, with the United States alone providing 4.4 million b/d, or more than 90%, of global tight oil production and 42 Bcf/d, or more than 89%, of global shale natural gas production.

Again, from tight oil, the United States accounts for more than 90% of global tight oil and most of that comes from three plays: the Permian, the Eagle Ford, and the Bakken.