At slide 17, the USGS provides a graphic of the relative size of the various basins of continuous oil reservoirs, such as the Bakken, in the United States, to include Alaska. If one is trying to downplay the size of the Bakken, this is pretty successful.
Each basin/locality has a green "dot" varying in size based on the size of the reservoir. The USGS uses four dots to represent four "sizes":
- less than 0.1 billion bbls
- 0.1 to 0.5 billion bbls
- 0. 5 to 2.0 billion bbls
- greater than 2.0 billion bbls
Take a look at the graphic (slide 17 at the link). There is not a whole lot of difference in the size of the green "dots" for the Permian, the Western Gulf, and the Williston Basin. In fact, a newbie glancing quickly at this one slide would not be all that impressed with how much bigger the Williston Basin is compared to the Permian or the Western Gulf based on the graphic or the size of the dots.
But then look at the numbers:
- Permian Basin (Midland-Odessa): 0. 51 billion bbls
- Alaska North Slope (Prudhoe Bay): 0.94 billion bbls
- Western Gulf (Eagle Ford) Basin: 1.73 billion bbls
- Williston (Bakken/Three Forks) Basin: 7.38 billion bbls
Having said all that: my hunch is that the estimate for the Western Gulf (Eagle Ford) continuous reservoir is significantly underestimated, and will be revised upward in the next assessment.