Link here.
Yes, unfortunately, Virginia, there is no Santa Claus.
And, unfortunately, Virginia, the Bakken thins out.
This thread includes a link to a USGS Fact Sheet dated April, 2008.
That report is linked somewhere on my site; probably in several places.
2008? Perhaps time for an updated assessment.
This is probably the best site you will ever find on the geology of the Bakken. Smile. And it's all free.