I believe I have posted this screen shot previously; if not, I have certainly discussed it. Not all pay zones are in every area of the North Dakota Bakken.
Note: The slide does not delineate the upper Three Forks and the lower Three Forks. The vast majority of "Three Forks" wells in North Dakota targeted the upper Three Forks. Only a handful of wells (CLR, KOG) have tested the 2nd, 3rd, and 4th benches of the lower Three Forks.
Be sure to double-click on the screen-shot to open it in another window. Note the millions of barrels of original oil in place per 1280-acre spacing unit. The recovery rate from the Bakken Pool is variously reported from 1% to 8%.