The Bakken Shale is situated within the Williston Basin, which is located between the states of North Dakota, Montana and the Canadian province of Saskatchewan (see Bakken Shale map below). Oil in the Bakken Shale formation was first discovered back in 1951, but like other shale formations, the Bakken wasn’t a viable source of hydrocarbon production until recently because of the difficulty in extracting oil using conventional drilling methods.

Bakken Shale Map; Source: US Energy Information Administration

The Bakken is composed of three shale layers: the upper shale, middle dolomite and lower shale. The middle layer is the most productive layer for hydrocarbon production and is located at a depth of around 10,000 feet.

Directly below the Bakken Shale formation, there is a 270-foot thick formation known as the Three Forks-Sanish Formation. For some time, drillers believed that the Three Forks-Sanish Formation only contained oil that seeped out of the Bakken Shale. However, recent drilling results suggest that the Three Forks-Sanish Formation is a separate oil-bearing formation that could contain hydrocarbon resources rivaling those of the Bakken Shale. The prospect of having two layers of independent oil-producing formations has been an encouraging discovery for producers, who now stand to benefit from not one, but two productive formations on their properties.

Stratigraphic Column of the Williston Basin; Source: Energy Strategy Partners

As with other shale formations, the Bakken’s boom in oil and gas production resulted from advances in drilling technology. Hydraulic fracturing and horizontal drilling techniques have enabled oil and gas producers to economically extract hydrocarbons from rock formations that are not porous enough to be drilled conventionally.

Thanks to the evolution of these technologies, oil production in the Bakken has grown rapidly. For example, oil production in North Dakota has grown from less than 100,000 barrels of oil per day in 2003 to over 550,000 barrels of oil per day in 2012. North Dakota’s Department of Mineral Resources estimates that the state’s portion of the Bakken formation alone could hold more than 167 billion barrels of oil (see map below). Based on present technology, there are estimates that producers could extract between two and 11 billion barrels of oil from North Dakota’s portion of the Bakken Shale.

Bakken Shale Map of Original Oil in Place (OOIP) Estimates; Source: North Dakota Department of Mineral Resources

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