The Bakken Formation is a massive shale formation in the northern Midwest of the United States. In 2013, the United States Geologic Survey reported that the Bakken group of oil fields may contain at least 3.65 billion barrels of oil, plus additional natural gas and liquid gas reservoirs.
The Bakken Formation is part of the larger Williston Basin and includes parts of North Dakota, Montana and southern Canada. The basin dates from the paleozoic era, or approximately 360 million years ago. The formation is composed of upper and lower black shale layers with dolomite in between. Its name derives from the original property owner, Henry Bakken.
According to the University of North Dakota Energy & Environmental Research Center, the Bakken Formation was discovered in 1953 by geologist J.W. Nordquist. Standard Oil and Gas first produced oil from the area in 1955, followed closely by Shell Oil in 1961. Development did not accelerate until after the advent of horizontal drilling in the 1990s. In 2000, there were only approximately 10 oil rigs in the fields, with a total average production of under 100,000 barrels per day. Ten years later there were 126 oil rigs and average production had more than tripled.