The Williston Basin was found to be productive in 1951 by the Amerada Petroleum Company, and the Bakken formation was formally described in the H.O Bakken No. 1 well in 1953. The Bakken formation is a mixed lithology clastic-carbonate system with poor reservoir rock quality, most of the early vertical wells other than the ones in the naturally fractured Antelope field were marginal. The robust development of the Bakken started mid-2008 and continued to see an upward trend in crude oil production until early 2015 when the play, at the time, hit peak production levels at around 1.2 million barrels-per-day (MMbbl/d). Due to shrinking crude oil prices, the Williston Basin and the Bakken/Three Forks crude oil production retracted slightly to 1 MMbbl/d of crude for most all of 2016. Since then, and with healthier oil prices, crude oil production in the Bakken currently is at peak level at 1.3 MMbbl/d.