In recent years, North Dakota's Bakken formation was synonymous with boom times. Crude production grew 10 times over, unemployment fell to a national low, and the state budget more than doubled as North Dakota's coffers grew fat on severance and sales tax income.
But with crude prices down more than 70 percent at their recent bottom, some of the drillers who fueled the boom are pulling back from the Bakken.
Several exploration and production companies are no longer completing wells in North Dakota and are now turning to more efficient assets in other states. Analysts say the decision comes down to a number of factors, from the geology of the Bakken to incremental costs that producers once overlooked but can no longer ignore.
Continental Resources, the company that put the Bakken on the map, said last month that it had stopped completing wells in the formation, and Whiting Petroleum announced it would stop fracking there by April. Last October, Occidental Petroleum sold all of its Bakken assets to private equity firm Lime Rock Resources.
Hydraulic fracturing, or fracking, is the process of breaking up shale rocks by bombarding them with water, minerals and chemicals at high pressure. The process can account for up to two-thirds of the cost of a well.