The Bakken formation is one of the highest-cost sources of U.S. oil production. Shown, workers… North Dakota crude-oil production fell for the fourth month in a row, dropping about 1% in March and hitting its lowest level in nearly two years. The steady drop in output comes amid a downturn in crude prices, which has cut into profit margins from wells in the Bakken formation in North Dakota and other U.S. shale-oil fields. Oil production in the state dropped to 1.10 million barrels a day in March from 1.11 million barrels a day in February, according to the latest data from the North Dakota Department of Mineral Resources. The state’s output hasn’t been that low since June 2014, and it marks the fourth straight month of declines, data from the department show. The Bakken formation is one of the highest-cost sources of U.S. production. The fall in oil prices […]