Shares of Whiting Petroleum Corp , Continental Resources Inc and other top crude oil producers in the Bakken shale formation plunged on Thursday after the U.S. government said oil produced there may be extra flammable. The warning came three days after a BNSF train carrying crude oil collided in eastern North Dakota with another train carrying grain. The resulting explosion led to the temporary evacuation of a nearby town and added to the growing concern about the safety of oil-by-rail shipments. Last July a runaway oil train, which originated in North Dakota, derailed and exploded in a small Quebec town, killing 47 people. Oil extracted from the Bakken, a vast rock formation underneath North Dakota and Montana, “may be more flammable than traditional heavy crude oil,” the Pipeline and Hazardous Materials Safety Administration, part of the U.S. Department of Transportation, said on […]