North Dakota regulators on Tuesday ordered producers pumping oil from the Bakken shale field to begin removing flammable natural gas liquids from their product before shipment in an effort to prevent deadly explosions involving trains.

The Bakken field has played a major part in the spurt of oil drilling that has raised domestic production by more than 70 percent over the last six years. But a series of explosive accidents involving trains carrying Bakken crude, including one last year in Quebec that took 47 lives, has raised fears in many cities where oil trains regularly transit.

Oil companies rely on the trains because the Bakken shale field has been developed so quickly and adequate pipelines do not exist in and around North Dakota.

The new regulations set by the North Dakota Industrial Commission will require producers of Bakken crude to process their product through mandated temperatures and pressures that regulators hope will remove much of the butane, propane and other volatile liquids commonly found in the North Dakota crude.