Infrastructure constraints shouldn't inhibit production from oil-producing basins in North Dakota, analysis from Wood Mackenzie finds.

Energy consultant group Wood Mackenzie said it expects production from the Bakken and Three Forks areas, two fields situated in the northern Williston Basin, should produce a combined average of 1.1 million barrels per day this year.

The Bakken field is now producing more oil than any other unconventional play in the world, the group said Wednesday, and industry officials said the output from the entire region is straining existing pipeline capacity.

"We do not believe infrastructure constraints will impact the pace of the play's development," the analysis finds.

More than 70 percent of the crude oil leaving the region is delivered by rail.

About 950 barrels of oil spilled in North Dakota when two trains operated by BNSF Railway collided and derailed in a January accident

The Pipeline and Hazardous Materials Safety Administration issued a safety alert in early January saying the type of crude oil in the Bakken reserve area in the state may be more flammable than other grades.

U.S. safety regulators said older DOT-111 cars, some of which were involved in recent derailments, may be more vulnerable to leaks or explosions than other types of rail cars.