A Bismarck company is planning a 100-mile-long pipeline to carry natural gas from the Bakken shale formation in North Dakota and Montana to an existing pipeline that moves the gas to Chicago.

Williston Basin Interstate Pipeline Co., a unit of MDU Resources Group Inc., hopes to have the pipeline completed in mid-2010, said Tim Rasmussen, a company spokesman.

The announcement was made on Monday by the pipeline's parent company, WBI Holdings Inc.

The pipeline's cost is pegged at between $50 million and $75 million, and it initially will carry 100 million cubic feet of natural gas daily, or enough to power about 400,000 homes in a year, Rasmussen said. The pipeline's capacity is 200 million cubic feet daily, he said.

The 16-inch pipeline will originate and connect with Williston Basin's existing pipeline system near Tioga in the northwestern corner of North Dakota, Rasmussen said. It will connect with the Alliance Pipeline Ltd.'s pipeline in Bottineau County, near Antler, about 10 miles from the Canadian border, he said.

Alliance Pipeline is a 2,300-mile pipeline system that extends from northeastern British Columbia and northwestern Alberta to the Chicago hub, where the gas is sold to Midwest and East Coast markets.

"The Alliance Pipeline comes through the heart of North Dakota," Rasmussen said. "This provides another market outlet for gas being produced in the Bakken."

The government estimated last month that up to 4.3 billion barrels of oil can be recovered from the Bakken shale formation in North Dakota and Montana, using current technology.

The U.S. Geological Survey called it the largest continuous oil accumulation it has ever assessed.

The Bakken Formation encompasses some 25,000 square miles in North Dakota, Montana, Saskatchewan and Manitoba. About two-thirds of the acreage is in western North Dakota, where the oil is trapped in a thin layer of dense rock nearly two miles beneath the surface.

Ron Ness, president of the North Dakota Petroleum Council, said the pipeline would provide more markets for the liquid natural gas produced in the Bakken.

"A lot of the gas being produced now is trucked," Ness said. "This would eliminate truck traffic and provide a market for this high-value, rich Bakken gas."

Rasmussen said there are no plans to pipe the Bakken gas to markets in North Dakota.

Montana-Dakota Utilities, another MDU subsidiary, has about 85,000 natural gas customers.

The utility serves most of North Dakota's largest cities, including Bismarck, Dickinson, Devils Lake, Jamestown, Mandan, Minot, Valley City and Williston.