Midstream operator ONEOK Partners said it completed a pipeline in North Dakota that will help shale developers reach regional markets.

ONEOK, which has headquarters in Oklahoma, said an expansion of its Bakken NGL pipeline is completed, increasing the capacity by more than half to 135,000 barrels of unfractioned natural gas liquids, like butane and propane.

"The expansion of the Bakken NGL Pipeline reflects our continuing commitment to provide NGL transportation capacity to producers actively developing shale plays within our operating footprint," President and Chief Executive Officer Terry Spencer said in a Thursday statement.

North Dakota is among the top oil-producing states in the nation. Some of the natural gas associated with the shale oil deposits is burned off because of the lack of infrastructure needed to make it a commercial product.

ONEOK added its Garden Creek III gas processing facility in North Dakota was completed more than three months ahead of schedule.

"The Garden Creek III plant is the latest example of ONEOK Partners' ongoing commitment to building essential natural gas and natural gas liquids infrastructure to meet the needs of our customers," Spencer said.