Said to be the first-of-its-kind refinery in the US, the complex is built with an investment of around $435m.
The companies have started diesel production at the complex, and expect to commence sales soon.
MDU Resources president and CEO David Goodin said: "With more than two-thirds of North Dakota’s diesel fuel currently imported into the state, the Dakota Prairie refinery is well positioned to meet strong regional demand with additional, locally produced supplies of diesel fuel.
"Over time, we expect that this refinery has the potential to be an important contributor to the economic growth of the local and state economy."
The refinery is designed to process about 20,000 barrels per day (bpd) of locally sourced Bakken crude oil, to produce 7,000bpd of diesel, up to 6,500bpd naphtha, up to 6,000bpd of atmospheric tower bottoms, and other refined products.
