BISMARCK, N.D. (AP) — Oil refineries in Mandan and Dickinson will be changing owners when Marathon Petroleum Corp. merges with Andeavor.

Andeavor was recently known as Tesoro. It employs 300 people at its two North Dakota refineries.

Marathon Petroleum is buying Andeavor for more than $23 billion, a transaction that would make the combined company the largest U.S. refiner. The combined company will have headquarters in Ohio and will be called Marathon Petroleum.

The Bismarck Tribune reports Andeavor also owns pipelines in North Dakota, natural gas processing plants near Belfield and New Town and a rail terminal at Fryburg. Marathon Petroleum owns an interest in the Dakota Access pipeline.

The merger is expected to close in the second half of 2018.