Calgary-based Enerplus Corp. on Dec. 21 sold part of its nonoperating interests in North Dakota for approximately $80 million, as it plans to concentrate on operating assets in the Bakken on the Fort Berthold Reservation lands. The interests that were sold amount to less than 2% of Enerplus’ net acreage in the state. The proceeds will be used to reduce outstanding bank debt for the oil/natural gas developer, which is involved in plays on both sides of the U.S.-Canada border. Enerplus’ Fort Berthold operations amount to about 85% of its current production in North Dakota.