The U.K.'s BP is selling off assets as it is still in the midst of trying to pay for damages from the 2010 Gulf coast oil spill.
The companies said Monday that the properties were producing an estimated 59,500 barrels of oil equivalent net per day as of July's end.
Plains also announced that it is buying a 50 percent working interest in the Holstein Field from Shell Offshore Inc. for $560 million. The properties were producing an estimated 7,400 barrels of oil equivalent net per day at July's end.
Both deals are expected to close by the end of the year.