By Jonathan Stempel NEW YORK (Reuters) – A U.S. appeals court on Friday said Exxon Mobil Corp and Royal Dutch Shell Plc affiliates may try to enforce part of a $1.8 billion arbitration award against Nigeria’s state-run oil company, in a dispute concerning oil extraction near the African country’s coastline. In a 3-0 decision, the 2nd U.S. Circuit Court of Appeals in Manhattan said a lower court judge erred in rejecting the entire October 2011 award, which by 2018 had grown to $2.67 billion including interest, against Nigerian National Petroleum Corp. It said the judge should have determined wh…