Delta Air Lines through a subsidiary company agreed to acquire from Phillips 66 a Philadelphia-area oil refinery.

Delta subsidiary Monroe Energy, which plans to close the transaction by the end of June, will invest $250 million in the acquisition, refinery improvements and related sourcing and marketing agreements with Phillips 66 and BP. Delta plans to double the refinery's jet fuel production, eventually supplying 80 percent of its domestic fuel needs. The carrier estimates its refinery ownership will save $300 million in annual fuel expenses and reduce its "exposure to fuel volatility."