ENERGY

Mobil to Swap Service Stations: Mobil Corp. said it would swap its 90 Houston-area service stations for 16 Shell Oil Co. service stations in Milwaukee and an undisclosed amount of cash. As a result, Mobil will withdrawal from motor fuel sales in the Houston market and Shell will pull out of Milwaukee entirely. Terms of the transaction were not disclosed. Completion of the swap is scheduled for May, 1992.