Now that Royal Dutch Shell Plc has made its move for BG Group Plc, Exxon Mobil Corp. and BP Plc could contemplate deals — perhaps even with each other. Speculation of an Exxon-BP combination surfaced last year after oil prices declined sharply, increasing the appeal of big mergers that could yield massive cost savings. BP has largely put behind it the legal morass surrounding the 2010 Gulf of Mexico spill. Still, the $124 billion company remains among the cheapest major producers relative to estimated profit, according to data compiled by Bloomberg. There are, of course, other targets for Exxon and BP that have gotten less expensive in recent months. Anadarko Petroleum Corp., Cabot Oil & Gas Corp., Pioneer Natural Resources Co., Occidental Petroleum Corp. and Tullow Oil Plc are among those that have risen to the top of analysts’ lists. Their market values span Tullow’s $4.2 billion to Occidental’s […]