The acquired assets will turn a profit even if crude prices dip as low as $35 a barrel, Exxon said. Exxon’s inventory of yet-to-be-drilled sites in the world’s biggest shale basin will expand, giving it access to a vast number of potential onshore wells that, unlike deepwater ones, can be brought online within months and make Exxon far more nimble at keeping pace with erratic global demand.