The ingenuity and easy money that allowed American oil companies to keep pumping through a year-long price crash appear to be petering out as U.S. crude slides toward $40 a barrel. U.S. companies have stunned global rivals by continuing to produce oil —particularly from shale deposits—ever more cheaply as American crude prices plunged from over $100 a barrel in 2014. But the recent drop toward $40 a barrel and below puts even the most efficient operators in a bind. The worst-case scenario most major producers have discussed in the past six weeks with investors involved a price of $50 a barrel. That is beginning to look optimistic as Saudi Arabia continues to produce near-record volumes and major exporters such as Iraq have increased output. Many oil executives, including BP BP -2.33 % PLC CEO Bob Dudley, expect prices to be “lower for longer.” The U.S. Energy Department is forecasting […]