Big U.S. oil companies are starting to think small. A stubborn 16-month crude rout with no end in sight is driving the largest U.S. oil producers away from costly, high-risk megaprojects long touted as the industry’s future and toward safer shale operations that generate the cash needed to satisfy anxious investors. Exxon Mobil Corp., Royal Dutch Shell Plc, Chevron Corp., ConocoPhillips and Hess Corp. have all either delayed or abandoned projects that range from the deep seas of the Gulf of Mexico to Canada’s oil sands and the U.S. Arctic. At the same time, Exxon and Chevron both announced plans to substantially increase U.S. crude production, largely as a result of their shale operations. “What makes more sense in this environment: drill a $100 million well in the deepwater Gulf that might come up empty, or poke lots of holes in west Texas where you already know there’s oil […]