Exxon Mobil Corp. is cutting its drilling budget to a 10-year low and halting share buybacks after last year’s belt-tightening failed to shield the world’s biggest oil explorer from crashing energy markets. On the heels of its smallest annual profit since 2002, Exxon said it’s curbing its spending on rig leases, floating oil platforms, gas terminals and other projects by 25 percent this year to $23.2 billion, according to a statement on Tuesday. That represents the leanest spending plan since 2007, the second year on the job for Chairman and Chief Executive Officer Rex Tillerson. Share buybacks that cost the Irving, Texas-based company half a billion dollars during the final three months of 2015 also have been suspended. Tillerson, who reaches Exxon’s mandatory retirement age of 65 in 13 months, has been reducing spending since before the crude-market collapse that began in mid 2014 as the company’s costliest mega-projects […]