Mexico’s vote on rules for the end of its 76-year state-oil monopoly couldn’t come at a better time for global energy companies from Exxon Mobil Corp. (XOM) to Royal Dutch Shell Plc. With reserves holding $1.3 trillion of crude at yesterday’s prices, Mexico offers a new opportunity for deep-pocketed producers as well as pipeline and power companies to try and mimic an energy revolution that has spurred U.S. oil output to a 26-year high and pushed Canadian production to records.