As Exxon Mobil Corp. (XOM) and Royal Dutch Shell Plc, the world’s largest oil companies, bet on increasing production from Russia, smaller rivals are boosting crude supplies by exiting foreign fields to focus on booming U.S. wells. ConocoPhillips, Occidental Petroleum Corp. (OXY) and Apache Corp. reported rising second-quarter output as they divest international assets. Nationwide, U.S. oil production is at a 25-year high because of advanced drilling techniques that cracked petroleum-rich shale formations. Meanwhile, Exxon’s shares fell the most in almost three years after reporting quarterly oil and natural gas output decreased 5.7 percent to the equivalent of 3.84 million barrels a day, the lowest since the third quarter of 2009, according to data compiled by Bloomberg. Exxon is searching Russia ’s Arctic seas for crude as part of a global effort by the Irving, Texas-based company to halt a trend of declining output. “Exxon and companies of similar […]