The Loma Campaña Vaca Muerta shale oil drilling site in Neuquén, Argentina. Shale producers are roaring back to life, pushing the global oil supply to its highest level in a year and undermining OPEC’s efforts to rebalance the market through production cuts, the International Energy Agency said Thursday. In its closely watched monthly oil market report, the IEA said the amount of crude oil on the global market rose by 170,000 barrels a day in November to 97.8 million barrels a day. The agency cited a surge in U.S. shale production and increased drilling and completion activity. The report comes just two weeks after the Organization of the Petroleum Exporting Countries and 10 producers outside the cartel, including Russia, agreed to extend curbs on production through the end of 2018 . The group first agreed a year ago to cut almost 2% of global oil production in an effort […]