The Organization of the Petroleum Exporting Countries kept its production ceiling unchanged Wednesday despite the threat of rising supply that could weigh on prices. For the better part of a year, members of OPEC, a cartel of some of the world’s biggest oil producers, has been studying the possible market effects of increasing North American output. But now, the threat of surging supply from OPEC members themselves looms. The cartel pumps more than one in three barrels of crude consumed globally and uses its production ceiling, currently at 30 million barrels a day, to keep prices in check. But as its meeting here wrapped up, members didn’t express any consensus on what—if anything—the group would do about the prospect of new output from Iraq, Iran and Libya. Iraq now is producing more annually than it has in at least the last 20 years–and has shown little appetite to throttle […]