The buildup, “amid the upward trend in US crude oil production, could be a bearish factor for oil prices in the coming few weeks,” the report said. OPEC’s assessment came as Brent crude, the global oil benchmark, fell below the $80-a-barrel threshold for the first time in nearly a month on Thursday, after data showed an unexpected rise in U.S. inventories. Late Thursday afternoon, light, sweet crude for November delivery was 0.9% lower at $69.14 a barrel on the New York Mercantile Exchange. Brent crude was 0.3% lower at $79.78 a barrel. At a meeting last month , the cartel and its allies debated how much they should open up their spigots to make up for Iranian oil exports , which will fall under a U.S. ban next month . But while Saudi Arabia and Russia have boosted output, some OPEC officials are worried about a global oil surplus. […]