A glut of crude may keep oil prices low for the next 15 years, according to Goldman Sachs Group Inc. There’s less than a 50 percent chance that prices will drop to $20 a barrel, most likely when refineries shut in October or March for maintenance, Jeffrey Currie, head of commodities research at the bank, said in an interview in Lake Louise, Alberta. Goldman’s long-term forecast for crude is at $50 a barrel, he said. Goldman cut its crude forecasts earlier this month, saying the global surplus of oil is bigger than it previously thought and that failure to reduce production fast enough may require prices to fall near $20 a barrel to clear the glut. Prices may touch that level when stockpiles are filled to capacity, forcing producers in some areas to cut output, Currie said Wednesday. “When we think of the longer term oil price, yes we […]