For months, the oil market has been bracing itself for a looming large oversupply. Forecasters, investment banks, and analysts expect the overhang to depress oil prices at the end of this year and early next year as inventory builds begin to show up at the key pricing hubs. The consensus appears to be that a glut will soon overwhelm the market. But estimates on how big the overhang will be vary, ranging from a super-glut of record proportions to more modest inventory increases in the historically weaker demand period in the first quarter…