Why are oil prices staying down? I know OPEC production has not been reduced, but one would think that extra production would be needed to sustain low prices in the face of production losses.
Because global supply grew more than global demand. The US has begun to taper down the production rate from lack of investment over that past year. OPEC, Russia are producing more. Oil stocks are still high.
Global Petroleum and Other Liquids
http://www.eia.gov/forecasts/steo/report/global_oil.cfm
Global petroleum and other liquids production continues to outpace consumption, leading to inventory builds throughout the forecast period. Global oil inventory builds in the third quarter of 2015 averaged 1.6 million b/d, down from 2.0 million b/d in the second quarter, which had the highest level of inventory builds since the fourth quarter of 2008. The pace of inventory builds is expected to slow in the fourth quarter to roughly 1.2 million b/d. In 2016, inventory builds are expected to slow further to an average of 0.4 million b/d as global liquids output is expected to be unchanged from 2015. The 0.4 million b/d reduction in projected 2016 inventory builds from last month's STEO mostly reflects lower forecast oil production in Canada and the United States.
more at link, including charts