Demand had been increasing since the bottom of the great recession. This started last June with the dollar lifting off (pushing commodities down and crashing emerging markets), and the Saudis deciding to try to retain market share and crush the booming US oil production. So now, despite $40-$60 oil, the Saudis are producing the most oil they ever have. US oil companies have managed to constantly reduce the cost of their oil, with frackers getting it down to $40 to $50 / barrel, the US will produce almost a million barrels per day more than in 2014 despite the price drop. On top of all of that, the market is front running both Iran bringing its oil online again, and the Fed raising interest rates and sending the dollar higher.