If you really want to know, here is a good presentation on what are the key drivers and who and what are the major productions and consumptions of oil. Note those countries, get their economic data such as PMI, consumer sentiments, building permits etc.. and to forecast their next 3 to 6mths economic performance. All these information are freely available if you know how to search.
http://www.slideshare.net/TradeCruiser/oil-trading-fundamentals-module-1
The big players have all these data and reports and they already knew 3 to 6 mths ago, what is going to happen based on their leading fundamental indicators and already prepared if not already built their position before the current situation played out. If you want to speculate oil, you will have to do the same in order to be on the same boat as them and not a gambling bet that will lose your pants.