look at a one minute chart with volume if you see 1,000.000 shares print a minute then there is some real volume going on. Could be anything big fund getting out of a trade, mm cleanup etc.
what he said, to the op you may want to read this, feel free to disagree. Basic premise is that there is an institutional bid to that market.
http://www.amazon.com/Oils-Endless-Bid-Unreliable-Economy/dp/0470915625