A good insight on what portion of oil prices is speculation and which is coming from demand, can also be obtained from examining the oil prices vs gasoline price. In the USA the vast majority of oil is used for transportation. And out of that the vast majority is gasoline (as in what you put in your car). So if the oil prices are going up but the demand or the prices of gasoline are not, it is fair to assume that the increase of oil prices is at least not due to underlying economic reasons.

Below is the gasoline demand and the gasoline (per gallon) futures.