There has barely been any such research because of the difficulty and expense of the work.
The Left has decided we must, MUST, they say, run out of oil. The science is settled.
Settled science says that this nasty hydrocarbon that selects minority groups, women, and the LGBTG Community for grievous physical harm, is terrible for Our Green Mother Gaia. It is indeed fortunate that we will run out of the stuff on November 3, 2016 because of George Bush.
It is just downright embarrassing that this foul germ-laden stuff keeps turning up everywhere, even under wind generation plants!