About Abiotic Oil
Now, a cursory search will find a lot of people arguing hotly around the issue, but very few talking of it. More in detail, Internet debates rarely touch the science involved: the explantion of how it may happen that those chemical reactions go in the opposite direction of what we can see at STP (standard pressure and temperature).
The "stock" explanation is that high pressure makes the production of abiotic oil possible, but few details are available. What abounds instead is conspiracy and other whacked-out theories about why abiotic oil is kept hidden, and rants against Big Oil and evolution and Obama etc.
Finally, with some more research I was able to obtain some solid science. One of the main figures in the abiotic oil camp is Vladimir Kutcherov (often misspelled as Kutherov) who is currently working at the KTH Royal Institute of Technology in Sweden. The basic work is laid out in the paper The evolution of multicomponent systems at high pressures: VI.The thermodynamic stability of the hydrogen–carbon system: The genesis of hydrocarbons and the origin of petroleum. This contains theoretical modelling of the H-C system (hydrocarbons) and experimental results from a special apparatus built to investigate reactions at high pressure and temperature. According to this paper, at 50 kbar and 1500 °C, starting only from wet calcium carbonate and iron oxide, alkanes up to C10 and alkenes up to C5 were produced.
Another article dealing with the subject, but with only abstract available, is Methane-derived hydrocarbons produced under upper-mantle conditions.
What to say, Kutcherov does not look like a crank, and his work sound, at least under a cursory examination.
There is a point I'd like to stress, tho: even if abiotic oil is real, and plentiful, it does not mean that it is produced at a rate sufficient to cover consumption; moreover the eventual abiotic oil is predicted to exist at considerable depth, making its extraction difficult, expensive and resource-consuming.