There are at least two physical-chemical tests that prove that nearly all of the oil that has been commercially exploited to date has a biological origin:

• isotopic profiles match those of decayed biological materials grown on the surface of the earth,
  
• isomery of carbons in the C-strings of oil are largely dextrogyrous, just like in the proteins of living animals, which have amplified and maintained an original asymmetry whose origin is unknowns, but which doesn't exist in non-biologic chemistry.
  

I can certainly understand that some deep geological formations could yield hydrocarbons of non-biological origin, and we may someday find them and be able to recognize them for what they are. But it has just not happened yet, all those who have claimed so were just lying for reasons of dishonesty or ideological antagonism (remember Lyssenko ?).

This fact alone doesn't bode well for the business prospect of abiotic oil, not to mention as a savior of mankind !

Also, biotic oil is already hard to retrieve at the depths where we still have some. Deep crust abiotic oil would be even harder to locate and extract, making shale oil and the likes a piece of cake...

Pierre