The russians/ukranians have never bought the fossil fuel explanation for oil and posited the deep earth natural process instead. The problem with the fossil fuel theory is how does all this plant matter die, but not decay, and then find itself under enormous pressure to turn to oil? Pretty much anything that dies ultimately decays long before it could be preserved in mud or earth. The rate of top soil rich in dead plant matter being consumed to inner earth seems a bit far fetched.
A couple have pursued this claim. But commercial production of oil, like in the rest of the world, is located on traditional geological research, and only found in sedimentary rock. I've been on the design team of Siberian Oil fields.