the chemistry of oil and NG requires pressure and heat same as that needed to form coal and diamonds. the biggest deposits are found in coastal areas miles below the surface where you find many forms of rock strata...I will look at the geological data for evidence..., I am not saying that plankton and sea life could not add to the equation , it is a complicated process, and a simple statement that dinosaur and plant life is the source is very self serving...
The fact that other planets or moons in our own Solar System, proven not to support life as we know it, yet still produce Oil and Gas in abundance...Titan, proves my point, as other have noted, Organic life or man was not needed, only the Creators Chemistry Set.
I will look for the original white paper research I studied about 15 years ago, it is here on one of my computers???