Hydrocarbons have been found in great abundance elsewhere in the solar system where there is unlikely to be evidence for life past or present. No fossils involved.
Petroleum and natural gas wells that have gone dry 50 years ago, are found replenishing a fraction of their output. No fossils involved.
Vast biomass of micro-organisms and extremophiles beneath earth surface estimated to be several times the size of the surface biomass found deriving their chemical energy for life from methane and oxygen pulled from sulfates and ferrous oxides. The source of methane way too deep to come from fossils. No fossils involved.
These recent findings and other evidence were foretold by the late scientist and researcher from Cornell, Thomas Gold, who authored "The Deep Hot Biosphere, The Myth of Fossil Fuels".
After seeing evidence of extremeophiles in relative abundance in even the deepest of mines, Gold ties the sub-surface biosphere to the "Deep Earth Gas theory" to show a more plausible primordial explanation of hydrocarbon fuel formation than the generally accepted "fossil" theory.
He posits that "Hydrocarbons are not biology reworked by geology (as the traditional view would hold), but rather hydrocarbons are geology reworked by biology." In other words, as in Saturn’s moon Titan and other hydrocarbon rich areas of the solar system, the source of hydrocarbons is primordial; but as they upwell into earth’s outer crust microbial life uses it as energy source.
While the details of the Deep Earth Gas Theory are beyond scope of elaboration in this question area, the main points which Dr. Gold supports, and provides evidence for are:
Hydrocarbons are primordial. IOW, hydrocarbons like elsewhere in the solar systems are here since the planet's birth.
The earth was subjected to only a partial melt.
Hydrocarbons are stable to great depth. High pressure greatly stabilizes hydrocarbons against thermal dissociation.
Rock at depth contains pores.
Primordial hydrocarbons are still upwelling from the deep earth.
some sub-points worthy of mention:
It more adequately explains why Helium is only present in the earth at any mine-able quantity in natural gas. There are no pure Helium wells. Why the strong association of hydrocarbons with Helium, an inert gas that can have no chemical interactions with fossil organic materials or with hydrocarbons? This is known to geologists as the "Petroleum Paradox" and cannot be explained at all by a sedimentary origin of hydrocarbons.
The presently accepted theory of fossil fuels is that the hydrocarbons formed from the decayed remains of ancient organic matter (fossils) that somehow sank down into the deep earth and got trapped in sedimentary rock formations where increased pressures assisted in converting the organic material over time to hydrocarbons.
Well, hydrocarbons are found in depths where no surface life remains could have possibly geologically submerged to. The physics of how the ancient organic materials or the resulting hydrocarbons sank deep into the earth have yet to be explained. Also, hydrocarbons have been found in igneous rock formations, which the accepted surface to sediment theory cannot explain.
Can we still say that fossil fuels are really from fossils?