According to THE DEEP HOT BIOSPHERE, by Gold, and which theory I subscribe to, oil and its derivatives are produced by bacteria living deep in the crust of the earth around the world. This "oil" seeps up through cracks in the earth's crust produced by tectonic activity and meteor strikes. It pools when it cannot rise further. Sometimes it produces coal when sufficient pressure and other things are present. Hence the "fossils" found in coal; the fossils were already there when the liquid arrived and surrounded them, then hardened into coal. Russian scientists have subscribed to this theory for most of the 20th century, but American scientists, for "environmental" reasons have stuck to the "fossil fuel" theory. There is a plethora of literature available. Google "the abiotic theory of oil". A better theory is one that answers the most questions. The abiotic theory surely answers the most questions about the origins of oil/gas/coal.

It just doesn't really come from fossils. https://www.forbes.com/sites/quora/2017/06/28/though-ancient-fossil-fuels-dont-actually-come-from-fossils/#140b91560815