Sorry Dino, Oil Comes From Rock

Abiogenic Petroleum Origin

The abiogenic hypothesis argues that petroleum was formed from deep carbon deposits, perhaps dating to the formation of the Earth. Supporters of the abiogenic hypothesis suggest that a great deal more petroleum exists on Earth than commonly thought, and that petroleum may originate from carbon-bearing fluids that migrate upward from the mantle. The presence of methane on Saturn's moon Titan and in the atmospheres of Jupiter, Saturn, Uranus and Neptune is cited[1] as evidence of the formation of hydrocarbons without biology.[2]


The linked article in Wikipedia has perhaps the most balanced review of this topic. But beware, there is a lot of wack-job opinion masquerading as fact on this topic.