However, you'll play hell trying to convince anyone of that. That methane, common throughout the solar system, will combine with water, and under high heat and high pressure, be converted?
That these hydrocarbons, seeping up from the Mantle, are trapped by certain geologic formations, mostly sedimentary, like buried swamps, sand bars, salt domes? That these organics contaminate the petroleum, so that some are high sulfur, some are sweet, some are sour, or even are solids, like coal fields?
That so called "exhausted" wells are slowly refilling? That "Peak Oil" is as stupid a belief as seances and astrology?
I've seen no studies showing anything other than very slow refilling. Much much slower than pumping it out.
You need a lesson in hydrocarbon generation and migration. I doesn’t come from the mantle. It is a little too warm there.