[crusty old prospector]

Oil is not usually found below 10,000’ except in “cool” basins, such as the Gulf of Mexico. At higher temperatures, the Earth acts like a refinery and cooks the oil into more volatile members, like methane, butane, etc... Very little natural gas has been found below 20,000’ (except in these “cool” basins) because the overburden of the Earth crushed the porosity so that there is no place for the gas to reside.

[rellimpank]

--thanks--having been a hardrock miner most of my life, I'm more interested in what are the ultimate sources of geologic wonders such as the porphyry copper deposits, the Homestake orebody, etc.,--

--my point was that we really have little detail knowledge of events and processes that deep except that they occur in high temperature, high pressure environments-