Function of the Earth's oil deposits?

The carbon abundance of the Earth's crust is mostly locked up in calcite and those deposits hold 10 times more carbon than all the organic carbon sources. The generation of hydrocarbons is not limited to living processes. They can be generated from calcite reactions too. So, Gold was at least partly right. The location of hydrocarbons deep in the crust is a question too.

Interesting. This brings up the big political question of whether this oil is extractable. (Of course, I don't think we should be burning more fossil fuels, but the oil-igarchy certainly does).

I've heard that oil fields are capped and closed before they are completely drained, because a point is reached where it takes more energy to pump the remaining oil out than the energy obtained from that oil. If this is the case, what "good" is the oil that is even further down and that would take even more energy to extract?

Emanuel

Political and ecconomic issues are subjects for other web sites. The science issues are all that matter here.