What is the purpose of oil?

[Theory5]

Oil. It heats our houses, it powers our cars, and to make that happen we pump billions and billions of gallons out of under the oceans and the deserts and the tundra. But is it important to the environment? Do all those gallons of oil do anything under all that rock and water?

[Moontanman]

Oil. It heats our houses, it powers our cars, and to make that happen we pump billions and billions of gallons out of under the oceans and the deserts and the tundra. But is it important to the environment? Do all those gallons of oil do anything under all that rock and water?

 

Yes they are a food source for "The Deep Hot Biosphere" (Thomas Gold)

[CraigD]

Do all those gallons of oil do anything under all that rock and water?

They occupy volume in the stony/sandy formations that hold them, so, in principle, if you “sucked a well dry”, you might cause some settling of the oil-bearing formation and the earth over it, along with some accompanying small temblor activity. However, since it’s more difficult to pump more than the fraction of the oil available via natural pressure oil reservoirs, especially large ones, are usually refilled, typically with water, or less commonly, gas. So most oil well are little if any less full when they’re retired than they were before pumping started – just full of something different.

 

It’s important to visualize that, even though graphics of them often depict them as vast, hollow, cavernous spaces, oil reservoirs are in actuality filled with porous rock and sand. Though, as Moontanman notes, there’s reasonable scientific speculation that some complex biology occurs in oil reservoirs and other underground formations, I don’t think the partial extraction (even as oil grows more and more scarce, it will likely never be profitable, or even technically possible, to extract all of the oil from a reservoirs) and replacement that we humans do will have a significant effect on any of that.

 

The major environmental impact of oil extraction is almost certainly due to spilling it in small and accidentally large amounts into surface ecosystems and human water supplies, and, or course, to releasing its visible and invisible combustion exhaust into the atmosphere. Any deep subsurface ecology affected by humans is, I strongly suspect, insignificant in comparison.