The process of drilling for oil produces the deepest holes in the Earth ever created. Oil must be pulled up from miles below the ground, where it's been forming through the long processes of time.
The rock brought up to the surface while drilling for oil can be millions of years old. The millions of years have formed a protect layer on top of whatever's down there, covering with layer after layer after layer of dirt and rock. What is it down there, deep in the past, at the bottom of the hole? Is it just rock and oil, or is there something else being brought up out of the core of the Earth?
As far as I know, the abandoned derreck is still there.