http://www.wired.com/2014/01/an-artist-records-the-mysterious-rumblings-of-middle-earth/
This one is in Germany. But the Soviets attempted to dig the deepest hole ever. I think they reached nine miles. The amazing thing was how hot it was and the stunning amount of water they found.
There’s a theory, called “the hot biosphere” that all oil is produced very deep by bacteria and filters up. Wells that were pumped dry in the 40’s are producing again, which is unlikely if they were from ancient dinosaurs. Deep drilling in Sweden and off Viet Nam produced oil at depths where there were never any dinosaurs or ancient buried forests and bogs.
We know less about the inner Earth than about almost anything else. (And, darned little about the deep oceans.)
That’s not a theory, here in the world’s oil expert capital, we have known this for some time. There was no way there was that much “fossil” material below decks to do this.