“...how can it come from the depths of the earth?”
Read up on the abiotic theory of oil. It’s far more persuasive than the dino theory.
No serious scientist claims that oil comes from dinosaurs. That was something erroneous put into children’s textbooks years ago. Kind of like how eating carrots makes your eyesight better, until someone went back and checked the math and found that they have missed several decimal places. The science of petroleum, as algore would say, is settled. Google kerogen. Tasmanites.