Peak Oil Theory has been responsible for the squishiest of moving time targets. This gives great credence to the operation of other mechanisms for oil creation than biological fossils.
I thought I read years ago that supposedly “depleted” Oil Fields were refilling (for lack of a better word) and were being used again.
Of course, Fracking has been responsible for reaching Oil Reserves thought out of reach.
http://sciencemyths.blogspot.com/2008/07/myth-of-unlimited-abiotic-oil.html