This is answered if you’d like, by the fact that oil IS in fact pretty unique to where it’s coming from due to the variables in what creates it and the reservoir itself. Oil refineries themselves aren’t all uniform, they are unique to their feedstock, even if the principles are the same. Sour oil for instance, is crude oil with very high levels of sulfur, and a refinery that refines a more standard crude would face catastrophic difficulties in refining it. Either way, the hydrocarbon is the only bit that matters, the other trace elements don’t occur in large quantities, and part of the refining process itself implies things like calcium are “processed” out and left for the “bottom of the barrel” which is fuel that giant ships run, and it’s most certainly got all sorts of random components in its general makeup.

This is answered by the fact that oil IS in fact pretty unique to where it’s coming from due to the variables in what creates it and the reservoir itself. Oil refineries themselves aren’t all uniform, they are unique to their feedstock, even if the principles are the same. Sour oil for instance, is crude oil with very high levels of sulfur, and a refinery that refines a more standard crude would face catastrophic difficulties in refining it.