Petroleum has a biological basis which would tend to rule that out.
That may be so, but how do we really know they are making the right connections, case in point, they have been looking for the missing link in man for years and have not found it, and the reason they are looking for it is not because evidence points to it but because they have predetermined that Adam came from a long line of ancestors, the reason they have not found it is because it is not there.
So in this case its just the opposite, they are not looking for anything else.