Not all oil fields are created equal. It’s my ‘layperson’ understanding that some are not even really oil in the beginning of the 20th century sense.
1. Some only produce ‘light’ products of the kind one gets from the top half of a conventional oil distillation column. Some produce gas and liquids that have to be ‘reformed’ into heavier products (expensive).
https://mastodon.social/@urlyman/111126609525069718
2. And some come from fields with productivity that declines really sharply…