Counterexample: China. Or plenty of African countries. Being a petrocracy certainly makes authoritarianism easier, but it's not at all a requirement.
It means a particular combination of autocracy and oil-dependence. It results in especially toxic regimes, that can be kept stable for quite a long time.
Counterexample: China. Or plenty of African countries. Being a petrocracy certainly makes authoritarianism easier, but it's not at all a requirement.