Here’s a reality check from The Economist:

WHEN activists, journalists and others speak of “Big Oil”, you know exactly what they mean: companies such as Exxon Mobil, Chevron, BP and Royal Dutch Shell. …

Yet Big Oil is pretty small next to the industry’s true giants: the national oil companies (NOCs) owned or controlled by the governments of oil-rich countries, which manage over 90% of the world’s oil, depending on how you count. Of the 20 biggest oil firms, in terms of reserves of oil and gas, 16 are NOCs. Saudi Aramco, the biggest, has more than ten times the reserves that Exxon does. …

But if the amount of oil at state oil companies’ disposal is not much of a worry, the way they manage it certainly is. Few of the princes, politicians and strongmen who wield ultimate authority over these firms can resist the urge to meddle. At best, that leads to the sort of inefficiencies found at most state-owned firms: overstaffing, underinvestment and so on. At worst, the business of pumping and selling oil is entirely subsumed by politics, as in the case of Petróleos de Venezuela, one of the biggest NOCs (see article). In either case, NOCs produce less oil, more expensively, than they should.