Ranking the world's top oil companies

Petroleum Intelligence Weekly's annual ranking of the world's top oil companies - based on criteria like reserves, refining capacity, and sales - was just released, and there is just a bit of shuffling near the top. Four of the five top oil companies now are state owned - Saudi Aramco, Iran's NIOC, Venezuela's PDV, and China's CNPC. A few highlights:

• Saudi Aramco remains No. 1, and China's CNPC surpasses BP and Shell.

• Russia's Rosneft makes biggest jump, from 24th to 16^th.

• Majority state-owned national oil companies now make up 27 of 50.