For the 20th year in a row, Saudi Aramco has been named the No. 1 oil company in the world by Petroleum Intelligence Weekly (PIW). The rankings are based on six operational criteria — oil reserves and production, natural gas reserves and output, refinery capacity and product sales volumes, according to a press release issued by Saudi Aramco yesterday. The omission of financial criteria allows the more equitable comparison of private sector and state-owned oil companies. Saudi Aramco has held on to the top spot amid general strengthening of national oil companies (NOCs) that has seen China's CNPC surpass BP and Shell. Russia's Rosneft made the biggest jump, from 24th to 16th on the table. In addition, three new, majority state-owned companies have appeared in the top 50 — Uzbekistan's Uzbekneftegas, China's CNOOC and Kazmunaigas of Kazakhstan. That brings the total number of NOCs in the top 50 to 27. --MORE