State-owned energy giants and international majors continue to top lists of the world’s largest oil companies. But the U.S. shale revolution is beginning to make a mark, as U.S. independent oil and gas producers rise in the ranks.

Energy Intelligence has released its list of the world’s 100 largest oil and gas companies, with several independents — including  Houston-based Anadarko Petroleum and Apache Corp. — making among the biggest gains. The annual ranking is based on the prior year’s reserves, production, refined product sales and refinery distillation capacity.

Anadarko jumped two spots to No. 44 and Apache rose one spot to No. 41. Oklahoma City-based Chesapeake Energy broke into the top 50 for the first time, ranking No. 47, as it shifts its focus from natural gas to higher-value oil and liquids production. Devon Energy, also based in Oklahoma City, rose three places to No. 41.

Meanwhile, the nation’s largest independent oil and gas company ConocoPhillips took a dive, falling 19 spots to No. 31, following the spinoff of its refining arm, Phillips 66, last year.

See which companies hold the top 20 spots, and how their ranks have changed, in the slideshow above.

Sourced from Fuel Fix