As of 2011, the countries that produced the most oil were Saudi Arabia, Russia, and the US, followed by China and Iran. New access to oil previously locked in shale (i.e., rock) means that, according to the International Energy Agency (IEA), the US will likely surpass Russia in oil production by around 2015 and Saudi Arabia by around 2020. It's reported that US oil imports would likely drop so much, as a result, that the US could actually become a net exporter of oil. Despite this, the change could be temporary — developments in shale gas extraction technologies in other countries as well as the recovery of Iraq's oil industry could change the rankings again.
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