Where are the largest oil reserves?

   Canada has the world's largest oil reserves: 6 billion bar­rels of crude oil, mostly in Alberta, and more than 1 trillion barrels of oil in tar sands (sands soaked with an oil-producing substance) in northern Alberta. Production of oil from the sands began in 1967, but the process costs at least $11 per barrel (versus $2 per barrel for crude oil). Saudi Arabia has reserves of 263 billion barrels of crude oil; Iraq has 113 billion barrels.
   Currently only about one-third of the oil in most deposits is recoverable. Improved extraction methods—rather than new discoveries—most likely will increase the amount of reserves. Large oil deposits are believed to exist in Antarctica's continental shelf, but twenty-four countries have agreed to limit the continent to scientific investigation; extraction of oil, natural gas, and other minerals is banned by treaty until 2041.