Reserve values are in billion barrel units.
Year 2016

Venezuela	300
Saudi Arabia	267
Canada	171
Iran	158
Iraq	143
Kuwait	102
United Arab Emirates	98
Russia	80
Libya	48
Nigeria	37
United States	35
Kazakhstan	30
Qatar	25
China	25
Brazil	16

The above chart is for proved oil reserves in the specified countries. A "proved" reserve is one which has at least a 90% probability of production, within the constraints of modern technologies, current costs of production, and political conditions.