21. Sudan
Proven reserve: 6,800,000,000 billion barrels
Proven reserve: 6,800,000,000 billion barrels
In 2010, Sudan was considered the 17th-fastest-growing economy in the world and the rapid development of the country largely from oil profits.
However, because of the secession of South Sudan, which contained over 80 per cent of Sudan's oilfields, the country's economic forecast is uncertain.
22. Norway
Proven reserve: 6,680,000,000 billion barrels
Proven reserve: 6,680,000,000 billion barrels
On a per-capita basis, it is the world's largest producer of oil and natural gas outside the West Asia.
The petroleum industry accounts for around a quarter of the country's gross domestic product.