Current world-wide oil production is c. 83 million barrels per day [1]. With the estimated 511 billion barrels, about 2x of Saudi Arabia’s reserves (2005, [2]), that would last for about 15 years.

[1] https://ycharts.com/indicators/world_crude_oil_production

[2] https://www.nationmaster.com/country-info/stats/Energy/Oil/R...