The Canadian & Venezuelan oil sands have about 4 trillion barrels of "Original Oil in Place". At current oil prices and level of technological development, only about 10% of this oil is considered recoverable and as such counted as reserves. But technology marches on, and if we start running out of oil from other sources, so will oil prices. So really, the world has hundreds of years worth of reserves.

Much more concerning is that we have to keep ~80% of those 52 years worth of oil in the ground to keep climate change under the 2 degree goal...