You mean like right now we just need enough oil fields to hollow out a quarter of Spain? Here's the numbers: Size of Ghawar oil field: 280 km × 30 km Fraction

You mean like right now we just need enough oil fields to hollow out a quarter of Spain? Here's the numbers: Size of Ghawar oil field: 280 km × 30 km Fraction of global oil produced by Ghawar: 6.25% Size of Spain: ca. 500,000 km^2 Do the math yourself.