The vast petroleum and hydrocarbon reserves trapped beneath the desert sands and offshore fields of Saudi Arabia originated from organic matter deposited in ancient shallow seas millions of years ago, predominantly during the Jurassic and Cretaceous periods. Geological formations hosting these massive oil deposits range from approximately 100 million to over 150 million years in age. Tectonic movements, intense subterranean heat, and impermeable caprock layers over immense geological timeframes preserved these rich organic deposits, creating the world's most prolific petroleum reservoirs.