Ghawar is an oil field located in Al-Ahsa Governorate, Eastern Province, Saudi Arabia. Measuring 280 by 30 km (174 by 19 mi), it is by far the largest conventional oil field in the world, and accounts for roughly a third of the cumulative oil production of Saudi Arabia as of 2018.
Ghawar is entirely owned and operated by Saudi Aramco, the state run Saudi oil company.
Ghawar occupies an anticline above a basement fault block dating to Carboniferous time, about 320 million years ago; Cretaceous tectonic activity, as the northeast margin of Africa began to impinge on southwest Asia, enhanced the structure.
Reservoir rocks are Jurassic Arab-D limestones with exceptional porosity (as much as 35% of the rock in places), which is about 280 feet thick and occurs 6,000-7,000 feet beneath the surface.
As of 31 December 2018, a total of 58.32 billion reserves of oil equivalent including 48.25 billion barrels of liquid reserves have been confirmed by Saudi Aramco. Average daily production was 3,800,000 barrels per day.
According to en.wikipedia