The largest oil field in the world

The Ghawar field in Saudi Arabia is the largest oil field in the world.
It was discovered in 1937 and is located about 100 kilometers from the city of Dhahran, in the Eastern Province of that country. It occupies an area of ​​8,400 square kilometers (280
kilometers long by 30 wide).
Currently, this field is capable of producing between 4.5 and 5 million barrels of oil per day, which represents 6% of world production and 65% of Saudi production. It also produces about 2,000 million cubic feet of natural gas per day.
Since its production began in 1951 about 60,000 million barrels have been extracted. According to Saudi oil company Aramco, owner of Ghawar, it is still the largest oil field in the world. Although its production level is reduced by 2% and 8% each year, there are still some recoverable reserves of just over 70,000 million barrels.
Geology
The Ghawar oil field is made up of an anticlinal structure (convex fold) that is expressed on the surface by outcrop of tertiary rocks (relatively more modern). To the north, this structure comprises two anticlines (convex folds) parallel with a small depression between them.
The Ghawar anticline is supported on a horst (raised block) of the crystalline basement that initially ascended during the Carboniferous period (300 million years ago) and was reactivated, episodically, especially during the Late Cretaceous (100 million years). The Paleozoic section (ancient, at the base) was significantly eroded by the Hercynian discordance (ie the erosion that occurred about 280 to 250 million years ago).
The structure is asymmetrical, steeper to the west and becomes more complex in depth, where several horst (raised blocks) are found in the form of a staircase.
The main reservoir of Ghawar are the Jurassic limestones (160-180 million years) that are somewhat less than 100 meters thick and are 2,000-2,300 meters below the surface.
The deposition of calcareous rocks included grainy (marine) reefs in the north, improving the quality of the reservoir, which also improves upwards as it evolves from a relatively massive calcareous siltstone to a granular oolitic oolitic limestone (the oolites are micro-concretions spherical). Fracture density increases with depth increasing the permeability of fine-grained siltstones.
To be continued