
Ghawar Field

Ghawar (Arabic: الغوار) is an oil field located in Al-Ahsa Governorate, Eastern Province, Saudi Arabia. Measuring , 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. In April 2019, the company first published its profit figures since its nationalization nearly 40 years ago in context of issuing a bond to international markets. The bond prospectus revealed that Ghawar is able to pump a maximum of 3.8million barrels a day—well below the more than 5million that had become conventional wisdom in the market.
Geology.
Ghawar occupies an anticline above a basement fault block dating to Carboniferous time, about 320million 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. Source rock is the Jurassic Hanifa formation, a marine shelf deposit of mud and lime with as much as 5% organic material, it is estimated that 1% to 7% is considered good oil source rock. The seal is an evaporitic package of rocks including impermeable anhydrite.
History.
In the early 1940s, Max Steineke, Thomas Barger and Ernie Berg noted a bend in the Wadi Al-Sahbah dry river bed. Measurements confirmed that the area had undergone geologic uplift, an indication that an oil reservoir may be trapped underneath. Oil was indeed found, in what turned out to be the southern reaches of Ghawar.
Historically, Ghawar has been subdivided into five production areas, from north to south: 'Ain Dar and Shedgum, 'Uthmaniyah, Hawiyah and Haradh. The major oasis of Al-Ahsa and the city of Al-Hofuf are located on Ghawar's east flank, corresponding to the 'Uthmaniyah production area. Ghawar was discovered in 1948, and put on stream in 1951. Some sources claim that Ghawar peaked in 2005, though this is denied by the field operators.
Saudi Aramco reported in mid-2008, that Ghawar had produced 48% of its proven reserves.
Production.
Approximately 60–65% of all Saudi oil produced between 1948 and 2000, came from Ghawar. Cumulative production through early 2010, has exceeded . In 2009, it was estimated that Ghawar produced about of oil a day (6.25% of global production), a figure which was later shown to be substantially overestimated.
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.
Ghawar also produces approximately of natural gas per day.
The operators stimulate production by waterflooding, using seawater at a rate said to be around 7million gallons per day. Water flooding is said to have begun in 1965. The water cut was about 32% in 2003, and ranged from about 27% to 38% from 1993 to 2003. By 2006, North Uthmaniyah's water cut was about 46%.
Reserves.
In April 2010, Saad al-Tureiki, Vice-President for Operations at Aramco, stated, in a news conference reported in Saudi media, that over have been produced from the field since 1951. Tureiki further stated that the total reserves of the field had originally exceeded .
The International Energy Agency in its 2008 World Energy Outlook stated that the oil production from Ghawar reached 66 Bbo in 2007, and that the remaining reserves are 74 Bbo.
Matthew Simmons, in his 2005 book "Twilight in the Desert", suggested that production from the Ghawar field and Saudi Arabia may soon peak.
When appraised in the 1970s, the field was assessed to have of original oil in place (OOIP), with about recoverable (1975 Aramco estimate quoted by Matt Simmons). The second figure, at least, was understated, since that production figure has already been exceeded.