Ghawar Field
Oil field in Saudi Arabia
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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 the context of issuing a bond to international markets. The bond prospectus revealed that Ghawar is able to pump a maximum of 3.8 million barrels (600,000 m3) per day—well below the more than 5 million barrels (790,000 m3) per day that had become conventional wisdom in the market.
Geology
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 (85 m) thick and occurs 6,000 to 7,000 feet (1,800 to 2,100 m) 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.
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History
In the early 1940s, Max Steineke, Thomas Barger and Ernie Berg noted a bend in the Wadi Al-Sahbah dry riverbed. 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.
Extraction of crude oil
Approximately 60–65% of all Saudi oil produced between 1948 and 2000, came from Ghawar. Cumulative extraction of petroleum through early 2010, has exceeded 65 billion barrels (1.03×1010 m3). In 2009, it was estimated that Ghawar produced about 5 million barrels (790,000 m3) of oil a day (6.25% of global production), a figure which was later shown to be substantially overestimated.
As of 31 December 2018, total reserves of 58.32 billion barrels (9.272×109 m3) of oil equivalent including 48.25 billion barrels (7.671×109 m3) barrels of liquid reserves have been confirmed by Saudi Aramco. Average daily extraction was 3.8 million barrels (600,000 m3) per day.
Ghawar also produces approximately 2 billion cubic feet (57,000,000 m3) of natural gas per day.
The operators stimulate production by waterflooding, using seawater at a rate said to be around 7 million barrels (1,100,000 m3) 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%.
Energy content
Taking the 1.9×108 tonnes (1.9×108 long tons; 2.1×108 short tons) production figure per year and the conventional energy density of crude oil (per the definition of the ton of oil equivalent) of 41.868 MJ/kg (5275.3 Wh/lb)) the total thermal energy equivalent produced yearly by the oil field is roughly 7.955 EJ or 2.21 PWh of thermal energy equivalent.
For comparison,
- North Antelope Rochelle Mine, the largest coal mine in the world, produced 85.3 Mt of coal in 2019 (down from over 100 Mt in 2015) at 1.746 EJ or 485 TWh of thermal energy equivalent.
- McArthur River uranium mine, the largest uranium mine in the world, produced 7.3 Mt (16.1 Mio lb) of yellowcake in fiscal 2017, equivalent to roughly 6.2 kt of uranium metal or 4.46 EJ (1240 TWh) of thermal energy at a burnup of 200 MWh/kg achievable in CANDU-type reactors, but much less in more widespread reactor designs.
- The largest solar farm in the world, Bhadla solar park in India, covering 57 km2 and boasting a nameplate capacity of 2255 MW would produce 17.778 PJ or 4938 GWh of electricity per year.
- The largest wind farm as of 2021, Gansu Wind Farm in China has a nameplate capacity approaching 8 GW with plans to ramp up to 20 GW. A 20 GW power plant at 100 % capacity factor could deliver 630.7 petajoules (1.752×1011 kWh) of electric output per year. However, once again due to the weather-dependency and intermittency of wind power, capacity factors for onshore wind installations like Gansu are typically much lower, ranging at 15-35% depending on local factors. 250000 standard tons of coal will be replaced per year at full deployment, which is equivalent to 7327 TJ (2035 GWh).
The Ghawar oil field is thus the largest single supplier of primary energy on Earth.
Reserves
In April 2010, Saad al-Tureiki, Vice-President for Operations at Aramco, stated, in a news conference reported in Saudi media, that over 65 billion barrels (10.3 km3) have been produced from the field since 1951. Tureiki further stated that the total reserves of the field had originally exceeded 100 billion barrels (16 km3).
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 170 billion barrels (27 km3) of original oil in place (OOIP), with about 60 billion barrels (9.5 km3) recoverable (1975 Aramco estimate quoted by Matt Simmons). The second figure, at least, was understated since that production figure has already been exceeded.