(Bloomberg) — Saudi Arabia’s oil fields, responsible for almost a 10th of global crude production, are in the firing line. Recently, they’ve been targeted by air, sea, and land.
Flaring tensions in the Gulf have seen some of the world’s biggest crude deposits, along with processing and transport infrastructure and vessels, targeted by explosives-laden drones and bombings.

The threats to the kingdom’s crude production and infrastructure shine a light on the risk to global oil supply given that state-owned Saudi Aramco is the world’s largest exporter. Saudi Arabia’s more than 100 crude deposits contain some 257 billion barrels of proved oil reserves, the world’s biggest conventional finds.

Saudi Arabian Oil Co., as Aramco is officially known, is able to pump as much as 12 million barrels a day. The company produced 10 million barrels daily during the first half of the year, keeping as a policy some 2 million barrels of capacity unused to allow it to react to any supply shortages. Aramco exports 7 million barrels of crude a day, more than any other company. This makes its role as a global swing producer and the security of its oil fields vital to global markets.

About three quarters of Aramco’s daily output come from four main fields: Ghawar, Khurais, Safaniyah and Shaybah. Those main deposits are in the eastern part of the country, either tucked between dunes and below vast expanses of desert or sitting underneath the waters of the Persian Gulf. Most of that crude passes through the Strait of Hormuz, the narrow shipping chokepoint leading out of the Gulf.

Below are descriptions of the main fields:

Ghawar

• Production capacity: 3.8 million barrels a day
• Crude grade produced: Arab Light
• The world’s largest conventional onshore field in terms of reserves and more than 200 kilometers (124 miles) long, according to Aramco
• Discovered in 1948 by an American geologist, Ghawar has produced more than half the crude that Aramco has pumped, according to an April bond prospectus
• The company’s disclosure of the maximum sustainable capacity of Ghawar in the April prospectus showed output was considerably lower than the 5 million barrels a day many market analysts assumed it was producing

Khurais

• Production capacity: 1.45 million barrels a day
• Crude grade produced: Arab Light
• Discovered in 1957, Aramco completed an expansion plan on the field last year to raise capacity from about 1.2 million barrels a day

Safaniyah

• Production capacity: 1.3 million barrels a day
• Crude grade produced: Arab Heavy
• Found in 1951 and lying mainly beneath Persian Gulf waters, Safaniyah is, according to Aramco, the world’s largest conventional offshore oilfield
• Safaniyah stretches into the Neutral Zone, an area shared by Saudi Arabia and Kuwait, with the portion of the field located there known as Khafji; Neutral Zone output of about 500,000 barrels a day has been halted for about four years

Shaybah

• Production capacity: 1 million barrels a day
• Crude grade produced: Arab Extra Light
• This is the field which was targeted most recently by Iran-backed Houthi militia from Yemen in an attack using bomb-laden drones
• One of Aramco’s most remote, the company constructed roads and an airstrip in the vast Rub Al-Khali desert, an area known as the Empty Quarter, in order to bring the equipment needed to build the facility across towering sand dunes
• Discovered in 1968, challenges, including the dunes standing more than 300 meters (984 feet) high and summer temperatures of almost 50 degrees Celsius (122 degrees Fahrenheit) delayed crude production until 1998; output later expanded
• The field holds about 14.3 billion barrels and is linked to the main export terminals by a 645-kilometer (401 miles) pipeline

Manifa

• Production capacity: 900,000 barrels a day
• Crude grade produced: Arab Heavy
• Aramco expanded the offshore field this decade, bringing new oil supplies to markets
• To develop Manifa, the company built an archipelago of causeways connecting man-made drilling islands to support equipment while allowing normal flows of currents and sea life

Zuluf

• Production capacity: 825,000 barrels a day
• Crude Grade Produced: Arab Medium

Other Deposits

• Aramco struck oil at the Dammam No. 7 well in 1938 when it was still a joint venture of American companies
• The Damman field, located underneath Aramco’s present headquarters campus, is still pumping and the company is currently expanding drilling and production at the deposit
• The Marjan and Berri fields are also undergoing expansion projects that will add 550,000 barrels a day of new capacity by 2023, Khalid Al-Dabbagh, senior vice president for finance, said on a conference call this month.

Western Fields

• Aramco is drilling for oil and natural gas at fields in the Red Sea
• The company is looking for gas at unconventional fields in the northwest of the kingdom to meet regional power demand
• Aramco serves most of its western refineries via the 5 million-barrel-a-day East-West pipeline, running from deposits in the Gulf area to Yanbu on the Red Sea; the company is expanding the link to be able to transport 7 million barrels a day by September