THE WORLD BIGGEST 10 OIL AND GAS COMPANIES...

1. Saudi Aramco - 12.5 million barrels per day

Saudi Aramco is by far the biggest energy company in the world, generating more than $1 billion a day in revenues. This image depicts the Shaybah mega-project, sitting on more than 15 billion barrels of oil in the Rub al-Khali desert. Aramco's biggest field, Ghawar, can do 5 million bpd. (Note: 2012 working interest production volumes calculated by Wood Mackenzie reflects oil plus the energy equivalent in natural gas.)

2. Gazprom - 9.7 million barrels per day

Russia's Gazprom is the world's largest producer of natural gas. Controlled by the Kremlin, Gazprom's monopoly on gas deliveries to much of Europe provides President Vladimir Putin a prime lever for projecting power in the region. Gazprom's profits are more than $40 billion a year. (Note: 2012 working interest production volumes calculated by Wood Mackenzie reflects oil plus the energy equivalent in natural gas.)

3. National Iranian Oil Co. - 6.4 million barrels per day

Iran has been forced to curtail oil production due to international sanctions, but remains a huge oil and gas producer. To skirt sanctions, Turkey and India have reportedly been paying for Iranian oil with gold. The Strait of Hormuz remains the world's most significant choke point for oil. Iran has threatened to close the Strait if attacked. (Note: 2012 working interest production volumes calculated by Wood Mackenzie reflects oil plus the energy equivalent in natural gas.)

4. ExxonMobil - 5.3 million barrels per day

Exxon's $40 billion in annual profits don't seem like a lot when you consider their $400 billion in sales. It takes giant projects to "move the needle" for the Big Unit. That means CEO Rex Tillerson has to make friends with potentates. In this picture from last April, Tillerson is meeting with Russia's Vladimir Putin to iron out a joint venture between Exxon and Russia's state-controlled oil giant Rosneft. (Note: 2012 working interest production volumes calculated by Wood Mackenzie reflects oil plus the energy equivalent in natural gas.)

5. PetroChina - 4.4 million barrels per day

The largest of China's three state-controlled oil giants, PetroChina also has the highest market cap of any of the publicly traded giants. The company already produces more oil than ExxonMobil, and considering the estimates of massive shale gas under China, could someday vie with Gazprom as a regional gas power. (Note: 2012 working interest production volumes calculated by Wood Mackenzie reflects oil plus the energy equivalent in natural gas.)

6. BP - 4.1 million barrels per day

Bob Dudley is seeking to turn the giant formerly known as British Petroleum around. Selling assets, settling lawsuits, promising improvements. BP may not maintain its 4.1 million barrels per day for long; it is in talks to sell its 50% stake in Russian venture TNK-BP, which provides a quarter of production. (Note: 2012 working interest production volumes calculated by Wood Mackenzie reflects oil plus the energy equivalent in natural gas.)

7. Royal Dutch Shell - 3.9 million barrels per day

Shell is hoping this summer to start drilling for oil in Alaska's Chuckchi Sea. For years since leasing offshore blocks from the federal government Shell has been perfecting its drilling plan and preparing the Kullukfloating drilling rig, pictured here in the Puget Sound by Seattle. (Note: 2012 working interest production volumes calculated by Wood Mackenzie reflects oil plus the energy equivalent in natural gas.)

8. Pemex - 3.6 million barrels per day

Production from Mexico's biggest field, Cantarell (pictured) has plunged from 2 million bbl per day to roughly 600,000 now. State-owned Pemex is working to replace that shortfall with other fields. Mexico's incoming President Enrique Pena Nieto has said reforming Pemex to allow foreign investment will be his signature issue. (Note: 2012 working interest production volumes calculated by Wood Mackenzie reflects oil plus the energy equivalent in natural gas.)

9. Chevron - 3.5 million barrels per day

Chevron bought Atlas Petroleum in 2010 for $4.3 billion to gain acreage in the Marcellus and Utica shales. With gas prices low, some expect a bigger deal to come. (Note: 2012 working interest production volumes calculated by Wood Mackenzie reflects oil plus the energy equivalent in natural gas.)

10. Kuwait Petroleum Corp. - 3.2 million barrels per day

Kuwait's oil company was originally formed in 1934 by what are now Chevron and BP. In 1975 the company was nationalized. Kuwait's fields suffered greatly by fires set by Saddam Hussein's forces in 1990. Kurwait's biggest field, Burgan, continues to be operated by Chevron. (Note: 2012 working interest production volumes calculated by Wood Mackenzie reflects oil plus the energy equivalent in natural gas.)

Collection by M.Ajmal Khan.