An oil atlas
Proven reserves
Petroleum, whose name comes from the Latin “petra,” or rock, and “oleum,” or oil, seeps naturally to the Earth’s surface along fault lines and cracks in rocks, where it pools. How oil forms and where it is found:
World total 1.3 trillion barrels
267
178
Saudi Can. Arabia
Main oil and gas fields As of 2007 Oil Gas
Top countries, in billions of barrels, 2009
What are proven reserves?
136
Estimated amounts of crude oil that can reasonably be recovered from known reservoirs
Iran
115
104
99
98
60
44
36
Western Europe
Charts show percent of world total by region
21
16
15
13
12
11
7
9
6
Kuwait U.A.E. Libya U.S. Qatar Algeria Angola India Iraq Venezuela Russia Nigeria China Brazil Mexico Norway
3 U.K.
Eurasia
1%
7%
North America
16% Much of N.A.
reserves are located in oil sands in Alberta, Canada
Origins of fossil fuels Most geologists believe oil and natural gas derive from the fossils of microscopic animals and plants, such as algae and plankton, that lived in lakes and seas millions of years ago 1
Tiny marine life died and fell to the sea and lake floors; over time, it was covered with layers of sand and mud, forming a sedimentary basin
2
Over millions of years, accumulated layers of sediment covered the decaying matter, burying it deeper and deeper
3
Higher pressure and temperature nearer the Earth’s center transformed organic matter into hydrocarbons, long chains of carbon and hydrogen atoms
4
Temperatures of 140 F to 212 F (60 C to 100 C) led to formation of crude oil, which contains larger hydrocarbons, such as hexane and octane • Temperatures above 302 F (150 C) helped transform oil into natural gas, which has smaller hydrocarbon molecules, such as methane, propane and butane
A rock, a reservoir and a seal
Almost one-fifth of U.S. reserves – about 4 billion barrels – found in offshore fields in the Gulf of Mexico, most of that in deep water
Pacific Ocean Asia
2.5% Middle East
Atlantic Ocean
56%
Latin America
9%
Africa
8.5% Indian Ocean
Water surface
Anatomy of deep-water reservoirs: The Gulf of Mexico Since rivers can carry large amounts of sediment offshore, many sedimentary basins formed near river deltas, such as the Mississippi Delta Ocean floor
Underwater reservoirs Some of these reservoirs are located thousands of feet below the ocean floor
Where river sediments and coastal waters meet, the river slows down and sediment drops to the ocean floor; lighter particles can drift long distances before settling
Reservoirs
Sandstone
Salt
Oil and gas are found in sedimentary rock; as they form, they rise through layers of porous rock; much of the world’s oil and gas disappears naturally through this process
If sedimentary particles mix with organic debris, the process of forming hydrocarbons starts in the Gulf of Mexico, some of the oil and gas that formed is trapped by salt, rock-like crystalline structures, forming oil/gas reservoirs
© 2010 MCT Graphic: Pat Carr, Lee Hulteng
Land
Ocean
Sometimes, oil and gas migration is blocked by a layer of impermeable rock, which acts like a seal
Trapped oil
Hydrocarbons become trapped and accumulate in porous rock below, forming a hydrocarbon reservoir Reservoirs, once discovered, can be turned into oil and gas fields Source: U.S. Energy Information Administration, Energy Training Resources, International Association of Oil and Gas Producers, Americian Petroleum Institute, Jackson School of Geosciences at University of Texas
Abyssal plains Can be flat or mountainous, with deep canyons and valleys; oil reservoirs found below this floor
Continental drop Steep drop ending in abyssal plains, 1.8-3 miles (3-5 km) below sea level
Continental shelf Beach extends from shore into ocean
