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Oil and gas

An oil port and refineryAn oil port and refinery Oil is used as a fuel in power stations, cars, ships and aircraft. It is also essential for many chemical industries. Natural gas is used for domestic heating and cooking, generating electricity and fuel for vehicles. Like coal, oil and gas are fossil fuels: they come from the remains of tiny plants and creatures that lived in the oceans millions of years ago. Their remains accumulated on the seabed and slowly turned into oil and gas. About one fifth of the world’s oil supply is still found under the sea. It is extracted using oil platforms.

Formation of oil

Oil and gas were formed in the seas millions of years ago. When the tiny plants and animals that lived in the sea died, they sank to the bottom (1) and were buried under layers of sand and silt. These were gradually compressed into layers of sedimentary rock (2). The heat action of bacteria changed the remains into crude oil, also known as petroleum, and natural gases.Formation of oil Formation of oil Pressures in the Earth forced the oil up through the sedimentary rock, which has tiny holes in it like a sponge. The oil rose until it came to a layer of hard rock. If the hard rock formed a dome over the soft rock, the oil became trapped under it (3). Geologists looking for oil study the local rock formations and make test drillings. If oil is found, wells are drilled into the ground. When the drill reaches oil, the pressure may be enough to send it gushing up to the surface (4). If not, it is pumped. The crude oil from the well is sent by pipeline or tanker to a refinery.

Oil platform, Gulf of MexicoOil platform, Gulf of Mexico

Oil platform

The second tallest freestanding structure in the world (after the Burj Khalifa tower in Dubai) is the Petronius oil platform in the Gulf of Mexico. Only 75 m (246 ft) of it shows above the sea surface, but it descends 610 m (2001 ft) to the ocean floor.

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