Coal petroleum class 8

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How is petroleum formed?

Petroleum (also known as crude oil) is a fossil fuel that was formed from the remains of ancient marine organisms.
Millions of years ago, algae and plants lived in shallow seas. After dying and sinking to the sea, the organic material got mixed with other sediments and was buried. Over millions of years under high pressure and high
temperature, the remains of these organisms transformed into fossil fuels. Coal, natural gas, and petroleum are
all fossil fuels that are formed under similar conditions. Today, petroleum is found in vast underground reservoirs where ancient seas were located. Petroleum reservoirs can be found beneath land or the ocean floor. The
crude oil is extracted with giant drilling machines. Crude oil is usually black or dark brown, but can also be yellowish, reddish, tan, or even greenish. Variations in colour indicate the distinct chemical compositions of different supplies of crude oil. Petroleum is used to make gasoline, an important product in our daily lives.

Petroleum reservoirs
Petroleum is found in underground pockets called reservoirs. Deep beneath the earth,  the pressure is extremely high. Petroleum slowly seeps out towards the surface, where there is low pressure. The petroleum then collects
in reservoirs, which can be several hundred metres below the surface of the earth.

Petroleum Refining
The process of separating the various constituents of useful fractions of petroleum is known as the refining of petroleum. This process of refining is based on the difference in the boiling points of its constituents. This is an also called fractional distillation.

Natural Gas
“Fossil gas” often called “natural gas” or simply “gas” is found in natural gas fields and also in association with oil fields and coal beds. “Biogas” is created by methanogenic microbes in marshes, landfills, sewage, and sediments on the seafloor.
Before natural gas can be used as a fuel, it undergoes extensive processing to remove almost all materials other than methane. One of these materials is the valuable nonrenewable gas i.e. helium. After it is cleaned of its impurities, fossil gas becomes a clean-burning and efficient source of heat used in a wide array of applications, including generation of electricity in central power plants, factories and home. The clean natural gas also becomes a valuable source of methane building blocks (CH4) that can be readily converted to ammonia (NH3) for making
fertilizer or methanol (CH3OH) for making industrial chemicals. Natural gas in the form of Compressed
Natural Gas (CNG) or Liquefied Natural gas (LNG) is used as a fuel for vehicles in some countries like Argentina, Brazil, Pakistan, Italy and India.


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