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Petroleum

Petroleum

Petroleum is a fossil fuel. It is dark coloured viscous and foul smelling liquid commonly called crude oil.it is always found trapped between two impervious rocks. It is derived from Latin word petra means rocks and oleum means oil. Thus, petroleum laterally means rock oil.

Petroleum is a complex mixture of solid, liquid and gaseous hydrocarbons mixed with salt water and earthy particles.

Origin

Millions of years ago, a large number of plants and animals lived in the sea. They died and their bodies sank to the sea bed and got covered with sand and mud.in the absences of air under very high temperature and pressure of earth their bodies decayed and converted into petroleum. These  products got trapped into two layers of impervious rocks forming oil trap. The natural gas always collects above the petroleum under high pressure in a dome shaped rock called rock cap.

Occurrence

Petroleum occurs at  a moderate depth 500m. to 2000m. between two layers of  impervious rocks. The petroleum deposits usually found mixed with salt water. Being lighter than salt water petroleum floats over it. Wells are drilled to obtain petroleum. Natural gas comes out first and then  petroleum.

Refining

Petroleum is refined by crude oil by fractional distillation. Due to difference in temperature, the vapours with higher boiling point condense first, but the vapours with lower boiling point rise up and condense in different parts of fractionating column.

In the fractional distillation of petroleum, the residual oil liquifies at 400o C. fuel oil at 350 o C. to 400 o C., diesel oil at 250 o C to 350 o C., kerosene oil at 170 o C. - 250 o C. and gasoline at 40 o C- 170 o C.

 Petroleum gas does not condense and is taken out from the top of the fractionating column.

Natural gas

Natural gas was formed millions of years ago along with petroleum. Natural gas consists of 95% methane and 5% of a mixture of ethane and propane. The natural gas always collects above the petroleum under high pressure in a dome shaped rock called rock cap.

 

 

 

 

 

 

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