Question 1 What is petroleum?

Question 2 Where does petroleum occur?

Question 3 Describe the process of formation of petroleum?

Question 4 Where does petroleum occur?

Question 5 Describe the process of formation of petroleum?

Question 6 How is petroleum extracted?

Question 7 What is drilling rig?


Petroleum is a dark coloured,thick crude oil found deep below the ground in certain areas.

The name petroleum means rock oil.It is called petroleum because it is found under the crust of earth trapped in rocks.

1)Petroleum is a complex mixture of compounds which are made up of only two two elements:carbon and hydrogen.

2)It is insoluble in water.

3)It is a natural resource obtained from deep oil wells which are dug in certain areas of the earth.

4)It is also a fossil fuel.It is also called as crude oil or mineral oil.

Formation of petroleum

It was formed by the decomposition of the remains of tiny plants and animals buried under the sea millions of year ago.It is believed that millions of years ago,the tiny plants and animals which lived in sea,died.Their dead bodies sank to the bottom of sea and were soon covered with mud and sand.Due to high pressure,heat,action of bacteria,and in the absence of air,the dead remains of tiny plants and animals were slowly converted into petroleum.The petroleum thus formed got trapped between two layers of impervious rocks,forming oil deposit.

Occurrence of petroleum

1)It occurs deep under the surface of earth between two layers of impervious rocks.

2)It is lighter than water,so it floats over water.

3)Petroleum oil deposits are usually found mixed with water,salt and earth particles.

4)It is found in only certain areas of the earth.Natural gas occurs above the petroleum oil trapped under the rocks.

Extraction of petroleum

It is extracted by drilling holes in the earth’s crust,where the presence of oil has been predicted by survey.

The oil wells are drilled by using drilling rigs.

When an oil well is drilled through the rocks,natural gas comes out first with a great pressure and for a time,the crude petroleum oil comes out by itself due to gas pressure.After the gas pressure has subsided,petroleum is pumped out of the oil well.Some wells dug into earth yield both petroleum and natural gas but some wells yield only natural gas but no oil.

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