The term ‘petroleum’ is derived from
the latin words ‘petra’ meaning rock and ‘oleum’ meaning oil. It is a fossil
fuel formed from the remains of ancient marine organisms through decaying
process. Petroleum is a complex mixture of hydrocarbons that occur in Earth in
liquid, gaseous, or solid form. The term petroleum commonly denotes the liquid
form, crude oil. But technically petroleum also includes natural gas and
bitumen, a solid form. The natural gas and the crude oil constitute the primary
People in ancient
cultures used crude oil for binding materials. It was also used as a sealant
for water proofing various surfaces.
1. Occurrence of
The chief petroleum producing
countries are U.S.A, Kuwait, Iraq, Iran, Russia and Mexico. In India, petroleum
is found in Assam, Gujarat, Maharashtra (Mumbai), Andhra Pradesh (Godavari and
Krishna basin) and Tamil Nadu (Cauveri Basins).
By drilling through the earth the
crude oil is pumped out from the well as a black liquid.
The first oil well in
the world was drilled in Pennsylvania, USA in 1859. The second oil well was
drilled in Makum, Assam, Indiain 1867.
2. Refining of crude
The crude petroleum obtained from
the well is a dark colored viscous liquid which contains many impurities such
as water, solid particles and gases like methane and ethane. To make it useful
for different purposes, it must be separated into various components. The
process of separating petroleum into useful by-products and removal of undesirable
impurities is called refining. The steps involved in this process are given
The crude oil obtained from the oil
wells will have salt water mixed with it. As the first step the water is removed
from the crude oil.
of sulphur compounds
The crude oil will have harmful
sulphur compounds as impurities. In this step these impurities are removed.
Petroleum is a mixture of various
constituents such as petroleum gas, petrol, diesel, kerosene, lubricating oil,
paraffin wax, etc. The process of separation of various constituents or
fractions of petroleum is done by fractional distillation in fractionating
columns. The process of heating a mixture of liquids having different boiling
points and then separating them by cooling is called fractional distillation.
Crude petroleum is first heated to
about 400°C in a furnace. As the vapours of crude oil move up the tower, the
various fractions condense according to their boiling point ranges. The various
fractions of petroleum obtained are given in Figure 15. 17. Many useful
substances are obtained from petroleum and natural gas. These are termed as
‘petrochemicals’. These are used in the manufacture of detergents, fibres, and
other man-made plastics like polythene. Hydrogen gas obtained from natural gas,
is used in the production of fertilizers. Due to its great commercial
importance, pertoleum is also called ‘black gold’.
3. Uses of Petroleum
Products obtained from crude oil
have a number of uses.
* Liquefied Petroleum Gas or LPG is
used in houses as well as in the industry.
* Diesel and petrol are used as
fuels for vehicles. It is also used to run electric generators.
* Petrol is used as a solvent for
* Kerosene is used as a fuel for
stoves and also in jet planes.
* Lubricating oil reduces wear and
tear and corrosion of machines.
* Paraffin wax is used to make
candles, ointments, ink, crayons, etc.
* Bitumen or asphalt is mainly used
to surface roads.
Find out where
petroleum is extracted on a large scale in India. Also list out the petroleum
refineries in India.