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UNIT 1
THE HISTORY OF PETROLEUM INDUSTRY

Petroleum is a mixture of naturally occurring hydrocarbons
that may exist in the solid, liquid or gaseous states, depending
upon the conditions of pressure and temperature to which it is
subjected. Virtually all petroleum is produced from the reservoir in
either liquid or gaseous form, and commonly, these materials are
referred to as either crude oil or natural gas, depending upon the
state of the hydrocarbon mixture. Petroleum consists of
approximately 11-13 wt % hydrogen and 84-87 wt % of carbon.
Traces of oxygen, sulphur, nitrogen and helium may be found as
impurities in crude oil. Crude oils obtained from different oil
reservoirs have widely different characteristics. Some are black,
heavy, and thick like tar, and others are brown or nearly clear with
low viscosity and low specific gravity.

Crude oil and Natural gas
Crude oil is a mixture of hydrocarbons that exists as a
liquid in natural underground reservoirs and remains a liquid when
brought to the surface. Petroleum products are produced from the
processing of crude oil and other liquids at petroleum refineries,
from the extraction of liquid hydrocarbons at natural gas
processing plants, and from the production of finished petroleum
products at blending facilities. Petroleum is a broad category that
includes both crude oil and petroleum products. The
terms oil and petroleum are sometimes used interchangeably.
Crude oil and natural gas are nonrenewable sources of
energy (fossil fuels). Crude oil is a mixture of various hydrocarbon
compounds and other materials; usually containing about 84%
carbon; 14% hydrogen; 1 to 3% sulfur; and nitrogen, oxygen,
heavy metals, and salts that total less than 1%. Crude oil can range
from light, volatile oils that are highly fluid to nonfluid oils (e.g.,
residual oils, heavy crude oils, and some high paraffin oils). When
it is brought to the surface, crude oil may also contain natural gas
and product fluids such as salt water (i.e., produced water) and
both dissolved and suspended solids. The natural gas is either

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