Oil is an organic matter formed millions of years ago. Its origin is from plants and marine animals that were buried by sedimentary rocks (porous rocks formed by limestone and sand).

With the action of heat, pressure, microorganisms and time, this organic matter turned into petroleum.

The word oil comes from Latin petrawhich means stone and oleum, which means oil. Oil is a dense, oily liquid of generally dark color.


It can be found on the sea floor, but is also found on dry land. It is more common to find oil over salt water, so its marine origin, and under a layer with gases such as methane (CH4), ethane (C2H6), and others, at high pressures.

The discovery of oil wells are done in many ways. The most common is done by detonating explosive charges on the ground and measuring shock waves reflected in the various underground layers. From the study of these waves, it is possible to indicate the likely location of oil.

After finding oil, you need to do the extraction. It is made through the oil rigs. Extracting oil from the sea is one of the most difficult tasks.

Offshore Oil Rig

See the scheme of oil extraction:

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Oil extracted from the wells is pumped to the nearest deposits. It rests to decant salt water, clay and some existing impurities.

One of the worst oil impurities is sulfur (S). It is then pumped into storage tanks and sent by pipelines, which are special oil pipelines, to the refinery.

The refinery is where the purification and separation of oil components takes place. It is transformed into a series of derivatives by various methods.


One of the processes performed is fractional distillation. It is performed on large distillation columns. Each fraction of the oil has a mixture of several molecules that, depending on their size, occupy the distillation column. The lightest fractions are at the top of the tower, such as methane and ethane gases.

Here's how to distribute the oil fractions in a distillation column:


EW (° C)


1 to 4 C - Petroleum Gas

less than 20

Cooking gas

5 to 6 C - Ether

20 to 60

Paint solvent

6 to 7 C - Naphtha

20 to 100

Synthetic fiber fabric

5 to 10 C - Gasoline

40 to 200

Engine fuel

11 to 18 C - Kerosene

175 to 275

Aircraft fuel

15 to 18 C - Diesel Oil

275 to 400

Tractor Fuel, Train, Bus, Truck, Diesel

Above 17 C - Grease and Lubricating Oil

over 350

Parts & Machine Lubricant

Above 30 C - Asphalt (tar)

over 400

Paving of streets, roads, paraffins and Vaseline