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The origins of the fuels that we take for granted today - and other modern products derived from oil (plastics, synthetic textiles, paint,
make-up ...) - go back several millions of years.
Now ...
... then ...
All living material is based on chains of carbon and hydrogen atoms.
Crude oil (the form in which oil is found when extracted) and natural gas
(the fuel that we use for cooking and heating) are also based on chains
of carbon and hydrogen atoms, in the form of chemical compounds known as
hydrocarbons. This is no coincidence!
The hydrocarbons in crude oil and natural gas are the product of the decay
of living organisms long, long ago.
In fact the formation of gas and oil began millions of years ago, when
the remains of microscopic plants and animals (known as phytoplankton and
zooplankton) settled on the sea bed. They were buried deeper by sediments
like clay and sand as the years went by. The sedimentary layers continued
to accumulate, and the increased pressure and temperature helped to turn
much of the organic matter into the hydrocarbons that make up oil and gas.
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| Anticline | Oil and gas in spaces within the rock (greatly magnified) |
The oil and gas formed in this way migrated upwards. Some of it reached the surface and escaped. However, under certain geological conditions, some was trapped underground - not as a 'lake', but in the pores of the rock itself. This is known as a reservoir.
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| Plankton magnified under microscope | A hydrocarbon molecule |
A typical formation in which oil or gas may be trapped is an anticline,
where the rocks have been buckled by movements in the Earth's crust into
a dome shape. If the dome has a cap of impermeable rock (rock which the
oil and gas cannot pass through) it will remain in this 'trap' until it
is drilled for and brought to the surface.
Natural gas or methane can also be found together with coal, as well
as oil. Coal is formed by the deep burial and decomposition of forests
of large ferny plants on land (rather than microscopic organisms in the
sea).
... and now
It is the places where such deposits of oil and gas are found that
have become centres for the oil and gas industry's exploration and production.
It is the story of this exploration, production, the industry's many other
activities and the profound effect that they have on all of our lives that
is told in these pages.
| Oil and natural gas (like coal) are fossil fuels. This means that they originated from tiny animals and plants that died millions of years ago. It also means that oil and gas are finite resources. In other words, they are limited and are not being replaced. |