Crude oil (which
is commonly known as petroleum) is a naturally occurring liquid, non-renewable
source of energy found within the earth’s crust comprising of hydrocarbons (usually
the primary component), organic compounds (like nitrogen, oxygen and sulphur
that make up between 6%-10%) and small amounts of metal (like iron, vanadium,
copper and nickel that account for less than 1% of the total composition). Crude
oil even after the appearance of other forms of energy such as water, wind and
solar power has remained the main source of energy all over the globe. This
essays aims to give clear, detailed and specific information on the formation
of crude oil, its refining; components, properties, uses of crude oil and its
effects on the environment. By the end of this essay you will vividly
comprehend why crude oil is important not only to the other energy sector but
also to our lives in general. It is a backbone to most countries such as Libya,
Venezuela and Saudi Arabia.
Formation of Crude oil
oil extracted over the past century was formed millions of years ago, over 500
million years and some of the newest deposits formed over 50 million years ago.
Small marine animals and plants died millions of years ago and sunk to the
ocean floor or seabed where they decomposed and got buried under layers of sand
lack of oxygen on the sea bed, the bacteria could not decompose the remains
completely. The partially decomposed remains, overtime formed into a large mass
with the weight of sand and silt that was building up pressing down on them
causing them to be compressed into a thinner layer.
immense pressure created by heavy layers of sediments and natural heat from the
earth changed the chemical composition of the remains through a process called
diagenesis into a waxy compound called kerogen and then, with increased heat
into a liquid through a process called catagenesis. The oil is forced out from
its original area of formation and travels upwards through the cracks and gaps
in the shale formation until it reaches a new impermeable rock formation called
reservoir rock. The oil lays trapped here until it is discovered and extracted.
refining process depends on the chemical processes of distillation (separating
liquids by their different boiling points) and catalysis (which speeds up
reaction rates), and uses the principles of chemical equilibria. Chemical
equilibrium exists when the reactants in a reaction are producing products
which are recombined again into reactants. By altering the reaction conditions,
the amount of either products or reactants can be increased.
is carried out in three main steps.
Step 1 –
Separation The oil is separated into its constituents by distillation, and some
of these components (such as the refinery gas) are further separated with
chemical reactions and by using solvents which dissolve one component of a
mixture significantly better than another.
Step 2 – Conversion The various hydrocarbons
produced are then chemically altered to make them more suitable for their
intended purpose. For example, naphthas are “reformed” from paraffins
and naphthenes into aromatics. These reactions often use catalysis, and so
sulfur is removed from the hydrocarbons before they are reacted, as it would
‘poison’ the catalysts used. The chemical equilibria are also manipulated to
ensure a maximum yield of the desired product.
Purification The hydrogen sulfide gas which was extracted from the refinery gas
in Step 1 is converted to sulfur, which is sold in liquid form to fertiliser
manufacturers. The plant at Marsden Point also manufactures its own hydrogen
and purifies its own effluent water. This water purification, along with gas
‘scrubbing’ to remove undesirable compounds from the gases to be discharged
into the atmosphere, ensures that the refinery has minimal environmental