or oils? According to the basic definition, an oil is an organic
compound that is insoluble or not readily soluble in water.
It could be a petroleum-based product as well as a non-petroleum
product both categories comprise a number of different
kinds of oils.
"Oil" or "oils" are concepts that do not
necessarily refer to petroleum. Oil products used for energy
or transportation or as raw material for plastics are mineral
oils (petroleum-based oils) produced from crude oil. There
are, however, also a great variety of other naturally occurring
types of non-petroleum-based oil lipids,
oils, and wood-derived oils.
OILS MINERAL OILS
means "rock oil", from the Greek petros/Latin
petra (rock), and the Greek elaion/Latin
oleum (oil). The term petroleum is nowadays used as
a common denotation for crude oil (mineral oil) and natural
gas, i.e., the hydrocarbons from which various oil and
gas products are made. Petroleum, then, is a collective term
for hydrocarbons, whether solid, liquid or gaseous.
of natural gas and crude oil have formed over millions of
years as plants and animals have been broken down and undergone
chemical change at high temperature and pressure. One finds
petroleum in porous rock-forming large sedimentary basins,
where the oil and gas has been trapped by some kind of barrier
thereby forming a reservoir.
pumped out of a well on land or in the seabed, crude oil
is a complex mixture of thousands of different chemical components,
mainly organic compounds hydrocarbons
which usually make up about 95 per cent of the crude oil (however,
hydrocarbon contents as low as around 50 per cent also occur).
These hydrocarbons vary in toxicity and degradability, and
range from very volatile, light materials like propane and
benzene, to heavy compounds such as bitumens, asphaltenes,
resins and waxes. The remaining about five per cent of the
crude oil are made up of small amounts of oxygen, nitrogen
and sulphur, and traces of some fifty other elements, mainly
metals. Low-sulphur oil is in particularly high demand, since
it does not need to be desulphurized prior to use for heating
or as fuel.
composition of the crude oil depends on the "raw material"
from which the crude was originally formed, and on the conditions
that prevailed during its formation and thereafter. Physical
properties and chemical composition vary from one reserve
to another and even between different depths in the same well.
Thus, every crude oil is unique. Also, crude oils are often
characterized by the petroleum industry according to their
being used as fuel (for energy generation, machinery and vehicles),
or as a raw material in the petrochemical industry, crude
oil is refined into different fractions.
At the refinery, crude oil is separated into light and heavy
fractions, which are then converted into various products,
such as petrol, diesel oil, jet fuel, etc.
BASED OILS LIPIDS, ESSENTIAL OILS, WOOD-DERIVED OILS
which contain fatty acids, may be of animal origin
such as, e.g., whale, seal and fish liver oil, lard and milk
fat or of vegetable original, for example palm oil,
rapeseed oil, linseed oil, sunflower oil, olive oil and coconut
oil. Essential (ethereal) and wood-derived oils are usually
natural, including e.g. wood-derivated oils like resin/rosin
oils, as well as oils from flowers or fruits, such as essence
of roses, oil of lavender, jasmine, violet, orange, etc. They
can also be manufactured synthetically for use in paints (e.g.,
silicone fluids, and tung oils), or in foods and perfumes.
CRUDE OIL TO VARIOUS OIL PRODUCTS
The crude mineral oil pumped from wells is a mixture of natural
gas, water (formation water or production water) and hydrocarbons.
First, the gas is separated from the oil and water and further
treated. Water and solid particles are removed from the oil
component of the crude, which is transported to a refinery
for distillation and other separation and refinement processes
. The resulting products from these processes are a number
of fractions with different characteristics and ranges
gasoline (benzine and naphta), the end product of which
is petrol (gasoline);
distillates, the end products of which include light gas
(fuel) oil, diesel oil, aviation fuels, kerosene, etc.;
distillates, giving end products like heavy gas (fuel) oil
for cracking processes, as well as lubricants, waxes, etc.;
the end products of which are heavy fuel oils, asphalt (bithumen),
tar and coke.
physical and chemical properties of oils that will affect
the behaviour and effects
of oil in water and aquatic environments are its surface tension,
specific gravity, and viscosity. The composition and characteristics
of an oil, together with a number of circumstances relating
to the time and place of the spill, the amounts of oil, weather
conditions etc. will determine how persistent the oil will
be, how it will spread, whether it will evaporate or sink,
etc. From an oil spill response point of view, crude oils
can be classified on a scale from light, volatile oils, over
non-sticky oils to heavy, sticky oils and non-fluid oils (see
EPA). Similarly, refined products can be
classified from lightweight gasoline and kerosene over lightweight
and medium-weight fuel oils to medium-weight and heavyweight
fuel oils/bunker oils (see EPA).