What is petroleum?
A Combustion File downloaded from the IFRF Online Combustion Handbook
ISSN 1607-9116
Combustion File No:
186
Version No:
1
Date:
28-04-2003
Author(s):
Phil Bowen
Source(s):
See Combustion File
Referee(s):
Peter Roberts
Sub-Editor
Peter Roberts
Status:
Published
Sponsor:
University of Wales – Cardiff
1. Introduction
The word petroleum literally means ‘rock oil’, as it is normally found underground in
porous rocks, usually accompanied by gas. It is often used synonymously for ‘Crude Oil’,
‘Crude Petroleum‘, or simply ‘Oil’.
Petroleum is a dark coloured liquid with the potential to release energy to generate heat
through combustion, and is the source of a wide range of industrial liquid fuels for
process heating and power generation – see CF62 for an introduction to petroleum as an
industrial fuel.
Though its composition varies with geological location, a general indication of the
chemical composition (by weight) of petroleum would be: C(84%); H(14%); S(1-3%);
N(<1%); O(<1%); metals and salts (<1%).
The value of petroleum is due to its ease of storage, transportation, utilisation, high
stored-energy density and relative ease of conversion to thermal energy. The primary
use of petroleum fuel is for transportation, with industrial process heating and power
applications also accounting for significant consumption.
2. Formation of Petroleum
The vast majority of our energy sources – including petroleum - are derived from the
Sun. Petroleum is the remains of earlier vegetation and animal life, deposited as timestored Fossil Fuels.
The age of the Earth is believed to be over 2000 million years, with the accumulation of
energy via the deposition of eventual fossil fuels believed to have commenced some 500
million years ago, during the last quarter of Earth’s lifetime.
The parent materials of petroleum are considered to be marine in origin, and the
transformation from marine deposits to liquid fuel are assumed to be partly chemical in
nature, and partly due to anaerobic bacteria.
Once formed, petroleum migrates through porous strata under the action of its own
surface-tension forces and gas pressures, until it is either lost to the atmosphere or
held by an impervious ‘cap rock’ layer acting as a seal (See Figure 1). Due to the
migration from source rock to reservoir rock, the geological history of a petroleum
deposit is often difficult to trace.
(a)
(b)
(c)
Figure 1: Formation of Petroleum
3. Man’s Utilisation of Petroleum
Man’s utilisation of petroleum fuel has been intermittent over the last 5000 years. What
could be called the first oil era, between 2500-1000 BC, took place during the
Babylonian Era, when use was made of oil seepages, or shallow deposits, as a fuel to fire
high temperature processes such as the manufacture of terra-cotta.
Subsequent generations established small industries for distillation of oil from shale,
tar-sand and coal, driven primarily by the need to find superior fuels to bio-oils and the
dissatisfaction with artificial illumination. However, it wasn’t until Edwin Drake of
Titusville (Pennsylvania) drilled a well specifically to locate oil in 1859, that the second –
current - oil era commenced in earnest. Drake discovered petroleum at 69 feet and
produced at the rate of 800 gallons per day.
Increased supply of oil through advanced exploration (See Figure 2) and production
techniques (See Figure 3), coupled with a concurrent increase in demand due to
technological advances such as automotive transport, flight and electrical power,
provided fertile economic conditions for the second oil boom. This led to annual world
consumption of billions of tons of petroleum within 100 years of Drake’s first well.
Figure 2: Advances in Oil Exploration
Concern over the finite lifetime of fossil fuel reserves (estimated at 30 years in 1975),
together with the increasing rate of consumption, and the disproportionate distribution
of known world reserves, contributed to the so-called ‘Energy Crisis’ in the early 1970s.
However, exploration and production improvements led to significant oil finds in various
other geographical locations in the last quarter of the 20th century, with very significant
finds in the North Sea, Africa, the Far East, South America and Alaska.
Figure 3: Advances in Oil Production Technology
Environmental concerns have provided more recent challenges to petroleum utilisation,
with significant international pressure to move away from reliance on fossil reserves
such as petroleum products to more sustainable energy options.
International summits during the 1990s (the ‘Rio’ and ‘Kyoto’ summits) have attempted
international co-ordination of policy. However, whilst the move towards use of
sustainable energy forms is inevitable, liquid fuels are still likely to play a dominant role
in the first half of the 21st Century.
4. Petroleum as a source of industrial fuels
In CF62, petroleum derived industrial fuels are broadly categorised as Petroleum
Distillate Fuels, essentially “light” fuels, and a range of Petroleum Residual Fuels
broadly described as light, medium and heavy oils. These two categories comprise a very
wide range of fuels, which are detailed in CF233, along with information on the
derivation of these fuels from crude petroleum.
Glossary terms
Bio-oils – Liquid fuels processed from biomass materials, for example wood chips, which
are being developed as automotive or industrial fuels.
Combustion – The act or process of burning; in which principally the carbon and
hydrogen components of the material being burned are oxidised releasing heat
Crude Oil – A liquid fossil fuel, also known as crude petroleum, that occurs naturally in
sedimentary rocks and consists of a mixture of hydrocarbons and hydrocarbon derivates
ranging from methane to heavy bitumen
Crude Petroleum –A liquid fossil fuel, also known as crude oil, that occurs naturally in
sedimentary rocks and consists of a mixture of hydrocarbons and hydrocarbon derivates
ranging from methane to heavy bitumen
Fossil Fuel – Organic fuels obtained from organic matter natural maturation during long
periods of time (coal, oil, natural gas).
Petroleum Distillate Fuels - Relatively light liquid fuels obtained from the fractional
distillation of crude petroleum.
Petroleum Residual Fuels - Heavy products from distillation and other petroleum
refining processes which may be fired as a liquid fuel.
Renewable Energy Sources – Energy sources that are derived from the sun or other
natural processes; including the energy obtained by processing sustainable biomass (i.e.
excluding peat), solar energy, geothermal energy, wind energy, hydro energy, energy
from ocean thermal energy, ocean wave and tidal energy, and the biodegradable portion
of waste.
Keywords
boilers; coke; combustion; crude; energy; exploration; fossil; fuel; furnaces; gas;
gasoline; heating; industrial; kerosene; liquid; marine; oil; petroleum; power; residual;
residue; technology; wells.
Related Combustion Files
62 – What are industrial fuels?
233 – What are the main petroleum fuel products?
Sources
[1] Goodger E.M. ‘Hydrocarbon Fuels’, 1975
[2] Lefebvre A.H. ‘Atomisation and Sprays’, 1989
[3] Goodger E.M. Journal of Institute of Energy, 1997
[4] Kempe's Engineers Year-Book, Ed. J Hall Stephens (2002)
[5] Combustion of Sprays of Liquid Fuels, Alan Williams (1976)
[6] Robert H. Perry-Don W.G, Perry’s Chemical Engineers’ Handbook, 1976
[7] Elsevier science publishing, Shell International Petroleum Company, The Petroleum
Handbook, 1983.
Acknowledgements
The author would like to thank Peter Kay (Ricardo-Sponsored PhD Student) and Anthony
Giles (EU/EPSRC sponsored PhD student) for their assistance.
File Placing
[Fuels and Comburents]; [Introduction to Fuels]; [Basics]
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