Oil is a fossil fuel and liquid hydrocarbon used mainly for the production of transportation fuels and petroleum-based products.


What is Oil?

Oil, otherwise known as ‘petroleum or crude oil’, is a thick black liquid composed primarily of hydrogen and carbon. Oil also contains trace elements of sulphur, nitrogen and oxygen.1

Today’s oil deposits were formed millions of years ago, when dead marine organisms sunk to the bottom of the ocean and were buried under deposits of sedimentary rock. Subject to intense heat and pressure, these organisms underwent a transformation in which they were converted to oil over millions of years. 2 This process is similar to the process of natural gas formation, however oil forms under a limited range of temperatures while natural gas forms under a wider range. This limited range of temperatures is called the ‘oil window’. 3


Oil is found in specific underground rocks called reservoirs. The rocks have tiny spaces in them that allow them to hold water, natural gas and/or oil. Impermeable rocks called cap rocks surround the reservoir and trap oil in its place.4

Through exploratory activities such as seismic, well sampling, and subsurface mapping, geoscientists locate sites for oil drilling.

Oil is extracted from the reservoir by drilling a well and pumping it up the well. Once recovered, oil is transported by pipeline, ship, rail, or truck to a refinery where it undergoes a complex process that produces petroleum products such as gasoline, diesel, jet-fuel, home-heating fuel, lubricating oil and asphalt along with petrochemicals that are used to make common products such as plastic, drugs, synthetic fiber, soap and paint. Approximately 71 percent of global oil consumption is used to produce fuel to power transportation systems.5



Oil is a relatively abundant but is a non-renewable resource.  Supplies of conventional oil have been decreasing steadily, making unconventional production more common.

Oil’s benefits include its high energy density and versatility.  Oil is used to produce products like transport fuels and many other common products. While all these products are important to global society, approximately 71% of global oil consumption is used to enable transportation systems.

The production and use of oil also come with many social and environmental challenges. Producing oil causes land-disturbance sometimes in environmentally sensitive areas, although this varies greatly depending on the production techniques used.  The world’s oil-powered transportation systems contribute significantly to global greenhouse gas emissions and climate change. Additionally, control and trade of oil resources present many geopolitical tensions between nations and, on a more local level, between stakeholder groups and communities.

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Recent blog posts about Oil

External resources


International Association of Oil & Gas Producers


International Energy Agency

Organization of the Petroleum Exporting Countries

World Petroleum Council

Oil and Gas Council


US Oil & Gas Association

Illinois Oil & Gas Association

Society of Petroleum Engineer

The Petroleum Marketers Association of America

National Petroleum Council



BMI Research

The Petroleum Institute

University of Calgary

The Oxford Princeton Programme

University of Leeds

University of Dundee

British Columbia Institute of Technology

Canadian Energy Research Institute

Montan Universitat

Oil Center Research

Research Institute of Petroleum Industry

Politecnico di Torino


Universita Degli Studi Di Perugia


SPE Journal

Journal of Petroleum Technology



The virtual Geology Department Canda

Drilling Info

Technology Review (MIT) – Power and Politics in World Oil
The Economist – Oil and Gas
Global Policy Forum – Oil and Natural Gas in Conflict
Columbia – Center on Global Energy Policy
World Bank – The Great Plunge in Oil Prices: Causes, Consequences and Policy Response
American Petroleum Institute – Industry Economics
Oil and Gas Journal – Economics and Oil Market News
Oil and Gas UK – Economic Report 2014

OPEC Monthly Oil Market Report

Platts Real Time Oil Market Data

TEEIC – Potential Impacts of Oil and Gas Production
Kharaka and Dorsey – Environmental issues of petroleum exploration and production
UNESCO – Environmental Impacts of the Oil Industry
Scottish Government Fisheries Research Center – Environmental Impacts
State of the Environment Norway – Environmental Impacts of Oil and Gas activities
National Oceanic and Atmospheric Administration – Effects of Oil and Gas Activities in the Arctic Ocean
IHS – Oil and Gas
Oil and Gas Financial Journal – Analysis
Net News Ledger – Business Analysis
US EPA – Health effects of pollutants emitted from oil and natural gas prod. facilities
Earthworks – Oil and Gas Health Effects
Worcester Polytechnic Institute – The Health Effects of Oil Contamination
Journal of Environmental Sustainability – Towards Sustainability in the Oil and Gas Sector: Benchmarking of Environmental, Health, and Safety Efforts 
Ceres – Oil & Gas Producers
Castagra – Voluntary Sustainability Reporting
GreenBiz – Is there a greener side to Drilling for Oil?
Deep Blue Library – Oil Companies and Sustainability: More than just an Image?
Unep and The E&P Forum – Environmental Management
Financial Times – Oil – The big Drop

International Energy Agency (IEA) Oil Overview 

OilPrice.com – Types of Crude Oil 

  1. US EPA (n.d.) Water Energy. http://epa.gov/climatestudents/solutions/technologies/water.html
  2. BP (2008). Crude Oil and Natural Gas Formation.  http://www.bp.com/liveassets/bp_internet/bp_australia/bp_education_australia/STAGING/local_assets/downloads_pdfs/Module2_Crude_Oil_and_NaturalGas_Formation/bp_module02_int.pdf 
  3. Encyclopedia Britanica (2015). Oil Window. http://www.britannica.com/EBchecked/topic/426266/oil-window 
  4. Norman J. Hyne (2012). Nontechnical guide to petroleum geology, exploration, drilling, and production, Knovel Publishing.
  5. Energy Information Administration (2011). Primary energy consumption by source and sector. http://www.eia.gov/totalenergy/data/monthly/pdf/flow/primary_energy.pdf