What is Oil?

In the context of mining, oil refers to petroleum or crude oil. This complex mixture of hydrocarbons (molecules of hydrogen and carbon) occurs naturally and is derived from organic materials that have developed for centuries. Along with coal and natural gas, oil part of the three major ‘fossil fuel’ groups - a general term for a type of rock, or rock derived product, that can be burned for fuel.

The refined products produced from crude oil serve as significant resources for many operational practices in a variety of industries. Main oil products that are commercially-available include petrol, diesel oil, refinery gases, kerosene (airplane fuel), and bitumen (for covering roads).

Image Credits: Lukasz Z/shutterstock.com

How Is Oil Formed?

Petroleum is considered a fossil fuel because it is formed from the remains of marine organisms such as algae and plankton, which become trapped in sea bed sediments and subjected to intense heat and pressure as they are buried in a sedimentary basin. Such heat and pressure cause alterations within the organic matter, eventually turning the material into kerogen, a mixture of organic particles containing carbon, hydrogen, and oxygen, as well as traces of nitrogen and sulfur. When the temperature level known as ‘oil window’ (between 60o to 100o Celsius) is reached, crude oil hydrocarbons are released. Rocks containing significant percentages of kerogen are known as ‘source rocks’ for oil. This process, leading to the production of crude oil, takes about 100 million years to complete.

When Does Oil Become Profitable?

The oil reserve under the ground has to be commercially-viable for mining to take place (i.e., the amount of the oil that can be extracted using available mechanisms must exceed the cost of the extraction and production process). Oil only becomes profitable once it has migrated from the source rock to a ‘trap’ or reservoir, a place where the oil may be retained and extracted at the same time.

These traps are formed in porous and permeable rocks, enabling oil to travel easily within the area. Often, oil seeps out of these traps as a result of unlimited travel; however, when an impermeable seal is present, oil would not be able to escape to the surface. These traps may be structural (e.g., oil is trapped due to rock folding) or stratigraphical (e.g., oil is trapped because the overlying rock is impermeable and forms a seal or ‘cap rock’).

Profitable oil reserves would, therefore, require a source rock, a reservoir, and a seal.

A Brief History Of Oil Extraction

Petroleum oil has been known for at least the entirety of recorded history, but mass commercial production only took hold in 1859 after the drilling of a well in Pennsylvania, a project coordinated by Edwin Drake.

Drake, an unemployed railway conductor, led the operation near Titusville, Pennsylvania after an initial attempt in oil extraction had ended in failure and bankruptcy. Using a steam-operated drill and a wooden rig, Drake drilled at least 70 feet to come into contact with oil, which was then pumped from the ground. This discovery catalyzed oil extraction activities in North America. The first giant oil field was started in the Gulf Coast at the Spindletop gusher, a mechanism that rose up to 60 meters in the air and blew out an estimated 100,000 barrels of oil per day within nine days.

An iconic image of Drake (right) in front of his wooden oil rig. Image Credit: PA Dept. of Conservation and Natural Resources.

A photograph of Spindletop, Texas throwing crude oil into the air. Original Image: John Trost

How Is Oil Extracted And Processed Today?

Petroleum oil has been known for at least the entirety of recorded history, but mass commercial production only took hold in 1859 after the drilling of a well in Pennsylvania, a project coordinated by Edwin Drake.

Drake, an unemployed railway conductor, led the operation near Titusville, Pennsylvania after an initial attempt in oil extraction had ended in failure and bankruptcy. Using a steam-operated drill and a wooden rig, Drake drilled at least 70 feet to come into contact with oil, which was then pumped from the ground. This discovery catalyzed oil extraction activities in North America. The first giant oil field was started in the Gulf Coast at the Spindletop gusher, a mechanism that rose up to 60 meters in the air and blew out an estimated 100,000 barrels of oil per day within nine days.

Where Is Oil Found?

While oil is found globally, some countries have relatively larger supplies than others. Due to the high cost and demand for oil, some nations have even engaged in wars over the last few centuries in order to gain control of oil activity in certain regions. Areas in which major oil fields sit include the Middle East, Gulf of Mexico, North Sea, Siberia, West Africa, North Africa, Indonesia, and The Caspian. Among these regions, Saudi Arabia has the largest oil reserve with 260 billion barrels.

More than 75% of the global oil supply is controlled by the Organisation of Petroleum Exporting Countries (OPEC). Created in 1960, OPEC is an organization that aims to standardize oil policies in 12 major oil-producing nations. The organization is heavily influential in controlling the global supply and cost of petroleum.

OPEC member-states include Algeria, Angola, Ecuador, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, United Arab Emirates, and Venezuela.

How Much Oil Is Left?

The production of petroleum oil rose rapidly in the last half of the 20th century and is currently produced at a rate of roughly 28 billion barrels or 42 gallons per year. The total volume of extractable oil left on the planet is currently estimated at around 1000 billion barrels. This estimate is in line with current discoveries of new oil reserves in various parts of the globe.

Barrels of proven oil reserves left on the planet in 2012. Information from CIA world factbook. Image created by Wikipedia user for public use.

Oil is a finite resource that is heavily utilized in a variety of applications. The peak production of oil in the United States was in 1970, but it has slowly decreased since then. The demand for petroleum, however, has risen. Worldwide oil production in the 21st century continues to move upward due to widespread applications and new activities.

Currently, the rate at which humans consume oil is more than 1 million times the speed at which it is naturally formed. The heavy reliance that humans have on this natural resource is a source of concern, leading many companies and governments to advocate a gradual shift towards more sustainable fuel solutions. However, attempts to reach a compromise between states are often limited by short-sighted personal and political agendas.

Production Rates of main oil-producing countries. Image Source: Energy Information Administration / Annual Energy Review 2006

There are reserves of oil that are currently unavailable but may become extractable with advancements in technology. This includes oil trapped in tar sands, heavy oils, and oil shale. When these sources become accessible, they will postpone the decline in oil production.

The current rate of oil use and activity estimates that the planet will run out of useable petroleum at some point before 2200.

Resources

This article was updated on 5th March, 2019.

G.P. Thomas

Written by

G.P. Thomas

Gary graduated from the University of Manchester with a first-class honours degree in Geochemistry and a Masters in Earth Sciences. After working in the Australian mining industry, Gary decided to hang up his geology boots and turn his hand to writing. When he isn't developing topical and informative content, Gary can usually be found playing his beloved guitar, or watching Aston Villa FC snatch defeat from the jaws of victory.

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