Crude oil is oil that is not yet refined to produce useful products. It consists of a mixture of a wide variety of chemicals, most of which are hydrocarbons. Hydrocarbons are compounds formed from carbon and hydrogen atoms that combine in a multitude of ways to create gases, liquids and solids. These mixtures of various hydrocarbons exist underground in porous deposits known as reservoirs, embedded in sedimentary rocks, and in tar (oil) sands close to the surface of the earth.
Besides hydrocarbons, crude oil also contains a number of other components, some of which are potentially economically useful, while others can be harmful to humans or damaging to the environment. These components can be sulfur compounds, free hydrogen, nitrogen compounds, and a variety of high-density, solid hydrocarbons. An analysis of the characteristics of any particular grade of crude is reported in an "assay", which is a listing of the chemical components and physical properties comprising the crude oil, and which determines its quality and value. Assays can vary widely in the measurements of the components listed, often depending on the field from which the oil was extracted.
Global Oil Reserves
Reserve values are in billion barrel units.
|United Arab Emirates||98|
Source: EIA Beta International
The above chart is for proved oil reserves in the specified countries. A "proved" reserve is one which has at least a 90% probability of production, within the constraints of modern technologies, current costs of production, and political conditions.
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Global Oil Production
There are approximately 100 countries that produce crude oil. Globally in 2016, the top five crude oil producing countries were Russia (13%), Saudi Arabia (13%), USA (11%), Iraq (6%), and Iran (5%).
USA Oil Production
Crude oil is produced in 31 U.S. states and in U.S. coastal waters. In 2016, about 65% of U.S. crude oil production came from five states:
- North Dakota—12%
In 2016, about 18% of U.S. crude oil was produced from wells located offshore in the federally administered waters of the Gulf of Mexico.
Primary petroleum products derived from crude oil include:
- Liquified petroleum gas (LPG)
- Jet aircraft fuels
- Diesel fuel
- Fuel oils
- Lubricating oils
- Paraffin wax
- Asphalt and tar
- Petroleum coke
In addition to the products listed above, a wide variety of other products can be extracted from crude oil. These consist of a very large number of commercial products, from chemicals for the chemical industry to the materials used to create the clothes we wear.
Oil Refineries are huge industrial complexes with a wide variety of components, all of which are required for the difficult task of extracting, purifying, and storing the very wide variety of products that are derived from crude oil.
The effects that oil use has on the environment take many different forms. Some are accidents that result in local contamination. Some are intrinsic to the processes of exploration, drilling and production. Probably the most important effect that oil use has on the environment is the vast amount of carbon dioxide and other greenhouse gasses that are released into the atmosphere, resulting in global warming.
The world's ten largest oil companies by reserves are all National Oil Companies (NOC). That is, they are owned by the countries in which they are headquartered. Following is a list of those top ten companies:
- Saudi Aramco
- Qatar Petroleum
- Iraq National Oil Company
- National Oil Company of Libya