How oil is formed in the ground


  • 1 Petroleum
  • 2 The oil will be in the ground
    • 2.1 Organic theory
    • 2.2 Inorganic theory
  • 3 Petroleum classification
  • 4 Petroleum products
  • 5 References


Known oil ( in English: Petroleum) that the mixture complex of hydrocarbons that exist on a solid image, or gaseous, liquid or in the ground, and although reference this concept usually liquid image, which is also called the oil name of the crude, but it includes natural gas, The solid form is known as bitumen. [1]

Petroleum is in the ground

Organic theory

Biogenic theory, which explains the formation of petroleum, is the most acceptable theory among geologists, as they believe that it was formed as a result of pressure and heating to which organic matter was subjected over the course of geological time. According to this theory, the oil has gone through many stages, which : [2] [3]
  • Oil consists of the remains of plankton, algae and plants that existed millions of years ago, and were buried in large quantities on the sea floor or lake under conditions of lack of oxygen.
  • The organic matter mixed with mud is buried under many layers of sediments over the geological time after the ancient seas dry up.
  • Organic materials are exposed to high levels of heat and pressure , which causes them to be changed chemically to a waxy substance called kerogen. This substance then turns into various forms of hydrocarbons such as coal, natural gas , and peat with high temperature in a process known as cracking. (English: catagenesis).
  • Hydrocarbons sometimes migrate upward through adjacent rock layers, since most of them are lighter than rocks or water until they are trapped inside porous rocks called reservoirs (under the reservoirs) under impermeable rocks, and the concentration of hydrocarbons in the traps forms oil fields, and the oil may turn To natural gas through the thermal cracking process.

Inorganic theory

Abiogenic theory constitutes the minority opinion, especially for geologists, which was adopted by the astronomer Thomas Gould based on the beliefs of Russia, and in particular from Nikolai Kudryavtsev's studies, and this theory says that hydrocarbons of geological origin exist on this planet . [2]

Petroleum classification

Petroleum or crude oil can be classified into several categories, including the following: [3]
  • Classification of oil according to its geographical location: Oil can be classified according to its geographical location. Despite drilling wells all over the world, there are three main sources for it that are reference points for pricing and arranging other oil supplies, which are:
    • Brent Crude: Brent Crude constitutes a total of 15 oil fields distributed between Scotland and Norway in the North Sea, which provide oil to most of the European countries.
    • WTI Crude: West Texas Intermediate is light, of very high quality, and is a provider to most North American countries.
    • Dubai Crude: This type is also known as Dubai-Oman Crude, which is produced in Dubai, in addition to its production in the State of Oman recently. To Asia.
Note: The Organization of Petroleum Exporting Countries is another important source of crude oil , called the abbreviation OPEC, as it is a reference to the average price in the twelve member countries such as Algeria, Ecuador, Iran, Angola, Iraq, Libya, Kuwait, Saudi Arabia, and others.
  • Classification of oil according to the content: Petroleum can be classified according to the percentage of sulfur content in it, as the oil containing more than 0.5% of the sulfur is called sour petroleum, while the oil that contains less than 0.5% of it is sweet (in English: sweet), which is more valuable As it is less harmful to the environment and does not require much refining.
  • Classification of oil according to density: The American Petroleum Institute (API) has developed a classification system for petroleum, which depends on measuring the density of petroleum liquid compared to water, and is called the gravity (API), as it classified petroleum into light, heavy, and light oil is higher production of hydrocarbons, so It is preferred, while heavier oil contains higher concentrations of sulfur and minerals , which require additional refining processes.

Petroleum products

Petroleum products are defined as the substances that are derived from petroleum after treatment in its refineries, and which consist of complex mixtures, unlike petrochemicals (English: petrochemicals) that are composed of pure and specific chemical compounds , and it is indicated that most of the oil is transferred to petroleum products, which includes Many fuels, as the materials made from byproducts of petroleum waste reach more than 6000 materials such as perfumes, fertilizers, wax, soaps, and pesticides , [4] . Examples of types of refined petroleum products include the following: [5]
  • Kerosene: Kerosene (English: Kerosene) is a lightweight, rapidly spreading and evaporating material, in addition to being easy to flow.
  • Lubricating oils: Lubricating Oil is a medium-weight petroleum product that is easy to spread if processed immediately and is also easy to flow.
  • Gasoline: The gasoline ( in English: Gasoline) material easy flow, lightweight, fast - spreading, as it can evaporate in a few hours entirely in natural conditions, and is gasoline capable of being biodegradable, but it is more toxic than crude oil.
  • Crude Oil No. 2: This fuel is a non-volatile, easy to separate material, in addition to being lightweight and easy to flow.
  • Crude No. 4: It is a type of fuel that consists of an easy-to-flow medium-weight material that can be readily dispersed if processed immediately.
  • Crude No. 5: This fuel is considered a volatile, medium-to-heavy material.
  • Crude No. 6: This petroleum product is a heavy material that requires pre-heating for use, and is hard to pump, less volatile, and difficult or impossible to separate.

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