1. Why is oil called "the blood of industry"?
Petroleum is an important power fuel in industrial society, and its many advantages are incomparable to other fuels. For example, in terms of physical properties, oil is a liquid that can flow, its specific gravity is less than that of water, and it is easy to exploit, occupy a small volume and transport. Gasoline and diesel oil extracted from crude oil have the highest energy density per unit volume among all liquid fuels at present. Although natural gas and hydrogen fuel release more heat per unit mass than gasoline and diesel, it often means that more space capacity is needed, so it is not as convenient as gasoline and diesel in storage and transportation. In addition, gasoline and diesel oil can meet the requirements of internal combustion engines because they are fully burned and have no ash (see figure 1- 1). Therefore, oil is an important power fuel in sea, land and air transportation and factory production. In modern national defense, the fuels used for new weapons, supersonic aircraft, missiles and rockets are all extracted from petroleum.
Figure 1- 1 Comparison of energy density of several typical fuels (compared with gasoline energy density of 1) Source: us energy information administration and CITIC Futures Research Department. Petroleum is also an important chemical raw material. Modern organic chemical industry must comprehensively utilize oil, coal, natural gas and other resources. Hundreds of useful substances can be extracted from oil, and their economic value far exceeds the economic significance of burning as fuel. The petrochemical industry can produce hundreds of chemical products, such as plastics, synthetic fibers, synthetic rubber, synthetic detergents, dyes, drugs, pesticides, explosives and fertilizers. Petroleum and petroleum products are not only necessities for people's livelihood, but also important materials for modern industry, agriculture and national defense. Modern industry is inseparable from oil, just as human body is inseparable from blood. Therefore, oil is called "the blood of industry". It is this characteristic of oil that led the European and American groups with "Seven Sisters" as the core to compete for oil on a global scale in the early 20th century.
Second, what is crude oil?
Crude oil, also known as "black gold", is a liquid or semi-solid combustible substance. Like coal and natural gas, it is a non-renewable fossil fuel and one of the important primary energy sources in the world. It is composed of different hydrocarbons, and its composition is very complicated, mainly including oily (hydrocarbon), asphaltene (dark brown or black brittle solid matter), colloid and carbon (a non-hydrocarbon).
The physical properties of crude oil vary with the origin and reservoir, and there is no fixed chemical composition, so there is no fixed physical constant. Generally speaking, crude oil has a density of 0.8~ 1.0g/cm3, a wide range of viscosity, a great difference in freezing point (-60℃~32℃), a boiling point above 500℃ at room temperature, and is soluble in various organic solvents, but insoluble in water, but can form an emulsion with water.
The chemical elements that make up crude oil are mainly hydrocarbons composed of carbon and hydrogen. The proportion of carbon in crude oil is 83%~87%, hydrogen is 1 1%~ 14%, and the rest is sulfur (0.06%~0.8%), nitrogen (0.02%~ 1.7%) and oxygen (.
Although the basic elements that make up crude oil are similar, there are many kinds of crude oil produced in different places and strata. In crude oil from different sources, the structure and proportion of various hydrocarbons vary greatly, among which straight-chain alkanes, cycloalkanes and aromatics are the main ones, and the proportion is usually above 90%. However, the content of different hydrocarbons often varies greatly, and the proportion of non-hydrocarbons, that is, compounds containing sulfur, nitrogen and oxygen, is very small. Crude oil also contains metal salts, mainly a mixture of chlorides such as sodium, calcium and magnesium, and the salt content is usually 0.02%~0.055%. Therefore, after crude oil is mined underground, it needs dehydration and desalination before it can be processed.
Crude oil is a heterogeneous commodity, and the quality of crude oil from different places often varies greatly, so it is difficult to standardize crude oil like metals and other industrial products. The characteristics of diversified crude oil quality are also reflected in the production, trade, processing and pricing of crude oil.
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Color of oil
3. What is the difference between crude oil and petroleum?
People are used to equating oil with crude oil. In fact, this is not a rigorous statement. 1 1 The World Petroleum Congress formally defined terms such as oil in 65438:
Petroleum: refers to the natural mixture of gaseous, liquid and solid hydrocarbons.
Crude oil: one of the basic types of oil, which is stored in underground reservoirs and is liquid at normal pressure, including some liquid non-hydrocarbon components. Generally speaking, the viscosity of crude oil in the reservoir state does not exceed 10mPas.
Natural gas: one of the basic types of petroleum, which is gaseous or dissolved in crude oil under formation conditions and gaseous at normal temperature and pressure after exploitation. Natural gas may also contain a small amount of non-hydrocarbon components.
Natural gas liquid: refers to a part of natural gas recovered in liquid form in natural gas treatment unit, mainly including natural gas gasoline and condensate oil, and may also contain a small amount of C 1~C4 alkanes and non-hydrocarbon components.
Natural tar: refers to petroleum deposits, which are semi-solid or solid, such as Canadian oil sands. The viscosity is greater than 10mPas at normal temperature and pressure, and it often contains a small amount of non-hydrocarbon substances such as sulfur, nitrogen, oxygen and metals.
Although the definitions of oil and crude oil are relatively uniform at the industry level, there are still some differences in definitions among countries. The key question is whether natural gas liquid and condensate (related to oil fields) and oil flow extracted from natural tar and asphalt meet the definition of crude oil. At present, the international energy agency (IEA), the Organization of Petroleum Exporting Countries (OPEC) and other mainstream official institutions have not included natural gas condensate, so long as condensate can be separated from industrial oil flow, it should also be excluded; However, in the definition of us energy information administration (EIA), condensate oil produced by some mines is also included in the category of crude oil.
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What is condensate?
Condensate refers to the liquid component condensed from the associated natural gas in condensate gas field or oil field, also known as natural gasoline. The characteristic of condensate oil is that it exists in gas phase underground, which is called condensate gas, and it is liquid after it is produced to the pool surface. Its main component is a mixture of C5~C7 hydrocarbons, and contains a small amount of hydrocarbons, sulfides and other impurities greater than C8. Most of its fractions are at 20℃~200℃, which has good volatility. Condensate oil can be directly used as fuel and is also a high-quality raw material for oil refining industry. Generally, the naphtha yield is 60%~80%, the diesel yield is 20%~40%, and the API value is above 50 degrees. The boundary between it and ultra-light crude oil is not obvious.