It is customary to refer to unprocessed petroleum as crude oil. A viscous oily liquid that is dark brown with green fluorescence and has a special odor. It is a mixture of various liquid hydrocarbons such as alkanes, cycloalkanes, aromatic hydrocarbons and alkenes.
The main components are carbon and hydrogen, accounting for 83-87% and 11-14% respectively; there are also small amounts of sulfur, oxygen, nitrogen and trace amounts of phosphorus, arsenic, potassium, sodium, calcium, magnesium, nickel, iron, Elements such as vanadium. The specific gravity is 0.78~0.97, the molecular weight is 280~300, and the freezing point is -50~24℃. After crude oil is refined and processed, various fuel oils, solvent oils, lubricating oils, greases, paraffin, asphalt, liquefied gas, aromatics and other products can be obtained, providing fuel, raw materials and chemical products for various sectors of the national economy.
On October 27, 2017, the World Health Organization’s International Agency for Research on Cancer released a preliminary list of carcinogens for reference. Crude oil is included in the list of Category 3 carcinogens.
History development #
Humanity officially entered the oil age in 1867. This year, the proportion of petroleum in the primary energy consumption structure reached 40.4%, while the proportion of coal dropped to 38.8%. Petroleum is the blood of industry. Since the founding of the People’s Republic of China, Chinese society has rapidly moved from an agricultural economy to an industrial economy, and the demand for energy has Climbing steadily. Oil consumption soared from more than 1 million tons at the beginning of the founding of the People’s Republic of China to 490 million tons in 2012. The latter was nearly 500 times the former, ranking second in the world.
Oil and gas resources support China’s rapid economic development. The growth in oil demand and the expansion of oil trade result from the large-scale use of oil in industrial production. Before World War I, oil was mainly used for lighting, and the major oil-producing countries, the United States and Russia, were also major consumers. In World War I, the strategic value of oil has initially emerged. Because oil has high combustion efficiency and is lightweight, it has great strategic significance for improving the combat effectiveness of the army.
In the 1920s, oil demand and trade expanded rapidly as oil became the power source for internal combustion engines. According to Wang Yadong’s statistics, by 1929 the oil trade volume had reached 1.17 billion US dollars. During this period, the flow of international oil cargo mainly flowed from the United States and Venezuela to Western Europe.
At the same time, Soviet oil was rapidly restored and developed. By the end of the 1930s, the United States and the Soviet Union had become major oil exporters, and international oil trade began to occupy a prominent position in global energy trade, promoting the rapid growth of international energy trade and shaking the dominant position of coal in the international energy market. status. During World War II, oil played an important role. The United States became the main energy supplier to the Allies during World War II.
After World War II, the United States once controlled 2/3 of the world’s crude oil production. From the first oil well drilled in Pennsylvania in 1859 to the period after World War II, the world’s energy landscape was called the “Gulf of Mexico Era.” Wang Yadong believes that the formation and development period of the “Gulf of Mexico Era” was also a period when the United States’ political, economic and military strength continued to expand, and it finally established its hegemony in the Western world. This period almost coincided with the development of domestic oil in the United States. The United States’ control of oil during the “Gulf of Mexico Era” helped consolidate the United States’ position in the world’s political and economic landscape. Oil has become an important booster for the United States in establishing world hegemony.
On August 8, 2023, China National Petroleum Corporation learned that the solar thermal system in Block III of its Jilin Oilfield Xinli Oil Production Plant was officially connected to the grid and put into operation, marking the completion and operation of the zero-carbon demonstration zone for Asia’s largest onshore oil production platform cluster. The demonstration area produced China’s first barrel of “zero-carbon crude oil.”
In 2023, the total domestic crude oil and natural gas production will be 416 million tons (oil equivalent), a year-on-year increase of 3.9%. Among them, crude oil production has increased for the fifth consecutive year, returning to 200 million tons in 2022 and growing again by 2% to 209 million tons .
nature #
The properties of crude oil include physical properties and chemical properties. Physical properties include color, density, viscosity, freezing point, solubility, calorific value, fluorescence, optical rotation, etc.; chemical properties include chemical composition, component composition, impurity content, etc.
physical properties #
The relative density of crude oil is generally between 0.75-0.95, with a few greater than 0.95 or less than 0.75. Those with a relative density of 0.9-1.0 are called heavy crude oil, and those with a relative density less than 0.9 are called light crude oil.
Crude oil viscosity refers to the internal friction resistance caused by crude oil flowing. The viscosity of crude oil depends on temperature, pressure, dissolved gas volume and its chemical composition. As the temperature increases, the viscosity decreases, as the pressure increases, the viscosity increases, as the amount of dissolved gas increases, the viscosity decreases, and as the light oil component increases, the viscosity decreases. The viscosity of crude oil varies greatly, generally between 1-100mPa·s. Crude oil with high viscosity is commonly known as heavy oil. Heavy oil becomes more difficult to develop due to poor fluidity. Generally speaking, crude oil with higher viscosity is also denser.
The temperature at which crude oil cools from a liquid to a solid is called the freezing point. The freezing point of crude oil is approximately between -50°C and 35°C. The level of the freezing point is related to the component content in the petroleum. A high content of light components will result in a low freezing point. A high content of heavy components, especially a high content of paraffin, will result in a high freezing point.
chemical properties #
Crude oil is a mixture of various liquid hydrocarbons such as alkanes, cycloalkanes, aromatic hydrocarbons and olefins. The main components are carbon and hydrogen, accounting for 83-87% and 11-14% respectively; there are also small amounts of sulfur, oxygen, nitrogen and trace amounts of phosphorus, arsenic, potassium, sodium, calcium, magnesium, nickel, iron, Elements such as vanadium.
Wax content refers to the percentage of paraffin and ozokerite contained in crude oil under normal temperature and pressure conditions. Paraffin is a white or light yellow solid composed of higher alkanes with a melting point of 37°C-76°C. Paraffin wax is dissolved in petroleum in a colloid form underground and can be precipitated from petroleum when pressure and temperature are reduced. The temperature at which the paraffin in the formation crude oil begins to crystallize and precipitate is called the wax precipitation temperature. The higher the wax content, the higher the wax precipitation temperature.
The wax precipitation temperature is high, and oil wells are prone to wax formation, which is detrimental to oil well management.
Sulfur content refers to the percentage of sulfur (sulfide or elemental sulfur) contained in crude oil. The sulfur content in crude oil is small, generally less than 1%, but it has a great impact on the properties of crude oil, has a corrosive effect on pipelines, and is harmful to human health. Depending on the sulfur content, it can be divided into low-sulfur or sulfur-containing petroleum.
Gum content refers to the percentage of gum contained in crude oil. The gum content of crude oil is generally between 5% and 20%. Colloid refers to polycyclic aromatic hydrocarbon compounds containing oxygen, nitrogen, sulfur and other elements in crude oil with a relatively large molecular weight (300-1000), which are dissolved in crude oil in a semi-solid dispersed state. Gum is easily soluble in organic solvents such as petroleum ether, lubricating oil, gasoline, and chloroform.
The asphaltene content in crude oil is small, generally less than 1%. Asphaltene is a black solid substance with a high molecular weight (more than 1000) and a polycyclic structure. It is insoluble in alcohol and petroleum ether and easily soluble in benzene, chloroform, and carbon disulfide. When the asphaltene content increases, the quality of crude oil deteriorates.
The hydrocarbon components in crude oil are mainly divided into alkanes, cycloalkanes, and aromatic hydrocarbons. According to the different hydrocarbon components, it can be divided into three categories: paraffin-based petroleum, naphthenic-based petroleum and intermediate-based petroleum. Paraffin-based petroleum contains more alkanes; naphthenic-based petroleum contains more naphthenes and aromatic hydrocarbons; intermediate-based petroleum is somewhere in between. Most of the crude oil mined in China is based on low-sulfur paraffin. Crude oil from Daqing and other places falls into this category. Among them, the most representative Daqing crude oil has low sulfur content, high wax content and high freezing point. It can produce high-quality kerosene, diesel, solvent oil, lubricating oil and commercial paraffin. Shengli crude oil has high colloid content (29%), large specific gravity (about 0.91), high wax content (about 15-21%), and is a sulfur-containing intermediate base. The gasoline fraction has good lead sensitivity and is rich in naphthenes and aromatic hydrocarbons, so it is a good raw material for reforming.
Storage and transportation #
store
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The main ways of storing crude oil and oil products are bulk storage and packaged storage. Packaged storage refers to storage in the form of standard barrels. Bulk storage refers to storage in the form of oil storage tanks. Oil storage tanks can be divided into metal oil tanks and Non-metallic oil tanks and metal oil tanks can be divided into vertical cylindrical and horizontal cylindrical shapes. Depending on the construction method of the oil depot, bulk crude oil or oil products can also be stored in several ways, such as above-ground oil storage, semi-underground oil storage and underground oil storage, water-sealed stone cave oil storage, and underwater oil storage. But no matter which storage method is used, the storage of crude oil, especially oil products, should meet the following basic requirements:
(1) Prevent deterioration
During the oil storage process, to ensure the quality of the oil, attention must be paid to: reducing the effects of temperature, air and moisture, sunlight, and metal on the oil.
(2) Reduce loss
The usual practices in oil depots are: use floating roof oil tanks and internal floating roof oil tanks; use breathing valve baffles under the oil tank breathing valves; spray water to cool down.
(3) Improve the safety of oil storage
Due to the high fire risk and explosion risk of oil products, it is necessary to reduce the explosion sensitivity of oil products and use materials with good flame retardant properties.
loading and unloading
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The loading and unloading of crude oil and oil products is nothing more than the following forms: railway loading and unloading, water transport loading and unloading, road loading and unloading and direct pipeline transportation. According to the different properties of the oil, it can be divided into light oil loading and unloading and viscous oil loading and unloading; considering the oil loading and unloading process, it can be divided into loading and unloading, bottom unloading, gravity flow and pumping. However, except for direct pipeline transportation, no matter what loading and unloading method is used, the loading and unloading of crude oil and oil products must meet the following basic requirements:
(1) It must be completed through special facilities and equipment.
Special facilities for loading and unloading crude oil and oil products mainly include: special railway lines and oil tankers, oil terminals or berthing points, tankers, trestles or operating platforms, etc.; special equipment mainly include: loading and unloading oil crane pipes, oil collection pipes, oil pipelines and Oil pumps, hair oil filling equipment, sticky oil heating equipment, flow meters, etc.
(2) Must be completed in a dedicated work area.
There are dedicated operating areas for the loading and unloading of crude oil and oil products. These dedicated operating areas are usually equipped with isolation facilities to isolate them from the surrounding environment, and must meet strict fire protection, explosion protection, lightning protection, and anti-static requirements.
(3) It must be completed by professional and technical personnel who have received special training.
(4) There are strict requirements on the time and speed of loading and unloading.
output
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Crude oil has a certain viscosity. Especially when the temperature is low, the oil stored in large oil storage tanks is not easy to be output directly. It must be heated to a certain extent to achieve the purpose of raising the temperature of the crude oil and improving the fluidity of the crude oil.
The current methods of heating crude oil storage tanks are mainly divided into two types, one is coil heating of the entire tank, and the other is local rapid heating.
The whole tank heating method is a crude oil heating method that is currently relatively simple to apply and widely priced, while local rapid heating has the characteristics of better energy saving and high heating efficiency.
use
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Crude oil products can be divided into six categories: petroleum fuel, petroleum solvents and chemical raw materials, lubricants, paraffin, petroleum asphalt, and petroleum coke. Among them, the output of various fuels is the largest, accounting for nearly 90% of the total output; the variety of lubricants is the largest, accounting for about 5%.
Crude oil products have a very wide range of roles and functions in social and economic development.
Crude oil products, mainly referring to gasoline, kerosene, diesel, heavy oil and natural gas produced by crude oil refining, are currently the main suppliers of major energy sources. The energy provided by crude oil products is mainly used as fuel for cars, tractors, airplanes, ships, boilers, and a small amount is used as civilian fuel.
Crude oil products are one of the pillars of the materials industry. Metals, inorganic non-metallic materials and polymer synthetic materials are known as the three major materials. The output of polymer synthetic materials provided by the world’s crude oil chemical industry is approximately 145 million tons. In addition to synthetic materials, petroleum products also provide the vast majority of organic chemical raw materials. Within the scope of the chemical industry, in addition to the chemical products provided by chemical minerals, the raw materials for petroleum product production are used in various departments.