China Petroleum Memorial Day | Why is oil so precious? Will it be replaceable in the future?

74 years ago today, the Yumen Oilfield was liberated, and the development of the petroleum industry in New China opened a new chapter. In 2021, PetroChina designated September 25, the day of the liberation of the Yumen Oilfield, as the "PetroChina Memorial Day". This time of year is a day for millions of oil workers. We often say that oil is precious, so why is it so precious? Can it be replaced in the future?

1. Why is oil so precious?

What makes oil so precious is the process of its formation, exploration, refining and transportation.

1. The formation of petroleum: a drop of "oil", billions of years

According to the current theory of oil and gas genesis, petroleum is mainly formed by organic genesis, that is, oil and gas are generated by organic matter such as animals and plants dispersed in sediments in geological history. Millions to hundreds of millions of years ago, after a large number of phytoplankton, algae and animals died, their remains and debris and other organic matter were deposited on the seabed or lake bottom and buried by other debris or chemical sediments.

Sediments continue to accumulate and are buried deep, forming sedimentary rocks through diagenesis.

The organic matter in sedimentary rocks undergoes complex biochemical and chemical changes during the burial process, forming kerogen through sapropelization and humification, which becomes the parent material for the generation of petroleum.

After kerogen is formed, as the burial depth increases, the temperature rises and oil and natural gas are formed through thermal degradation and thermal cracking.

Since the processes of sedimentation, diagenesis and burial are very slow, the process of oil formation is very long.

The process of oil formation (TuChong Creative)

2. Petroleum exploration: oil and gas reservoirs, no matter how hard you try

Due to the complex underground geological structure, the rock layers, structures, reservoirs, etc. in different regions vary, and the types of oil and gas reservoirs are also different. Oil exploration and exploitation face many challenges.

my country is one of the first countries in the world to discover, exploit and utilize oil and natural gas. The earliest record of oil can be found in the Book of Han, Geography, written by Ban Gu in 80 AD. Shen Kuo, a great scientist in the Northern Song Dynasty, mentioned in Mengxi Bitan that "oil is very abundant and is produced in the earth indefinitely", and named "petroleum" for the first time.

Oil and gas are stored in underground rocks. Through complex migration and aggregation processes, they are stored in underground places suitable for oil and gas accumulation - "traps", forming oil and gas reservoirs . Oil and gas reservoirs are usually buried several kilometers underground and are very hidden.

In addition to basic geological theory guidance, the search for oil and gas resources also requires some exploration technology. Geophysical exploration and drilling are the two most important ways . The principle of geophysical exploration is very similar to ultrasound and CT examinations in hospitals. It also detects underground geological structure information through sound waves, electromagnetic waves, etc. The most commonly used geophysical exploration method in oil exploration is seismic exploration, which artificially excites elastic waves on the surface, uses the differences in elasticity and density of underground media, observes and analyzes the propagation laws of seismic waves generated by artificial earthquakes underground, and infers the properties and morphology of underground rock formations. Seismic exploration is an important means of surveying oil and natural gas resources before drilling.

Oil drilling drilling (Picture Bug Creative)

3. Crude oil refining: Oil refining, pass several levels

First, crude oil needs to be distilled. After the equipment in the refinery heats the crude oil to a high temperature, through distillation, the components with different boiling points will be separated, forming gases, liquids and solids at different altitudes.

The liquid component is then hydrotreated to remove impurities such as sulfides and nitrides and to reduce the damage to the catalyst by sulfur- and nitrogen-containing compounds.

Then, through the method of catalytic cracking, some heavier long-chain hydrocarbons are cracked into short-chain hydrocarbons, and large molecular hydrocarbons are decomposed or converted into smaller molecules, which can increase the production of gasoline.

Next, the crude oil needs to go through catalytic reforming to increase its octane number, which is a measure of gasoline quality and is related to gasoline's anti-knock performance.

Finally, impurities and exhaust gas are treated through some processes to obtain clean gasoline.

Crude oil distillation scheme (TuChong Creative)

4. Oil transportation: Oil is difficult to transport and has high risks

The difficulties faced by oil transportation mainly include the following aspects:

1. Difficulties in transportation: Some areas of my country have high-viscosity crude oil that is easy to solidify. For pipeline transportation of high-viscosity crude oil, hot oil transportation technology and insulation pipeline structure are required, and drag reducing and pour point reducing agents are added during transportation.

2. High-pressure conditions: Long-distance pipeline oil transportation is usually under high-pressure conditions, which places high demands on transportation pipelines, storage tanks and other facilities. It is necessary to use high-performance materials and take corresponding measures to ensure the safety performance of the facilities.

3. Safety risks: Oil is a flammable and explosive substance, so oil transportation involves safety risks such as fire and explosion. In addition, oil leakage or accidental discharge can cause pollution to the soil, water and atmosphere.

Oil pipeline (TuChong Creative)

2. New technologies lend a helping hand to oil

1. Is it difficult to make oil? Here comes artificial oil!

Synthetic petroleum is a petroleum-like product made from solid or gaseous fuels, such as coal-to-oil through pyrolysis or syngas reaction. The main components of synthetic petroleum are also various hydrocarbons, and contain organic compounds such as oxygen, nitrogen, and sulfur. Although synthetic petroleum can replace natural petroleum to a certain extent, whether it can completely replace petroleum depends on many factors.

First, the preparation cost of artificial oil is currently high, while natural oil has abundant reserves and relatively low production costs. Secondly, there are problems such as environmental pollution and greenhouse gas emissions in the extraction and use of natural oil, and the production of artificial oil may also involve environmental impacts such as energy consumption and emissions. Therefore, artificial oil can replace oil to a certain extent, but achieving complete substitution requires further technological breakthroughs and comprehensive energy transformation .

2. Is it difficult to find oil? Be precise!

A vast amount of geophysical exploration data and drilling, logging, and oil and gas development data have been accumulated in the process of oil exploration and development. This has become a good opportunity to apply new technologies such as artificial intelligence and big data to "finding oil". For example, in oil exploration, intelligent inversion using a variety of exploration data has improved the accuracy of interpretation of faults, fractures, geological structures, etc., and automatic identification of high-quality reservoirs can be performed through machine learning methods and seismic and logging data. In terms of development, production parameters can be optimized through learning and training of historical production data of injection wells and development wells.

3. Is it difficult to transport oil? How to transport oil safely and environmentally friendly?

At present, oil transportation is still mainly based on pipeline transportation, so an efficient and safe pipeline system, such as improvements in insulation and anti-corrosion layers, and intelligent pipeline monitoring systems, is extremely important; at the same time, using electric drive technology instead of high-power gas or diesel engines to achieve propulsion can reduce environmental pollution and provide a more efficient and low-cost operation method.

As concerns about environmental impact continue to grow, designing and building environmentally friendly tankers has become a hot topic . These tankers reduce exhaust emissions and pollutant releases by installing exhaust gas purification devices, energy-saving equipment and corresponding treatment systems.

Liquefied natural gas (LNG ) ship technology is also an important option. This technology uses special ships to cool natural gas into liquid form so that it is easier to store and transport. Using liquefied natural gas as fuel, it has little air pollution after combustion, is a recognized clean energy source, and takes up little space.

At present, oil is still an important and irreplaceable energy source. As one of the fossil fuels, oil is one of the most important energy sources in the world, which can meet the energy needs of various industries and daily life; the oil industry plays an important supporting role in the development and stability of the national economy. The exploitation, processing and sales of oil resources have created a large number of employment opportunities, and oil trade has also become an important part of international trade.

However, with the increasing attention paid to environmental issues and sustainable development, people are gradually beginning to look for energy and materials that can replace oil, such as solar energy, wind energy, bioenergy, geothermal energy, etc. Therefore, the irreplaceability of oil is gradually being challenged.

Green waters and green mountains are invaluable assets. I believe that with the deepening of the concepts of environmental protection and sustainable development, clean energy will be fully utilized. By then, we will no longer see yellow sand and haze. People can enjoy the blue sky and fresh air and live comfortably on this beautiful blue planet.

Author: Zhu Chuanqing, Professor, China University of Petroleum (Beijing)

Reviewer: Jia Shaohui, Senior Engineer, National Petroleum and Natural Gas Pipeline Network Group Research Institute

Produced by: Science Popularization China

Produced by: China Science and Technology Press Co., Ltd., China Science and Technology Publishing House (Beijing) Digital Media Co., Ltd.