In 2020, some unusual and significant events happened in petroleum industry, meanwhile, there were also marking events taking place in the petroleum industry chain, which were completely unexpected in the petroleum industry and academic circle. These events include the negative WTI (West Texas Intermediate) oil price, price soaring of melt-blown nonwoven fabric, Exxon Mobil Corp. (NYSE:XOM) removed from Dow Jones Industrial Average, and the theory of oil demand peak revealed in the BP Energy Outlook 2020 Edition. How the prospectors are going to face and respond to these important events and how these events are going to impact hydrocarbon exploration have become an important subject that needs research and exploration.

In 2020, the spillover effect of the new type of Covid-19 pneumonia on the oil industry chain is huge, very shocking, affecting various aspects. Many events happened in the oil industry chain were unprecedented in history, which exerted a profound and wide impact on the oil exploration industry. We mainly analyze four of these events.

On April 20, 2020, the contract price of WTI crude oil futures of May fell sharply and closed at US $-37.63/bbl, which has never happened since the beginning of modern oil industry in 1859. In the past, oil prices had fallen to a few dollars or even cents, but negative oil prices had never been seen before, and it was thrilling (Fig. 1). China Petroleum News and other media also reported the event.

As a downstream product in the oil industry chain, the price of melt-blown nonwoven fabric skyrocketed when the oil price plummeted, and the gap has been extremely wide. The supply and demand of melt-blown nonwoven fabric has reached the point where “hard to get even one piece”. It is the most critical and core material for mask manufacturing, and it takes petroleum as the raw material. At the same time, the price trend of WTI and Brent crude oil deviated significantly from that of the melt-blown nonwoven fabric (Fig. 2). According to the statistics of material and equipment department of Daqing Oilfield, the average price of melt-blown nonwoven fabric, only tens of thousands of yuan per ton in the past, reached 52.5×10⁴ Yuan per ton in May 2020, and the highest price would exceed 60×10⁴ Yuan per ton, which is a small probability event.

On August 24, 2020, the world-famous Standard & Poor's Dow Jones company announced that it would make a major adjustment to the Dow Jones industrial average. An unknown company Salesforce replaced ExxonMobil. China’s first finance and Economics Network reported the incident with the sobering title of “ExxonMobil Sang the Elegy of Energy Stocks”. ExxonMobil had been the listed company with the highest market value in the world since it was included in the Dow Jones index in 1928. It was once an indisputable benchmark in the oil industry, yet it is out of the game now ^[1,2].

“BP World Energy Outlook (2020 Edition)” was released on September 14, 2020. As for the petroleum peak value, it used to refer to peak oil production, but in this report, it means peak oil consumption. According to this report, the oil consumption is mainly reflected in three aspects: first, in the net zero scenario, the oil demand will drop by 80% by 2050; second, in the net zero scenario, the proportion of oil in transportation energy consumption is expected to drop from 90% in 2018 to 20% in 2050; third, in the next 30 years, the oil demand will show a downward trend, and 2019 may be the peak of oil demand in human history (Figs. 3-5)^[3].

In the past, although many changes had happened in the oil industry, it was generally stable despite the ups and downs. But the recent big events have brought unexpected impact. The first big event is the change of oil price. In 2020, negative oil price emerged. The whole price system was broken down, literally. The second big event is the reverse mutation of some unexpected things, such as the skyrocketed rise of the price of melt-blown unwoven fabric. The third is that the benchmark of the world’s oil industry has fallen. More importantly, more than 80% of energy companies have been eliminated by the Dow Jones index. These events should be the major landmark events, but they are not absolutely so, instead, there are still uncertainties.

The above major landmark events have undoubtedly exerted a far-reaching impact on the oil industry, especially on the upstream areas of the oil industry. Oil and gas exploration is one of the sectors most intensive in theory and technology. It is also one of the areas with the greatest investment risk and the most effected by oil price fluctuations. At present and even in the future, for a long period of time, how to explore unknown areas in oil and gas exploration practice through theoretical and technological innovation facing many challenges will be a major proposition worth of consideration of oil and gas exploration professionals.

Based on analysis of the development of the world’s petroleum industry, this paper analyzes the major discovery cases in new areas of oil and gas exploration in China in recent years, including Gulong shale oil in Daqing Oilfield, so as to reveal the development sequence, prospect, logical relationship of oil and gas resources and corresponding technical countermeasures, and try to inspire oil prospectors in low-cost, high-quality and high-efficiency oil exploration.

In the whole petroleum industry chain, exploration is at the front, leading the whole chain. On the other hand, as an important participant in oil exploration, prospectors can significantly impact the development of petroleum industry in a special way. The responsibility of prospectors is to find oil.

Oil is buried underground, not easily seen or touched. Exploration is a process of constantly exploring the unknown and turning the unknown into the known. In order to find oil, should we have correct thinking methods, and scientific and technological means. These two aspects are indispensable, and more importantly, we should have a place to find oil. Wallace E. Platt (1885-1981) wrote an article “Toward a Philosophy of Oil-Finding” to address this concern. Wallace is a great master. His article is regarded as the benchmark and guidelines for oil exploration practice. This article was published twice in AAPG Bulletin: the first time was in the 12th issue of 1952; 30 years later, it was published again in the 9th issue of 1982, on the first anniversary of Mr. Wallace’s decease^[4,5]. In 1984, this article was introduced to China and published in the first issue of “Foreign Oil and Gas Exploration”^[6]. The first sentence of the last paragraph of this article is “To sum up, the first place to find oil is on people’s minds ^[6]”. So people say that oil is in the minds of geologists, and this idea has been accepted by many oil exploration professionals. A careful analysis shows that Wallace’s philosophy of oil finding mainly points out the dialectical and logical relationship between human brain and oil, emphasizing on the decisive and dynamic role of human brain.

There are two sentences in Hegel’s book Shorter Logic published in 1817: one is that “The nature of thinking itself is dialectics”, the other is that “Dialectics is the driving principle of all movements, all lives and all undertakings in the real world ^[7]”. The two sayings are consistent with the philosophy of oil finding. We can draw a preliminary conclusion that Wallace's philosophy of oil finding is Hegelian philosophy, emphasizing the importance of human beings; but at the same time, it confuses the dialectical relationship between initiative and decisive, and overemphasizes the logical relationship of the activities of the main body. In the future development, the things and situations will be more complex. With more advanced means, we need to learn from the history and in the light of development.

The development process of oil and gas finding cognition is summarized as the following: first, oil is an objective existence; secondly, oil is in people’s mind, which basically reflects Wallace’s point of view; thirdly, advancing forward, which reflects the role of science and technology and means; fourthly, until now, the development is attributed to the interactive collaboration of people hand in hand and mind on mind. This process can be summed up in two sentences: first, the relationship between the objective structure and the main body activity should be made clear in oil prospecting. There is a dialectical relationship of both internal tension and complementary between the two. Objective structure refers to the composition of future oil, not only of conventional or unconventional, but of many other types of oil resources; the main body activity refers to human imagination, including mental activity. The second is to clarify the logical relationship between initiative and determination, which is a dual logic of activism logic aiming to change the world and determinism logic based on science and technology^[8,9,10].

Let us take Gulong shale oil in Songliao Basin for example. Recently, a strategic and turning breakthrough has been achieved in Gulong shale oil. The first well of Gulong shale oil was drilled in 1981. Coincidentally, the well C.W.Slag^#1, the discovery well of shale gas, drilled by Michelle, the father of shale gas in the United States, was drilled in the same year. Then, in the early 1980s and late 1990s, we organized the research on the Cretaceous Qingshankou Formation in Songliao Basin, but no breakthrough has been made. It was only in 2020 that a strategic breakthrough was made ^[11].

One of the most important factors that contribute to the breakthrough of shale oil is the discovery of the “death line” of montmorillonite, which reverses the understanding of the side effects of clay minerals. In the past, it was thought that the higher the clay content, the lower the reservoir quality evaluation. But in fact, there are differences between clay minerals. For example, the “death line” of montmorillonite in Nenjiang Formation and Qingshankou formation is different. The former is 1200 m (Fig. 6a), while the latter is 800 m (Fig. 6b). The above discovery was achieved because prospectors had a new tool, the scanning electron microscope and the corresponding technical methods.

The more important significance of this discovery is that it has changed the vision of prospectors. From the perspective of discipline, sedimentary petrology is more deeply related to clay mineralogy. For sandstone, as a reservoir, people pay more attention to “production” and “storage”. While for shale, we should pay attention to “production” and “storage”, and pay attention to “generation”. This is a process of improving understanding, but more importantly, we must have technical means.

The element surface scanning map obtained by scanning electron microscope (SEM)/energy dispersive spectrometer (EDS) analysis technology can accurately identify the elements of various minerals in shale, and can be used to observe the composition characteristics of shale minerals with different depth and evolution degree. The vitrinite reflectance R_o of shale at different burial depths of Qingshankou Formation is 0.45%, 0.76% and 1.61% respectively (Fig. 7). With the increase of evolution degree, the mineral composition changes greatly. The biggest change is the disappearance of montmorillonite and the increase of illite, accompanied by a series of changes such as the increase of authigenic quartz, albite, ankerite, pyrite and calcite. Through new technological means, we have discovered phenomena that could not have been seen 20 or 30 years ago.

For sedimentary research, we need to pay attention to modern sediments and diagenetic rocks, and to the source of sediments. The organic matter wrapped in clay was originally thought to be aquatic. Now, the situation has changed a lot. Other than the self-generated organic matter in water, some are aeolian, which is brought by air, and some are brought by river. Some traces were found in the Gulong shale, which were deposited and slowly evolved. This process can be generally expressed as: silica, potash feldspar, montmorillonite, including carbonate and water, through a series of complex processes such as reduction, dehydration, dissolution, crystallization and hydrocarbon generation, finally formed illite, as well as albite, calcium carbonate, pyrite and ferrodolomite. During this process, a series of changes have taken place.

With the development of electron microscopy and other new technologies, we have not only learned about the changes of minerals, but also the microstructure, including the nanoscale microstructure. In the past, when we observed the core manually, we looked at the centimeter level and millimeter level profile, but now we can see a series of changes at the nanometer level. It can be seen that we can't do without means (Fig. 8). Therefore, it can be seen that human brain alone is in the role of initiative agency, while technology plays a decisive role. Decisiveness and initiative are dual logic, not a single logic.

In the past, Gulong shale could not produce oil. The final breakthrough and final production was the result of a series of changes in the rock through artificial transformation. Experiments show that the fractures of tight sandstone develop along the direction of maximum principal stress after fracturing, and are basically vertical (Fig. 9). However, after shale fracturing, there are very complex fractures, which cannot be explained by rock mechanics alone (Fig. 10). It should be noted that the experiment in Fig. 10 tracer was added, where the fracture development was shown to be different from the real core. Tracer is fluid, possessing the property of hydrodynamics.

The current research object requires us to integrate knowledge of multi-disciplines. The sandstone studied in the past was basically homogeneous, which changes according to the triaxial stress of rock mechanics. At present, the layered model is used to study shale, which is layer by layer. In a 1 m thick rock layer, there may be 3000 foliations, and even more abundant under the microscope. Therefore, with the updating of research means and methods, great and profound changes will take place in geological understanding (Fig. 11).

We should pay attention to the resources. From the perspective of oil and gas resources, Wallace’s oil finding philosophy is based on conventional oil and gas exploration. Now we have found tight oil and gas, and we have also produced oil in mature shale. In fact, the triangular future resources still has a large base, including immature shale oil and gas, organic matter, biomass, hydrocarbons, and inorganic hydrocarbons in nature (Fig. 12). Therefore, if we return oil to hydrocarbons in nature, resources are abundant. The content of hydrocarbon in nature is extremely high. We should know that resources exist objectively, and we must get to know them step by step. For the future, we need to be guided by a scientific epistemology^[12].

We should look at the value. The so-called value means that resources can really be turned into economic commodities. Now conventional resources and some unconventional resources have become economic commodities. Immature shale oil and gas, biomass and hydrocarbon resources cannot be seen as economic resources (Fig. 13). There are a positive triangle and an inverted triangle. The higher the top is, the better the quality of the resources and the greater the value. The lower the resource is, the less is its value reflected. The prospectors should explore the unknown fields from top to bottom. More importantly, the peak output theory was replaced by the peak demand theory. Why was it replaced? The main reason is that the comprehensive competitiveness of economy and ecology is not enough. If the competitiveness is strong enough, it cannot be replaced. It may go to replace other energy sources.

We should look at the trend. As is known to all, the classic oil and gas resources prediction curve, namely the Hubbert curve, is a bell shaped curve. Harbert is a well-known geologist who has accurately predicted the trend of oil production in the United States in the past 100 years. This trend is a bell shaped curve, that begins to decline after the peak (Fig. 14)^[13,14]. However, the exploration and development of the Permian Basin in the United States betrayed this curve. Its oil production peaked at 1.65×10 ⁸ t in the 1960s and 1970s, then dropped to 0.42×10 ⁸ t at the end of the last century, and rose to 1.86×10 ⁸ t in 2019 (Fig. 15). The reason is that the original curve was predicted according to the conventional way in a closed environment, without taking into account that in the production and demand of oil, there are both predictable factors and unpredictable factors. It is the future development formed by a joint drive.

So what is the future oil production like? In the future, oil and gas production may not be one peak or two peaks. If the two triangles mentioned above are fully coupled, they may be “wavy”. This line is the scientific trend of future oil development (Fig. 16). With the continuous progress of theory and technology, the oil and gas industry is constantly advancing in waves, not in the way that the peak will pass forever after it is reached.

The prospect of oil and gas resources lies in the exploration and understanding of the unknown. There are two books that explain the classical ideas and views on the unknown areas of nature. The first is The 4% Universe, written by Richard Panek. Panek believes that in nature, what we can recognize and see is only 4% of the whole universe, and more than 95% of universe is dark matter and dark energy, which we generally can’t feel^[16]. On the cosmic time scale, the time of human existence is very short. Even though the human cognition is constantly improving, it is far from reaching the level of fully understanding the objective world. With the continuous improvement of human cognition and the increase of technological means, we still have a lot to do. The second book is Petroleum^[17], published for more than 90 years. The author is Prof. Xie Jiarong (C.Y. Hsieh), a Chinese geologist. Xie Jiarong, a member of Academia Sinica in 1948, was one of the discoverers of Daqing Oilfield. The book he wrote at that time was actually a book of popular science. In the chapter titled “substitutes for oil” on page 150 of the book, he pointed out that there were two things that might replace the oil found at that time in the future. One is what we call oil shale. There is another thing, “the oil saturated shale”, that is, the so-called shale oil ^[17]. Our predecessors predicted 90 years ago that shale oil would become a substitute in the future. These two books reflect the same idea, that can be traced in both historical documents and unearthed cultural relics. In The Book of Rites • The Doctrine of The Mean, it is said: “the way of a gentleman is like this: he who goes far must be from near, and he who goes high must be from the foot.” ^[18] Recently, archaeologists have also found in Chu Bamboo Slips: Manifold of All Things sentence “climbing high from base, travel far from nigh^[19]” Base is low, nigh is near. It reflects the traditional thoughts of the Chinese nation.

If we combine this idea with the “wavy” curve, it is the way to go in the future. From conventional to unconventional resources, we will constantly change and discover their economic benefits and value. From mature reserves and immature shale resources, we will constantly discover new oil and gas to realize our future development. The vision of the petroleum industry development depends on the future scientific and technological innovation. The sustainable development of the petroleum industry will be realized by exploring unconventional and even unknown resources with low cost, high quality and high efficiency. Looking back at the development of human history, ships were one of the earliest means of transportation, which was powered by wind. It was the most primitive. Now we call it wind energy. The first car in the world, invented in 1839 by the Scots, was powered by electricity. In 1886, nearly 50 years later, the automobile with internal combustion engine was invented. In 1912, electric vehicles accounted for 40% of the European market, fuel vehicles accounted for 22%, and steam driven vehicles accounted for 37%. At that time, there were more electric cars than there are now. Why were they replaced by gasoline? Because the price of gasoline is lower, gasoline is more competitive. Therefore, future prospectors must combine these two maps (Figs. 12 and 13) and keep on going forward. Our prospectors should have wisdom, ability and methods to find more, cleaner and more affordable oil to drive the continuous progress of human civilization. This is the responsibility of oil prospectors.

Under the impact of both the novel coronavirus pneumonia (COVID-19 pandemic) and the sharp drop of international oil prices in 2020, the oil industry was faced with severe challenges. The oil exploration sector with the highest risk at the front of the industry chain encountered unprecedented impact. There are controversy views on the future of oil and gas exploration. In our opinion, the traditional petroleum exploration philosophy needs to be developed in succession, and the one-way logical thinking mode is difficult to make accurate judgment in the face of major events, while the double logical thinking mode can provide effective solutions. In the objective world, there are still many unexplored oil and gas fields to be discovered. Oil prospectors should not be limited to the inherent understanding, but should introduce high and new technology, innovate the theory and technology of oil and gas exploration and development, actively explore the blind area of understanding in the field of natural oil and gas energy, and convert the difficult to produce reserves into technologically recoverable and even economically recoverable reserves. In addition, they should intensify scientific and technological research and development and gradually expand the scope of known resources and narrow the boundary of unknown resources. All in all, although the challenges of the petroleum industry continue to exist, the prospect of oil and gas resources is broad, and the opportunities for major oil and gas discoveries lie in the exploration and understanding of unknown fields. As long as oil explorers adhere to scientific and technological innovation, the future development vision of the petroleum industry is optimistic. As long as we focus on low-cost, high-quality, high-efficiency exploration and exploration of unconventional and even unknown resources, the sustainable development of petroleum industry is bound to be realized.