China solves three world problems of shale oil production.
Distribution map of conventional and unconventional oil and gas accumulation types
reveal a secret
In 2023 Zhongguancun Forum, China continental shale oil revolution and strategic breakthrough were officially released. The results have innovated China’s geological theory of continental shale oil enrichment, and solved the world scientific problems of "oil generation", "oil storage" and "oil production" of continental shale; The key technical system of continental shale oil in China was established. A number of independent intellectual property rights have been formed; National demonstration areas and bases have been built in Longdong of Ordos Basin, Jimsar of Junggar Basin and Gulong of Songliao Basin.
Squeeze oil from shale
It is reported that the continental shale in China has triggered two "oil revolutions". The first time was "continental shale oil generation", and a number of large oil fields such as Daqing were discovered, which broke the "China’s theory of poor oil" and supported the development of China’s conventional oil industry, comparable to "two bombs and one satellite"; The second time was "Oil Production from Continental Shale", and the target of work was to move from "monomer" conventional oil, which accounted for 20% of the resources, to "continuous" unconventional oil, which opened a new round of "oil revolution" and is expected to support the future development of China’s unconventional oil industry.
In the past, it was generally believed that shale, like "grindstone" and "iron plate", generally had no pores and could only be used as the cover of conventional reservoirs. In fact, it contains huge oil resources in a larger area.
The so-called shale refers to the shale with sheet shape in the oil-gas bearing basin. When it is rich in organic matter, it is also called source rock, which is often called source rock. Different from the direct development of conventional reservoirs by natural energy and conventional means, shale oil needs to be developed by artificial means by unconventional means. For example, if coconut juice is compared to conventional oil, the juice squeezed from coconut meat is unconventional oil, and shale oil is "squeezed" from shale.
China’s shale oil is mainly distributed in large basins such as Ordos, Songliao, Junggar, Bohai Bay and Sichuan, as well as many "small but fat" small and medium-sized basins. The continuous distribution area is small, the maturity is low, the clay content is high, and the oil quality is heavy. At the same time, China’s shale oil exploration and development started late, the research degree is low, the drilling and fracturing cycle is long, and the construction cost is high. Medium and high mature shale oil resources are generally buried in the central and western basins. At present, the buried depth of the largest shale oil layer has reached 5000 meters, so it is difficult to implement drilling, completion, fracturing and other projects, with large investment and high risks.
Last year, the output exceeded 3 million tons
Professor Yang Zhi, deputy director of tight oil Research Institute of China Petroleum Exploration and Development Research Institute and executive director of China Petroleum’s "14th Five-Year Plan" shale oil forward-looking basic major science and technology project, told the Beijing Youth Daily reporter that the pore size of rocks stored in conventional oil reservoirs is relatively large, and the scale can reach millimeter-scale centimeter-scale, but now continental shale oil is equivalent to finding oil from shale particles with hair-scale of about 70 microns, and the pore size is micron-scale and nano-scale, which makes exploration and development extremely difficult.
From the perspective of exploration, it is very accurate to find a few meters or more of thin rich layers in the depth range of several kilometers underground. After very difficult exploration, the favorable reservoir drilling rate can reach more than 90% at present. From the development point of view, it is generally to drill a straight well. Under the condition of natural energy, oil can flow to the ground by itself through the wellbore, but shale oil has no natural flow conditions, so it needs human intervention to break up iron shale and create flow conditions.
Mining is difficult and costly. Why should shale oil be mined? In this regard, Professor Yang Zhi said that our country has been short of oil for some time, and every oil resource is very precious. Although we have achieved self-sufficiency in oil at present, in order to ensure oil safety, we still need to rely on science and technology to stand on our own feet and seek oil. Shale series petroleum is a strategic replacement petroleum resource, and its scale benefit development is of great strategic significance. In the past ten years, continental shale oil has grown from scratch, and in 2022, the output of continental shale oil in China oil mining area has exceeded 3 million tons.
Solve three world problems
Professor Yang Zhi said that in recent ten years, China Petroleum has experienced a series of major landmark events in the field of shale oil, such as nano-hole discovery, national 973 R&D, national laboratory construction, international cooperative research, exploration risk well deployment, development pilot test, national demonstration zone construction, etc., realizing the revolutionary innovation of "continental shale oil production" and forming a series of characteristic theories and technologies.
Professor Yang Zhi introduced that, on the one hand, he innovated China’s geological theory of continental shale oil enrichment, and solved three world scientific problems of "oil generation", "oil storage" and "oil production" of continental shale: creating a sedimentary model of continental shale rich in organic matter; The nano pore throat oil storage system of shale was discovered. The enrichment law of "continuous" dessert area and dessert section of shale oil is revealed.
On the other hand, four key technical systems, including experimental research, exploration and evaluation, development engineering and advanced innovation, have been established in China, and a number of independent intellectual property rights have been formed. Among them, the digital rock intelligent evaluation technology has realized the fusion of "9" orders of magnitude from meter to nanometer. At the same time, a series of shale oil development engineering technologies has been created, mainly including volume development and large platform — 8 core technologies such as well plant development. In addition, the in-situ transformation of medium and low mature shale oil was started, which basically solved the key technical problems such as resource evaluation and selection, and developed a number of achievements with independent intellectual property rights, including 3 national standards and 35 technical secrets.
Find the "golden key" to exploit oil from shale
Professor Yang Zhi further introduced that theoretical and technological innovation has led to three strategic breakthroughs in China’s continental shale oil. The first aspect: A number of major exploration discoveries have been made in Ordos, Junggar, Songliao, Bohai Bay, Sichuan and Qaidam basins. The second aspect: the national demonstration areas and bases in Longdong, Jimsar and Gulong have been built. The demonstration base of shale oil development in Ordos Basin in central China has built the largest shale oil field in China at present. Jimsar in western Junggar basin is the first national demonstration area of continental shale oil in China. The national demonstration zone of Gulong continental shale oil in eastern anniversary has made a major breakthrough with strategic significance. The third aspect: driven by innovation, continental shale oil has become a national strategic resource.
Not only that, after shale oil is mined, it is necessary to control the cost as much as possible under market conditions and form the development of scale benefits. According to public reports, the shale oil benefit development demonstration platform of China Petroleum Dagang Oilfield Company — — Platform 5 in Cangdong sag has been put into production. There are 9 shale oil wells in the platform, with a daily production capacity of about 280 tons, forming an annual production capacity of 100,000 tons. This marks that China’s first 100,000-ton shale oil benefit development demonstration platform was officially completed and put into operation in Dagang Oilfield. According to estimates, the four wells deployed in the early stage of the platform have a total daily oil production of more than 40 tons. The output of five newly deployed wells has been further improved, and the daily oil production of a single well is stable at 40 tons to 50 tons. It is predicted that the first annual oil production of a single well can exceed 10,000 tons, and the final recovery of a single well is expected to reach 41,000 tons, thus realizing the beneficial development of continental shale oil.
Professor Yang Zhi said that Cangdong Platform is one of the successful cases. Changqing Oilfield took the lead in building the first million-ton integrated oil zone in China in Loess Plateau, and its shale oil output ranked first in the country. Last year, its output exceeded 2 million tons. Xinjiang Oilfield is located in Jimsar Gobi, and the first national shale oil demonstration zone is being built in China. Last year, its output exceeded 500,000 tons. There is also Gulong shale oil in Daqing Oilfield, which is widely concerned. Relatively speaking, it is more difficult to develop. Last year, the output also exceeded 100,000 tons of oil equivalent.
It is not difficult to see that the theoretical and technological innovation and practice of continental shale oil in China have broken through the "theoretical misunderstanding", the "exploration forbidden zone", the "no man’s land for development" and found the "golden key" to exploit oil from shale, which is starting a new "oil revolution".
Text/reporter Song Xia
Photo courtesy/interviewee