On August 25, exciting news came from the press conference held by PetroChina Daqing Oilfield: Daqing Oilfield Gulong shale oil exploration has made a major strategic breakthrough, with an exploration area of 14,600 square kilometers, and the oil-bearing area will be confirmed in 2021. 1413 square kilometers, the newly-added predicted oil reserves of 1.268 billion tons, which is equivalent to finding another “new Daqing” under Daqing.
What is the significance of this major strategic breakthrough in shale oil exploration in Daqing Oilfield? What are the far-reaching effects on the development of other domestic oil fields and my country’s energy security? This reporter interviewed relevant experts.
Theoretical breakthrough——
Achieve from the “generation” of oil from continental shale to the “production” of oil from continental shale
In Yaoxin Township, Durbert Mongolian Autonomous County, which is more than two hours away from the city of Daqing, the Guyeyouping 1 Well of Daqing Oilfield stands tall. It has been discharged for 500 consecutive days since the oil was seen on February 21, 2020. , The cumulative production of crude oil is 6,000 tons, and the cumulative production of oil and gas equivalent is nearly 10,000 tons. The output of a single well is 10 times the average output of a single well in the Daqing Oilfield. “This fully proves that continental shale can not only generate oil, but also can produce oil. The output is not only considerable, but also stable.” said Lin Xudong, head of the research and deployment team of the front-line command of the Daqing Oilfield Shale Oil Exploration and Development Conference.
Many people are no strangers to shale oil. The United States has achieved energy independence by relying on the shale oil and gas revolution. Unlike the marine shale oil that has been successfully developed abroad, my country’s shale oil is mainly continental shale oil. Western geologists once asserted: “Marine shale can generate oil, but continental shale cannot.” In fact, most of the oil resources discovered in the world are in marine strata, so the potential of continental strata is not optimistic. .
As early as the 1980s, Daqing Oilfield had conducted research and exploration of shale oil, but due to theoretical understanding and technical limitations, the oil output of a single well was limited, and high production and sustained stable production have not been achieved.
Daqing Oilfield also invited major international companies such as Shell and BP to carry out preliminary evaluation studies on Gulong shale oil. The answer they gave was: No similar shale oil with commercial development value has been discovered globally, and the risk of exploration and development is very high. .
“Previous geological theories believed that shale layers only generate oil, and as the migrated oil flows to other places, conventional exploitable oil layers are formed, while shale itself contains very little oil. In layman’s terms, there is not much oil in mudstone. Even if it is produced, it will not be able to produce high and stable production, let alone profitable development.” explained Zhang Jinyou, manager of the shale oil project department of the Daqing Oilfield Exploration and Development Research Institute. Therefore, shale oil has not been lost for a long time. Listed as an object of exploration and mining.
As an old oilfield with more than 60 years of exploration and development, Daqing Oilfield has faced severe challenges in recent years from imbalances in storage and production and difficulties in stabilizing production. “The proven rate of Daqing conventional oil resources has reached 62.7%. The oilfield development has entered the later stage, and the recoverable reserves have been declining. As the benchmark and banner of the national industrial front, Daqing Oilfield must bravely shoulder heavy responsibilities and seek new breakthroughs.” Said Zhu Guowen, vice president of the company limited by shares, secretary of the party committee of Daqing Oilfield, and executive director of Daqing Oilfield Co., Ltd.
As for the exploration of shale oil, people in Daqing Oilfield have never given up. In 2018, oilfield researchers analyzed and studied the cores extracted from the Gulong area 50 years ago, and put forward a bold theoretical idea: part of the oil generated in the shale migrates to oil layers such as Saertu to form the conventional oil of the Daqing Placanticline. , There should be a lot of shale stuck in the oil-generating shale. “The shale oil collected by other homes has been migrated and has been hidden in the’married daughter’ in the mineable rock layers of sandstone or carbonate rock sandwiched by shale. We are born as’big fat boys’. At home.” He Wenyuan, deputy general manager, chief geologist, and commander-in-chief of the shale oil exploration and development headquarters of Daqing Oilfield, likened it vividly, “We need to find and extract this part of the oil that stays in the shale.”
In 2018, Daqing Oilfield marched towards the shale oil of the Qingshankou Formation in the source, drilling the ancient page oil Ping 1 well for test production, which was successful. Well Guyeyouping 1 uses high-yield industrial oil and gas with a daily oil output of 30.5 tons and a daily gas output of 13,000 cubic meters, showing the broad resource prospects of continental shale oil.
“Gulong shale oil has broken the concepts and understandings of traditional petroleum exploration and development, and has realized the transition from continental shale oil generation to continental shale oil production; from classic petroleum geology migration and accumulation to high organic matter shale The leap of in-situ rock accumulation has enriched and developed the theory of petroleum geology.” He Wenyuan said.
Technological innovation——
Start a new battle
The successful test of Well Guyeyouping 1 greatly strengthened the confidence and determination of Daqing Oilfield people to develop shale oil. But then the question arises, how many reserves of Gulong shale oil? How much can be explored and mined? How to achieve economies of scale development?
In 2020, Daqing Oilfield opened up a pilot test for the development of the high gas-oil ratio area around the Guye Youping 1 well, which achieved a major breakthrough, and established the “Gulong Shale Oil No. 1 Test Area”, which kicked off an exploration and development of Gulong shale oil. New battle. “Different from the oil congress in the 1960s, the new controversy is a scientific and technological battle under the guidance of new development concepts, focusing on understanding the unknown and tackling key tests.” For the new controversy, Daqing Oilfield General Manager Fang Qing interpreted this way.
Different from the interbedded and mixed shale oil that has been developed at home and abroad, Daqing shale oil is mud-grade shale with smaller pores and higher density, and the engineering technology is extremely difficult.
At the beginning of the battle, the first well was unsuccessful because of the instability of the well wall and spalling. The company’s chief technical expert and deputy commander of the Daqing Shale Oil Command, Yang Zhiguang, and the members of the working group worked endlessly for days and nights, repeatedly studying countermeasures, and finally found a way to increase the mud density and enhance the plugging performance.
In order to produce oil, the formation must be cracked by pressure. Therefore, fracturing technology is referred to as a “hands-on” in oil field exploitation, and it is very important. As a fracturing expert, Zhang Yongping, the chief technical expert of the Daqing Oil Production Engineering Research Institute, has more than 30 years of work experience, but this time he still encountered a big problem. “Conventional oil is similar to an oil bag. Oil production is done by building a high-speed channel underground, allowing the oil to flow down the channel to the bottom of the well, and then pump it up. Shale oil is distributed on many tiny pores, the size of which is equivalent to one size. 1/500th of the hair strands, and the pores are closed, the plane flow is poor, the longitudinal flow does not flow, and the fracturing is very difficult.” After many scientific researches, he led the technical team to explore the “inverse mixing, flow-limiting jet” The main process of fracturing with holes and compound production.
From shale oil drilling plan design to fracturing fluid and other key raw materials and tools research and development, from oil production engineering research to production stimulation and transformation technology research, facing the “new continent” of shale oil development, scientific researchers continue to make technological breakthroughs.
“At present, supporting excellent and fast horizontal well drilling technology and composite fracturing technology have become the core technology system supporting the exploration and development of Gulong shale oil, and a major breakthrough in key engineering technology. In addition, geophysical identification and prediction technology, enrichment layer and enrichment The comprehensive evaluation technology of the cluster is also internationally leading. At the same time, in the process of ground construction, innovation is being carried out in accordance with the idea of’multi-energy complementation, full sealing, quality treatment, and cleaner production’ to establish a green and low-carbon with Daqing characteristics. Production technology.” He Wenyuan said.
Abundant reserves-
Brings new changes in oil exploration thinking
According to reports, Daqing Gulong shale oil favorable area covers an area of 14,600 square kilometers, which is more than five times that of Daqing’s main oil field. “Through unremitting efforts, we have finally realized the dream of’finding Daqing under Daqing’, which is expected to fundamentally improve the overall imbalance of storage and production of old oilfields in the post-reservoir development stage and the contradiction of insufficient production capacity replacement, and enhance the stamina for sustained and stable production. Confidence and strength to ensure national energy security.” Fang Qing said.
One of the discoverers of the Daqing Oilfield, Qiu Zhongjian, academician of the Chinese Academy of Engineering, and Zou Caoeng Significant discovery. This is an industrial and scientific discovery. There are such big discoveries at present. They send charcoal in the snow, rain in time, and are a strategic resource.”
“Gulong shale oil is not only high-yield but also of good quality. One ton of oil can’pull out’ 27% of light hydrocarbons. There is also a large amount of ethane in natural gas, which is of higher value. Calculated at an oil price of US$45 per barrel, per ton of oil It is worth 490 yuan more than Daqing’s crude oil. If some suitable surface technology is used to form an integrated upstream and downstream ethylene industry chain, the value will be even greater.” Zhang Jinyou said.
Zhu Guowen specifically explained the significance of Daqing Gulong shale oil exploration and development from the five aspects of science, economy, industry, society and demonstration: It will get rid of the imbalance of storage and production in old oilfields and realize the growth of total oil and gas scale; it will drive the leaping development of Daqing’s upstream and downstream integrated ethylene industry chain value chain; it will help Daqing to become the leader in the transformation and upgrading of resource-based cities in the country ; It will promote the continental shale oil and gas revolution in my country and affect the development of global shale oil and gas.”
The breakthrough in the exploration of Gulong shale oil in Daqing Oilfield has brought new changes in exploration thinking, demonstrated the huge development space and potential of my country’s continental shale oil, and has demonstration and guiding significance for the development of similar resources in China. But at the same time, many experts also said that as a type of unconventional resource, exploration and development of continental shale oil still faces challenges in theory, technology, cost, and efficiency. It is necessary to further strengthen scientific and technological research and management innovation to achieve scale. Effective development.
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