Cao Xiaopeng, chief geologist at Sinopec's Shengli Oilfield Exploration and Development Research Institute's CCUS (Carbon Dioxide Capture, Utilization and Storage) Key Laboratory in Dongying, the central city of the Yellow River Delta, is carefully analyzing more than 30 small stones.
"These are no ordinary stones. Cao Xiaopeng told the reporter of Science and Technology Daily who was present, "They have a lot of origins, and they are all cores extracted from the environment of 3,000 meters underground and 120 °C." ”
Using these cores, researchers in Shengli Oilfield simulated the underground environment and carried out carbon dioxide flooding and storage experiments. From basic research to applied research to engineering practice, four generations of scientific researchers have worked hard for 55 years to finally achieve China's first megaton CCUS.
Seal the carbon in the ground and drive the oil out
Under the "dual carbon" goal, reducing carbon dioxide emissions is a top priority. In the eyes of the researchers in the Shengli Oilfield, carbon dioxide is the treasure of increasing oil production.
The traditional practice of extracting oil fields is to inject water into the ground to drive the oil up. However, with the longer development time, the oil in the ground becomes less and less, and the water cut of some reservoirs increases, resulting in a decrease in the efficiency of water flooding and an increase in the cost of oil recovery.
The idea of replacing water with carbon dioxide has been brewing since the 20th century. However, at that time, the idea of "sealing the carbon underground and driving the oil out" was too difficult to land, and it belonged to the "no man's land" of scientific research.
In 1967, at the Shengli Oilfield Exploration and Development Research Institute (hereinafter referred to as the Institute), 27-year-old Cao Yinsheng devoted himself to the research of carbon dioxide flooding without hesitation with the steadfastness, passion and tenacity of an oil man. He and his colleagues built a gas flooding laboratory brick by brick, solved a number of theoretical problems such as the physical properties, pressure and temperature of crude oil that affect the efficiency of carbon dioxide flooding, became the first generation of "oil flooders" in this field, and laid the foundation for carbon dioxide flooding research.
Shengli oilfield scientists are analyzing shale cores. Courtesy of Shengli Oilfield
Along the scientific research chain of "making progress in basic research, driving applied research innovation, and achieving breakthroughs in core technologies", a relay race continues to be carried out in the institute. In the 21st century, the second generation of "oil displacement" represented by Zhang Chuanbao took over the baton.
Zhang's team conducted a pilot test on near-miscible flooding using carbon dioxide, which proved to be effective, but the effect was not satisfactory because the underground pressure was insufficient, resulting in the failure of carbon dioxide to liquefy. As a result, they suggested that blending carbon dioxide with crude oil could be the key to improving the effectiveness of oil displacement.
But the question then arises: how much pressure does it take for oil and gas to form miscibles underground?
"Continue to simmer! Less than 40 megapascals, resolutely do not open the well!"
In the Fan 142 block of a similar reservoir in the Shengli Oilfield, researchers focused on an injection well that ran from 2013 to 2016, from 17 megapascals to 40 megapascals......
"Open the well!" "It's done!"
When the black liquid sprayed out and sprinkled into the sky, the second generation of "oil dispersants" cried with joy.
Break through the technical blockages and practice "unique skills"
At present, the mainland CCUS is in the stage of industrialization demonstration, and some key technologies are still far behind the international advanced level. "Ensuring energy security is a task entrusted by the state, and it is our bounden duty to tackle key problems in core technologies!" Zhao Tiejun, deputy manager of the carbon dioxide project department of Sinopec Shengli Oilfield Steam Injection Technology Service Center, has a full sense of mission.
Shengli Oilfield Lai 113 carbon dioxide injection site. Courtesy of Shengli Oilfield
In 2010, as soon as Zhao Tiejun graduated, he plunged headlong into the high 89-1 block, which was undergoing carbon dioxide pilot testing.
At this time, carbon dioxide flooding has been verified, but how to inject carbon dioxide into the ground safely and efficiently is a headache.
If you want to "fight the tiger" to pass the level, you must first have equipment. The high-pressure precision flow meter is the "eye" of the CO2 injection equipment. With it, it is possible to inject multiple wells at the same time with one pump. Zhao Tiejun has referred to foreign measurement technology routes, but has not been able to break through the bottleneck of ultra-high pressure accurate mass measurement.
In half a year, Zhao Tiejun and his colleagues measured tens of thousands of sets of data on site, and after thousands of repeated trials, the team finally extended the carbon dioxide density plate that was up to 25 megapascals in use in the world at that time to 40 megapascals, and then integrated the density plate into the general volumetric flow meter to achieve accurate mass measurement of carbon dioxide in the liquid state.
On the basis of breaking through the metering technology, the third-generation "oil displacement" has innovated and developed low-temperature high-efficiency closed injection equipment, formed a key technical system with completely independent property rights, solved a series of high-challenge problems such as zero emission of carbon dioxide injection, partial pressure and injection, and low-temperature metering, and opened up the technical blockages of the CCUS industry chain, which is known as a "unique stunt" by the outside world.
The field practice data of Shengli Oilfield shows that the carbon dioxide flooding efficiency is 40% higher than that of water flooding, and the storage rate can reach 60%-70% at a time, and finally reach 100%.
It is not only a problem solver, but also an application leader
On the road to building the source of original technology, Shengli Oilfield plays multiple roles such as problem solver, tackler, applicator and leader at the same time, but it is difficult to play each role well.
The injection problem has been solved, and a new problem has come: "anti-channeling". To put it simply, it's how to keep CO2 "honestly" underground.
From 10 minutes to 30 minutes to 60 minutes, the maintenance time of carbon dioxide foam has been continuously refreshed in ten years, and the storage rate has exceeded 70% at one time. With the continuous improvement of "anti-channeling" technology, Shengli Oilfield has initially formed six major technology series of the whole CCUS industry chain, such as low-cost capture technology and pipeline safe transportation technology.
Shale Oil Laboratory of Shengli Oilfield Research Institute of Exploration and Development. Courtesy of Shengli Oilfield
In 2020, the "baton" was passed to the hands of Zheng Wenkuan, the fourth-generation "oil displacement". He and his colleagues are tackling the challenge of recreating the flow of fluid in underground reservoirs and developing more scientific development plans to produce more oil. Shengli Oilfield is also accelerating the expansion of the application field of carbon dioxide flooding and storage technology, and gradually expanding the scale of oil displacement and storage.
The "Qilu Petrochemical-Shengli Oilfield Million-ton CCUS Project" has been put into operation, which is expected to increase oil by nearly 3 million tons by 2025 and reduce carbon dioxide emissions by 1 million tons per year, equivalent to planting nearly 9 million trees.
From conception to practice, the four generations of "oil displacement" in Shengli Oilfield have mastered key theoretical technologies from carbon dioxide capture, miscible flooding to storage, and explored a unique CCUS road.
The report of the 20th National Congress of the Communist Party of China proposed to increase the exploration and development of oil and gas resources, increase reserves and production, and accelerate the planning and construction of a new energy system. "The development of CCUS is to create a new way for the industrialization of oil and carbon sequestration, promote regional economic and social development and the ecological protection of the Yellow River Basin, and shoulder the responsibility of a central enterprise for the green and low-carbon development of ecological civilization!"
Source: Science and Technology Daily