The two major national-level mega-projects, "Haikui No. 1" and "Haiji No. 2," have been put into operation simultaneously, extending the production life of the Liuhua Oilfield by nearly 30 years. How do these national mega-projects awaken the deep-sea oil dragon and create this deep-sea "super engineering" project? Our reporter walked into the Liuhua Oilfield production site to reveal the secrets for you.

Xie Xiulong, Platform Director of CNOOC's Haiji No. 2: We are currently standing on the jacket of the "Haiji No. 2" platform. As Asia's first deepwater jacket platform, its jacket is 338.5 meters tall. In a sense, we are standing at the top of Asia.

"Haiji No. 2" is a large offshore production platform integrating drilling, production, and living functions, with a total weight exceeding 50,000 tons. It is Asia's tallest and heaviest offshore crude oil production platform. Xie Xiulong told reporters that to ensure the safe and stable operation of this giant structure, sensors with various functions are installed on the jacket to monitor in real time the stress conditions, movement, and corrosion of the jacket.

Xie Xiulong, Platform Director of CNOOC's Haiji No. 2: This is our platform's tensioned impressed current cathodic protection system. Through this device, current is impressed to protect the jacket itself, and its protective effect is transmitted back to our central control via sensors. There are more than 380 such sensors on our platform in total, enabling dynamic management of the platform. These monitoring data are also transmitted back to our onshore control center via satellite and microwave.

For offshore oil extraction, the biggest challenge compared with onshore operations is the seawater in between. It not only increases extraction costs but also brings more risks. The deeper the water, the more severe these challenges become. To overcome these difficulties, people have explored various methods, among which extraction via jacket platforms is one of the more economical and safe approaches.

Xie Xiulong, Platform Director of CNOOC's Haiji No. 2: Although we have only one derrick, in the future we will drill 24 wells in an area less than half a basketball court in size. This approach can greatly reduce the extraction costs of the entire oilfield.

The drill bit passes through 300 meters of seawater to drill 24 wells precisely and densely on the seabed, with a positional accuracy error of no more than 5 centimeters for each well. At the same time, it must overcome the disturbance of underwater internal wave currents and the challenges posed by the complex and variable seabed terrain. The operational difficulty is comparable to threading a needle from a hundred meters away.

Zhang Xin, Drilling Director of CNOOC's Haiji No. 2: By optimizing drilling parameters and bottomhole assemblies, we keep the wellbore straight and control the deviation to less than 0.5°. At the same time, we use underwater micro-robots to provide visual assistance for precise positioning and rapid movement of the drilling tools underwater, thus achieving efficient and precise drilling operations.

Zhang Xin showed reporters an underwater distribution map of the oil wells. The underwater wells do not go straight down but spread out like the roots of a large tree. Their total drilling footage exceeds 73,500 meters, equivalent to drilling through the height of eight Mount Everests.

Zhang Xin, Drilling Director of CNOOC's Haiji No. 2: The trajectories of the wells below are like a large tree, with roots spreading in all directions. The rotary steerable system we use is like giving the drill bit eyes, enabling precise control of the bit within thousands of meters underground. This is the secret of why we can achieve non-interference among 24 wells within such a small formation space.

The crude oil extracted from the seabed is pressurized by four crude oil export pumps on "Haiji No. 2" and transported 2.5 kilometers away to "Haikui No. 1" for further three-phase separation of oil, gas, and water. Qualified crude oil with a water content below 0.5% enters the cargo oil tanks, awaiting shuttle tanker offloading. Every day, "Haikui No. 1" can process more than 5,600 tons of crude oil, equivalent to filling the tanks of 900,000 cars, further providing a solid guarantee for China's energy supply.

　　Digital and intelligent technologies empower safety management of deepwater oilfields

In recent years, China has steadily advanced the construction of intelligent oilfields, achieving digital and intelligent transformation of offshore operations through the deep integration of digital technologies such as cloud computing, the Internet of Things, big data, and artificial intelligence with core exploration and development businesses. The application of digital and intelligent technologies on "Haikui No. 1" has also greatly improved the safety management efficiency of the deepwater oilfield.

"Haikui No. 1" is the world's first "digital and intelligent" cylindrical "offshore oil and gas processing plant" integrating multiple systems such as integrated ocean monitoring, health management of electromechanical and instrumentation equipment, and 3D visualization management. Equipped with these intelligent and digital systems, it can achieve real-time monitoring, dynamic management, and timely maintenance of various data throughout the facility's service life, which is of great significance for monitoring extreme environments, strengthening safety risk prevention, and enhancing the structural safety of deep-sea oil and gas equipment.

Jiang Junda, General Manager of the Liuhua Oilfield of CNOOC Shenzhen Branch: "Haikui No. 1" has applied an integrated ocean data analysis system for the first time. Going forward, we will further advance intelligent construction, continuously expand "digital" and "intelligent" application scenarios oriented to actual production needs, and accelerate the creation of new quality productive forces for deepwater oilfield development.

In addition, "Haiji No. 2" and "Haikui No. 1" have now successfully achieved 5G network communication coverage. The Liuhua Oilfield has become the oilfield group with the farthest offshore distance among units with built 5G networks in the eastern South China Sea. It can provide more stable communication guarantees for the operation of the typhoon production mode, facilitate the development of intelligent diagnosis of key equipment in the Liuhua Oilfield and the application of various digital and intelligent tools, and further promote the intelligent upgrading of deepwater oil and gas exploration and development.

　　Independent R&D of new equipment drives coordinated development of the domestic industrial chain

The technological innovation and rapid development of offshore oil and gas equipment have supported and driven breakthroughs in key core technologies and green transformation of China's equipment manufacturing industry.

"Haikui No. 1" and "Haiji No. 2" highly integrate more than 1,000 key pieces of equipment, about 90% of which are independently designed and manufactured by China.

Liu Huaxiang, General Manager of the Deepwater Engineering Construction Center of CNOOC Shenzhen Branch: We carried out targeted research on more than 10 sets of domestically produced equipment, including large-specification anchor chains, cargo oil pumps, monitoring and control equipment, and process treatment equipment, filling gaps in the domestic offshore engineering industry and driving the high-quality development of industries including steel, high-end new material R&D, and the manufacturing of major and high-end equipment.

The fully independent design and construction of "Haikui No. 1" plays a leading role in the entire industrial chain. At present, China has fully acquired the independent R&D capability for offshore oil and gas engineering equipment within a water depth of 3,000 meters, and the level of independent design and manufacturing of deepwater offshore oil and gas equipment is gradually entering the world's first tier.

　　China achieves breakthroughs in the design and construction capability of offshore oil and gas equipment

In the development of offshore oil and gas resources, equipment design and construction are key technical bottlenecks. After rapid development in recent years, China's design and construction capability for offshore oil and gas equipment has achieved important breakthroughs, moving from "following" and "running in parallel" to "leading."

On August 12, the Mazan oil and gas gathering and transportation platform, the largest international offshore oil and gas platform built by China, was completed and delivered. On August 22, the central processing platform of the Bozhong 19-2 Oilfield, part of the Bohai integrated, high-quality large oilfield "Five Stars in a Row" oil and gas production cluster, was installed. In the first half of this year, China completed the construction of more than 20 individual offshore oil and gas equipment units, setting a record high for workload in the same period.

Tao Fuwen, General Manager of COOEC Qingdao Company: Through our independent research, we have developed a set of standardized and serialized technical achievements for offshore oil and gas equipment that can be reused and built in batches. Important breakthroughs have been made in intelligent manufacturing technology, and technologies for various types of mainstream deepwater floating and semi-submersible production and storage equipment have achieved all-round improvements from basic theory and design to construction and installation.

Deep water is the main replacement area for global oil and gas resources in the future. In recent years, China has successively built a number of floating offshore facilities, including "Offshore Oil 119," the offshore oil and gas processing plant with the largest operating water depth in China, and the "Deep Sea No. 1" energy station, the world's first 100,000-ton-class semi-submersible production and storage platform. Continuous key breakthroughs have been made in the design and construction capability of deepwater and ultra-deepwater floating oil and gas equipment. Up to now, China has built more than 50 ten-thousand-ton-class fixed offshore platforms and has successfully mastered a complete set of independent design and construction technologies for 30,000-ton-class ultra-large offshore platforms and 300-meter-class deepwater fixed offshore platforms.