Opening up the "information artery" of offshore smart oil fields

Tech 2023-06-20 08:51:28 Source: Network

After seeing the expert group's opinion of "agreeing to pass the acceptance", Li Zhong, Deputy General Manager and Chief Engineer (drilling and completion) of CNOOC Research Institute, breathed a sigh of relief.The "Research on Key Technologies for Online Monitoring of Offshore Oil and Gas Wells" led by Li Zhong has recently passed acceptance, and the results have been highly recognized by the expert group

After seeing the expert group's opinion of "agreeing to pass the acceptance", Li Zhong, Deputy General Manager and Chief Engineer (drilling and completion) of CNOOC Research Institute, breathed a sigh of relief.

The "Research on Key Technologies for Online Monitoring of Offshore Oil and Gas Wells" led by Li Zhong has recently passed acceptance, and the results have been highly recognized by the expert group. The fierce battle of over 1000 days and nights has finally achieved phased results.

From scratch, Li Zhong's team systematically constructed a high-precision, high-density, and multi-dimensional integrated monitoring and control theoretical system for offshore oil wells, proposed independent integrated solutions for measurement, transmission, and control, and opened up the "information artery" of offshore smart oil fields.

Looking back on more than three years of tackling key problems, Li Zhong said in an interview with a reporter from Science and Technology Daily: "Innovation is the process of solving one problem after another, and constantly 'upgrading and attacking'."

Find a good way to "pulse" the oil well

Building a smart oil well is the long-cherished wish of Li Zhong, a veteran of offshore oil development who has been working on the front line for 27 years.

After arriving at CNOOC Research Institute, I thoroughly investigated the party building research and found that our team has a good foundation in digitization and intelligence. Therefore, I made up my mind to do this, "Li Zhong recalled.

This is indeed a must do thing.

Nowadays, there are fewer and fewer "desserts" in oil and gas development, and the remaining ones are mostly "residues". How to do everything possible to improve quality and efficiency, achieve refined management, and try to eat these "residues" as clean as possible is a topic that oil and gas developers are facing.

For a country like us with poor oil resources, this is even more so, "said Li Zhong.

The beginning of everything is difficult.

The foundation of intelligence is data. The construction of offshore smart oil fields requires rich underground monitoring data as support. The development of technology for obtaining underground data has become the first challenge for the research team.

As is well known, the biggest pain point of offshore oil and gas field development is the high operating cost. "We cannot conduct frequent logging and testing operations like onshore oil field development, which is too expensive," said Li Zhong.

How to fully utilize existing wellbore conditions to obtain as much oil and gas reservoir data as possible? Underground monitoring is like an "old Chinese medicine" giving signals to the reservoir and wellbore. Accurate signals are crucial, and the accuracy and reliability of monitoring tools are crucial.

At the beginning, we used single point electronic temperature and pressure gauges, but their reliability rapidly decreased under high temperature and pressure, often failing in less than a year, and unable to achieve multi-point monitoring, "said Li Mengbo, a drilling engineer at CNOOC Research Institute.

The research team shifted their focus to fiber optic monitoring technology. Fiber optic technology can indeed achieve multi-point distributed monitoring, but its accuracy is also too low for underground monitoring in offshore oil fields.

What should we do?

Li Zhong, who has been walking all the way from the grassroots oil field, has a tenacious spirit of stubbornness. Previously, he relied on this strength to lead the team to conquer multiple key core technologies and open the door to the oil and gas treasures in the South China Sea.

Fiber optic monitoring has been widely used in bridges and tunnels in China, but why is it not well applied in oil wells? With this question in mind, Li Zhonghe's team traveled all over the country.

Seeking advice from experts on the mechanism of fiber optic sensing, visiting fiber optic rod manufacturing enterprises to understand the process of fiber optic wire drawing preparation, conducting research on the process of fiber optic cable production at fiber optic cable manufacturers, and visiting Xijiang Oilfield in the South China Sea to understand the usage of foreign companies' underground monitoring and control products... Finally, the research team proposed the idea of femtosecond array fiber optic grating monitoring, which is the first time in the field of oil well monitoring.

After a year and a half, the research team came up with a feasible plan and the project was successfully approved.

Put on protective clothing for fiber optic cables

After the plan was determined, the research team quickly built a testing device for the underground oil, gas, water environment and high-temperature and high-pressure conditions.

The initial test results gave us a head start, "Li Zhong said. According to conventional bare fiber testing, it cannot adapt to the high-temperature environment underground. After a few hours, the loss quickly reaches saturation and cannot be used for a long time in oil wells.

Oil well fiber optic cables are usually protected by fiber optic coatings and fiber optic cable structures. Testing bare fibers alone cannot accurately simulate the actual situation of fiber optic cables working in underground environments. Therefore, it is necessary to "wear protective clothing" on the fiber optic cables before testing.

We must quickly adjust the plan, and both foreign and onshore experiences can be used for reference. However, we still need to embark on a path of independent innovation that is suitable for China's offshore oil fields, "said Li Zhong.

He encourages the team to broaden their thinking and boldly envision.

He combined party building with research and development. When conducting research on party building, he took the progressiveness nature of the party as the cutting point, let each branch "reveal their own resources", talk about ideas, and mobilize the enthusiasm of the whole team.

After brainstorming, the research team began a new round of analysis, testing, and improvement, selecting various fiber cores, coatings, and cable skin materials to analyze the impact of different grating indicators on sensing.

After thousands of experiments and tests, they finally found the optical fiber "protective clothing" suitable for the special downhole environment, completed the optical fiber monitoring system scheme and engineering prototype of high-precision, high-density communication integration for offshore oil wells, realized high-precision distributed temperature, pressure, acoustic wave monitoring, established the evaluation system and evaluation standards for the reliability of oil well optical cables, and filled the gap in offshore oil well monitoring.

At present, this monitoring system has been applied in Shanxi Linxing Gas Field, providing a large amount of data support for the optimization of production operations in the oilfield.

Remote control of underground "faucet"

With the data available, how can on-site operations be controlled based on the data?

The underground intelligent sliding sleeve is a key component, "said Sheng Leixiang, a completion engineer at China National Offshore Oil Research Institute. The intelligent sliding sleeve can achieve remote control without moving the pipe string, and is the last step in building a closed-loop offshore intelligent oilfield.

Oil and water coexist. In an oil layer, the viscosity of water is lower than that of oil, and the flow rate is fast. Once water is seen in the wellbore, most of the produced water is water. When encountering this situation before, it was usually necessary to stop production for maintenance and block the water outlet to ensure the smooth progress of oil extraction operations.

And the intelligent sliding sleeve is equivalent to a "faucet". Once it detects water or a tendency to see water at a certain location in the oil layer, it can turn the "faucet" at that location to reduce water outflow and promote the flow of crude oil at other locations in the oil layer. But the difficulty lies in how to easily and reliably control the intelligent sliding sleeve.

We have considered power control solutions, but the reliability of electronic components will rapidly decrease under high temperature and pressure conditions. At present, electronic control is not suitable for permanent monitoring underground. However, conventional hydraulic control solutions require multiple hydraulic control pipelines to be inserted for multi-layer control, which is not conducive to on-site operations. Li Zhong proposed that the research direction should be focused on hydraulic control with higher reliability, We can consider using one hydraulic pipeline to achieve online intelligent control of injection and production for multiple reservoirs underground.

Can a hydraulic pipeline achieve multi-layer control underground? This is another solution that no one has tried before, which integrates the reliability advantages of hydraulic pressure and a simpler string structure.

After several program optimizations, the final intelligent sliding sleeve product was successfully tested in the well on land. At present, the intelligent sliding sleeve has been used in many oilfields of CNOOC, reducing the high operating costs caused by Drillship workover, and providing support for production performance optimization and refined reservoir management.

Without any pause, Li Zhong immediately led the team to carry out project preparation and plan formulation for the second phase. The acceptance of the project is only the first step of a long journey. We need to continuously summarize and improve, increase promotion and application efforts, and make the 'information artery' of offshore smart oil fields smoother, providing a 'good recipe' for increasing reserves and production in offshore oil and gas development

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