Lady of substance in solving subsea challenges
1 December 2011
Ms Zheng Jiexin, engineer with a liking for subsea challenges.
Ms Zheng Jiexin was awarded the President's Graduate Fellowship recently. She is now pursuing her PhD studies in Engineering at NUS under Prof Andrew Palmer. NUS Keppel Professor Andrew Palmer, a leading authority in subsea engineering, has met Ms Zheng Jiexin in Dalian University of Technology three years ago during a conference trip when she was working on her master's degree on flexible pipeline.
Said Jiexin, "Prof Palmer gave me valuable suggestions I needed for my flexible pipeline research. I was really impressed by his expertise. These were the major reasons for my decision to continue my studies in NUS. Prof Palmer built a bridge between me and Subsea 7, one of the world's leading offshore engineering companies supporting this research project."
Commenting on her awarded the President's Graduate Fellowship, Prof Palmer, now her supervisor, said, "Jiexin has only been at NUS for 14 months, and has already completed an impressive amount of research, both experimental and numerical, as well as doing excellently in coursework and creating an admirable rapport with Subsea7."
Subsea pipelines are very important to transport oil, gas and other fluids in the offshore engineering industry. Her research concentrates on the overtrawlability and other possible mechanical damage of pipe-in-pipe system. In designing an effective subsea pipeline, one needs to take into consideration many factors, the thermal insulation is just one of those. "In order to enhance the pipeline's thermal insulation capability, pipe-in-pipe system was developed. This is a kind of pipeline with a modified cross section, a pipe or a pipe bundle inside a bigger pipe. A thick insulation layer can be added between the inner pipe bundle and the outer pipe to provide excellent insulation and this is widely used in oil industry," Jiexin explains. Overtrawlability is the ability of the pipeline to resist trawl gear impact and pull-over force. Trawl gear is a equipment used for bottom trawling in the fishing industry. Trawl gear is big and heavy, whose weight can reach 9000 kg with width of up to 17m.
"Trawl gear can move across the seabed at a speed of 3 m/s, and can hit a pipeline on the seabed causing damage. The trawl gear creates an impact force instantaneously, and is then dragged over the pipeline which gives the pipeline a pull-over force. Sometimes this damage is comparatively minor, but sometimes the damage is so severe that the pipeline is no longer fit for service and definitely has to be replaced. As the environmental concerns are more and more serious nowadays, it is very important to protect the pipeline on the seabed from damage. This requires a good understanding of the response of pipe-in-pipe system under impact and pull-over force," Jiexin elaborated.
Jiexin is establishing a model which can predict the response of pipe-in-pipe system under impact and pull-over forces. "My target is to assess the overtrawlability of pipe-in-pipe system, and protect the pipeline from mechanical damage. Now that I finished some of the experiments, I will develop them for dynamic conditions. I am also planning to do an underwater test to simulate the real condition when trawl gear hits a pipeline on the seabed. This will be very interesting," she said.
Her research will help offshore oil companies make sound and safe trenching decisions and hence save on unnecessary costs. And for Jiexin, there is no other work more satisfying than to come out with solutions to meet complex challenges.
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