| Floating Platform is playing a more and more important role in the contemporary offshore oil and gas extraction. China's research to floating platforms start late, but it's developing very fast. The semi-submersible platform "Hai Yang Shi You 981" is completed in Feb.26th in 2010,which is the first sixth generation drilling platform designed and built independently by China.It can be used when the water depth reaches 3000m,and it stands for the highest level in the world's offshore oil drilling platform technology. Mooring system keep the floating platform to move in the allowed region and it's very important to ensure the safety during drilling and oil and gas extraction. Thus, research on mooring system is really important.Thus design of mooring system is not imperfect, and there are many accidents due to failure of mooring system. In this paper, the design of mooring systems are summarized and researched. In basic design, the design parameters were discussed based on theoretical models. In detailed design, the study on analysis method is carried out. There are three methods for research on the mooring system. The first one is numerical simulation, but it can not simulate the mooring system exactly because of the complexity of the environment. Model test is another method, but it can not describe the real response of mooring system as a result of uncertainty of the similar scale ratio. Relatively, the field monitoring is a better one. The real response of mooring system can be obtained in this way. However, it has its own disadvantage. We can not get every response during the extreme sea condition. Therefore, with the examples of LH11-1 FPS and the Mingzhu FPSO, a new method of evaluation and analysis to mooring system is proposed in this issue, which is combined by field monitoring and numerical simulation. The numerical simulation can be checked during the normal condition by monitoring result, and it can be used to evaluate the response under extreme condition. Taking the mooring systems of LH11-1 FPS and the Mingzhu FPSO as examples, the method of evaluation and analysis to mooring system based on monitoring is proposed in this issue. |
