Study On The Character Analysis And Parameters Optimization For The Mooring System With Buoys Of A Semi-submersible Platform

The semi-submersible platform is mainstream product equipment in offshore exploitation.It is therefore crucial to design reasonably as well as learn carefully about its hydrodynamicand motion performance under wind, wave and current loads.In this paper, the plan of attaching buoys to the mooring system was proposed, the designparameter of the buoys was studied to see their effects to the mooring system character,optimize the mooring system, thus improve the low frequency performance as well as decreasethe in-plane motion character, advance the operation ability and safety of the platform.Firstly, the hydrodynamic model and the coupled model of mooring system was created,using commercial software AQWA as well as the time domain coupled dynamic analysismethod to analysis the motion character and mooring performance of the platform,comparison between numerical prediction and model tests are made to see the effectiveness ofnumerical simulation.Then, the mooring system with single buoy was modeled according to the initial mooringplan, model tests was also conducted to verify the accuracy of the numerical simulationmethod. Considering from both static and dynamic aspect to learn how the design parametersof the buoys (etc. location and size) could influence the motion character and mooring systemperformance, especially their performance under low frequency, useful conclusions werereached, an optimized mooring system plan with single buoy was proposed, showing greatimprovement in motion character and mooring performance after numerical calculation andevaluation.Finally, the mooring system with two buoys was modeled based on the one buoy mooringsystem plan, and the effectiveness of numerical calculation method was also verified by modeltest. Study was taken on how the parameters of the two buoys influences the motioncharacter of platform as well as the line tension performance, several meaningful conclusionswere made, as well an optimized2-buoy mooring system was proposed. Compared withsingle-buoy mooring system plan, a better optimized one was selected. The result of the studycould offer technical support to the design for mooring system with buoys under various waterdepths.