Hydrodynamic Performance Analysis And Dynamic Characteristics Research Of Mooring System For Deep Sea Truss Spar Platform

With the increasing development of the society in the21stcentury, energy demand isbecoming more and more prominent. As the resource of land gradually drains away, the usage ofocean resource and energy has draw people’s attention and the development of Marine resourceand energy is also increasing, including the exploration of ocean oil and gas resources. During the30years’ reform and opening-up, the economic development of china has drawn the worldwideattention. The high-tech and energy industry have been developing so rapidly that our demand forenergy resources is also increasing. In order to meet the growing demand of energy, a lot ofoffshore oil platform emerged at the historic moment. The Spar platform is a kind of platformstructure which is used for deep sea oil exploration, production, processing, and storage and theadaptive range of water depth of which is500-3000meters. Therefore, it is of great importancethat we should investigate the movement performance of Spar platforms and their mooringsystems in complex marine environment.This study is mainly based on the investigation of the Truss Spar platform which is serving inthe Gulf of Mexico. By using the marine environmental parameters of Liwan3-1and adopting themethod of theoretical analysis and numerical simulation respectively, the hydrodynamicperformance and dynamic characteristics of mooring system are studied within the scope offrequency domain and time domain.In the ocean, Spar platform is under the effects of various environmental loads such as wind,wave and current, in which the loads generated by currents and waves affect the marine structurethe most. First, the paper introduces the characteristics and the current research of the Sparplatform simply from the development process of the Spar platform.The Truss Spar model is builtby using Ansys software. Based on the three-dimensional potential flow theory, I import theplatform of the model parameters to AQWA-LINE module. By defining the position of the centerof gravity and moment of inertia radius, I obtained the information of the hydrodynamic platform in different frequencies. The result shows that the Spar platform has excellent hydrodynamicbehavior and it could be used for the analysis of mooring system.By taking Spar platform and mooring system as a complete system of dynamic coupling andconsidering the combined effects of wind, waves and currents, and other environmental loads, Ianalyze the hydrodynamic performance in time domain under the severe sea condition and drew aconclusion on the motion responses and mooring force of the cable of the Spar platform. I foundthat under the severe sea condition, the motion responses and mooring line tension can satisfy therequirements of specification.Through the analysis of the comparison of the numerical simulation results, the change ofcenter of gravity height, the mooring grouping，the initial angle between the mooring lines andseabed，and different circumstances, such as a piece of cable breakage of the Spar platforms， theimpact of sports performance and their mooring system are studied respectively in order to explorethe change rule of platform and mooring system coupling movement, and provides a certainreference basis for the follow-up of Spar platform optimization design.