Research On Characteristic Of Mooring System Of Spar Platform

As the demand of oil increasing and the resource onshore being used up, along with the national economic fast development, the exploitation of deepwater oil resource stares us in the face nowadays. As the result, the investigation of deepwater structural dynamic response which contributes to technology of deepwater oil exploitation, especially about the spar platform which fast developed in recent years, gain high recognition from technological personnel in this field. This paper mainly talks about the dynamic response of spar, and strives to find couple methods which can concern with the interaction of spar's main body and mooring system, and give a description of the dynamic response of spar as precise as possible.First of all, on the base of flexible bar theory, mooring line & riser's kinetic differential equation is established, regarding the feature of mooring line & riser's distortion. Finite element method is applied to discrete the kinetic equation in time domain, and to get the nonlinear second order ordinary differential equations and steps to solve the static and dynamic equations. The method to simulate the mooring line in this paper is proved feasible by numeric calculation of a mooring line with large elongation.Secondly, according to 3-N potential flow theory, the frequency-domain kinetic equation of free-floating Spar is established, and Spar is converted into equivalent mass element, so as to solve the dynamic equation of Spar and mooring line & riser. Besides, to settle the problem of calculation of Spar's dynamic parameter in WAMIT which is hydrodynamic analysis software, a way to mesh grid with Ansys, popular finite element software, is put forward in this paper. At the end of this paper, calculation sample of a Spar is given, and the result shows that the model of spar dynamic response mentioned in the paper is correct, and the mesh grid for hydrodynamic analysis is reasonable.