Dynamic Response And Safety Analysis Of Semi-submersible Platform Due To Wind And Wave Environmental Loads

There are large amount of oil and gas resources in the ocean.With the constant depletion of the land and shallow-sea resources in recent years,the emphasis has been turned to deep-sea area for more energy reserves.Deep-sea platform is the fundamental tool for the exploitation of marine oil and gas resources.Among others,semi-submersible platform,as a representative of deep-sea floating platforms,is developing towards the purposes of a higher depth,better economic efficiency and stronger adaptability.At the same time,the harsh marine environment that is always encountered in the deep-sea region requires higher standards on the structural and safety designs for the floating platform projects.In this paper,structural characteristics and application prospective of semi-submersible platform are elaborated,and a‘6^th generation'domestic offshore oil drilling platform is taken out for analysis.The numerical simulation of time history of wind velocity is conducted,and non-steady-state numerical simulations of the wind fields around the structure under various wind pressure loads,dip angles and wind directions are carried out on FLUENT software,while the computational domain regions,boundary conditions,turbulence model and other issues are discussed.The most unfavorable condition is also determined based on the numerical results.A finite element model of the semi-submersible platform and its mooring system is established on ANSYS software.The shaping analysis of mooring system under the static condition and gravity load is evaluated.By using the Newmark-?method,the dynamic responses of semi-submersible platform system under the most unfavorable condition of the wind and wave environmental loads are obtained.Also,the structural reliability of the semi-submersible platform is also analyzed by using Monte Carlo method.