6-DOF Motion Assessment of A Hydrodynamic Numerical Simulation of A Semisubmersible Platform Using Prototype Monitoring Data

Hydrodynamic numerical simulations are used to conduct structural analyses and inform the design of engineered marine structures.In this paper,a hydrodynamic numerical model of“Nanhai Tiaozhan”(NHTZ)FPS platform was established according to its design specifications.The model was assessed with two sets of field monitoring data representing harsh and conventional sea states.The motion responses of the platform according to the measured data and the hydrodynamic simulation were compared by reviewing their statistical characteristics,distributions,and spectrum characteristics.The comparison showed that the hydrodynamic model could correctly simulate the frequency domain characteristics of the motion responses of the platform.However,the simulation underestimated the reciprocating motions of the floating body and the influence of slow drift on the motion of the platform.Meanwhile,analysis of the monitoring data revealed that the translational degrees of freedom(DOF)and rotational DOF of the platform were coupled,but these coupled motion states were not apparent in the hydrodynamic simulation.

An Overview of Structural Design,Analysis and Common Monitoring Technologies for Floating Platform and Flexible Cable and Riser

Offshore oil and gas development plays an important part in the global energy sector.Offshore platforms and flexible pipes are the key equipments in the whole offshore oil and gas development system.Because of the randomness and uncertainty of wave and current loads in the ocean environment,the structural design and mechanical analysis of the marine equipment can be highly complicated.Therefore,this paper reviews the recent works of the theoretical model,numerical simulation,and experimental test in three research areas:hydrodynamic analysis of offshore platforms,structural mechanics analysis of flexible pipe and cable,and monitoring technology of offshore floating structures under marine loads.By analyzing their main research methods and key technical difficulties,this paper provides theoretical basis and technical support for the reliability engineering application of offshore platforms and flexible pipelines.Also,China is relatively backward in the design of marine floating platform,the design,analysis and testing of flexible pipeline and cable,as well as the marine equipment prototype monitoring technology research.Calling for breakthroughs at the earliest possible stage in the above fields,prime research should be focused on and strategic planning should be made to deal with“key areas and stranglehold problems”.It is of great significance for the development of China's deep-sea energy and resource development of independent technology and on time to achieve the“carbon peak”national strategic objectives.