Dynamic Performance Analysis Of A MOSES TLP In Extreme Environment

With the development of technology,we know more and more about the ocean and pay more attention to the ocean energy.The study of the equipment for the development of ocean energy also makes great progress.At present,a variety of platforms have been put into use in the waters around the world.The dynamic response of the platforms in extreme environment has always been the focus which verifies the design and operation.The tension leg platform has been widely concerned as the vertical movement is small in deep ocean which is fit for dry tree oil production.The DNV SESAM is used for the dynamic response of a MOSES TLP.And the response characteristics of the platform have been summarized through the comparison with the measured data of the platform.The main contents are as follows:The use of the SESAM software is for the frequency domain and time domain analysis of the MOSES TLP.In the frequency domain analysis we can get the platform hydrodynamic parameters such as add mass and QTFs.Considering the second order wave effect on the platform in extreme sea conditions in the time domain analysis,the platform motion response in 100 years and 1000 years sea condition are calculated respectively.By the method of spectrum analysis the second-order wave influence to the platform hydrodynamic performance and the tendon tension has been discussed.The results of the difference and sum frequency calculation have great effect on the platform motion and the tendon tension.The difference frequency calculation mainly influent the motion of surge,sway and yaw and the sum frequency calculation mainly influent the motion of heave,pitch and roll,which affect the tendon tension directly.So the TLP should consider the second order wave in the design especially for the influence to tendon tension.To simulate the original sea condition of wind,wave and curent,the coupled dynamic method is applied to get the platform motion and the tendon tension.Spectrum analysis method is used to analyze the movement of tension leg platform and the change of the tendon tension in extreme sea condition.The comparison of calculation and measured data prove that the calculation are consistent with the measured data and verify the feasibility of the theory and the design.