The Dynamic Response Analysis In The Random Wave Load Of The Spar Platform Based On ANSYS Software

With the gradual depletion of oil and gas resources onshore and offshore, the deep-sea oil and gas development has become an inevitable trend to meet thegrowing demand for energy.And accompanied by human being's speeding up of the pace towards the deep sea, all types of marine platforms of the deep sea emerge. But in the long run, the mooring of floating oil production platform is the the main focus of the future development. Spar platform and Tension leg platform are the representatives of the new oil production platforms. They are still continuing to apply the new technology and they are moving towards greater depth, better economy, more adaptive in the rapid development of the platforms. However, with the increasing of the depth of the water, the marine environment has become more complex. This results in a higher demand of the structure and performance of the marine structure, which is a higher challenge to the project and the scientific fields.This paper has employed the ANSYS simulation software and adopted the methods of the PSD with the vibration simulation. This thesis uses the world's first Truss Spar platform -Nansen Spar platform which locaterd in the Gulf of Mexico as a model. This paper does the Dynamic Response Simulation Research under the influence of the random wave load (JONSWAP wave spectrum). Two different calculation methods were compared in this paper, including the mode method and vibration with the PSD method. This paper has taken two different frequency of random wave spectrum dynamic response simulation with the PSD and vibration simulation. The results show that: the vibration of the Spar platform is from the the center to the upper and the lower part of the truss in modal analysis. The pitching, rolling and heaving of the platform are all very intense. One of the most influential movement is the heaving movement. The dynamic response of the Spar platform in the random wave load and the frequency of the wave energy are the same in the no-resonance frequency range. Among which the speed of response, acceleration response and the displacement response of the Y direction of Spar platform is the largest. The response to swing around the X-axis is the largest, and for different parts of the dynamic response of values, the cylinder (near the center of gravity )of the platform is the lowest. The Y direction of the board of the dynamic response is the largest.With in the resonance frequency range, the resonance peak of the response of the displacement of the Spar platform is bigger than the the peak of the wave. The swing will be very strong and the response rate is only slightly little. It has little effect on acceleration response. Although Spar platform drafts deep and has low center of gravity, but we can not be ignore its influence on its slow drift in the low-frequency regional.