Research On Motion Analysis And Reduction Of Vibration Of FPSO With Soft Yoke SPM System

With the rapid development of national economy and the increasing demand for energy, energy shortage has become a bottleneck which impedes the further development of economy. In recent years, due to the long-term and large-scale exploitation of onshore oil and gas, the precious natural resources are on the brink of depletion. All countries in the world have turned their attention to the ocean which is rich in oil and gas resources.As the offshore equipment with advanced technology, high added value and most promising application potentiality, FPSO has become the most crucial facilities for exploiting oil and gas. After decades of development, the studies on FPSO made by foreign companies tend to be mature. Although the relevant domestic researches started late, they have broke through several technical difficulties and made some leading results on the basis of the foreign advanced technologies. However, China is still lack of practical engineering experience about the analysis and design of overall FPSO system. Recently, there were several mooring failure cases which were caused by the mooring system breakdown. It illustrates that more theoretical and experimental researches about the design of single point mooring system are necessary to carry on.This paper is based on Bohai Mingzhu’s soft yoke single point mooring system in Bozhong25-1oilfield. With site monitoring, it is found that soft yoke mooring system resonates frequently in the marine environment. The flaws of steel arm mooring system are summarized. Then the mechanism research is carried out to figure out the reason which results in the resonance. Without affecting the stiffness of mooring, the ballast tank is transformed into TLD system with vibration damper for the purpose of shock absorption. First, created the equation of motion of the mooring system, then took the measured power spectrum of hull displacement as input variables, gotten the structure characteristic and dynamic response through the complex modal analysis method and the pseudo-excitation method. This paper demonstrates the possibility of applying TLD system to soft yoke mooring system, and provides theory basis for the hardware-in-loop simulation damping experiment of soft yoke in the future.