The Structure And Hydrodynamic Analysis Of The New Type Extend Tension Leg Platform

With the gradual exhaustion of the onshore and offshore oil resource exploitation, a number of new type of platforms that suit the deep-water environment come into sight. Meanwhile, the exploitation and development of China in the South Sea becomes so urgent that there is no time to delay. Among all these deep-water platforms, tension legs platform (TLP) has high cost performance because of its favorable hydrodynamic performance, excellent resistance to extreme environments, and as a type of half-compliant and half-rigidity platform, it is widely used and developed, being one of the major ocean deep-water oil production platform. Currently, TLP has developed into the second generation (including Seastar TLP, Moses TLP and ETLP) from the first generation Classic TLP. Currently, the research of China in this field is still at the initial stage in China. As a result of the unique environment condition of South Sea, it is urgent to design a type of TLP platform that suits the south sea. And many specialists and scholars agree with the good motion performance and economic effectiveness of TLP, at the same time they try to optimum the structure form of TLP.This article mainly discusses the following aspects:1. Under the condition of inheriting the advantages of ETLP and abandoning tits disadvantages, a new ETLP platform is designed to suit1500m water depth in South Sea. The new platform is combined with four columns and a circle pontoon, and the circle pontoon is welded with four box beams. Compared with the additional TLP, it reduces the number of block and welding joint because of the whole of extension structure and pontoon. The welding joint between extension structure and columns can be ignored, which enhances the strength and reliability of the structure. 2. Based on the three-dimensional potential flow theory, it uses the theoretical analysis with numerical calculation to research the dynamic characteristics of TLP in frequency domain. It calculates the added mass coefficient, the damping coefficient of potential flow and response amplitude operator etc., which acts on the platform. The output result indicates that the added mass and damping of ETLP both reach a good magnitude, and the new ETLP has excellent motion characteristics. Besides, all the frequency domain calculation results can be used for time-domain coupling analysis and calculation of the platform.3. it analysis the structure strength of the new platform whose main dimension has be confirmed, and then selects aggregate and the distance between the aggregates.The analysis results show that the motion amplitudes in each direction of the new platform are very small. The motion amplitude of pitching, rolling and yawing can be nearly ignored, and especially, the motion amplitude of heaving direction is no more than0.3m. Furthermore, each period of motion is within the inherent period of TLP.