Motion Response And Structural Strength Analysis On Upending Of Spar

The oil consumption of China increased rapidly year by year, so did the dependence rate on foreign oil. It becomes more and more necessary to master technology of deep-water oil exploration to increase domestic oil production. Spar platform has superior motion and stability properties, it is very adaptable to south ocean conditions in China. But there is a complex upending process before Spar begins its production service, its motion and structural loading are substantially different from the exploratory life, needing special design and verification.This paper is supported by Major projects of national science and technology named "Structural analysis of deep-water platform".This paper analyzed the characteristics of upending process, established an analysis method based vector form intrinsic finite element (VFIFE), developed an upending analysis software. Then the motion response and structural strength analysis are made, and correctness of the method is verified by model test. The main conclusions are summarized as fallows:(1) The upending of Spar is an unconstrained and large displacement process, with time, displacement, mass and load coupling changes. The paper considered hystatic pressure, gravity, damping force, add-mass of water and other factors'effects on upending process, established coupling relationships of each factor, proposed a VFIFE-based analysis method on upending.(2) A platform example was analyzed based on the proposed method, the motion law during upending process was obtained.(3) A parameter sensitivity analysis was performed, the influence degrees of various factors were obtained.(4) A structural strength analysis was performed, the stress vary laws of different members of platform were obtained.(5) The program of model test of upending was introduced, the results were analysed. The upending test of test platform was simulated by software, correctness of the proposed method was verified.