| The advanced countries focus on the deep sea oil and gas development.The deep sea oil and gas exploitation form of USA is “floating drilling platform-subsea wellhead-subsea production system-submarine pipeline” mode.The main equipment is dry tree drilling platform,such as deep water tension leg platform(TLP)and deep-draft column platform(Spar),etc.Brazil's deep-water oil and gas exploitation form for the semi-submersible platform is “subsea wellhead-subsea production system-oil floating production,storage device” mode,using wet tree drilling platform and semi-submersible platforms.As a new type of drilling storage and offloading platform,FDPSO will become one of the important tool of deep water oil and gas development strategy.At present,there is a lack of experience in construction due to the lack of mature structures and corresponding technical guidelines.Starting from OCTABUOY designed by Moss Maritime,the following research works are focused on the hydrodynamic performance of the platform and the dynamic problems of heave compensation system.First,the traditional lifting compensation device and the new type heave compensation device are introduced,and their advantages and disadvantages are analyzed and compared.The basic working principle of FDPSO-TLD is described,the mechanical model of TLD is established and setting up the preliminary layout object of this platform and tension leg deck system design scheme based on OCTABUOY.The detailed layout description of the tension leg deck,underwater weight and key riser structure are given.Secondly,the marine engineering software AQWA is used to study the hydrodynamic performance and mooring characteristics of OCTABUOY multi column FDPSO.The motion and mooring characteristics of the platform under the 0 and 45 degree wave angle in the operation condition and the self-survival condition are calculated respectively.Meanwhile,platform test model based on the scale of 1:80 is made to conduct model test at Shanghai Jiaotong University ocean basin and fully taking into account the impact of the mooring system.The external environmental load of the platform was simulated.Through comparison and analysis of numerical simulation and test results,the reliability of the calculation results is verified.Thirdly,a coupling model of octagonal FDPSO,mooring system and heave compensation system is established.The hydrodynamic response and mooring line tension of the main body of the platform before and after the installation of TLD are analyzed and compared.At the same time,the heave responses of TLD and FDPSO are compared.The numerical simulation results show that the heave response of TLD is smaller than that of FDPSO,which proves that heave compensation of TLD has some heave compensation effects.Finally,the sensitivity analysis of the main parameters of FDPSO-TLD was carried out.The movement responses of the platform under different weights,platform center of gravity position,mooring arrangement and riser arrangement were compared and analyzed.The results show that the weight and the riser arrangement have a great influence on the heave movement of the TLD.The overweight of the weight leads to the increase of the cable tension,which leads to a more intense response of the heave.The influence of platform center of gravity position is small.The mooring line mainly constrains the horizontal movement of the platform and has less effect on the vertical movement of the structure.When the cable arrangement is changed,the platform heave movement is not changed much.The research shows that when the TLD is set,the magnitude of the heave of TLD is smaller than that of the FDPSO main body,which proves that the FDPSO-TLD system has some heave compensation effects. |
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