| Jack-up drilling platform is currently the most widely used in important carrier of gas exploration and development, its towing condition is very dangerous working condition, there were painful lesson in its development history, so since Jack-up drilling platform towing safety issues caused great concern worldwide, while the Jack-up platform mooring positioning process in place is one of the key technologies. In this paper, a reference to a type of Jack-up drilling platform and its mooring system was used to study, coupling time domain analysis was made by hydrodynamic software ANSYS/AQWA for target platform at towing and place conditions, and the optimization of the mooring system was studied by using joint multidisciplinary design software Isight, seeking the best location control strategy for platform. Specific studies are as follows:(1) Hydrodynamic analysis theories of offshore structures was discussed, including the marine environment(such as wind, waves and currents) calculation theory, the calculation of floating body movement(Morison equation) and three-dimensional potential flow theory, solving the flow field velocity potential of the Green’s function method and the AQWA module theory.(2) The basic structure of Jack-up rigs was designed according to the design specifications, a platform hydrodynamic model was created, its overall layout and cabin were designed, Platform focus was computed by platform structure and its variable loads distribution, On this basis, the platform hydrodynamic response was made with frequency domain analysis, the added mass, radiation damping and motion response of the platform were got.(3) Towing motion simulation was made for the the towing system consisting of jack-up platform-streamer-tug based on potential flow theory and wave radiation, diffraction theory, the analysis for towing system in still water and stream towing was made with taking the combined effects of storm flow into account, and the impact of major factors on the stability of the platform towing was studied.(4) Coupling time domain analysis was made for Jack-up drilling platform mooring system in place working conditions under the combined effects of wind and waves flow, hydrodynamic model of self-elevating platform mooring system was created, analysis for platform stability was made in the process of lowering pile, the relationship between sport response and the loads of its mooring state were studied, the variation of mooring line force with the perspective for environmental loads and draft was explored, at the same time, the reliability of the numerical model was verified by using the test results of movement response for jack-up drilling rig mooring. The effect of movement response to platform by winch was studied based on this, an effective way for real-time control platform mooring system has been explored.(5) The mooring length optimization for mooring system was studied by jointing multidisciplinary optimization software Isight, based on the coupling time domain analysis for Jack-up drilling platform mooring system. The optimal positioning methods of platform was researched, The optimal control strategy for self-elevating platform mooring system was achieved, a fast and accurate optimization system took shape, the platform can be positioned smoothly and exactly, a theoretical reference for the jack-up rig positioning method research and mooring system design has been provided. |
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