| The mat supported jack-up platform with an oil storage tank is known for its oil storage capability and oil producing continuity. So the jack-up platform is fit to the development of marginal oil field for its reducing cost and increasing interests. It is oil-water displacement technology, thermal insulation technology of crude oil, oil riser installation technology and so on which are applied to store oil in the mat. The research of those technologies would be focused on. And the effect of mat on the mechanical behavior of legs would also be studied in the progress of platform migration and lowering.The oil storage tank using oil-water displacement technology is classified. Two kinds of oil storage tank, the oil storage tank using passive oil and water displacement and the oil storage tank using active one, are designed and the working principle and working process of them are illustrated. To make the oil-water isolation layer move smoothly, the inlet type of oil storage tank is investigated both in theory and simulation. And the relation of the outflow of cross sections with three inlets is deduced. When the oil was stored in mat, seawater in the tank should flow back and forth between the main deck and the oil storage tank to diminish the risk of pollution. Material of the soft membrane making up the separation layer is selected. The passive oil-water displacement oil storage tank experiment is performed to prove the accessibility of oil-water displacement technology. The rule of oil-water isolation layer is also researched. With some concerned problems improved, oil-water displacement technology is researched further by general model experiment of mat supported jack-up platform.The thermal barrier effect of the oil-water isolation layer is researched by the steady-state heat transfer method in the aspect of heat flux through the oil-water interface. To provide theoretical basis for ascertaining the duration of the oil-water displacement process and selecting the material of isolation layer, the oil heat dissipation model is built. The transfer law of oil heat during the progress of oil-water displacement is studied. By the research of heat preservation, the rule of heat dissipation during oil storage was obtained, which could provide guidance to decide the period of heating cycle.Installation of oil riser between the mat and main deck is important. A static analysis is conducted, comparing different installation’s effect on the riser mechanics performance. The optimal installation method is chosen by considering the result of dynamic analysis of riser. Because the riser’s stress state could be improved for the installation of pipe clamp, the number and installation method of pipe clamp is studied in static way. The mechanical behavior of single pipe clamp, double pipe clamp and three pipe clamp is studied. Finally, the installation of pipe clamp of rise is proposed.Using the calculation method of ordinary jack-up platform in the working condition of migration, the rolling inertia moment and the total bending moment of mat supported jack-up platform in the same condition are researched. The formula for moment calculation of pile legs is deduced. Then the relationship between bending moment of pile legs and the position of mat is concluded, which provided guidance for the migration of the mat supported jack-up platform. By comparing the bending moment of pile legs of ordinary jack-up platform and mat supported jack-up platform, the influence of mat on the mechanical behavior of pipe legs is studied.In the process of pipe legs lowing, the mat, a large-scale square submerged body, is immersed into the sea completely. So the diffraction effect of the incident wave and the effect of the free surface need to be considered. Wave and current forces on mat are calculated using Froude-Krylov method, which is a approximate method based on the modal test. So the relationship between the position and F-K force of the mat is attained. Then the variation regularity of maximum stress belonging to the ordinary jack-up platform and the mat supported jack-up platform is investigated respectively during the progress of pipe legs lowering. Finally, the effect of the mat on pipe legs is studied. |
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