| The oil imports in our state increased year by year for the inadequate oil reserves and a large amount consumption, also domestic key oilfields have entered late development and the capacity continued to shrink. Our state dependence on foreign oil increased by55%in2010, which has the second consecutive year exceed international safety cordon50%. The International Energy Agency predicts that China on the international market dependence will reach82%in2030, which is far more than the national energy security alert line. Therefore, the petroleum resource constraints are becoming increasingly prominent in the state sustainable economic and social development.According to the geological survey,45%of the worldwide total oil resources come from the ocean, in which the57%area is the continental shelf seabed oil and gas sedimentary basins, so the ocean provides a new direction for our state energy development. In recent years, nearly50%of global major oil exploration comes from the deep water, which includes Mexico gulf, Brazil southeast coastal waters, Guinea coast in West Africa and the South China Sea, also the deep water development has become the trend of today’s oil development. For now, the main carrier of the deep water oil development is the offshore oil platform equipment and technology, which becomes the strategic core areas in states competition. In the above context, this paper carried out floating manufacture of the international first sixth generation cylinder offshore oil platform, in which the main content includes the following aspects:In the manufacturing process of the cylinder offshore oil platform, we proposed floating manufacture for the special manufacturing conditions and difficulties in launching, which has been successfully applied for a PCT international invention patent. When the workers use this method in operation, they first manufacture the platform bottom on the semi-submersible barge deck with the underwater rotating technology, and then complete the whole platform on the floating bottom by means of removing the semi-submersible barge. This method provides ingenious solutions to manufacture a large-size offshore oil platform on the limited-size semi-submersible barge, which is successfully applied to Seven Driller platform, and provides a theoretical basis for the promotion of floating manufacture of marine engineering equipment. The hydrodynamic analysis software AQWA was first used to comparative analysis of cylinder and ship offshore oil platform dynamic response in the South China Sea storm survival condition, and the results show that the heave, roll and pitch response amplitude of the cylinder platform are below the ship platform, and the inherent cycles are away from the wave period in storm situation, which represents the motion response and resisting capacity of cylinder platform is superior to ship platform. Then the AQWA software was used to analyze the double bottom structure effects on the the cylinder offshore oil platform dynamic response, and the results show that the heave, roll and pitch natural periods of double bottom structure are greater than single bottom structure, which are away from the wave period in storm situation. With the increase in the double bottom platform diameter, the structure use efficiency gradually reduces, so the double bottom meets the production operations in the South China Sea, which provides an important reference for the offshore oil platform structure selection.Mathematical theory model and optimization mehod of the underwater rotating technology is built in this paper. The model contains many practical requirements, such as the size of the semi-submersible barge, the area required for drilling oil and gas, the mass of the unit area in the bottom, the lifting capacity of the factory and the operation space for workers. The model of the underwater technology in the paper would first minimize the number of the rings in the bottom, second minimize the number of the block in each ring, and finally find the maximum underwater rotating angle. Sevan Driller offshore oil platform is employed to verify the correctness and validity of the mathematical theory model. On this basis the bottom blcok division method of cylinder offshore oil platform is proposed in this paper, which has been successfully applied for a PCT international invention patent. This research provides a theoretical basis for the promotion of floating manufacture.The mathematical theory model of the underwater rotating angle is built in the paper on the base of considering the platform and the semi-submersible barge sizes, and the underwater rotating apparatus with changeable rotating angle is proposed in the paper, which includes a pair of arc-shaped base, the hydraulic support, the arc-shaped hydraulic rail, the driving motor, power supply units and the computer. The apparatus has been successfully applied for national invention patent. Finally, the underwater rotating apparatus was successfully applied to build the Sevan Driller platform bottom, and the results show the model is correct and valid, which provides an important reference for the offshore oil platform construction.The method of controlling the block prestress in the FDSO bottom with the supports adjustment was proposed in this paper, which has been successfully applied for national invention patent. In floating manufacture of offshore oil platform, the platform bottom is built on the semi-submersible barge deck, in which the supports adjustment will cause different force imposed by the block weld, and we define this force as the block prestress. When you know the possibility block force in the future, you could exert a reverse force by the supports adjustment, which could reduce the block wreck possibility in extreme situations. Finally this method is applied to build the Sevan Driller platform bottom, which provides an important reference for floating manufacture of marine engineering equipment. |
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