Numerical Study On An Offshore Jacket Launching Process

With the increasing demand of power resource in recently years,the exploitation and take use of oil and natural gas has been a focused issue.Developing the exploitation of oil in ocean has been the main direction of national power resource exploitation. As the main structure in exploitation ocean oil, the manufacture, transportation and installation of ocean platform have been more and more concerned at the same time.The steel-foundation fixed platform is one of the widest been used forms in exploitation of ocean oil around the world, the amount of the kind of fixed platform, which lies in water between several meters to hundreds of meters in the sea, has been up to 90% of all kinds of ocean platforms.The jacket platform has been widely used in the construction of the oil platform. For the large platform, because of lacking the sufficient lifting capability, the jacket usually been pushed by hydraulic ram or tugged by winch so that the jacket could slide along the slipway on the barge after the jacket be transported to the assignation place.Once the jacket has been transferred at the only point that the jacket could overcome the friction, the jacket will slide and rotate and be separated with the barge. In this way the jacket will float on the surface at last. The process is the launch of jacket platform as we said on usual.So far there are many sorts of method have been developed in the field of launching jacket, such as empirical method, simply analysis method, experimental method and numerical simulation method.And the nonlinear finite element numerical simulation method is one of the most effective and most suitable for the practical situation.This thesis uses FEM and LS-DYNA fluid-solid coupling function to simulate the launching process by numerical simulation method, the finite element model include the platform, the air domain and the sea water domain. And the thesis will get the crucial data of posture such as the displacement of the center of mass,the velocity of the jacket, the buoyancy of jacket. On the basis the method, the thesis studied the influence of different parameters to the posture of the jacket, such as the difference of the initial velocity, the jacket mass and the initial angle of installation etc.According the research result in the different parameters,the issue will post the conclusion which is useful as guidance for advanced research.