Research On The Hybrid Model Test Of Deep Water Semi-Submersible Platform

With the development of the economics in our country, and the increasing demand of the oil consumption, the main oil filed on land began to decrease its production, and the exploration has become harder. The contradiction between supply and demand has been highlighted. There is a rich resource of oil and crude gas in South China Sea. China's first 3000m deep water semi-submersible drilling platform "Haiyang Shiyou 981" has completed its design period, and been constructed at the end of 2010.Researchers proposed hybrid model testing technique, which combines model test at truncated water depth and numerical simulation. Deepwater mooring lines are cut at the truncated water depth, and an equivalent truncated mooring system is designed to use in the model tests, and the model test results are reconstructed and extrapolated into full depth by means of time-domain coupled numerical software.In this paper, a truncated mooring system is designed to meet the needs of the 3000m SEMI model test. The water depth truncation design is taken for the 1500m working depth, and the width truncation is taken for the 500m working depth, in which condition the mooring system has a too large span, cannot be layout in the basin. Chooing the key static characteristics as the objective function, the truncated mooring system should have a simulation with the full depth one. The model test is carried out in the Deep Water Basin of Shanghai Jiao Tong University. With the results, the reconstruction and extrapolation give a good prediction of the hydrodynamic response with the full depth system.Two truncated mooring system at 250m and 125m are designed for the 500m full depth, to get a verification and research on the difference of dynamic characteristics. And 3 truncated mooring systems are designed to research on the influence of the change of mooring lines at waterline.