中文摘要：

为研究双层底结构Sevan钻井储油平台在南海海况下的运动响应特性，建立SEVAN650平台的ANSYS有限元模型，将模型导入水动力分析软件AQWA进行数值计算，得出双层底结构SE—VAN650钻井储油平台的垂荡、横摇、纵摇运动响应幅值算子曲线，进而分析SEVAN650平台在南海海况风暴自存状态下的运动特性。研究表明，在风暴自存状态下，双层底平台的垂荡、横摇、纵摇的固有周期大于单层底平台。随着双层底平台直径的增加，平台的固有周期和垂荡最大响应幅值逐渐增加，平台横摇和纵摇最大响应幅值先增加后减小，在直径87．5m时达到峰值，双层底结构的使用效率逐渐降低。由于双层底直径85nl平台的固有周期已在风暴情况波浪周期外，在风暴作用下平台不会发生共振，因此SEVAN650双层底直径85m平台能够满足在我国南海生产作业。

英文摘要：

In order to study double bottom structure Sevan offshore oil platform dynamic response in the South China Sea, SEVAN 650 platform models had been built by using the ANSYS software, and then the models were imported into hydrodynamic analysis software AQWA for numerical calculation. The heave, roll and pitch response amplitude operators in the South China Sea storm survival condition were obtained for platform dynamic response characteristics. The heave, roll and pitch natural periods of single bottom structure are below double bottom struc- ture. Both the natural period and the maximum heave response amplitude gradually increase with the increasing of double bottom platform diameter, and the maximum roll and pitch response amplitude first increase in the peak of diameter 87.5 m and then decrease. Due to the diameter 85 m platform natural period is far away from the storm sit- uation wave period, the diameter 85 m platform meets the production operations in the South China Sea.