Analysis and assessment on anchoring capacity of NANHAI 8 drilling platform with effects of internal solitary wave current are considered

During the drilling operation of an oil field in the South China Sea, NANHAI 8 drilling platform has encountered the action of internal solitary wave current, and certain effects have been left on the platform mooring system and drilling operation. Pursuant to the unique environmental conditions of internal solitary wave current in the South China Sea, the anchoring capacity of NANHAI 8 drilling platform has been analyzed and assessed. At first, the platform mooring system configuration and marine environment have been introduced. After that, the anchoring capacity assessment has been conducted based on the original design environmental conditions of platform. With regard to the hydrodynamic calculation of platform, according to the three-dimensional potential flow theory, by virtue of HydroD and DeepC software of DNV (Det Norske Veritas), the hydrodynamic analysis has been conducted on No. 8 semi-submersible drilling platform in the South China Sea, and the dynamic balance equation of finite element model of coupling motion spatial dispersion of platform system has been established. The positioning capacity of platform under the action of internal solitary wave current has been assessed in an emphasized manner, the platform deviation, anchor cable tension, and anchor horizontal load under the action of different current speed of internal solitary wave current have been analyzed, and the engineering suggestions which may be referred to by the platform operator have been proposed.