Numerical investigation on mooring line configurations of a Paired Column Semisubmersible for its global performance in deep water condition

Abstract

The advances observed in the offshore-renewable industry include the recent development of a deep draft paired column semisubmersible platform developed for application on dry trees in Gulf of Mexico (GoM). These developments led to the recent innovation of the Paired Column Semisubmersible by Jun Zou of Houston Offshore Engineering. This paper presents a detailed investigation on the mooring line analysis for two different configurations on the hull of a Paired Column Semisubmersible (PCSemi). The numerical research of the PCSemi platform coupled with mooring lines was conducted, and the model was validated. Two different mooring configurations were investigated: Chain-Polyester-Chain (CPC) and Polyester-Polyester (PP) configurations, with dynamic coupling in frequency domain (FD) and time domain (TD) using ANSYS AQWA and Orcaflex. A comparative study of the mooring lines is also investigated in 2,438 m water depth at GoM, using 16 mooring lines with catenary mooring design. Results of this study gives the natural period of floating PCSemi's heave motion ranged from 21s to 22s. Also, the effect of a damaged mooring line increased the tension in other mooring lines. Lastly, the CPC configuration has a smaller amplitude for wave-frequency platform motions compared to the PP mooring configuration from the depicted PCSemi global performance.