An Evaluation of the Semi-Coupled Scheme for the Analysis of Floating Production Systems

Abstract

Analysis techniques and numerical formulations are available in a variety for mooring and riser designers. They are applied in the different stages of the design processes of floating production systems (FPS) by taking advantage of both the accuracy of results and the computational costs. In early design stages, the low computational cost is more valued with the aim of obtaining fast results and taking decisions. So in these stages it is common to use uncoupled analysis. On the other hand, in more advanced design stages, the accuracy of results is more valued, for which the use of coupled analysis is adequate. However, it can lead to excessive computing times. To overcome such high computational costs, new formulations have been proposed with the aim of obtaining results similar to a coupled analysis, but with low computational costs. One of these formulations is referred as the semi-coupled scheme (S-C). Its main characteristic is that it combines the advantages of uncoupled and coupled analysis techniques. In this way, analyses can be performed with very fast execution times and results are superior to those obtained by the classical uncoupled analysis. This work presents an evaluation of the S-C scheme. The evaluation is made by comparing their results with the results of coupled analyses. Both type of analysis were applied in a representative deep water platform. The results show that the S-C scheme have the potentially to provide results with appropriate precision with very low computational times. In this way, the S-C scheme represents an attractive procedure to be applied in early and intermediate stages of the design process of FPS.