In order to properly design the mooring and offloading equipment, and assess the availability of Floating Liquefied Natural Gas (FLNG) units during the engineering phase, TechnipFMC has paid a particular attention to the operability prediction of LNG offloading operations. For the FLNG projects currently under construction, the chosen offloading solution is the Marine Loading Arms (MLA) technology with the LNG carrier (LNGC) moored in side-by-side (SBS) configuration.
In this paper, an improved methodology using Monte Carlo simulations is proposed to create a representative sample of a typical hindcast for North West Australia, assuming the case of a 147,000 m3 LNGC moored side-by-side to a TechnipFMC in-house design FLNG. It is shown that the random sampling is very well suited for large number of dimensions implied by the driving parameters (e.g. significant height, peak period, relative heading) of multiple wave partitions. In a second step, different multidimensional scattered data interpolation techniques are evaluated in order to further improve the accuracy. Since this would not be practical in time-domain and because the objective for this study is to compare the sampling and interpolation techniques to a benchmark on the whole hindcast, the vessels’ motions and SBS offloading operability are calculated in frequency-domain. The conclusions could also be applied to time-domain simulations. The paper also presents the sensitivity studies to the different interpolation methods and their key parameters and discusses the suitability of the proposed solutions.