Abstract
Recently, the FLNG projects have been developed for the LNG production at near shore field with shallow water depth. For the permanent mooring of FLNG in this field, several mooring types such as Jetty, Yoke, fixed structure (strut) and spread mooring are considered up to now. In the development of near shore (NS) FLNG projects, one of the key issue is safe ship-to-ship (STS) offloading operation for the transfer of LNG cargo to shuttle LNG carrier through marine loading arm (MLA) with side-by-side (SBS) mooring arrangement. In this paper, a numerical comparison of the side-by-side offloading operability of NS FLNG with the different mooring system is performed for the near shore site.
In order to perform the comparison, two permanent mooring types for the fixed structure (strut) mooring and spread mooring system are designed for NS FLNG. For comprehensive SBS offloading operation comparison, numerical two-body motion simulation is carried out in frequency- and time-domain. As an environmental condition, the benign sea, such as North America or East/South Asia wind, wave and current data is applied for the study.
Based on numerical simulation results, offloading operability of near shore FLNG during STS operation, dynamic loads acting on the mooring lines and fenders as well as relative motion are compared. Generally, the maximum line tension, fender force and relative motions are under the limit criteria, however, the responses of SBS line tension are not similar in both cases. Throughout the comparative study, it is found that the offloading operability of NS FLNG is affected by the different mooring system types. In addition, there are needs of further study for precise hydrodynamic analysis for damping in sloped shallow water depth.
