Optimization of mooring line design parameters using Mooring Optimization Tool for FPSO (MooOpT4FPSO) with the consideration of integrated design methodology

Optimization of mooring line design parameters including line azimuth angles, line diameter, line length and mooring radius is presented for a turret-moored FPSO. The optimization procedure is implemented using a Mooring Optimization Tool for FPSO (MooOpT4FPSO), which is an in-house optimization tool purposely developed for this purpose. The tool is a synchronisation of the Regrouping Particle Swarm Optimization (RegPSO) algorithm with commercial software, OrcaFlex. Case studies using a validated numerical FPSO model moored with multicomponent mooring lines acted upon by non-collinear wave, wind and current were analysed using the developed tool. To take into consideration the interaction of the riser system in the optimization procedure, the integrated design methodology was adopted where the riser safe operation (SAFOP) zone diagram combined with the offset diagram is used for the verification/assessment of the design criteria of the risers and mooring lines. The optimized FPSO model offsets in eight directions are found to be within the riser safe operation zone. Based on the results, the tool was able to simultaneously optimise the mooring line diameter, line length, mooring radius, and azimuth angles of the turret FPSO to achieve a specific offset. Application of the tool can help the industry save material (by reduction of line diameter and length) and consequently the overall project cost, in addition to the reduction of structural payload exerted on the platform. Furthermore, the tool has an automatic search capability, which is an improvement to the conventional mooring design approach that is based on a trial-and-error approach. •A novel numerical optimization tool for FPSO mooring line parameters for (MooOpT4FPSO) have been developed.The tool has the capability of simultaneously optimizing azimuth angles, line lenght, line diameter and mooring radius of turret FPSO.•Application of the tool in mooring design can bring a reduction in line material and consequently the overall project cost, in addition to the reduction of payload exerted on the platform.•Application of the tool brings a direct industrial solution to the conventional trial and error approach.