Dynamic Behavior of a DICAS FPSO and Shuttle Vessel under the Action ofWind, Current and Waves

摘要

Floating, Production, Storage and Offloading (FPSO) systems consistrnof a large tanker moored to the seabed operating as an offshorernproduction facility. During the offloading operation, another tanker (thernshuttle vessel) is attached to the FPSO through a flexible hawser tornallow the safe connection of a hose for cargo transfer. In previousrnworks we have applied a nonlinear dynamical systems approach torninvestigate the behavior of these systems under the action of wind andrncurrent. Both Differentiated Compliant Anchoring System DICAS andrnturret FPSO mooring arrangements were considered. For the presentrnstudy we have taken a DICAS system, and performed a numericalrninvestigation of the influence of the action of sea waves in addition tornwind and current. Suitable spectra were employed, and second-orderrneffects such as slow drift forces, as well as wave-current interactionrncorrections to mean drift forces, namely wave drift damping, wererncalculated. The predicted dynamics for the system were calculated forrnrelevant ranges of environmental parameters such as wind and currentrnspeeds, wave spectra, and respective angles of incidence. The influencernof the draft of the vessels was also inspected. Results were summarizedrnin bifurcation diagrams displaying the evolution of steady-staternresponses as a function of parameters characterizing the environmentalrnstate. The stability of steady-state responses was investigated usingrntime-domain simulations. The results were also employed to illustraternthe production of diagrams in which inadequate (or unacceptable)rndynamic solutions are identified.