Influence Of Sloping-Seabed And Transient Tidal Current On Single Mooring Systems

Single Position Mooring system has been attempted worldwide because of cost effectiveness and good weathervane effect. With the change of the ocean environment and the expansion of exploration areas, new problems spring up in the process of application of SPM in marine oil and gas exploration field. More factors should be considered in the mooring system design.Based on the mooring line and floating body coupled dynamic analysis theory, the motion and force responses of SPM are investigated. The influences of seabed slope angle and transient tidal current on SPM motion performance are studied.First, the static configuration of mooring line considered arbitrary seabed shape is obtained. The effects of sloping-seabed on a single mooring line tension and turret FPSO system are investigated. The result shows that the drift frequency motion is the main reason affecting the cable tension. And when the seabed slope angle is small, the motion and maximum cable tension change insignificantly. The value should not be ignored when the angle is large.In order to investigate the large rotation problem of SPM in transient tidal current, the transient current force is calculated based on the second development of hydrodynamic software AWQA. A24hour-time motion of a single yoke system is simulated. The result shows the FPSO experiences the large rotation motion with the rapid small amplitude rotation This small angle rotation process has a large proportion of the total rotary angle, and the value is accurately calculated based on numerical simulation method in this paper. This method is more accurate to analyze the wear performance in the engineering fields.