Coupling time-domain analysis for pipeline end termination installation based on pipelaying

Abstract

To study the dynamic characteristics of the pipeline end termination (PLET) installation operation based on pipelaying under full coupling effect, a numerical model for PLET installation based on S-laying with the vessel–cable–PLET–pipeline coupling in time domain is proposed in this study. The whole model mainly consists of four parts, which are the pipelaying vessel, the abandonment and recovery (A&R) cable, the pipeline and the PLET. The finite element method is proposed for the pipeline and the cable, while the hydrodynamic forces on the PLET are simulated by the Morison equation. The pipelaying vessel is controlled by a dynamic positioning system. The proposed model is validated by OrcaFlex software and then used to carry out numerical simulations of PLET installation based on practical operations. The static and dynamic responses of each part in different operation phases and under different wave and current directions are analyzed. The results show that the PLET position in different phases as well as the direction of wave and current during installation has great effect on forces and motions of the system parts. Moreover, the dynamic responses of different parts are apparently connected, so the coupling effect cannot be ignored.