A nonlinear mechanical model for deepwater steel lazy-wave riser transfer process during installation

•A mechanical model for deepwater SLWR transfer process is proposed.•The system comprising A&R cable, vessel, pull-in cable and platform is considered.•Numerical analysis of a typical transfer process is carried out comprehensively.•The proposed model can be help on design and dynamic analysis of SLWR installation.

To meet the increasing applications of the deepwater steel lazy-wave riser (SLWR), its installation is a great challenge for SLWR which affects its service performance. This paper is focused on the transfer process during the SLWR installation which is of great importance to the installation feasibility and analysis. A comprehensive mechanical model based on the nonlinear large deflection beam theory for the deepwater SLWR transfer process is developed. The presented model is able to deal with three different stages analysis of the transfer process and the length and tension of the two cables used to lift the riser's pull-head: A&R cables of installation vessel and pull-in cable of production platform. Numerical analysis is conducted to investigate the riser configurations and some important mechanical parameters which exert influences on the riser's performance. The proposed model can be a basic reference to the design and dynamic analysis of deepwater SLWR installation.