Research of rigid-flexible coupling dynamics model for riser-LMRP/ BOPs-wellhead system

The deepwater drilling riser system is the most vulnerable part of the offshore drilling operation. Understanding its dynamic response under complex marine environment is crucial for ensuring drilling safety. However, the coupling mechanism between the riser and LMRP/BOPs is not well understood in existing analysis models of riser system dynamic response. In this paper, a theoretical model for the rigid-flexible coupling dynamics of multi-scale riser-LMRP/BOPs-wellhead system is proposed to reveal the coupling mechanism between the riser and LMRP/BOPs. Considering the characteristics of flexible riser and rigid LMRP/BOPs as well as the nonlinear coupling effect between conductors and soil, a rigid-flexible coupling dynamics model of the riser-LMRP/BOPs-wellhead system is established based on the theory of rigid-flexible coupling dynamics and Lagrange equation, which is numerically solved by the Newmark method. To verify the correctness of the proposed model, a simulation model of the riser-LMRP/BOPs-wellhead system is applied, which is modelled by the combination of pipe and mass elements. The research results demonstrate that the numerical results of the proposed theoretical model agree with the simulation results of the coupling system, thus verifying the correctness of the proposed model and revealing the rigid-flexible coupling mechanism between the riser and LMRP/BOPs.