Mechanical analysis of mud return on deepwater drilling riser system

The process of mud return generates complex forces on the deepwater drilling riser system. However, the specific mechanism and effect of these mud forces on the deepwater drilling riser system remain unclear. To address this gap, an analysis methodology is proposed to investigate the mechanism and effects of mud forces. Mechanical and numerical models of the deepwater drilling riser system, taking into account mud return, are established based on the analysis methodology. The mechanical model incorporates centrifugal force, Coriolis force, inertial force, and friction force. Both the individual and comprehensive effects of these mud forces are thoroughly examined. The results show that centrifugal force and Coriolis force contribute to an increase in the lateral displacement of the riser. Friction force can decrease the lateral displacement of the riser. Inertial force can change the amplitude of riser vibration. Among these forces, friction force emerges as the most significant factor. The analysis results indicate that the maximum effect of friction force is 5.15%.