LAGRANGE equation-based dynamics analysis of deepwater drilling riser-subsea wellhead system
In order to explore the influence of large mass and stiffness blowout preventers(BOPs)on corresponding prediction accuracy of deepwater drilling riser system dynamics,this paper proposes the rigid-flexible coupling concept of riser and BOPs according to the structural characteristics of riser and BOPs,deriving the potential and kinetic energies of the riser-BOPs-subsea wellhead by the energy method.The theoretical model of the coupled system is established based on LAGRANGE,and the numerical calculation is conducted by employing the Newmark-β direct integration method based on science computation software.Taking the riser system of a deepwater well in the South China Sea as an example,the dynamic response analysis of the drilling riser based on the coupled dynamics model was carried out.The research showed that the established theoretical model and ABAQUS finite element model agreed well with each other in terms of time histories of nodes displacements and elements bending moments of three different positions along the risers,the upper and lower flex-joints rotation angles,as well as the global lateral dynamic displacement and bending moment envelopes of the deepwater risers,with the maximal error of 8.8%.This method could be used to provide references for dynamic analysis of deepwater drilling riser and subsea wellhead.
deepwater drilling risersubsea wellheadblowout preventersrigid-flexible couplingfinite element analysisdynamic analysisLAGRANGE equationnewmark-β integral method