A deterministic approach to analyze the nonlinear dynamics of a horizontal drillstring
Résumé
Oil prospecting uses an equipment called drillstring to drill the soil until the reservoir level. This equipment is a long column under rotation, composed by a sequence of connected drill-pipes and auxiliary equipment. The dynamics of this columnn is very complex, because under normal operational conditions it is subjected to longitudinal, lateral and torsional vibrations, which presents a nonlinear coupling, and the structure is subjected to shocks due to the drill-bit/soil and drill-pipes/borehole impacts. This work presents a deterministic computational model to analyze a drillstring with horizontal configuration. This model uses a nonlinear beam theory which takes into account the rotatory inertia and shear deformation of the beam cross section, as well as the coupling between longitudinal, transverse and torsional vibrations. The nonlinear model equations are discretized using the finite element method, and a reduced model is obtained by projecting the system dynamics into the space spanned by the linear modes associated to the dynamical system. Numerical simulations are conducted and analyzed.