Nonlinear Dynamics of a Rotary Drill-String Immersed in a 3D Geometry Well

Oil or geothermic rotary drilling is composed with a very slenderness drill-string which is subjected in particular to the tool-bit excitations. Therefore a great number of vibratory phenomena concerned with the axial, lateral and torsional behavior are exhibited: whirling, bit bouncing, stick slip to cite just a few. In order to predict the rotordynamics of such a structure, the model proposed is based on Timoshenko beam elements immersed in a 3D geometry well. A constant rotation speed in imposed at the top of drill-string. A fluid-structure interaction model that takes into account the drilling mud is used. The effect of drilling mud in drill-string vibration is studied by varying the well trajectories.