Abstract
The study analyzes the nonlinear dynamics of shallow drill strings under seismic activity in a geological environment. The main objective is to determine the impact of seismic wave influence on the oscillatory process by identifying the dynamic response to types and intensities of seismic excitation, considering the presence of finite deformations. Based on Hamilton principle, a nonlinear mathematical model for the spatial motion of the drill string was developed. A key point was the inclusion of seismic effects in the kinetic energy of the system, which is achieved by accounting for the displacement of the wellbore relative to the global coordinate system. This methodological approach provided description of the influence of dynamic ground mass displacements on the inertial parameters of the system. The research results indicate the transition of the drill string to quasi-periodic oscillation modes, which increase the unpredictability of its dynamics, the risks of resonant vibrations.