The influence of surface rocking motion on the dynamic responses of drillstring during horizontal well drilling

• A mechanical model incorporating velocity-dependent friction effect and temporal load transfer dynamics is developed to study the dynamic responses of drillstring. • The accuracy of model is validated by scaled experimental result and field data. • Parametric analyses of key factors are conducted using dynamic DWOB, toolface angle and MRD profiles. • RSM is employed to identify an optimal parameter regime. This study introduces a tribomechanical model for surface pipe-rocking drilling that integrates the velocity-dependent friction effect and temporal load transfer dynamics. The frictional velocity dependence is described by the Dieterich-Ruina model and the discontinuous rocking motion is depicted by a trapezoidal wave function. The accuracy of the model is validated through scaled experiments and field data. Parametric studies indicate that increasing rocking velocity improves the load transfer efficiency and penetration rate by damping downhole weight-on-bit fluctuations but amplifies toolface instability. Larger rocking angles enhance friction reduction through deeper maximum rocking depth, while holding time adjustments modulate toolface stability. Finally, response surface methodology is adopted for identifying an optimal parameter regime. This work provides actionable guidelines for modulating rocking parameters to balance drag reduction with toolface control.