Modeling, validation and parametric analysis of the axial dynamics of a vibration-assisted drilling tool

Abstract

The purposes of this work are: to develop a mathematical model that represents the axial dynamics of a vibration-assisted drilling tool, to validate the proposed mathematical model with field data, and to analyze the axial nonlinear dynamics of a vibro-impact system used as a drilling tool. A lumped-parameter vibro-impact model is presented to describe the axial dynamics of a prototype vibration-assisted drilling tool developed to improve the drilling efficiency in hard-rock formations. The proposed model has seven degrees of freedom with four impact surfaces. Field data from high-frequency acquisition, measured at multiple locations, is used to validate the mathematical model. A parametric analysis investigates the effect that some design parameters have on the dynamic behavior of the system. Furthermore, a measure is proposed to evaluate the efficiency of the process, and used for design modifications of the current vibro-impact system. The results show an overall reasonable match between field data and model outputs because the vibro-impact model is capable of reproducing the main dynamic behavior of the vibrationassisted drilling tool. Furthermore, the proposed model is able to reproduce complex dynamic behavior with little computational cost due to the small number of degrees of freedom. The results from the parametric analysis reveal the possibility of 85% increase in the impact force transfer and 125% increase in the mud flow operating range, when compared with the original design.