Axial–torsional dynamic model of a drill-string considering thermal-assisted drilling

Abstract

Thermal-assisted drilling, a recent advancement in drilling technology, aims to enhance process efficiency but its effects on drill-string dynamics remain largely unexplored. This paper presents an axial–torsional model with nonlinear bit-rock interaction coupling to investigate these effects. The first contribution is the proposition of a regularization method for a widely used nonlinear bit-rock interaction model. To validate the method, model parameters are calibrated against experimental data, demonstrating strong alignment with observed results. The second contribution is the integration of thermal effects into the bit-rock interaction, using thermal load inputs informed by previous experimental and numerical studies. Results show that under the most critical thermal load, the rate of penetration (ROP) increases by approximately 43%, highlighting the potential of thermal-assisted drilling to enhance drilling efficiency. Additionally, axial and torsional forces at the bit, along with the rotational speed of the bit, exhibit minimal variations under thermal conditions. These results indicate that thermal-assisted drilling can substantially improve ROP without compromising dynamic stability, offering new strategies for efficient and effective drilling operations.