INVESTIGATION OF THE OPERATING MECHANICS OF PDC DRILL BITS IN HETEROGENEOUS ROCK FORMATIONS WITH CONSIDERATION OF WEAR MECHANISMS AND VIBRATION EFFECTS

Abstract

The article examines the mechanical and dynamic features of PDC bit performance when drilling formations heterogeneous in strength and structure, with particular emphasis on the influence of vibration regimes on rock destruction stability, energy efficiency of the drilling process, and cutter wear rate. Special attention is given to the analysis of mechanisms responsible for axial, torsional, and lateral vibrations, as well as their mutual amplification when transitioning between soft and hard layers. A comparative review of mechanical-mathematical, energy-based, and empirical models describing bit–rock interaction is provided, including dependencies of penetration rate on axial load and rotational speed, criteria of specific mechanical energy of rock destruction, and methods for diagnosing unstable drilling regimes. It is demonstrated that vibrations increase energy consumption, disrupt uniform cutting, and accelerate cutter degradation through chipping, thermomechanical damage, and fatigue failure. Based on model analysis and experimental observations, engineering solutions are proposed to reduce vibrations, improve bit stability, and optimize drilling performance in complex, interbedded formations.