Experimental study of impregnated diamond bit, Part 1: Bit wear

Impregnated diamond bits are designed with segments containing multiple layers of embedded diamonds. As the outermost layer of diamonds wears out, the next layer of sharp diamonds is exposed, sustaining performance in drilling hard and abrasive formations. Although allowing diamonds to wear fully before renewal may seem optimal for bit life, industry practices often prioritize maintaining sharp diamonds. This raises a key question: which approach delivers greater efficiency? Answering this question requires a clear understanding of bit wear mechanisms, the variables governing their occurrence, and associated wear rates. Previous studies have described different wear mechanisms, but most have been qualitative and lacked methods to quantify the bit wear state and wear rate. This research addresses these gaps by: (i) developing a systematic experimental methodology to track bit wear while drilling, and (ii) conducting a comprehensive study to identify dominant wear mechanisms and quantify wear rates under various drilling conditions. With the proposed methodology, bit wear was investigated across seven rock types, five depths of cut (thickness of rock removed per bit revolution), and three angular velocities. The results led to the development of a conceptual wear model governed by depth of cut, identifying three distinct wear regimes and two critical depths of cut. Wear rates for each regime were quantified for rock types studied. The model provides a practical framework to select the optimum depth of cut based on rock properties. A sequel to this paper will explore the relationship between bit wear state and drilling response, which is defined as the relation between depth of cut and forces (axial thrust and torque) acting on the bit. • Developed a novel experimental methodology to precisely measure the wear state and the wear rate of ID bits. • The wear of ID bits is characterized by three dominant wear regimes governed by the depth of cut. • The rate of change in diamonds wear flat areas in the polishing-dominant regime increases exponentially with rock’s Mohs hardness. • For a given rock, the bit wear rate increases exponentially with the depth of cut. • The bit wear rate increases linearly with the rock’s Mohs hardness at a given depth of cut.