Abstract
Drilling is one of the most expensive processes in the oil and gas exploration and exploitation processes which is commonly performed with polycrystalline diamond compact (PDC) fixed-cutter bits (or PDC bits as they are often referred to) due to their good stability and high flexibility in design. The PDC bit longevity strongly depends on the wear flat surface that changes during progression through rock materials. The wear flat size increases with time and can greatly influences the bit performance and efficiency. The increase in wear causes increasing weight-on-bit (WOB) on the PDC bit to keep the rate of penetration (ROP) constant. Over the past decades, contrary to the pure cutting process, not many investigations have been devoted to studying the friction mechanism at the wear flat-rock interface, resulting in poor understanding of the friction mechanism. The objective of this paper is to provide a detailed review of the state-of-the-art in rock cutting with particular focus on the frictional mechanism of the blunt PDC cutters and issues associated with the contact stress and the friction coefficient at the wear flat-rock interface. Moreover, the contact forces at the wear flat are governed by the wear flat inclination angle. Gaining a better understanding of the frictional contact process can eventually play a significant role in addressing practical issues such as drilling efficiency, optimization, and susceptibility to vibrations. Further, in spite of some obvious differences between the indentation and rock cutting processes, the main similarities between these two processes are also discussed which can provide new insights for the further studies.
NSTL