The PDC cutter-rock interaction behavior in rock cutting: A review

How to increase the rock-breaking efficiency is the prerequisite for improving the rate of penetration (ROP) in drilling. At present, the roller cone bits and Polycrystalline Diamond Compact (PDC) cutter bits are widely used for breaking the rock, especially the PDC bit due to its high efficiency and longevity. The investigation of rockbreaking mechanism in cutting is essential to evaluate and design the PDC bit. Over the past decades, many researches have been devoted to investigating the rock cutting behavior, such as mechanical specific energy (MSE) for describing the rock-breaking efficiency, the ductile and brittle failure mode of rock in cutting, the influence of cutter wear on rock-breaking mechanism and the formation of dense core which reflects the energy dissipation in cutting process. All these researches, if summed up, are essential for the deep understanding of rock cutting mechanism from an overall perspective. What is more, attention has not been paid to experimental investigations on researching the rock cutting mechanism under confining pressure due to the limitation of experimental conditions. While the existence of confining pressure significantly increases the MSE, reduces the rock-breaking efficiency, and changes the failure mode and dense core formation of rock, especially in the deep formation drilling. The main objective of this paper is to provide a detailed review on the PDC cutter-rock interaction behavior with particular focus on reviewing the four aspects: MSE, ductile-brittle failure, cutting characteristic parameters and dense core theory, linking the four aspects as a whole and comprehensively considering the relationship between these four aspects and confining pressure. Obtaining an enhanced understanding of cutter-rock interaction behavior can provide the basis to address the practical issues such as low rockbreaking efficiency, high drilling string vibration and improper bottom hole assembly, and realize the purpose of improving ROP and decreasing the drilling costs eventually.