Drilling operation with Polycrystalline Diamond Compact (PDC) bit constitutes vertical oscillations which can both negatively and positively influence the efficiency of the penetration. In order to study the effect of bit vertical vibration in performance of PDC bits, a single PDC cutter-rock interaction, using distinct element methodology, was simulated. It has been observed that the inertia of the cutter play a significant role in vertical oscillations of the cutter. In addition, it has been found that the horizontal speed of the cutter increases the mechanical specific energy of penetration. But interaction between the cutter horizontal speed and vertical vibrations, due to imposing energized impacts on the rock-cutter interface, improves the value of MSE. However, there is an optimum level for cutter vertical vibrations to achieve an appropriate condition of penetration.
Vertical oscillations of the bit and drill string during drilling operations, which is mainly due to forces acting on PDC bit cutters, can influence the efficiency of penetration [1]. Study of a single cutter-rock interaction model can provide detail information about effect of drilling parameters such as load on cutter, cutter mass and speed, on drilling responses e.g., cutter force components, vertical vibrations, depth of cut (DOC) and amount of required energy for removing the unit volume of the rock. Teal et al. [2] named the latter mechanical specific energy (MSE). The objective of drilling industry is achieving the higher rate of penetration (ROP) with minimum MSE value. Dunayevsky et al. [4] argued that the dynamic components of the force are primarily the result of the bit-formation interaction. Also, Dubinsky et al. [5] suggested that dynamic forces, which are the result of bit and string interaction with rock, cause vibration in the bit. In addition it was argued that the drill string and bit