Research on the Effect of Combined Cutters of PDC Bit on Cutting Efficiency

Polycrystalline diamond compact (PDC) bits have changed the way to cut rock comparing to the roller cone bits, occupying a large market in oil and gas drilling. PDC cutter is made of diamond layer and tungsten carbide. With the continuous improvement of PDC cutter processing technology, the non-plane (special-shaped) structures of PDC layer have been realized. Many special-shaped cutters adapted to different formations were invented. In order to broaden the application range of these special-shaped cutters, a series of combination of multiple PDC cutters should be studied. As an extension of single cutter testing, multiple PDC cutters testing is closer to the PDC bit drilling in the field. In this paper, to explore the effect of multiple PDC cutters, the numerical simulation software LS-DYNA was used to simulate the rock breaking modes of different combinations of special-shaped cutters and traditional plane cutters. The numerical simulation results show that the combination of special-shaped cutter and traditional plane cutters has obtained higher cutting efficiency. The profile of special-shaped cutter’s cutting track is more conducive to the improvement of the efficiency of the adjacent cutters. With the increase depth of cutting (DOC), the cutting efficiency increases gradually. At the same time, the optimal cutter spacing increases with the increase of DOC. The research results show that the cutting efficiency can be improved by the combination cutting mode of special-shaped cutter and cylinder-shaped cutter (CSC), which provides an important theoretical support for personalized bit design in difficult formations.