Numerical simulation and experimental study of rock-breaking with full single-roller PDC compound bit

Abstract ‘Background:’ The single cone bit holds a significant position in small hole drilling, but its lifespan and rock-breaking efficiency in deep, ultra-deep, and small hole drilling need improvement. To address this, a spherical single-roller PDC composite bit was designed, combining the advantages of single cone bits and PDC cutters to enhance performance in hard rock formations. ‘Method of approach:’ Numerical Simulation: A full-tooth rock-breaking numerical model was established to simulate the dynamic cutting process of the single-roller PDC composite bit in rock, analyzing the distribution of cutting forces and rock-breaking patterns. experimental Validation: A full-size single-roller PDC composite bit was manufactured, and indoor rock-breaking experiments were conducted. ‘ Results: The cutting forces of the seven PDC cutters showed periodic distribution, with peak forces appearing alternately. The alternating slip-scraping rock-breaking mode effectively utilized the shear advantages of PDC cutters, reducing repeated rock fragmentation. Experimental Results: Rock-Breaking Efficiency:In hard limestone, the rate of penetration (ROP) of the new bit increased by 170%-290% compared to the traditional bit.In sandstone, the ROP increased by 68%-782%. Energy Efficiency:The MSE of the new bit was less than 44% of the traditional bit.At higher WOB, the new bit demonstrated lower energy consumption and higher efficiency. ‘Conclusions:’ Performance Advantages: The single-roller PDC composite bit significantly improves rock-breaking efficiency and reduces energy consumption in hard rock formations, particularly in deep and ultra-deep wells.