Study on the acceleration of single‐cone PDC composite bit

Abstract

The single‐cone bit has become the first choice for slim hole sidetracking and deep well drilling with its unique rock breaking method and high ROP (rate of penetration). The single‐cone bits currently used in the oil field all use cemented carbide inserts, with its main failure mode being of early excessive wear of the cutting teeth. In order to improve the adaptability of single‐cone bits to hard and highly abrasive formations, a single‐cone PDC composite bit is designed. According to the characteristics of the tooth profile, the way of tooth arrangement and the way of contact between the cutting teeth and the rock, the acceleration equation to the cutting teeth of the single‐cone PDC composite bit is established. The shaft inclination angle of the cone, the position and height of the PDC teeth, the radius of the PDC teeth, the lateral rotation angle, and the front inclination angle on the acceleration are studied. The acceleration of the single‐cone bit is verified by numerical simulation and drilling experiment of rock‐breaking. Rock formation properties have an impact on the acceleration of the cutting teeth, with the acceleration of the cutting teeth in hard rock formations being higher than that in soft rock formations. On the premise that the bearing life of the single‐cone bit is allowed, the value of the shaft inclination angle β can be approached to 70°. This research lays a theoretical foundation for the dynamic research and wear analysis of single‐cone PDC composite bit.