Development of a Whirl-Resistant Bit

Summary Bit whirl is a major cause of early failure and reduced performance of polycrystalline-diamond-compact (PDC) bits. Attempts to control bit whirl by stabilizing the drillstring have been unsuccessful, but a "low-friction" bit design has been discovered that substantially eliminates whirl. The low-friction design is based on placing the cutters so that the net imbalance force from the cutters is directed toward a smooth pad that slides along the wellbore wall.