Roller cone drill bit structure having improved journal angle and journal offset

摘要

A roller cone drill bit is shown which includes at least one roller cone rotatably mounted on a journal forming a part of a bit body. The at least one cone having cutting elements disposed at selected locations thereon. The at least one roller cone subtends a journal angle of less than about 35 degrees, and has an offset less than about 0.15 inches. In one embodiment, gage row cutting elements on the at least one roller cone define an oversize angle in a range of about -1.5 to +2 degrees.