Patent ID: 6454024
Filing Date: 2002-09-24
Classification: E21B

Abstract:
In a drill bit assembly to be lowered on a drill string into a subsurface formation, the improvement comprising:a sub connected to a lower end of said drill string; and a drill bit having a pair of blades arranged in juxtaposed relation to one another including pivotal ends mounted in said sub about a common pivot member, and blade arms extending outwardly from said pivotal ends between a position extending substantially in an axial direction downwardly from said sub and a cutting position extending substantially in a perpendicular direction with respect to the rotational axis of said drill string, said blade arms having a series of cutting elements along a cutting edge thereof; and means for imparting a centrifugal force to said blade arms to cause said blade arms to swing outwardly in a perpendicular direction with respect to the rotational axis of said drill string.