Patent ID: 6926099
Filing Date: 2005-08-09
Classification: E21B

Abstract:
1. A bi-center bit, comprising: a bit body having a first end configured to be coupled with a drill string, a second end including a pilot section, and an eccentric reamer section intermediate the first and second ends; a first plurality of exposed cutter assemblies disposed upon an exterior surface of the pilot section; a second plurality of exposed cutter assemblies disposed upon an exterior surface of the reamer section; a plurality of recessed cutter assemblies disposed upon the exterior surface of the pilot section; wherein the recessed cutter assemblies are located within a radius beginning at a central axis of the pilot section and terminating at a central axis of the reamer section and are recessed with respect to a lower surface of the pilot section; and wherein at least one of the first plurality of exposed cutter assemblies is disposed outside of the radius and abuts the radius at the central axis of the reamer section such that the at least one of the first plurality of exposed cutter assemblies precedes the recessed cutter assemblies when the bit body is rotated around the central axis of the reamer section.