Patent ID: 9074431
Filing Date: 2015-07-07
Classification: E21B

Abstract:
1. A rolling cone drill bit for drilling a borehole in earthen formations, the bit comprising: a bit body having a bit axis; a plurality of rolling cone cutters mounted on the bit body for rotation about a cone axis; wherein each cone cutter includes a plurality of gage cutting elements mounted in a gage zone, a first plurality of bottomhole cutting elements mounted in a drive zone, and a second plurality of bottomhole cutting elements mounted in an inner zone, wherein at least some of the first plurality of bottomhole cutting elements mounted in the inner zone of one of said plurality of rolling cone cutters mesh with at least some of the first plurality of bottomhole cutting elements mounted in the inner zone of another of said plurality of rolling cone cutters; wherein the drill bit has an IADC classification selected from the group of IADC classifications between wherein the ratio of the total number of bottomhole cutter elements in the inner zone on all three cones to the total number of bottomhole cutter elements in the drive zone of all three cones is less than: