Patent ID: 7703557

Claim:
A drill bit for drilling a borehole in earthen formations, the bit comprising: a bit body having a bit axis and a bit face including a cone region, a shoulder region, and a gage region; a primary blade extending radially along the bit face from the cone region through the shoulder region to the gage region; a plurality of primary cutter elements mounted to the primary blade; at least one backup cutter element mounted to the primary blade in the shoulder region; a secondary blade extending along the bit face from the shoulder region to the gage region; a plurality of primary cutter elements mounted to the secondary blade; wherein the secondary blade is free of backup cutter elements; wherein each backup cutter element and each primary cutter element has a radial position; wherein each backup cutter element mounted to the primary blade is disposed at substantially the same radial position as one of the plurality of primary cutter elements mounted to the primary blade; wherein each primary cutter element includes a primary cutting face and wherein each backup cutter element includes a backup cutting face, wherein each primary cutting face and each backup cutting faces is forward-facing; wherein the plurality of primary cutter elements mounted to the primary blade are arranged in a row extending radially from the cone region to the gage region, and the plurality of primary cutter elements mounted to the secondary blade are arranged in a row extending radially from the shoulder region to the gage region; and wherein the cone region is free of backup cutter elements.