Patent ID: 7407012

Claim:
A drill bit comprising: a bit body; at least one roller cone rotably attached to the bit body; and a plurality of cutting elements disposed on the at least one roller cone in a plurality of rows arranged circumferentially around the at least one roller cone, the plurality of rows comprising: at least one inner row; a gage row; and a heel row; wherein at least one cutting element in the gage row, the heel row, or a surface of the at least one roller cone bounded by the gage and heel rows is a thermally stable polycrystalline diamond cutting element comprising: a carbide substrate; and a thermally stable polycrystalline diamond top portion disposed on the carbide substrate; wherein carbide substrate has a greater volume than the thermally stable polycrystalline diamond top portion; and at least one cutting element in the at least one inner row comprises at least one of a milled tooth and a tungsten carbide insert, consisting of cemented tungsten carbide.