Patent ID: 7913778

Claim:
A drill bit for drilling through an earthen formation to form a borehole with a radius R, a bottom and a sidewall, the drill bit having a full gage diameter with the radius R and comprising: a bit body having a central bit axis and including a pin end, an internal plenum, and a dome side generally opposite the pin end; wherein the dome side includes a central dome region extending from the bit axis to about 10% of the radius R, an annular intermediate dome region extending from the central region to about 50% of the radius R, and an annular outer dome region extending from the intermediate region to about 90% of the radius R; a plurality of intermediate receptacles, wherein each intermediate receptacle has a central axis and extends through the intermediate dome region to the plenum; a first and a second rolling cone, each cone being mounted to the bit body and adapted for rotation about a different cone axis; wherein each cone comprises a nose proximal the bit axis, a generally planar backface distal the bit axis, an inner cone region extending axially relative to the cone axis from the nose to an intermediate cone region, and an outer cone region extending axially relative to the cone axis from the backface to the intermediate region; wherein a plurality of cutting elements are mounted to the inner region, the intermediate region, and the outer region of each cone, wherein the cutting elements mounted to the inner cone region of each cone are positioned to contact the borehole bottom between the bit axis and about 25% of the radius R, the cutting elements mounted to the intermediate cone region of each cone are positioned to contact the borehole bottom between about 25% and 75% of the radius R, and the cutting elements mounted to the outer cone region of each cone are positioned to contact the borehole bottom between about 75% and 100% of the radius R; wherein a projection of the central axis of each intermediate receptacle passes between the intermediate region of the first cone and the intermediate region of the second cone; and an intermediate nozzle disposed within each of the intermediate receptacles, wherein each intermediate nozzle has an orifice with a diameter Di; wherein the diameter Di of each intermediate nozzle is selected such that 20% to 55% of the total volumetric flow of drilling fluid through the plenum passes through the orifices of the intermediate nozzles.