Downhole Tool with Fixed Cutters for Removing Rock

A downhole tool to be rotated for cutting rock to form a borehole comprising:

• a body having a cutting face and a center axis about which the downhole tool rotates;
• plurality of blades on the cutting face;
• a plurality of channels separating the plurality of blades, each of the plurality blades having a front wall adjacent to one of the plurality of channels and a back wall adjacent to another of the plurality of channels;
• wherein each of the plurality of blades has arranged along a leading edge of the blade a plurality of cutters in fixed positions;
• wherein at least one of the plurality of blades is an offset blade, the offset blade comprising at least two portions, the at least two portions comprising a first blade portion and a second blade portion;
• the leading edge of the offset blade comprising a first leading edge portion and a second leading edge portion corresponding to the first and second blade portions, the second leading edge portion of the leading edge of the offset blade being angularly offset from the first leading edge portion to form a step along the leading edge;
• and
• wherein the downhole tool further comprises,
• a first nozzle that is located within the channel adjacent the front side of the offset blade and is positioned and oriented to direct a circulation medium toward the plurality of cutters on the first leading edge portion;
• and
• a second nozzle within the channel that is adjacent to the front wall of the offset blade, the second nozzle being located displaced angularly and radially from the first nozzle and oriented to direct the circulation medium toward the plurality of cutters on the second leading edge portion.

A rotary drag bit for cutting rock to advance borehole comprising:

• a body having a cutting face and a center axis about which the bit rotates, the cutting face having a cone region, a nose region, and shoulder region and a gauge;
• plurality of elongated blades on the cutting face extending radially outwardly, at least one of the plurality of elongated blades being a primary blade extending from nearing the center axis;
• a plurality of channels separating the plurality of elongated blades, each of the plurality of elongated blades having a front wall adjacent to one of the plurality of channels and a back wall adjacent to another of the plurality of channels;
• and
• a plurality of primary cutters mounted in fixed positions along a leading edge of each the plurality of elongated blades, the plurality of primary cutters defining primary cutting profile for the bit, each of cutters having a radial position with the primary cutting profile, a radial position on one of the plurality of elongated blades, and an orientation;
• wherein the primary blade is an offset blade, the offset blade comprising at least two portions, the at least two portions comprising a first blade portion and a second blade portion;
• the leading edge of the offset blade comprising a first leading edge portion and a second leading edge portion corresponding to the first and second blade portions of the offset blade, the second leading edge portion of the leading edge of the offset blade being angularly offset from the first leading edge portion to form a step without forming an opening in the offset blade extending between the front wall and rear wall of the offset blade;
• wherein the offset blade further comprises a top surface from which the plurality of primary cutters extend, the back wall has a top edge that, along at least a portion of the front wall, is lower than the top surface, and, the offset blade comprises a sloped back surface extending from the top surface to the lower top edge portion of the back wall;
• and