Impregnated bit with PDC cutters in cone area

A method of forming a rotary drill bit for drilling a subterranean formation, comprising:

• forming a body having a centerline and a face extending from a centerline to a gage;
• forming a plurality of discrete, mutually separated cutting structures impregnated with a particulate abrasive material and protruding upwardly from the face, each cutting structure having a base with a larger cross sectional area than the outer most ends thereof;
• and
• forming the base of at least one of the plurality of discrete, mutually spaced cutting structures to exhibit a noncircular cross-sectional area.

A method of drilling a subterranean formation with a diamond impregnated matrix body rotary drill bit comprising:

• providing a plurality of discrete, mutually separated post-like structures on each of a plurality of blades on a face of the rotary drill bit, the plurality of discrete post-like structures containing diamond grit;
• rotating the rotary drill bit against at least a first subterranean formation under weight on bit and engaging the at least first subterranean formation with the plurality of discrete post-like structures
• wearing a portion of at least one discrete post-like structures of the plurality as it is engaged with the at least first subterranean formation such that it exposes diamond grit contained in the at least one discrete post-like structure and
• enlarging a surface area of the at least one discrete post-like structure as it wears against the at least first formation such that an increasing surface area including diamond grit is exposed.

A rotary drag bit for drilling subterranean formations, comprising:

• a bit body having a face extending from a centerline to a gage, the face including a cone portion surrounding the centerline;
• a plurality of blades on the face extending generally radially outwardly toward the gage;
• a plurality of discrete, mutually separated cutting structures comprising a particulate abrasive material protruding upwardly from each of the blades;
• and
• a plurality of polycrystalline diamond compact (PDC) cutters disposed on the face within the cone portion, wherein the discrete cutting structures are configured as posts, the posts including bases of larger cross-sectional area than outermost ends thereof and wherein the posts taper from substantially circular outermost ends to substantially oval bases.

A rotary drag bit for drilling subterranean formations, comprising:

• a bit body having a face extending from a centerline to a gage, the face including a cone portion surrounding the centerline;
• a plurality of blades on the face extending generally radially outwardly toward the gage;
• a plurality of discrete, mutually separated cutting structures comprising a particulate abrasive material protruding upwardly from each of the blades;
• and
• a plurality of polycrystalline diamond compact (PDC) cutters disposed on the face within the cone portion, wherein at least one of the plurality of discrete cutting structures is formed as a hot isostatic segment.

A rotary drag bit for drilling subterranean formations, comprising:

• a bit body having a face extending from a centerline to a gage, the face including a cone portion surrounding the centerline;
• a plurality of blades on the face extending generally radially outwardly toward the gage;
• a plurality of discrete, mutually separated cutting structures comprising a particulate abrasive material protruding upwardly from each of the blades;
• and
• a plurality of polycrystalline diamond compact (PDC) cutters disposed on the face within the cone portion, wherein the bit body comprises a matrix bit body, and the blades are integral with the bit body, the discrete cutting structures are integral with the blades and the bit body, and wherein the discrete cutting structures are comprised of a metal matrix material carrying the diamond grit and at least a portion of the blades is comprised of a softer and more abradable metal matrix material than that of the metal matrix material present in bases of the blades.

A rotary drag bit for drilling subterranean formations, comprising:

• a bit body having a face extending from a centerline to a gage, the face including a cone portion surrounding the centerline;
• a plurality of blades on the face extending generally radially outwardly toward the gage;
• a plurality of discrete, mutually separated cutting structures comprising a particulate abrasive material protruding upwardly from each of the blades;
• and
• a plurality of polycrystalline diamond compact (PDC) cutters disposed on the face within the cone portion, wherein the bit body comprises a matrix bit body, the blades are integral with the bit body, and wherein the discrete cutting structures are brazed onto the blades.

A rotary drag bit for drilling subterranean formations, comprising:

• a bit body having a face extending from a centerline to a gage, the face including a cone portion surrounding the centerline;
• a plurality of blades on the face extending generally radially outwardly toward the gage;
• a plurality of discrete, mutually separated cutting structures comprising a particulate abrasive material protruding upwardly from each of the blades;
• and
• a plurality of polycrystalline diamond compact (PDC) cutters disposed on the face within the cone portion, wherein the bit body comprises a matrix bit body, the blades are integral with the bit body, and wherein the discrete cutting structures are furnaced onto the blades.

A rotary drag bit for drilling subterranean formations, comprising:

• a bit body having a face extending from a centerline to a gage, the face including a cone portion surrounding the centerline;
• a plurality of blades on the face extending generally radially outwardly toward the gage;
• a plurality of discrete, mutually separated cutting structures comprising a particulate abrasive material protruding upwardly from each of the blades;
• and
• a plurality of polycrystalline diamond compact (PDC) cutters disposed on the face within the cone portion, wherein the PDC cutters are oriented with cutting faces substantially facing in a direction of intended bit rotation and wherein the PDC cutters include PDC sheaths contiguous with, and extending to the rear of, the cutting faces, taken in the direction of intended bit rotation, extending over substrates of the PDC cutters.