Abstract: A rotary drag bit equipped with a plurality of cutters, each including a superabrasive cutting face, wherein cutters carried by the bit have at least two differing chamfer geometries adjacent their cutting edges. Chamfer geometries are selected according to location on the face of the bit responsive to the relative ease or difficulty of cutting formation rock and the severity of dynamic loading at that location. The bit face may be characterized as comprising at least two areas or regions bearing cutters having differing chamfer geometries to maximize rate of penetration of the bit while preserving cutter integrity when subjected to differing stresses and encountering zones of the formation exhibiting different strengths. Characteristics, such as hardness, abrasiveness and homogeneity, of the target formation or formations to be drilled by the bit may be considered when selecting appropriate chamfer geometries for the cutters allocated to cut each formation zone opposite the bit face.

Abstract: A drilling apparatus having cuttings removal structure to reduce balling thereof and to help prevent the accretion of portions of chips and debris from drilling thereon and/or the accretion of portions of drilling fluids thereon. The drilling apparatus comprises an apparatus body having a connection thereon and structure for contacting cut portions of the earth formation. The contacting structure may include chip breakers and flails or combinations thereof.

Abstract: Superabrasive cutting elements for use in drilling subterranean formations, and drill bits so equipped. The cutting element includes a superabrasive table between about 0.090 inch and 0.120 inch thickness, mounted to a supporting cemented carbide substrate. The superabrasive table includes a two-dimensional cutting face with a first surface transverse to the longitudinal axis of the cutter and a second, planar engagement surface or buttress plane oriented at a small, acute angle with respect to the first surface and having a cutting edge along at least a portion of its periphery adjacent the lateral periphery of the cutter. A tapered side surface on the superabrasive table to the rear of the cutting edge flares outwardly, terminating in a side surface parallel to the cutter axis, continuing to the supporting substrate.

Abstract: This invention discloses a drilling structure having a body defining at least one primary channel and at least one secondary channel therein to initiate and maintain recirculation of an amount of drilling fluid back through the secondary channel to maintain positive, independent flow of drilling fluid through each primary channel of the drilling structure. The recirculation of drilling fluid is encouraged by providing a recirculation passageway in fluid communication with the primary channel defined by a portion of the body of the drilling structure that separates positively flowing drilling mud from drilling mud that is being recirculated. The recirculation action of the fluid in the recirculating loop may be fed and brought about by entrainment of the fluid with jetted fluid from an adjacent nozzle.

Abstract: This invention discloses a drilling structure having body a defining at least one primary channel and at least one secondary channel therein to initiate and maintain recirculation of an amount of drilling fluid back through the secondary channel to maintain positive, independent flow of drilling fluid through each primary channel of the drilling structure. The recirculation of drilling fluid is encouraged by providing a recirculation passageway in fluid communication with the primary channel defined by a portion of the body of the drilling structure that separates positively flowing drilling mud from drilling mud that is being recirculated. The recirculation action of the fluid in the recirculating loop may be fed and brought about by entrainment of the fluid with jetted fluid from an adjacent nozzle.

Abstract: A drilling apparatus having cuttings removal structure to reduce balling thereof comprising an apparatus body having a connection thereon, and structure for contacting cut potions of the earth formation. The contacting structure may include chip breakers, flexible cables, rotating nozzle assemblies, rotating turbine wheel assemblies, rotating vane assemblies, flails or combinations of these. The apparatus may include elastomeric portions and/or movable potions. The drilling apparatus may comprise a drill bit, drilling stabilizer, drill collar, reamer, downhole motor, etc.

Abstract: A cutting element for a rotary drill bit for subterranean drilling, including a substantially planar table of superhard material having a cutting face and a cutting edge. The table may be reinforced against bending with one or more strut portions extending from the rear of the table to the rear of the substrate and at least partially across the cutting element. The strut portions may be integral with the diamond table, or separately fabricated and of another material. The strut portions, in addition to or in lieu of providing stiffness to the superhard table, may also serve to enhance heat transfer away from the cutting face and cutting edge of the superhard table. The structure supporting the cutting element on the drill bit and the body of the drill bit itself may be additionally configured to include structures to facilitate heat transfer away from the superhard table.

Abstract: A rotary drag bit for drilling hard rock formations with substantially planar PDC cutting elements having diamond tables backed by substrates which flare or taper laterally outwardly and rearwardly of the cutting edge of the diamond table. A cutting structure defining a "lipped" cutting edge is also disclosed.

Abstract: A diamond cutting element including a substantially planar diamond table having a periphery defined by a multiple chamfer. The angle of the outermost chamfer may be oriented to provide a bearing surface on the cutting element at the place of engagement with the formation being drilled.

Abstract: An improved stud design for an earth boring drill bit is disclosed preferably using materials of different hardness and toughness layered to provide maximum resistance to surface abrasion coupled with excellent structural properties including high strength with maximum fracture toughness. The bit body is conventionally attached to a drill string, and has a crown and gage portion. The studs preferably include a core, made of steel or other material having high fracture toughness, covered at least in part with a hard, abrasion resistant material such as tungsten carbide. Each stud is secured to a socket in the bit body by means of brazing or other suitable means such as a press fit. The cutting element is brazed to a mounting face of the stud prior to affixation of the stud to the bit body and is preferably comprised of a polycrystalline diamond compact adhered to a backing layer of tungsten carbide.

Abstract: A drill bit and method in which polycrystalline diamond cutters mounted on a bit crown cut formation chips akin to the manner in which a grater cuts cheese. Chips in impermeable or plastic formations are extruded by the cutters into cavities internal to the bit via slots adjacent each cutter. Drilling fluid circulates internally of the bit from the drill string and into the annulus above that portion of the bit bearing cutters. In one embodiment, the portion of the bit body upon which the crown is formed is made of an elastomer which is pressurized into sealing engagement with the bottom of the borehole thereby further sealing freshly cut formation from drilling fluid.

Abstract: A rotary drill bit is provided for boring earth formations which includes a bit blank and a metal matrix secured to the blank. The metal matrix includes a filler material dispersed therein. Cutting elements are mounted on the exterior face of the bit, and substantially all of the exposed internal and external surfaces of the bit are coated with an erosion and abrasion resistant hardfacing material bonded to the metal matrix.