A downhole tool includes a blade coupled to a body. The body and blade rotate about a longitudinal axis. A pre-formed faceplate is connected to the blade and partially defines a cutter pocket therein. Another portion of the cutter pocket is defined by the blade. The cutter pocket includes a sidewall and a base, with the sidewall formed by the blade and the pre-formed faceplate, and the base formed by the blade. The pre-formed faceplate includes a pre-formed hardfacing element. A downhole tool includes a blade coupled to a body. The body and blade rotate about a longitudinal axis. A pre-formed segment is connected to the blade and has a cutter pocket therein. The cutter pocket includes a sidewall and a base, and a cutting element is coupled to the pre-formed segment and within the cutter pocket. The pre-formed segment is optionally made of a different material than the blade and has increased wear and/or erosion resistance compared to the blade.

A drill bit for cutting formation comprises a bit body, a plurality of cutters, a plurality of blades with pockets to accommodate the cutters respectively. Each of the plurality of cutters has an ultra-hard layer, two side facets extending obliquely inward from the substrate to a top surface of the ultra-hard layer, a convex portion between the two side facets. The convex portion comprises a transition surface and the transitional surface is convex as it extends between adjacent the two side facets. The curvature of the transitional surface varies along the cutter axis with the curvature at the cutting edge larger than the curvature of the cutter circumferential surface.

A drill bit for cutting formation comprises a bit body, a plurality of cutters, a plurality of blades with pockets to accommodate the cutters respectively. Each of the plurality of cutters has an ultra-hard layer, two side facets extending obliquely inward from the substrate to a top surface of the ultra-hard layer, a convex portion between the two side facets. The convex portion comprises a transition surface and the transitional surface is convex as it extends between adjacent the two side facets. The curvature of the transitional surface varies along the cutter axis with the curvature at the cutting edge larger than the curvature of the cutter circumferential surface.

A design method for a personalized drill bit for a complex difficult-to-drill formation includes: S1, acquiring rock drillability indexes of a drilled formation; S2, performing digital simulation analysis of rock breaking of bit teeth and a composite rock breaking experiment of a ring gear and a drill bit, and establishing a mechanical model of the rock interaction at the bottom of a well; S3, establishing an integrated dynamics model of drill string-drill bit-rock system coupling; S4, designing a tooth shape, a tooth distribution density, a crown shape and a gauge protection structure for rock mechanics properties of a complex difficult-to-drill formation; S5, optimizing bit nozzle and hydraulic structure parameters by using the computational fluid dynamics theory and the numerical simulation method; S6. optimizing a manufacturing process of the drill bit by using the tooth material decarburization strengthening technology, the high-strength bit body material technology and the special tooth-shaped tooth technology.

A design method for a personalized drill bit for a complex difficult-to-drill formation includes: S1, acquiring rock drillability indexes of a drilled formation; S2, performing digital simulation analysis of rock breaking of bit teeth and a composite rock breaking experiment of a ring gear and a drill bit, and establishing a mechanical model of the rock interaction at the bottom of a well; S3, establishing an integrated dynamics model of drill string-drill bit-rock system coupling; S4, designing a tooth shape, a tooth distribution density, a crown shape and a gauge protection structure for rock mechanics properties of a complex difficult-to-drill formation; S5, optimizing bit nozzle and hydraulic structure parameters by using the computational fluid dynamics theory and the numerical simulation method; S6. optimizing a manufacturing process of the drill bit by using the tooth material decarburization strengthening technology, the high-strength bit body material technology and the special tooth-shaped tooth technology.

A fixed cutting structure-composite cone drill bit includes a drill bit body, a fixed cutting structure, and at least one cone. The cone and the fixed cutting structure are disposed on the drill bit body. The cone is rotatably connected to the drill bit body by means of a bearing structure. The distance from the outermost tooth or back cone of the at least one cone to the front side surface of the fixed cutting structure La≤πR/3, and the distance from the outermost tooth or back cone of the at least one cone to the rear side surface of the fixed cutting structure Lb≤πR/3. In the composite drill bit, the distance from the cone to the front/rear side surface of the fixed cutting structure is short, the gap between the cone and the fixed cutting structure is small, transition between cutting structure is smooth.

A fixed cutting structure-composite cone drill bit includes a drill bit body, a fixed cutting structure, and at least one cone. The cone and the fixed cutting structure are disposed on the drill bit body. The cone is rotatably connected to the drill bit body by means of a bearing structure. The distance from the outermost tooth or back cone of the at least one cone to the front side surface of the fixed cutting structure La≤πR/3, and the distance from the outermost tooth or back cone of the at least one cone to the rear side surface of the fixed cutting structure Lb≤πR/3. In the composite drill bit, the distance from the cone to the front/rear side surface of the fixed cutting structure is short, the gap between the cone and the fixed cutting structure is small, transition between cutting structure is smooth.

A drill assembly (10) for use in trenchless subterranean boring, comprising: a drill shoe (20) having a body with a posterior portion (30) and an anterior portion (22), the latter defining a recess while the former comprises drill bits (32) disposed on a front end (34), opposing lateral sides, and flanks to assist the shoe (20) in acting as both pilot bore drilling tool and as reaming tool; a drill head (50) demount ably mounted to tire drill shoe (20) via tire recess and in communication with directional guidance means; a string of connectable drill rods (80), having a bailing end (82) and a leading end (84) when connected, and through which a drilling solution can be pumped towards tire drill shoe (20); a coupling (86) for linking tire leading end (84) to said drill head (50); and a connector (88) for connecting the trailing end (82) to a vehicle. The invention extends to a drill shoe (20) and a method of use and manufacture thereof.

A drill assembly (10) for use in trenchless subterranean boring, comprising: a drill shoe (20) having a body with a posterior portion (30) and an anterior portion (22), the latter defining a recess while the former comprises drill bits (32) disposed on a front end (34), opposing lateral sides, and flanks to assist the shoe (20) in acting as both pilot bore drilling tool and as reaming tool; a drill head (50) demount ably mounted to tire drill shoe (20) via tire recess and in communication with directional guidance means; a string of connectable drill rods (80), having a bailing end (82) and a leading end (84) when connected, and through which a drilling solution can be pumped towards tire drill shoe (20); a coupling (86) for linking tire leading end (84) to said drill head (50); and a connector (88) for connecting the trailing end (82) to a vehicle. The invention extends to a drill shoe (20) and a method of use and manufacture thereof.

A drill bit having a rotatable ball bit includes a first bit head and a second bit head, a first set of cutters on the first bit head, and a second set of cutters on the second bit head. The rotatable ball bit is configured to rotate between a first position and a second position, wherein the first bit head is distal to the second bit head in the first position, and wherein the second bit head is distal to the first bit head in the second position. A method of operating a rotatable ball bit includes orienting the rotatable ball bit in a first position, wherein a first bit head is oriented distally, rotating the rotatable ball bit about a longitudinal axis, orienting the rotatable ball bit in a second position, wherein a second bit head is oriented distally, and rotating the rotatable ball bit about the longitudinal axis.