A rock bit for blast hole drilling includes: a bit body having a coupling formed at an upper end thereof, a plurality of lower legs, a dome formed between the legs, and a bore formed through the coupling and the dome; a plurality of skirts, each skirt covering a gap formed between adjacent legs and each skirt mounted to edges of adjacent legs; a plurality of roller cones, each rotary cone rotatably mounted to a respective bearing shaft of a respective leg; a row of gage cutters mounted to each roller cone; a row of inner cutters mounted to each roller cone; one or more nose cutters mounted to each roller cone; and a center jet secured in the bore. Each cutter is an insert.

A rock bit for blast hole drilling includes: a bit body having a coupling formed at an upper end thereof, a plurality of lower legs, a dome formed between the legs, and a bore formed through the coupling and the dome; a plurality of skirts, each skirt covering a gap formed between adjacent legs and each skirt mounted to edges of adjacent legs; a plurality of roller cones, each rotary cone rotatably mounted to a respective bearing shaft of a respective leg; a row of gage cutters mounted to each roller cone; a row of inner cutters mounted to each roller cone; one or more nose cutters mounted to each roller cone; and a center jet secured in the bore. Each cutter is an insert.

A wellbore drill bit assembly includes a drill bit that includes a drilling fluid pathway that has an inlet fluidly connected to a drilling fluid entrance of the drill bit and an outlet fluidly connected to a drilling fluid exit of the drill bit; and a nozzle positioned in the drilling fluid pathway, where at least a portion of the nozzle includes a removable material configured to dissolve or erode in contact with a drilling fluid additive.

A wellbore drill bit assembly includes a drill bit that includes a drilling fluid pathway that has an inlet fluidly connected to a drilling fluid entrance of the drill bit and an outlet fluidly connected to a drilling fluid exit of the drill bit; and a nozzle positioned in the drilling fluid pathway, where at least a portion of the nozzle includes a removable material configured to dissolve or erode in contact with a drilling fluid additive.

The disclosed drill tools have metal matrix composite (MMC) or steel alloy bodies that are formed around one or more pre-fabricated components using either a casting or infiltration process. The pre-fabricated components are made of sintered, infiltrated, and/or cemented particles of an ultrahard material, and may form any suitable portion of the bit blades. The pre-fabricated components may be loaded into a machined mold, and the mold cavity is subsequently filled with powder, such as tungsten carbide powder, filler metal powder, binder metal powder, or combinations thereof. During a casting or infiltration process, the mold and pre-fabricated components are heated to a sufficient temperature to melt the binder metal and/or filler metal, wherein the molten metal superficially interacts with the inner surfaces of the pre-fabricated components to form a metallurgical bond to secure the pre-fabricated components to the bit body.

This disclosure presents a downhole device configured as a selectable hole trimmer. The selectable hole trimmer comprises an upper sleeve affixed inside a body via a stop. A charge sleeve is slidable inside the upper sleeve to provide a pressure to a pressurized volume. A catch sleeve is slidable inside the charge sleeve to align a bypass port and a return port with a drilling mud volume. An actuator is fluidly connected to the pressurized volume via a port. The actuator is configured to provide a pressure to a selectable hole cutter of the body via an actuation port in the transfer sleeve and actuate the selectable hole cutter piston of the selectable hole cutter to move relative to the body, wherein the cutter piston comprises one or more cutters. A manual controller configured to operate the actuator in response to a dropped activation ball.

This disclosure presents a downhole device configured as a selectable hole trimmer. The selectable hole trimmer comprises an upper sleeve affixed inside a body via a stop. A charge sleeve is slidable inside the upper sleeve to provide a pressure to a pressurized volume. A catch sleeve is slidable inside the charge sleeve to align a bypass port and a return port with a drilling mud volume. An actuator is fluidly connected to the pressurized volume via a port. The actuator is configured to provide a pressure to a selectable hole cutter of the body via an actuation port in the transfer sleeve and actuate the selectable hole cutter piston of the selectable hole cutter to move relative to the body, wherein the cutter piston comprises one or more cutters. A manual controller configured to operate the actuator in response to a dropped activation ball.

A drill head including: an elongate housing, a first end of the housing being coupled to an end of a drill pipe in use; a base at a second end of the housing, one or more drill cutters being attached to the base; a supply passageway at least partially within the housing, the supply passageway being supplied with a flow of gas in use; a return passageway at least partially within the housing, a first end of the return passageway being connected to an end of an inner tube extending inside the drill pipe in use, and a second end of the return passageway forming an opening in the base proximate to the one or more drill cutters; and one or more ports for directing at least some of the flow of gas from the supply passageway into the return passageway in a flow direction extending away from the base and towards the inner tube, to thereby cause loose material to be drawn into the return passageway through the opening and transported away from the drill head via the inner tube in use.

An earth-boring bit includes a bit body threaded at its upper extent for connection to a drill string and a plurality of blades on the bit body, each blade having a leading edge and a trailing edge. A plurality of cutting elements is arranged on the leading edge of each blade and a junk slot is defined between pairs of adjacent blades. A surface texture may be formed on the surface of the junk slot, the surface texture being selected to alter a flow of drilling fluid through the junk slot. At least one milling element may extend at least partially across the junk slot between the trailing edge and leading edge of adjacent blades, wherein flow of cuttings generated by the cutting elements is impeded until the cuttings are disintegrated to a selected size.

An earth-boring bit includes a bit body threaded at its upper extent for connection to a drill string and a plurality of blades on the bit body, each blade having a leading edge and a trailing edge. A plurality of cutting elements is arranged on the leading edge of each blade and a junk slot is defined between pairs of adjacent blades. A surface texture may be formed on the surface of the junk slot, the surface texture being selected to alter a flow of drilling fluid through the junk slot. At least one milling element may extend at least partially across the junk slot between the trailing edge and leading edge of adjacent blades, wherein flow of cuttings generated by the cutting elements is impeded until the cuttings are disintegrated to a selected size.