A reversible polycrystalline diamond compact (PDC) bit. The reversible PDC bit includes at least one blade, at least one front cutter disposed on a first side of the at least one blade, and at least one rear cutter disposed on a second side of the at least one blade, wherein the first side is opposite to the second side along a circumferential direction of the reversible PDC bit, wherein rotating the reversible PDC bit in a clockwise direction engages the at least one front cutter to cut into a subterranean formation, and wherein rotating the reversible PDC bit in a counter-clockwise direction engages the at least one rear cutter to cut into the subterranean formation.

A reversible polycrystalline diamond compact (PDC) bit. The reversible PDC bit includes at least one blade, at least one front cutter disposed on a first side of the at least one blade, and at least one rear cutter disposed on a second side of the at least one blade, wherein the first side is opposite to the second side along a circumferential direction of the reversible PDC bit, wherein rotating the reversible PDC bit in a clockwise direction engages the at least one front cutter to cut into a subterranean formation, and wherein rotating the reversible PDC bit in a counter-clockwise direction engages the at least one rear cutter to cut into the subterranean formation.

A tunnel boring machine including a propulsion system, an enclosure carried by the propulsion system, and a torch support structure carried by the enclosure. The torch support structure can include a primary disc mounted on a rotatable shaft carried by the enclosure, a first plurality of plasma torches mounted to the primary disc, and a power supply cable coupled to the enclosure and adapted to supply power to the boring machine from one or more power sources.

A tunnel boring machine including a propulsion system, an enclosure carried by the propulsion system, and a torch support structure carried by the enclosure. The torch support structure can include a primary disc mounted on a rotatable shaft carried by the enclosure, a first plurality of plasma torches mounted to the primary disc, and a power supply cable coupled to the enclosure and adapted to supply power to the boring machine from one or more power sources.

A downhole drilling motor assembly includes a first motor, a second motor aligned coaxially with the first motor, and a clutch assembly aligned coaxially with the first and second motors. The clutch assembly independently and selectively actuates each of the first and second motors to rotationally drive a drill bit. A related method includes: mounting a drill bit at a distal end of a drill string at a well site; and providing a downhole drilling motor assembly which rotationally drives the drill bit. The clutch assembly is controlled to independently and selectively actuate the first and second motors, and the drill bit is rotationally driven via the independent and selective actuation of the first and second motors.

A downhole drilling motor assembly includes a first motor, a second motor aligned coaxially with the first motor, and a clutch assembly aligned coaxially with the first and second motors. The clutch assembly independently and selectively actuates each of the first and second motors to rotationally drive a drill bit. A related method includes: mounting a drill bit at a distal end of a drill string at a well site; and providing a downhole drilling motor assembly which rotationally drives the drill bit. The clutch assembly is controlled to independently and selectively actuate the first and second motors, and the drill bit is rotationally driven via the independent and selective actuation of the first and second motors.

A reversible polycrystalline diamond compact (PDC) bit. The reversible PDC bit includes at least one blade, at least one front cutter disposed on a first side of the at least one blade, and at least one rear cutter disposed on a second side of the at least one blade, wherein the first side is opposite to the second side along a circumferential direction of the reversible PDC bit, wherein rotating the reversible PDC bit in a clockwise direction engages the at least one front cutter to cut into a subterranean formation, and wherein rotating the reversible PDC bit in a counter-clockwise direction engages the at least one rear cutter to cut into the subterranean formation.

A reversible polycrystalline diamond compact (PDC) bit. The reversible PDC bit includes at least one blade, at least one front cutter disposed on a first side of the at least one blade, and at least one rear cutter disposed on a second side of the at least one blade, wherein the first side is opposite to the second side along a circumferential direction of the reversible PDC bit, wherein rotating the reversible PDC bit in a clockwise direction engages the at least one front cutter to cut into a subterranean formation, and wherein rotating the reversible PDC bit in a counter-clockwise direction engages the at least one rear cutter to cut into the subterranean formation.

The invention relates to a rotary device (101) for a down-the-hole hammer (1), which rotary device is accommodated in a rotation motor housing (3) and mounted behind a drill housing (2) for transferring a torque to a drill bit (8) and a pressurized drive fluid (22) to a striking mechanism (4) for the drill bit. The rotary device includes a cam curve with a plurality of drive lobes (28:1-28:3) and working chambers (30:1, 30:2, 30:3) along a circumference in the rotation motor housing (3), a rotor disc (38) carrying a plurality of radially movable vanes (40:1-40:12), which are accommodated in piston tracks (41:1-41:12) in the rotor disc. Characteristics of the rotary device are that it includes; an odd integer of a number of drive lobes (28:1-28:3), which is equal to or higher than three; an odd integer of a number of working chambers (30:1, 30:2, 30:3), which is equal to or higher than three; an odd integer of a number of vanes (40:1-40:12), which is equal to or higher than three, and wherein said number of vanes are simultaneously pressurized in each working chamber (30:1, 30:2, 30:3).

The invention relates to a rotary device (101) for a down-the-hole hammer (1), which rotary device is accommodated in a rotation motor housing (3) and mounted behind a drill housing (2) for transferring a torque to a drill bit (8) and a pressurized drive fluid (22) to a striking mechanism (4) for the drill bit. The rotary device includes a cam curve with a plurality of drive lobes (28:1-28:3) and working chambers (30:1, 30:2, 30:3) along a circumference in the rotation motor housing (3), a rotor disc (38) carrying a plurality of radially movable vanes (40:1-40:12), which are accommodated in piston tracks (41:1-41:12) in the rotor disc. Characteristics of the rotary device are that it includes; an odd integer of a number of drive lobes (28:1-28:3), which is equal to or higher than three; an odd integer of a number of working chambers (30:1, 30:2, 30:3), which is equal to or higher than three; an odd integer of a number of vanes (40:1-40:12), which is equal to or higher than three, and wherein said number of vanes are simultaneously pressurized in each working chamber (30:1, 30:2, 30:3).