A downhole cleaning apparatus (10) comprising a tubular body (12). The tubular body (12) comprises comprising a plurality of openings (20) therethrough. Each opening (20) defines at least part of a helix extending longitudinally and circumferentially about the tubular body (12). The downhole cleaning apparatus (10) also includes a plurality of cleaning elements (22). Each cleaning element (22) is configured to extend through an opening (20) and to extend outwards from an outer surface of the tubular body (12). The cleaning elements (22) are distributed about the tubular body (12) and each cleaning element (22) defines at least part of a helix extending longitudinally and circumferentially about the tubular body. The openings (20) and the cleaning elements (22) are grouped to define a plurality of substantially continuous helical paths (18). Each helical path (18) extends substantially end to end of the tubular body and the helical paths (18) are distributed relative to each other to define a cleaning surface of at least 360 degrees.

A pulser for generating pressure pulses propagating through a column of drilling fluid in the drill string to the surface during drilling. The pulser may include a screen in the surface of a tubular housing to permit mud from the mud stream to enter into the pulser; an adjustable servo valve configured to receive the mud and including a removable servo poppet and a removable servo orifice member positioned in the tubular housing, wherein the adjustable servo valve is configured to allow the removable servo poppet and the removable servo orifice member to be replaced by another removable servo poppet and another removable servo orifice member to alter an inner diameter of an orifice of the adjustable servo valve to accommodate drilling conditions to increase a performance of the pulser generating pressure pulses for the mud stream returning to the surface.

A pulser for generating pressure pulses propagating through a column of drilling fluid in the drill string to the surface during drilling. The pulser may include a screen in the surface of a tubular housing to permit mud from the mud stream to enter into the pulser; an adjustable servo valve configured to receive the mud and including a removable servo poppet and a removable servo orifice member positioned in the tubular housing, wherein the adjustable servo valve is configured to allow the removable servo poppet and the removable servo orifice member to be replaced by another removable servo poppet and another removable servo orifice member to alter an inner diameter of an orifice of the adjustable servo valve to accommodate drilling conditions to increase a performance of the pulser generating pressure pulses for the mud stream returning to the surface.

A coiled tubing wellbore fluid may include a base fluid; and a crosslinked and branched polymeric fluid loss control agent formed from at least an acrylamide monomer and a sulfonated anionic monomer; wherein the coiled tubing wellbore fluid has a low shear rate viscosity, measured at 120° F. at 3 rpm, of at least 20,000 centipoise.

A coiled tubing wellbore fluid may include a base fluid; and a crosslinked and branched polymeric fluid loss control agent formed from at least an acrylamide monomer and a sulfonated anionic monomer; wherein the coiled tubing wellbore fluid has a low shear rate viscosity, measured at 120° F. at 3 rpm, of at least 20,000 centipoise.

A reactive torque automatic balancing device for a screw drilling tool includes an upper joint (1); a core cylinder (9) having an inner chamber in communication with the screw drilling tool (305) located downstream, so that drilling fluid from the inner chamber of the upper joint (1) flows to the screw drilling tool (305) through the inner chamber of the core cylinder (9) to allow the screw drilling tool to perform drilling; a lower joint (16) fixedly arranged at a lower end of the core cylinder (9); and an automatic balancing assembly, which is arranged between an outer wall of the core cylinder (9) and an inner wall of the upper joint (1), and driven by hydraulic pressure generated by a part of the drilling fluid flowing through the inner chamber of the upper joint (1).

A reactive torque automatic balancing device for a screw drilling tool includes an upper joint (1); a core cylinder (9) having an inner chamber in communication with the screw drilling tool (305) located downstream, so that drilling fluid from the inner chamber of the upper joint (1) flows to the screw drilling tool (305) through the inner chamber of the core cylinder (9) to allow the screw drilling tool to perform drilling; a lower joint (16) fixedly arranged at a lower end of the core cylinder (9); and an automatic balancing assembly, which is arranged between an outer wall of the core cylinder (9) and an inner wall of the upper joint (1), and driven by hydraulic pressure generated by a part of the drilling fluid flowing through the inner chamber of the upper joint (1).

A drill rod can include a body having an outer surface, an inner surface, a longitudinal axis aligned with a drilling axis, and at least one longitudinally extending groove extending radially outwardly from the longitudinal axis relative to the inner surface. The inner surface and the at least one longitudinally extending groove can cooperate to define an interior space through which an inner assembly can be received as the inner assembly is advanced and retracted relative to the drilling axis. The at least one longitudinally extending groove of the body of the drill rod can be configured to permit axial flow of fluid through the drill rod as portions of the inner assembly engage the inner surface of the body of the drill rod.

A drill rod can include a body having an outer surface, an inner surface, a longitudinal axis aligned with a drilling axis, and at least one longitudinally extending groove extending radially outwardly from the longitudinal axis relative to the inner surface. The inner surface and the at least one longitudinally extending groove can cooperate to define an interior space through which an inner assembly can be received as the inner assembly is advanced and retracted relative to the drilling axis. The at least one longitudinally extending groove of the body of the drill rod can be configured to permit axial flow of fluid through the drill rod as portions of the inner assembly engage the inner surface of the body of the drill rod.

A tubular member includes a central axis, a first end, a second end opposite the first end, and a throughbore extending axially from the first end to the second end. In addition, the tubular member includes a first connector at the first end and a second connector at the second end. Further, the tubular member includes a tubular region axially positioned between and axially spaced from the first connector and the second connector. The tubular member also includes a first upset axially positioned between the tubular region and the first connector. The first upset has an internal transition within the throughbore that increases an inner diameter of the throughbore when moving axially from the first upset to the tubular region. Moreover, the tubular member includes a first wear pad integrally formed on the tubular region. An outer diameter of the tubular member is greater along the first wear pad than along the tubular region.