1
Michael K Russell, John D Barr: Steerable rotary drilling systems. Camco Drilling Group, November 30, 1993: US05265682 (187 worldwide citation)

A system for maintaining a downhole instrumentation package in a roll stabilised orientation with respect to a drill string comprises an instrument carrier which is mounted within a drill collar for rotation about the longitudinal axis of the collar. An impeller is mounted on the instrument carrier ...


2
John D Barr: Steerable rotary drilling systems. Camco Drilling Group of Hycalog, January 13, 1998: US05706905 (181 worldwide citation)

A modulated bias unit, for use in a steerable rotary drilling system, comprises a number of hydraulic actuators spaced apart around the periphery of the unit, each having a movable thrust member which is hydraulically displaceable outwardly for engagement with the formation of the borehole, and a co ...


3
John D Barr, Mark W Burrell, Robert A Russell, Richard Thorp, David Boast, John Clegg: Modulated bias units for steerable rotary drilling systems. Camco International, September 10, 1996: US05553678 (174 worldwide citation)

A modulated bias unit is provided for controlling the direction of drilling of a rotary drill bit when drilling boreholes in subsurface formations. The unit comprises a plurality of hydraulic actuators spaced apart around the periphery of the unit and having movable thrust members hydraulically disp ...


4
John D Barr, Richard E Thorp, Robert A Russell: Modulated bias unit for rotary drilling. Camco Drilling Group, May 28, 1996: US05520255 (157 worldwide citation)

A modulated bias unit, for controlling the direction of drilling of a rotary drill bit when drilling boreholes in subsurface formations, comprises a number of hydraulic actuators spaced apart around the periphery of the unit, each having a movable thrust member which is hydraulically displaceable ou ...


5
John D Barr: Modulated bias unit for rotary drilling. Camco Drilling Group, December 10, 1996: US05582259 (123 worldwide citation)

A modulated bias unit, for controlling the direction of drilling of a rotary drill bit when drilling boreholes in subsurface formations, comprises a number of hydraulic actuators spaced apart around the periphery of the unit. Each actuator comprises a movable thrust member which is hydraulically dis ...


6
John D Barr, John M Clegg, William C Motion: Steerable rotary drilling systems and method of operating such systems. Camco Drilling Group of Hycalog, September 8, 1998: US05803185 (120 worldwide citation)

A steerable rotary drilling system has a bottom hole assembly which includes, in addition to the drill bit, a modulated bias unit and a control unit, the bias unit comprising a number of hydraulic actuators around the periphery of the unit, each having a movable thrust member which is hydraulically ...


7
John D Barr, John M Clegg, William C Motion: Steerable rotary drilling systems. Camco International, Brigitte Jeffery, July 18, 2000: US06089332 (119 worldwide citation)

A steerable rotary drilling system has a bottom hole assembly which includes, in addition to the drill bit, a modulated bias unit and a control unit, the bias unit comprising a number of hydraulic actuators around the periphery of the unit, each having a movable thrust member which is hydraulically ...


8
John D Barr, John M Clegg, William C Motion: Method of operating a steerable rotary drilling system. Camco Drilling Group of Hycalog, November 11, 1997: US05685379 (108 worldwide citation)

A steerable rotary drilling system comprises a bottom hole assembly which includes, in addition to a drill bit, a modulated bias unit and a control unit including an instrument carrier which is rotatable relative to the bias unit. The bias unit comprises a number of hydraulic actuators spaced apart ...


9
John D Barr, William C Motion, Michael K Russell: System and method of controlling rotation of a downhole instrument package. Camco Drilling Group of Hycalog, December 9, 1997: US05695015 (94 worldwide citation)

A system for controlling the rotation of a roll stabilizable control unit in a steerable rotary drilling assembly comprises an instrument carrier rotatably mounted on a support connected to the drill string. A first rotatable impeller is mounted for rotation by a flow of drilling fluid over the impe ...


10
John D Barr: Rotary drill bits with nozzle former and method of manufacturing. NL Petroleum Products, Browning Bushman Zamecki & Anderson, September 22, 1987: US04694919 (75 worldwide citation)

A method of manufacturing by a power metallurgy process a rotary drill bit including a bit body having an external surface on which are mounted a plurality of preform cutting elements, and an inner passage for supplying drilling fluid to at least one nozzle located in a socket at the external surfac ...



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