1
Michael K Russell, John D Barr: Steerable rotary drilling systems. Camco Drilling Group, November 30, 1993: US05265682 (207 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 (190 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, Richard E Thorp, Robert A Russell: Modulated bias unit for rotary drilling. Camco Drilling Group, May 28, 1996: US05520255 (165 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 ...


4
Richard E Thorp: Modulated bias unit for rotary drilling. Camco Drilling Group, September 10, 1996: US05553679 (144 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 ...


5
John D Barr: Modulated bias unit for rotary drilling. Camco Drilling Group, December 10, 1996: US05582259 (130 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 M Clegg: Rotary drill bits. Camco Drilling Group, February 16, 1993: US05186268 (129 worldwide citation)

A rotary drill bit comprises a bit body carrying a plurality of primary preform cutting elements defining a primary cutting profile. The bit includes means to apply a lateral imbalance force to the bit as it rotates, and a portion of the outer periphery of the bit body includes a low friction bearin ...


7
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 (129 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 (117 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
Malcolm R Taylor, Andrew Keohane: Rotary drill bits and methods of designing such drill bits. Camco Drilling Group, June 29, 1993: US05222566 (110 worldwide citation)

A rotary drill bit comprises a bit body having a shank for connection to a drill string, a plurality of cutter assemblies mounted on the bit body, and a passage in the bit body for supplying drilling fluid to the surface of the bit. Certain cutter assemblies on the bit body are adapted to exhibit a ...


10
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 (103 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 ...