Modular rotary steerable actuators, steering tools, and rotary steerable drilling systems with modular actuators

A steering tool for use in directing a drill string when drilling a borehole in an earth formation, the drill string including a drive shaft and a swash plate, the steering tool comprising:

• a tubular housing having an exterior surface and defining a housing bore configured to receive therethrough the drive shaft;
• a plurality of modular actuators circumferentially spaced about the exterior surface of the housing, each of the modular actuators including:
• a cartridge coupled to the exterior surface of the housing;
• a fluid reservoir sealed within the cartridge;
• a hydraulically actuated actuator piston slidably disposed at least partially inside the cartridge, the actuator piston being movable between deactivated and activated positions;
• and
• a hydraulic control system sealed within the cartridge and fluidly coupling the fluid reservoir to the actuator piston, the hydraulic control system being configured to regulate movement of the actuator piston between the deactivated position and the activated position such that the actuator piston selectively moves the drive shaft and thereby changes the direction of the drill string.

A rotary steerable drilling system comprising:

• a drill-pipe string;
• a tubular housing operatively coupled to a distal end of the drill-pipe string, the tubular housing having an exterior surface and defining a housing bore;
• a drive shaft extending through the tubular housing, the drive shaft including a plurality of ramped surfaces;
• a drill bit rotatably coupled to the tubular housing via the drive shaft;
• a steering controller;
• and
• a plurality of modular actuators circumferentially spaced about the exterior surface of the housing, each of the modular actuators including:
• a cartridge coupled to the exterior surface of the housing;
• an electrical connector electrically connecting the modular actuator with the steering controller;
• a fluid reservoir sealed within the cartridge;
• a hydraulically actuated actuator piston slidably disposed at least partially inside the cartridge, the actuator piston being movable between deactivated and activated positions;
• and
• a hydraulic control system sealed within the cartridge and fluidly coupling the fluid reservoir to the actuator piston, the hydraulic control system being configured to regulate movement of the actuator piston from the activated to the deactivated positions such that the actuator piston presses against one of the ramped surfaces of the drive shaft and thereby changes the direction of the drill string.