Abstract: A technique facilitates delivery of high pressure actuating fluid, e.g. drilling mud, to a plurality of actuators. The technique employs a valve system in which high pressure actuating fluid is delivered from inside a rotor to outer stator ports on a surrounding stator. The construction and arrangement of the rotor and stator reduces the inherent instability and susceptibility to sticking that can otherwise affect the operation of the valve.

Abstract: A technique facilitates tool operation with mobile pistons submitted to differential pressure. The technique utilizes a mobile piston slidably mounted in a corresponding piston passage. The piston passage is defined by a passage wall surface, and the piston may be moved linearly along the piston passage under the influence of an actuating fluid or to pump a fluid. The exterior surface of the piston and/or the passage wall surface have a groove or a plurality of grooves located and arranged to collect particulates from the fluid. Removal of the particulates facilitates actuator piston function by reducing, for example, third body abrasion and jamming of the piston.

Abstract: A technique facilitates directional drilling of boreholes. A steerable system has a plurality of actuator pistons slidably mounted in a mechanical structure. The mechanical structure comprises a radially inward portion containing ports to deliver a portion of drilling mud to the plurality of actuator pistons. The mechanical structure also has a radially outward portion positioned to define a main flow passage extending longitudinally through the steerable system between the radially inward portion and the radially outward portion of the mechanical structure.

Abstract: A technique facilitates pressure compensation with respect to a tool while also limiting detrimental influx of contaminants. A pressure compensation mechanism comprises a fluid trap chamber which is in fluid communication with a clean fluid chamber via a connector passage. The fluid trap chamber also is in communication with an external pressure region via an inlet passage. The connector passage is located such that a potentially contaminating fluid, e.g. water, entering via the inlet passage is isolated from the clean fluid chamber. The connector passage remains isolated regardless of whether the pressure compensation mechanism is in a vertical operational position or a deviated operational position.

Abstract: A system in which a drill string is disposed within a wellbore that extends from a wellsite surface to a subterranean formation. At least three rotary steerable system (RSS) modules are collectively coupled in series between the drill string and a drill bit. Each RSS module includes at least three steering pads spaced circumferentially apart around a perimeter of the RSS module, and a valve operable to sequentially actuate the steering pads. The system also includes a controller operable to independently actuate the valve of each RSS module simultaneously.

Abstract: A technique facilitates tool operation with mobile pistons submitted to differential pressure. The technique utilizes a mobile piston slidably mounted in a corresponding piston passage. The piston passage is defined by a passage wall surface, and the piston may be moved linearly along the piston passage under the influence of an actuating fluid or to pump a fluid. The exterior surface of the piston and/or the passage wall surface have a groove or a plurality of grooves located and arranged to collect particulates from the fluid. Removal of the particulates facilitates actuator piston function by reducing, for example, third body abrasion and jamming of the piston.

Abstract: A technique facilitates delivery of high pressure actuating fluid, e.g. drilling mud, to a plurality of actuators. The technique employs a valve system in which high pressure actuating fluid is delivered from inside a rotor to outer stator ports on a surrounding stator. The construction and arrangement of the rotor and stator reduces the inherent instability and susceptibility to sticking that can otherwise affect the operation of the valve.

Abstract: A technique facilitates directional drilling of boreholes. A steerable system has a plurality of actuator pistons slidably mounted in a mechanical structure. The mechanical structure comprises a radially inward portion containing ports to deliver a portion of drilling mud to the plurality of actuator pistons. The mechanical structure also has a radially outward portion positioned to define a main flow passage extending longitudinally through the steerable system between the radially inward portion and the radially outward portion of the mechanical structure.

Abstract: A technique facilitates communication of electrical signals in harsh environments and between components that undergo relative rotation with respect to each other. The technique comprises rotatably mounting a first component with respect to a second component. The first component also is electrically coupled with the second component via an electrical coupler. The electrical coupler may comprise a first electrical contact located at the first component and a second electrical contact located at the second component. The first electrical contact is conductively connected with the second electrical contact via a conductive bearing. The conductive bearing is located in a volume which is filled with a substantially incompressible fluid to protect the bearing.

Abstract: A turbine for use in a downhole drill string including an elongated casing defining an interior and a plurality of motor units in the interior. Each motor unit has a rotor and a stator. A torque transmission couplings connects each of the plurality of motor units to the drill string. The torque transmission couplings having flexible linkages. As a result, the power section has tight tolerances for the clearance at the tips of the rotors because the motor units are relatively stiff. The flexing normally obtained by bending the rotor shaft is accomplished and absorbed in the flexible linkages.

Abstract: The present invention relates to systems and methods for controlling downhole motors and drilling systems incorporating such systems and methods. One aspect of the invention provides a downhole drilling system including: a downhole motor, a transmission coupled to the downhole motor, and a drill bit coupled to the transmission. Another aspect of the invention provides a method of drilling a borehole in a subsurface formation including the steps of: providing a drill string including a downhole motor, a transmission coupled to the downhole motor, and a drill bit coupled to the transmission; and rotating the drill string while flowing a fluid through the drill string to the downhole motor, thereby powering the downhole motor, thereby rotating the transmission and the drill bit.