An actively controlled rotary steerable drilling system for directional drilling of wells having a tool collar rotated by a drill string during well drilling. A bit shaft has an upper portion within the tool collar and a lower end extending from the collar and supporting a drill bit. The bit shaft is omni-directionally pivotally supported intermediate its upper and lower ends by a universal joint within the collar and is rotatably driven by the collar. To achieve controlled steering of the rotating drill bit, orientation of the bit shaft relative to the tool collar is sensed and the bit shaft is maintained geostationary and selectively axially inclined relative to the tool collar during drill string rotation by rotating it about the universal joint by an offsetting mandrel that is rotated counter to collar rotation and at the same frequency of rotation. An electric motor provides rotation to the offsetting mandrel with respect to the tool collar and is servo-controlled by signal input from position sensing elements such as magnetometers, gyroscopic sensors, and accelerometers which provide real time position signals to the motor control. In addition, when necessary, a brake is used to maintain the offsetting mandrel and the bit shaft axis geostationary. Alternatively, a turbine is connected to the offsetting mandrel to provide rotation to the offsetting mandrel with respect to the tool collar and a brake is used to servo-control the turbine by signal input from position sensors.

Actively controlled rotary steerable system and method for drilling wells

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 132 spaced apart around the periphery of the unit and having movable thrust members 134 hydraulically displaceable outwardly for engagement with the formation of the borehole being drilled. Each actuator 134 has an inlet passage 150 for connection to a source 124 of drilling fluid under pressure and an outlet passage 174 for communication with the annulus. A selector control valve 160,166 connects the inlet passages 150 in succession to the source of fluid under pressure, as the unit rotates, and a choke 172 is provided to create a pressure drop between the source of fluid under pressure and the selector valve. A further choke 176,180 is provided in the outlet passage from each actuator unit. The actuators and control valve arrangements may take a number of different forms.

Modulated bias units for steerable rotary drilling systems

An actively controlled rotary steerable drilling system for directional drilling of wells, the system having a rotary drive component rotatable within a tubular sliding tool collar that incorporates elastic anti-rotation members to maintain a coupled relation with the borehole wall during drilling. An offsetting mandrel is supported within the tool collar by a knuckle joint for pivotal movement and for rotation relative to the tool collar and has a lower end extending from the tool collar and supporting a drill bit. To achieve controlled steering of the rotating drill bit, orientation of the tool collar is sensed and the offsetting mandrel is maintained geostationary and selectively axially inclined relative to the tool collar by orienting it about the knuckle joint. An alternator and a hydraulic pump, located within the tool collar, are driven by relative rotation of the rotary drive component with the tool collar to produce electric power and hydraulic pressure for the electronics package of the tool and for actuation of hydraulic system components. Hydraulic cylinder and piston assemblies, actuated by tool position signal responsive solenoid valves, control the angular position of the offsetting mandrel with respect to the tool collar. The hydraulic pistons are servo-controlled responsive to signal input from tool position sensing systems such as magnetometers and accelerometers which provide real-time position signals to the hydraulic control system.

Rotary steerable well drilling system utilizing sliding sleeve

An actively controlled rotary steerable drilling system for directional drilling of wells including a tubular rotary tool collar having rotatably mounted thereabout a substantially non-rotatable sliding sleeve incorporating a plurality of elastic coupling members to maintain the sliding sleeve in coupled relation with the borehole wall during drilling. An offsetting mandrel is supported within the tool collar by a knuckle joint for pivotal movement and is rotatably driven by the tool collar and has a lower end extending from the collar and adapted for support of a drill bit. To achieve controlled steering of the rotating drill bit, orientation of the drilling tool is sensed by navigation sensors and the offsetting mandrel is maintained geostationary and selectively axially inclined relative to the tool collar by orienting it about the knuckle joint responsive to navigation sensors. An alternator and a hydraulic pump, located within the tool collar, are driven by a power source driven by the flowing drilling fluid to produce electric power and hydraulic pressure for supplying electrical power for the electronics package of the tool and for actuation of hydraulic system components. Hydraulic cylinder and piston assemblies, actuated by tool position signal responsive servo-valves, control the angular position of the offsetting mandrel with respect to the tool collar. The hydraulic pistons are servo-controlled responsive to signal input from the navigation sensors and from other tool position sensing systems which provide real-time position signals to the hydraulic position control system.

Rotary steerable well drilling system utilizing hydraulic servo-loop

A steerable drilling system comprising a bottom hole assembly (18) including an upper section (22) and a steering section (24), a swivel (26) permitting adjustment of the orientation of an axis of the steering section (24) relative to that of the upper section (22), a downhole motor operative to drive the steering section (24) for rotation relative to the upper section (22), and a plurality of actuators (34) operable to control the orientation of the axis of the steering section (24) relative to that of the upper section (22), the (actuators 34) being mounted upon one of the steering section (24) and the upper section (22,) a high speed sliding contact being formed between the actuators (34) and the other of the steering section (24) and the upper section (22).

Steerable Drilling System

The invention disclosed herein provides a mechanism and method for positive drill bit guidance during well drilling operations. The guidance device includes a control arm or paddle which, due to hydraulic pressure, pivots to steer the drill bit towards its target area. As the paddle applies pressure to the wall of the well, the drill bit is then turned from the contacted area of the well wall in the desired direction.

Royce E. Baker

Papers

Bit guidance device and method