Actively controlled rotary steerable system and method for drilling wells

A method for drilling a well and simultaneously steering a drill bit with an actively controlled rotary steerable drilling system, comprising:

• rotating a tool collar connected to a drill string, said tool collar defining a longitudinal axis;
• with bit shaft positioning means, counter-rotating a bit shaft supported for rotational movement about a pivot point within said tool collar, said bit shaft being rotatably driven by said tool collar and being adapted for supporting a drill bit;
• dynamically sensing the angular position of said longitudinal axis of said bit shaft relative to said longitudinal axis of said tool collar, the position of said tool collar with respect to the earth and the orientation of said longitudinal axis of said bit shaft relative to said tool collar and providing position signals;
• and
• processing said position signals and developing steering control signals causing synchronous pivotal counter-rotation of said bit shaft about said pivot point by said bit shaft positioning means with respect to rotation of said tool collar for maintaining said longitudinal axis of said bit shaft substantially geostationary and selectively axially inclined relative to the longitudinal axis of said tool collar during rotation of said bit shaft by said tool collar;
• and
• selectively rotationally braking said bit shaft positioning means in reference to external disturbances acting to divert said drill bit from its projected course.

A method for drilling a wellbore with a rotary steerable drilling system connected to a drill string while simultaneously selectively orienting a drill bit being rotated thereby, comprising:

• rotating a tool collar with a rotating drill string, said tool collar defining a longitudinal axis and having a bit shaft pivotally mounted therein, said bit shaft defining a longitudinal axis disposed for omnidirectional pivotal movement relative to said tool collar;
• operating a turbine within said tool collar with drilling fluid flowing through said tool collar and rotating an output shaft of said turbine;
• driving an alternator with said output shaft of said turbine and producing an electrical output of said alternator;
• operating an electric motor with said electrical output of said alternator and with a rotary output shaft of said electric motor driving an offsetting mandrel within said tool collar in synchronous pivotal counter-rotational relation with tool collar rotation and translating rotary motion of said offsetting mandrel into pivotal movement of said bit shaft within said tool collar for geostationary orientation of said longitudinal axis of said bit shaft in selected angular relation with said longitudinal axis of said tool collar for drilling a curved wellbore;
• and
• selectively rotationally braking said offsetting mandrel in reference to external disturbances acting to divert said drill bit from its projected course.

A method for drilling a wellbore with a rotary steerable drilling system connected to a drill string while simultaneously selectively orienting a drill bit being rotated thereby, comprising:

• rotating a tool collar with a rotating drill string, said tool collar defining a longitudinal axis and having a bit shaft pivotally mounted therein, said bit shaft defining a longitudinal axis disposed for omnidirectional pivotal movement relative to said tool collar;
• operating a turbine within said tool collar with drilling fluid flowing through said tool collar and rotating an output shaft of said turbine;
• driving an alternator with said output shaft of said turbine and producing an electrical output of said alternator;
• operating an electric motor with said electrical output of said alternator and with a rotary output shaft of said electric motor driving an offsetting mandrel within said tool collar in synchronous pivotal counter-rotational relation with tool collar rotation, said offsetting mandrel defines an eccentric receptacle having at least one eccentric ring therein and said bit shaft is engaged within said eccentric ring and translating rotary motion of said offsetting mandrel into pivotal movement of said bit shaft within said tool collar for geostationary orientation of said longitudinal axis of said bit shaft in selected angular relation with said longitudinal axis of said tool collar for drilling a curved wellbore;
• and
• selectively adjusting the relative position of said eccentric ring with respect to said eccentric receptacle for selectively establishing said angular relation of said longitudinal axis of said bit shaft relative to said longitudinal axis of said tool collar at a selected angle between 0 and a predetermined angle.

A method for drilling a wellbore with a rotary steerable drilling system while simultaneously selectively orienting a drill bit being rotated by a rotatable tool collar of said rotary steerable drilling system, said tool collar defining a longitudinal axis and connected for rotation by a drill string of well drilling equipment, comprising:

• rotating said tool collar having a bit shaft mounted therein for pivotal movement relative to said tool collar, said bit shaft defining a longitudinal axis and being rotatably driven by said tool collar;
• counter-rotating an offsetting mandrel within said tool collar, said offsetting mandrel having an offset driving connection with said bit shaft and translating rotary motion of said offsetting mandrel into rotary pivoting of said bit shaft about a pivot point within said tool collar;
• applying braking for maintaining said longitudinal axis of said bit shaft geostationary and in predetermined angular relation with said longitudinal axis of said tool collar;
• and
• selectively orienting said longitudinal axis of said bit shaft in angular relation with said longitudinal axis of said tool collar for causing the drill bit to drill a curved wellbore in a selected direction.

A method for drilling a wellbore with an actively controlled rotary steerable drilling system, comprising:

• rotating a tool collar connected to a drill string, said tool collar defining a longitudinal axis;
• imparting driving rotation to a bit shaft pivotally supported by said tool collar for pivotal movement of the longitudinal axis thereof about a pivot point relative to the longitudinal axis of said tool collar;
• driving a turbine mounted within said tool collar by drilling fluid flow through said tool collar, said turbine having rotary driving connection with an offsetting mandrel mounted for rotation within said tool collar, said offsetting mandrel imparting pivotal counter-rotation to said bit shaft at the same rotary frequency as rotation of said tool collar and establishing a selected angular relation of said longitudinal axis of said bit shaft with said longitudinal axis of said tool collar;
• and
• selectively applying braking force for maintaining said longitudinal axis of said bit shaft substantially geostationary and selectively axially inclined with respect to said longitudinal axis of said tool collar for selectively steering said drill bit and the wellbore being drilled thereby.

An actively controlled rotary steerable drilling system for well drilling, comprising:

• a tool collar being adapted for connection to a drill string for rotation by the drill string and defining a longitudinal axis;
• a bit shaft being supported within said tool collar for pivotal movement about a pivot point and being rotatably driven by said tool collar, said bit shaft defining a longitudinal axis and being adapted for supporting a drill bit;
• a bit shaft position sensor within said tool collar for dynamically sensing the angular position of said longitudinal axis of said bit shaft relative to said longitudinal axis of said tool collar and providing bit shaft position signals;
• system electronics processing said bit shaft position signals of said bit shaft position sensor and causing synchronous pivotal counter-rotation of said bit shaft about said pivot point with respect to rotation of said tool collar and maintaining said longitudinal axis of said bit shaft substantially geostationary and selectively axially inclined relative to the longitudinal axis of said tool collar during rotation of said bit shaft by said tool collar;
• and
• a brake within said tool collar for applying a braking force for maintaining said longitudinal axis of said bit shaft substantially geostationary and selectively axially inclined with respect to said longitudinal axis of said tool collar for selectively steering said drill bit and the wellbore being drilled thereby.