Actively controlled rotary steerable system and method for drilling wells
First Claim
1. 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, pivotally rotating a bit shaft supported within said tool collar for rotational movement about a pivot point within said tool collar and in a direction counter to rotation of said tool collar, said bit shaft being rotatably driven by said tool collar and being adapted for supporting a drill bit;
transmitting steering control signals to said bit shaft positioning means causing synchronous pivotal counter-rotation of said bit shaft by said bit shaft positioning means 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
selectively rotationally braking said bit shaft positioning means in reference to external disturbances acting to divert said drill bit from its projected course.
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Abstract
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.
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Citations
69 Claims
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1. A method for drilling a well and simultaneously steering a drill bit with an actively controlled rotary steerable drilling system, comprising:
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rotating a tool collar connected to a drill string, said tool collar defining a longitudinal axis; with bit shaft positioning means, pivotally rotating a bit shaft supported within said tool collar for rotational movement about a pivot point within said tool collar and in a direction counter to rotation of said tool collar, said bit shaft being rotatably driven by said tool collar and being adapted for supporting a drill bit; transmitting steering control signals to said bit shaft positioning means causing synchronous pivotal counter-rotation of said bit shaft by said bit shaft positioning means 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 selectively rotationally braking said bit shaft positioning means in reference to external disturbances acting to divert said drill bit from its projected course. - View Dependent Claims (2, 3)
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4. A method for drilling a well and simultaneously steering a drill bit with an actively controlled rotary steerable drilling system, comprising:
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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. - View Dependent Claims (5, 6, 7, 8)
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9. 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:
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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. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. 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:
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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.
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33. 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:
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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.
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34. A method for drilling a wellbore with an actively controlled rotary steerable drilling system, comprising:
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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. - View Dependent Claims (35, 36)
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37. An actively controlled rotary steerable drilling system for well drilling, comprising:
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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. - View Dependent Claims (38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69)
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Specification