Mitigating stick-slip effects in rotary steerable tools

Patent metadata

Field	Value
Publication number	US-2016356089-A1
Application number	US-201414889908-A
Country	US
Kind code	A1
Filing date	Dec 29, 2014
Priority date	Dec 29, 2014
Publication date	Dec 8, 2016
Grant date	—

Abstract

Steering assemblies including a housing having an actuator positioned therein and operable to rotate a drive shaft. A planetary gearbox is positioned in the housing and includes a ring gear operatively coupled to the housing, a sun gear coupled to the drive shaft, and a planet carrier. A mechanical coupling operatively couples the ring gear to the housing such that rotation of the housing rotates the ring gear. The mechanical coupling is selected based on an ability of one or more mechanical parameters of the mechanical coupling to mitigate the stick-slip disturbance transmitted between the housing and the ring gear. An offset mandrel coupled to one of the sun gear and the planet carrier such that rotation of the one of the sun gear and the planet carrier causes the offset mandrel to correspondingly rotate, wherein the offset mandrel is independently rotatable with respect to the housing.

First claim

1 . A steering assembly, comprising:
a housing having an actuator positioned therein and operable to rotate a drive shaft; a planetary gearbox positioned within the housing and including a ring gear operatively coupled to the housing, one of a sun gear and a planet carrier coupled to the drive shaft, and one or more planet gears that rotate about the sun gear; a mechanical coupling operatively coupling the ring gear to the housing such that rotation of the housing rotates the ring gear, wherein the mechanical coupling is selected based on an ability of one or more mechanical parameters of the mechanical coupling to mitigate the stick-slip disturbance transmitted between the housing and the ring gear; and an offset mandrel coupled to one of the sun gear and the planet carrier such that rotation of the one of the sun gear and the planet carrier causes the offset mandrel to correspondingly rotate, wherein the offset mandrel is independently rotatable with respect to the housing.

2 . The steering assembly of claim 1 , wherein the ring gear is directly coupled to the housing via the mechanical coupling.

3 . The steering assembly of claim 1 , wherein the planetary gearbox further includes a gearbox carrier that interposes the housing and the ring gear, and wherein the ring gear is indirectly coupled to the housing via the mechanical coupling and the gearbox carrier.

4 . The steering assembly of claim 1 , wherein the mechanical coupling comprises a coupling engagement selected from the group comprising, a threaded coupling, a magnetic coupling, a welded coupling, a brazed coupling, a mechanically fastened coupling, an adhesive coupling, bellows, a spider coupling, and any combination thereof.

5 . The steering assembly of claim 1 , wherein the one or more mechanical parameters are parameters selected from the group consisting of torsional spring constant (k), damping coefficient (c), and inertia (J).

6 . The steering assembly of claim 1 , wherein the one or more mechanical parameters are optimized for downhole use to mitigate the stick-slip disturbance.

7 . The steering assembly of claim 1 , further comprising:
one or more sensors arranged proximate to the offset mandrel; and a controller communicably coupled to the one or more sensors, wherein the controller receives measurements taken by the one or more sensors and outputs a control signal that causes a change in rotational speed of the drive shaft.

8 . The steering assembly of claim 7 , wherein the controller is a PID controller.

9 . The steering assembly of claim 1 , wherein the actuator is selected from the group consisting of a fluid-controlled drive mechanism, a turbine, a mud motor, an electric motor, and any combination thereof.

10 . A method, comprising:
introducing a steering assembly into a wellbore on a drill string, the steering assembly including a housing having an actuator and a planetary gearbox positioned within the housing, the planetary gearbox including a ring gear operatively coupled to the housing, and one of a sun gear and a planet carrier coupled to a drive shaft of the actuator; rotating the drill string in a first direction and thereby rotating the housing and the ring gear in the first direction; operating the actuator to rotate the drive shaft and an offset mandrel coupled to one of the sun gear and the planet carrier in a second direction opposite the first direction; and mitigating stick-slip disturbance transmitted between the housing and the ring gear and to the offset mandrel with a mechanical coupling that operatively couples the ring gear to the housing, wherein the mechanical coupling is selected based on an ability of one or more mechanical parameters of the mechanical coupling to mitigate the stick-slip disturbance.

11 . The method of claim 10 , wherein operating the actuator comprises maintaining the offset mandrel geostationary with respect to a surrounding formation.

12 . The method of claim 10 , further comprising manipulating the one or more mechanical parameters of the mechanical coupling to mitigate the stick-slip disturbance, the one or more mechanical parameters being parameters selected from the group consisting of torsional spring constant (k), damping coefficient (c), and inertia (J).

13 . The method of claim 12 , wherein manipulating the one or more mechanical parameters of the mechanical coupling comprises changing a type of mechanical coupling to a more flexible mechanical coupling.

14 . The method of claim 12 , wherein manipulating the one or more mechanical parameters of the mechanical coupling comprises changing a material of at least one of the housing and the ring gear.

15 . The method of claim 12 , wherein manipulating the one or more mechanical parameters of the mechanical coupling comprises adding a dampening material to the mechanical coupling.

16 . The method of claim 12 , wherein manipulating the one or more mechanical parameters of the mechanical coupling comprises optimizing the one or more mechanical parameters to mitigate the stick-slip disturbance.

17 . The method of claim 10 , further comprising:
setting a target measurement at a controller; taking at least one measurement with one or more sensors arranged proximate to the offset mandrel and communicably coupled to the controller; receiving the at least one measurement with the controller; calculating an error based on a comparison of the at least one measurement and the target measurement; and outputting a control signal from the controller to cause a change in rotational speed of the drive shaft, wherein the control signal is based on the error.

18 . A well system, comprising:
a drill string extendable into a wellbore and having a drill bit coupled to an end of the drill string; a steering assembly arranged in the drill string and including a housing rotatable with the drill string, the housing having an actuator and a planetary gearbox positioned within the housing, and the planetary gearbox including a ring gear operatively coupled to the housing, and one of a sun gear and a planet carrier coupled to a drive shaft of the actuator; a mechanical coupling operatively coupling the ring gear to the housing such that rotation of the housing rotates the ring gear, wherein the mechanical coupling is selected based on one or more mechanical parameters of the mechanical coupling and the ability of the one or more mechanical parameters to mitigate stick-slip disturbance transmitted between the housing and the ring gear; and an offset mandrel coupled to one of the sun gear and the planet carrier such that rotation of the one of the sun gear and planet carrier causes the offset mandrel to correspondingly rotate, wherein the offset mandrel is independently rotatable with respect to the housing.

19 . The well system of claim 18 , wherein the mechanical coupling comprises a coupling engagement selected from the group comprising, a threaded coupling, a magnetic coupling, a welded coupling, a brazed coupling, a mechanically fastened coupling, an adhesive coupling, bellows, a spider coupling, and any combination thereof.

20 . The well system of claim 18 , wherein the one or more mechanical parameters are parameters selected from the group consisting of torsional spring constant (k), damping coefficient (c), and inertia (J).

21 . The well system of claim 18 , further comprising:
one or more sensors arranged proximate to the offset mandrel; and a controller communicably coupled to the one or more sensors, wh

Assignees

• Halliburton Energy Services Inc

Inventors

• Nanayakkara Ravi P
• Deolalikar Neelesh
• Winslow Daniel Martin

Classifications

• E21B47/024 Primary

  of devices in the borehole (determining slope or direction of the borehole E21B47/022) · CPC title

• E21B4/04

  Electric drives (E21B4/12 takes precedence) · CPC title

• E21B4/02

  Fluid rotary type drives · CPC title

• E21B44/005

  Below-ground automatic control systems · CPC title

• E21B7/062 Primary

  the tool shaft rotating inside a non-rotating guide travelling with the shaft (E21B7/067 and E21B7/068 take precedence) · CPC title