A downhole tool that includes a tractor for assisting movement of the tool through deviated portions of a wellbore. The tractor includes a working fluid that damps vibrations in the tractor by adjusting the viscosity in the fluid. In an example, the working fluid is a magnetorheological fluid that h
A downhole tool that includes a tractor for assisting movement of the tool through deviated portions of a wellbore. The tractor includes a working fluid that damps vibrations in the tractor by adjusting the viscosity in the fluid. In an example, the working fluid is a magnetorheological fluid that has a viscosity that changes in response to applied electrical energy. The working fluid, which may be used for powering actuators on the tractor, may contain a suspension of magnetic particles.
대표청구항▼
1. A tractor assembly for use with a downhole tool, the tractor assembly comprising: an actuator comprising a cylinder, a piston in the cylinder that is selectively moveable in the cylinder between a deployed position and a stowed position, and a piston rod coupled to a side of the piston;a gripper
1. A tractor assembly for use with a downhole tool, the tractor assembly comprising: an actuator comprising a cylinder, a piston in the cylinder that is selectively moveable in the cylinder between a deployed position and a stowed position, and a piston rod coupled to a side of the piston;a gripper coupled to an end of the piston rod distal from the piston, and selectively moveable between a retracted position substantially contained within a body of the downhole tool and an extended position in contact with a wellbore wall;fluid in the cylinder that is retained in the cylinder on a side of the piston distal from the piston rod and isolated from the piston rod;magnetically responsive particles in the fluid; anda magnetic field source for selectively generating a magnetic field that intersects the fluid, so that a viscosity of the fluid increases when the magnetic field is applied to the fluid and dampens vibration in the tractor assembly, so that an urging force is selective transferred from the fluid to the piston. 2. The tractor assembly of claim 1, wherein the magnetic field source comprises a winding proximate a portion of the fluid and in communication with a source of electricity for generating the magnetic field that is applied to the fluid. 3. The tractor assembly of claim 2, further comprising a controller in communication with the source of electricity for regulating the amount of vibration damping by the fluid by adjusting a magnitude of the magnetic field. 4. The tractor assembly of claim 3, further comprising a sensor for detecting tractor assembly operating conditions in a wellbore and communicating the operating conditions to the controller. 5. The tractor assembly of claim 4, wherein the tractor assembly operating conditions include a frictional force between the gripper and wellbore wall and wherein the controller adjusts the magnitude of the magnetic field in response to the sensed frictional force. 6. The tractor assembly of claim 2, wherein the windings comprise two windings that are disposed distal from one another and within the cylinder, so that when the windings are energized flux lines are generated in the fluid that project transverse to a length of the cylinder. 7. The tractor assembly of claim 1, wherein the gripper is selected from the group consisting of a roller, a track assembly, and linkage arms. 8. The tractor assembly of claim 1, wherein the fluid comprises carrier oil and the particles range in size from about 0.1 microns to about 10 microns. 9. A downhole tool disposable in a wellbore, the downhole tool comprising: a body;a hydraulic actuation system in the body comprising a cylinder, a piston in the cylinder, a piston rod attached to a side of the piston, and a magnetorheological fluid in the cylinder that is retained in the cylinder and isolated to a side of the piston opposite the piston rod, and that is selectively pressurized by a pressure source;a gripper assembly mounted to the body, coupled to the piston rod, and selectively moveable between a stowed position substantially in the body and a deployed position in contact with a wall of the wellbore in response to movement of the piston and piston rod that occurs under selective pressurization of the fluid by the pressure source; anda selectively activatable magnetic field source, so that when the magnetic field is activated a magnetic field forms in the magnetorheological fluid, thereby altering a viscosity of the magnetorheological fluid and damping vibration in the hydraulic actuation system and the gripper assembly. 10. The downhole tool of claim 9, wherein the gripper assembly comprises a component selected from the group consisting of a roller, a track assembly, and linkage arms. 11. The downhole tool of claim 9, wherein the magnetorheological fluid comprises magnetic particles that range in size from about 0.1 microns to about 10 microns. 12. A method of pulling a downhole assembly through a wellbore, the method comprising: (a) providing with the downhole assembly an actuator having a piston selectively moveable in a cylinder between a deployed position and a stowed position, a gripper coupled to a piston rod attached to a side of the piston and that is deployed with axial movement of the piston, and magnetorheological fluid retained in the cylinder that is isolated to a side of the piston opposite from the piston rod and does not flow from the cylinder;(b) deploying the downhole assembly in the wellbore;(c) pressurizing the magnetorheological fluid to move the piston and piston rod and to deploy the gripper into an extended position in contact with the wellbore wall;(d) moving at least a portion of the gripper with respect to the wellbore wall so that the downhole assembly is motivated within the wellbore;(e) sensing operating conditions of the downhole assembly; and(f) selectively energizing the magnetorheological fluid in response to the step of sensing to adjust viscosity of the magnetorheological fluid. 13. The method of claim 12, wherein the operating conditions of step (e) comprise parameters selected from the group consisting compressive strength of the wellbore wall, a profile of the wellbore wall, and a frictional force between the gripper and the wellbore wall. 14. The method of claim 12, wherein the step of adjusting viscosity of the magnetorheological fluid damps vibration in the downhole assembly. 15. The method of claim 12, wherein the step of sensing operating conditions of the downhole assembly comprises monitoring a frictional force between the gripper and the wellbore wall and wherein the step of selectively energizing the magnetorheological fluid adjusts the viscosity of the magnetorheological fluid so the frictional force between the gripper and the wellbore wall is at a value to prevent slippage between the gripper and the wellbore wall. 16. The method of claim 12, wherein the frictional force between the gripper and the wellbore wall is at a minimum value to prevent slippage between the gripper and the wellbore wall. 17. The method of claim 12, wherein a controller is used to determine an amount of electricity for energizing the magnetorheological fluid. 18. The method of claim 12, wherein energizing the magnetorheological fluid comprises flowing electricity through a winding proximate a portion of the magnetorheological fluid. 19. The method of claim 12, further comprising creating flux lines in the fluid that extend generally parallel with an axis of the downhole assembly. 20. The method of claim 12, further comprising creating flux lines in the fluid that extend generally transverse to an axis of the downhole assembly.
연구과제 타임라인
LOADING...
LOADING...
LOADING...
LOADING...
LOADING...
이 특허에 인용된 특허 (7)
Sheiretov, Todor K.; Post, Roger A.; Roy, Carl J.; Cordera, Joseph F., Constant force actuator.
※ AI-Helper는 부적절한 답변을 할 수 있습니다.