초록 ▼

A downhole tractor is provided that may be used in open or cased wells, and is also designed for use in open holes having a variety of soil/formation consistencies (e.g., soft, firm, rigid, etc.), varying diameters and non-uniform and irregular bore profiles. The tractor may include a track assembly

A downhole tractor is provided that may be used in open or cased wells, and is also designed for use in open holes having a variety of soil/formation consistencies (e.g., soft, firm, rigid, etc.), varying diameters and non-uniform and irregular bore profiles. The tractor may include a track assembly including a plurality of idler wheels and a continuous track rotatably disposed around the idler wheels. A motor may be adapted to rotate the track around the idler wheels. Upper and lower arms may be pivotally connected to opposite ends of the track assembly and pivotally connected to a tractor housing. An actuator arm or link assembly may be provided to impart an outward force to the track assembly to move the track assembly outwardly into an open position and a retracting force to retract the track assembly into a closed position. A rotatable screw may be connected to a second motor, or a rod may be connected to a hydraulic system, to actuate the actuator arm or link assembly.

대표청구항 ▼

The invention claimed is: 1. A downhole tractor comprising: a track assembly including a rotatable track; a motor adapted to rotate the track; a lower arm having a first end supported by a tractor housing, and a second end connected to the track assembly; an upper arm having a first end supported b

The invention claimed is: 1. A downhole tractor comprising: a track assembly including a rotatable track; a motor adapted to rotate the track; a lower arm having a first end supported by a tractor housing, and a second end connected to the track assembly; an upper arm having a first end supported by the tractor housing, and a second end connected to the track assembly; and an actuator arm mounted to move the track assembly between open and closed positions. 2. The downhole tractor of claim 1, wherein the track is rotatably disposed about a plurality of wheels mounted to the track assembly. 3. The downhole tractor of claim 1, wherein the track includes a plurality of wheels. 4. The downhole tractor of claim 1, further including one of a rotatable screw and a rod, and wherein the actuator arm includes a first end pivotally connected to one of the screw and the rod and a second end pivotally connected to the track assembly. 5. The downhole tractor of claim 1, wherein the track rotates along a path defined by the general shape of one of an oval, parallelogram, trapezoid and triangle. 6. The downhole tractor of claim 1, further including a transmission connected between the motor and a driven wheel adapted to rotate the track. 7. The downhole tractor of claim 1, further including a rotatable screw connected, directly or indirectly, to the actuator arm, whereby the screw causes the actuator arm to move the track assembly towards its open position when the screw is rotated in a first direction and to move the track assembly towards its closed position when the screw is rotated in second direction. 8. The downhole tractor of claim 1, further including a rod connected to the actuator arm, whereby the rod causes the actuator arm to move the track assembly towards its open position when the rod is moved in a first direction and to move the track assembly towards its closed position when the rod is moved in second direction. 9. The downhole tractor of claim 1, wherein the first end of the lower arm is disposed for movement within a slot in the tractor housing. 10. The downhole tractor of claim 1, further including a slider assembly connected to the track assembly and the lower arm, and adapted to permit relative movement between the track assembly and the lower arm. 11. The downhole tractor of claim 1, further including a slider assembly having an inner member disposed for movement within a bore of an outer member, one of the inner member and outer member being connected to the upper arm and the other of the inner member and the outer member being connected to the track assembly. 12. The downhole tractor of claim 1, wherein the actuator arm includes a wheel engaged with a ramp mounted to the tractor housing. 13. The downhole tractor of claim 1, wherein the track assembly further includes a driven wheel coupled directly or indirectly to the motor. 14. The downhole tractor of claim 1, wherein the motor is coupled directly or indirectly to a rotatable screw that is engaged with the track, whereby rotation of the screw causes rotation of the track. 15. A downhole tractor comprising: a track assembly including a plurality of idler wheels and a continuous track rotatably disposed around the idler wheels; a motor adapted to rotate the track around the idler wheels; a lower arm having a first end pivotally connected to a tractor housing, and a second end pivotally connected to the track assembly; an upper arm having a first end pivotally connected to the tractor housing, and a second end pivotally connected to the track assembly; one of a rotatable screw and a rod; and a link assembly including a first link having a first end pivotally connected to one of the screw and the rod and a second end pivotally connected to the track assembly, and a second link having a first end pivotally connected to the track assembly and a second end pivotally mounted to the tractor housing. 16. The downhole tractor of claim 15, wherein the second end of the first link and the first end of the second link are pivotally mounted to the track assembly at a pivot point on the track assembly. 17. The downhole tractor of claim 15, wherein the first end of the lower arm is disposed for movement within a slot in the tractor housing. 18. The downhole tractor of claim 15, wherein the track rotates along a path defined by the general shape of one of an oval, parallelogram, trapezoid and triangle. 19. The downhole tractor of claim 15, further including a transmission connected between the motor and a driven wheel. 20. The downhole tractor of claim 15, further including a hydraulic system adapted to move the rod between a first position in which the track assembly is in a closed position and a second position in which the track assembly is in an open position. 21. The downhole tractor of claim 15, further including a second motor adapted to rotate the screw in a first direction to cause the track assembly to move towards an open position and a second direction to cause the track assembly to move towards a closed position. 22. The downhole tractor of claim 15, wherein one of the screw and rod is adapted to move the first end of the first link in a direction generally parallel to a central axis of the tractor housing. 23. The downhole tractor of claim 15, further including a slider assembly connected to the track assembly and the lower arm, and adapted to permit relative movement between the track assembly and the lower arm. 24. The downhole tractor of claim 15, wherein the track assembly further includes a driven wheel coupled directly or indirectly to the motor. 25. The downhole tractor of claim 15, wherein the motor is coupled directly or indirectly to a second rotatable screw that is engaged with the track, whereby rotation of the second rotatable screw causes rotation of the track. 26. A downhole tractor comprising: a track assembly including a plurality of idler wheels and a continuous track rotatably disposed around the idler wheels; a motor adapted to rotate the track around the idler wheels; a lower arm having a first end pivotally connected to a tractor housing, and a second end pivotally connected to the track assembly; an upper arm having a first end pivotally connected to the tractor housing, and a second end pivotally connected to the track assembly; one of a rotatable screw and a rod; and an actuator arm having a first end pivotally connected to one of the screw and the rod, a second end pivotally connected to the track assembly, and a wheel engaged with a ramp connected to the tractor housing. 27. The downhole tractor of claim 26, wherein the first end of the lower arm is disposed for movement within a slot in the tractor housing. 28. The downhole tractor of claim 26, further including a transmission connected between the motor and a driven wheel. 29. The downhole tractor of claim 26, further including a hydraulic system adapted to move the rod between a first position in which the track assembly is in a closed position and a second position in which the track assembly is in an open position. 30. The downhole tractor of claim 26, further including a second motor adapted to rotate the screw in a first direction to cause the track assembly to move towards an open position and a second direction to cause the track assembly to move towards a closed position. 31. The downhole tractor of claim 26, wherein one of the screw and rod is adapted to move the first end of the first link in a direction generally parallel to a central axis of the tractor housing. 32. The downhole tractor of claim 26, further including a slider assembly connected to the track assembly and the lower arm, and adapted to permit relative movement between the track assembly and the lower arm. 33. The downhole tractor of claim 26, wherein the track assembly further includes a driven wheel coupled directly or indirectly to the motor. 34. The downhole tractor of claim 26, wherein the motor is coupled directly or indirectly to a second rotatable screw that is engaged with the track, whereby rotation of the second rotatable screw causes rotation of the track. 35. The downhole tractor of claim 26, wherein the motor is disposed on one of the upper or the lower arms. 36. A method of conveying an item in a well bore, comprising: providing a downhole tractor including a track assembly including a rotatable track, a motor adapted to rotate the track, a lower arm having a first end pivotally connected to a tractor housing and a second end pivotally connected to the track assembly, an upper arm having a first end pivotally connected to the tractor housing and a second end pivotally connected to the track assembly, and an actuator arm mounted to move the track assembly between open and closed positions; connecting the item to the tractor, engaging the track with an inner surface of the well bore, activating the motor, and moving the tractor along the surface. 37. The method of claim 36, further including providing a second downhole tractor. 38. The method of claim 36, further including providing a second downhole tractor spaced from the downhole tractor by a distance greater than a length of a washed out section of a well bore. 39. The method of claim 37, further wherein the second downhole tractor comprises a track assembly, the second tractor being orientated such that the track assembly of the second tractor is offset from the track assembly of the first tractor. 40. The method of claim 39, further wherein the track assembly of the second tractor is offset 90 degrees from the track assembly of the first tractor. 41. The method of claim 37, further wherein the second tractor reads the slippage of the first tractor. 42. A downhole tractor comprising: a track assembly including a plurality of idler wheels and a continuous track rotatably disposed around the idler wheels; a first motor adapted to rotate the track around the idler wheels; a lower arm having a first end pivotally connected to a tractor housing, and a second end pivotally connected to the track assembly; an upper arm having a first end pivotally connected to the tractor housing, and a second end pivotally connected to the track assembly; one of a rotatable screw and a rod; and a link assembly including a first link having a first end pivotally connected to one of the screw and the rod and a second end pivotally connected to the track assembly, and a second link having a first end pivotally connected to the track assembly and a second end pivotally mounted to the tractor housing, wherein the motor is disposed on one of the upper and lower arms. 43. The downhole tractor of claim 42, further including a second motor adapted to rotate the one of screw and rod in a first direction to cause the track assembly to move towards an open position and a second direction to cause the track assembly to move towards a closed position. 44. The downhole tractor of claim 42 wherein the second motor is disposed on one of the upper and lower arms. 45. The downhole tractor of claim 44 wherein the first and second motors are disposed on different ones of the upper and lower arms.