Power generation from a multi-lobed drilling motor

• US 5,248,896 A
• Filed: 11/09/1992
• Issued: 09/28/1993
• Est. Priority Date: 09/05/1991
• Status: Expired due to Term

• Current Assignee: Baker Hughes Incorporated (Baker Hughes Company)
• Original Assignee: Drilex Systems, Inc. (Baker Hughes Company)
• Inventors: Forrest, John
• Primary Examiner(s): Pellinen, A. D.
• Assistant Examiner(s): HOOVER, ROBERT
• Application Number:
  US07/973,602
• Time in Patent Office: 323 Days
• Field of Search: 175/94, 175/99, 175/107, 310/75 R, 290/43, 290/54, 475/176
• US Class Current: 290/1.00R
• CPC Class Codes: E21B 4/02 Fluid rotary type drives
• CPC Class Codes: F03B 13/02 Adaptations for drilling wells

Abstract

A power generation unit associated with a downhole drilling motor capable of producing sufficient rotational speeds to produce power for operating downhole devices associated with the drilling operation. The power generation unit takes advantage of the high speed precessional rotation of the rotor within the stator to drive the generator. The assembly includes a multi-lobed rotor displaceable within a stator using drilling fluid pumped therethrough. A crankshaft, mounted at one end concentric with the rotor and at its high speed take-off end concentric with the stator, transfers the rotor center precession to the shaft of the generator. In a preferred embodiment, the generator will include a socket for simply connecting downhole devices requiring electrical power.

Claims

1. A power generation unit for a downhole drilling assembly comprising:

a drilling motor including a stator and rotor wherein drilling fluid flows through said motor to drive said rotor within said stator;

generator means mounted within said unit; and

a transmission shaft for transmitting precessional revolution of said rotor relative to said stator to said generator means for generating electrical power as said rotor rotates within said stator such that the high speed precessional revolution of the rotor center is in a first direction about an axis of the stator as the transmission shaft rotates within the stator in a second direction.

2. The unit as defined in claim 1 wherein said drilling motor is a multi-lobed positive displacement drilling motor including a helical rotor displaceably driven within a helical stator mounted within a casing of said unit, said rotor rotatably displaced within said stator as drilling fluid is pumped through said drilling motor to operate a downhole drill bit.

3. The unit as defined in claim 2 wherein said rotor has one less helical lobe than said stator to facilitate displacement of said rotor within said stator.

4. The unit as defined in claim 3 wherein said rotor includes five helical lobes and said stator includes six helical lobes.

5. The unit as defined in claim 3 wherein said rotor includes nine helical lobes and said stator includes ten helical lobes.

6. The unit as defined in claim 3 wherein said rotor/stator lobe ratio is within the range of 2/3 to 12/13.

7. The unit as defined in claim 2 wherein said transmission shaft includes a crankshaft and a power take-off shaft linearly connected to said crankshaft, a first end of said power take-off shaft drivingly connected to said generator means.

8. The unit as defined in claim 7 wherein said crankshaft includes a first end connected to said power take-off shaft and axially aligned with said power take-off shaft and a central axis of said stator of said drilling motor, said crankshaft including an offset second end connected to said rotor of said drilling motor, said offset second end of said crankshaft axially aligned with a central axis of said rotor whereby said second end of said crankshaft travels along the center precessional motion of said rotor transmitting high speed rotation to drive said generator means.

9. The unit as defined in claim 8 wherein said first end of said crankshaft is supported by radial bearing supports connected to said casing.

10. The unit as defined in claim 8 wherein said generator means comprises an electrical generator mounted within said casing by radial supports such that drilling fluid may flow downhole past said generator to said drilling motor.

11. The unit as defined in claim 10 wherein said electrical generator includes connector means for connecting an auxiliary device to the electrical output of said generator.

12. A power generation unit for a downhole drilling assembly including a casing and having drilling fluid selectively pumped therethrough, said power generation unit comprising:

a multi-lobed positive displacement drilling motor including a helical stator and rotor each having a plurality of helical lobes wherein drilling fluid flows through said motor to displaceably rotate said rotor within said stator to selectively drive a downhole drilling device;

an electrical generator mounted within the casing of said unit for generating electrical power to auxiliary devices associated with the downhole drilling assembly; and

a transmission shaft for transmitting precessional revolution of said rotor relative to said stator as the drilling fluid is pumped through said drilling motor to said electrical generator thereby generating electrical power to auxiliary devices such that the high speed precessional revolution of the rotor center is in a first direction about an axis of the stator as the transmission shaft rotates within the stator in a second direction.

13. The unit as defined in claim 12 wherein said rotor has one less helical lobe than said stator to facilitate displacement of said rotor within said stator, said rotor rotatably displaced within said stator creating said precessional motion of a central axis of said rotor.

14. The unit as defined in claim 13 wherein said transmission shaft includes a crankshaft and a power take-off shaft linearly connected to said crankshaft, a first end of said power take-off shaft drivingly connected to said electrical generator.

15. The unit as defined in claim 14 wherein said crankshaft includes a first end connected to said power take-off shaft and axially aligned with said power take-off shaft and a central axis of said casing, said crankshaft including an offset second end connected to said rotor of said drilling motor, said second end of said crankshaft axially aligned with said central axis of said rotor whereby said second end of said crankshaft travels along the center precessional motion of said rotor transmitting high speed rotation to drive said electrical generator.

16. The unit as defined in claim 15 wherein said electrical generator includes connector means for connecting an auxiliary device to the electrical output of said generator.

17. In a downhole drilling device having a casing and a multi-lobed positive displacement drilling motor housed within the casing, the motor including a helical stator and rotor each having a plurality of helical lobes such that drilling fluid flowing through the motor displaceably rotates the rotor within said stator for selectively driving a downhole drilling device, the improvement comprising:

generator means mounted within said casing for generating electrical power to auxiliary devices; and

a transmission shaft coupled at a first end to said generator means and at a second end to the rotor of the drilling motor such that the high speed precessional revolution of the rotor center in a first direction about an axis of the stator as said transmission shaft rotates within the stator in a second direction is transmitted to said generator means for generating electrical power.

18. The device as defined in claim 17 wherein said transmission shaft comprises a crankshaft and a power take-off shaft linearly connected to said crankshaft, a first end of said power take-off shaft drivingly connected to said generator means.

19. The device as defined in claim 18 wherein said crankshaft includes a first end connected to said power take-off shaft and axially aligned with said power take-off shaft and a central axis of said stator of said drilling motor, said crankshaft including an offset second end connected to said rotor of said drilling motor, said offset second end of said crankshaft axially aligned with a central axis of said rotor whereby said second end of said crankshaft travels along the center precessional motion of said rotor transmitting high speed rotation to drive said generator means.