DRILLING MOTOR WITH A LOCKING COLLET SLEEVE STABILIZER

• US 20110240370A1
• Filed: 03/30/2011
• Published: 10/06/2011
• Est. Priority Date: 04/01/2010
• Status: Active Grant

• Current Assignee: National Oilwell Varco LP (NOV, Inc.)
• Original Assignee: National Oilwell Varco LP (NOV, Inc.)
• Inventors: Melhem, Nazeeh, Shwets, Peter
• Granted Patent: US 8,770,318 B2
• Time in Patent Office: Days
• US Class Current: 175/92
• CPC Class Codes: E21B 17/1078 Stabilisers or centralisers for casing, tubing or drill pipes devices for off-center positioning E21B17/10; E21B17/1007 - E21B17/1064 take precedence
• CPC Class Codes: E21B 4/02 Fluid rotary type drives

Abstract

A threaded sleeve stabilizer spans an upper stator connection in a mud driven drilling motor used for borehole drilling. A number of collets are loaded in compression between the stator and the housing of the motor, and are held in compression by a threaded connection.

Claims

1. A locking sleeve stabilizer for a downhole drilling motor comprising:

a plurality of collets arrangable in a generally cylindrical ring and loadable into compression by a threaded sleeve for locking a stator of the drilling motor to a housing of the drilling motor, providing enhanced stiffness of a connection between the stator and the housing.

2. The locking sleeve stabilizer of claim 1 wherein the plurality of collets are formed from a different material than the material of the threaded sleeve.

3. The locking sleeve stabilizer of claim 1 wherein a bending strength of a threaded connection at a top end of the stator is greater than a bending strength of the housing thereby providing additional stiffness to the threaded connection while limiting drill string deflection at by effectively adding stiffness to the threaded connection between the housing and the stator.

4. The locking sleeve stabilizer of claim 1 wherein the threaded sleeve connects to the outside diameter of the housing.

5. The locking sleeve stabilizer of claim 4 wherein the threaded sleeve is located axially over the threaded connection between the housing and a stator.

6. The locking sleeve stabilizer of claim 1 wherein a lower end of the threaded sleeve has an internal bore that is located along an outside of a stator tube and below a stator box of the stator.

7. The locking sleeve stabilizer of claim 6 wherein an annulus is created between an internal bore of the threaded sleeve and an OD of the stator which provides a chamber to receive the plurality of collets.

8. The locking sleeve stabilizer of claim 7 wherein either the outer surface of the plurality of collets, or an inner surface within a bore of the threaded sleeve, or both, are tapered such that an axial force on the bottom of the plurality of collets cause the plurality of collets to be wedged between an outside of the stator and an inside of the threaded sleeve.

9. The locking sleeve stabilizer of claim 1 wherein the plurality of collets have an internal wedge configuration to secure the internal components.

10. The locking sleeve stabilizer of claim 9 wherein the internal wedge configuration allows the plurality of collets to remain in proper position during operation to maintain a relative position within the motor during operation.

11. The locking sleeve stabilizer of claim 1 wherein the plurality of collets are made of a material having a lower modulus of elasticity than the housing.

12. The locking sleeve stabilizer of claim 1 wherein the plurality of collets have the same modulus of elasticity of the housing, but have a significantly lower hardness than the housing.

13. The locking sleeve stabilizer of claim 1 wherein a lower end of the threaded sleeve has a threaded box located below the plurality of collets into which is threaded a locking sleeve which, when makeup torque has been applied, contacts the plurality of collets and provides axial force to wedge the plurality of collets upward between the threaded sleeve and the stator.

14. The locking sleeve stabilizer of claim 13 wherein the wedged plurality of collets firmly secure a lower end of the threaded sleeve to the stator while an upper end of the threaded sleeve is secured to the housing through the threaded connection therebetween to effectively add stiffness to the connection between the housing and stator.

15. The locking sleeve stabilizer of claim 1 wherein an outer diameter of the threaded sleeve is closely sized to a diameter of the borehole and thereby limiting deflection of a bottom hole assembly and providing additional stability to the connection between the housing and stator during drilling operations.

16. The locking sleeve stabilizer of claim 1 wherein a wedge arrangement formed from the plurality of collets is disposed intermediate the stator and the housing.

17. The locking sleeve stabilizer of claim 16 wherein the wedge arrangement may include one or more of the plurality of collets.

18. The locking sleeve stabilizer of claim 1 wherein each of the plurality of collets is distinct from each other so as to be individually fitted into the motor so as to be independent of each other.

19. The locking sleeve stabilizer of claim 1 wherein the plurality of collets have generally the same width.

20. The locking sleeve stabilizer of claim 1 wherein the plurality of collets may be of varying widths to accommodate assembly.

21. A downhole motor adapted for drilling boreholes into the earth comprising a compression loaded retention device, the retention device comprising a plurality of separate collets that are loaded in compression between a stator and a housing of the motor, and are held in compression by a threaded connection wherein the plurality of separate collets maintain the compressive loading thereof at a thrust bearing end of a driveshaft assembly for the motor.