Positive displacement motor with radially constrained rotor catch

Patent metadata

Field	Value
Publication number	US-9982485-B2
Application number	US-201615342924-A
Country	US
Kind code	B2
Filing date	Nov 3, 2016
Priority date	Nov 18, 2011
Publication date	May 29, 2018
Grant date	May 29, 2018

Abstract

Techniques relate to a moving cavity motor or pump, such as a mud motor, including a rotor, a stator, and one or more apparatus for constraining (i.e., controlling or limiting) the movement of the rotor relative to the stator, where the apparatus for constraining is operable with the rotor catch. The motor may include a top sub, power section having a progressive cavity motor with a stator and rotor, a rotor catch, and an apparatus between a proximal and distal end of the rotor catch shaft. The apparatus may constrain the radial and/or tangential movement of the rotor catch shaft and the rotor.

First claim

What is claimed:

1. A mud motor assembly, comprising:
a top sub comprising a shoulder having a first inner diameter proximate a distal end of the top sub;
a power section comprising a progressive cavity motor comprising a stator and a rotor configured to rotate when a drilling fluid is passed through the motor, the stator and rotor each having a proximal end and a distal end, wherein a proximal end of the power section is coupled to the distal end of the top sub;
a rotor catch comprising a shaft having a proximal end and a distal end, and rotating transmission of the rotor motion;
wherein the distal end of the shaft is coupled directly or indirectly to a proximal end of the rotor;
wherein the shaft extends into the top sub a distance past the shoulder, wherein at least a portion of the shaft extending past the shoulder has an outer diameter less than the first inner diameter of the shoulder; and
wherein the proximal end of the shaft has an effective outer diameter greater than the first inner diameter and is spaced apart from the shoulder, such that the shaft does not transmit an axial force to the shoulder unless a part of the motor assembly or a drill string attached thereto breaks, and/or the proximal end of the shaft is coupled to a rotor catch assembly comprising one or more components having an effective outer diameter greater than the first inner diameter, the rotor catch assembly being spaced axially apart from the shoulder such that the shaft does not transmit an axial force to the shoulder unless a part of the motor assembly or a drill string attached thereto breaks; and

at least one apparatus disposed intermediate the proximal and distal end of the rotor catch shaft, the at least one apparatus configured to constrain the radial and/or tangential movement of the rotor catch shaft and by transmission via the shaft to constrain the radial and/or tangential movement of the rotor.

2. A drilling assembly, comprising:
a mud motor assembly comprising a top sub and a power section;
the top sub comprising a shoulder having a first inner diameter proximate a distal end of the top sub;
the power section comprising a progressive cavity motor comprising a stator and a rotor configured to rotate when a drilling fluid is passed through the motor, the stator and rotor each having a proximal end and a distal end, wherein the proximal end of the stator is coupled to the distal end of the top sub;
a rotor catch comprising a shaft having a proximal end and a distal end, and rotating via transmission of the rotor motion;
wherein the distal end of the shaft is coupled directly or indirectly to a proximal end of the rotor;
wherein the shaft extends into the top sub a distance past the shoulder, wherein at least a portion of the shaft extends past the shoulder and has an outer diameter less than the first inner diameter of the shoulder;
wherein the proximal end of the shaft has an effective outer diameter greater than the first inner diameter and/or is coupled to a rotor catch assembly comprising one or more components having an effective outer diameter greater than the first inner diameter;

at least one apparatus disposed intermediate the proximal and distal end of the rotor catch shaft, the at least one apparatus configured to constrain the radial and/or tangential movement of the rotor catch shaft and by transmission via the shaft to constrain the radial and/or tangential movement of the rotor, wherein the at least one apparatus is disposed intermediate the shoulder and the distal end of the shaft;
a motor output shaft directly or indirectly coupled to the distal end of the rotor; and
a drill bit directly or indirectly coupled to a distal end of the motor output shaft.

3. The assembly of claim 1 , wherein the at least one apparatus is disposed intermediate the shoulder and the distal end of the shaft.

4. The assembly of claim 1 , wherein the at least one apparatus is operative with at least one of an inner surface of the top sub and an inner surface of the power section.

5. The assembly of claim 1 , wherein an operative area of the at least one apparatus is concentric with an operative area of the rotor/stator pair.

6. The assembly of claim 1 , wherein the at least one apparatus limits the movement of a geometric center of the rotor to a predetermined path.

7. The assembly of claim 1 , wherein a surface of the stator is made of a flexible material to permit a seal to form between contacting surfaces of the rotor and the stator, and wherein the at least one apparatus limits the deflection or compression of the flexible material to less than 0.64 mm.

8. The mud motor assembly of claim 1 , wherein the stator has a contact surface formed from a rigid material, the rigid material including at least one of a metal, a composite, a ceramic, a hard plastic, or PCD.

9. The assembly of claim 8 , wherein the stator has a profile including peak sections and valley sections, and wherein the peak sections comprise the rigid material and the valley sections comprise a resilient material.

10. The assembly of claim 8 , wherein the rotor comprises a contact surface formed from a rigid material.

11. The assembly of claim 8 , wherein the rotor comprises a layer comprising a resilient material and a contact surface layer comprising a rigid material that is the same as the rigid material of the stator.

12. The assembly of claim 8 , wherein the contact surface of the rigid material of the stator or a rigid material of the rotor are coated or treated to reduce at least one of friction and wear, the rigid material of the rotor being the same as the rigid material of the stator.

13. The assembly of claim 1 , wherein the at least one apparatus comprises one or more of:
a. a bearing assembly for controlling or limiting the movement of the shaft and thereby controlling or limiting the movement of the rotor within the stator;
b. a wheel assembly for controlling or limiting the movement of the shaft and thereby controlling or limiting the movement of the rotor within the stator;
c. a fixed insert for controlling or limiting the movement of the shaft and thereby controlling or limiting the movement of the rotor within the stator;
d. a rotatable insert for controlling or limiting the movement of the shaft and thereby controlling or limiting the movement of the rotor within the stator; and
e. a precession device for controlling or limiting the movement of the shaft and thereby controlling or limiting the movement of the rotor within the stator.

14. The assembly of claim 13 , wherein the wheel assembly comprises a wheel mounted on a shaft of the rotor, the wheel being configured to run around an inner surface of the stator.

15. The assembly of claim 13 , wherein the wheel assembly comprises a wheel mounted on a shaft of the stator, the wheel being configured to permit the rotor to run around an outer surface of the stator.

16. The assembly of claim 15 , wherein an outside diameter of the wheel is equal to a diameter of an inner surface of the stator minus twice a predetermined maximum offset of the rotor from its geometric centerline.

17. The assembly of claim 15 , wherein an outside diameter of the wheel is equal to a diameter of an inner surface of the rotor minus twice a predetermined maximum offset of the rotor from its geometric centerline.

18. The assembly of claim 13 , wherein the fixed insert is mounted within an outer member of the rotor-stator pair and has a central aperture through which a shaft of an inner member of the rotor-stator pair can pass, the diameter of the cent

Assignees

• Smith International

Inventors

• Murray William
• Underwood Lance D
• Cariveau Peter Thomas
• Jarvis Brian P
• Wilcox Nigel
• Williams Brian
• Downton Geoffrey
• Lee Lawrence
• Onodera Shun'Etsu
• Alvarado Daniel
• Pushkarev Maxim
• Tunc Gokturk
• Plop Andrei

Classifications

• F03C2/08

  of intermeshing-engagement type, i.e. with engagement of co- operating members similar to that of toothed gearing · CPC title

• F01C21/08

  Rotary pistons (reciprocating pistons in general F16J) · CPC title

• E21B4/02 Primary

  Fluid rotary type drives · CPC title

• F04C13/008

  Pumps for submersible use, i.e. down-hole pumping · CPC title

• F01C21/104

  Stators; Members defining the outer boundaries of the working chamber · CPC title