Bearing fault detection for surface pumping units

Patent metadata

Field	Value
Publication number	US-10794173-B2
Application number	US-201715487106-A
Country	US
Kind code	B2
Filing date	Apr 13, 2017
Priority date	Apr 13, 2017
Publication date	Oct 6, 2020
Grant date	Oct 6, 2020

Abstract

Methods and apparatus for operating a rod pumping unit for a wellbore are provided. One example method includes measuring vibration data in the time domain using at least one sensor coupled to a housing for a moving component of the rod pumping unit; converting the vibration data in the time domain to vibration data in the frequency domain; determining that: (1) at least one frequency component of the frequency-domain vibration data in a first frequency band has a power above a first threshold; or (2) a number of frequency components of the frequency-domain vibration data in a second frequency band having power above a second threshold is above a third threshold; and outputting an indication based on the determination.

First claim

The invention claimed is:

1. A method for operating a rod pumping unit for a wellbore, comprising:
measuring vibration data in the time domain using at least one sensor attached to a wrist pin housing at least partially enclosing a wrist pin bearing of the rod pumping unit;
converting the vibration data in the time domain to vibration data in the frequency domain;
determining that:
at least one frequency component of the frequency-domain vibration data in a first frequency band has a power above a first threshold; or
a number of frequency components of the frequency-domain vibration data in a second frequency band having power above a second threshold is above a third threshold, wherein at least one of the at least one frequency component in the first frequency band or the frequency components in the second frequency band are characteristic of the wrist pin bearing; and

taking an action related to operating the rod pumping unit, based on the determination, wherein taking the action comprises causing the rod pumping unit to cease pumping.

2. The method of claim 1 , wherein the second frequency band comprises higher frequencies than those in the first frequency band.

3. The method of claim 2 , wherein the second frequency band has frequencies greater than about 6 Hz and wherein the first frequency band has frequencies less than about 6 Hz.

4. The method of claim 1 , further comprising adjusting at least one of the first threshold or a width of the first frequency band, wherein the adjusting is based on at least one of dimensions of the wrist pin bearing or dimensions of the wrist pin housing.

5. The method of claim 1 , further comprising adjusting at least one of the second threshold, the third threshold, or a width of the second frequency band.

6. The method of claim 1 , wherein the converting comprises using a fast Fourier transform (FFT).

7. The method of claim 1 , wherein the at least one sensor comprises at least one accelerometer and wherein the first threshold represents a g-force value.

8. The method of claim 1 , wherein:
the determination that the at least one frequency component in the first frequency band has a power above the first threshold indicates an onset of excessive wear or mechanical damage to the wrist pin bearing; and
the determination that the number of frequency components in the second frequency band is above the third threshold indicates impending failure of the wrist pin bearing.

9. The method of claim 1 , further comprising:
powering down the at least one sensor after the measuring for an interval; and
periodically powering on the at least one sensor to perform at least the measuring.

10. The method of claim 1 , further comprising wirelessly transmitting at least one of the time-domain or the frequency-domain vibration data to a processing system.

11. The method of claim 1 , wherein the third threshold is a positive integer.

12. The method of claim 1 , wherein the at least one sensor is configured to be magnetically coupled to the wrist pin housing at least partially enclosing the wrist pin bearing in the rod pumping unit.

13. The method of claim 1 , wherein the determination that the at least one frequency component in the second frequency band has the power above the third threshold indicates an onset of excessive wear or mechanical damage to the wrist pin bearing.

14. An apparatus for monitoring a wrist pin bearing in a rod pumping unit for a wellbore, comprising:
at least one sensor configured to measure vibration data associated with the wrist pin bearing in the time domain;
at least one processor electrically coupled to the sensor and configured to:
convert the vibration data in the time domain to vibration data in the frequency domain;
determine that:
at least one frequency component of the frequency-domain vibration data in a first frequency band has a power above a first threshold; or
a number of frequency components of the frequency-domain vibration data in a second frequency band having power above a second threshold is above a third threshold, wherein at least one of the at least one frequency component in the first frequency band or the frequency components in the second frequency band are characteristic of the wrist pin bearing; and

cause taking an action, based on the determination, wherein taking the action comprises at least one of causing the rod pumping unit to cease pumping, displaying a visual indication for an operator of the rod pumping unit, or sounding an audible indication for the operator of the rod pumping unit; and

a housing containing the at least one sensor and the at least one processor, wherein the housing is configured to be bolted onto or magnetically coupled to a wrist pin housing at least partially enclosing the wrist pin bearing in the rod pumping unit.

15. The apparatus of claim 14 , further comprising an input/output interface configured for wireless communications to wirelessly transmit at least one of the time-domain or the frequency-domain vibration data to a wireless receiver.

16. The apparatus of claim 14 , wherein the at least one sensor comprises at least one accelerometer and wherein the first threshold represents a g-force value.

17. The apparatus of claim 14 , further comprising at least one of a visual indicator or an audible indicator configured to display the visual indication or sound the audible indication for the operator of the rod pumping unit.

18. The apparatus of claim 14 , wherein the at least one processor is further configured to adjust at least one of the first threshold or a width of the first frequency band, wherein the adjustment is based on at least one of dimensions of the wrist pin bearing or dimensions of the wrist pin housing.

19. The apparatus of claim 14 , wherein the determination that the at least one frequency component in the second frequency band has the power above the third threshold indicates an onset of excessive wear or mechanical damage to the wrist pin bearing.

20. A non-transitory computer-readable medium for operating a rod pumping unit for a wellbore, comprising instructions executable by one or more processors to:
receive vibration data in the time domain from at least one sensor attached to a wrist pin housing at least partially enclosing a wrist pin bearing of the rod pumping unit;
convert the vibration data in the time domain to vibration data in the frequency domain;
determine that:
at least one frequency component of the frequency-domain vibration data in a first frequency band has a power above a first threshold; or
a number of frequency components of the frequency-domain vibration data in a second frequency band having power above a second threshold is above a third threshold, wherein at least one of the at least one frequency component in the first frequency band or the frequency components in the second frequency band are characteristic of the wrist pin bearing; and

control operation of the rod pumping unit based on the determination, wherein controlling the operation comprises causing the rod pumping unit to cease pumping.

21. The non-transitory computer-readable medium of claim 20 , wherein the instructions are executable by the one or more processors to adjust a width of the first frequency band, wherein the adjusting is based on at least one of dimensions of the wrist pin bearing or dimensions of the wrist pin housing.

22. The non-transitory computer-readable medium of claim 20 , wherein the determination that the at leas

Assignees

• Weatherford Tech Holdings Llc

Inventors

• Ebrahimi Behrouz S
• Lembcke Jeffrey John
• Robison Clark E

Classifications

• E21B43/127

  Adaptations of walking-beam pump systems · CPC title

• E21B41/00

  Equipment or details not covered by groups E21B15/00 - E21B40/00 · CPC title

• F04B47/02

  the driving mechanisms being situated at ground level (F04B47/12 takes precedence) · CPC title

• E21B47/009 Primary

  Monitoring of walking-beam pump systems · CPC title

• G01M13/045 Primary

  Acoustic or vibration analysis · CPC title