METHOD AND APPARATUS FOR MONITORING WELL PUMPING UNITS

• US 3,838,597 A
• Filed: 12/28/1971
• Issued: 10/01/1974
• Est. Priority Date: 12/28/1971
• Status: Expired due to Term

• Current Assignee: Jacque R. Stoltz, Richard C. Montgomery
• Original Assignee: Jacque R. Stoltz, Richard C. Montgomery
• Inventors: Montgomery, Richard C., Stoltz, Jacque R.
• Primary Examiner(s): Myracle, Jerry W.
• Application Number:
  US05/213,097
• Time in Patent Office: 1,008 Days
• Field of Search: 73/151,141R,141A
• US Class Current: 73/152.61
• CPC Class Codes: E21B 47/009 Monitoring of walking-beam pump systems
• CPC Class Codes: F04B 47/02 the driving mechanisms being situated at ground level F04B47/12 takes precedence
• CPC Class Codes: F04B 49/00 Control , e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
• CPC Class Codes: H02H 7/00 Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions

Abstract

Method and apparatus for monitoring the operation of a sucker rod-type pump employed in withdrawing fluids from a well. A transducer is employed to generate a signal representative of the load in the pumping unit as the rod string is reciprocated to operate a downhole pump. This signal is differentiated in order to produce a derivative function which is representative of the rate of change of the load signal. The derivative function is analyzed to detect indications of fluid pounding of the well. When a given condition of fluid pounding is encountered, a monitor function is produced which is employed to initiate action such as temporarily shutting down the pumping unit or activating an alarm. The signal from the transducer also is analyzed for a normal high load amplitude and for amplitudes which fall outside of a desired maximum-minimum load range. The invention may be implemented by hardwired or software systems.

Claims

1. In a method of monitoring the operation of a well produced by the operation of a pumping unit including a sucker rod string and means to reciprocate said rod string to produce fluid from a subterranean location, the steps comprising:

a. generating a signal representative of a changing load in said unit as said rod string is reciprocated, b. operating on said signal to produce an operating function representative of the rate of change of said signal, and c. generating a monitor function in response to said operating function reaching a specified condition.

2. The method of claim 1 further comprising the step of, prior to step (b), clipping said load signal with respect to a peak amplitude reference value, and carrying out the operation of step (b) on said clipped load signal.

3. The method of claim 1 further comprising the step of amplitude discriminating said operating function to produce a residual function thereof, accumulating said residual function, and generating said monitor function in response to said accumulated residual function reaching a specified constraint.

4. The method of claim 1 wherein said load signal is differentiated to produce a derivative of said load signal as said operating function, amplitude discriminating said operating function with respect to a discrimination value to produce a residual of said operating function comprising a plurality of pulses characteristically proportional to the amplitude differentials between the corresponding peaks of said operating function and said discrimination value, integrating said residual function, and generating said monitor function in response to said integrated residual function reaching a specified constraint.

5. The method of claim 4 wherein said pulses are proportional in duration to said amplitude differentials.

6. The method of claim 1 further comprising:

comparing said load signal with an amplitude range having an upper amplitude limit and a lower amplitude limit, and generating a monitor function in response to the amplitude of said load signal falling outside of said range.

7. The method of claim 1 further comprising:

amplitude discriminating said load signal with respect to a high amplitude discrimination value, and generating a monitor function in response to said load signal failing to reach said value within a specified frequency condition.

8. The method of claim 7 further comprising the step of, prior to step (b) of claim 1, clipping said load signal with respect to a peak amplitude reference value which is less than said high amplitude discrimination value, and carrying out the operation of step (b) on said clipped load signal.

9. The method of claim 7 further comprising:

comparing said load signal with an amplitude range having an upper amplitude limit and a lower amplitude limit, said upper amplitude limit being greater than said high amplitude discrimination value, and generating a monitor function in response to the amplitude of said load signal falling outside of said range.

10. In a system for use in monitoring the operation of a well pumping unit of the type having a rod string and means for reciprocating said rod string to operate a downhole pump, the combination comprising:

transducer means adapted to be connected to a well pumping unit of the type described for generating a signal representative of a changing load in said unit, operator means responsive to said load signal for producing an operating function representative of the rate of change of said load signal, and means responsive to said operating function for generating a monitor function upon said operating function reaching a specified condition.

11. The system of claim 10 further comprising:

discriminator means responsive to said load signal for amplitude discriminating said load signal with respect to a high amplitude discrimination value to produce a residual of said load siGnal, and timing means responsive to the residual output signal from said discriminator means for generating a second monitor function upon said load signal failing to reach said high amplitude discrimination value within a specified frequency condition.

12. The system of claim 11 further comprising:

means responsive to said first-named monitor function for disabling the operation of said timing means to generate said second-named monitor function.

13. The system of claim 11 further comprising:

comparator means responsive to said load signal for generating a readout function upon the amplitude of said load signal falling outside of the upper and lower limits of an amplitude range encompassing said high amplitude discrimination value.

14. In a system for use in monitoring the operation of a well pumping unit of the type having a rod string and means for reciprocating said rod string to operate a downhole pump, the combination comprising:

transducer means adapted to be connected to a well pumping unit of the type described for generating a signal representative of load changes in said unit, operator means responsive to said load signal for differentiating said load signal to produce an operating function which is a derivative of said load signal, means for amplitude discriminating said operating function with respect to a specified discrimination value to produce a residual function comprised of a plurality of pulses characteristically proportional to the amplitude differentials between the corresponding peaks of said operating function and said discrimination value, means responsive to the output from said amplitude discriminating means for integrating said residual function, and means responsive to the output from said integrating means for generating a monitor function upon said output reaching a specified constraint.

15. The system of claim 14 wherein said pulses are proportional in duration to said amplitude differentials.

16. The system of claim 4 further comprising:

clipper means interposed between said transducer means and operating means for clipping said load signal with respect to a peak amplitude reference value whereby said operator means differentiates said clipped load signal.

17. The system of claim 16 further comprising:

second discriminator means responsive to said load signal for amplitude discriminating said load signal with respect to a high amplitude discrimination value to produce a residual of said load signal, and timing means responsive to the residual output signal from said second amplitude discriminating means for generating a second monitor function upon said load signal failing to reach said high amplitude discrimination value within a specified frequency condition.

18. The system of claim 17 further comprising comparator means responsive to said load signal for generating a third monitor function upon the amplitude of said load signal falling outside of the upper and lower limits of an amplitude range encompassing said high amplitude discrimination value.

19. In a system for monitoring the operation of a well pumping unit of the type having a rod string and means for reciprocating said rod string to operate a downhole pump, the improvement comprising:

transducer means connected to said well pumping unit for generating a signal representative of a changing load in said unit as said rod string is reciprocated, operator means responsive to said load signal for producing an operating function representative of the rate of change of said load signal, and means responsive to said operating function for generating a monitor function upon said operating function reaching a specified condition.

20. The system of claim 19 further comprising:

discriminator means responsive to said load signal for amplitude discriminating said load signal with respect to a high amplitude discrimination value to produce a residual of said load signal, and timing means responSive to the residual output signal from said discriminator means for generating a second monitor function upon said load signal failing to reach said high amplitude discrimination value within a specified frequency condition.

21. The system of claim 20 further comprising:

means responsive to said first-named monitor function for disabling the operation of said timing means to generate said second-named monitor function.

22. The system of claim 20 further comprising:

comparator means responsive to said load signal for generating a readout function upon the amplitude of said load signal falling outside of the upper and lower limits of an amplitude range encompassing said high amplitude discrimination value.

23. In a system for monitoring the operation of a well pumping unit of the type having a rod string and means for reciprocating said rod string to operate a downhole pump, the improvement comprising:

transducer means connected to said well pumping unit for generating a signal representative of load changes in said unit as said rod string is reciprocated, operator means responsive to said load signal for differentiating said load signal to produce an operating function which is a derivative of said load signal, means for amplitude discriminating said operating function with respect to a specified discrimination value to produce a residual function comprised of a plurality of pulses characteristically proportional to the amplitude differentials between the corresponding peaks of said operating function and said discrimination value, means responsive to the output from said amplitude discriminating means for integrating said residual function, and means responsive to the output from said integrating means for generating a monitor function upon said output reaching a specified constraint.

24. The system of claim 23 wherein said pulses are proportional in duration to said amplitude differentials.

25. The system of claim 23 further comprising:

clipper means interposed between said transducer means and operating means for clipping said load signal with respect to a peak amplitude reference value whereby said operator means differentiates said clipped load signal.

26. The system of claim 25 further comprising:

second discriminator means responsive to said load signal for amplitude discriminating said load signal with respect to a high amplitude discrimination value to produce a residual of said load signal, and timing means responsive to the residual output signal from said second amplitude discriminating means for generating a second monitor function upon said load signal failing to reach said high amplitude discrimination value within a specified frequency condition.

27. The system of claim 26 further comprising comparator means responsive to said load signal for generating a third monitor function upon the amplitude of said load signal falling outside of the upper and lower limits of an amplitude range encompassing said high amplitude discrimination value.