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US4034808A
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Method for pump-off detection
Assignee: Shell USA Inc
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Filing: 1976-09-20
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Granted: 1977-07-12
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Expires: 1996-09-20
Abstract
Abstract A method and apparatus for measuring the energy input to the rod string of a well pumping unit in real time wherein the load on the rod string is multiplied by the velocity of the rod string and the result integrated over at least a portion of the pump stroke. The change in the energy input to the well is used to determine when the well has pumped-off.
Inventors
- 👤 Maurice M. Patterson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 17:02
CPC Classifications
G; G01; G01L; G01L3/00; G01L3/24; G01L3/247; E; E21; E21B; E21B47/00; E21B47/008; E21B47/009; F; F04; F04B; F04B49/00; F04B49/02
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
51 words
A method for measuring the energy input to the rod string in a rod pumping unit comprising: measuring the load on the rod; obtaining the velocity of the rod; and multiplying the load times the velocity and integrating the product to obtain the energy input for each stroke in real time.
Claim 2
Independent Claim
51 words
A method for measuring the energy input to the rod string in a rod pumping unit comprising: measuring the load on the rod; obtaining the velocity of the rod; and multiplying the load times the velocity and integrating the product to obtain the energy input for each stroke in real time.
Claim 3
Dependent Claim
23 words
The method of claim 1 wherein the velocity is obtained by measuring the displacement of the rod and determining the first derivative thereof.
Claim 4
Dependent Claim
27 words
The method of claim 1 wherein the velocity is approximated using a sine wave having a period equal to the time required for a complete pump stroke.
Claim 5
Dependent Claim
14 words
The method of claim 3 wherein energy input for only negative velocity is measured.
Claim 6
Dependent Claim
18 words
The method of claim 4 wherein only a portion of the energy input for negative velocity is measured.
Claim 7
Independent Claim
95 words
A method for determining when a rod pumped well has pumped-off comprising: measuring the load on the rod string and producing an analog electrical signal; simulating the velocity of the rod string by a sine wave electrical signal having a period equal to the time required for the pump to make a complete stroke; multiplying the load signal by the simulated velocity; integrating the negative values of said multiplication to obtain the negative energy input to the rod string; and comparing said negative energy input with predetermined value to determine when said well is pumped-off.
Claim 8
Independent Claim
95 words
A method for determining when a rod pumped well has pumped-off comprising: measuring the load on the rod string and producing an analog electrical signal; simulating the velocity of the rod string by a sine wave electrical signal having a period equal to the time required for the pump to make a complete stroke; multiplying the load signal by the simulated velocity; integrating the negative values of said multiplication to obtain the negative energy input to the rod string; and comparing said negative energy input with predetermined value to determine when said well is pumped-off.
Claim 9
Dependent Claim
16 words
The method of claim 6 wherein only a selected portion of said negative values are integrated.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-07-11 | 1981-01-10 | 1981-07-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-07-11 | 1985-01-10 | 1985-07-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-07-11 | 1989-01-10 | 1989-07-12 | $7700.00 | Window Closed / Lapsed |