Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
(OP)
We need to measure the Electric Power consumption (kW power intake) of electric motors driving Pump Jacks in oil wells.
I am pretty sure this requires the use of a special type of meter due to the cyclic nature of the pump operation (along its cycle it goes from high to low % Load values). Something like the Dranetz Demand Analyzer (e.g. take readings over a certain time interval).
Common hand-held, single digital output devices (e.g volts, amps, kw etc) won't do for this particular application.
I have seen this issue documented in a few papers (e.g. from the Society of Petroleum Engineers -SPE-).
I would appreciate if someone can indicate specific references regarding applicable standards for this measurement (like API, IEEE, etc).
Comments and suggestions on this issue will also be greatly appreciated.
I am pretty sure this requires the use of a special type of meter due to the cyclic nature of the pump operation (along its cycle it goes from high to low % Load values). Something like the Dranetz Demand Analyzer (e.g. take readings over a certain time interval).
Common hand-held, single digital output devices (e.g volts, amps, kw etc) won't do for this particular application.
I have seen this issue documented in a few papers (e.g. from the Society of Petroleum Engineers -SPE-).
I would appreciate if someone can indicate specific references regarding applicable standards for this measurement (like API, IEEE, etc).
Comments and suggestions on this issue will also be greatly appreciated.





RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
1) top
2) mid-way down
3) bottom
4) mid-way up
For long-term power consumption over specific times, we have had the utility company connect a recording meter at the service. We also had a 3PH Fluke recording meter we would use as well.
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
Keith Cress
kcress - http://www.flaminsystems.com
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
Look on the utility meter for the kH factor. This is the watt hours for one revolution of the disk. Count and time the disk revolutions for 5 or 10 pump-jack cycles. Now you have the WHr consumption over a measured time period. Do the math. Don't forget to factor in the meter multiplier if applicable and divide by 1000 to get KWHrs.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
Keith Cress
kcress - http://www.flaminsystems.com
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
I would expect two cycles per stroke in the electric demand if the counter balance is matched correctly with the down hole rod. If not perfectly aligned, and they never are, one of the two cycles will have a greater demand than the other. The problem lies in that several of these pump jacks will sync themselves and cause some very noticable voltage fluxuations that other customers will notice.
If the jack is greatly unbalanced, the two single phase Watt meter method will not work well, as part of the cycle will be generation back into the power system. This is confusing and I have seen arguments because the calculations don't work as expected. I would recommemnd a recording meter over the whole stroke to best determine the consumption.
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
http://www.ebay.ca/itm/ABB-Asea-Brown-Boveri-Type-...
I previously used kH. It should have been Kh
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
Keith Cress
kcress - http://www.flaminsystems.com
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
Ya got me Keith!!
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
cranky108: I think you are right.
The "recording" type meter is the way to go, there are some that in fact go longer than just the full cycle of the pump.
The problem with the Pump Jack is the high variability of the % Load on the motor. Just the opening of the traveling valve introduces a huge "point" variation.
There are a number of 'recording meter'types (under the general category of "demand analyzer") and they are expensive. Some even offer "leasing" the instrument.
Like I mentioned, the need for this type of instrument has been described at various times in literature (e.g. Society of Petroleum Engineers).
For our purpose, optimizing energy use, determining the % Load profile of the motor is fundamental (e.g. amount of time and intervals it operates 'underloaded' and by how much).
What I have not been able to find, and if anyone knows anyghing about it I'd appreciate it, is specific information on applicable standards (API, IEEE, NEMA etc.) for the task of determining/measuring Power intake [kW] in a Pump Jack type rig.
Again thanks to all.
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
We've told you how to accurately measure "the kW" of your pump motor.
You now speculate that due to the variability of the motor load. You must use an "expensive" special meter. You do not. Any junk kWhr meter will do a better job than you would ever need of measuring the average kW power usage of your pump motor.
This begs the question, is your question wrong? Are you really needing something else? What exactly are you needing this 'power' measurement for? Is it only for adjusting the counter-weights?
Keith Cress
kcress - http://www.flaminsystems.com
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
How cheap do you want this power meter to be? AccuEnergy makes some cheap meters that have tons of features.
http://www.accuenergy.com/?discography=acuvim-l-se...
http://www.powermeterstore.com/p8153/acuvim_al.php
Throw some CT's and PT's at this meter and you can easily have a permanently installed meter for <$500 in parts. You can go around to your pump jacks and log the kWh of each site and then reset the meter to record for the next session. Heck, the meter even has RS-485 communications so you can set-up automatic data logging if you wanted. If you don't like that meter, they have fancier ones that cost more of course.
If you want to try and determine some kind of pump jack efficiency rating then you'd have to measure some other parameters from the pump jack outside of the motor energy usage, such as amount of material pumped, speed being used and valve positions. Feed it all back to a computer and log the data to see what operating point gives the most material pumped per kWh used.
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
I suggest you call one of these companies and speak with a technical representative. They will know the limitations of their meters. Typically, though, the sample rate is far higher than what you need.
Disclosure: I am a former employee and currently am a consultant for Kele.
Best to you,
Goober Dave
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RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
It would be very helpful indeed if you can state WHY you wish to measure and record - what? Power? Energy? Peak demand? In other words, what is your end goal? Are you trying to correctly size the drive motor and its supply conductors? Or, as itsmoked asked, are you trying to adjust the counterweights so the heights of the two load 'scallops' on your power versus time trace are identical? Or maybe add customized power factor corrective elements to each jack?
Carl
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
One final post regarding some of the answers.
There seem to be some confusion as to the original question. Some seem to not understand whether I want to measure "Power" or "Energy". Others indicated that although I want to measure "Power" (as in [kW]) I should be measuring "Energy" (as in [kWh]) instead.
The original question clearly states that the objective is to measure "Power" (as in [kW], power intake to the loaded motor, for instance).
As to the reason for wanting to measure that, I suggest reading (among the many references in literature) the Fact Sheet "Determining Electric Motor Load and Efficiency" from the Motor Challenge Program of the US Dept. of Energy.
The Power Intake of a loaded motor can be measured directly or calculated as: Pi = f (V,I,PF) where Pi is the input Power in [kW].
Once Pi is obtained, the "% Load" (output power as % of rated power) of the motor is calculated as: (Pi/Pir)x 100 where Pir is the input Power at full rated load.
Once the % Load is known, the Efficiency at which the motor is operating can be estimated.
That and the difference between "% electric load" and "% mechanical load" (e.g. in the motor shaft) are also well explained in the Fact Sheet.
HOWEVER, directly measuring the Power intake or the variables needed to calculate it (V, I and PF) in the case of a highly variable load like the Pump Jack (as indicated in my original question) requires a particular type of instrument, one capable of recording the values of the variables vs. Time (my original question mentions one such instrument, there are many in the market).
In loads of this type, the I and PF are varying constantly and rapidly. Hence the need for this particular type of instrument.
There are MANY articles and literature references about this. One that I think covers the subject rather well is a paper from the Society of Petroleum Engineers (paper SPE 16363: Electrical Savings in Oil Production by J.E. Bullock, Pacific Gas & Electric Co.. Presented at the Society's regional meeting in California in 1987). Regarding the proper equipment for these measurements in the particular case of Pump Jacks, the paper indicates that meters whose output is instantaneous values of the measured parameters are "not suited for measuring pumping unit motors" due to the cyclic nature of their operation (e.g. highly variable % Load condition).
The foregoing I hope clears that the objective is to measure POWER intake of the loaded motor (e.g. [kW] (to be used in determining % Load and Efficiency of the motor) and that a particular type of instrument is required in the case of the Pump Jack and similar types of loads.
Should anybody question any of that, I'd suggest taking the case up with the authors and/or organizations providing the material. I am merely a reader/user of it.
About the reason for wanting to measure/calculate those parameters:
This is also covered in the two references mentioned (and there is a score of others...). There are a number of reasons, all having to do with Optimizing Energy Use in Oil Production: advisability/convenience of replacing a motor with one of higher Efficiency, installing any of various options for energy savings, determine which pump jacks are the better candidates for any of these actions... etc etc.
That said, let me go back to the ORIGINAL QUESTION:
Does anyone know of any specific STANDARDS from any reputable organization or professional society (e.g. IEEE, API, SPE etc etc.) relevant to the case of pump jacks, referring to the measurement of the Power intake of electric motors (or their Efficiency) in the specific case of pump jacks or similar highly variable loads ?? (e.g. type of instrument, minimun length of recording time or any other aspect of this task).
(NOTE that I have made reference to publications, articles and papers but NOT to Standards. That's what I’m trying to find out).
Thanks and best regards to all.
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
There may be standards for measurement of power in protective relaying systems -- those would be much faster than you need as well, I would think.
Using power measurements to diagnose degradations in motor drivepower systems: a case study of oilfield pump jacks
Microprocessor based fast active power measurement
If it were me, I would just get the Dranetz machine, or one of the LabView apps. They are expensive...
Best to you,
Goober Dave
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RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
If you want the most accurate measurements for the power put into the well verse the oil volume returned then I repeat:
The most accurate method is not fancy instantaneous instruments it is merely a standard WattHour ENERGY meter. Energy divided by time is POWER. The standard meter gives the REAL POWER. That's the power that you pay for. It's the power that lifts the oil. The more time the energy is measured over, the more accurate the measurement, the more accurate the resulting power measurement. Standard watthour meters are fully capable of tracking the power excursions of a sucker pump motor. They border on the trivial, as far as watthour meters are concerned.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
I suggest an exercise to get a feeling for motor efficiency on pump jack service.
Take the published efficiency curves of several suitable motors. As well as different efficiency rated motors, use the curves from motors that are one or two sizes over-sized.
Estimate the work curve of the pump jack cycle.
Set up a spread sheet to calculate the efficiencies of the motors throughout the pumping cycle and then calculate the overall efficiency of each motor.
It may be interesting to consider the cases where the counter weights are more than or less than the optimum mass.
Over the years I have found this type of exercise valuable to develop a real "feel" for an effect, and an aid in developing personal "Rules of Thumb". I seldom do it more than once. The first time I did power factor correction, the calculations took several hours. The second time the calculations took several minutes. But I have never regretted the time spent on the first calculations.
This exercise will probably take several hours, but at the end of the day you may have a better feel for pump jack motor efficiencies than most people.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
I have no standards. Don't beat me up for responding.. I wanted to point out a potentially very tricky aspect when using digital instrument in the presence of highly varying loads (potentially aggravated by resonant torsional swings). If there is a period when the oscillation causes the real power to reverse, then during that period it contributes to increasing the integral of apparent power while decreasing the integral of real power. Thus any kind of "power factor" calculated as a time-averaged real power over a time-averaged apparent power would be meaningless (at least much different than anyone would expect). Example was discussed here:
thread237-249262: Low power factor, recip pump
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(2B)+(2B)' ?
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
The efficiency of the motor varies as the load changes. Coming up with some type of time averaged load and efficiency to compare 2 motors won't give you any true answers.
There have been multiple posts suggesting to use kWh and divide by time. Those answers were all 100% exactly correct since that calculation is the number you've now posted that you wanted 3 times. It's turned into listening to a skipping record here...
I don't think the authors of the papers you're reading would appreciate being blamed for your lack of understanding.
On another note, those steps to calculate the percentage load on the motor are good for nothing more than a rough estimate. It completely skips the part where the motor efficiency has changed once the load changed. Then that paper also seems to imply that you first calculate the percent load on the motor using the motor rated efficiency and then use that answer to calculate the efficiency of the motor. I'll save you the bother of doing any calculations. The efficiency answer will be the motor full load efficiency. You'll need a different method if you want a useful answer.
If you want to figure out the efficiency of your pump jack then use gallons or litres of oil pumped per kWh of energy used.
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
Some of the problems you will run into with pump jacks, is some operators use old or rewound motors, and even if they are in good shape, the nameplates may be unreadable because of age or paint or both. So even if you think you know the size of the motor, it may not be so.
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
However, the abstract to the paper I cited in my last post indicates that something more is needed for the OP's purpose perhaps:
I didn't want to plunk down $13 for the whole paper -- it's the OP's pump jack issue, not mine. Note that I also recommended measuring with a simple device earlier in this thread. The energy portion would be fine; therefore, the average power will be fine as well. "Spectrum analysis of instantaneous power" is certainly not in my game. Thoughts?
Best to you,
Goober Dave
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RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
RE: Electric Motors driving Sucker Rod Pumps (oil pump jacks): correctly measure their Power consumption
Best to you,
Goober Dave
Haven't see the forum policies? Do so now: Forum Policies