AMPS CHART TROUBLE SHOOTING ESP Oil Well

AMPS Chart

1. 电流卡片分析和故障诊断
Daqing Powerlift Pump Industry

2. One of the most valuable tools in trouble shooting
downhole problems is the amp chart. Many
conditions can be properly diagnosed allowing
corrective action to be taken without the need to
pull the equipment or, if the downhole unit must be
pulled, a better decision may be made as to what
must be done when re-running the replacement
unit.
The amp chart is not the only diagnostic tool which
the engineer should use but it is one of the most
important since it can show what happened to the
unit over time.

3. The ammeter is an analog device which is mounted
on most switchboards. It is mechanically driven so
does not need any voltage to operate its clock.
This allows the meter to run even when no voltage
is supplied to the switchboard as in a power
outage.

4. The ammeter itself has a round recording chart with
a pen which moves in and out in proportion to the
amount of current which the meter senses.
All Ammeters operate on 0 to 5 amps with 5 amps
being full scale.

5. Trouble Shooting
In order to make the motor current compatible with
the ammeter, one leg of the switchboard power
cable is fed through a current transformer (CT).
(Actually all 3 legs pass through a CT but only one
is monitored by the amp chart recorder). The
standard CT has two selectable ratios -- 200:5 and
150:5 although other CT's are common such as
300:5, 75:5, 100:5, etc. In VSD applications, CT's
with higher ratios are often encountered.
What this means is that if a wire were passing
through the CT and it was tapped for 200:5 and this
wire were carrying a current of 100 amps, the
current coming off the CT would be 2.5 amps.

6. If the power cable running through the CT is looped
back and run through a second time, the ratio is cut
in half. The more times the cable is passed through
the CT, the more the ratio is cut. This allows a CT
to have a wide variety of available ratios. This is
important because we want to provide a ratio which
will put the pen near the middle of the chart for
normal operation of the motor. We also want to be
able to keep the underload and overload currents
somewhere on the chart for diagnostic purposes.

7. Remember that the ammeter only operates on 0-5
amps so we must cut the actual amperage to a value
within this range.
TR 200:5 TR 200:5TR 200:5
50 AMPS 50 AMPS50 AMPS
1.25 AMPS 3.75 AMPS2.5 AMPS

8. Along with proper setting of the CT ratio, we need
to select an amp chart which reads the correct
amperage for the ratio set. All this sounds trivial
but it is surprising how many field installations are
operated with either the wrong ratio, wrong chart,
or both.
Although this will have no effect on the downhole
equipment, it robs the field engineer of some
valuable diagnostic information.

9. We will now review some amp charts and discuss
some of the possible causes for the charts shown.
This is a summary of some common problems and
is not intended to be all-inclusive. These charts
are representative of field examples and actual
charts may vary somewhat from those shown but
by studying these examples and with some field
experience, amp charts can be analyzed with a
high degree of accuracy.

10. We will assume in all cases that we are operating a
unit at full load with a motor which has a
nameplate current of 40 amps. For this 40 amp
motor, we would set the overload at 115% (46
amps) and the underload at 80% (32 amps).

11. We will assume in all cases that we are operating a
unit at full load with a motor which has a
nameplate current of 40 amps. For this 40 amp
motor, we would set the overload at 115% (46
amps) and the underload at 80% (32 amps).
Should we always use these percentages for
overload and underload?

12. Here is a typical amp chart. We
know that the downhole unit is
operating correctly and pulling
nameplate amps
(we checked it with our amprobe
at the junction box). Is there
anything wrong with this pump?
60
50
40
30
20
10
1
2
3
4
5
1
0
8
6 AM
NOON
4
5
7
9
MIDNIGHT

13. The only thing wrong is that the
CT is not properly set. If we took
this chart at face value, we would
think that the downhole unit had
failed. This is why it is so
important to set the ratio
properly.
60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
CT ratio
not set
correctly

14. We changed the CT ratio and
installed a new chart and we got
this sample. What can we see
from this?
60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT

15. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This is a "normal" amp chart.
Note the spike on startup
followed by a nice smooth and
symmetrical line at 40 amps. This
is an ideal condition.
In an actual well, the amperage
may not be exactly 40 but may be
slightly higher or lower. This is
no problem as long as the chart
remains consistent day after day.
Changes in the chart may be due
to changing well conditions or
possible system problems.
Normal
Startup
It might be a good idea
to replace the chart

16. Here is an example of what is
mostly a "normal" chart with the
exception of periodic and
seemingly random "spikes".
What will cause a chart like this?
60
50
40
30
20
10
1
2
3
4
5
1
1
1
0
8
1
1
1
0
9
8
7
6 AM
N
O
O
N
1
2
3
4
5
6 PM7
9
M
I
D
N
I
G
H
T
2

17. Trouble Shooting
60
50
40
30
20
10
1
2
3
4
5
1
1
1
0
8
1
1
1
0
9
8
7
6 AM
N
O
O
N
1
2
3
4
5
6 PM7
9
M
I
D
N
I
G
H
T
With the SPS, the amperage
varies inversely to the voltage for
a constant load. If the primary
supply voltage decreases, the
SPS current will increase to
compensate. The most common
cause for these spikes is periodic
heavy loading on the power
system as could be caused by
startup of high horsepower
equipment elsewhere on the
system. Could also be caused by
lightning strikes somewhere on
the power system.
Primary
Power
Fluctuation
"Spikes"
Spikes
2

18. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
1
0
9
7
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
Here is a chart which shows
startup followed by a gradual
decrease in amperage until about
7:30 AM where the line becomes
very ragged. At about 8:30 AM,
the amperage takes a drastic
drop and becomes very smooth.
What has happened to this unit?
Gradual decrease
Amperage
becomes
erratic
3

19. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
0
9
8
7
6 AM
NOON
3
4
5
6 PM
7
9
MIDNIGHT
When the unit is first starts, the fluid
level is high so production and current
are slightly high. As the fluid level is
reduced, the current decreases until the
level is so low that gas begins to form
at the intake. The wide variation is
specific gravity cause the erratic
amperage. Eventually enough gas
forms so that the pump "gas locks".
When the pump is gas locked, it is not
producing any fluid. Note that, even
though the pump is not producing fluid,
the motor is continuing to run
(amperage is not zero). This will cause
the motor to eventually burn since there
is no fluid movement to cool it.
Gas
Locking
Pump has
gas locked
3

20. 60
50
40
30
20
10
1
2
3
4
5
1
1
1
0
8
1
1
1
0
9
8
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
In this case, we need to raise the
underload setting so that the unit
shuts off if it gas locks. Shutting
the unit down may clear the gas
lock although if a check valve is
installed, it may prevent it from
clearing. If possible, choke back
the production to raise the annular
fluid level. It may be necessary to
lower the pump if there is room in
the well to gain additional
submergence. It might also be wise
to resize to a smaller unit.
If a VSD is being used, reduce the
frequency.
Gas
Locking
Pump has
gas locked
3

21. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This chart shows high current
after startup which eventually
drops down to a "normal"
value. If the overload were set
at 46 amps, this unit could not
continue to run. The overload
must be set higher than 60
amps (or it is not working).
What could cause a chart like
this?

22. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
1
0
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
One possible cause is that the pump is
unloading the well of heavy kill fluid.
The high gravity fluid causes an
increase in current until it is all
pumped out of the well -- then the
current drops to a normal value. If this
condition is to be expected, it may be
necessary to temporarily raise the
overload setting until the kill fluid is
gone and then set it to the normal
value. If this condition is expected to
last for more than a few minutes, it
may be necessary to use a larger
motor than normal so that the overload
does not cause high internal
temperatures which may reduce the
operational life.
Unloading
Heavy
Kill Fluid
Note: If a VSD is being used, try
lowering the hertz to reduce the
load until the kill fluid is gone.

23. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This chart shows a unit which
starts and runs for some hours
with gradually decreasing current
until it becomes very erratic. The
unit stops for 3 hours and
repeats the cycle. It restarts just
after noon and runs longer but
eventually stops.
What would cause this type of
chart?

24. 60
50
40
30
20
10
1
2
3
4
5
1
1
1
0
8
1
1
1
0
9
8
7
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This is a case where the pump is
producing more fluid than the well
can deliver. The pump is lowering
the fluid level, hence the
amperage, until free gas begins to
form at the intake. The low
gravity gas mixed with the high
gravity fluid causes wide swings
in current. The unit eventually
shuts off on U/L and automatically
restarts after three hours.
Possible solutions are to choke
back on production, lower the
pump further in the hole, or resize
to a smaller unit.
With a VSD, try lowering the
frequency.
Pump Off
with Gas
Interference

25. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This chart is similar to the
previous one except that the
amperage is fairly steady prior to
shut-down.
What will cause this?

26. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This is also a case of "pump-off"
except that there is not much gas
in the reservoir to cause
interference in the pump.
Corrective measures are the
same as before. If this
conditions develops after several
months (or years) of normal
operation, it may be that skin
damage is reducing the well
productivity. Stimulation may
restore the productivity to the
original level (or better).
Pump Off
(no Gas
Interference)

27. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This chart is similar to the pump-
off chart except that there are
some additional spikes at 7:00
AM, 1:00 PM and 7:00 PM.
What is causing this chart?

28. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
1
0
9
8
7
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
The additional spikes are due to
failed restart attempts. The
restart timer is set too low and
the pump is trying to restart
while there is insufficient fluid in
the wellbore and it trips due to
underload. Immediate action is
to increase the automatic restart
time. Long-term, the unit needs
to be resized.
Pump Off
w/ False
Restarts
Failed Restart

29. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This chart also looks very similar
to pump-off except that the
running time is of very short
duration. This is very harmful to
the SPS and should be corrected
immediately. Too many restarts
stress the motor and cause heat
buildup which is never fully
dissipated.
What will cause this type of
chart?

30. 60
50
40
30
20
10
1
2
3
4
5
8
1
0
6 AM
NOON
3
4
5
6 PM
7
9
MIDNIGHT
This chart could be caused by a pump
which is too large for reasons explained
before or, oddly enough, one which is too
small (i.e. not enough TDH). In the latter
case, the pump may be able to produce
fluid to the surface when the fluid level is
high but, as it draws down, the pump
cannot produce enough TDH to get it to the
surface -- effectively shutting the well in.
Checking the DMT reading or fluid level
will help determine if this is the case.
Closing in the discharge valve and
observing the back pressure will also
indicate which condition exists but make
certain the piping can handle the pressure
before attempting this.
Excessive
Cycling

31. This chart could also be caused by
a plugged discharge line or a
closed valve in the wellhead or
flowline.
Some low permeability wells are
produced intentionally by cycling.
If this is the case, a soft start
device should be used to reduce
stress on the motor.
If a VSD is used, try a lower
frequency. A VSD gives an
"automatic soft start" so stress on
the motor is reduced.
60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
Excessive
Cycling

32. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This chart shows a unit operating
near the correct level but the
chart is very "fuzzy".
What will cause this type of
chart?

33. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This chart is almost invariably
caused by free gas being
ingested into the pump although
it is possible that emulsion
production could also cause it. It
may be possible to smooth out
the line by choking back or
lowering the pump. Producing
free gas will usually reduce the
stock tank production rate so it is
beneficial to reduce the effect.
Many pumps are operated with
this kind of chart. As long as the
underload is set properly, there
should be no major problems.
Free Gas
in Pump

34. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This chart shows a unit which
ran for a while and then went
down on underload and never
restarted.
What would cause this type of
chart?

35. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This could be caused by
producing a low density fluid
which is not properly loading the
motor. If production tests show
that fluid is present, try lowering
the U/L setting. This should be
done with caution as setting it
too low will not protect the
motor.
Another possible cause is failure
of the U/L time-out delay in the
motor controller. A broken shaft
could also result in a chart like
this.
Under-
current
Load

36. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This chart shows a normal start-
up at 4:00 AM followed by a
gradual reduction in current
where it steadies out at about 20
amps until midnight when the
unit shuts down on overload.
What has likely happened here?

37. 60
50
40
30
20
10
1
2
3
4
5
1
1
1
0
8
1
1
1
0
9
8
7
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This is a case where the unit
pumped the well off to the point
that there was no fluid being
produced so the unit was
running at idle load until enough
heat built up to cause the motor
to burn which is when it tripped
on overload. This is a case
where the underload was set to
low. Underloads need to be
raised and unit should be
resized.
U/L
set below
"No Load"
Idle Amps
Unit trips on O/L (burns)

38. 60
50
40
30
20
10
1
2
3
4
5
1
1
1
0
8
1
1
1
0
9
8
7
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This is a chart for a unit which is
being controlled by a tank level
switch. A common application
for SPS's is to produce into a
holding tank. This tank will have
a level controller which will shut
the unit off when it is full and
allow it to restart when the level
drops to a certain point.
Is there anything wrong with this
chart?

39. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
1
0
9
8
7
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
The problem here is that the
automatic restart time is set too
short. When the pump stops, the
fluid in the tubing column will tend
to fall back down through the pump
causing it to "turbine" or backspin.
While this is not a problem in itself,
if the unit is restarted while this is
occurring, a broken shaft could
result. While a check valve may
help guard against this, they can
leak and should not be relied upon.
To give complete protection, a
backspin relay should be used in
the motor control circuit.
Otherwise, set the restart timer to a
minimum of 30 minutes.
Tank Level
Controller
Downtime too
Short

40. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
9
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This chart shows a normal
startup followed by a period of
near normal current. At 7:00 AM
the current begins to increase
until the unit finally trips on
overload and stays off. There is
no automatic restart on an
overload trip.
Normal
Amps
O/L
Trip

41. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
Until the cause of the O/L is
cleared, restart should not be
attempted.
Common causes of this problem
are:
1) increased fluid gravity,
2) sand production,
3) viscosity increases (emulsion
formation),
4) mechanical or electrical
problems downhole,
5) electrical power supply
problems, etc.
The complete installation should
be checked out thoroughly.
Overload

42. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This chart shows a normal start
followed by a period of erratic
current which smoothes out to a
normal curve.
What will cause this type of
chart?

43. 60
50
40
30
20
10
1
2
3
4
5
8
1
0
6 AM
NOON
3
4
5
6 PM
7
9
MIDNIGHT
This is often caused by debris being
pulled into the pump such as scale, sand,
muds, etc. While this is not uncommon,
it is not desirable as these materials may
adversely affect pump wear. In cases like
this, the well should always be bailed
prior to running the pump to remove the
foreign material. If this is caused by
unconsolidated sand, it may be wise to
partially choke the well on start up and
slowly increase production -- especially
on wells newly converted from rods
which produced a lower flow rate. The
reduced rate should still provide
adequate cooling for the motor however.
Pump
Handling
Solids

44. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This chart shows a normal start
followed by about 13 hours of
good current. Then followed
three hours of voltage spikes
which ended in the unit tripping
on O/L. This is followed by five
spikes between 3:00 AM and 5:00
AM.
What has happened here?

45. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This chart is not too unusual
except for the five manual restart
attempts.
An overload is caused by
something and a restart should
not be attempted until the problem
is resolved.
These restarts can destroy an
otherwise good piece of
equipment.
Excessive
Manual
Restarts

46. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This chart shows a very erratic
current until the unit finally trips
on overload. There is no
automatic restart and manual
restart should not be attempted
until the problem is resolved.

47. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
Wide variation in specific gravity,
viscosity, surface pressures or
production of debris in the pump
can cause a chart like this.
Some common results
associated with this kind of
overload are a frozen pump,
burned motor, burned cable,
blown fuses (primary and/or
secondary), etc.
Erratic
Current

48. 60
50
40
30
20
10
1
2
3
4
5
1
0
8
1
1
6 AM
NOON
1
2
3
4
5
6 PM
7
9
MIDNIGHT
This chart shows a normal
startup followed by a periodic
gradual increase in production
followed by a sudden drop to
normal current. The chart shows
this occurs over a fairly
predictable time interval.
What could cause this?

49. 60
50
40
30
20
10
1
2
3
4
5
8
1
0
6 AM
NOON
3
4
5
6 PM
7
9
MIDNIGHT
One possible cause is emulsion
formation in the pump which periodically
clears. If this is the case, an emulsion
breaker should be considered.
This can also be caused by decreasing
surface voltage due to other heavy
equipment on the line which is cycling
on and off. Try to reduce demand on the
system.
This may even be caused by a unit which
is on a generator if the regulator is faulty
causing fluctuation in voltage or speed
changes resulting in changing power
frequency. Repair the generator.
Emulsion?
Surface Load?
Generator?

50. Sometimes we are faced with trying to guess what
is wrong with a pump (or well) based on very
limited data.
The following illustrations are taken from actual
experiences and, although not comprehensive, may
be helpful in diagnosing problem wells.

51. Say we have a new unit in a well which was
designed to produce 3000 BPD. It did for a few
days but then is only making 2500 BPD. We look
at the amp charts and find that the amperage is
lower than we expect.
What could possibly be wrong with the unit?

52. The first thing to do is determine if we have an
actual performance test for the pump. Not all
pumps match the catalog curve exactly and if this
particular pump tested to the bottom tolerance on
the head-capacity curve, it may be performing
exactly as it should.
Well we called the factory for a curve and found
that it tested pretty close to the catalog curve.
What else could be wrong?

53. The fact that the pump was performing to the 3000
BPD requirement for a couple of days and then the
production dropped may lead us to suspect that
the well data were bad.
When the unit is first started, the fluid level in the
well is high due to the static reservoir pressure
elevating it.
When we run that unit, we will pump the level down
to the producing level -- but this takes time.

54. One other very useful piece of information would be
the intake pressure (or a fluid level if we are taking
sonic shots).
If the fluid level is down, we might suspect bad well
data.

55. On the other hand, if the fluid level is
up, we could have several possibilities.

Be careful, however, when interpreting
sonic levels because if the well is very
gassy, it is possible to have several
hundred feet of low density foam at the
top and the sonic log cannot tell what
the density of the fluid is -- it only
knows where it is.

56. We have determined that our fluid level is an
accurate estimate and it is still high.
One possibility is that the pump is partially
plugged internally. This will decrease the
volumetric capability of the pump and restrict the
flow. Since we are not pulling the well as hard, the
fluid level would come up.
In this case, whether the amperage goes up or
down will depend on the shape of the particular
pump's BHP curve.

57. Another possibility is that we have a tubing leak
and the pump is recirculating fluid. As far as the
pump is concerned the total TDH requirement is
reduced so the pump is producing more fluid.
Some of it makes it to the surface and the rest
recirculates back to the pump intake. We are
again pulling less on the well (the reservoir is only
giving up what we produce to the surface.
Whether amperage goes up or down again
depends on the shape of the BHP curve.

58. So a plugged pump and a tubing leak can look
very much alike. We can pressure up the tubing to
check this without pulling the unit.
It is still possible to misinterpret this as check
valves can leak.

59. By the way, it is possible to plug a pump several
places. Partial plugging in the stages themselves
may be inconvenient but not a major problem. We
may even be able to remove this with acid
depending on what type of plugging it is.
If the pump intake were to actually to plug off, the
pump would try to produce the oil out of the
protector and the motor and would most likely fail
very quickly.

60. Another possibility for low production with higher
than expected current and fluid level is viscosity.
If we are producing a viscous fluid and we did not
account for this in the design, we would have
undersized the pump for the application.

61. If everything checks out okay and our pump
meets the published curve and we still have low
production, we should look at the true rotational
speed of the pump. Catalog curves are based
on 3500 RPM (even viscosity corrections correct
from the 3500 RPM curve).
If the motor is not turning at that speed, we will
get less production.

62. What about the case where the production
decline is not so steep but diminishes gradually
over a few months or even years?
This could be a case of a "worn out" pump or
declining well productivity or both.
If the well productivity is down and the company
decides to workover the well when the pump is
pulled, it would be a good idea to review the
expected well productivity before simply
replacing the unit for another of the same size.

63. A well workover may enhance the productivity
very much and may even improve it beyond what
it was initially (for the first pump). If this
happens, a resizing of the SPS equipment may be
necessary. This could require a larger volume
pump if a higher flow rate is desired and/or fewer
stages.

64. What happens if we have looked at every
reasonable possibility and accounted for gas,
viscosity, tubing leaks, etc. and know our well
data is very close and we are still too low on flow
and head.
There are a couple of other possibilities we may
have overlooked.
What are they?

65. What if we have 540 equipment in a 7" 29 ppf
casing or 456 equipment in a 5.5" 20 ppf casing as
an example?
Depending on the horsepower of the motor, we
may have a restriction downhole that we have not
really accounted for.
Loss in feet per foot of motor length =
( I.D. - O.D. ) x ( I.D. + O.D. )
3 2
1.4 x
2
BPD
1000
BPD = Flow Rate in Barrels per Day
I.D. = Casing Inside Diameter in Inches
O.D. = Motor Outside Diameter in Inches

66. In higher flow rate -- higher horsepower
applications, even though the motor section is
relatively short in comparison to the total well
depth, we can have a very high pressure drop
across the motor.
If we do not have enough pump stages to
compensate for this, we will be short on head and
this may be very significant.

67. Another possibility is that, if the unit is running on
a generator, the gen set may not be operating as
we expect.
We have run across one example of a major oil
company in a very warm climate where most of the
pumps were run on generators. The Production
Department was responsible for sizing and
operating the pumps but the Electrical Department
handled all the generators.

68. The PD was baffled that production was off and
went through a field wide test to see if the units
were operating in reverse rotation.
Since the units were actually hooked up by the
ED, they were deeply offended by the implication
that they did it wrong and felt that REDA had
made this suggestion.

69. It turned out that ED was slowing down the
generators from 55 Hz in the Winter months to 50
Hz during the Summer without bothering to tell
anybody.
ED did not realize this would affect production and
simply wanted to protect the Gen Set.
All PD could tell was that production was way off
and they placed all the blame on faulty REDA
equipment.