EP 1110-1-27
27 Jan 00
Table 2-3. Features of Water-Level Measurement Methods
Type of water-level
Advantages
Disadvantages
measurement
Requires wellhead access and unobstructed water
Electric sounder
Commonly available, reliable
surface access, probe will foul in floating material
when maintained, accurate under
on water surface, mechanical aging of conductor
most water-only conditions (+0.02
wire must be considered, cross-contamination is
in.), not highly subject to
possible, requires personnel to take levels and
downhole fouling. One sounder
manually enter data.
can be used on multiple wells.
Relatively inaccurate (+1 in. or more), subject to
Airline (gauge
Inexpensive, no need for direct
fouling, requires personnel for taking levels and
measurement) or
access to water level surface, each
manual entry of data.
instrument
well has a dedicated airline.
measurement)
Subject to fouling, requires personnel for taking
Airline (instrument
Inexpensive, no need for direct
levels.
measurement)
access to water level surface, each
well has a dedicated airline. With
instrument, improves accuracy to
electric water-level sounder range.
Data recording possible.
Relatively expensive per unit, requires regular
Water level
Relatively accurate when properly
maintenance to deter fouling. If maintenance not
transducers
selected and maintained, permits
performed, automatic systems may record
automatic data querying in
inaccurate (useless) data.
SCADA* system, dedicated to
well, no personnel exposure to
water, no direct water access
needed.
* Supervisory, control, and data acquisition. Note that all these water level monitoring methods provide data that
can be manually entered into SCADA databases. Note that all conventional water level measurement systems are
fouled by non-aqueous-phase liquids and will yield inaccurate results.
(b) Increases in amperage on start or run cycles over listed service factor amps indicate
Loose terminals in the control box or possible cable defect.
Too high or low service voltage.
Motor windings are shorted.
Mechanical resistance such as sand in bearings.
(c) A drop in typical "run" amperage indicates a loss of mechanical resistance against motor
operation. This datum, in combination with reduced flow and/or pressure data, can be used to confirm that
a problem has developed in pump output, such as if a hole has developed in the pump discharge pipe.
(d) Deviations in circuit ohms indicate wiring problems. Low values on one or more line legs
indicates a potential motor short. Greater-than-normal values indicate poor cable connections or joints, or
windings or cables may be open. If some values are higher than normal and others lower than normal,
drop leads may be mixed.
(e) Megaohm detections outside the circuit indicate ground faults. For a motor installed in a well,
if resistance between any wire lead and true ground is <0.5 MΩ, motor damage is likely to have occurred.
(f) Voltage imbalance in three-phase (3-φ) systems causes excessive motor aging and poor
performance, and should also be checked routinely.
2-12
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