ABEM Terrameter SAS 1000 / SAS 4000
- 50 -
7.3
TEMPERATURE & SP LOGGING
Normally temperature and SP are logged at the first run
downwards the well, in the unstirred water and with no
polarization effects residing from resistivity measurements.
The temperature is measured to an accuracy of
1
C within the
0
C ... +20
C range and
0.1
C within the +20
C ... +50
C
range, thus permitting local temperature gradients to be studied
in detail.
When assuming high precision for temperature gradient studies,
ample time must be allowed to permit the probe to reach thermal
equilibrium vis-à-vis the fluid. Move the probe slightly up and
down a few times while waiting for equilibrium to be
established. Temperature logging should be the first log at each
station, since undisturbed water is required.
To reduce electrode polarization, attributable to previous
resistivity measurement or long storage in air, the electrodes
should be depolarised before SP logging starts.
Proceed as follows:
•
Connect all cables and electrodes as explained above.
•
Perform the Electrode Check.
•
Select the Level Check. Lower the logging probe into the
well, use the level mode to determine the depth to the water
table. Return to the Info Text menu (para. 8.2.2, point 11) and
enter the water table depth in the comments field.
•
Lower the probe to the desired depth (i.e. as indicated in the
measuring menu, 0 m for the first sample).
•
Select the Depolarise and wait for this function to finish.
•
Select Down.
•
Press
and temperature and SP will be measured, the values
stored and shown in the upper half of the LCD. An imperative
to proceed to next depth appears in the lower half of the LCD.
•
Lower the probe to next depth as indicated on the LCD and
press
.
•
Continue till the desired depth is reached and to where the
resistivity upwards logging should commence.
The voltage that is displayed will be the potential between the remote potential reference
electrode and the upper electrode, the shoulder, on the logging probe.
5.6 m
1.2 m
0.4 m
0 m
-0.4 m and
chamber e.
Logging probe with
current takeouts
