Well and Field Monitoring - Cased-Hole Log Analysis and Reservoir Performance Monitoring - page 253

Thermocouple vs. DTS Measurements
An older technology used wired thermocouples placed at strategic points along a
wellbore in order to monitor temperature changes with time or as a result of produc-
tion, injection, or other stimulation or treatment. While such measurements are
accurate and are fairly inexpensive to install the results can sometimes be mislead-
ing, as illustrated in Fig. 14.16 . In a SAGD well both DTS and thermocouple (TC)
temperature measurements are available. There are three TC measurements avail-
able along the horizontal portion of the well marked on the figure with red dots.
Taken on their own they suggest a temperature gradient as shown by the straight red
line. However a DTS continuous temperature profile paints a different picture as
shown by the continuous blue line. The black line shows the wellbore path (chang-
ing from vertical to horizontal going from left to right).
Fig. 14.16 DTS vs. TC temperature distribution in a SAGD well. Courtesy SPE 117206
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