Temperature Logging - Cased-Hole Log Analysis and Reservoir Performance Monitoring - page 116

Radial Differential-Temperature Tool
The radial differential-temperature tool (RDT) was designed to detect channels
behind pipe. The operating principle relies on the probability that the temperature in
the channel is different from the temperature in the surrounding formation. If fluid
is channeling from above or below it is probable that such a temperature difference
will be present. Figure 8.14 shows a plan view of a channel. The temperature on the
side of the casing near the channel, T w1 , is likely to be different from the temperature
of the casing opposite the channel, T w2 . Thus, a temperature sensor held stationary
at a given depth, but free to rotate through 360°, should observe a temperature fluc-
tuation if a channel with fluid flowing in it is present.
Fig. 8.14 Temperatures in and around a cased well. Reprinted with permission of the SPE-AIME
from Cooke (1979)