Temperature Logging - Cased-Hole Log Analysis and Reservoir Performance Monitoring - page 108

Fig. 8.5 Cement-top pick
from temperature log
Lost-Circulation Zones
In the event that circulation is lost in a currently drilling well, a temperature log can
be a useful indicator of the thief zone in question. Just below the point of lost circu-
lation, the mud in the hole is likely to have been stagnant for some time and there-
fore to have assumed a higher temperature than the mud in the column, which is still
free to circulate. Thus, a temperature discontinuity will exist across the lost-
circulation zone. Figure 8.6 illustrates the effect.