The temperature of the cement during the cement pumping is different from the background rock temperature.
By checking the temperature difference one can assess how high the cement has gone up behind the casing.
This is the cheapest method to check the target interval was cemented, but it can not qualify if cement is filling the gap and develops a bond with casing and formation.
Temperature Cement Logging is usually used in tandem with Gamma Density Cement Logging.
The Temperature Cement Logging + Gamma Density Cement Logging tandem is mostly considered as the "old school" and being replaced widely by the more informative methods of Acoustic Cement Bond Logging.
Despite this perception many engineers find Temperature Cement Logging + Gamma Density Cement Logging being useful in analysis and complementary to the Acoustic Cement Bond Logging.
See Also
Petroleum Industry / Upstream / Data Acquisition / Well & Reservoir Surveillance / Well logging / Cased-Hole Logging / Well Integrity Logging / Cement Sheath Logging
[ Gamma Density Cement Logging ][ Acoustic Cement Bond Logging ]