The gamma-density log across the cemented interval can reveal the areas where cement does not fill the gap between casing and formation.
This method can not qualify if cement develops a bond with casing and formation.
Gamma Density Cement Logging is usually used in tandem with Temperature 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
[ Temperature Cement Logging ][ Acoustic Cement Bond Logging ]