Which log helps to verify how well casing has been cemented to the formation?

The acoustic log is a crucial tool for verifying the integrity of a casing and its cement bond to the surrounding formation. This type of log measures the travel time of sound waves through the casing and the cement, which can indicate how effectively the cement has bonded with both the casing and the formation.

When the cement has been properly placed and has created a good bond, sound waves travel efficiently through the cement, reflecting the quality of the cement-job. Any anomalies or discrepancies in the travel times of these sound waves can suggest potential problems, such as voids or inadequate cement coverage, which could compromise the casing's structural integrity and overall well integrity.

While other logs serve important functions, they do not directly measure cement bond quality in the same way. For instance, the caliper log checks the diameter of the borehole, providing information on the physical condition of the wellbore, but it doesn’t assess cement quality. The temperature log helps monitor well conditions by measuring temperature at various depths, while the gamma log is primarily used to identify lithology and the presence of natural radioactivity in formations.