A record of the difference in temperature between the opposite sides of the internal wall of a casing. The log is mainly used to detect a channel in the cement, since the fluid moving in the channel is likely to be cooler or warmer than its surroundings. The two temperature probes are held on arms that are extended to touch the casing wall at depths where a channel is suspected. The assembly is then rotated through 360o to give the radial differential-temperature log. A sinusoid indicates a channel. Temperature differences are small, typically 0.005 to 0.05oF [0.003 to 0.03oC], but can be enhanced by injecting cooler fluids from surface.

Related Terms:

differential-temperature log
production log
temperature log