Cement Bond Logging - Cased-Hole Log Analysis and Reservoir Performance Monitoring - page 200

Cycle Skipping

If a further drop in amplitude causes the peak of E 1 to fall below the preselected bias
level, detection will take place on E 3 and t will increase signifi cantly. This is

known as cycle skipping, as shown in Fig. 12.14 . Cycle skipping may be unavoid-
able in very good bonding and although it gives a hashy appearance to the

∆

t curve,
it is not all bad; at least there is a good bond! Figure 12.15 gives an example of cycle
skipping in a very well-bonded section.

∆

Fig. 12.13 ∆ t stretching due to good cement bond. Courtesy Schlumberger

Fig. 12.14 Cycle skipping. Courtesy Schlumberger