SPWLA Glossary

In acoustic transit time or sonic logging. When the amplitude of the first arrival form (cycle of the acoustic wave train is large enough to be detected by the near receiver of a receiver pair) but not large enough to be detected by the far receiver, then one or more cycles will be skipped until a later cycle arrives which has energy above the detection level. This situation is called “cycle skipping.” Its onset is characterized by a sharp deflection on the transit time curve corresponding to one or more added cycles of time between receivers. “Short cycle skipping,” where the near receiver is triggered a cycle too late can also occur, resulting in an abnormally short travel time.