1. n. [Production Logging]

The frequency with which a local probe detects a change from one type of fluid to another. For example, if water is the continuous phase, the probe will respond digitally each time a bubble of oil or gas passes it. The average frequency of change is the bubble count rate, or bubble count. In this example, an increasing bubble count means an increasing oil or gas velocity. Bubble velocity can be calculated from bubble count and bubble size, the latter being estimated from an empirical correlation with water holdup. The depth at which the first bubbles are counted is a sensitive indicator of the lowest hydrocarbon entry. Since the bubble count is based on local probe measurements, both bubble count and bubble velocity can be presented as images, similar to the holdup image.

See: electric probe,  local holdup,  optical probe,  production log,  velocity image