1. n. [Formation Evaluation]
An induction tool or log that consists of several mutually balanced arrays whose signals are recorded separately and combined in software to produce the response desired. Typically, there is one transmitter and five to ten pairs of receivers and bucking coils that are balanced to remove direct coupling. The signals are combined in a wide variety of ways to produce the responses desired, as for example, deep-reading, high vertical resolution or some combination of both. There are trade-offs in any response. For example, a deep-reading log typically will not have high vertical resolution. If it does, it will be more sensitive to the invasion condition and cave effect.