1. n. [Formation Evaluation]

In the context of borehole logging, measurements of acoustic signals that are in the hundreds of kilohertz to the low-megahertz range. Such ultrasonic instruments are mostly of the pulse-echo type, and are used in the borehole televiewer, and in various cased-hole devices to determine corrosion and cement-bond quality.

See related terms: acoustic transducer,  sonic measurement