AKUSTISK LOGGINGSINSTRUMENT.

摘要

A plurality of transducers (40) are carried by a logging sonde (10) for transmitting and receiving acoustic pulse signals. The transducers are operated as a plurality of arrays, each array including four transducers disposed along an arc extending circumferentially of the sonde, two transducers being operated as transmitters (T) and two as receivers (R). The transducers are arranged, for example in helices, so that the arcs complete a circumference about the sonde. The amplitudes of the received acoustic pulse signals are measured, the travel time of an acoustic pulse signal travelling between the two receiving transducers is determined, and the attenuation of the acoustic pulse signal travelling between the two receiving transducers is thereby determined. When the sonde is logging a cased borehole, the attenuation signal for each sector is representative of the quality of the cement bond between the casing and the borehole in that respective sector. This permits the azimuthal location of channels or fissures between the casing and the cement.