77 QUAL I TÉ GÉOPHYSIQUEAPPLIQUÉE 3 Acoustic logging 5 J.-L. Mari, C. Vergniault, F. Coppens 3.1 Introduction For many years, the transmission of an acoustic wave through media has been used for borehole measurements. Acoustic logging is an approach to measure the sound propagation velocity in geological formations, using a device composed of a transmitter and a receiver system. Originally, this measurement method, called sonic logging, was essentially intended to measure the interval (Δt) of arrival times of the first compression wave, with two receivers that are 25 to 50 cm apart, the energy being emitted by a transmitter located about 1 m from the first receiver. A slowness (inverse of velocity) curve is obtained from which is calculated the propagation velocity of the refracted sonic wave (15 to 30 kHz) in the formations. In this case, only the picking of the first arrival of the compression wave (P) in the media traversed is taken into account. The use of so-called sonic logging to determine the This chapter of Well seismic surveying and acoustic logging is published under Open Source Creative Commons License CC-BY-NC-ND allowing non-commercial use, distribution, reproduction of the text, via any medium, provided the source is cited. © EDP Sciences, 2018 DOI: 10.1051/978-2-7598-2263-8.c005
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