Volume 10 Number 4
  • E-ISSN: 1365-2478



Among the different factors that affect the amplitude of the acoustic signals measured by continous velocity logs (“V logs”) in bore holes, the coefficient of attenuation appears to be of considerable interest in the determination of some of the mechanical qualities of the formations. In particular, the attenuation seems to relate to the continuity of the matrix, thus, to a certain extent, to the permeability.

In order to eliminate the secondary factors affecting the amplitudes (such as variations of the velocity) we have found it necessary to measure the ratio of the amplitudes logged at the first and second receiver of the C.V.L. The “continous attenuation logger” developed by the C.E.P. allows us to make a continous measurement not only of the amplitudes of the first arrivals at the two receivers, but also directly of the ratio of these amplitudes.

We present here the first results obtained by the continous attenuation log (C.A.L.) in different types of formations. Comparisons are made with Velocity, Electric and Radioactivity logs.

The Continous Attenuation Log correlates well with the lithology and, in particular, gives a very good localisation of fractured and permeable zones. Although we have, as yet, but little experience with this new type of log, it seems that the first results obtained are quite promising.


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  • Article Type: Research Article
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