Sonic Log Analysis With The Continuous Wavelet Transform

We use the Continuous Wavelet Transform (CWT) to identify lithologic units, notably in terms of discontinuity, based on the analysis of stochastic fluctuations of sonic logs. The use of the CWT seems to be a particularly well adapted tool to extract systematically and reliably the information related to the singular part of the signal. The method has been tested on synthetic models and actual data set obtained from sonic logs in oil exploration. Starting from synthetic fractal models, we show the influence of the various statistical parameters, in particular the number of Hurst which indicates the local regularity of the medium. Its application to real sonic logs confirms the previous results. Indeed, the exponent parameter can be used to identify the transitions of the lithologic units observed in the well. This important result allows to precisely locate the areas of lithologic discontinuity related to lithological variations.