-

Scope of this paper is the application of Krief’s method to petrophysical interpretation of an oil/gas reservoir in southwest of Iran. The base of this method is via shear and compressional waves. Recent development in oil industry and full-waveform sonic tools have renewed interest in the interpretation of the velocities of compressional and shear waves and their relationship to the lithology and the petrophysical parameters of formation. As we know, original researches, such as the Wyllie and the Raymer equations, are currently used in a petrophysical interpretation of formations. But these equations deal only with the compressional wave. In this paper the Krief’s method would be reviewed and applied to an oil/gas research in southwest of Iran. This method is based on a relationship between the squares of the velocities of the compressional and shear waves and porosity of a formation, which is derived half theoretically and half empirically. A cross plot of the squares of the velocities of the compressional and shear waves shows the quasi-linear relationship between the squares of the velocities.