Predication of Shear Velocity at Shaly Sand Reservoir Rock

The magnitude of shear velocity (Vs) in geomechanical rocks properties leads many of petrophysics and geophysics to use and investigate simple and accurate technique for it, especially when this parameter is not measured by sonic tools. If there are no core samples available for calibration, empirical relations could be used, that based on measurable physical properties. The results emphasize the importance of local calibration before one utilizes any of the empirical relationships presented. During this study several trials, were carried out aimed to predicate shear velocity in shaly sand reservoir of late Jurassic to Late Cretaceous at southeast of Sirt Basin, Libya, by using gamma ray, compressional travel time and density logs. Therefore, a new approach by modified derived Poisson’s Ratio Equation for shaly sand is introduced as an important part
of shear velocity determination. This modified equation design upon deeper, highly compacted and cemented sandstone has a Poisson’s ratio values range between (0.18 – 0.20), which is fairly similar to the studied
reservoir condition.