Estimating Sand–Shale Formation Pore Pressure

Abstract

This article presents a comprehensive evaluation method of estimating sand–shale formation pore pressure by using sonic velocity and other logging data. The method takes the influence of porosity, density, shale content, effective stress, and some other physical properties of sand–shale formation on sonic velocity into account. The influence and related logging data are combined to estimate the effective stress, and then pore pressure can be obtained by the effective stress principle. Using this method, software was developed and it applied in the well site. Its applications indicate that this method can accurately estimate the abnormal pressure of a sand–shale formation.