Acoustic impedance inversion approach from petrophysical data

Acoustic impedance; is a key parameter for seismic and direct geologic interpretation and for detecting lateral lithologic variation; can be defined as the product of density and velocity, in the absence of density data or if the well suffers from rough hole condition and/or irregularities, another approach to determine such important parameter must be used.This paper aims to introduce an empirical relationship for estimating Z (acoustic impedance) using sonic, neutron, gamma ray data and shale, fluid and matrix densities, which is usually available in most wells. This formula depends mainly upon the density response equation and the elastic definition of the impedance.Test and application of the suggested approach in two different wells located in the Gulf of Suez basin in Egypt and in Williston Basin, USA indicates the reliability of proposed formula to calculate such parameters with very high degree of accuracy.