Inversion approach to estimate acoustic impedance from petrophysical data in absence of density and sonic logs

• The paper is mainly addressed to introduce a novel formula to determine the acoustic impedance in the absence of density and velocity data.
• The paper introduces a new definition for the acoustic impedance from Neutron log.
• The new formula depends mainly upon the density response equation, the elastic definition of the impedance and on Raiga-clemenceau et al. (1988) equation.
• The paper contains a good and simple review on the acoustic impedance.
• Test and application of the suggested approach in two intervals from different wells in the Gulf of Suez Basin of Egypt are demonstrated.

Acoustic impedance is an important parameter for seismic and direct geologic interpretation and can be defined as the product of density and velocity, in the absence of density data or if the well suffers from a rough hole condition and/or irregularities, and also in absence of velocity or sonic data, another approach to determine such an important parameter must be used.This paper aims to introduce a new definition for the acoustic impedance by introducing a formula for estimating such a parameter from Neutron log and also contains the effect of matrix and fluid. This formula depends mainly upon the density response equation, the elastic definition of the impedance and on Raiga-clemenceau et al. (1988) equation.Test and application of the suggested approach in two intervals from different wells in the Gulf of Suez Basin of Egypt reflect how far such treatment is more or less reliable and accurate.