Bahareh Heidari - MS.C student, Institute of Geophysics, University of Tehran, Iran
Haleh Karbalaiali - PhD student, Petroleum Engineering Department, Amir Kabir University of Technology, Tehran, Iran
Mohammad Ali Riahi - Associate Professor, Department of institue of Geophysics, University of Tehran, Iran

Extended Elastic Impedance (EEI) inversion is a seismic inversion method developed for delineating fluid and lithology. EEI can estimate different elastic parameters, such as Shear Impedance,ratio, Bulk modulus, Lame parameters and Poisson's ratio. The most significant ability of EEI method is that it can directly relate impedance attribute to petrophysical parameters such as porosity, water saturation and clay volume which are critical for determining reservoir zone. Every single parameter can be evaluated by extending incident angle beyond that of in Aki and Richards’s equation and giving different weight to intercept and gradient values. This method is particularly useful in areas where the sandstone reservoir has similar impedance with surrounding shale.

Extended Elastic Impedance (EEI), Petrophysical evaluation, Reservoir delineation