Far offset P‐to‐S “elastic impedance” for lithology and partial gas saturation (fizz water) identification: Applications with well logs

Abstract

In this paper, we present a formulation of P-to-S "elastic impedance" (PSEI), assuming the validity of convolutional model for PS converted waves and weak contrast between layers. We show how, for a particular analytically defined angle, PSEI can theoretically give a direct density estimator. Two applications with real well logs are shown: PSEI as best lithology differentiator in an Orinoco Belt example (also applicable to reservoirs with small acoustic impedance contrast between sands and shales), and PSEI to discriminate between commercial gas saturations and fizz water.