Numerous approaches have been published which derive fluid indicators (often called direct hydrocarbon indicators, or DHI) from AVO equations. The main idea behind these methods is to use the linearized Zoeppritz equations to extract petrophysical parameters such as P-impedance, S-impedance, bulk modulus, shear modulus, Laméparameters, Poisson's ratio, etc. and, from cross-plots of these parameters, infer the fluid content. Often, these indicators provide a good tool to quickly identify hydrocarbon zones. But the question of whether there is a best approach and, if so, which one it is, is still under debate. The purpose of this study is to examine which indicator can most easily discriminate a gas/oil sand from its background geology, and which indicator is most sensitive to pore-fluid content estimation.
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