Using AVO Crossplot and Polarization Attributes to Identify Anomalies of Gas Effect

P166 USING AVO CROSSPLOT AND POLARIZATION ATTRIBUTES TO IDENTIFY ANOMALIES OF GAS EFFECT. Abstract 1 In this paper we study the causes of amplitude anomaly observed on true amplitude stacked seismic data in southern Algerian gas field using AVO crossplot and hodograms analysis. We present an example associated with Carboniferous gas sandstones in Sbaa basin. The two factors that strongly determine the AVO behavior of sandstones reflections are the normal incidence reflection R(0) called the intercept and the relative change in amplitude with incidence angle and offset expressed by the gradient (G) that mostly depends on the contrast of Poisson’s