Abstract

Several AVO cross plot methods were compared using well data from 5 exploration drilled in deep water block in Krishna-Godavari basin. This study shows that AVO Impedance vs. Acoustic Impedance cross plot provides the best separation between gas bearing sands, water bearing sands and shale/clay. AVO Impedance (AVOI) attribute derived by normalizing the Acoustic Impedance (AI) and Elastic Impedance (EI) against the brine sand trend enhanced the facies discrimination. The predictive power of this AVOI attribute is comparable to other attributes like LMR (Lambda Mu Rho), AI, and EI. The AVOI vs. AI cross plot shows the minimal overlap of various facies with respect to each other. Ability to define the zone of confusion, zone of confidence for the study area on the basis of AVOI cross plot may reduce the risks in exploration. Also the striking relevance of reservoir porosity to facies separation may guide in assessing the quality of the reservoir. The effectiveness of this method has to be tested on seismic data.