Seismic Data Conditioning of Partial Stacks for AVO – Using Well Offset Amplitude Balancing

Abstract

AVO analysis is increasingly becoming part of the everyday workflow, however it is often found that existing data sets require further conditioning in order to extract accurate reservoir properties within the zones of interest. We present a systematic workflow which incorporates the understanding taken from the well based AVO analysis to align the seismic data to the true AVO signal of the earth. Compensation for NMO stretch and amplitude are key to this. The well based AVO Seismic Data Conditioning approach adopted here corrects for the relative amplitude loss between near and far offsets, often referred to as offset balancing. Each step progressively improved the final results of creating an Intercept and Gradient reflectivity, additionally the final partial stacks honour the AVO of the log based synthetics. The wells and the seismic now share the same dynamic range of AVO characteristics as those seen at the wells. Whereas previously we had a noisy gradient reflectivity at the top of the reservoir the improved data now showed characteristics which were more indicative of geological features. Seismic Data conditioning of the partial stacks is considered a cost effective alternative to seismic data conditioning of the prestack gathers.