AVO Processing Calibration

Over the years AVO technology has been deployed in both efficient and inefficient ways in different sedimentary environments, normally functioning as a lithology indicator and sometimes as a direct hydrocarbon indicator. Several factors may be regarded as resposible for the unsuccessful applications. However, the most basic one, the properness of the processing sequence to the problem at hand, is sometimes underestimated. The ambiguity of the AVO technique and the presence of coherent noise in the data are other major factors. In this study, I developed a method to check the consistency of the AVO measurements produced by different processing sequences on a noise contaminated data. An extense reprocessing work has been employed in a marine seismic dataset, where an amplitude anomaly is related to the presence of high porosity sands saturated by light hydrocarbons. The sandstone reservoir is encased in marine shales. The anomaly is localized and is characterized by a decrease in density and Poison's ratio in the reservoir zone. The AVO signature is modeled and the corresponding normalized reflection coefficient curve is used to check the amplitude responses produced by different processing sequences. As a result of such calibration procedure the best processing sequence can be selected and it can be used for all seismic lines in the same area.