Abstract

AVO analysis is based on the anomalous increase in signal amplitude with increasing offset from reflector which contains gas. This anomaly looks strange, but it is correct for a receiver located at the subsurface reflector point and seen by plotting the reflection coefficient to the angle of incident.

For estimation of reservoir boundary the AVO anomalies should be determined for all selected CDP points of the seismic lines across the reservoir. The reservoir boundary is estimated and mapped by change of amplitude between CDP with AVO anomaly and CDP without AVO anomaly.

This process is applied to the gas sand reservoir of Baong Formation in the Alpha Structure, North Sumatra Basin. The result shows a mappable of reservoir boundary in this gas field.

Conclusion from this study is that the lateral disappearance of AVO anomaly in gas reservoir could be used as an indication for reservoir boundary.