AVO Analysis on Ghar Sandstone Reservoir in Hendijan Oil field

Nowadays, quantitative methods for seismic data interpretation are mostly used instead of qualitative evaluations for the description of reservoir from exploration to production phase and, over time, it will be more important in upstream oil industry.One of the most prosperous methods is AVO analysis that considers the variation of reflection coefficients versus offset between the source and the receiver. This method uses prestack data to identify hydrocarbon in reservoir and can be used as a direct hydrocarbon indicator in clastic rocks. In this paper, AVO analysis method has been described to detect hydrocarbon reservoir and AVO analysis was applied to the Ghar sandstone reservoir in Hendijan oil field. This study is carried out using 3D prestack data and well logging data. At first, forward modeling has been performed using well logging data from wells. Class 1 AVO anomaly has been recognized for this reservoir. After the forward modeling step, fluid replacement modeling (FRM) in reservoir zone has been applied and the best attributes, which had a great sensitivity to fluid, were distinguished. But FRM shows that the attributes are not sensitive to changes in fluid type. AVO anomaly on upper boundary of Ghar sandstone is affected by changes in lithology. Also, intercept-gradient cross-plot was produced by attributes. Reservoir area and zones has been discriminated with intercept-gradient cross-plots. For seismic data, various AVO attributes and cross-plots have been extracted by different methods and have delineated. Unfortunately, attributes and cross-plots were not able to detect fluids boundaries and fluid boundaries, because of the poor quality of seismic data. The results not only help to select new drilling locations more accurately, but the reservoir parameters can also be modeled with less uncertainty.