The present study reveals the application and value of Amplitude versus Angle (AVA) modeling and attribute analysis for preparing a de-risking model hydrocarbon prospects. Public domain seismic and well data from the Australian offshore was used and AVA modeling applied together with attribute analyses to study the patterns in the rock properties for de-risking hydrocarbon prospects.
In quantitative applications of seismic data, AVA modelling and attribute analysis are widely used for lithology and fluid analysis. AVA analysis has wide applications in the exploration domain including AVO class identification and discrimination of hydrocarbons in the sediments. As AVA attributes are directly related to elastic-property contrasts associated with rock and fluid properties this approach can be used as an alternative to more sophisticated methods like seismic inversion.
In order to perform the AVA modeling and attribute analysis a series of forward models in association with rock physics models integrated together. Aki-Richards method that relates AVA attributes to contrasts in the three elastic parameters P-wave impedance (Ip), S-wave impedance (Is) and density (RHOB) is used to generate synthetics and the amplitude responses have been measured for different fluid substituted scenarios. For quantitative applications the AVA attributes, AVA intercept and gradient (A & B) were cross plotted and the patterns in rock property studied. The results reveal that synthetic seismic responses together with the AVA analysis show changes for different porosity scenarios and a prospect based trend of decreasing or increasing can be established.
AVA modelling and attribute analysis ultimately leads to a better lateral prediction and discrimination of hydrocarbons. It may be concluded that assessing the effect of fluid-substituted logs for different lithologies and associated AVA seismic response improve the prediction in reservoir characterization.
