Extract AVA attributes and evaluate their variability

After amplitude balancing, we perform split-step phase shift migration and extract multiple angle gathers from the image using multiple equal-probable velocity models. Then we follow Gratwick's algorithm () to get intercept and gradient. After extracting intercept A and gradient B from angle gathers, we first cross-plot A and B (, ) and muted those clusting points in the plots which correspond to background values. Then we transformed the muted plots back to two panels A and B. A negative A*B value often is a hydrocarbon indicator. The variability of AVA attributes can be assessed by comparing and contrasting their multiple realizations. A convenient way to analysis the variability is to use histogram. Because the count used here is the function of CMPX, depth and magnitude of AVA attributes, the histogram used here is a 3-D cube.