New AVO expression and classification using pseudo-poisson reflectivity

A new expression for Amplitude Variation with Offset (AVO) is proposed. The expression introduces amplitudes as a function of two AVO attributes, the gradient and scaled Poisson reflectivity (PR). The PR is proven to be more sensitive to hydrocarbon presence than any other ordinary AVO attributes. Another advantage of the PR is that it responds to all gas and light oil-saturated sands, unlike common AVO attributes. From the new expression, a new AVO classification with two classes is introduced; the first class is Class H which represents rocks with high probability of hydrocarbon presence; the other class involves rocks with high probability of no hydrocarbon presence, named Class N. The approximation has been applied on field data from Alberta, Canada and has demonstrated a good identification of a gas-saturated reservoir. The new AVO expression and classification aim to complement other existing classifications and reduce uncertainty from their interpretations.