New AVO expression and attribute based on scaled Poisson reflectivity

A new expression for Amplitude Variation with Offset (AVO) is proposed. The expression introduces reflection amplitudes as a function of two very common AVO parameters, the Gradient (G) and scaled Poisson reflectivity (SPR). The SPR is proven to be an excellent indicator of hydrocarbon with more sensitivity to fluid than other ordinary AVO attributes. Another advantage of the SPR is that it works for all types of gas-saturated sands commonly targeted by AVO. From the new expression, a new AVO classification based on SPR is introduced. The classification involves two classes: 1) Class H, with negative SPR and negative G, represents rocks with high probability of hydrocarbon presence, and 2) Class N, with nearly zero or positive G and SPR, includes rocks with high probability of no-hydrocarbon presence. An AVO attribute combining SPR and Gradient is derived from the expression and is proposed as a good indicator of fluid presence. The approximation and the attribute are applied on Marmousi-2 model datasets and on a field data from Alberta, Canada. The attribute has demonstrated a good identification of the hydrocarbon-saturated reservoirs in theoretical model and the real field data. The new AVO approximation, classification and attribute are intended to complement other existing approximations and reduce uncertainty from their interpretations.