Equivalent reflection coefficient and AVO characteristics of the thin bed

Abstract

The reflection coefficient of thin layer varies with frequency, angle and thickness of thin bed, which is different from that of a single interface, so it is difficult to study the fine reflection coefficient of thin layer by using the Zeoppritz equation. In this study, the exact thin-layer PP wave reflection coefficient consisting of reflection and transmission coefficients of top and bottom interface is derived with the reflectivity method. Two equivalent reflection coefficients are obtained when the multiple reflection term and the higher order reflection term are ignored respectively, and their accuracy is verified by numerical calculation of different thicknesses in the weak impedance comparison model. The error between the exact value and the approximate value may be caused by the PP and PS reflection coefficients of the bottom interface. Our method shows a great relationship between the exact reflection coefficient and the equivalent reflection coefficient ignoring higher order terms or interlayer multiple reflection terms. Note: This paper was accepted into the Technical Program but was not presented at IMAGE 2022 in Houston, Texas.