Inversion of the seismic AVF/AVA signatures of highly attenuative targets

Abstract

Frequency-dependent seismic field data anomalies, appearing in association with low-[Formula: see text] targets, have, on occasion, been attributed to the presence of a strong absorptive reflection coefficient. This “absorptive reflectivity” represents a potent, and largely untapped, source of information for determining subsurface target properties. It would most likely be encountered where a predominantly elastic/nonattenuating overburden suddenly is interrupted by a highly attenuative target. Series expansions of absorptive reflection coefficients about small parameter contrasts and incidence angles can expose these anomalies to analysis, either frequency-by-frequency (amplitude variation with frequency [AVF]) or angle-by-angle (amplitude variation with angle of incidence [AVA]). Within this framework, variations in P-wave velocity and [Formula: see text] can be estimated separately through a range of direct formulas, both linear and with nonlinear corrections. The latter come to the fore when a contrast from an incidence medium [Formula: see text] (i.e., acoustic/elastic) to a target medium [Formula: see text] is encountered, in which case the linearized estimate can be in error by as much as 50%. Algorithmically, it is a differencing of the reflection coefficient across frequencies that separates [Formula: see text] variations from variations in other parameters. This holds for both two-parameter (P-wave velocity and [Formula: see text]) problems and five-parameter anelastic problems, and would appear to be a general feature of direct absorptive inversion.

Interpretation of phase reversals in seismic reflections from attenuating targets

“…The impact of such effects on seismic reflection data has also been theoretically studied (Chapman et al, 2006;Innanen, 2011). Attention has focussed primarily on how the amplitude of the reflection coefficient varies with frequency, and an extended version of the Rutherford and Williams (1989) classification system has been developed for cases where the reflecting layer exhibits strong dispersion.…”

The influence of the Goos–Hänchen effect on seismic data processing and AVO in attenuating media

“…Seismic waves attenuate and disperse as they travel in the subsurface (Aki and Richards, 2002;Futterman, 1962;Innanen, 2011). The seismic response is recorded in the amplitude and traveltime within a finite frequency band.…”

High order approximation for scattering matrix in layered elastic medium and its application in pre-stack seismic inversion

“…This form of M and N was derived from Achenbach (1973), which was analyzed by some scholars in particular (Levin, 1986;Keys, 1989;Innanen, 2011). By Kramer's rule, Ewing et al, (1957) derived the exact expression of scattering matrix.…”