Towards field evidence for anelastic and dispersive AVF reflections

Chris Bird and Kris Innanen

ABSTRACT

Strongly anelastic seismic targets are expected to exhibit amplitude-vs.-frequency (AVF) variations. Some field and laboratory evidence of this type of behaviour exists, but much more evidence is needed before definitive statements are made about the benefit of AVF to monitoring and/or exploration. The Ross Lake heavy oil field has been subject to several VSP experiments through geological structures with strong variations in Q; one of the reflectors, at the top of the Mannville group, is a reasonable AVF candidate. By combining a time-frequency decomposition tool with a methodology for extracting raw reflection coefficients from VSP data, we show that the Mannville reflection coefficient is consistent with an AVF-rich anelastic reflector. However, our control event exhibits frequency variations on comparable scales, and so at present the identification of AVF variations is not definitive.

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