Determination of reflection coefficients by comparison of direct and reflected VSP events

J. E. Lira, A. B. Weglein, C. W. Bird and K. A. Innanen


VSP experiments provide a much greater opportunity to estimate local reflectivity information than do surface-constrained experiments. In this paper we describe a simple, data driven means by which the reflection coefficient associated with an interface at depth, uncontaminated by transmission losses, may be determined, regardless of the origins of these losses or of the overburden parameters associated with them. An amplitude correction operator is formed through a comparison of the direct and reflected waves just above a generating interface. A field data example from the Ross Lake heavy oil field in Saskatchewan, Canada illustrates the method. Our sense is that these results indicate applicability to more complex geometries, walkway or 3-D VSP surveys, assisting with the construction of AVO/AVA panels.

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