DETERMINATION OF REFLECTION COEFFICIENTS BY COMPARISON OF DIRECT AND REFLECTED VSP EVENTS

作者：Lira J E^*; Weglein A B; Bird C W; Innanen K A

来源：Journal of Seismic Exploration, 2012, 21(4): 361-376.

• VSP
• absorption
• amplitudes
• frequency domain
• reflection coefficients
• borehole geophysics

Lira, J.E., Weglein, A.B., Bird, C.W. and Innanen, K.A., 2012. Determination of reflection coefficients by comparison of direct and reflected VSP events. Journal of Seismic Exploration, 21: 361-376. 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. Error grows as the distance above the generating interface at which the two events are compared grows. The formulation of the problem is in the plane-wave domain, but with a slight additional error the approach can be applied to data associated with fixed zero or nonzero offset. The method can be applied to generate scalar reflectivity values in acoustic/elastic environments, or phase and amplitude spectra of reflectivities in anacoustic/attenuative environments. 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 3D VSP surveys, assisting with the construction of AVO/AVA panels.

• 出版日期2012-12