Angle of incidence estimation for converted-waves

Carlos E. Nieto and Robert R. Stewart

ABSTRACT

Amplitude-versus-angle (AVA) analysis represents a link between the geological properties of rock interfaces and their seismic signature with offset. This and other methods that combine seismic amplitudes with geological properties require the knowledge of the angles of incidence of the rays on the interface where the properties are being analyzed.

The objective of this work is to consider the advantages of using the three-term PS series instead of manipulating the two-term PP series (proposed by Todorov and Stewart, 1998) in the calculation of angles of incidence. A velocity model from Blackfoot area was used to indicate that the two-term series is a good approximation to the exact angles of incidence obtained by ray tracing, although it always overestimates the result. We find that the three-term series is a better approximation exact error for various cases.

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