The impact of attenuation on the resolution of multicomponent seismic data

Richard A. Bale and Robert R. Stewart

ABSTRACT

In this paper, we undertake a comparative analysis of the expected effect of constant Q absorption on different modes, illustrating these effects by modelling absorption for homogeneous and layered models. We find that when S- and P-wave attenuation filters are compared in depth, they are exactly equal for the same Q value, in the homogeneous case. Higher wavenumbers for given frequencies in the source wavelet give an initial advantage to S-wave resolution in depth, which may be lost to attenuation if S-wave Q is less than P-wave Q, and/or if there are very low shear velocities in the near surface. Finally, dispersion, which inevitably accompanies attenuation, will differ for P and S modes with different Q values, resulting in event correlation errors. One, perhaps surprising, implication of this work is the need for better low-frequency recording to enhance shear-wave resolution. Additionally we provide relationships between interval and effective parameters including a Dix type inversion formula which could be used to derive shear-wave Q values from converted wave data.

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