Analysis of 3-D P-S seismic data: Joffre, Alberta

Glenn A. Larson and Robert R. Stewart

ABSTRACT

A 3-D P-S seismic survey acquired in the Joffre region of central Alberta has provided a cost-effective manner to acquire shear data volumes. The data discussed here were acquired by the Colorado School of Mines (Al-Bastaki et al., 1994) and processed by Pulsonic Geophysical Ltd. Three one square mile data sets are further analyzed in this paper: The conventional pure P-wave data and two anisotropic converted-wave products (the P-S1 and the P-S2). The shear data are of good quality and allow the construction of Vp/Vs and delay-time maps for both the slow and fast shear-wave polarization. The delay-time maps reveal a localized stress regime that can be mapped at depth. The Vp/Vs maps show an anomaly in the Viking interval which suggests a higher percentage of sand. There is more than one factor affecting the Vp/Vs calculations for the Nisku level, which has prevented making a direct inference of a change of lithology between dolomite and anhydrite.

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