HO, S. M., S. S. LEE, and G. W. PURNELL, Texaco, Inc.

ABSTRACT: Comparison of P-Wave AVO Techniques for Locating Zones of Fractured Dolomite within Nonreservoir Limestone

Earlier work by Pardus et al. (1990) showed that V<p>/V<s> (t<s>/t<p>) ratios, interpreted from p-wave and s-wave CMP stacks, could be used to identify dolomitized portions of the carbonate Trenton formation at Scipio field in Michigan. (The dolomitized zones can be associated with commercial accumulations of oil.) However, the t<s>/t<p> technique requires that special field effort be made to record P-wave data and S-wave data. We demonstrate that it is possible to achieve the same goal by using AVO analysis of P-wave data alone to detect the lateral changes. This involves detecting subtle AVO changes using somewhat noisy seismic data. In seeking a robust way to isolate the anomalies, we compare three techniques for P-wave AVO analysis: (1) automati analysis of each peak and trough using Shuey's (1985) approximation; (2) interactive analysis of the relative AVO of target and reference events (Chiburis, 1987); and (3) interactive analysis of picked events followed by inversion for V<s> (Chou et al., 1990). For our data, the Chiburis relative-AVO technique appears to be the most robust and provides results which agree with well control, without requiring a priori information.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.