Abstract: Interpretive Methods of Stratigraphic Modeling

Thomas R. Wittick, Alan P. Frick

A technique of utmost importance in stratigraphic interpretation measures sonic velocities and densities and their lateral variations. These variations can be indicative of changes in lithology, enabling the geologist and geophysicist to correlate, delineate, and quantify significant stratigraphic units and perform facies analysis where there is a minimum of geologic control. The relative amplitudes and stacking velocities of seismic data comprise the required input; however, if sonic and density logs are available, this information also can be incorporated leading to greater control of the final results. The procedure requires that the shape of the propagating wavelet in the data be known and, for maximum resolution, should be a zero-phase wavelet.

The computerized part of the method yields velocity and density information for each stacked seismic trace which is displayed as velocity and density logs. An iterative scheme minimized the differences between the response of a geologic modeling system and the seismic data, on the basis of matching-amplitude ratios of the data. The method can be performed on as many stacked traces in an area as necessary.

Marine data from several different geologic provinces have been analyzed with this technique. When the results were compared to sonic and density logs in the proximity of the seismic data, the correlations were good.

AAPG Search and Discovery Article #90968©1977 AAPG-SEPM Annual Convention and Exhibition, Washington, DC