Contributions of GeoSeismic Modeling
Seismic modeling is in fact the successor to the synthetic seismogram and is also the vehicle by which seismic correlations with geology may be verified. Although publications describing modeling techniques and applications are few in number (see Taner, Cook and Neide11 (1970) and Shah (1973), the technology has reached a rather sophisticated level. The paper by Neidel1 (1975) describes some of the more advanced considerations and limitations associated with the use of seismic modeling.
Unlike the synthetic seismogram, the true seismic model accepts a description of a subsurface in terms of its geometry and acoustic parameters including the usual velocity, density and an attenuation factor. In two-dimensional modeling systems which view the subsurface as having perfect lateral continuity and homogeneity outside of the plane in which the subsurface is described, geometry of virtually any complexity may be treated. Further, the seismic parameters are permitted to vary both horizontally and laterally to represent lithologic transitions and similar subtle stratigraphic effects.
In our introductory discussion we briefly viewed simple modeling illustrations using ray trace approaches and wave theory. These portrayed modeling as a tool for overcoming geometric effects on the seismic section which might obscure stratigraphic objectives and also for treating diffractions, another member of the class of seismic events which do not simply relate to lithologic contrasts. Here we wish to look at modeling from a more advanced viewpoint. In particular we will use it to develop insights into the spatial resolution inherent in seismic data and the very origin of
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Stratigraphic interpretation of seismic data requires that the seismic information be expressed in geological terms. The strictly geological view of the earth is developed from surface observations, guiding principles of geological evolution and subsurface information from bore holes. Seismic measurements on the other hand, define in some sense the subsurface geometry and give estimates of the acoustic impedance which is related to the rock velocities and densities. This publication contains eight chapters on: relating seismic data to stratigraphy; information content and resolution potential of seismic data; processing for preservation of seismic amplitudes; the role of seismic wavelets and wavelet processing; contributions of geoseismic modeling; qualitative stratigraphic correlations; quantitative stratigraphic correlations; and conversion of seismic data to log-like displays.