Quantitative Seismostratigraphic Inversion of Seismic and Geophysical Data

Matthias Imhof and Arvind Sharma
Virginia Tech, Blacksburg, VA

An algorithm has been developed for quantitative seismostratigraphic inversion of seismic data. Quantitative stratigraphy predicts the geometry of geologic strata and their petrophysical properties based on mathematical models of geological processes and parameters which affect the formation and evolution of geologic strata. Such processes include erosion, sediment transport, and deposition.

The initial work involved applying this algorithm to a synthetic data set, now we apply it to 3-D seismic field data from a prograding delta in West Africa. The results of the inversion can be used to obtain an accurate picture of the depositional process history in the study area. We use stratigraphic inversion, not in the traditional geophysical sense of converting seismic amplitude to seismic impedance, but rather in the stratigraphic sense. We found that by fixing the sediment influx rate, subaerial transport rate, and the initial topography, we were able to reproduce the basic geometric features of the delta with only three to five parameters which included subaequeous transport rate and depth-dependent decay rate, base level, and sediment source location and its spatial extent. Analysis of the results showed that not all parameters were equally important. The subaequeous transport rate, baselevel, and sediment source location had a great effect on the resulting realization. The other two parameters had little effect on the results. Ultimately, the inversion results were able to recreate the geometry of the current day delta and processes behind its deposition.