Prediction of thin-layer thickness using seismic full-wave modeling

The aim of the work is to select a method for studying the quantitative characteristics of the reservoir properties of the pre-Jurassic oil and gas complex of Western Siberia according to 3D seismic data and testing it on real data. The weathering crust in the Pre-Jurassic complex of Western Siberia was chosen as a methodological example, since with its relatively small capacity (from 0 to 50 meters) reflections from the roof and the sole are not separated. The amplitude-frequency response of this interference reflection depends on the thickness, and therefore some seismic attributes may react to this. To clarify these connections, full-wave seismic modeling using the spectral element method was used for the first time within the framework of the advanced domestic CAE FIDESYS software developed by graduates and staff of the Chair of Computational Mechanics of Lomonosov Moscow State University and adapted by staff and graduate students of the Geological Faculty of Moscow State University to solve the tasks set. This article presents the first results of their practical use. According to comparative calculations, it has been established that the traditional beam modeling methods previously used in seismics, coupled with convolution with reflection coefficients, give false results and therefore are not recommended for further use. The proposed and tested technology made it possible to build a forecast map of the thickness of the potentially oil and gas-bearing weathering crust in the roof of the of the Pre-Jurassic complex on the 3D survey area.