AVO Inversion–A Suitable Tool for Seismic Reservoir Characterization in the Ancient Reservoirs of the Baltic Syneclise

In the Polish sector of the Baltic Sea, Middle Cambrian sandstones are the main hydrocarbon bearing reservoir. The sandstones are several tens of meters thick, and due to their age, they are thoroughly compacted and may exhibit average porosities in the range of 10-12%. However, there are also areas with significantly lower porosities. The aim of the work was to investigate whether AVO inversion of the seismic data may help to map reservoir trends and properties. Albeit their age and associated with that, relatively low porosities and high velocities, the investigated sandstones show an AVO behavior typical of very clean quartz sandstones which clearly separates them from the overlying Ordovician marly limestones. The observed extremely low Vp/Vs ratios can be utilized for the identification of reservoir sweet spots and hence may help to reduce the further exploration risk.