Seismic Interpretation of Prograding Events in Tortonian Sands, Vienna Basin - Implications for Stratigraphic Modeling

Tortonian deltaic reservoir sands in the Vienna Basin contain substantial remaining HC potential. These reservoirs have been extensively drilled and produced, previous studies could not fully explain reservoir connectivity issues. The recognition of heterogeneities in reservoir modelling studies is a precondition to understanding fluid flow behaviour. This study presents the detailed mapping of prograding seismic elements using Relative Acoustic Impedance (RAI) and Spectral Decomposition (SD) attributes. These attributes facilitate the identification of geologic patterns, such as gently dipping clinoforms previously unrecognized in forced regressive stage reservoirs in this area. The morphological characteristics suggest a complex reservoir facies distribution. The patterns observed are linked to a fast and changing interplay between accommodation space and sediment supply, different feeders and/or source-shifting that are inferred to be acting over the deposition area. This intricate scenario makes ambiguous the definition of flow units based on a purely lateral well-to-well log correlation. Higher accuracy in interpretation of flow units is achieved using the aforementioned seismic attributes in addition to traditional stratigraphic modelling methods. The value added with the use of attributes certainly impacts the geological understanding during integrated multidisciplinary reservoir model workflows.