Insights from Black Sea sandstone reservoir-quality screening

Spatial and temporal variations in reservoir presence, quality and volume are key uncertainties that need to be assessed during basin screening for both hydrocarbon exploration and gas storage (CO₂ and hydrogen). Over a 20+ year period we have been collecting sandstone petrographic and provenance data from regions surrounding and within the Black Sea, and placing these analyses within their tectonostratigraphic and palaeoenvironmental context. The resulting reconstructions of ranked palaeosediment dispersal systems can help with exploration screening programs, whilst the associated petrographic data can provide reservoir modelling input parameters for fields already in development. In this presentation, we shall use examples from the margins of the Black Sea to demonstrate how different Cenozoic depositional systems can be identified and their source areas/drainage configurations determined. We will then use these to postulate how Cenozoic drainage systems have evolved through time within the Black Sea and highlight key areas of potential exploration interest.

In general, depositional systems derived from the north, from the east European Craton and Scythian Plate, e.g. the palaeo-Don and Dnieper, are the most quartz rich. Larger systems sourced from the Carpathians (e.g. palaeo-Dniester) and the Russian Caucasus also include material recycled from these sources and are, likewise, relatively quartz rich. Systems derived from further south, from the Balkans, Pontides and the Georgian Lesser and Greater Caucasus, will have deposited sandstones with varying but generally lesser reservoir qualities. The Danube system currently dominates siliciclastic input into the Black Sea. Input began sometime between 4 and 1 Ma and is likely to result in the deposition of poorer quality reservoirs than earlier northern-derived systems supplying the same region.