Internal structure of the Upper Jurassic subsurface carbonate buildups of the northern Tethys shelf in southern Poland – integration of seismic forward modeling and outcrop analogs

Abstract

The Upper Jurassic carbonate buildups are considered to be exploration targets along the northern margin of the Tethys shelf in Central and Eastern Europe due to their prospective reservoir parameters. However, detailed internal structure of the Upper Jurassic subsurface buildups in the majority of the Polish part of the shelf remains largely uncharted. One of such under-documented areas is the Miechów Trough, where these structures are still poorly recognized in terms of their facies/microfacies composition and petrophysical properties. In order to fill these gaps, we have integrated the subsurface well and seismic data with sedimentological data from adjacent surface areas where equivalent reefs were documented based on facies/microfacies analysis. This paper presents the results of interpretation of the internal structure of the subsurface carbonate buildups, using seismic forward modeling supported by outcrop analogs. Eight main seismic intervals corresponding to internal levels of the Upper Jurassic succession were distinguished and integrated with the lithological intervals from the studied outcrops. The internal structure of the reefs is heterogenous and in terms of facies distribution it corresponds to that observed in adjacent areas of the Late Jurassic carbonate platform. The important aspect of the reefs internal structure is the existence of highly porous intervals, as they could be regarded as potential objects for further investigation as CO₂ storage sites. Modeling results proved that their detection using seismic data is primarily constrained by lateral resolution limits.