How tight are top seals? Insights from a comprehensive characterization workflow

Abstract

Summary In this contribution, an effective Middle Miocene (Badenian) top seal within the Vienna Basin was investigated to refine the understanding of the factors controlling sealing capacity. A comprehensive characterization workflow was developed to provide detailed characterization of the aforementioned seal properties and evaluate their mutual interactions. Multiple petrophysical and image-based porosimetry techniques were applied to capture multiscale (nm to mm) pore structure. Additionally, geochemical and mineralogical analyses were conducted to trace the hydrocarbon migration and compositional variations, while mechanical measurements were performed to investigate the compaction effect. The contribution demonstrates the capabilities of different state-of-the-art characterization techniques in linking multi-scale properties of top seal rocks and investigated the possible influence of the measured compositional, structural and mechanical properties on the overall seal capacity. It was highlighted that a working seal can be naturally imperfect (i.e., unlike an ideal impermeable tight layer) and yet still effectively seal reservoir units through geological time.