High-Pressure CO₂ Adsorption and Mineralogical Evaluation of Sandstones from the Mesohellenic Trough (Greece) for Geological Carbon Storage

Carbon capture and storage (CCS) is considered one of the most promising strategies for mitigating anthropogenic CO2 emissions and enabling a transition toward low-carbon energy systems. Well confined saline aquifers within porous geological formations of clastic rocks and lithology such as sandstones are particularly attractive candidates as reservoirs for long-term CO2 storage. This is mainly due to their favorable porosity, permeability, mineralogical composition, thickness and widespread distribution as exemplified by the Utsira Formation at the Sleipner Project in Norway [1]. The Mesohellenic Trough (MHT) represents a large sedimentary molassic basin located at the northern central Greece. Deposition of various geological formations commenced in Late Eocene and lasted up to the Early Miocene age. Since the sandstones are the dominant facies of the MHT formations and they are potentially suitable for CO2 sequestration applications, we explore their validity in this geologic regime. Previous studies have shown that sandstones from this region contain mineral phases capable of interacting with injected CO2, potentially leading to mineral trapping mechanisms and long-term storage stability [2,3]. The present study investigates the CO₂ adsorption behavior and structural evolution of a representative sandstone sample from the Pentalofos clastic formation of the southeastern MHT under high-pressure CO2 and temperature exposure conditions, simulating subsurface storage environments of a potential injection well.