Estudio de afloramientos de unidades detríticas como posibles almacenes geológicos de CO₂ en la cuenca del Duero (España)

Carbon Capture and Storage (CCS) enables significant reduction of anthropogenic emissions of CO₂, and it is considered one of the main technologies in the fight against Climate Change. Selection studies and characterization of potential geologic formations and structures as CO₂ storage sites are expensive and also subjected to a high degree of unpredictability, especially when the structure is considered deep saline aquifer. In order to minimize the cost and exploration risk, it is necessary a previous stage of selection and subsequent characterization, which should include the identification of technical and socio-economic parameters and the study of storage and seal formations in their outcropts. The study of these outcropts would allow to estimate petrophysical, and geomechanical properties, as well as hydrogeological data. In this article, some results from the evaluation of several samples taken years ago by Spanish Geological Survey in the Duero Basin (Spain) are presented. After evaluating the petrophysical results, it can be considered as the most favorable unit the “facies Utrillas” since it presents the best values of porosity and permeability (Hg) and a more stable and mature mineral composition when compared to the red sandstones and arkoses of the Buntsandstein units. However, the presence of higher proportion of K-feldspar in the granular fraction of this last unit, could favour the mineral and ion trapping, but this consideration is based on qualitative data which should be evaluated in further studies, also evaluating the loss of porosity and permeability parameters.