3D Gravimetric Characterization of Two Potential Geological Storage Sites - La Rambla and Zafra de Záncara (Loranca Basin

In order to study its feasibility as storage sites, two elongated anticlines, namely La Rambla and Zafra de Záncara, located within the Loranca Tertiary Basin (part of the Tajo Basin) have been investigated, within the framework of the “Program of evaluation and characterization of Spanish areas for CO2 storage”. In this area, some vintage seismic profiles, deep oil exploration boreholes and geological cross-sections are available. Nonetheless, these data alone do not have enough resolution to provide a 3D image of the structure. To build a robust 3D model of the anticlines, a local gravity survey (1 station every km2) was carried out in the area. Densities for the geological formations of the model come from the analysis of rock samples and data from El Hito-1 and Belmontejo-1 drillholes. Within the anticlines, one of the targets as potential reservoir corresponds to the Buntsandstein sandstones and conglomerates and the Muschelkalk limestones, with the Keuper shales and evaporites as a seal. The 3D stochastic gravity inversion improves the knowledge about the geometry of the anticline traps as well as the basement relief, the structural relationship between basement and cover and how the faults affect the geological structures.