Quantification of Reservoir Heterogeneities and their Impacts on CO2 Plume Geometry

Site screening is the process of defining the place where a Carbon, Capture, and Storage (CCS) project could be developed. Applied in the early stages of evaluation, this process involves several critical variables that should be analyzed. For example, the distance of CO2 sources, injection forecasting, flow assurance, storage capacity, well injectivity, and the feasibility of monitoring methods. Once these major factors indicate a potential viable project, quantifying reservoir heterogeneities and their impacts on the geometry of CO2 plume is essential to develop optimized monitoring plans and select areas that are favorable for lower monitoring costs. This paper presents a methodology for quantifying heterogeneities in 3D reservoir models of a deep saline formation and correlated them with CO2 plume radius obtained from flow simulations. The variance of the geometric mean permeability, calculated according to the dimensions of geological elements, was used as a reservoir heterogeneity index that impacts CO2 plume behavior. Based on this analysis, it was possible to prioritize two subregions of 150 km² each as candidates for further detailed mapping within an area of nearly 4,000 km² in the shallow waters of the Santos Basin, Brazil.