Theoretical Capacity Assessments for CO2 Storage in Deep Saline Aquifers at Two Different Scales: An Analytical Model for Individual Complexes and a Map-Based Approach for Regional Analysis

Abstract Two methods are presented that provide an estimate for the theoretical storage capacity for CO2 in closed-system deep saline aquifers. On a local, individual aquifer scale, an analytical model estimates storage capacity and indicates the most sensitive parameters. On a regional scale, a map-based workflow has been applied to the Rotliegend aquifer of the entire Dutch offshore to obtain a regional map of CO2 storage potential. Both methods include probabilistic modelling and have been based on subsurface data of the Geological Survey of the Netherlands. Applying the analytical model to average values for the rock and fluid properties of the Rotliegend aquifer in the Dutch offshore resulted in about 1% of storage efficiency (ratio of volume injected to the aquifer's pore volume). This is twice as low as the common value for storage efficiency reported in previous literature. Applying the map-based methodology resulted in a map that indicates a theoretical CO₂ storage capacity ranging between 1.0 and 3.5 Gt, with an 80% confidence interval. It is reasonable to assume that the storage capacity to be realistically developed will be considerably lower, owing to various factors, such as economic constraints, legislative frameworks, and surface restrictions. Besides the maximum allowable aquifer pressure, it is shown that the frame compressibility parameter is the most sensitive parameters for estimating theoretical storage capacity for closed aquifer systems, due to the uncertainty associated with this parameter.