Feasibility study to optimize a near-surface sensor network design for improving detectability of CO ₂ leakage at a geologic storage site

We explored the feasibility of an improved design of a CO ₂ leakage monitoring network at a geologic storage site. To effectively represent CO ₂ pathways, a rule-based percolation model was adopted rather than the rigorous multiphase flow model based on Darcy's equation. Five different monitoring network designs were compared using a few scenarios and multiple correlated random field realizations. The ensemble results showed that given the detection uncertainty across the entire sensor network, regular spacing deployment of sensors is the most effective method when a sufficient number of sensors is available. The results also showed that an aggressive monitoring design based on information of the spatial permeability distribution near the surface can be a viable method when a limited number of sensors is employed. However, such an aggressive design can lead to elevated uncertainty in leakage detectability.