An overview of the IEA greenhouse gas R&D programme regional geologic storage capacity studies

AbstractMapping of CO2 geological storage resources provides an important element in the planning of widespread CO2 capture and storage (CCS) deployment. Recent high-level studies by the IEA Greenhouse Gas R&D Programme (IEAGHG) have estimated realistic global capacity available in depleted oil and depleted gas fields to be 130 and 65 Gt, respectively, based on mass balance considerations from hydrocarbon reserve information. However, comparable estimates for deep saline formation (DSF) storage require an analytical approach that considers the fraction of pore space in storage formations that could be occupied by injected CO2. Many regional mapping initiatives have shown that potential DSF storage capacities are typically at least an order of magnitude higher than in depleted fields.Computationally similar methodologies to estimate DSF storage resources have been developed by the U.S. Department of Energy (DOE) and the Carbon Sequestration Leadership Forum (CSLF); in both, a storage coefficient, E (or efficiency factor), is used to derive resource estimates. The E coefficient takes account of various geological and technical factors that could restrict the amount of pore space available for storage but does not take into account economic, regulatory, and source-sink matching considerations.IEAGHG and DOE commissioned a study in 2008 by the Energy & Environmental Research Center (EERC), to improve the accuracy of storage coefficients for DSF. As there was insufficient real-world CO2 injection data to derive a representative range for E, geological input parameters were derived from global hydrocarbon reservoir data as a proxy for DSF. Modeling allowed derivation of probabilistic ranges of storage coefficients at both site-specific and formation levels for clastic, carbonate, and dolomite lithologies. The overall mean value of E for all lithologies was calculated as 2.6% at the formation level. A key assumption made in the study was that DSF will predominantly act as “open” systems, whereby pressure and displaced formation fluids can be safely dissipated through the wider storage formation and adjacent strata