Estimating the potential costs of brine production to expand the pressure-limited CO2 storage capacity of the Mount Simon Sandstone

The conventional wisdom is that widespread deployment of carbon capture and storage (CCS) is likely necessary to be able to satisfy baseload electricity demand, to maintain diversity in the energy mix, and to achieve mitigation of carbon dioxide (CO2) emissions at lowest cost (IPCC, 2014). If national-scale deployment of CCS is needed in the United States, it may be possible to store only a small fraction of the captured CO2 in oil and natural gas reservoirs (including as a result of CO2 stored in conjunction with utilization for enhanced oil recovery). The vast majority of the captured CO2 would have to be stored in brine-filled reservoirs (Dahowski et al., 2005). Given a lack of long-term commercial-scale CCS projects, there is considerable uncertainty in the risks, dynamic capacity (maximum rate of injection), and their cost implications for geologic storage of CO2. Pressure buildup in the storage reservoir is expected to be a primary source of risk associated with CO2 storage, and could severely limit storage capacities. Most current cost estimates for commercial-scale deployment of CCS estimate CO2 storage costs under assumed availability of a theoretical geologic capacity to store tens, hundreds, or even thousands of gigatons of CO2, without including the costs of the pressure management that will be necessary to make that storage capacity practically available. These assumptions often lead to considerable underestimation of the costs of CO2 storage (Anderson, 2017). We consider the potential impacts on CO2 storage capacity and costs of producing formation waters (brines) to manage pressure. Given that pressure limitations could constrain injection rates per well to be far below the design capacity of a typical CO2 injection well, brine production could possibly increase the efficiency of CO2 injection. We analyze the net costs of pressure management by producing brines. Our results could have implications for how long and to what extent decision makers can expect to be able to deploy CCS before transitioning to other low- or zero-carbon energy technologies.