Quantification of CO2 Storage Efficiency with Aquifer Pumping

Abstract

Summary Many Carbon capture and storage (CCS) projects make use of aquifers for CO2 storage. In the case of closed systems, pressure build-up will limit the storage capacity and challenge the caprock integrity. Water can be pumped out of aquifers through water production wells to relieve the pressure and provide additional storage volumes. CO2 breakthrough into water producers is a setback of aquifer pumping. By understanding the effect of key aquifer parameters, pressure management strategies and different pattern geometries, we can delay this problem until later stages of the project life. Most of the predictive models available are reservoir dependent and cannot be scaled for evaluating different fields. This project aims to quantify the additional storage efficiency with brine production. Results have shown that with favourable conditions of low mobility ratio, buoyancy viscous equilibrium and large well spacing exist; the breakthrough time can be postponed to more than 60 years and the storage efficiency can reach up to 13%. When a trade-off between pressure management, delay of breakthrough time, cumulative volumes of water produced and the associated expenses with pumping and disposing of water is to be considered, passive pressure management is a more reasonable option than active pressure management.