The Impact of Impurities on the CO2 Storage Capacity of Aquifers and Depleted Gas Reservoirs

This study evaluates the effects of impurity content and type on CO2 storage capacity in both saline aquifers and depleted gas fields at various depths, using reservoir parameters representative of the Dutch subsurface. It provides a general understanding of the impact of impurities on storage capacity and serves as an input for optimizing the efficiency of CCS projects.

The study found that depleted gas fields can store significantly more CO2 per unit of rock volume than saline aquifers—approximately 100 times more at a depth of 2 km and 70 times more at 4 km. Additionally, opposite capacity-depth trends are observed between depleted gas fields and aquifers for the modelled reservoir parameters.

The effect of impurities is comparable for both depleted gas fields and aquifer storage. Input stream composition representing the Aramis and Porthos project with a purity of 95 %volume at surface conditions result in a capacity loss ranging from 11% at 2 km depth to 6% at 5 km depth for depleted gas field scenarios. For aquifers, a range of 16% and 7% capacity loss was observed for 1 and 4 km depth respectively.