CCS in Deep Saline Aquifers: Estimating Theoretical CO2 Storage Capacity of the Dutch Offshore Rotliegend Aquifers

Deep saline aquifers have the potential to contribute to the Dutch offshore portfolio for CO2 storage, alongside depleted gas fields. However, their storage potential is often understated. The study focusses on the Rotliegend aquifers in the Dutch offshore, which is considered here as a closed-system with impermeable (no-flow) boundaries and long-term (final) pressure state conditions. Probabilistic modelling was used to account for uncertainties in input parameters such as rock compressibility and the pressure and stress state of the formation.

The study provides a two-dimensional map of storage capacity and estimates between 990 and 3650 Mt (80% confidence interval) of theoretical CO2 storage capacity for the Rotliegend aquifers in the Dutch offshore.

For this aquifer storage potential to advance to a more practical and realistic range, further evaluations considering flow dynamics, and economic and legislative/regulatory constraints are essential. Ultimately such estimates are most valuable to policy- and decision-makers. It is expected that these ranges will narrow and decrease.

In addition to the Rotliegend aquifers studied in the Dutch offshore, the Triassic and Lower Cretaceous are also identified as stratigraphic groups holding CO2 storage potential in their aquifers and could be considered to be studied in the same manner as presented here.