Preliminary Analysis of the Potential for Managing Waste CO2 in a Middle Cambrian Aquifer Within the Polish Exclusive Economic Zone of the Baltic Sea

This article addresses the storage of carbon dioxide [CO2] in underground geological formations. It presents the results of a preliminary assessment of the feasibility of sequestering CO2 in Cambrian aquifer units located within the Polish Exclusive Economic Zone of the Baltic Sea. The northern segment of a structure within the Rozewie tectonic block was selected as the research and test site. The aim was to determine the sequestration capacity and select optimal locations for injection wells, taking into account storage safety. The results and conclusions are based on numerical simulations of CO2 injection and plume migration within a brine-filled structure using Petromod software v. 2024. A geological model of the site was developed representing the spatial distribution of petrophysical parameters (porosity and permeability) of the reservoir and sealing horizons. Fault zones were also mapped and parameterised in order to evaluate the structural integrity and identify potential migration barriers for the injected gas. An initial assessment assumed the possibility of injecting 100 Mt of CO2 into the analyzed structure over a 30-year period using ten wells. However, simulation results based on the current state of geological characterization demonstrated that injection performance may vary considerably between individual wells. Wells situated within zones of highest reservoir capacity were estimated to sustain injection rates of 6–7 Mt of CO2 over 30 years, implying that a greater number of injection wells would be required to accommodate the target storage amount. Fault seal capacity was evaluated using an algorithm based on the Shale Gouge Ratio (SGR) criterion, which enabled the assessment of fault permeability and revealed potential risks of CO2 leakage. Numerical simulations further facilitated the estimation of the reservoir’s storage potential and the optimization of injection well placement, considering both injection efficiency and the risk associated with CO2 migration and leakage.