Potential Damage Complications in Supercritical CO₂ Storage

Long-term underground CO₂ storage is the only practical solution for heavy industries to keep providing energy to the world and simultaneously to meet their net zero commitments by 2040 or 2050. Several challenges must be faced to accomplish the commitments in terms of underground long-term storage. One key parameter for subsurface CO₂ storage is well injectivity and understanding the interaction between the carbonic acid and different minerologies, such as clay minerals, carbonates, and salts present in the reservoir and how the CO₂ injection might potentially cause formation damage jeopardizing the capacity to inject into the well. The primary objective of this paper is to quantify the reduction on well injectivity, in terms of the reduction in core permeability due to CO₂ interaction with the rock. A core flood study will be conducted four core plugs with a range of clay content and permeability from a particular formation. CO₂ will be injected under supercritical conditions at a pressure of 1,500 psi, and at 150°F at injection flow rate of 1.0 cm3/min for seven and 21 days. Cores will be saturated with 35K NaCl brine and the effluent samples will be collected, and the concentrations of calcium, potassium, magnesium, aluminum, iron, and silicon ions will be measured by ICP. Precipitated material collected after the tests will be analyzed using XRD and XRF. The air and water permeability (Kair and Kw) will be measured before and after the test to evaluate the impact. Due to the low permeability condition of the samples, no permeability data was possible, only porosity through NMR was able to be performed. Post CO₂ exposure, a porosity variation was observed in the experiments. The change in porosity after CO₂ exposure was shown to be a function of carbonate content. The observed increase in porosity ranged between 0.1 p.u. in the sample with the lowest carbonate content and 2.5 p.u. in the sample with the highest carbonate content. CO₂ projects must include the geochemistry component in their geologic models to understand the complexity of seal conditions and risks on injectivity.